Analysis of Intraoperative and Postoperative Hinge Fractures of Patients With Genu Valgum Treated With Lateral Open Wedge Distal Femoral Osteotomy.

Abstract

Objective: Hinge fracture is a known complication of lateral open wedge distal femoral osteotomy (LOWDFO). However, few studies have differentiated between intraoperative hinge fractures (IHF) and postoperative hinge fractures (PHF). This study aims to investigate the causes of these two types of fractures to help reduce complication rates and improve surgical outcomes.

Methods: We retrospectively analyzed data from 100 patients with genu valgum deformity and lateral unicompartmental osteoarthritis who underwent distal femoral osteotomy at our hospital between January 1st, 2022, and January 1st, 2024, in our hospital. Clinical parameters, radiological data, and the associated factors influencing IHF and PHF were analyzed. Radiological data such as mechanical axis deviation (MAD) and mechanical lateral distal femur angle (mLDFA) were collected. Clinical outcomes such as osteoarthritis index and time of healing were evaluated. Based on fracture morphology, IHF and PHF were further classified into Type 1 (extension), Type 2 (distal) and Type 3 (proximal) for detailed analysis. Statistical analyses included t-tests, Chi-square tests, and regression models to identify factors associated with IHF and PHF.

Results: A total of 87 patients were included in this study. The mean healing time of patients with all kinds of hinge fractures (3.4 ± 1.2 months) was longer than that of patients with no hinge fractures (2.8 ± 0.7 months), which was significant, p = 0.013. The MAD correction, mLDFA correction, and mLDFA correction ratio were related to hinge fractures (p = 0.010, 0.002, and 0.002 respectively). The body weight was higher in all types of hinge fractures group (IHF and PHF together) than the no hinge fractures group. The IHF group had a longer time of healing than the no IHF group. In the IHF group, the mLDFA correction (p = 0.005), mLDFA correction ratio (p = 0.005), and BMI (p = 0.031) were higher than the no IHF group. The PHF was related to hinge position. The group of hinge localized proximal to the adductor tubercle (AT) had a higher rate of PHF than the group of hinge localized in the adductor tubercle (p = 0.001). The healing time in the IHF group (3.9 ± 1.4 months) was significantly longer than the healing time in the PHF group (2.7 ± 0.4 months) (p = 0.002).

Conclusion: In patients with genu valgum undergoing LOWDFO, IHF and PHF represent distinct clinical entities. IHF is associated with greater mLDFA correction, higher mLDFA correction ratios, and increased body weight. In contrast, PHF is primarily associated with hinge position, with a higher incidence observed when the hinge is located proximal to the adductor tubercle. Among the two, IHF has a more pronounced impact on delayed bone healing.

Level of evidence: Retrospective study Level IV.