The correction of Thai varus knee by high tibial osteotomy with Fujisawa’s point using finite element analysis

Abstract

The patients of congenital varus knees may suffer from osteoarthritis symptoms which need corrective surgery on the deformed knees. High tibial osteotomy (HTO) with Fujisawa’s point is a complicated but effective treatment where the surgeon realigns the deformed varus knees to the normal knee position to preserve the ligaments, tendons and meniscus. The purpose of research was to evaluate the distributed stress and strain on the eight lower extremity models as follows: Thai varus knee, HTO corrected using Fujisawa’s point varied in 5 different lateral position, 30% lateral point of load-bearing axis, 33% lateral point of load-bearing axis, 35% lateral point of load-bearing axis, 38% lateral point of load-bearing axis and 40% lateral point of load-bearing axis, HTO corrected at the midpoint of proximal tibia, and knee joint inserted with total knee prosthesis. These eight lower extremity models were evaluated under daily activities using finite element method. The stress and strain distribution of the lower extremity using HTO with Fujisawa’s point were analyzed to indicate the most appropriate position to ensure that the stress and strain distribution does not exceed its maximum capacity; the femur would not break. HTO corrected using Fujisawa’s point of 40% lateral point of load-bearing axis, compared to other Fujisawa’s models, resulted in the maximum equivalent total strain closest to that of normal knee. However, knee joint inserted with total knee prosthesis resulted in strain distribution most similar to that of normal knee.