Biomechanical assessment of the knee joint during the stance phase of gait after 10 or more years of open wedge high tibial osteotomy: a comparison with short-term outcomes

BACKGROUND: External knee adduction moment indicates mechanical stress in the medial knee. Although short-term gait biomechanical outcomes after open wedge high tibial osteotomy (osteotomy) have been reported, there are no reports on long-term outcomes. We investigated knee function during the initial stance phase of gait in patients more than 10 years after osteotomy.METHODS: This study included 51 knees of 43 patients with more than 10 years after osteotomy (long-term group; age, 72.0±6.9 years) and 52 knees of 52 patients with more than 1 year after osteotomy (short-term group; age, 63.1±8.0 years) at our department. The joint angle and moment in the frontal and sagittal planes of knee were compared between the two groups using a three-dimensional motion analysis of normal gait, recorded with the VICON Motion System and infrared cameras.RESULTS: In the frontal plane, there was no significant difference between the two groups in the overall minimum knee valgus angle, maximum knee adduction moment, knee varus angle excursion, and knee adduction moment excursion. In the sagittal plane, there was a significant difference in the knee flexion angle excursion, maximum knee flexion moment, and knee flexion moment excursion (P<0.001); however, no significant difference was observed in the maximum flexion angle.CONCLUSIONS: The medial knee’s reduced mechanical stress is sustained and good knee function in the initial stance phase of gait is maintained in the long term with more than 10 years after osteotomy. Aging may lead to reduced joint angle and moment in the sagittal plane.