Purpose
Contralateral hinge fracture is one of the most common complications of medial-opening wedge high tibial osteotomy (HTO) and has been associated with non-union, varus recurrence, and revision surgery. However, this complication has never been investigated after closing-wedge HTO (CW-HTO). The aim of the study was to evaluate the incidence and classify medial cortical hinge fractures after CW-HTO and to identify patient-related and surgical-related risk factors for the development of medial hinge fractures (MHF).
Methods
Consecutive patients who underwent CW-HTO for varus malalignment performed by a single senior surgeon from 2007 to 2020 were screened for eligibility. Demographical, radiological and surgical data were retrieved from the medical charts. The incidence and type of MHF, the presence of medio-lateral dislocation (>2mm) or hinge fracture gap (>3mm) were evaluated on X-rays. .
To determine the risk of MHF, mediolateral dislocation and fracture gap, a series of univariate logistic regression were performed. The dependent variable was defined as the incidence of hinge fracture, mediolateral dislocation, or gap while the independent variables were age, sex, BMI, smoking, other previous surgeries, preop. HKA, and additional eight measurement related to the osteotomy cut.
Results
A total of 137 knees, with a mean age of 43.7 ± 10.5 years were included in the present study. The incidence MHF fractures was 57% and five distinct types of fractures were identified. The most common fracture type was the linear (31%), followed by distal (9%) and proximal (8%) extension of the fracture related to the osteotomy. A “third fragment” fracture type was identified in 7% of the patients and an intra-articular extension in 2%. Both the patients from the latter groups required intraoperative fixation with additional screws.
According to the univariate analyses: female sex, Hto-Medial Plateau Distance, Hto Ml Width, and Hto / Tibial Ml Width were significantly associated with the “fracture group” and were included in the multivariate analysis. For gap (<3mm), the independent variables were Hinge Ml Width, Hto Ml Width, and Hto / Tibial Ml Width. No significant variables were found for mediolateral dislocation.
The multiple regression analysis showed that Hto-Medial Plateau Distance and Hto Ml Width were significantly associated with hinge fracture, while for the dependent variable gap, no variables were found to be significant.
Conclusion
Medial hinge fracture (MHF) is a common complication after closing wedge high tibial osteotomy (CW-HTO), and all the risk factors appear to be related to the osteotomy line. An increased HTO-Medial Plateau distance (i.e., the height of the osteotomy cut relative to the joint line) and a reduced HTO-Ml width of the cut (i.e., increased depth of the cut) were significantly associated with MHF in the multivariate analysis. These two surgical parameters are clinically significant as they are modifiable. The findings of this study offer valuable insights for surgeons, enabling them to better define the height and depth of the osteotomy cut in order to mitigate the risk of MHF.