Pediatric Musculoskeletal Disorders

Anatomy and Physiology

Due to the dynamic developmental state occurring in growing children, the pediatric skeleton is unique compared to adults. The most unique feature of pediatric bones is the presence of the physis. This growth plate is composed of proliferating cartilage cells between the epiphysis and metaphysis. The physis is the weakest part of the bone and allows for distinctly different fracture patterns and injury mechanisms compared to adults. The physis can separate or fracture before the adjacent ligaments and tendons tear; similar injury mechanisms in adults which result in sprained ligaments can cause physeal injuries in children. These injuries are most common during periods of rapid growth and represent up to 18% of pediatric fractures.

The pediatric periosteum is thicker and stronger than mature periosteum, which can result in a reduction of fracture displacement. It is also physiologically active which allows for rapid healing and increased stability, making nonunion unlikely. Children have tremendous remodeling potential which allows for greater degrees of angulation or misalignment. If the child has at least 2 years of growth potential remaining, a fracture adjacent to a joint will remodel acceptably if the angulation is less than 30 degrees in the plane of motion.

Fracture Patterns

Immature bones are more porous and pliable, resulting in fracture patterns seen uniquely in pediatric injuries:

• Plastic deformity results in bowing of the bone without cortical disruption.

• Torus (buckle) fractures tend to occur from linear compression and result in buckling of bone without cortical disruption. These injuries are common at the metaphyseal-diaphyseal junction ( Fig. 170.1 ).

  

• Greenstick fractures disrupt the cortex unilaterally, with periosteum on the compression side remaining intact ( Fig. 170.2 ). The degree of acceptable angulation without reduction is age dependent. Children under 5 years of age can have up to 35 degrees of angulation on lateral radiograph and less than 10 degrees of angulation on AP views, whereas children 5 to 10 years old can tolerate up to 25 degrees on lateral and less than 10 degrees on AP view without need for reduction. Children older than 10 years of age can tolerate 5 to 20 degrees of angulation on lateral x-ray, presuming no angulation on AP view. Treatment for greenstick fractures generally involves casting for 4 to 6 weeks.

  

• Complete fractures transect both cortices of the bone; these include transverse ( Fig. 170.3 ), spiral ( Fig. 170.4 ), oblique, and comminuted ( Fig. 170.5 ).

  
  
  

• Physeal fractures are not specific to pediatrics but are more likely during periods of rapid bone growth. The Salter-Harris classification is commonly used to delineate fracture patterns as they relate to the physis ( Table 170.1 ). Concern for physeal injury stems from the potential for growth arrest and limb-length abnormalities. Nondisplaced Salter-Harris type I and II fractures ( Fig. 170.6 and Fig 170.7 ) are generally low risk for these complications because the germinal layer of the physis is not commonly involved. These fractures can be splinted or casted with orthopedic follow-up within 1 week. Salter-Harris type III, IV, and V fractures ( Fig. 170.8 through 170.10 ) are at greater risk for damage to the growth plate and are commonly unstable, requiring prompt orthopedic consultation. Types III and IV involve the joint surface and commonly require open reduction to maintain joint stability. Type V fractures are followed closely, as the risk for premature growth plate closure is high and surgical intervention is often needed.

  TABLE 170.1

  Salter-Harris Fracture Classification

  Type	Description
  I	Fracture extends through the physis
  II	Fracture extends from the physis into the metaphysis (away from the joint space)
  III	Fracture extends from the physis into the epiphysis (toward the joint space)
  IV	Fracture extends from the physis into the metaphysis and epiphysis
  V	Crush injury of the physis

  
  
  
  
  

Clavicle Fracture

Clavicle fractures are common in childhood but generally heal without complication. Most fractures occur between the middle and distal third of the bone. Mechanisms include birth trauma, direct trauma to the bone itself, and falls onto the shoulder. The bone’s superficial lie allows for easy palpation when evaluating for pain or deformity. A clavicle fracture may be detected later in a neonate when a visible callus has formed around day 10 or per parent history of crying when being picked up.

The patient with a clavicle fracture commonly complains of pain at the clavicle and shoulder, often with neck and arm movement. An anteroposterior radiograph of the clavicle is sufficient for diagnosis ( Fig. 170.11 ). Displacement of the affected shoulder along with crepitus and edema may be present upon inspection. The proximity of the clavicle to the subclavian vessels as well as the brachial plexus warrants a thorough neurovascular examination, especially in the setting of a displaced fracture. Complications can be seen in the setting of proximal fractures or posterior sternoclavicular displacement which can injure the trachea, esophagus, or cause pneumothorax.

Most children and adolescents with clavicle fractures only require supportive care and immobilization involving sling and swath for 4 to 6 weeks. However, recent studies suggest adolescents after 12 years of age have limited clavicular growth potential remaining and some surgeons have begun to use operative indications for adult patients in their pediatric population. Figure-of-eight splinting is not recommended due to risk of brachial plexus palsy with prolonged use. Newborns generally require no treatment following clavicle fractures from birth. Orthopedic consult should be obtained for clavicular fractures that are open, associated with neurovascular compromise, evidence of a floating shoulder (when associated with a scapular fracture), or with significant skin tenting. An orthopedic referral should be considered in fractures that are comminuted, have a substantial degree of displacement, or in high-level athletes as surgery may facilitate a faster return to activity.

Supracondylar Fractures of the Humerus

Supracondylar humerus fractures are the most common fractures involving the elbow in pediatric patients. During childhood, the tensile strength of the ligaments surrounding the joint exceed that of the weaker bones themselves, which increases the likelihood for fractures rather than ligamentous injury. Typically the patient history involves a fall onto an extended arm, forcing the distal bone superiorly and posteriorly.

Radiographic evaluation of elbow injuries include an AP view of extended elbow (if possible), oblique view, and lateral flexed view. The elbow joint contains 6 cartilaginous ossification centers which can be easily mistake for fracture lines ( Fig. 170.12 ). An acronym for remembering the order of appearance of the ossification centers is CRITOE ( Table 170.2 ).

Injury mechanisms involving impact on flexed elbow result in anterior displacement of the distal fragment. Supracondylar fractures are classified as either flexion or extension injuries, of which the latter is more common. An AP and lateral radiograph are required to evaluate the degree of displacement and continuity of the cortex as defined by the Gartland classification ( Table 170.3 ). Because subtle fractures can be difficult to visualize, the anterior humeral line can be used as indirect evidence of fracture ( Fig. 170.13 ). A true lateral view should demonstrate a figure-of-eight appearance of the distal humerus, with intersection of the anterior humeral line with the posterior two-thirds of the capitellum. If this line intersects the anterior one-third of the anterior capitellum or is anterior to this structure, then a supracondylar fracture with posterior displacement of the distal fragment is suggestive. The Baumann angle, normally 70 to 75 degrees, can be helpful in detecting subtle fractures and is formed by a line drawn to follow the growth plate of the capitellum intersected with a line drawn down the center of the humerus ( Fig. 170.14 ).

Fat pads are markers for joint effusions or hemorrhage and raise suspicion for occult fracture. On a lateral radiograph with the elbow flexed at 90 degrees, the anterior fat pad demonstrates radiolucency anterior to the coronoid fossa. When thin, this can be a normal finding in children, but is considered a “sail” sign of occult fracture when bulging. The posterior fat pad is posterior to the distal humerus and always represents a pathologic effusion ( Fig. 170.15 ).

The injured patient presents with a painful swollen elbow and typically holds the extremity in extension and slight pronation. Puckering, dimpling, or anterior bruising are indications that reduction may be difficult, as the anteriorly displaced fragment may have penetrated the brachialis muscle. Immediate assessment should include evaluating for neurovascular compromise by assessing capillary refill and palpating both radial and ulnar pulses. Signs of arterial compromise include the 5 “Ps”: pain, pallor, pulselessness, paralysis, and paresthesias. Worsening pain or pain with passive extension of the fingers is a concerning sign of limb ischemia and can lead to Volkmann ischemic contractures. Emergent consultation with an orthopedic surgeon should be initiated and fracture reduced expeditiously in an attempt to restore blood flow ( Fig. 170.16 ). Perfusion should be confirmed via radial artery signal by Doppler following closed reduction attempts; if reperfusion is unsuccessful, emergent vascular exploration is warranted to assess for and repair brachial artery injuries.

Because major nerves and arteries lie in proximity to the supracondylar region, a full motor and sensory function should evaluate for possible associated injury or entrapment. Major structures include radial, ulnar, and median nerves ( Table 170.4 ). The median and radial nerves are commonly injured in extension injuries when the distal fragments are displaced posterior-laterally and posterior-medially, whereas the ulnar nerve is commonly affected with flexion injuries.

Supracondylar humerus fractures are the most common fractures treated surgically by pediatric orthopedic surgeons. Management of Gartland type I fractures can be placed in a posterior long arm splint with the elbow flexed at 90 degrees and either neutral or pronated position. These patients should follow up with an orthopedist with 24 hours for evaluation and casting. Gartland type II and III fractures require emergent evaluation by an orthopedic surgeon. Type II fractures require closed reduction, but if greater than 90 degrees of flexion is required to maintain reduction, then stabilization with percutaneous pinning is advised. Treatment of type III supracondylar fractures includes admission and should include operative reduction and pinning, because they are prone to neurovascular compromise.

Monteggia and Galeazzi Fracture-Dislocations

Monteggia fracture-dislocation represents a fracture of the proximal third of the ulna plus dislocation of the radial head ( Fig. 170.17 ). Isolated ulna fractures are uncommon in children and can present as a plastic deformity of the ulna without obvious fracture. The radiocapitellar line, drawn down the radial shaft, should pass through the center of the capitellar ossification center on lateral elbow radiograph; radial head dislocations will disrupt this line ( Fig. 170.18 ). In contrast, the Galeazzi fracture is characterized as a fracture of the distal radius and disruption of the distal radioulnar joint.

For both fracture types, orthopedic consultation is needed for closed reduction and casting. Management of the Monteggia fracture is predicated on recognizing the radial head dislocation, and reduction and stabilization of the ulnar fracture generally results in radial head reduction. Failure to reduce the radial head over time can result in valgus instability of the elbow, arthritis of the elbow, and restricted forearm pronation.

Nursemaid’s Elbow

Nursemaid’s elbow (i.e., radial head subluxation) occurs when the head of the radius is displaced from the annular ligament; it represents approximately 20% of pediatric upper extremity injuries, with a peak incidence between two and three years of age. The typical mechanism occurs when axial traction is placed on the forearm, causing extension of the elbow and pronation. This movement permits subluxation of the radial head via partial tearing or entrapping of the annular ligament between the radial head and capitellum ( Fig. 170.19 ).

Patients generally present with unwillingness to use the affected arm, which is typically held against the body, slightly flexed at the elbow with the arm pronated. Edema, ecchymosis, or deformity are typically absent. Gentle palpation usually does not illicit pain of the long bones or elbow joint, although ranging the extremity can cause distress. The diagnosis of nursemaid’s elbow is made clinically; AP and lateral radiographs of the elbow should be obtained if there is focal bony tenderness, ecchymosis, joint swelling, or a traumatic mechanism.

Two common techniques for reduction are supination/flexion and hyperpronation maneuvers. Both methods involve the examiner supporting the child’s arm at the elbow by placing pressure with a finger on the radial head. In the supination/flexion maneuver, the examiner holds the forearm with their other hand and provides gentle traction while fully supinating and flexing the elbow in one motion. With hyperpronation, the examiner holds the affected arm’s hand in a handshake grip and grips the elbow with the other hand. Hyperpronation of the forearm usually results in a palpable click over the radial head if reduction is successful. Both methods are effective, however, meta-analysis of randomized control trials have shown that hyperpronation is more effective, with a lower first attempt failure rate. Recurrence is common and parents should be cautioned to avoid lifting the child by the arm or wrist, but may be taught to perform the maneuver themselves if it recurs.

Children typically begin using the arm normally within 15 minutes. If the child fails to move the extremity, repeat maneuvers may be attempted. However, if unsuccessful, radiographs should be obtained and the extremity placed in a long arm splint at 90 degrees. Pediatrician follow-up should be arranged within next 24 hours.

Toddler’s Fracture

The toddler’s fracture is a nondisplaced oblique fracture of the distal tibia that is the result of a minor fall or twisting mechanism, with a peak incidence between 1 and 4 years of age. Clinical diagnosis may be difficult, as the history may be vague and the physical examination is commonly nonspecific to a local injury. Typically, guardians report the child is limping or unwilling to bear weight; there may be a report of a minor fall. Tenderness may be elicited with palpation, but obvious swelling or deformity is uncommon. Gentle twisting of the lower leg may provoke pain.

Lower leg AP and lateral radiographs may reveal a subtle oblique lucency through the distal tibia terminating medially ( Fig. 170.20 ). Because children have robust periosteum, any displacement can be minimal, making identification on radiograph difficult, and the fracture is often not initially visible. If suspicion for a toddler fracture is high, immobilization and reevaluation 2 weeks later will show callus formation on repeat radiographs from new periosteal growth. If available, ultrasound can be considered as an imaging modality to evaluate for fracture. Traditionally, immobilization involved a posterior long leg cast for 3 to 4 weeks, but recent studies have shown no differences in the clinical outcomes between various immobilization methods: casting, splinting, or a cast boot. Casts should not extend above the knee on young toddlers, who are at risk for cast migration. Children are allowed to bear weight as tolerated after immobilization.

Nonaccidental Trauma

The National Child Abuse and Neglect Data System reported more than 680,000 children were victims of maltreatment and 1670 children died of abuse and neglect in 2015. Of all these childhood fatalities 43.9% were victims of physical abuse exclusively or in combination with another maltreatment type and 74.8% of these children were less than 3 years of age. Diagnosis of physical abuse can be elusive and missed identification can lead to additional injuries. An estimated 25% of children diagnosed with nonaccidental trauma (NAT) have a sentinel injury before their abuse diagnosis. These data underscore the necessity for a thorough evaluation when there is a concerning history or physical findings for NAT. See Chapter 172 for a complete discussion on the evaluation of NAT.

Developmental Dysplasia of the Hip