Treatment of Unstable Slipped Capital Epiphysis Via the Modified Dunn Procedure

The modified Dunn procedure has been shown to be safe and effective in treating unstable slipped capital femoral epiphysis (SCFE). We present a consecutive series of unstable SCFE managed by a single surgeon with a focus on timing of surgical intervention, postoperative complications, and radiographic results.

Thirty-one consecutive unstable SCFEs were treated. Demographics, presentation time to time of operation, surgical times, and complications were recorded. Bilateral hip radiographs at latest follow-up were utilized to record slip angle, α angle, greater trochanteric height, and femoral neck length.

Thirty-one consecutive hips in 30 patients were reviewed: 15 males (50%) and 15 females (50%), average age 12.37 years (range, 8.75 to 14.8 y), 20 left hips (65%) and 11 right hips (35%). Mean follow-up was 27.9 months (range, 1 to 82 mo). Time from presentation to intervention averaged 13.9 hours (range, 2.17 to 23.4 h). Two patients (6%) developed avascular necrosis at average 19 weeks postoperative. Three patients (10%) developed mild heterotopic ossification requiring no treatment. Two patients (6%) required removal of symptomatic hardware. One patient had hardware failure and in no patients was nonunion, delayed union, or postoperative hip subluxation/dislocation seen. Three patients (10%) presented with bilateral, stable SCFE requiring contralateral in situ pinning. Five patients (16%) had sequential SCFE requiring treatment with 1 patient having an acute, unstable SCFE 10 months after the previous realignment. Mean postoperative slip angle measured 2.5 degrees (range, +19 to -9.4 degrees) (SD, 7.2), α angle 47.43 degrees (range, 34 to 64 degrees) (SD, 7.49), greater trochanteric height averaged 3.5 mm below the center of femoral head (-17.5 to +25 mm), and mean femoral neck length difference measured -7.75 mm (range, -1.8 to -18.6 mm).

A single surgeon series of unstable SCFEs treated by a modified Dunn procedure showed a 6% incidence of avascular necrosis and low complication rates at latest follow-up. Radiographs showed restoration of the slip angle, α angle, femoral neck length, and greater trochanteric height. This series reveals the safety and effectiveness of the modified Dunn procedure for unstable SCFE.

Level III-retrospective review.