Slipped capital femoral epiphysis (SCFE) involves the posterior slippage of the proximal femoral epiphysis caused by mechanical shearing forces, with concomitant extension and external rotation of the femoral neck and shaft (Fig. 4). It is regarded as the most common hip disorder of adolescence, with a increased prevalence among males, and with peak onset around 11 years of age . Increased body mass index (BMI) is a significant risk factor for the development of slipped capital femoral epiphysis, with both biomechanical and endocrinologi-cal factors implicated.
Classification of slipped capital femoral epiphysis has traditionally been based on acuity of symptoms and severity of the slip; however, a greater emphasis is now being placed on mechanical stability because of its greater prognostic value. A mechanically stable slip will allow weight-bearing, whereas a patient who has an unstable SCFE typically represents an acute physeal fracture, with concomitant microscopic instability resulting in pain and an inability to bear weight.
Fig. 4. Anteroposterior pelvis radiograph demonstrating a left mild stable slipped capital femoral epiphysis.
Accurate, early diagnosis of SCFE is important in preventing both short-term complications, including chondrolysis and avascular necrosis of the femoral head, and longer-term problems such as hip dysfunction and osteoarthritis. The insidious and often ambiguous onset of symptoms, combined with the absence of radiological changes early in the condition, are common causes of delayed diagnosis. Symptoms associated with a stable slip typically involve a dull ache that is exacerbated by exercise, but can be localized anywhere from the groin to the medial aspect of the knee. The delayed onset of significant pain and dysfunction may allow for the progression from a stable to unstable slip, with major implications for long-term prognosis.
Management of SCFE is fraught with challenges, especially for severe slips caused by significant deformity of the femoral head, and there is inherent risk of iatrogenic avascular necrosis and subsequent osteoarthritis. A number of potential risks factors of avascular necrosis have been reported, including the use of multiple pins, pin position and penetration, complete or partial reduction, and the stability and severity of slip. Unfortunately, at present there is little in the literature regarding the optimal management of acute, unstable SCFE. A recent survey of Pediatric Orthopaedic Society of North America (POSNA) members found that 57% reported using a single threaded screw for fixation for unstable SCFE, whereas 40.3% recommended three threaded screws .
There is a clear relationship between the stability and severity of the slip and subsequent postoperative risk of osteonecrosis. Patients who had stable lesions showed no increase in risk of osteonecrosis, whereas those who had unstable lesions demonstrated an increased level of risk that was proportional to the grade or severity of the slip. In situ pinning without reduction using a single cannulated screw was associated with the lowest risk of iatrogenic osteonecrosis of the femoral head, irrespective of stability or severity of slip .
Bilateral SCFEs have been reported to occur in 20% to 50% of cases, though simultaneous presentation is unusual . Despite this high incidence, the optimal management of the contralateral hip when presented with a unilateral SCFE remains controversial .
Was this article helpful?