Lower Extremity Injuries

Anatomy

The pelvis is formed from the sacrum and the three primary centers of ossification—the ischium, ilium, and pubis. The three centers of ossification join at the acetabulum, referred to as the triradiate cartilage in the pediatric pelvis. The triradiate cartilage typically fuses in both males and females at around 14 years old ( Fig. 30.1 ). At the ischiopubic rami, fusion of the ischium and pubis takes place at 7 to 11 years of age. Secondary centers of ossification of the pelvis are listed in Table 30.1 with noted range of appearance and closures.

The sacroiliac joint is made up two components: an inferior segment that is articular and a dorsal segment that is fibrous and ligamentous. The sacroiliac joint is not a true synovial joint because it consists of articular cartilage on the anterior sacral side and fibrocartilage on the iliac side. When a person is standing, the sacrum is driven between the iliac wings and creates a dorsoventral rotation such that the pelvis moves posteriorly and the rami rotate upward. This movement produces the normal tilt of the pelvis.

The sacroiliac joint owes its stability to its strong anterior and posterior ligamentous structures as well as intrapelvic ligaments and pelvic-lumbar ligaments. The anterior ligamentous structures, weaker than the posterior structures, are composed of a flat ligament running from the ilium to the sacrum. Posteriorly, short and long ligaments are present; the short posterior ligaments travel obliquely from the posterior ridge of the sacrum to the posterior superior and posterior inferior spines of the ilium, whereas the long posterior ligaments are longitudinal fibers running from the lateral sacrum to the posterior superior iliac spines. These ligaments then merge with the sacral tuberous ligament. The sacrotuberous ligament connects the posterolateral aspect of the sacrum and the dorsal aspect of the posterior iliac spine to the ischial tuberosity. This ligament’s primary role is to assist in maintaining vertical stability of the pelvis in conjunction with intact posterior sacroiliac ligaments. The sacrospinous ligament connects the lateral aspect of the sacrum and coccyx to the sacrotuberous ligament and inserts on the ischial spine. The sacrospinous ligament is important in maintaining rotational stability of the pelvis. The iliolumbar ligaments connect the transverse processes of L4 and L5 to the posterior iliac crest. The lumbosacral ligaments run from the transverse process of L5 to the ala of the sacrum.

Other organ systems that lie adjacent to or within the pelvis include the nervous, genitourinary, and vascular systems; these may be susceptible to a combined injury with a pelvic fracture. The lumbosacral coccygeal plexus enters the pelvis and is composed of the anterior rami of T12 through S4. With some considerable variation, the sciatic nerve exits the pelvis from beneath the piriformis muscle and enters the greater sciatic notch ( Fig. 30.2 ). Major vascular channels lie on the inner wall of the pelvis. The common iliac vessel divides and gives off the internal iliac artery, which lies over the pelvic brim, and the superior gluteal artery, which crosses over the anteroinferior portion of the sacroiliac joint to exit the greater sciatic notch, where it lies directly on bone. The bladder lies superior to the pelvic floor, and the urethra passes through the prostate in male patients to exit the pelvic floor. The membranous urethra is the initial portion at the upper surface (followed by the bulbous portion, below the pelvic floor).

Mechanism of Injury

Injuries of the pelvis in children differ from those in adults in several ways. For example, children and adolescents are subject to apophyseal avulsion injuries, often while playing sports (see Chapter 40 ). In addition, growth plate injuries may occur in the acetabulum that can be missed on standard radiographs and that can hinder further growth, leading to an acetabular dysplasia or a leg length inequality. Unlike adults who sustain pelvic ring fractures and typically were occupants of a vehicle, children with pelvic fractures are often pedestrians who have been struck by a motor vehicle. This mechanism of injury accounts for more than half of pelvic fractures in children, with up to 83% of all pelvic ring injuries in children occurring due to a motor vehicle accident. Many of these children have not only been struck but also directly run over by the vehicle. Other causes of pelvic fractures in children include falls from a height (1.8% to 15.9%), bicycle (0% to 18.8%), and, less commonly, sporting injuries (0% to 15.1%) ( Table 30.2 ).

Classification

Several classification systems have been devised for pelvic fractures in adults. ^{, ,} These classifications are based on the anatomic site of the fracture, the mechanism of injury, and the mechanism and stability of the pelvic fracture.

Because of differences in anatomy and fracture patterns in children and adolescents, separate classifications for pediatric pelvic fractures have been developed. ^{, , ,} Watts divided pelvic fractures according to their radiographic findings: group I, avulsion injuries, usually of the anterior superior or inferior iliac spine and the ischial tuberosity; group II, fractures of the pelvic ring, both stable and unstable; and group III, acetabular fractures.

A more recent pelvic fracture classification scheme was described by Torode and Zieg. It is a four-part classification based on the radiographic examination findings: type I, avulsion fractures; type II, iliac wing fractures; type III, simple pelvic ring fractures; and type IV, ring disruption fractures that are unstable ( Fig. 30.3 ). Shore and colleagues proposed a modification to this classification to include IIIA and IIIB, in which IIIA includes stable anterior pelvis ring fracture while IIIB are stable anterior and posterior pelvic ring disruptions. This new classification scheme correlates well with fracture outcome, management, length of stay, and the type of treatment required. A study by Shore and associates found a relationship between increasing fracture type and both length of stay and transfusion. Type IIIB was more likely to receive a transfusion compared to type IIIA (odds ratio [OR] 3.58).

Associated Injuries

The high energy that produces pelvic fractures commonly results in visceral and vascular injuries, which may be fatal. The mortality associated with pelvic fractures in children is reported to be between 2% and 11%. ^{, ,} The probability of associated injuries is highest (60%) when multiple fractures of the pelvic ring are present, followed in frequency by iliac or sacral fractures (15%) and finally by isolated pubic fractures (1%). Similarly, resuscitation requirements are greater in patients with unstable pelvic fractures than in patients with stable fractures.

The injuries that may accompany a pediatric pelvic fracture are often more clinically relevant than direct fracture care. Fatalities in children with pelvic fracture usually result from visceral and head injuries. In one review, 91% of pediatric patients with pelvic fractures who required transfusions had hemorrhage attributable to another site. Intraabdominal injury occurs in up to 15% of patients with pelvic fractures and includes contusions or lacerations of the spleen, liver, or kidney and very often mesenteric injuries or injuries to the large or small intestine. Modern approaches to treating intraabdominal injuries in children have reduced the rate of laparotomies performed for the assessment and management of these injuries. ^,

The reported incidence of neurologic injury in children with a pelvic fracture is 50%. Concussion is the most common neurologic injury (33%), followed by skull fracture (16%), nerve avulsion (5%), and brain death (4%).

Associated musculoskeletal injuries occur in up to 100% of cases, with a higher incidence in patients with unstable pelvic fractures. ^, The most common fractures involve the femur, skull, upper extremity, and tibia or fibula. ^,

Associated injuries related to the vascular system are most often caused by venous bleeding and subsequent retroperitoneal hematoma, which occurs in up to 46% of patients. In one series of patients with retroperitoneal hematomas, 10% were in hypovolemic shock at initial evaluation and required the administration of whole blood or packed cells. Major arterial injuries, in contrast, are relatively rare and occur in approximately 3% of patients.

Genitourinary injuries generally occur in individuals, particularly females, who have sustained more severe pelvic injuries, with a reported incidence of 10% to 20%. ^{, , , , ,} Severe injuries requiring treatment, such as bladder rupture or urethral laceration, occur in association with less than 1% of pelvic fractures in children. Perineal or vaginal laceration may also be seen and can also be associated with bladder or urethral injuries. ^, Erectile dysfunction can be a long-term sequelae of a pelvic ring injury with associated urethral injury.

Clinical Features

A history of a child struck by a car while walking or running should alert the physician that pelvic trauma has potentially occurred. The details of the accident are important, including the speed of the traveling vehicle, the direction in which the child was struck, and whether the child was directly run over by the vehicle. An understanding of the exact mechanism can assist a trauma provider in the assessment of a pelvic ring injury or intraabdominal injury that might otherwise not be obvious on initial assessment, as a routine pelvis radiograph is not always indicated in a pediatric trauma patient.

The physical examination by the orthopaedic surgeon should be thorough, organized, and include the entire musculoskeletal system. It should begin with inspection of the entire body, including the perineal area, followed by palpation and assessment of pelvic stability, and finally a thorough assessment of the peripheral pulses and a neurologic examination.

The patient should be inspected for lacerations, abrasions, and evidence of tire marks on the skin, with the child “log-rolled” to allow careful inspection of the entire body. A child who sustained a severe crush injury may have a significant soft tissue injury in which subcutaneous fat and skin are sheared off the underlying fascia, the so-called Morel-Lavallee lesion. ^, This injury is most often seen in an obese child over the greater trochanteric region in the case of acetabular fractures and in the buttock region in the case of lateral compression–type injuries of the pelvis. Deformity of the pelvis and the extremities should also be evaluated. The child’s hips should be rotated to assess for asymmetry, especially in the setting of a lateral compression–type injury. Limb length is also assessed, especially with a vertically unstable pelvic fracture.

Palpation of the pelvis is performed to assess for bony tenderness, sacroiliac joint tenderness, and stability of the pelvis in the anteroposterior (AP), mediolateral, and vertical planes. Any pain on palpation of the bony prominences (as well as pain in the sacroiliac joints or sacrum) should lead to suspicion of a pelvic fracture. Pain with anteriorly directed pressure along the anterior superior iliac spines or with medially directed pressure along the iliac wings should alert the clinician to an open-book–type fracture or a lateral compression–type fracture, respectively.

Vertically unstable fractures are difficult to assess by palpation but may be implied by an oblique-appearing pelvis or a limb length discrepancy. Although arterial injuries are rare, the lower extremity pulses should be carefully palpated and further assessed by Doppler examination if a discrepancy between extremities is present. A careful neurologic examination is performed to assess the lumbosacral plexus.

Careful inspection of the perineal area is essential. Blood at the urethral meatus or a scrotal hematoma may indicate a urethral injury. In the setting of significant fracture displacement, the vagina and rectum should be inspected for tears. A rectal examination is performed to assess rectal tone, evaluate the position of the prostate in boys, palpate rectal tears, feel for fractures, and attempt to elicit pain on palpation of the bony pelvis. A digital pelvic examination should be performed in girls and is best done while the child is under sedation, if possible, especially a young child, and is ideally performed by a gynecologist.

If hemodynamic instability is present in the emergency department in a patient with a type IIIA, IIIB, or IV pelvic ring fracture, a pelvic binder or a bedsheet wrapped around the patient’s pelvis, compressing the pelvis and creating a tamponade effect of the active arterial bleeding, should immediately be applied to avoid persistent hemorrhage in the retroperitoneal space. Pelvic compression can help maintain hemodynamic stability temporarily while resuscitation ensues, or while a more permanent solution for pelvic stability, including a external fixator, is found. In this setting, computed tomography (CT) with angiography may be helpful. ^{, ,}

Routine pelvic radiographs in major pediatric blunt trauma are not recommended due to the rarity of severe bleeding from pelvic causes. Life-threatening bleeding from pelvic or acetabular fractures in pediatric trauma is estimated to occur in 2.8% of fractures. In the absence of high-risk clinical findings and high-risk mechanism of injury for pelvic fractures ( Table 30.3 ), there is a very low risk of a pelvic fracture. ^, In the presence of any high-risk clinical finding or mechanism of injury, a pelvic radiograph is recommended.

Radiographic Findings

Several studies have shown that most clinically significant pelvic fractures can be predicted by physical examination in alert patients without neurologic impairment. ^, When young age, neurologic impairment, sedation, or distracting injury could prevent an accurate examination, a screening AP radiograph of the pelvis is recommended. A radiology technician should be ready when the patient arrives in the emergency department; the pelvic radiograph should be obtained while the patient is being stabilized, and associated trauma radiographs are taken during the standard trauma algorithmic assessment.

Other plain radiographs that should be obtained to assess for pelvic fractures include inlet and outlet views. The inlet view is obtained with the patient supine and the x-ray beam aimed caudad 60 degrees and therefore at right angles to the pelvic brim; it allows visualization of the iliopectineal line, the pubic rami, the sacroiliac joints, and the alae and body of the sacrum ( Fig. 30.4 ). The inlet view is best used to assess for the following: anterior and posterior displacement of the pelvic ring, especially posterior displacement of the sacroiliac joint, sacrum, or iliac wing; internal rotation deformities of the pelvis; and sacral impaction injuries. The outlet view is obtained by directing the x-ray beam 45 degrees cephalad ( Fig. 30.5 ) and helps define superior-to-inferior displacement of the pelvic ring, superior rotation of the hemipelvis, and the sacral foramina, which are best seen in this view.

Because abdominal CT is common for the evaluation of visceral injury in pediatric blunt trauma, CT images of the pelvis may be available early in the evaluation of these patients. Reviews have confirmed the utility of these CT images for diagnosis and management of pediatric pelvic fractures without the addition of plain radiographs. ^,

Normative values on CT scans have been established ( Table 30.4 ) and are useful in determining nondisplaced injuries at the pubic symphysis and SI joint.

Treatment

A majority of pelvic ring fractures in pediatric trauma can be treated nonoperatively. Operative treatment for pelvic ring fractures are reserved for significantly displaced fractures, unstable fractures, or open fractures. A careful evaluation of pelvic stability must include both a clinical and a radiographic assessment.

Types of Injuries (Torode and Zieg Classification)

Type I: Avulsion Fractures

See Chapter 40 .

Type II: Iliac Wing Fractures

Type II fractures represent approximately 15% of all pelvic fractures in children, a slightly higher percentage than in adults. ^, The mechanism is usually an external force exerted on the iliac wing that results in disruption of the iliac apophysis or a lateral compression–type wing fracture ( Fig. 30.6 ). Patients are most often pedestrians struck by a motor vehicle, although direct trauma from other objects may result in this injury. Associated abdominal injuries are less common than with types III and IV fractures; the incidence of genitourinary injuries is 6%, and laparotomy is needed in 11% of patients. However, these injuries can lead to significant blood loss, and blood transfusions are necessary in up to 17% of patients. Fracture displacement is most often lateral and is usually mild because of the vast muscle attachments.

Type I	Avulsion fractures
Type II	Iliac wing fractures
Type III	Simple pelvic ring fractures
Type IV	Pelvic ring disruption fractures

Treatment generally consists of admission to the hospital for observation of the musculoskeletal injuries, hemodynamic status, and associated intraabdominal injuries. Ileus may develop after an iliac wing fracture and must be carefully evaluated by a general surgeon.

Although pain initially limits the patient’s activities after the injury, most patients quickly regain their mobility. Fracture healing is generally rapid, and functional limitations are rare with this type of injury, although some patients may have delayed ossification of the iliac apophysis or a prominent bump from ossification of the injured area.

Type III: Simple Pelvic Ring Fractures

This injury includes fractures of the pubic rami, disruptions of the pubic symphysis, fractures or separations of the sacroiliac joints, or displaced fractures in which no clinical instability can be detected. A type IIIA simple pelvic ring fracture includes anterior fractures only ( Fig 30.7 ), while a type IIIB includes stable anterior and posterior pelvic ring fractures ( Fig. 30.8 ). This is the most common fracture type and accounts for up to 55% of all pelvic fractures in children. ^{, , ,} Unlike the situation in adults, in whom a pelvic fracture in one part of the ring must be associated with fracture in another part, children can have a fracture or fractures in a single aspect of the pelvic ring without an associated fracture. Presumably, this is the result of the elasticity of the sacroiliac joints and pubic symphysis, which allows some strain to occur without radiographic evidence of injury. A single fracture with significant displacement but without posterior ring injury should be classified as a type IIIA fracture because the overall stability of the pelvic ring is intact.

Type IIIB includes fractures of the sacrum and coccyx. Fractures of the sacrum are relatively rare, with a reported incidence of 1% to 12%. ^{, ,} These fractures are best viewed on an AP or outlet view of the pelvis and are important to recognize because they can result in injury to the sacral nerves. Most sacral fractures are undisplaced transverse fractures through a sacral foramen and rarely require operative intervention. Coccygeal fractures are difficult to diagnose from radiographs because of the considerable normal anatomic variability. The diagnosis is therefore most often made clinically when tenderness is noted over the coccyx. Treatment is nonoperative with symptomatic pain management, including sitting on a donut cushion until symptoms resolve.

Type III fractures can be associated with a higher incidence of other musculoskeletal injuries than are type I or II injuries, including musculoskeletal (50%), genitourinary (26%), and neurologic (57%) injuries. Careful assessment of these potential associated injuries is important.

Stability of a type IIIA or IIIB pelvic ring fracture can be confirmed by a weight-bearing AP pelvis radiograph. If stable, position of pelvis and fracture should be stable and thus confirm diagnosis of a simple type IIIA or B pelvic ring injury. Patients with these simple ring fractures do well with nonsurgical treatment and progressive weight bearing until they are comfortable and independent on crutches or with a walker. Fracture healing is rapid with an undisplaced fracture; however, it may be delayed with a displaced fracture. Disruption of the pubic symphysis may occur as an isolated injury or, more often, with injury to the anterior capsule of the sacroiliac joint or partial separation of the adjacent ilium, or both. However, these injuries are stable because of the posterior structures (joint capsule, periosteum, and ligamentous structures) of the sacroiliac joint. Isolated disruptions of the pubic symphysis without significant injuries to the posterior ring occur at the bone–cartilage level, thus allowing healing to be complete without residual instability.

Type IV: Pelvic Ring Disruption Fractures

Pelvic ring disruption fractures include the following: bilateral pubic rami fractures, or so-called straddle fractures; double-ring fractures or disruptions (e.g., pubic rami fracture and disruption of the sacroiliac joint); and fractures of the anterior structures and acetabular portion of the pelvic ring (for acetabular fractures, see the discussion of treatment of acetabular fractures) ( Fig. 30.9 ).

Type IV fractures have the highest incidence of associated genitourinary, musculoskeletal, and neurologic injuries and also result in significant intraabdominal injuries requiring laparotomy. In addition, the mortality rate has been reported to be as high as 13%. In addition, up to 62.5% of these fractures may require transfusions and a period of observation in the intensive care unit.

Straddle Fracture

Straddle fractures consist of bilateral fractures of both the superior and inferior rami or separation of the symphysis pubis along with ipsilateral fractures of the superior and inferior rami ( Fig. 30.10 ). A straddle fracture generally results from a fall while straddling an object or from a lateral compression–type injury. Associated injuries to the genitourinary system are fairly common; the reported incidence is as high as 20%. ^,

Nonsurgical treatment consists of bed rest with the hips slightly flexed to relax the abdominal muscles, which tend to displace the fracture fragments. The hips should also be in mild abduction to prevent adductor muscle tension. The duration of bed rest depends on the amount of displacement and pain present; most patients need 2 to 3 weeks. Weight bearing is begun as tolerated by the patient.

Double-Ring Fracture

The second group of type IV fractures includes vertically or rotationally unstable pelvic fractures (or both), which account for approximately 20% to 30% of all pelvic fractures in children. ^, A complete description of the analogous injury in adults has been described and the injuries have been classified by Young and Burgess, Pennal and colleagues, and Tile. Because these injuries are rare, specific treatment protocols are not as well defined in children. Historically, treatment has consisted of conservative management involving the use of pelvic slings and skeletal traction. However, more recent developments in treating adult pelvic fractures have been applied to pediatric fractures, with promising results.

Pelvic asymmetry may predict the need for intervention in pediatric pelvic fractures. A review of 20 patients (average age, 9.5 years) with unstable pelvic fracture patterns at an average of 6.5 years after treatment found that more than 1.1 cm of pelvic asymmetry after operative or nonoperative treatment was associated with lower functional outcome scores. Additionally, no remodeling of pelvic asymmetry was seen in this study group.

The following treatment guidelines are based on the Young and Burgess classification. In general, children younger than 10 years with minimal pelvic asymmetry do well with nonoperative treatment and need less operative intervention. Lateral compression fractures in which the posterior structures and bone are intact (types A1 to A3) and anterior compression fractures without posterior sacroiliac joint disruption or posterior ring or displaced sacral fractures (types B1 and B2) do not usually need operative intervention. The only exception is when significant hemodynamic instability is present, and in such cases emergency application of a pelvic external fixator is required to decrease pelvic volume and tamponade the venous bleeding. Anterior compression injuries with displaced posterior pelvic fractures or sacroiliac joint disruptions (type B3) and vertically and rotationally unstable fractures (type C) require operative intervention, which generally consists of open reduction and internal fixation (ORIF).

Lateral Compression

A lateral compression–type injury ( Fig. 30.11 ) that produces an anterior pelvic ring fracture and partial sacroiliac injury in which the anterior ligaments are injured but the posterior ligaments are intact results in a rotationally unstable but vertically stable pelvis. Therefore, treatment is bed rest, followed by advancement of crutch walking, non–weight bearing on the affected side for 6 to 8 weeks, and then weight bearing as tolerated by the patient. In a patient with a displaced lateral compression fracture of the A2 or A3 type, ORIF can be performed.

Anterior Compression

Anterior compression–type injuries ( Fig. 30.12 ) in children younger than 10 years usually heal without difficulty and respond to nonoperative, symptomatic treatment as outlined earlier, which may include immobilization in a hip spica cast in some extremes. In an older child with a symphysis pubic diastasis of less than 3 cm, nonsurgical treatment is appropriate; however, if the diastasis is greater than 3 cm, open reduction of the diastasis should be considered. In fractures with complete disruption of the posterior structures and complete (vertical and rotational) instability, closed reduction followed by percutaneous screw fixation of the sacroiliac joint, with or without ORIF of the symphysis pubis, should be performed.

Vertical Shear

A Malgaigne-type injury ( Fig. 30.13 ) is characterized by complete disruption of the entire hemipelvis with a vertical shear injury and vertical displacement. The patient has a limb length discrepancy with a vertically and rotationally unstable fracture. In a young child this injury can often be treated by skin or skeletal traction to reduce the vertical displacement and stabilize this highly unstable fracture. Traction is generally needed for 2 to 3 weeks, until the fracture has stabilized sufficiently to allow hip spica cast application or until it has fully healed. In a child older than 10 years or with remaining pelvic asymmetry, traction to reduce the pelvis is followed by percutaneous fixation of the sacroiliac joint. The anterior aspect of the pelvis is stabilized by either external or internal fixation. As in other pelvic injuries, as trauma surgeons become more adept at surgical methods, these patterns will become more amenable to operative fixation.

Treatment Techniques

External Fixation

Two main indications for the use of an external fixator are recognized. The first is the existence of significant hemodynamic instability that is refractory to blood and fluid resuscitation. In this setting an external fixator is placed to reduce the volume of the pelvis in an attempt to tamponade the venous bleeding. We recommend applying the external fixator in the operating room under sterile conditions.

The second indication for the application of an external fixator is an anterior pelvic ring displacement associated with posterior instability in a rotationally and vertically unstable fracture pattern. In this setting, external fixation should be applied in conjunction with internal fixation of the posterior injury and should not be used alone ( Fig. 30.14 ). The frame may be used as temporary or definitive fixation of the posterior injury.

In an emergency situation in which hemodynamic instability is present, an external fixator can usually be applied quickly to the anterior aspect of the pelvis ( Fig. 30.15 ). When emergency application is required, a single pin or screw is placed on each side of the pelvis, and then the external fixator bars are assembled and the pelvic displacement is reduced. The goal of this treatment is to reduce the pelvic volume and provide indirect hemostasis. The choice of pin size depends on the age and size of the child, with standard adult-size 5.0-mm Schanz pins used in children older than 8 years and smaller external fixator pins used in younger children.

Because the iliac wing is directed obliquely lateromedially, it is important to direct the drill bit and pins laterally to medially at an approximately 30-degree angle from a vertical line to avoid perforating the medial or lateral cortex. A small incision is made over the anterior superior iliac spine in a transverse direction to allow the pins to slide along the incision during the reduction maneuver. This is followed by predrilling with a 3.2-mm drill bit (if 5.0-mm Schanz pins are used). The pin is then advanced by hand, with a T-handled chuck used to allow the pin to advance between the inner and outer cortical walls of the pelvis. The threaded aspect of the pin should be completely buried in the thickened anterior aspect of the iliac wing. If a second pin is used, it is placed approximately 1 to 2 cm away from the first pin to provide greater stability.

After the pins have been placed, the external fixator bars are loosely attached to the pins just before reduction. The surgeon must understand the nature of the pelvic displacement before undertaking the reduction. With vertical displacement of the pelvis, axial traction on the appropriate extremity is required; with rotational deformity, the pelvis must be rotated to achieve reduction. After reduction, the external fixator frame is tightened to stabilize the pelvis, and radiographs are obtained to confirm the reduction. The frame is inspected to ensure that it allows adequate room for the abdomen, and it should be positioned so that the patient can sit in a reclining chair.

Open Reduction and Internal Fixation of the Symphysis Pubis

The indications for ORIF of the symphysis pubis are similar to those for external fixation of the pelvis: (1) fractures with more than 3 cm of symphyseal displacement; and (2) unstable, open-book–type fractures with posterior ring disruption. This technique should not be used when the patient is hemodynamically unstable because soft tissue dissection may aggravate the blood loss and result in increased instability. External fixation can be done more rapidly and without such tissue disruption.

A Foley catheter should be placed to decompress the bladder. A standard transverse Pfannenstiel incision is made approximately one fingerbreadth above the pubic tubercle and to the point of the external pelvic ring ( Fig. 30.16 ). The spermatic cord is identified and retracted out of the operative field. The rectus sheath is divided above the symphysis, and the fatty tissue anterior to the bladder is bluntly dissected off the anterior symphysis. The anterior rectus sheath has usually been avulsed from the pubis at the time of injury; however, if it remains intact, it should be incised transversely, with a small attachment left so that the rectus sheath can be sutured back into place after fixation of the fracture. A sponge should be packed behind the symphysis to protect the bladder. Subperiosteal dissection is then carried out laterally until enough exposure is attained for plate fixation. We prefer dynamic compression or pelvic reconstruction plates (3.5 mm) when the child is large enough and four-hole plates when possible, although two-hole plate fixation appears to be stable enough in children younger than 12 years. In a very young child (<8 years), two-hole semitubular or one-third tubular plates can be used effectively. Hohmann retractors are placed around the symphysis, and reduction is best achieved by placing bone reduction forceps in the obturator foramen. Anatomic reduction should be achieved under direct visualization.

Internal Fixation of the Sacroiliac Joint

Injuries to the sacroiliac joint, including dislocations and fracture-dislocations, can be approached through open exposure of the joint, either anteriorly or posteriorly, ^{, , ,} or they can be treated by closed reduction followed by percutaneous fixation. An open technique is needed to achieve anatomic reduction when the sacroiliac joint has been disrupted. This disruption is rarely seen in children’s pelvic injuries and is not generally necessary for appropriate treatment. We prefer to perform closed reduction followed by percutaneous internal fixation under fluoroscopic guidance as safe sacral screw pathways have been demonstrated to exist in ages greater than 2 years old. ^{, ,} Posterior open reduction is needed if closed reduction is unsuccessful or in patients with a significantly displaced sacral fracture.

The posterior approach requires the patient to be placed prone on the operating table. A vertical incision is made 2 cm lateral to the posterior superior iliac crest. The gluteal muscles are subperiosteally reflected off the posterior iliac wing. The origin of the gluteus maximus is reflected off the sacrum, and the greater sciatic notch is exposed to visualize the fracture reduction fully. To identify sacral fractures, the dissection is carried down to the sacral notch by reflecting the gluteus maximus fibers, the erector spinae, and the multifidus muscles. Internal fixation can usually be performed with single- or double-screw fixation, as described later, or with 3.5-mm reconstruction plates.

For percutaneous screw fixation, we prefer to place the patient supine on a radiolucent operating room table with the pelvis positioned on a flat elevated surface (one or two bed sheets). An image intensifier is used to image the sacroiliac joints and the sacrum in three views: a straight AP view, a 40-degree cephalad view (outlet view), and a 40-degree caudad view (inlet view). The inlet view shows the screw placement in the axial projection, and the operator examines the screw to be sure that it is not too anterior or posterior. The outlet view shows the screw in the cephalocaudal orientation, and the operator ensures that the screw is between the neural foramina ( Fig. 30.17 ). In a child older than 10 years, we prefer to use a 6.5- or 7.3-mm cannulated cancellous screw, and in a younger child we use a 5.5-mm cannulated cancellous screw.

Intraoperative stimulus-evoked electromyography can be used to decrease the risk for iatrogenic nerve injury during the placement of percutaneous screws. ^, Both legs are prepared and placed in the operative view to allow manipulation for reduction purposes. Reduction of the sacroiliac joint requires that traction be placed on the leg and manual compression be applied across the sacroiliac joint. More severely displaced fractures may require the use of skeletal traction, in which case we prefer to use a Schanz pin placed into the anterior superior iliac spine to reduce the disruption. The starting position for the initial screw is approximately 2.5 cm lateral to the posterior superior iliac spine. A small stab incision is made, and under image intensification the initial guidewire is placed superior to the first sacral foramen past the midline. We recommend that a second guide pin be placed between the first and second sacral foramina to help maintain the reduction during screw placement. The initial guide pin is then overdrilled across the sacroiliac joint and the lateral cortex is tapped, after which a partially threaded cancellous screw and a washer is passed over the pin. The screw should travel past the midline and usually has excellent purchase; it should help lag the sacrum to the ilium in a reduced position. We have used single-screw fixation in children’s sacroiliac joint disruptions with good success ( Fig. 30.18 ). If adequate screw purchase is not achieved, the screw position should be verified, and if the screw is in the correct position, a second screw should be placed between the first and second sacral foramina. Postoperatively, the patient can be partially weight bearing on the affected side, followed by full weight bearing after 6 weeks.

Complications

Nonorthopaedic complications are related to the associated injuries described in the preceding sections; these especially include complications involving the genitourinary and neurologic systems, hemorrhage, lacerations of the vagina or rectum, and possibly death. Urinary infections have been reported in 10% to 20% of patients, and pulmonary complications, including pneumonia, have occurred in 10% to 30% of patients. ^,

The multidisciplinary team must also consider screening and prophylaxis for a deep vein thrombosis (DVT). Pelvic fracture may be an additional risk factor for a DVT while admitted, particularly if a patient is intubated or requires prolonged immobilization. Prophylactic measures should include sequential compressive devices and/or physical therapy to implement a daily passive range of motion protocol. Although DVT have been reported and associated with pelvic fractures, the incidence has been reported to be 0.17%.

Complications related directly to pelvic and acetabular fractures include delayed union, nonunion, malunion, and sacroiliac joint pain. Complications, usually nonunion and premature closure of the triradiate cartilage, are most frequent after unstable, type IV fractures. Distortion of the pelvic ring also has been reported, but it does not appear to have a significant effect on the clinical outcome.

Anatomy

The development and growth of the acetabulum in children were described in a classic article by Ponseti. The acetabulum in childhood is referred to as the triradiate-acetabular cartilage complex, composed of epiphyseal growth plate cartilage of the ilium, ischium, and pubis; and articular cartilage ( Fig. 30.19 ). The acetabulum grows as a result of interstitial growth within the triradiate aspect of the cartilage complex, which causes the hip joint to expand and provide further depth. Secondary centers of ossification appear at puberty and include the following: the os acetabuli (os pubis or epiphysis of the pubis), which forms the anterior wall; the acetabular epiphysis (os ilium or epiphysis of the ilium), which forms the superior wall; and the seldom seen epiphysis of the ischium (os ischium) ( Table 30.5 ). Within the triradiate cartilage, the ilioischial flange is the most cellular and thus more susceptible to a clinical significant growth disturbance.

Mechanism of Injury

Like pelvic ring injuries, most displaced pediatric acetabular fractures occur as a result of a high energy trauma with reported injuries to the triradiate cartilage due to a direct injury. The most common mechanism when combined with a pelvic ring fracture is a motor vehicle collision (88%). Isolated pediatric acetabular fractures are more likely occur during sports or a fall. Lateral compressive forces through the femoral neck and head onto the acetabular surface can lead to damage to the triradiate cartilage and can lead to long-term arrest and developmental changes, causing future hip dysplasia .

Classification

Acetabular fractures in adults are best classified according to the original descriptions by Letournel. This classification scheme is based on five primary simple fracture patterns and five associated fracture types, which are is still used for skeletally mature acetabular fractures in adolescents. Acetabular fractures in children are best classified into four types.

Associated Injuries

Of all pelvic ring injuries, 58.6% to 68% are associated with acetabular fracture. Associated injuries with combined acetabular and pelvic ring fracture should be considered. Approximately 16% of isolated acetabular wall fractures occur with a concomitant hip dislocation. Other notes associating injuries include a proximal femur fracture or an epiphyseal separation of the proximal femoral physis.

Clinical Features

Clinical evaluation of a patient with an acetabular fracture is often the initial evaluation of a patient with a pelvic fracture. Because nondisplaced fractures of the triradiate cartilage can occur that are not obvious on early radiographs, a high suspicion for an acetabular physeal injury should warrant an MRI. Injuries to the triradiate cartilage can present with minimal displacement on CT scan, or decrease range of motion of the hip without evidence of a fracture on radiograph.

Radiographic Findings

Plain radiographs used to assess acetabular fractures include the oblique views described by Judet ( Fig. 30.20 ). The iliac oblique view shows the posterior column, anterior acetabular wall, and iliac wing. The obturator oblique view shows the anterior column, posterior wall, and obturator foramen ( Fig. 30.21 ). Careful inspection of the two oblique views and the AP pelvis view should allow classification of the acetabular wall fracture according to Letournel.

CT is used to assess acetabular fractures only after the fracture has been carefully evaluated and classified on plain radiographs. CT is performed to identify loose fragments and incongruities of the joint and to determine the size and displacement of the wall fracture. Although CT may be useful in older patients with mature pelvic and acetabular fracture patterns, plain radiographs provide information for diagnosis and management decisions in most pediatric pelvic fractures. High interobserver agreement has been demonstrated for fracture classification and treatment plan based on plain radiographs. In one study, plain radiographs predicted the need for operative treatment in all 62 patients, and CT affected the management plan in only 3%.

Normative values for the measurements of each triradiate cartilage have been noted and are useful in determining minimal displacement in suspected injury to the triradiate cartilage of the acetabulum ( Table 30.6 ).

Treatment

Acetabular fractures in children are generally treated nonoperatively, with approximately 25% requiring operative intervention. By contrast, almost all acetabular fractures in adults require operative intervention.

Nonsurgical treatment is indicated for children’s acetabular fractures when these fractures are minimally displaced (<2 mm) and for fracture-dislocations in which stable closed reduction of the femoral head results in minimal displacement of the fracture fragments. CT scan may be helpful in assessing displacement. This includes all type I and most type II fractures in which the fracture fragments are displaced less than 2 mm after hip joint reduction, as well as some type IV fractures in which reduction of the central hip dislocation results in fracture reduction to within 2 mm. All patients with less than 2 mm of displacement have good or excellent functional radiographic results.

No matter the classification of acetabular fracture, indications for operative management are not unlike adults. These include fractures with >2 mm displacement of the weight-bearing articular surface, hip joint instability, posterior wall fractures with >50% of the articular surface, or incarcerated fragments.

Types of Injuries

Type I Fractures

In type I fractures, the patient begins to ambulate on crutches without bearing weight whenever comfortable. Radiographs or CT scans, or both, should be obtained after the patient has been using crutches for a few days to ensure that the fracture fragments have not displaced. Progressive weight bearing is then started after 8 to 10 weeks.

Type II Fractures

Type II fractures are often associated with other pelvic ring fractures, which must be assessed and treated as discussed earlier. The acetabular fracture can generally be treated without surgery, usually with a period of bed rest and skin or skeletal traction. The period of bed rest is typically 4 weeks, followed by progressively increasing weight bearing, with an average time to full weight bearing of 10 weeks. Operative treatment of acetabular fractures of this type is relatively uncommon.

Type III Fractures

Type III fractures are treated similarly to those in adults with assessment of the fracture pattern. Application of skeletal traction can be used to restore articular congruity and further assess fracture characteristics. Operative intervention by a surgeon experienced in pelvic and acetabular fracture fixation is recommended and typically required for this fracture type. In the setting of an unstable patient or inefficient resources to proceed with operative intervention, skeletal traction may be considered if congruity of fracture fragments is within 2 mm.

Type IV Fractures

Type IV fractures with a central fracture-dislocation should be treated initially by skeletal traction in an attempt to reduce the dislocation and achieve an acceptable reduction. The few type IV fractures described in the literature have generally required operative intervention. Open reduction with stable internal fixation should be performed, although this may not improve the overall result.

Triradiate Cartilage Injuries

Although isolated triradiate cartilage injuries account for a small percentage of acetabular fractures in children, they must be recognized because these injuries can lead to significant progressive deformity ( Fig. 30.22 ). The acetabulum grows through interstitial growth within the triradiate cartilage, so interruption of this growth secondary to fracture results in a shallow acetabulum, similar to developmental dysplasia of the hip. Because acetabular deformity may develop and result in hip subluxation, any patient with a pelvic injury should be monitored clinically and radiographically for at least 1 year or until one can ensure normal acetabular growth.

Bucholz and coauthors classified triradiate cartilage injuries into two main patterns of injury based on the Salter-Harris classification. The first type, analogous to Salter-Harris type I or II injury, is a shear injury with central displacement of the distal portion of the acetabulum (see Fig. 30.22B and C); the prognosis for continued normal acetabular growth is favorable. The second type, analogous to a Salter-Harris type V injury, is often difficult to diagnose and generally has a poor prognosis, with premature closure of the triradiate cartilage. The degree of deformity depends on the age of the child at the time of injury; in no patient in their study did significant acetabular dysplasia develop when the injury occurred after 11 years of age. The diagnosis is confirmed by thin-section (2 to 3 mm) CT through the triradiate cartilage (see Fig. 30.22F ).

Premature physeal closure of the triradiate cartilage is treated by physeal bar resection and interposition of fat or wax. Very few cases have been reported in the literature, and the results have been mixed. We recommend consideration of physeal bar resection when the patient is younger than 12 years or significant growth remains.

Treatment Techniques

The operative approach to the acetabulum depends on the type of fracture present. The posterior column and posterior acetabular wall are best fixed through the Kocher-Langenbeck approach, and the anterior column and inner innominate bone are best approached through an ilioinguinal approach or a modified Stoppa approach. Both columns can be approached through an extended iliofemoral approach; however, this technique leads to the highest incidence of heterotopic ossification and the longest postoperative recovery period and is rarely used in children’s acetabular fractures.

The Kocher-Langenbeck approach requires the patient to be prone on a radiolucent operating table. The incision is begun lateral to the posterior superior iliac spine and extends to the posterior aspect of the greater trochanter and down the lateral aspect of the femoral shaft. The fascia lata is split in line with the femur, the gluteus maximus tendon is taken off its attachment to the femur, and the sciatic nerve is identified superficial to the quadratus femoris. The greater and lesser sciatic notches are then exposed by taking the piriformis and obturator internus tendons off the trochanter. Subperiosteal dissection is then carried out to expose the inferior aspect of the iliac wing, and capsulotomy is performed to expose the posterior aspect of the acetabulum and femoral head ( Fig. 30.23 ).

The ilioinguinal approach was first described by Letournel, and this classic description should be studied before using this approach. The patient is placed supine on the operating table. The incision begins at the midline approximately 3 to 4 cm above the pubis, continues to the anterior superior iliac spine, and follows the iliac crest. Subperiosteal dissection is then carried out along the iliac crest to expose the anterior sacroiliac joint and the internal iliac fossa. The external oblique aponeurosis is incised to expose the inguinal canal. The spermatic cord is bluntly dissected and isolated, and a Penrose drain is placed around it. The posterior aspect of the inguinal ligament is then incised to allow access to the psoas sheath, the retropubic space of Retzius, and the external aspect of the iliac vessels. A Penrose drain is next placed around the psoas and lateral cutaneous nerve of the thigh, and the iliopectineal fascia is divided. Another Penrose drain is placed around the external iliac vessels and lymphatics. The three windows of the ilioinguinal approach are now present ( Fig. 30.24 ). The first window is between the iliac fossa and the psoas muscle and gives access to the internal iliac fossa, the anterior sacroiliac joint, and the upper portion of the anterior column. The second window is between the psoas muscle and the iliac vessel and provides access to the pelvic brim from the anterior sacroiliac joint to the lateral extremity of the superior pubic ramus. The third window is medial to the iliac vessels and provides access to the symphysis pubis and the retropubic space of Retzius.

The modified Stoppa approach has been reported in adult literature, with limited series in pediatrics. The modified Stoppa approach allows for a more minimally invasive approach to anterior acetabular fractures with the potential to minimize risk to the triradiate cartilage. The extended iliofemoral approach is rarely necessary and can best be learned by studying Letournel’s original description.

Complications

Acetabular fractures are associated with complications early and late. Reported early complications include urinary or respiratory tract infection, pin tract infections, and superficial infection at the operative site. Late complications reported include premature closure of the triradiate cartilage requiring further operative treatment and extensive heterotopic ossification about the hip. In a recent series of 32 acetabular fractures in children, Kruppa and colleagues reported a 13.6% complication rate of development of hip dysplasia and leg length inequality of greater than 1.5 cm.

For References, see expertconsult.com .

Anatomy

The iliofemoral ligament, often referred to as the Y ligament of Bigelow, is the major ligamentous structure around the hip joint. It originates on the anterior inferior iliac spine, extends across the anterior aspect of the hip joint, and attaches to the femur at the anterior intertrochanteric line ( Fig. 30.25 ). The iliofemoral ligament limits hyperextension and lateral rotation of the hip joint and is the primary obstacle to reduction in posterior hip dislocations. The ischiofemoral ligament is located posteriorly and lies deep to the short external rotators, which provide additional stability. In a posterior dislocation of the hip, the ligamentum teres is avulsed; the posterior hip capsule is torn; a fragment of the posterior acetabular rim is often fractured; and the labrum may be avulsed or torn. The capsular tear may be at its attachment to the posterior labrum ^, or in its midsubstance. The short lateral rotator muscles—obturator internus, piriformis, obturator externus, and quadratus muscles—are either partially or completely torn along with the capsule. Structures and conditions that are known to block reduction include the following: the piriformis muscle, which may be displaced across the acetabulum; osteocartilaginous fragments; infolding of the labrum and capsule; and buttonholing of the femoral head through a small tear in the posterior capsule. ^{, , ,}

Anterior hip dislocations also tear the ligamentum teres and the anterior joint capsule. The muscles anterior to the hip joint may be stretched or partially torn. Rarely, the femoral nerve and artery are also damaged during a high-energy injury. ^,

Mechanism of Injury

Two mechanisms of injury result in a hip dislocation. In the young age group (<5 years), a trivial fall or slip may result in a hip dislocation because of the generalized joint laxity and soft cartilaginous acetabulum in this age group. ^{, ,} Non-accidental trauma should be considered in a traumatic hip dislocation in a young patient. In older patients, a hip dislocation is more often caused by higher-energy trauma (a contact athletic injury or a motor vehicle accident). It is important to obtain a thorough history because the mechanism of injury has prognostic implications; high-energy trauma injuries have a potentially worse outcome.

The typical posterior dislocation results from a posteriorly directed axial load applied to the distal end of the femur. It is often seen in motor vehicle accidents in which the patient is in the front seat during a head-on collision and the knee strikes the dashboard and pushes the femoral head posteriorly out of the acetabulum. This mechanism of injury often results in associated injuries, including hip, femoral shaft, distal femoral, patellar, or proximal tibial fractures. A front-seat passenger or driver who sustains these fractures in a motor vehicle accident should always be suspected of having a hip dislocation or subluxation with an associated acetabular injury.

Anterior hip dislocations are rare in children and result from an anteriorly directed force applied to the posterior aspect of the abducted and laterally rotated thigh. The femoral head is displaced forward and commonly lies external to the obturator foramen.

Central dislocations with fractures of the acetabulum result from a medially directed force on the greater trochanter. A fall from a height is the most common mechanism, followed by a motor vehicle accident in which the knee strikes the dashboard when the hip is extended and abducted.

Classification

Several classifications of hip dislocation exist. Because of the rarity of dislocations in children, however, no classification has been widely used. The simplest classification is based on the direction in which the femoral head is dislocated relative to the acetabulum. Most (75% to 90%) hip dislocations are posterior. ^{, , , ,} Posterior hip dislocations can be further subdivided according to the resting position of the femoral head: iliac, if the femoral head lies posteriorly and superiorly along the lateral aspect of the ilium; and ischial, if it lies adjacent to the greater sciatic notch. The remaining dislocations are anterior and are subdivided into obturator and pubic dislocations. A central hip dislocation is relatively rare in children and is associated with fracture of the acetabulum.

Hip dislocations in children are associated with acetabular or proximal femoral fractures far less frequently than in adults. The incidence of associated fractures in children ranges from 4% to 18%. ^{, ,} The Stewart-Milford classification is the most commonly used classification for hip fracture-dislocations.

Physeal fracture of the proximal femoral epiphysis may occur in conjunction with a hip dislocation. Displacement of the epiphysis may be noted at initial evaluation or after attempted reduction if a nondisplaced physeal fracture is unrecognized. These fracture-dislocations have been reported in the periadolescent age group and are uniformly associated with avascular necrosis (AVN) of the femoral epiphysis. ^{, ,}

Acetabular fractures should be classified individually to allow standard preoperative treatment planning to be carried out (see the previous discussion of pelvic and acetabular fractures).

Clinical Features

A child with an acute hip dislocation is typically in severe pain, and any attempted motion of the affected hip exacerbates the pain. The position of the limb is characteristic of the type of hip dislocation. In a posterior hip dislocation the involved thigh is held flexed and adducted and in a internally rotated position ( Fig. 30.26A ). The limb appears shorter than the contralateral limb, and the femoral head can be palpated posteriorly. In anterior dislocations the leg is held in abduction, externally rotated, and some flexion (see Fig. 30.26B ). Fullness is noted in the region of the obturator foramen, where the femoral head can be palpated, and the extremity may appear longer than the other side. In central hip dislocations the leg does not rest in a characteristic position and leg length is similar to that of the opposite leg. Some narrowing of the pelvic width may occur as a result of central displacement of the affected hip.

A thorough neurologic examination of the affected extremity should be performed both prior to and following a reduction, with careful evaluation of sciatic nerve function in posterior dislocations and femoral nerve function in anterior dislocations. The peripheral pulses, including the posterior tibial and dorsalis pedis, should be palpated, and a thorough examination should be performed to assess for other injuries, especially ipsilateral lower extremity fractures and soft tissue knee injuries. ^a

a References , , , , , , .

Radiographic Findings

An AP pelvic radiograph should be routinely obtained with any suspected hip injury or dislocation, to rule out other fractures ( Fig. 30.27A ). Although most hip dislocations are thought to maintain a dislocated position, spontaneously reduced dislocations with subsequent evaluation for pain secondary to interposed tissues have been reported. A child or adolescent with hip pain after injury and radiographs demonstrating asymmetric widening of the hip joints should be evaluated with further imaging techniques such as a CT or MRI. ^, We recommend use of an MRI in all skeletally immature hip dislocations following a reduction based on the risk of chondral and osteochondral injury not visible on x-ray, and to minimize radiation exposure. ^{, ,}

Oblique (Judet) views and CT scans should be obtained when an associated acetabular fracture is suspected. Isolated radiographs of the hip joint should be obtained to exclude other fractures before attempts are made to reduce the hip dislocation when a femoral head or femoral neck fracture is seen on the initial AP pelvic film. A fluoroscopic examination before reduction may be considered in the periadolescent age group to evaluate for evidence of epiphyseal motion secondary to unrecognized physeal fracture. After reduction of the hip dislocation, an AP pelvic radiograph should be carefully evaluated to confirm concentric reduction ( Fig. 30.28 ). A small “fleck” visualized on either an AP pelvis x-ray or a CT may represent a posterior labrum osteochondral avulsion. MRI has been reported to be useful to assess unossified acetabular rim fractures in the uncommon setting of postreduction instability without a visible fracture. Based on our experience treating large chondral fractures not visible on x-ray following a traumatic hip dislocation in a skeletally immature patient, we have begun to obtain MRI images on all skeletally immature patients to further assess chondral, osteochondral, and labral injuries, and, when possible, the vascularity of the femoral head with a perfusion MRI study. An arteriogram should be obtained in any child in whom the clinical findings or Doppler studies indicate a femoral arterial injury.

Treatment

Hip dislocations should be treated on an urgent basis with prompt, immediate reduction after a thorough physical examination and evaluation of the plain radiographs. Closed reduction should be attempted while the patient is under general anesthesia in the operating room if the procedure can be performed without delay, or in the emergency department with the patient under conscious sedation. The method and duration of immobilization after reduction have not been agreed on, although some form of protection of the reduction should be used.

Closed Reduction

Posterior Dislocation

Closed reduction of a posterior dislocation can be achieved by using the Bigelow, Allis, or Stimson methods, all of which rely on flexion of the hip joint to relax the iliofemoral ligament. All methods require adequate sedation of the patient. Care must be taken to reduce the likelihood of iatrogenic injury to the proximal femoral physis.

The easiest, most common, and most effective treatment is that described by Allis ( Fig. 30.29 ). The patient is placed supine, and an assistant stabilizes the pelvis by applying direct pressure over the anterior superior iliac spine. The hip and knee are then flexed 90 degrees with the thigh in slight adduction and medial rotation. The surgeon then places a forearm behind the patient’s knee and leg and applies an anteriorly directed force to release the femoral head from behind the posterior lip of the acetabulum. If soft tissue resistance is felt, the medial rotation and hip adduction are increased in an effort to relax the hip joint capsule further, and closed reduction is again attempted.

In the circumduction method of Bigelow, an assistant applies countertraction on the anterior superior iliac spine while the surgeon grasps the affected limb at the ankle with one hand and places the opposite forearm behind the patient’s knee ( Fig. 30.30 ). The initial maneuver is to flex the adducted and medially rotated thigh 90 degrees while longitudinal traction is applied in line with the deformity. This will relax the Y ligament and bring the femoral head near the posterior rim of the acetabulum. The femoral head is then freed from the rotator muscles by gently rotating the thigh back and forth. Finally, the femoral head is levered into the acetabulum by gentle abduction, lateral rotation, and extension of the hip. Manipulation should always be gentle to prevent rupture of the Y ligament or damage to the sciatic nerve. The prone position is required for the Stimson technique, which is difficult to perform in a larger child but can be used in a younger patient ( Fig. 30.31 ).

Anterior Dislocation

To reduce an anterior dislocation of the hip, a modification of the Allis technique entails initially flexing the knee to relax the hamstrings while the hip is fully abducted and flexed to 90 degrees ( Fig. 30.32 ). Traction should be applied directly in line with the longitudinal axis of the femur while an assistant applies posterior pressure on the anteriorly dislocated femoral head. The surgeon then adducts the hip, with the patient’s thigh used as the lever, to reduce the femoral head into the acetabulum. The hip can be medially rotated as it is adducted to achieve reduction.

Central Dislocation

Central dislocations require skeletal traction through a distal femoral pin to reduce the femoral head to its anatomic position. Because a central dislocation is associated with an acetabular fracture, which is often comminuted, the medially displaced femoral head must be initially reduced to its anatomic position. This is best accomplished with a skeletal traction pin (Schanz pin placed in a lateromedial direction or a skeletal traction pin placed in the AP direction) in the greater trochanter. Lateral traction can be applied to initially reduce the central dislocation and can then be removed if the reduction is stable, or it can remain for up to 2 to 3 weeks. The distal skeletal traction is maintained for a total of 3 to 4 weeks, with some active range of motion of the hip allowed to promote molding of the acetabulum.

Open Reduction

The indications for open reduction of a dislocated hip are: failed closed reduction, nonconcentric closed reduction, or a dislocation associated with a displaced femoral head or neck osteochondral or chondral fracture, or an acetabular fracture. The surgical approach depends on the direction of the hip dislocation and the complexity of the associated injuries: a posterior approach may be performed for posterior dislocations or an anterior approach used for anterior dislocations. A surgical hip dislocation may also be an option for reduction and to treat associated intraarticular pathology.

The goals of surgical intervention are to clear the obstacles preventing reduction of the hip (piriformis tendon, hip capsule), identify objects preventing concentric reduction (inverted limbus, osteocartilaginous loose bodies), anatomically fix any acetabular or femoral head fractures, and repair the soft tissue envelope. Clinical series suggest that as many as 25% of patients may require open reduction. ^,

Posterior Approach

A standard posterior approach (Southern or Moore) to the hip is used ( Fig. 30.33 ). The sciatic nerve should be identified visually and followed both proximally and distally, especially when nerve injury has been identified on the preoperative physical examination. The remaining soft tissue structures should then be inspected and all torn muscles tagged with suture to allow proper closure at completion of the procedure. The short external rotators should be divided 1 cm from their insertion. The femoral head is often protruding through a tear in the posterior capsule, and care should be taken to avoid injuring the articular cartilage at that point. The capsule should be incised to allow complete inspection of the labrum, the posterior wall of the acetabulum, and the articular surfaces of the acetabulum and femoral head. Subluxation or dislocation of the femoral head should be performed to allow good visualization; it is often achieved by means of skeletal traction applied through a Schanz pin placed in the greater trochanter. The joint is irrigated, and any osteocartilaginous debris is removed. Posterior rim fractures should be internally fixed with screws in a young child, and a 3.5-mm pelvic reconstruction plate should be used in an adolescent. Labral avulsions are repaired by fixing the labrum down to the posterior rim of the acetabulum; the posterior capsule should be repaired (see Fig. 30.33E ).

Anterior Approach

An anterior approach for an anterior hip dislocation can be either a direct anterior (Smith-Petersen) or an anterolateral (Watson-Jones) approach. The literature on surgical intervention for anterior dislocations is sparse, ^, however, the goals of surgical treatment remain the same and should be kept in mind when operative intervention is needed.

Surgical Hip Dislocation

A surgical hip dislocation, our preferred technique, may be considered by experienced surgeons for improved visualization of the hip or when treating osteochondral fractures of the acetabulum or femoral head. ^, A surgical hip dislocation also allows for improved exposure of chondral injury, for an osteochondral fixation, and a labral repair when necessary ( Fig 30.34 ). In our series, eleven consecutive surgical hip dislocations were performed follow a noncentric reduction after a closed reduction from a traumatic posterior hip dislocation. Most of the intraarticular structures preventing concentric reduction stemmed from acetabular labral and femoral osteochondral fractures. There has been one reported case of osteonecrosis following a surgical hip dislocation following a traumatic hip dislocation to date, indicating that this is a safe option.

Hip Arthroscopy

Hip arthroscopy may be considered to address labral pathology or to assist with a nonconcentric reduction when a chondral or osteochondral fracture is not suspected. In the acute setting, hip arthroscopy should only be considered if soft tissue is enfolded (i.e., posterior capsular labral soft tissue complex) to prevent a concentric reduction. Due to extensive soft tissue injury, the surgeon must be mindful of fluid pressure extravasation in the retroperitoneal space during arthroscopy, as abdominal compartment syndrome has been reported following hip arthroscopy. ^{, , ,} When a concentric reduction is obtained, we recommend treatment of labral pathology in a subacute or delayed fashion if symptomatic.

Complications

The most common complications after a traumatic hip dislocation in children are AVN of the femoral head, sciatic nerve injury, recurrence of the hip dislocation, late degenerative arthritis, and rarely, femoral arterial injury in anterior dislocations.

Avascular Necrosis

The most frequent complication after a posterior traumatic hip dislocation in children is AVN of the femoral head, with a reported incidence of between 8% and 18%. ^{, , , ,} The most important factors predisposing to the development of AVN are older age (>6 years), severe trauma, prereduction or perireduction epiphyseal separation, and a delay of more than 6 hours from the time of injury to the time of reduction ( Fig. 30.35 ). Although radiographic changes can be seen as early as 3 months after injury, AVN can develop up to 2 years later. Therefore, serial radiographs should be obtained for at least 2 years after the original dislocation.

Anatomy

The proximal femur consists of a single physis at birth that later separates into two distinct centers of ossification—the capital epiphysis and the trochanteric apophysis. Ossification of the femoral epiphysis occurs between 4 and 6 months of age, and the ossific nucleus ( Fig. 30.36 ) of the greater trochanter appears at 4 years. The femoral neck–shaft angle is 135 degrees at birth, increases to approximately 145 degrees by 1 to 3 years of age, and gradually matures to an average angle of 130 degrees at skeletal maturity. ^{, ,} Femoral anteversion is approximately 30 degrees at birth and decreases to an average of 10.4 degrees at skeletal maturity. ^, The trochanteric physis closes between 16 and 18 years and the proximal femoral physis at approximately 18 years. Growth arrest of the proximal femoral physis before skeletal maturity may result in an abnormal neck–shaft angle, femoral anteversion, and a reduced articulotrochanteric distance ( Fig. 30.37 ). In addition, because the proximal femoral physis contributes approximately 15% of the growth of the entire extremity, limb length discrepancy may occur, the severity of which depends on the age of the patient at the time of injury.

Because of the high incidence of AVN of the femoral head, it is important to understand the vascular anatomy of the proximal femur. It has been extensively studied by Chung, Ogden, and Trueta. The blood supply of the proximal femur comes from two major branches of the profunda femoris artery—the medial and lateral circumflex arteries, which originate at the level of the tendinous portion of the iliopsoas muscle ( Fig. 30.38 ). The lateral circumflex artery travels posterior to the femoral neck, and the medial circumflex artery travels anterior to it. The transverse branch of the lateral circumflex artery divides at the anterolateral border of the intertrochanteric line and gives off branches that penetrate the lateral and anterolateral portions of the greater trochanter. Until the age of 5 to 6 months this branch also supplies much of the anterior portion of the proximal femoral epiphysis and physis.

The major blood supply to the proximal femur comes from the medial circumflex artery, which travels posterior to the iliopsoas tendon and then to the medial side of the proximal femur between the insertion of the inferomedial capsule and the lesser trochanter. Two major branches of the medial circumflex artery are then given off: the posterior inferior branch, which travels along the inferior margin of the posterior neck, and the posterior superior branch, which travels along the superior margin.

At birth the lateral circumflex artery supplies the anterolateral growth plate, the major aspect of the greater trochanter, and the anteromedial aspect of the femoral head. The medial circumflex artery branches to provide blood to the posteromedial proximal epiphysis, the posterior physis, and the posterior aspect of the greater trochanter. The artery of the ligamentum teres supplies a small area of the medial femoral head. Blood vessels, which cross the physis at birth, gradually disappear by the age of 15 to 18 months, at which time no vessels are observed crossing the growth plate.

By the age of 3 years the contribution of the lateral circumflex vessel to the blood supply of the proximal femur diminishes and the entire blood supply of the proximal femoral epiphysis and physis comes from the lateral epiphyseal vessels, branches derived from the medial circumflex artery ( Fig. 30.39 ). The posterosuperior and posteroinferior vessels were thought to have prominent roles in the blood supply to the femoral head by Ogden, although Trueta and Morgan thought that the lateral cervical ascending artery (posterosuperior branch) played a more significant role. These vessels lie external to the joint capsule at the level of the intertrochanteric line and then traverse the capsule and travel proximally within the retinacular folds. Very few vessels supplying the femoral head travel within the capsule, and therefore a capsulotomy incision should not compromise the vascularity of the femoral head. This arrangement of the blood supply to the femoral head persists into adulthood. The artery of the ligamentum teres, a branch of the obturator (80%) or the medial circumflex (20%), provides approximately 20% of the blood supply to the femoral head beginning at approximately 8 years of age and is maintained into adulthood. ^,

Mechanism of Injury

Hip fractures in children are most frequently the result of high-energy trauma (a fall from a height, a motor vehicle accident, or a fall from a bicycle). Such mechanisms account for approximately 85% to 90% of all fractures. ^c

c References , , , , , , , , .

Because of the significant energy required to produce these fractures in children, associated major injuries are seen in up to 30% of cases. ^, Intraabdominal or intrapelvic visceral injuries and head injuries are the most common associated injuries. Other musculoskeletal injuries seen less often include hip dislocations and pelvic and femoral shaft fractures. ^,

A few patients sustain hip fractures from trivial trauma, often associated with a pathologic lesion in the area of the fracture. Pathologic fractures of the hip often have prodromal symptoms prior to the fracture. The most common preexisting conditions include a unicameral or aneurysmal bone cyst, osteogenesis imperfecta, fibrous dysplasia, and myelomeningocele. ^{, , ,}

Finally, child abuse may be a cause of hip fractures in children younger than 12 months. ^, If suspected, a thorough exam should be followed by consideration of a skeletal survey. Local or hospital authorities should be contacted for an evaluation for nonaccidental trauma.

Classification

Fractures of the hip in children are classified into four types based on the anatomic location of the fracture, as described by Delbet and later popularized by Colonna ( Fig. 30.40 ):

• Type I: Transepiphyseal—acute traumatic separation of a previously normal physis. This type of fracture accounts for less than 10% of all children’s hip fractures. In 13 reported series, 43 (8%) of 511 hip fractures in children were type I. ^d

  d References , , , , , , , , , , .

  Anatomically, these fractures are similar to the type I physeal injury of Salter and Harris and can be distinguished from a slipped capital femoral epiphysis (SCFE) by the younger age of the patient (8 to 9 years), the usually sudden onset of pain secondary to severe trauma, and radiographs showing a more displaced acute separation of the physis. This injury predominantly occurs in two age groups: young infants (<2 years) ^{, , ,} and children 5 to 10 years of age. ^, In a newborn it is known as proximal femoral epiphysiolysis and follows breech delivery; it may be mistaken for congenital dislocation of the hip. The injury is usually recognized late (>2 weeks), after the formation of abundant callus. ^, It has also been described in adolescent patients after attempted closed reduction of a posterior hip dislocation. ^, The mechanism of injury is often being struck by a car or a falling from a height, but it has also been reported in victims of child abuse ^, and during difficult labor. It is associated with femoral head dislocation in approximately 50% of cases. ^{, , ,} Associated injuries occur in up to 60% of cases, with pelvic fractures the most common. The outcomes of treatment are relatively poor, and the reported incidence of AVN of the femoral head is 20% to 100%. ^{, , ,}

• Type II: Transcervical—fracture through the midportion of the femoral neck. This is the most common fracture type and accounts for 40% to 50% of hip fractures. In the literature, 229 (45%) of 511 hip fractures in children were type II. ^e Of these fractures, 70% to 80% are displaced when initially seen. The most common complication is AVN, which was historically reported to occur in up to 50% of patients. ^{, , ,} However, more recent studies that relied on more aggressive treatment, including evacuation of intracapsular hematoma, reported a significant reduction in the incidence of AVN. ^{, ,} The best predictor of AVN is displacement of the fracture at the time of injury. ^, Other complications, including loss of reduction, malunion, nonunion, varus deformity, and premature epiphyseal closure, result in relatively poor outcomes when compared with the outcomes of types III and IV fractures.

• Type III: Cervicotrochanteric—fracture through the base of the femoral neck. The reported incidence is between 25% and 35%. Of 511 hip fractures, 171 (33%) were type III. ^f

  f References , , , , , , , , , , .

  AVN occurs in approximately 20% to 25% of cases and is related to the amount of displacement at the time of injury.

• Type IV: Pertrochanteric or intertrochanteric—fracture between the greater and lesser trochanters. The reported incidence is between 6% and 15%. Of 511 hip fractures, 68 (13%) were type IV. ^g

  g References , , , , , , , , , , .

  AVN occurs infrequently (<10%), and these fractures have the best overall outcome.

Hip fractures that do not fit into the Delbet classification include fractures of the proximal metaphysis in newborns and stress fractures. Proximal metaphyseal fractures are often confused with dislocation of the hip because the capital femoral and greater trochanteric epiphyses are not yet ossified ( Fig. 30.41 ). Stress fractures of the femoral neck have been reported in fewer than 20 cases in the literature; the child has a history of a minor injury, vague hip pain, and no sudden change in activity as seen in adults. ^{, , , ,} The fracture is often missed on initial evaluation, which may lead to displacement requiring operative intervention ( Fig. 30.42 ). ^,

Clinical Features

The patient is initially seen after a severe traumatic event with complaints of severe pain in the hip. The history should include the mechanism of injury and a description of other areas of pain. Because of the severity of the hip pain, the patient may not provide a good description of other painful areas, and therefore the examiner must take care to rule out associated injuries. Conversely, other severe injuries can obscure the diagnosis of a hip fracture. Undisplaced hip fractures and stress fractures, which occur in approximately 30% of cases, ^, may not produce severe pain. The patient may be ambulating at the time of evaluation after a “twisting” or “sprain” of the hip from a slip or athletic mishap. ^{, , ,}

On physical examination a patient with a displaced hip fracture holds the injured limb externally rotated and slightly adducted, and the limb appears shortened. The patient is in severe pain and unable to move the limb actively. Local tenderness is elicited on palpation and is most severe posteriorly over the femoral neck. Passive motion of the extremity is markedly restricted, especially with flexion, abduction, and medial rotation.

In a nondisplaced or impacted fracture the hip examination may not be remarkable, with very mild discomfort elicited during passive range of motion of the extremity. In addition, the patient may be able to ambulate with very little pain. A careful, detailed history, physical examination, and radiographic evaluation are important in these patients to avoid missing the diagnosis.

Radiographic Findings

Radiographic evaluation consists of AP and lateral images of the hip. The radiographs should be analyzed for the type of fracture, the direction of the fracture line, the amount of displacement, the degree of displacement and angulation, and the location of the femoral epiphysis. Comparison views of the other hip may assist the surgeon in determining whether a nondisplaced fracture of the femoral neck is present or, more importantly, to view the patient baseline neck-shaft angle. Such a determination is best done by inspecting the proximal end of the femur for any disruption in the normal trabecular pattern.

MRI is the best imaging modality for a nondisplaced or stress fracture of the femoral neck because it provides greater accuracy, earlier diagnosis, and shorter hospital stay, with no exposure to radiation. ^{, , ,} MRI will demonstrate decreased signal on a spin-echo T1-weighted image and a correspondingly increased signal as a result of edema or bleeding on T2-weighted images. An additional advantage of MRI over other imaging modalities is that supplemental information can be obtained, including femoral head viability and the presence of associated bone cysts indicating pathologic bone.

Treatment

Improvements in surgical techniques and more aggressive treatment have resulted in improved outcomes in children’s hip fractures. ^, Results in young children (<8 years) with nondisplaced fractures or type III or IV fractures are better than those in older children with displaced type I or II fractures. Major considerations in treating all pediatric proximal femur fractures involve minimizing complications, including AVN, loss of reduction, and nonunion. The surgeon must consider open versus closed reduction, timing of treatment, and addressing the possible tense hemarthrosis causing a tamponade effect on the epiphyseal vessels.

The goals of treatment of children’s hip fractures are to achieve anatomic reduction and provide stability to the fracture fragments. In general, these goals are best achieved in the operating room, with fracture reduction performed under fluoroscopic guidance and fracture stabilization achieved with internal fixation. An open reduction should be considered, and prepared for, if anatomic reduction cannot be achieved with a closed reduction. A review of 22 displaced femoral neck fractures emphasized the importance of an open reduction in improving anatomic reduction and minimizing complications. ^, Other studies have also confirmed that lower complication rates, including loss of reduction, nonunion, and AVN, are seen with open treatment as compared to closed reduction.

Timing of treatment of femoral neck fractures remains an important consideration. ^, Although recent evidence has not definitively suggested the need for urgent treatment, ^, surgically addressing a pediatric femoral neck fracture and decompressing the traumatic hemarthrosis should occur as soon as a skilled orthopaedic surgical team is available. We recommend treating these within 24 hours; however, a recent systematic review did not demonstrate a significant difference in the rate of osteonecrosis between those treated prior to or after 24 hours from injury.

Even though the mode of treatment has not been thought to affect the incidence of AVN, growing evidence indicates decompressive hip arthrotomy reduces this risk. ^{, , , ,} Studies of the frequency of AVN after hip decompression reported mixed results, with some showing a decreased frequency and others showing no difference. Although the data are not conclusive, they do suggest that hip decompression helps lower the incidence of AVN, is relatively easy to perform, and is associated with minimal complications. Therefore we recommend capsular decompression at the time of initial treatment. This may be performed via needle aspiration following a closed reduction, or when a lateral approach is made, through an anterior capsulotomy with a Freer or Cobb elevator along the anterior femoral neck. The procedure should be done at the completion of reduction and fixation to minimize the reaccumulation of fracture hematoma.

Type II: Transcervical Fractures

We recommend that all transcervical fractures (including nondisplaced fractures) in children of all ages be treated by anatomic stable internal fixation to avoid loss of reduction and subsequent malunion, delayed union, or nonunion ( Fig. 30.43 ). These complications are much more common when fractures are stabilized by closed reduction and external immobilization alone. ^{, ,} Anatomic reduction must be achieved to help prevent nonunion, and although not proven, it may diminish the risk for development of AVN. Gentle closed reduction should be attempted under fluoroscopic guidance. The closed reduction maneuver was described in the 1890s by Whitman, who believed that anatomic alignment was mandatory to prevent future deformity. ^, The reduction consists of fully abducting the normal hip to stabilize the pelvis, followed by progressive abduction of the extended affected hip. The surgeon then places downward pressure on the greater trochanter and uses the upper border of the acetabular rim as a fulcrum to restore the normal relationship of the proximal femur while the hip is abducted ( Fig. 30.44 ). During abduction of the hip, the extremity is internally rotated to 20 to 30 degrees to complete the reduction maneuver. Once reduction is achieved, the extremity should be slowly adducted to allow placement of internal fixation through a lateral approach.

If closed manipulation fails to achieve anatomic reduction, open reduction through an anterior, anterolateral, or direct lateral approach must be performed. A traditional Smith-Peterson anterior approach to the hip is valuable option, provides greater exposure, and often requires a secondary incision. Once reduction is achieved, the fracture should be stabilized with threaded Kirschner wires in a young child and cannulated screws in an older child. Internal fixation devices should be kept distal to the physis; however, fracture stability is of prime importance and should not be compromised in an attempt to avoid the growth plate ( Fig. 30.45 ). In an older child a minimum of two screws should be placed parallel to one another and with screw threads in the proximal fracture fragment, producing compression across the fracture site either with a lag-screw technique or with partially threaded screws. To avoid fracture displacement, we recommend having two guidewires in place while the third guidewire is overdrilled, tapped, and then used as a guide for screw placement.

Some centers have begun to use locked proximal femoral implants for the management of femoral neck fractures. Although criticisms may be made because the implants may create distraction and reduce impaction of the fracture site, thus theoretically increasing the nonunion risk, benefits include a reduced risk of varus collapse and potentially less need for cast immobilization in older patients.

Cast immobilization in a one-and-one-half-hip spica cast may be considered postoperatively for 6 to 12 weeks until good healing callus is seen.

Type III: Cervicotrochanteric Fractures

Although type III fractures have a better overall outcome than do type II fractures, a malunited fracture has equally poor results. ^,

We recommend that a displaced fracture be treated by closed reduction and internal fixation or ORIF in all age groups. Nondisplaced fractures in an older child (>6 years) should also be treated by internal fixation ( Fig. 30.46 ). Although some surgeons have recommended closed reduction and abduction spica casting without internal fixation, maintenance of the reduction relies on the position of the extremity and the molding of the cast. In most cases we prefer the stability of internal fixation. In addition, because of the distal location of this fracture relative to the physis, internal fixation with cannulated screws or Kirschner wires is technically easier than in a type II fracture and much less likely to require crossing of the physis to achieve fixation. However, the distal location of the fracture may not afford good purchase for cannulated screws, and the results could be loss of reduction and subsequent varus. If cannulated screws alone are used for fixation, we recommend hip spica casting to supplement it. As in type II fractures, the use of locked proximal femoral plates or screw and side plate constructs may reduce the risk of varus collapse.

Type IV: Pertrochanteric or Intertrochanteric Fractures

These fractures typically have the lowest risk of long-term complications and can be treated with cast immobilization alone in certain patients. As in type II and III fractures, closed reduction with internal fixation is the treatment of choice for a displaced fracture in any age group and for a nondisplaced fracture in an older child ( Fig. 30.47 ).

Complications

Hip fractures in children are associated with a high incidence of complications, especially with displaced fractures and older children. ^{, , ,} The incidence of each complication has diminished with more aggressive operative management, including prompt closed or open reduction, stable internal fixation that avoids the physis, and external immobilization. Common complications in children’s hip fractures include AVN, coxa vara, nonunion, premature physeal closure, and infection.

Avascular Necrosis

AVN is the most common and most devastating complication associated with hip fractures in children ( Fig. 30.48 ). AVN is the principal cause of poor results in children’s hip fractures. Historically, the incidence of AVN has been reported to be 100%, 50%, 25%, and 15% for types I, II, III, and IV fractures, respectively, with an overall incidence of 43%. In a more recent literature review, the incidence of AVN was lower: 38%, 28%, 18%, and 5% for types I, II, III, and IV fractures, respectively and an overall rate of 29%. ^, AVN of the femoral head is thought to result from disruption or compromise of the blood supply of the femoral head at the time of the initial trauma (displacement of the fracture) and potentially from the tamponade effect of the hip hemarthrosis.

Predisposing Factors

Several studies found the following risk factors for AVN: fracture displacement, which is the most important factor; the presence of a type I or II fracture; and a fracture in an older child (>12 years). ⁱ

i References , , , , , .

Although early reduction (within 24 hours) with fixation improves the overall outcome of hip fractures in adults, few studies have directly compared early and late treatment in children.

Clinical Features and Radiographic Findings

Symptoms of AVN may occur early, with complaints of groin pain. Radiographic evidence of AVN can be seen as early as 2 months after injury; such evidence is generally present within 1 year of injury ( Fig. 30.49 ). ^, The median time to presentation is 7.8 months. Radiographs may demonstrate osteopenia of the femoral head, followed later by sclerosis, fragmentation, and often collapse and deformity. MRI is the most sensitive test to confirm the diagnosis and also defines the extent of femoral head and neck involvement. Radioisotope scanning shows decreased uptake in the femoral head or neck (or both) and is useful in a hip that has stainless steel internal fixation. ^,

Patterns

Three patterns of AVN have been described by Ratliff ( Fig. 30.50 ).

Type I AVN is characterized by severe diffuse necrosis totally involving the femoral head and the proximal fragment of the femoral neck ( Fig. 30.51 ). The femoral head necrosis is accompanied by various degrees of collapse of the femoral head, from segmental necrosis with minimal collapse to diffuse complete collapse with subluxation. Type I AVN results from interruption of the lateral epiphyseal and metaphyseal vessels. This is the most common pattern of AVN; it accounts for more than 50% of cases and has the worst prognosis.

Type II AVN is characterized by more localized necrotic changes, often in the anterosuperior aspect of the femoral head, with little collapse ( Fig. 30.52 ). It is usually caused by interruption of the lateral epiphyseal vessels before entrance into the epiphysis. This type is seen in approximately 25% of cases and has a better prognosis than does type I AVN.

Type III AVN is characterized by sclerosis from the fracture line of the femoral neck to the physis, with sparing of the femoral head ( Fig. 30.53 ). It accounts for 25% of cases of AVN and has the best results.

Treatment and Prognosis

In general, AVN after hip fractures in children results in poor outcomes in up to 60% of cases.

Treatment of AVN has been relatively unsuccessful, and some investigators have suggested that treatment does not affect the natural history. Because limited data are available on the treatment of AVN after hip fractures in children, defining the superiority of one treatment modality over others is difficult. ^,

The goals of treatment are to preserve the functional range of hip motion, maintain containment of the femoral head within the acetabulum, and preserve as much femoral head viability as possible. In general, treatment of AVN should begin at the onset of symptoms and should entail partial weight bearing or non–weight bearing until the painful symptoms resolve.

Operative treatment has resulted in poor outcomes principally because of selection bias; the most severe cases of AVN have undergone operative treatment. When AVN is first recognized, the initial step, if the fracture has healed, is removal of internal fixation devices to prevent penetration of the hardware into the joint. Further operative treatment options include intertrochanteric osteotomy (usually valgus) to place viable head in the weight-bearing zone, capsulotomy, and arthrodesis.

We recommend partial weight bearing or non–weight bearing on the involved extremity at the first signs and symptoms of AVN until revascularization is complete and the painful symptoms have resolved. This may warrant a prolonged period of immobilization. If femoral head necrosis is associated with severe symptoms and subluxation, intertrochanteric osteotomy to place more viable head in the weight-bearing zone or arthrodesis is recommended ( Fig. 30.54 ). In general, we do not recommend cup arthroplasty or total hip arthroplasty in an adolescent with AVN because of the relatively short life span of these prostheses in a young, active patient.

Some of the theories of management of idiopathic AVN (Legg-Calvé-Perthes) may be included in traumatic cases. Early imaging with MRI to determine the extent of necrosis and to follow revascularization may be considered. In addition, core decompression procedures may be considered before collapse in hopes of stimulating revascularization. Currently scant literature supports this use; however, clinically many surgeons have attempted this treatment with variably reported success.

Coxa Vara

Coxa vara may have four main causes: malreduction, in which the fracture is left in a varus position; loss of reduction because of inadequate fracture stabilization; delayed union or nonunion; and premature closure of the proximal femoral physis with overgrowth of the greater trochanter. Coxa vara occurs in 10% to 32% of cases, depending on the type of treatment. ^j

j References , , , , , , .

Closed reduction and external immobilization with abduction casting result in the highest incidence of coxa vara, most often caused by loss of reduction. Although closed reduction and internal fixation can result in coxa vara, the varus deformity tends to be mild when compared with that in patients treated by closed reduction and casting. Some surgeons have suggested that the obliquity of the fracture line (a Pauwels angle >50 degrees) results in fracture instability and predisposes to varus deformity. Some remodeling occurs with milder deformity, especially in a younger child. However, a neck–shaft angle of less than 100 degrees is associated with a poor outcome, and such a deformity has little ability to remodel, even in a young child.

Coxa vara deformity is best prevented by anatomic reduction and rigid internal fixation followed by external immobilization in most cases. To lessen the risk for premature physeal closure and subsequent coxa vara, internal fixation devices should avoid the growth plate as long as good screw purchase can be achieved. We recommend valgus osteotomy with fixed angle device (i.e., blade plate) in a child with a neck–shaft angle of less than 110 degrees or when reduction is lost ( Fig. 30.55 ).

Nonunion

The incidence of nonunion varies between 6.5% and 12.5% and appears to be related to the method of treatment. ^{, , ,} Higher rates of nonunion were reported in various series of patients in which most were treated by external immobilization ^, than in more recent series in which internal fixation was used. ^, Additional factors associated with nonunion include poor reduction, distraction of the fracture fragments at the time of internal fixation, and a Pauwels angle greater than 60 degrees. Nonunion can lead to coxa vara and can predispose to other complications such as AVN and premature physeal arrest; the results are ultimately poor when an established nonunion occurs. Therefore, prevention by means of anatomic reduction, rigid internal fixation, and external immobilization is important.

Nonunion should be treated when it is diagnosed to prevent further complications. In a child younger than 10 years, we recommend autogenous bone grafting and rigid internal fixation, with screws placed in lag-type fashion to gain compression across the fracture site. A subtrochanteric valgus osteotomy should be performed as described by Pauwels in an older child or in any child with a Pauwels angle greater than 60 degrees or when unreducible coxa vara is present ( Fig. 30.56 ). The goal of valgus osteotomy is to alter the plane of the fracture to produce compressive loads across the fracture site for enhancement of healing. Preoperative planning should be performed to restore a normal neck–shaft angle, which generally requires removing an approximately 25-degree laterally based wedge with the osteotomy placed just superior to the lesser trochanter, followed by internal fixation.

Anatomy and Development

The femur first appears during the fourth week of gestation as a condensation of mesenchymal tissue. By the eighth week, enchondral ossification has begun and growth is rapid. The primary ossification center is the femoral shaft, with ossification of the secondary centers beginning in the upper epiphysis at 6 months as a single center of ossification that later becomes the femoral head and the greater trochanter. The distal secondary center of ossification develops during the seventh fetal month. The femoral head ossifies at approximately 4 to 5 months of postgestational age, the greater trochanter ossifies at approximately 4 years of age, and the lesser trochanter ossifies at the age of 10 years.

The femoral shaft grows initially by enchondral ossification and production of a medullary cavity with calcification in the periphery and vascularization in the center, a process that results in a large primary ossification center. Woven bone results from this ossification and persists for the first 18 months of life, later becoming more adult-type lamellar bone. This longitudinal and peripheral growth continues until skeletal maturity.

The blood supply of the femoral shaft is from both endosteal and periosteal blood vessels. The endosteal supply is typically derived from two nutrient vessels that enter the femur from a posteromedial direction. The periosteal capillaries supply the outer 25% to 30% of cortical bone and are most prominent in the areas of muscular attachments to the femoral shaft ( Fig. 30.57 ). These two circulatory systems, together with the metaphyseal complex of vessels, are interconnected to provide a strong vascular supply that allows rapid fracture repair.

Mechanism of Injury

The mechanism of injury in femoral shaft fractures is largely correlated with age. Nonaccidental trauma, the leading cause of femoral fractures before walking age, accounts for 70% to 80% of fractures in this age group. ^, Between 1 and 4 years of age, 30% of femoral shaft fractures are attributed to abuse. A high suspicion of abuse must therefore be entertained, and an appropriate history and directed physical examination should be undertaken to look for other injuries. In addition to age, other factors that should raise the suspicion of child abuse include a first-born child, presence of a preexisting brain injury, bilateral fractures, subtrochanteric or distal metaphyseal beak fractures, and delay by the family in seeking treatment. Careful analysis is needed because returning a child to a home where abuse has occurred can result in more abuse (approximately 50%) and death in up to 10% of cases.

In the adolescent age group, high-velocity motor vehicle accidents are more often the mechanisms of injury and account for up to 90% of all femoral shaft fractures. ^, High-energy trauma results in more significant fracture displacement, which should alert the clinician to the high probability that life-threatening intraabdominal, intrathoracic injuries, and/or head injuries may be present. In a review of pediatric femoral fractures secondary to motor vehicle–related events, 14% were associated with head injuries. An organized, thorough initial examination and treatment are imperative in this setting and should reflect current treatment algorithms for a polytraumatized patient. ^,

The timing of fixation of femoral shaft fractures in pediatric patients was studied in a large series of polytraumatized patients. An unexpected decline in hemoglobin levels necessitates further trauma evaluation because this is often an indicator of concomitant injury. Unlike the case in adults, pulmonary complications rarely develop in children with multiple injuries and an associated femoral shaft fracture, and the timing of fracture stabilization does not appear to affect the prevalence of pneumonia or respiratory distress syndrome.

Minor trauma or repetitive fractures should alert the clinician to the possibility of an underlying pathologic condition, including osteogenesis imperfecta, the missed diagnosis of which is associated with significant stress and cost to the family. Generalized osteopenia from cerebral palsy, myelomeningocele, and other neuromuscular conditions also predisposes to fracture.

Radiographs should always be carefully evaluated for localized pathologic conditions that can predispose to fracture. The most common benign conditions include aneurysmal bone cyst, unicameral bone cyst, nonossifying fibroma, and eosinophilic granuloma ( Fig. 30.58 ). Malignant conditions are far less common and include osteogenic sarcoma, Ewing sarcoma, and rarely, metastatic disease. The femoral neck should be visualized on diagnostic radiographs as ipsilateral femoral neck and shaft fractures, though fairly rare, have been reported.

Another rare entity is a femoral shaft stress fracture, which is often accompanied by a longstanding complaint of pain in the thigh region in an adolescent athlete. No preceding trauma is recalled, and multiple medical opinions are usually sought without a conclusive diagnosis. Timely diagnosis and treatment are essential to prevent a subsequent complete fracture.

Classification

As with most diaphyseal fractures, classification of femoral shaft fractures is based on the radiographic examination and the condition of the soft tissue envelope (closed or open fracture). Radiographs are evaluated for fracture location (proximal, middle, or distal third), configuration (transverse, oblique, or spiral), angulation, the degree of comminution, and the amount of displacement, translation, and shortening. Winquist and colleagues classified the amount of comminution, which is especially useful when rigid intramedullary nailing is used to treat a femoral shaft fracture. Shortening is often measured in centimeters, the acceptability of which is age- and treatment-dependent with larger discrepancies (and expected resulting overgrowth) more acceptable in younger children. The physical examination determines whether an open injury is present, defined as a fracture that communicates with the external environment, usually because of penetration of the fracture fragment in an inside-to-outside fashion. The three-part Gustilo system is used to classify all open fractures and helps determine the specific treatment plan, including the antibiotic regimen.

Clinical Features

Examination of an injured child must be individualized according to the age of the child and the circumstances of the injury. Because many patients with femoral shaft fractures have sustained high-energy trauma, a multidisciplinary team approach is necessary (see Chapter 27 ). Careful and circumferential evaluation of the soft tissue envelope to look for areas of ecchymosis around the buttock and hip area may suggest an ipsilateral femoral neck or intertrochanteric fracture or hip dislocation. The skin should be thoroughly inspected to identify an open injury, which should be classified according to the Gustilo classification.

A neurologic and vascular examination of the involved extremity should be performed and the findings compared with those on the contralateral side. The findings on repeat neurovascular examination after gentle reduction and immobilization in a splint or in boot traction should remain normal.

Radiographic Findings

Standard AP and lateral radiographs of the entire femur, including the hip and knee joint, are necessary. In the proximal femur, femoral neck and intertrochanteric fractures and hip dislocations can be associated with a diaphyseal fracture and are missed in up to a third of cases. ^{, , ,} In the distal femur, associated physeal injuries and ligamentous and meniscal injuries can be seen. Poor-quality radiographs are unacceptable, and the study should be repeated before the patient leaves the emergency department or radiology suite if medical circumstances allow. In an older child, a Thomas traction splint that has been applied either in the field or on arrival in the emergency department often obscures the proximal femur on the initial radiographs ( Fig. 30.59 ). Hare traction splints meant to improve prehospital stabilization and transport should be removed on arrival at the tertiary treatment center to allow complete examination and imaging of the femur. These splints have been associated with complications including compartment syndromes, skin compromise, and ischemia.

The radiographs should be evaluated for fracture configuration, degree of comminution, displacement, angulation, and degree of shortening. This information is important in understanding the mechanism of injury and the force imparted to the bone and soft tissue, information ultimately used in planning treatment. The deforming forces of the surrounding musculature result in characteristic displacement patterns ( Fig. 30.60 ).

Plain radiographs are usually all that is needed to evaluate femoral shaft fractures. Rarely, stress fractures require CT or MRI to confirm the diagnosis. CT is best used to evaluate intraarticular fractures of the femoral head and distal femur, hip dislocations (to assess for intraarticular loose fragments after reduction), and physeal injuries. Angiography is indicated in the setting of diminished or absent pulses associated with a femoral shaft fracture, knee dislocations, ^, and often in the presence of an ipsilateral tibial fracture (floating knee).

Treatment

The age of the patient, the size of the child, and the fracture location are the most important factors in deciding which treatment modality is most appropriate.

In general, we prefer to treat a younger child nonoperatively in a Pavlik harness or hip spica cast and an older child with some form of internal skeletal fixation. Additional factors to consider include the mechanism of injury, the presence of multiple injuries, the soft tissue condition, the family support environment, and the economic resources available. Finally, as in any form of orthopaedic treatment, the experience, skill, and preference of the treating physician play significant roles in determining treatment. We use the following guidelines, based on the age of the patient, to determine treatment.

Age Guidelines

0 to 6 Months

In a child 6 months or younger immediate application of a Pavlik harness results in an excellent outcome, with time to union averaging 5 weeks. ^, Advantages of the Pavlik harness include ease of application without requiring a general anesthetic or sedation, minimal hospitalization, ability to adjust the harness when fracture manipulation is required, ease of nursing and diapering, and absence of the skin irritation commonly associated with casting. Excessive hip flexion in the presence of a swollen thigh may compress the femoral nerve, and the surgeon should monitor quadriceps function during treatment to detect such an injury ( Fig. 30.61 ). Pavlik harness immobilization rarely provides anatomic reductions and therefore rely on the significant remodeling potential of the infantile femur. In certain situations, even in younger children, the use of spica cast immobilization may be considered. We typically reserve this use to patients or family members who do not or cannot tolerate Pavlik harness treatment.

7 Months to 5 Years

When shortening of the fracture is limited to less than 2 to 3 cm and the fracture has a stable, simple pattern, we prefer to treat the child by closed reduction and immediate spica cast application ( Fig. 30.62 ). Skin or skeletal traction may be required when excess shortening (>3 cm) or angulation (>30 degrees) is present. In a multiply injured patient, traction may be used until associated injuries permit definitive treatment, without negatively affecting outcomes. ^, Definitive treatments may be casting, flexible intramedullary rods, internal fixation, or external fixation, depending on associated injuries. While spica casting remains the standard in this age group producing excellent results, surgical stabilization with intramedullary fixation is also proven to be safe and effective in younger patients and may be used to improve mobilization or in the face of polytrauma. ^{, , , ,}

6 to 10 Years

Femoral shaft fractures in children between 6 and 10 years of age are routinely treated by closed or open reduction and stabilized with flexible rods (Enders stainless steel or Nancy titanium elastic nails), especially when a stable transverse fracture pattern is present. Our general guideline for the management with flexible nails includes a weight of less than 100 lb. Certain injury patterns and patients allow this guideline to be altered, and we have found that this published weight limit can be raised with use of stainless steel Ender’s nails. Additional modes of treatment include skeletal traction followed by spica cast treatment (which is rare in the US today), compression plate fixation, submuscular bridge plating, or external fixation ( Fig. 30.63 ). Specific treatments are discussed below.

11 Years to Skeletal Maturity

Flexible intramedullary rodding is an acceptable choice with a stable fracture pattern. Submuscular plate fixation may be considered for unstable patterns. With newer and better smaller-diameter trochanteric entry nails available, many children with length-stable or unstable injuries can be treated with locked intramedullary fixation. Advantages of solid nailing include earlier weight bearing, and improved stability of fixation in larger children who could otherwise have a compromised result with flexible nails.

Treatment Techniques

Traction

We rarely use traction for definitive treatment; we prefer techniques that allow for mobilization and ease of care. However, most patients are put into soft, skin traction on arrival in the emergency department, allowing for more comfortable rest until surgery or casting can be accomplished

Skin Traction

Skin traction is a noninvasive technique that is used in two settings. First, in a small child whose fracture is too shortened (>3 cm) to allow immediate spica casting, traction is used to align the fracture until enough callus formation has occurred to permit spica cast application. Second, in any child who is to undergo definitive skeletal fixation on a delayed basis, skin traction temporarily stabilizes and aligns the leg and thereby provides some stability and comfort in the interim period ( Fig. 30.64A ).

Although skin traction is effective in these settings, it has potential problems and complications. Used in a very young child (<2 years), Bryant traction (see Fig. 30.64A and B ) consists of overhead skin traction with the hips flexed to 90 degrees and the knees fully extended. When more weight is required to control the fracture, we prefer to use skeletal traction.

Skeletal Traction

Skeletal traction is a more powerful technique to apply traction to the femur, although its use is limited to rare instances in the United States now as an alternative treatment strategy. It is used in therapies such as early intramedullary nailing of polytrauma patients, when stability is needed. It is used in an older child with a diaphyseal fracture, when more than 5 to 10 lb of weight is required, and in any child with a proximal femoral fracture in whom 90–90 traction is needed. The distal end of the femur is the best site for placement of the traction pin, which should be inserted parallel to the knee joint to prevent varus or valgus deformity ( Fig. 30.65 ). Using sedation and under sterile conditions, the distal femoral traction pin should be inserted just superior to the adductor tubercle and advanced laterally ( Fig. 30.66 ). When soft tissue injury and contamination prevent femoral traction pin placement, the traction pin can be inserted in the proximal end of the tibia, but only after the knee has been carefully examined to exclude ligamentous injuries. The proximal tibial traction pin should be placed distal to the tibial tubercle physis to avoid anterior growth arrest and the development of a recurvatum deformity. ^{, ,}

Results and Cautions

Traction should reduce the fracture to within 2 cm in a younger child, and end-to-end apposition should be achieved in a child older than 11 years. Radiographs of the femur should be obtained in both the AP and lateral views to check alignment and callus formation. Traction can be continued for 2 to 3 weeks, until callus forms and the child has minimal or no tenderness on palpation at the fracture site. In the past, traction pins were incorporated into a hip spica cast at an early period to better control the fracture; however, this is frequently complicated by pin tract infection and pin breakage.

Spica Casting

Immediate spica casting has been advocated in a child with an isolated stable femoral shaft fracture and less than 3 cm of shortening, in a child younger than 8 years, and for a fracture without massive swelling of the thigh. ^{, ,} A period of traction can be used if concerns about safety or reduction arise. Another important factor is the social situation in which the child is living, because the most difficult problems encountered by families have to do with transporting the child and keeping the child clean in the cast. Skin complications are well described in the spica-casted population, and are the most common reason for repeat anesthetic. Preschool children tolerate a spica cast much better than do school-aged children because younger children can be transported more easily and have shorter healing times. The use of single-leg spica casting has been demonstrated to be safe and effective and may ease the burden of treatment on the family. ^, In certain settings, application of the cast in the emergency department rather than the OR can lead to equivalent outcomes at reduced medical cost.

Traditional spica casting puts the hips flexed approximately 60 to 90 degrees (the more proximal the fracture, the more the hip should be flexed), 30 degrees of hip abduction, and 90 degrees of knee flexion ( Fig. 30.67 ). Some external rotation corrects the rotational deformity of the distal fragment. Several authors previously recommended placing a long-leg cast initially and then transferring the patient to the hip spica table and applying the remainder of the cast. ^, We and others recommend placing the patient on the spica table and applying the entire cast from proximal to distal while an assistant holds the fracture in a reduced position. Compartment syndrome of the lower part of the leg is a recognized complication of early spica casting and may be more common when excessive traction is applied or when a short-leg or long-leg cast is first applied and pulled to improve reduction. ^,

Radiographs in the lateral and AP planes are obtained before the cast hardens to allow mild angular manipulation. Acceptable alignment depends on the age of the patient but, in general, is considered to be no more than 15 degrees of deformity in the coronal plane and 25 to 30 degrees in the sagittal plane. ^, Shortening should not exceed 3.0 cm. Radiographs should be obtained regularly during the first 2 to 3 weeks to allow correction of any loss of the initial reduction. Excessive shortening within this period can be corrected by removal of the cast and a short time in traction followed by recasting. Wedging of the cast allows some correction of angular deformity (up to 15 degrees) but must be done with caution because peroneal palsy has been reported during correction of valgus deformities ( Fig. 30.68 ). Femoral fractures that are more susceptible to losing reduction are fractures resulting from a high-energy mechanism, fractures in older children, and fractures associated with polytrauma.

External Fixation

The main indications today for external fixation are as follows: (1) an open fracture with severe disruption of the soft tissue envelope, including severe burns; (2) multiple trauma and a patient in extremis requiring expedited long bone stabilization; (3) an extremity with an arterial injury requiring immediate revascularization of the extremity; (4) some unstable fracture patterns; and (5) failed nonsurgical management. ^k

k References , , , , , , .

Many institutions use external fixation as a temporary option until the soft tissues or medical emergencies are improved and conversion to internal fixation can be performed.

Unilateral fixators are relatively easy to apply and allow angular correction during the follow-up period ( Fig. 30.69 ). When used definitively, the fixators are generally left on for 10 to 16 weeks until solid union has been achieved. Weight bearing is permitted as early as tolerated and depends to some degree on the stability of the fracture and the external fixator.

The most common complication of treatment with an external fixator is pin tract infection (approximately 50% of cases), which generally responds to pin care and antibiotics. Rates of nonunion, delayed union, and angular deformity are generally reported to be slightly higher than when more rigid fixation techniques are used. Re-fracture is also more common, with a reported incidence of 1.5% to 21% ( Fig. 30.70 ). ^l

l References , , , , , , , .

These complications are most common in fractures with a short oblique fracture pattern. Shortening and overgrowth have not been major issues; less than 5 mm of overgrowth is commonly reported, and complete apposition of the fracture fragments should be achieved at the time of initial reduction. ^,

Open Reduction and Internal Fixation

Proponents of internal fixation with plates and screws recommend this form of treatment for children with multiple trauma or patients with closed head injuries. The main advantages of this technique are that fracture stabilization is performed quickly, anatomic reduction is achieved, and the fracture is rigidly fixed, thereby allowing early mobilization. Open reduction with plate fixation is relatively easy to perform, and this method can be used in any age group ( Fig. 30.71 ). The disadvantages are the large incision and soft tissue stripping, the risk of plate breakage and re-fracture, and the potential need for plate removal, with a risk for recurrent fracture. Because anatomic reduction with end-to-end bony apposition is achieved, overgrowth can be seen, although it has not been reported to be a clinical problem.

Submuscular Bridge Plating

Submuscular plating through a limited approach with indirect fracture reduction has been shown to be a useful technique for comminuted fractures and other patterns with significant potential for fracture shortening. ^m

m References , , , , , .

In this technique, the plate is inserted submuscularly and superficial to the periosteum through an incision over the proximal or distal metaphyseal flare. The fracture is reduced with manual traction or the assistance of a fracture table, and the plate is used to bridge the unstable portion of the fracture. Radiographic anatomic reduction is not required with a bridge plate. Fluoroscopic assistance is used to reduce the fracture and place screws in a percutaneous fashion through closely spaced incisions. Initial plate placement may be maintained by the use of Kirschner wires in the proximal and distal holes, and screws may be used to achieve reduction of the femur to the plate.

The plate is routinely removed 6 to 9 months after insertion. Several series demonstrated minimal complications with an average time to union of 12 weeks. ^{, ,} The ability to maintain length reduction through a limited approach makes this technique a viable alternative to flexible intramedullary fixation for fracture patterns with the potential for length instability ( Fig. 30.72 ). Submuscular plating has become more popular recently with improvements in instrumentation systems, however, the treating surgeon should be aware of reports of valgus overgrowth at the knee when the plate is close to the distal femoral physis as well as challenges with plate removal including postoperative fracture and increased intervention for removal than insertion when bony overgrowth occurs. ^,

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