General Principles of Orthopedic Injuries

Anatomic Location of a Fracture: Nomenclature

Describing orthopedic injuries with precise language according to established convention enables accurate and clear communication with other providers and consultants. Terms commonly used to describe a fracture are listed in Box 41.1 . A fracture is a break in the continuity of bone, which may be more subtle in children. Clinically, a history of trauma, loss of function, pain, tenderness, swelling, abnormal motion, and deformity all suggest a fracture.

Anatomic Descriptors

Description of a fracture should begin by stating whether the fracture is closed or open. In a closed fracture, the skin and soft tissue overlying the fracture site are intact. The fracture is considered open if it is, or has been, exposed to the outside environment in any manner, which may not be immediately obvious. Occasionally, it is difficult to determine whether a small wound in proximity to a fracture communicates with that fracture. Probing such a wound with a blunt sterile swab to establish a relationship may not be safe or accurate and should be avoided. If doubt exists, an open fracture should be assumed to be present and treated as such.

The exact anatomic location, including the name of the bone, left or right, and standard reference points along the bone (e.g., the humeral neck or posterior tibial tubercle) should be noted. Long bones can be divided into thirds—proximal, middle, or distal—and these thirds, or the junction of any two of them (e.g., the junction of the middle and distal thirds of the tibia), are often used to describe fractures. The most descriptive language possible should be used. It is better to say “closed fracture of the right ulnar styloid” than “closed fracture of the right distal ulna” because the former conveys more precise anatomic information and will help guide optimal treatment.

An additional modifier describes the direction of the fracture line in relation to the long axis of the bone in question. A transverse fracture occurs at a right angle to the long axis of the bone ( Fig. 41.1A ) whereas an oblique fracture runs oblique to the long axis of the bone (see Fig. 41.1B ). A spiral fracture results from a rotational force, a torque, and encircles the shaft of a long bone in a spiral fashion (see Fig. 41C ). The terms oblique and spiral are sometimes confused but can be important since the latter may have significance when child abuse is being considered as a mechanism of injury. A fracture with more than two fragments is termed comminuted (see Fig. 41.1D ).

The position and alignment of the fracture fragments (i.e., their relationship to one another) should be described. Fragments are described relative to their normal position, and any deviation from normal is termed displacement. By convention, the position of the distal fragment is described relative to the proximal portion. Displacement may be described as a quantitative measurement (i.e., in millimeters) or as an approximate percentage of the bone width. It also may be described qualitatively as non, minimal, moderate, or severe. Fig. 41.2 shows dorsal displacement of the fractured radius, and Fig. 41.3 shows lateral, or valgus , displacement of the distal tibia and fibula.

A lignment refers to the relationship of the longitudinal axis of one fragment to another; deviation from the normal alignment is termed angulation. The direction of angulation is determined by the direction of the apex of an angle formed by the two fracture fragments ( Fig 41.4 ). The term valgus denotes a deformity in which the apex of the deformity points toward the midline. Conversely, the term varus denotes a deformity in which the apex of the angulation points away from the midline. The relative position or angulation of the distal fragment of a fracture may also be described with terms such as radial or ulnar, dorsal or volar, anterior or posterior, and lateral or medial. For the forearms and hands, the anatomical position (palms up) should be used, along with radial and ulnar rather than medial and lateral to describe the direction of displacement. One should also be aware of rotational deformity, present when the distal fragment of a fracture is rotated to some degree along the axis of the bone itself. Especially in the digits of the hand, when the finger is flexed, clinically significant radial or ulnar deviation may be present that are not seen on radiographs (see Chapter 42 ).

Descriptive Modifiers

A fracture is termed complete if it interrupts both cortices of the bone on orthogonal radiographic views and termed incomplete if one cortex remains intact. It should be noted whether a fracture extends into and involves an articular surface. Frequently, the percentage of articular surface involved can only be estimated; in some cases, the estimated percentage that is involved dictates the need to perform a surgical intervention. In general, it is important that the articular surface be restored to anatomic integrity to prevent consequent posttraumatic arthritis or disability.

The term avulsion fracture refers to a bone fragment that is pulled away from its normal position by the forceful contraction of a muscle ( Fig. 41.5A ) or the resistance of a tendon or ligament to a force in the opposite direction (see Fig. 41.5B ). The term impaction refers to the forceful collapse of one fragment of bone into or onto another. In the proximal humerus, this collapse typically occurs in a telescoping manner, particularly in older patients, whose bones are osteoporotic and brittle. In the tibial plateau, impaction occurs frequently in the form of a depression ( Fig. 41.6A and B ) and, in the vertebral bodies, impaction frequently occurs in the form of compression resulting in a significant loss of bone height in some cases (see Fig. 41.6C ).

A fracture that occurs through abnormal or diseased bone is termed pathologic. A pathologic fracture is suggested whenever a fracture occurs from seemingly trivial trauma. Diseases that cause structural weakness predisposing to injury include primary malignancy or malignant metastatic lesions, bone cysts, enchondromas, and giant cell tumors. In addition, metabolic and genetic disorders such as osteomalacia, scurvy, rickets, vitamin D deficiency, Paget disease, and osteogenesis imperfecta can alter bone density, making them susceptible to fracture. The term pathologic is also often applied to fractures through osteopenic bone when demineralization is a result of disuse, as in polio. In contrast, fractures through osteoporotic bone of older adults usually are not described as pathologic; these are more accurately referred to as geriatric or insufficiency fractures. When fractures occur in normal bones and a history of supposed trivial trauma or a suspicious mechanism is elicited, interpersonal violence or abuse should be suspected, and safety of the patient assured.

Repeated low-intensity forces may lead to resorption of normal bone, resulting in a stress fracture. Other terms for this condition are fatigue fracture and march fracture (see Table 41.1 ). Most stress fractures occur in the lower extremities and affect individuals involved in activities such as long-distance running, basketball, aerobics, and dancing. There is often a history of functional pain leading up to the fracture. Extrinsic factors such as training regimens, type of equipment used, nutrition habits, as well as intrinsic factors such as anatomic variation, muscle endurance, and hormonal factors, have all been associated with stress fractures. The tibia, fibula, metatarsals, navicular, cuneiform, calcaneus, femoral neck, or femoral shaft may be involved. These injuries may not be recognizable on initial plain films. Management therefore should be based on the clinical diagnosis.

Fracture Eponyms and Mechanistic Names

Many fractures were described before the advent of radiography and are described shorthand by an eponym or other name rather than by the exact bony injury. These eponyms and mechanistic names reflect the storied history of medicine and orthopedic care and are still commonly used to describe specific orthopedic injuries (see Table 41.1 ).

Epiphyseal Fractures

Fractures involving the epiphyses in children and adolescents are described according to the Salter-Harris classification ( Table 41.2 ). The clinical features of fractures in children are further discussed in Chapter 170 .

TABLE 41.2

Salter-Harris Classification

Type	Description	Diagram
I	Fracture extends through the epiphyseal plate, resulting in displacement of the epiphysis; this may appear merely as widening of the radiolucent area representing the growth plate.
II	As above; in addition, a triangular segment of metaphysis is fractured.
III	Fracture line runs from the joint surface through epiphyseal plate and epiphysis.
IV	Fracture line occurs as in type III but also passes through adjacent metaphysis.
V	This is a crush injury of the epiphysis; it may be difficult to determine by radiographic examination.

Fracture Healing

The goal of fracture reduction is to realign major bony fragments so that union can take place, and normal function is restored. In the initial stage of healing, a hematoma caused by the rupture of a vessel crossing the fracture line forms a hematoma. This hematoma eventually resorbs and provides the first continuity between the fragments. This procallus provides no structural rigidity for bearing stress but, with calcification and remodeling, callus is formed on the periosteal and endosteal surfaces of the bone, acting as a biologic splint. Over several months to a year, the callus normally completely ossifies, remodels, and becomes indistinguishable from mature bone.

Radiographic studies conducted 10 to 14 days after injury further reveal the fracture line as it becomes more visible due to localized bone resorption and hyperemia during the inflammatory phase. After 2 to 4 weeks, soft tissue swelling has regressed, and callus first becomes visible, initially in a mottled pattern and then taking on a dense appearance. Callus then undergoes organization, with peripheral margins becoming smooth as physically unstressed portions are resorbed.

In a healthy adult, the entire process from injury to consolidation takes approximately 2 months for the humerus and about 4 months for a large bone such as the femur. The rate of fracture healing is affected by the type of bone (cancellous bone heals faster than cortical bone), degree of fracture and opposition, systemic states, such as hyperthyroidism, use of corticosteroids, smoking, or illness requiring immobilization. Oblique fractures tend to heal more quickly than transverse fractures because of the greater amount of surface contact and a buttressing effect. Appropriately timed weightbearing can increase the rate of ossification of callus, whereas premature or excessive weightbearing can create a nonunion.

The presence of abundant bridging callus that is beginning to organize radiographically is usually associated with clinical union. If there is any suggestion of movement at the fracture site noted on clinical examination, union is regarded as inadequate. Several terms are used to denote abnormal healing. Delayed union is union that takes longer than usual for a particular fracture location; malunion occurs when a residual deformity exists; and nonunion is the failure of a fracture to unite. When nonunion results in a false joint, it is termed a pseudarthrosis.

If there is clinical evidence of stability, such as pain-free weightbearing, and radiographs demonstrate bridging bone at the cortices, a patient may resume activities of daily living with the injured extremity, even if the original fracture remains visible. The process of complete radiographic consolidation or healing can take several additional months.

Infection (Osteomyelitis)

A fracture that communicates with the surface of the skin is termed an open fracture. Open fractures are treated as true, time-dependent orthopedic emergencies because of the risk of bone infection, or osteomyelitis . The high morbidity associated with osteomyelitis dictates that therapy be initiated expeditiously, including parenteral administration of antibiotics as early as possible, coverage with a moist dressing, and emergent washout of debris. The Gustilo-Anderson classification is commonly used to describe the various types of open fractures ( Box 41.2 ).

Suggested antibiotic therapy currently includes a first-generation cephalosporin, such as cefazolin, 2 g IV every 8 hours, for all open fractures, with the addition of an aminoglycoside, such as gentamicin, 5 mg/kg once daily, for type II or III fractures. Alternatively, a beta-lactam with both gram positive and negative coverage (e.g., ceftriaxone or piperacillin-tazobactam) may provide equivalent benefit. For patients with farm-related injuries or those with potential fecal contamination, ampicillin or penicillin should be added to the treatment regimen to empirically cover for clostridial contamination. Early versus delayed debridement of open fractures and the subsequent effect on rates of infection has been a source of debate. Historic guidelines recommending debridement of open fracture wounds within 6 hours of injury were based on animal experiments conducted in the 1890s. The timing of debridement—less than 6 hours versus more than 6 hours after injury—has not been proven to change outcome, but general practice is to undertake debridement and irrigation of the wound within the first 24 hours of injury. Regardless, the goals of open fracture management in the ED should focus on early administration of antibiotics, tetanus prophylaxis, dressing coverage of the wound, and splinting of the extremity.

Open distal tuft fractures of the fingers and toes are a notable exception to the previous recommendation. These are common when the phalanx of a finger or toe is subject to crush injury (e.g., by a closing door) and there is a skin wound overlying a fractured bone. Treatment of these injuries can be provided by the emergency clinician without the need for immediate consultation. Vigorous irrigation and debridement are adequate primary treatment for these injuries, provided digital arteries are intact. Infections of the tuft region are rare.

Hemorrhage

Because of the rich blood supply to the skeleton, fractures can result in large amounts of blood loss, shock, and even death from exsanguination. In particular, certain pelvic fractures can cause major blood loss because adequate tamponade is not possible. In adults, blood loss can range from 100 mL from a forearm fracture to 3 L from a pelvic fracture ( Table 41.3 ). Such hemorrhage can be controlled in part by early stabilization of the injured area through splinting, a binder, or skeletal traction. Definitive treatment options include embolization by an interventional radiologist or by emergent surgical intervention (see Chapter 46 ).

Vascular Injuries

Vascular injuries are characteristically associated with certain fractures and may be limb threatening. Fractures and dislocations at the femorotibial articulation of the knee result from tremendous force, which may injure the popliteal artery and lead to the need for amputation (see Chapter 48 ). Fracture of the femoral neck requires emergent fixation regardless of the need for reduction to protect the blood supply to the femoral head and prevent aseptic necrosis. In the extremities, assessment of vascular injuries may be challenging. The initial survey should note the presence or absence of pulses and the state of capillary filling. If an end artery is completely disrupted, the tissue distal to the injury may exhibit the classic five Ps: pain and paresthesias (in the conscious patient), followed by pallor, pulselessness, and paralysis. Incomplete and subclinical injuries occasionally occur that initially may be asymptomatic and undetectable. In an unconscious, multiple trauma injured patient, major vascular injuries may not be obvious and may be overlooked. The mechanism of injury and anatomy dictate the need to assess the possibility of an injured vessel. If pulses cannot be palpated, a Doppler stethoscope should be used to detect blood flow. Even the presence of pulses may be misleading however, because pulses may be normal in some patients with significant arterial injuries. When pulses are present, but the mechanism of injury suggests the possibility of a vascular injury, additional diagnostic studies or surgical exploration may be necessary. If a limb is clearly not perfused, operative vascular exploration and repair should be undertaken promptly. Late complications of undiagnosed vascular injuries include thrombosis, arteriovenous fistulae, aneurysm, false aneurysm, and tissue ischemia with limb dysfunction. Delay of vascular injury repair is a risk factor for consequent amputation. The evaluation of peripheral vascular injuries is further discussed in Chapter 40 .

Nerve Injuries

Nerves can be injured by blunt or penetrating orthopedic trauma:

• Neurapraxia is the contusion or traction injury of an otherwise intact nerve, with temporary disruption of the ability to transmit impulses. Paralysis, if present, is transient, and sensory loss is slight. Normal function usually returns to a neurapraxic nerve in weeks to months.

• Axonotmesis is the result of a crush or traction with more severe injury. There is complete interruption of the nerve axon and its myelin sheath, but the mesenchymal structures including perineurium and epineurium are either completely or partially intact. Because the Schwann tubes remain in continuity, spontaneous healing is possible, but delayed.

• Neurotmesis is the severing of a nerve along with its surrounding stroma, usually requiring surgical repair.

When the nerve is completely severed, all functions are absent, including superficial sensation to touch, pain, and temperature; deep sensation to muscle and joint movements; deep pressure, and vibration; motor supply and deep tendon reflexes to distally innervated muscle groups; and response to electrical stimulation. For less severe injuries, any subjective change in sensation should be noted. Light touch is a good screening test. Two-point discrimination is a more sensitive examination and should be used routinely in evaluating digital nerves. The discrimination on the injured digit is then compared with the uninjured ones. A normal two-point discrimination value at the fingertip of an adult is 4 mm, or discrimination may be compared to a non-injured digit. Evaluation of the innervation of the hand is further discussed in Chapter 42 .

The injured nerve, patient age, site, and delay between injury and repair have all been shown to influence prognosis after microsurgical repair. Due to proximity, specific nerve injuries characteristically accompany certain fractures ( Table 41.4 ). For example, in the upper extremity, a distal radius fracture caused by a high-energy insult can be associated with acute dysfunction of the median nerve. Deteriorating or lost neurologic function may necessitate temporary or definitive stabilization of a fracture.

Compartment Syndrome

Compartment syndrome is an acute, emergent complication that should be considered whenever significant pain and paresthesias occur in an extremity following a fracture or crush injury within an enclosed osseofascial space ( Table 41.5 ). Pain is typically severe and out of proportion to the apparent underlying injury. A sense of tenseness may be detected on physical examination. The immediate threat is to the viability of nerve and muscle tissue within the involved compartment, but infection, gangrene, myoglobinuria, and renal failure also may ensue if the diagnosis is not made in a timely fashion. Compartment syndrome is usually associated with a closed long bone fracture of the tibia, but it also is well described in the thigh, forearm, arm, hand, and foot. In addition, compartment syndrome can occur with isolated soft tissue trauma and even with open fractures. It also has been described in a host of unusual situations, including prolonged procedures in the lithotomy position, the tuck position (knees tucked to the chest) for lumbar surgery, coma, spontaneous hemorrhage, extravasation of intravenous injections, and application of excessive traction in treatment of a fracture.