Prospective evaluation of in situ screw fixation for stable slipped capital femoral epiphysis

Purpose: We aimed to determine which variables were associated with persistent symptoms or need for further surgery in patients treated with in situ fixation for stable slipped capital femoral epiphysis. We hypothesized that patients with greater proximal femoral deformity would require revision surgical intervention. Methods: We prospectively collected data on stable slipped capital femoral epiphysis patients who underwent in situ screw fixation at a single institution. Demographic and radiographic information, as well as patient-reported outcomes, were collected. Results: Forty-six patients (54 hips) with an average follow-up of 3.5 years (range: 2.0-8.5) and mean pre-op Southwick slip angle of 40.5 degrees +/- 19.4 degrees were studied. We observed one complication following the index procedure (2%). Twelve hips (22%) went on to have a secondary procedure 2.7 +/- 2.2 years after the index surgery. Severe slips were 14.8x more likely to undergo a secondary procedure than mild and moderate slips (p < 0.001). We found no correlation between slip severity and patient-reported outcomes (p > 0.6). Hips requiring a secondary procedure had significantly lower Hip disability and Osteoarthritis Outcome scores (76.8 +/- 18.4) at final follow-up compared to hips that did not require additional surgery (86.8 +/- 15.7) (p = 0.042). Conclusion: With minimum 2-year follow-up, 22% of patients required a secondary surgery. Patient-reported outcomes did not correlate with slip severity, but were found to be significantly higher in slipped capital femoral epiphysis patients that did not require a secondary procedure. Prophylactic treatment of all slip-related cam deformity was not found to be necessary in this prospective cohort. Patients with moderate-to-severe slips may require secondary surgery.