Acute, unstable, slipped capital femoral epiphysis: is there a role for in situ fixation?

BACKGROUND: Slipped capital femoral epiphysis, a common disorder in adolescents, may be increasing in incidence in North America because of the obesity epidemic. In most cases, the slip is mild and can be treated with in situ fixation. Even in more severe cases of a stable slip, in situ fixation remains a widely accepted choice. When the slip is acute and unstable, treatment remains controversial. We reviewed the orthopaedic literature and our personal experience in managing acute, unstable slipped capital femoral epiphysis. The reported range of avascular necrosis (AVN) is high and the literature shows no clear recommendations for the best treatment choice. Treatment choices include: in situ stabilization with possible later corrective osteotomy, formal manipulative closed reduction plus screw fixation, partial reduction through an open approach with the hip joint decompressed (Parsch method), and anatomic reduction by the modified Dunn method. Review of the literature and our experience suggests a high AVN rate in acute unstable slips no matter what treatment method is selected. Most North American reports suggest an AVN rate with in situ screw fixation ranging from 20% to 50%. The method described by Parsch, which includes an urgent, open capsulotomy, joint decompression, and gentle partial reduction, shows a low AVN rate as reported from his institution (<10%). The AVN rate reported for anatomic reduction (modified Dunn procedure) performed through an open surgical hip dislocation was initially quite low, but after being restudied in North American centers appears to be about 25%.

CONCLUSIONS: Safe treatment of an acute unstable slip remains problematic. The literature suggests that these patients should be treated urgently; however, simple in situ stabilization results in a high AVN rate. A likely safer modification is to open the hip anteriorly to decompress the joint and to stabilize after partial reduction as described by Parsch. The modified Dunn method is becoming more widely used, but results in North American centers cite a significant AVN rate.