Increased acetabular depth may influence physeal stability in slipped capital femoral epiphysis.

BACKGROUND: Multiple mechanical factors affecting the hip have been associated with the development of slipped capital femoral epiphysis (SCFE). Whether acetabular depth plays a role in the development of a SCFE has not been elucidated.

QUESTIONS/PURPOSES: (1) What is the prevalence of a deep acetabulum in SCFE? (2) Is the presence of a deep acetabulum associated with physeal instability? (3) Is the presence of a deep acetabulum associated with the occurrence of a contralateral SCFE?

METHODS: We retrospectively reviewed 232 patients (156 males) who presented with a unilateral SCFE. Fifty (22%) subsequently developed a contralateral SCFE. The involved and uninvolved sides were evaluated for the presence of a deep acetabulum (DA). Preoperative radiographic parameters, slip stability, development of a contralateral SCFE, and demographic factors were then compared between patients with and without DA.

RESULTS: DA was present in 120 hips (52%) with a SCFE. DA was more common in females (55 of 76 [72%]) than males (65 of 156 [42%]). Patients with DA presented with a higher lateral center-edge angle (33° versus 31°), slip angle (52° versus 43°), and with a lower body mass index (28.1 versus 30.0 kg/m(2)). Increased acetabular depth was more common in patients with an unstable SCFE (29 of 41 [71%]) than those with a stable SCFE (91 of 191 [48%]). The presence of DA either on the affected side or the contralateral side did not predict a contralateral SCFE.

CONCLUSIONS: Despite not predicting a contralateral SCFE, DA may influence physeal stability if a SCFE does develop. Therefore, the contralateral hip with DA should be closely monitored.

LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.