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Lateral intra-articular varus osteotomy is an L-shaped osteotomy of the lateral tibial condyle to correct mild knee valgus and lateral plateau malunion of the proximal tibia. In order to minimize injury, it was modified to preserve the posterolateral cortex and the upper tibiofibular joint. The aim of this study was to evaluate the stability of modified lateral intra-articular varus osteotomy by comparing the biomechanical strength with lateral intra-articular varus osteotomy. Twenty-four synthetic tibia models were divided into 2 groups based on osteotomy type. Each model was then fixed with 2 commonly used plate systems. Biomechanical tests were conducted to measure parameters including construct stiffness, wedge displacement, and the number of failed specimens, and the results were compared among different groups. No significant difference was found in construct stiffness among all groups (P > 0.05). There was also no significant difference in wedge displacement among all groups (P > 0.05). When an axial load of 1500 N was applied, the number of failed specimens showed no significant difference among all groups (P > 0.05). The main failure pattern was additional fracture lines on the lateral tibial plateau. The findings indicate that there was no significant difference in stability between the 2 groups under the tested loading conditions. Furthermore, it appears that preserving the posterolateral cortex may have no impact on biomechanical stability. • Biomechanical study of lateral high tibia osteotomy with synthetic bones. • Modified lateral intra-articular varus osteotomy construct is stable. • Modified osteotomy has comparable reliability compared to traditional osteotomy. [ABSTRACT FROM AUTHOR]

Lateral hinge fractures are common complications in the medial opening wedge high tibial osteotomy for treatment of knee osteoarthritis. The rehabilitation protocols are decided depending on the remaining stability following these fractures. This study aimed to evaluate the biomechanical properties of different types of lateral hinge fractures in medial opening wedge high tibial osteotomy. Twenty synthetic tibia models were used as test samples. A 10-mm bone wedge was removed from the medial side of the proximal tibias to create the bone defect. The samples were then divided into 4 groups: (1) intact lateral hinge; (2) Takeuchi type I fractures; (3) type II fractures; and (4) type III fractures. After fixation with a locking plate, the stability parameters including construct stiffness, wedge displacement, and construct strength were tested under compressive forces and compared among the 4 groups. No statistical difference was found in the construct stiffness among the 4 groups (P = 0.78). The type III fractures had the largest wedge displacement compared with the other 3 groups. The failure loads on average were significantly reduced in the type III fractures compared with those with intact hinge (P < 0.01) and in type I fractures (P = 0.04). No statistical difference was observed between the type I fractures and the intact hinge in terms of wedge displacement or failure loads. The type III fractures were the most unstable and patients with these fractures should be managed cautiously. Delayed weightbearing and/or additional fixation should be considered. • The first biomechanical study of lateral hinge fractures in high tibial osteotomy. • Takeuchi Type I fractures are the most stable lateral hinge fractures. • Takeuchi Type III fractures are the least stable lateral hinge fractures. • Additional fixation intraoperatively should be considered in type III fractures. • Delayed weightbearing postoperatively is recommended for type III fractures. [ABSTRACT FROM AUTHOR]