The presentation is variable, based on severity and type of slip. Patients will often report hip or knee pain, limp or inability to ambulate, and decreased hip range of motion. There may or may not be a traumatic event. Any knee pain mandates an examination of the hip, as hip pathology can cause referred pain to the anterior thigh and knee along the obturator nerve. The patient usually holds the affected extremity in external rotation. As the hip is flexed, it will progressively externally rotate. There is usually a limitation of internal rotation, but there may also be a loss of flexion and abduction. If the patient can bear weight, it is typically an antalgic gait with the affected leg in external rotation. It is important to examine both hips to determine bilateral involvement.
Anteroposterior and frog-leg radiographs are indicated.Patients with known SCFE or with a high index of suspicionshould not undergo frog-leg lateral radiographs. Instead, a crosstable lateral radiograph reduces the risk of iatrogenic progression. The earliest sign of SCFE is widening of the physis withoutslippage (preslip condition). Klein’s line (Fig. 199-4) is helpfulin assessing the anteroposterior radiograph for SCFE. The slippage can be classified radiographically as type I (0% to 33% displacement), type II (34% to 50%), or type III (>50%). The likelihood of complications increases with degree of displacement.
Patients with SCFE should be immediately made non–weight bearing and referred to a pediatric orthopedist. The goal is to prevent further slippage, enhance physeal closure, and minimize complications, which is usually accomplished with internal fixation in situ with a single cannulated screw. More severe cases may require surgical hip dislocation and reduction to realign the epiphysis. There is controversy surrounding the prophylactic fixation of the nonaffected side. Assessment for endocrine disorders is important, particularly in children outside the range of 10 to 16 years of age.
Figure 199-4 Slipped capital femoral epiphysis (SCFE). A, Anteroposterior radiograph reveals a widened physis (small arrows) and decreased height of the epiphysis on the left. In addition, there is loss (large arrow) of the Capener triangle (c) (normal double density of the medial metaphysis superimposed on the posterior acetabular rim on right) and an abnormal lateral femoral neck line (normal on right). B, Frog, lateral view confirms the inferomedial position of the SCFE. (From Blickman H: Pediatric Radiology, the Requisites, ed 2, St Louis, 1998, Mosby, p 244.)
The two most serious complications of SCFE are chondrolysis and avascular necrosis. Chondrolysis is destruction of the articular cartilage. It is associated with more severe slips and with intra-articular penetration of operative hardware. This can lead to severe osteoarthritis (OA) and disability. Avascular necrosis occurs when there is a disruption of the blood supply to the capital femoral epiphysis. This usually happens at the time of injury, but may occur during forced manipulation of an unstable slip. Avascular necrosis may occur in up to 50% of unstable SCFEs and may lead to OA.
Torsional (in-toeing and out-toeing) and angular (physiologic bowlegs and knock knees) variations in the legs are common reasons that parents seek medical attention for their child. Most of these concerns are physiologic and resolve with normal growth. Understanding the natural history allows physicians to reassure the family and to identify nonphysiologic disorders that necessitate further intervention. Physiologic disturbances are referred to as variations; pathologic disturbances are called deformities.