Vascular supply to slipped capital femoral epiphysis.

The etiology of avascular necrosis associated with slipped capital femoral epiphysis has not been well understood. The aims of this study were to clarify the blood supply to the slipped epiphysis and to examine whether this vascular supply is damaged before the reduction. Twelve patients (12 hips) underwent selective angiography of the medial circumflex femoral artery. There were seven stable slips and five unstable slips. All patients with slips underwent angiography before reduction, and one patient with an unstable slip underwent angiography both before and after reduction. The superior retinacular artery (SRA) was filled in all stable slips. This result was in accordance with the previous report that stable slips result in low rates of avascular necrosis. Of five unstable slips, the SRA was stained in two and was not filled in three. In one slip examined both before and after the manipulative reduction, the SRA was not seen before it but was well stained after it. These results have suggested that in some unstable slips the vascular injury occurs at the time of injury, before reduction, and that the reduction dose not necessarily contribute to the risk of avascular necrosis after slipped capital femoral epiphysis.