Objective: To study the most important risk factors for avascular necrosis (AVN) and chondrolysis in children with slipped capital femoral epiphysis (SCFE).
Material and Method: Thirty patients with SCFE, who were surgically treated by single-screw fixation with good positioning from 1998 to 2012, were reviewed (22 male and 8 female patients, 35 hips; bilateral involvement in 1 male and 4 female patients). The following clinical and radiographic data were analyzed: age, sex, weight, height, onset, grading, stability, severity, history of trauma, anterior physeal separation (APS), and major complications such as AVN and chondrolysis. The results were reported according to the Heyman and Herndon criteria as excellent, good, fair, poor, or failure. Multiple logistic regression was used to identify multivariate predictors of osteonecrosis and chondrolysis.
Results: The mean patient age was 11.9 years. The right and left sides were affected in 45.7% and 54.3% of patients,
respectively. There were 2 acute (5.7%), 26 chronic (74.3%), 5 acute-on-chronic (14.3%), and 2 preslips (5.7%). Five hips were unstable (14.3%), and 30 were stable (85.7%). There were 14 mild slips (40%), 6 moderate slips (17.1%), and 15 severe slips (42.9%). Thirteen hips (37.1%) had a history of trauma. APS was present in 12 hips (34.3%). Nine hips had AVN (25.7%), 7 had chondrolysis (20.0%), and 10 had both AVN and chondrolysis (28.6%). Clinical results were excellent, good,
fair, poor, and failure in 13 (37.1%), 12 (34.3%), 6 (17.1%), 2 (5.7%), and 2 hips (5.7%), respectively. Univariate analysis revealed that the statistically significant risk factors (p<0.05) for AVN and chondrolysis were the presence of APS (p = 0.000), acute and acute-on-chronic onset (p = 0.001), moderate and severe grades (p = 0.002), instability (p = 0.17), and a history of trauma (p = 0.02). Multivariate analysis revealed that the presence of APS was the only risk factor for AVN and chondrolysis with the highest statistical significance (p = 0.000).
Conclusion: Single-screw fixation gave good and reliable outcomes in most cases. APS is the most important risk factor for AVN and chondrolysis in patients with SCFE. The optimal alternative treatment to reduce this major complication should be further studied, especially in patients with acute or acute-on-chronic slips, unstable hips, a history of trauma, or APS.

Keywords: SCFE, AVN, Chondrolysis, Risk factors, APS