VIABILITY OF FEMORAL HEADS IN MASSIVE SLIPPED CAPITAL FEMORAL EPIPHYSIS (SCFE). A REPORT OF SIX CASES

Abstract

Introduction: Avascular necrosis (AVN) is a serious complication affecting the femoral head following an unstable slipped capital femoral epiphysis (SCFE) particularly if the slip is severe. The incidence of AVN may be as high as 47%.

Purpose: To determine whether or not the avascular insult associated with a massive unstable SCFE is a temporary event and whether this may resolve in the second week post injury.

Methods: 6 patients (4 male:2 females), mean age 14.9 yrs (13.2–17.5yrs) with acute severe unstable SCFE were reviewed. The mean Southwick slip angle was 51.20 deg (40.1 – 66.60). 5 of 6 cases were severe. All cases underwent a subcapital cuneiform femoral neck osteotomy at a mean 14 days (7–24 days) after the acute event. Pre-operatively, the hip/limb was rested in ‘slings and springs’. No hip underwent a manipulative procedure. All hips underwent an MRI scan at a mean 8.6 days post injury (range 4–15 days) to determine the viability of the femoral head.

Results: In all 6 cases, the femoral head was reported to be viable. All femoral heads showed signs of bone oedema and other features indicative of a blood supply.

Following the cuneiform osteotomy, patients were mobilized partial weight bearing for 8 weeks. At a mean 12 month follow up, radiographs confirmed that all oste-otomies had united and no hip showed evidence of AVN.

Conclusion: If the acute severe unstable slip is associated with an avascular insult to the femoral head, this may be a temporary phenomenon and assuming the hip is not subjected to any immediate secondary trauma such as operative reduction, then there may be a spontaneous recovery in the blood supply as evidenced by the viable femoral head seen on MRI.

Significance: Our study suggests that there may be a time period during which the slipped femoral head may be vulnerable to a second insult and hence AVN. The timing of any surgical intervention designed at reducing the slip should take this into account and be performed carefully to ensure that the blood vessels on the posterior aspect of the femoral neck are not disrupted. When the presentation of an acute unstable and severe SCFE is delayed beyond 24 hours, we favour delaying subsequent operative correction for a further 2–3 weeks to maximize the chance of a viable femoral head.