Reduced lateral hinge stress and fracture risk in double-hinge medial open-wedge high tibial osteotomy: A finite element study.

Abstract

<h4>Objectives</h4>This study aims to describe the double-hinge medial open wedge high tibial osteotomy (DH-MOWHTO) with two lateral hinges and to investigate its feasibility and its utility in prevention of lateral hinge fractures (LHFs) using a finite element analysis (FEA) model.<h4>Materials and methods</h4>Three osteotomies were modeled. Model 1 (DH-MOWHTO) involved two monoplanar osteotomies from the same starting point, while Models 2 and 3 were standard monoplanar osteotomies using one osteotomy line from Model 1. They were compared in terms of maximum von-Mises stress value (MPa) in the hinges at 10° correction angle, gap distance at 10° correction angle (mm), force required to achieve a 10° correction angle (N), and total surface area (mm² ) of osteotomy surfaces contacting the saw.<h4>Results</h4>In DH-MOWHTO, the maximum anterior hinge stress at 10º correction angle was reduced by 28.1 to 39.6% and the maximum posterior hinge stress was reduced by 19.2 to 60.1% compared to single monoplanar osteotomies. The average stress reduction in the hinges was 36%. The force required for a 10° correction was approximately 78 N, 114 N and 85 N for Models 1, 2 and 3, respectively. The model with two monoplanar osteotomies had approximately 1.8 and 2 times more osteotomy surface area than Models 2 and 3, respectively.<h4>Conclusion</h4>In this FEA study, two lateral hinges can be created in MOWHTO and lower hinge stresses can be obtained by applying lower forces with this osteotomy. In the light of these findings, DH-MOWHTO may be a novel osteotomy technique to avoid LHF.