The unstable slipped capital femoral epiphysis: does the rate of osteonecrosis really depend on the timing of surgery and surgical technique?

To investigate whether the timing of surgery and surgical technique affect the rate of osteonecrosis in unstable slipped capital femoral epiphysis (SCFE). This is a retrospective review of all unstable slips that were treated at our institution over 8.5 years with a minimum follow-up period of 12 months. Patients with stable slips were excluded from this analysis. Demographic data, time to surgery, and surgical technique were analyzed. Twenty-three unstable slips were included for study after excluding 40 stable slips. There were 17 males and six females, with an average age of 11.9 years; 13 patients had right SCFEs. The average time from diagnosis to surgery was 57.7 h. Nine (39.1%) surgeries were performed within 24 h of admission, whereas 14 (60.9%) surgeries were performed after 24 h. Minimum follow-up was 23 months. Two patients developed osteonecrosis: one underwent surgery within 24 h of admission and the other after 24 h. Both underwent in-situ screw fixation. In the group that did not develop osteonecrosis, 76.2% underwent in-situ screw fixation and 23.8% underwent manipulative reduction. The rate of developing osteonecrosis following screw fixation in unstable SCFE was unrelated to whether surgery was performed before or after 24 h of admission (P=1.0), or whether in-situ screw fixation or manipulative reduction pre-fixation was performed (P=0.605). The results of this small series challenge the practice of stabilizing unstable SCFEs emergently and the belief that gentle manipulative reduction pre-fixation is not recommended because it may increase the rate of osteonecrosis. Level of Evidence: Level IV Evidence.