BACKGROUND

There is growing evidence that symptomatic femoroacetabular impingement (FAI) can develop after severe slipped capital femoral epiphysis (SCFE) fixed in situ. Realignment procedures have therefore gained popularity, but complication rates remain controversial. Among them, the subcapital shortening osteotomy without hip dislocation has been progressively adopted in France, but results have never been assessed to date.

METHODS

All cases performed in 23 French university hospitals between January 2010 and March 2014 were reviewed to (1) describe the surgical procedure, (2) assess the radiologic and functional outcomes, and (3) report complications and more specifically the avascular necrosis rate (AVN) according to initial stability. Stable and unstable SCFE were distinguished following Loder's definition. Radiologic outcomes were assessed by the 3 authors to determine FAI and osteonecrosis rates. Functional outcomes were evaluated at follow-up and complications were reported.

RESULTS

A total of 82 cases (45 unstable and 37 stable), performed in 10 institutions, were included with a mean follow-up of 25 months. No intraoperative complication occurred but 2 patients (2.4%) underwent unplanned early revision. Slip angle was significantly reduced (87%) without loss of correction. Overall AVN rate was 9.7%, reaching 13.3% in unstable slips. However, preoperative magnetic resonance imaging showed that most of the unstable epiphyses (4/6) were already hypoperfused before surgery.

CONCLUSIONS

The procedure is a reliable option for the treatment of severe SCFE. AVN rates are lower than previously reported in multicenter series of modified Dunn technique, especially in unstable slips. However, the risk of AVN in severe stable SCFE (5.4%) must still be balanced with the functional outcomes of potential future FAI.

LEVEL OF EVIDENCE

Level IV-therapeutic study.