Management of Pediatric Femoral Neck Fracture

Joseph T. Patterson, MD; Jennifer Tangtiphaiboontana, MD; Nirav K. Pandya, MD

Disclosures

J Am Acad Orthop Surg. 2018;26(12):411-419. 

In This Article

Complications

The reported overall complication rate after management of femoral neck fracture is approximately 33%.[28] Osteonecrosis is the most common complication; other complications include premature physeal closure, coxa vara deformity, the need for revision surgery, nonunion, surgical site infection, septic arthritis, posttraumatic slipped capital femoral epiphysis (SCFE), and overgrowth of the femoral neck.[7,28]

Osteonecrosis

Osteonecrosis is the most common and debilitating complication of traumatic pediatric femoral neck fractures, occurring in 20% to 29% of patients after surgical reduction and fixation.[7,16,25,26] Development of osteonecrosis is associated with fracture displacement, fracture location (Delbet types I and II), and closed management via casting or closed reduction with internal fixation.[16,26] Spence et al[16] reported that osteonecrosis was nine times as likely to develop in the setting of displaced fractures compared with nondisplaced fractures. In the setting of Delbet type I and II fractures, development of osteonecrosis was 14 times and 4 times more likely, respectively, compared with type III fractures. The reported rates of osteonecrosis according to the Delbet classification are 38% to 50% for type I, 28% for type II, 8% to 18% for type III, and 5% to 10% for type IV.[25,35] Age >10 years also has been shown to be a factor in increased risk of osteonecrosis.[25,28,35] Although several studies linked osteonecrosis with capsular decompression, open fixation method, fracture alignment after reduction and fixation, and injury mechanism,[7,19,27] recent studies and meta-analyses have not supported these findings.[7,9,16,26] The relationship between time to open surgical fixation and the development of osteonecrosis remains unclear, with higher rates of osteonecrosis reported in the setting of early and late fixation.[9,15,16,24,29] Osteonecrosis has led to coxa vara deformity in 6% to 33% of cases managed nonsurgically.[1,2,6] In a study of six patients with osteonecrosis associated with femoral neck fractures, core biopsies of the fracture site at the time of device removal demonstrated empty trabecular lacunae and bone marrow necrosis in patients with minimally displaced fracture with incomplete repair >1 year after injury.[36]

Osteonecrosis is most likely the result of vascular injury that occurs at the time of fracture. Proposed mechanisms include kinking or direct laceration of the blood vessels or ischemia from tamponade of the vessels as a result of an increase intracapsular pressure. Inconclusive evidence exists in the current literature to support urgent reduction and fixation with capsular decompression to reduce the risk of osteonecrosis. The median time to development of osteonecrosis is 7.8 months from injury (range, 2.7 to 31.4 months), but osteonecrosis can take up to 2 years to develop.[16] Therefore, patients should be followed closely, with annual radiographs obtained until the patient reaches skeletal maturity.[7,16] If early signs of osteonecrosis are present on plain radiographs, MRI with metal subtraction sequences can be obtained. Ratliff[5] characterized osteonecrosis of the hip as involvement of the entire femoral head (type I), confinement to segments of the head (type II), or involvement of the femoral neck (type III). Prognosis and management options vary depending on the type of osteonecrosis, the degree of deformity and collapse, and the age at which the condition becomes symptomatic. If detected early, osteonecrosis can be managed with anti-inflammatories, physical therapy, and limitation of impact activities.

Septic Arthritis

Postoperative infection is a rare complication of hip fractures in children, occurring in up to 5.2% of patients.[1,2,7] Infection has been reported after both open and closed reduction with percutaneous fixation.[37] Early diagnosis and management of infection with antibiotics and wound débridement may improve outcomes and prevent sequelae such as osteomyelitis, osteonecrosis, premature physeal closure, and chondrolysis.

Nonunion

Nonunion, which is defined as failure of fracture healing after 4 to 6 months of treatment, has been reported in up to 10% of pediatric patients with femoral neck fractures and is most common in patients with type II fractures and least common in those with type IV fractures.[7] Fractures that were not anatomically reduced or in which fixation was either inadequate or failed may also result in nonunion. Management of nonunions involves a valgus osteotomy to convert shear forces to compressive forces and to promote fracture healing.[38] Fibular osteosynthesis also has been described as a management option for nonunion; however, this method does not address any coxa vara deformity that commonly occurs with fracture nonunion.[39]

Coxa Vara

Early studies of pediatric femoral neck fractures noted that malunion leads to limp, femoroacetabular impingement, early arthritis, and progressive disability.[13] Coxa vara deformity, which is defined as a femoral neck-shaft angle of <120°, is a common complication of femoral neck fractures in children, with a reported incidence of up to 18%.[7] Although mild coxa vara deformity in young children may remodel with growth, more severe deformity may require surgical correction. Magu et al[38] reported that a valgus Pauwels intertrochanteric osteotomy can produce good results (eg, high rates of union and deformity correction) and may have a role in restoring the viability of the femoral head in the setting of osteonecrosis.

Premature Physeal Closure

Reports of premature physeal closure after hip fracture vary widely, with an incidence ranging from 20% to 62%.[1,2,5–7] Mechanisms of injury include direct trauma to the physis or injury to the blood supply, either from the fracture itself or surgical management. Partial premature physeal arrest may result in coxa vara and coxa valga deformities of the proximal femur. The assessment of premature physeal closure before the development of deformity or limb-length discrepancy may be difficult; however, MRI may be helpful to detect physeal injuries and bar formation, providing better prognostic information.[40] The proximal femoral physis contributes approximately 15% of the overall length of the femur. Complete physeal closure in very young children (aged <10 years and/or with >2 years of growth remaining) may result in a substantial limb-length discrepancy (>2 cm). Older children and adolescents with premature physeal closure may go on to have a clinically significant limb-length discrepancy. Patients with a limb-length discrepancy of <2 cm may be treated nonsurgically with a shoe lift; however, those with a larger limb-length discrepancy may require epiphysiodesis of the distal femur and/or proximal tibia of the contralateral limb.

Posttraumatic SCFE and Overgrowth of the Femoral Neck

Delayed SCFE is another complication of femoral neck fracture. In a small series of Delbet type II and III femoral neck fractures treated surgically, Li et al[41] observed this complication at an average of 9 months after fracture management (range, 5 weeks to 15 months). The delayed SCFE may have been a result of implant irritation, premature initiation of weight bearing, coxa vara deformity, osteonecrosis, delayed union, or nonunion.

Overgrowth of the femoral shaft after fracture has been well described in the pediatric population, but little attention has been paid to overgrowth of the femoral neck after fracture. Kuo et al[42] reported on a series of 30 femoral neck fractures in 30 patients, in which 12 patients demonstrated an average femoral overgrowth of 6.2 mm. Patients with overgrowth were younger (mean age, 5.5 years versus 9.9 years), had a lower rate of osteonecrosis, and had better functional outcomes.

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