Analysis of Risk Factors for Valgus Deformity Following Pediatric Proximal Tibial Metaphyseal Fractures.

BACKGROUND

Delayed valgus deformity, commonly referred to as Cozen phenomenon, is a well-recognized complication following pediatric proximal tibial metaphyseal fractures (PTMFs). This condition may result in gait abnormalities and secondary degenerative changes in the knee joint, with severe cases necessitating surgical correction. This study retrospectively analyzes the risk factors associated with Cozen phenomenon to provide a theoretical basis for its prevention in clinical practice.

METHODS

A retrospective analysis was conducted on pediatric patients with proximal tibial metaphyseal fracture treated with close reduction and casting at our institution from January 2017 to July 2023. At 1-year follow-up, the degree of tibial valgus was quantified using the center of rotation of angulation (CORA), categorizing patients into valgus and nonvalgus groups. Within the valgus group, subgroup analysis based on the severity of valgus deformity was done. Univariate and multivariate regression analyses were used to evaluate the relationship between variables and Cozen phenomenon.

RESULTS

A total of 91 cases were included, with 30 in the valgus group and 61 in the nonvalgus group. Logistic regression analysis revealed that greater difference between the medial and lateral fracture separation lengths (odds ratio [OR] = 4.254, P = 0.015), lateral cortical collapse (OR = 5.099, P = 0.016), and progressive fracture gap widening by callus expansion at 1-month follow-up (OR = 10.566, P = 0.012) were independent risk factors for Cozen phenomenon. Linear regression analysis within the valgus group demonstrated that fracture separation (β = 4.44, 95% confidence interval, 1.932 to 6.949; P = 0.001) and ipsilateral fibular fracture (β = 2.68, 95% confidence interval, 0.042 to 5.319; P = 0.047) markedly influenced the severity of valgus deformity.

CONCLUSION

Differences between medial and lateral fracture separation lengths, lateral cortical collapse, and progressive fracture gap widening by callus expansion at 1-month follow-up are independent risk factors for Cozen phenomenon. Fracture separation and ipsilateral fibular fracture increased the degree of tibial valgus.