Abstract
BACKGROUND: The risk factors for avascular necrosis (AVN) in patients with unstable slipped capital femoral epiphysis (SCFE) were controversial and multifactorial. This meta-analysis summarizes existing evidence to identify risk factors for AVN. METHODS: Search strategies followed the recommendations of the Cochrane Collaboration. Electronic searches such as PubMed, Embase, Web of Science, Cochrane were systematically searched for publications concerning risk factors for unstable SCFE from the inception date to October 2024. The RevMan 5.3 software and Stata 17.0 software were used for the meta-analysis. Finally, publication bias and sensitivity analysis were carried out. RESULTS: This study included 16 articles involving 688 hips. We found that the overall incidence of AVN was 23%. Our research indicated that male gender (OR = 2.37; 95% CI = 1.23 to 4.58, P = 0.01), the moderate and severe slip (OR = 0.09; 95% CI = 0.02 to 0.37, P < 0.001), the acute slip (OR = 3.93; 95% CI = 1.55 to 9.95, P = 0.004), reduction (OR = 0.87; 95% CI = 0.24 to 3.20, P = 0.84) especially closed reduction (OR = 4.33; 95% CI = 1.09 to 17.28, P = 0.04) were important risk factors for postoperative AVN, while age (MD = -0.58;95% CI = -1.34 to 0.18, P = 0.13), the side of hip (OR = 0.89; 95% CI = 0.44 to 1.80, P = 0.74), the number of implants (OR = 0.87; 95% CI = 0.24 to 3.20, P = 0.84), delayed surgery (OR = 0.64; 95% CI = 0.38 to 1.09, P = 0.10) and capsular decompression (OR = 0.80; 95% CI = 0.32 to 1.99, P = 0.63) were not. CONCLUSIONS: In summary, the pooled incidence of AVN after unstable SCFEs was 23% and the available evidence demonstrated that being male, having a moderate or severe slip (slip angle ≥ 30°), having an acute slip (symptoms ≤ 3 weeks), and undergoing reduction, especially closed reduction, are important risk factors for postoperative AVN. LEVEL OF EVIDENCE: IV. This study was registered as PROSPERO 2024 CRD42024566661.