Common Fractures of the Lower Extremities

CHAPTER 45

Common Fractures of the Lower Extremities

Femoral Shaft Fractures

INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY

• Femoral shaft fractures account for 1.4% to 1.7% of all pediatric fractures.

• Incidence is highest between 2 and 3 years of age and in mid-adolescence

• Incidence is 2.6 times higher in boys than in girls

• The most common mechanism in early childhood is a fall.

• The most common mechanisms in adolescence are sports and motor vehicle accidents.

• In preambulatory children and infants, femoral shaft fractures are commonly caused by intentional trauma (nonaccidental). After walking age, most are accidental. Nonaccidental trauma must be carefully considered in the differential diagnosis up to age 3 years.

• Pathologic fractures can occur with osteogenesis imperfecta, tumor, infection, or osteopenia.

SIGNS AND SYMPTOMS

• Thigh pain, swelling, deformity, limb shortening, and inability to bear weight after acute trauma

• Can be associated with significant bleeding within the thigh, although unlike in adults, the need for blood replacement is rare

DIAGNOSTIC CONSIDERATIONS

• Anteroposterior (AP) and lateral radiographs of the femur that include the hip and knee joints are sufficient to establish the diagnosis (Figure 45-1).

TREATMENT

• Treatment depends on the age and size of the patient.

• Infants are treated with a single-leg spica cast or soft spica (ie, thick cotton roll padding without plaster or fiberglass) for 4 weeks. Up to 45 degrees of angulation is acceptable, given the capacity for remodeling.

Figure 45-1. A, Anteroposterior view of the femur in a young (aged 2 to 4 years) child shows a spiral fracture of the distal third of the femur with mild lateral displacement (arrows). B, Lateral view of the femur in the same patient shown in A shows a spiral fracture of the distal third of the femur with mild anterior displacement (arrow).

From Johnson TR, Steinbach LS, eds. Essentials of Musculoskeletal Imaging. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2004:863. Reproduced with permission.

• Children 5 years and younger are most commonly treated with intraoperative closed reduction and spica casting for up to 6 weeks.

• Children between 6 and 10 years of age may be treated in a variety of ways, including immobilization in a spica cast for 8 weeks, although the current preferred method is flexible intramedullary nail fixation.

• Larger patients and young adults

— Because of greater risk for complications such as loss of fracture position with the flexible nail, rigid intramedullary rod fixation is often used.

— The “adult” piriformis fossa technique for inserting a rigid nail carries a risk of osteonecrosis. Patients with open growth plates are treated with insertion of a rigid nail through a special “lateral entry.”

— Alternative methods of treatment include submuscular plates and external fixation.

EXPECTED OUTCOMES/PROGNOSIS

• Most femoral shaft fractures heal well without complications or long-term disability.

• Potential complications include angular and rotational deformities, nonunion (rare), infection, muscle weakness, and leg-length discrepancy (most common).

— In children between 2 and 10 years of age, leg-length discrepancy most commonly results from overgrowth of the injured side caused by growth acceleration.

— Patients older than 10 years are more likely to have shortening of the injured side.

— Patients with leg-length discrepancy less than 2 cm generally notice no alteration in their stride or knee mechanics, and do not typically develop back pain.

WHEN TO REFER

• Promptly refer all pediatric femur fractures to an orthopaedic surgeon.

• Temporary immobilization with a splint from buttock to mid-calf offers excellent restoration of alignment and analgesia (Figure 45-2).

• Refer cases of suspected physical abuse to the appropriate local authorities. These would include especially preambulatory infants without bone disease and children younger than age 3 years without plausible history. Note that the fracture pattern is not helpful in the diagnosis of nonaccidental trauma and specifically that spiral fractures of the femoral shaft in ambulatory children are typically accidental, not inflicted.

Figure 45-2. Posterior mold splint.

• Skeletal surveys should be performed for infants with suspected abuse-related femoral fractures.

Distal Femoral Physeal Fractures

INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY

• Distal femoral physeal fractures account for approximately 5% of all physeal fractures.

• These injuries usually result from high-energy trauma to a hyperextended knee, leading to anterior displacement of the epiphysis.

• Most are Salter-Harris type I or II (see Chapter 42, Physeal Fractures, Figure 42-1, for an illustration of the Salter-Harris classification system).

• They are associated with a high potential for growth arrest and future problems.

SIGNS AND SYMPTOMS

• Knee pain, swelling, limited range of motion, and inability to bear weight

• Tenderness over the distal femoral growth plate

• Careful neurovascular examination is performed to rule out injury to the popliteal artery or sciatic nerve.

DIAGNOSTIC CONSIDERATIONS

• AP and lateral radiographs of the knee are usually sufficient to establish the diagnosis.

• A notch or tunnel view may be necessary to identify Salter-Harris type III fractures.

TREATMENT

• Anatomic reduction is required for Salter-Harris type II, III, and IV fractures because even a small amount of physeal displacement can result in formation of an osseous bar, increasing the risk for limb-length discrepancy or angular deformity.

• Closed reduction may be possible for minimally displaced fractures, although screw or pin fixation is advisable for most of these unstable injuries.

EXPECTED OUTCOMES/PROGNOSIS

• Approximately 50% result in leg-length discrepancy or angular deformity caused by formation of osseous bars that bridge the physis

• Loss of joint motion is a less common complication.

WHEN TO REFER

• Promptly refer all distal femoral physeal fractures to an orthopaedic surgeon.

Proximal Tibial Physeal Fractures

INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY

• These injuries are rare, with a high rate of complication.

• They usually result from a direct blow to the lateral aspect of the knee or from a hyperextension injury.

SIGNS AND SYMPTOMS

• Knee pain, swelling, and inability to bear weight after acute trauma

• Tenderness over the proximal tibial growth plate

DIAGNOSTIC CONSIDERATIONS

• AP and lateral radiographs of the knee are initially sufficient to establish the diagnosis.

• Careful neurovascular examination should be performed to rule out injury to the popliteal artery or sciatic nerve.

TREATMENT

• Non-displaced fractures are usually treated in a long-leg cast with the knee flexed approximately 15 degrees.

• Displaced fractures are treated with closed or open reduction with cast or pin fixation and must be meticulously evaluated pre- and postoperatively because of the high risk for vascular injury and compartment syndrome.

EXPECTED OUTCOMES/PROGNOSIS

• These patients must be followed for several years because they are at high risk for angular deformity or leg-length discrepancy caused by physeal arrest.

WHEN TO REFER

• Promptly refer all proximal tibial physeal fractures to an orthopaedic surgeon.

• Emergently refer all displaced proximal tibial physeal fractures.

Tibial Tubercle Avulsion Fractures

INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY

• Avulsion of the tibial tubercle apophysis is caused by sudden, forceful contraction of the quadriceps.

• This type of fracture accounts for less than 3% of physeal injuries.

• They are most common during adolescence (ie, 14–16 years of age).

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