Is anterior subcapital shortening osteotomy a reliable and reproducible technique in the treatment of severe slipped capital femoral epiphysis?

INTRODUCTION: Proximal femoral shortening osteotomies are becoming the treatment of choice for severe slipped capital femoral epiphysis (SCFE) to reduce the risk of femoroacetabular impingement. The reported rates of complication seem reasonable, but these are single-operator series with surgeons highly experienced in this technique. The purpose of this study was to assess how surgeon experience impacted the outcomes of anterior subcapital shortening osteotomy (ASSO) in severe SCFE.

HYPOTHESIS: The hypothesis was that ASSO is a reproducible technique that is accessible to junior surgeons.

MATERIALS AND METHODS: All ASSOs performed for severe SCFE (slipangle > 40°) between 2015 and 2019 were retrospectively reviewed. All osteotomies were performed by surgeons with less than 4 years' experience (senior residents), who were trained by a senior surgeon experienced in this technique (Group 1). The incidence of femoral head avascular necrosis (AVN) and complications were analyzed and compared to a historical control cohort (Group 2).

RESULTS: A total of 62 SCFEs (37 unstable and 25 stable) were analyzed. Both groups had similar demographic data and SCFE characteristics. The mean operative times were statistically comparable in both groups. The rates of AVN in unstable SCFEs and in the overall series were comparable in both groups (18.9% vs. 13.3%, p=.55 and 12.9% vs. 9.7%, p=.6). These rates were comparable in the stable forms (4.0% vs. 5.4%; p=1). However, the preoperative MRI in Group 1 showed that 42.8% of unstable hips that developed AVN were already hypoperfused before surgery. The overall rate of complication showed no significant difference between the 2 groups (26% vs. 17%, p=.16).

DISCUSSION: Although ASSO is a technically demanding procedure, it is reliable and reproducible. The main risk factor for developing AVN remains the unstable nature of SCFE and not the surgeon's experience. It can be performed by trained junior surgeons, but not in an emergency setting, with the possibility of assistance from a more experienced surgeon.

LEVEL OF EVIDENCE: IV; retrospective case study.