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.