Factors Associated With Premature Physeal Closure After Distal Femur Physeal Fracture.

Background: Premature physeal closure (PPC) after distal femur fractures is a recognized complication. To date, risk factors for PPC have not been well identified. This study's purpose is to identify risk factors for this challenging problem and start the discussion for changing practice guidelines in high-risk patients.

Methods: A retrospective review of displaced distal femur physeal fractures undergoing surgical stabilization at a single, level I pediatric hospital were identified between 2011 and 2022. Patient charts were reviewed and injury, radiographic, and surgical data were recorded. Univariable statistical analysis was performed to identify factors associated with PPC. Odds ratios were calculated and binary logistic regression was utilized to determine the odds of PPC based on risk factors present.

Results: Fifty-four patients were identified with a mean chronologic age of 13±3 years, a mean bone age of 14±3 years, and the majority were male (67%). Twenty-eight percent of the cohort presented with severe fracture displacement. The interposed periosteum was removed in 37% of patients. The overall rate of PPC was 48% (N=26) and 77% of these underwent subsequent surgical intervention. When the PPC was identified at the 6-month postinjury visit (n=26), 50% had already developed a leg length discrepancy (LLD) of at least 1 cm. Three nonmodifiable factors were significantly associated with PPC: bone age, Salter-Harris (SH) type, and fracture displacement. The risks of PPC based on the number of factors present compared with zero factors were: 1 factor odds ratio (OR)=4.4 (95% CI: 0.4-45, P=0.22), 2 factors OR=39 (95% CI: 3.8-399, P=0.002), and 3 factors OR=96 (95% CI: 5.2-1767, P=0.002). Patients with 2 and 3 risk factors had a 77% and 89% rate of closing early.

Conclusion: Premature physeal closure frequently occurs after distal femur physeal fractures and risk factors include younger bone age, SH I and II fractures, and fractures with greater initial displacement. When multiple risk factors are present, the odds of PPC are high, and intervention before 6 months could be considered to avoid a resultant LLD ≥1 cm or angular deformity. A larger study is warranted to create a predictive model and to enhance the precision of the risk factor analysis.