Background: In slipped capital femoral epiphysis (SCFE), urgent screw fixation with or without incidental reduction is recommended for mild to moderate slips to prevent progression and reduce the risk of osteonecrosis. Residual proximal femoral deformity often persists despite fixation, predisposing to femoroacetabular impingement (FAI). This study investigated disease-related and surgical factors associated with residual proximal femoral deformity.

Methods: We retrospectively reviewed patients with SCFE who underwent percutaneous screw fixation between 2003 and 2023. Demographic variables (age, sex, weight, chronicity, stability) and surgical details (screw number, screw depth, screw position, immediate postoperative alignment) were collected. Residual deformity was assessed using alpha angles at a minimum follow-up of 12 months. Multivariable regression was performed to evaluate associations between disease- and surgery-related factors and residual deformity.

Results: Fifty-six hips from 49 patients were analyzed (mean age 11.6 ± 2.9 years; 64.3% male; 65.5% chronic; 85.7% stable) with a mean follow-up of 3.7 years. Multivariable regression analysis demonstrated that greater weight (β = 0.31°/kg), chronic slip (β = 7.33°), acute-on-chronic slip (β = 7.48°), and larger postoperative Southwick angle (β = 0.42°/degree) were associated with increased alpha angle. In contrast, stability (β = –11.9°), higher screw number (β = –16.1°), superior screw deviation (β = –0.55°/mm), and posterior screw deviation (β = –0.56°/mm) were associated with reduced alpha angle.

Conclusion: Residual proximal femoral deformity after SCFE fixation was influenced by both disease-related (weight, chronicity, stability, postoperative Southwick angle) and surgical (screw number and position) factors. These findings highlight the combined effect of underlying pathology and surgical technique, suggesting that careful screw placement may mitigate residual deformity and its potential long-term consequences.

Kittiphot Sophonrat is a pediatric orthopaedic fellow at the Department of Orthopaedics, Faculty of Medicine, Siriraj Hospital, Mahidol University, Thailand. He completed his Doctor of Medicine at Khon Kaen University and obtained Thai Board certification in Orthopaedic Surgery. His academic interests focus on pediatric orthopaedics, fracture management, and outcomes research. He has presented research at national orthopaedic meetings and is currently involved in studies on pediatric hip disorders and fracture-related complications.