Change in leg length after open-wedge high tibial osteotomy can be predicted from the opening width: A three-dimensional analysis

Abstract

BackgroundThe purpose of this study was to evaluate true change in leg length after open-wedge high tibial osteotomy (OWHTO) using three-dimensional (3D) assessments, examine the factors that influence leg lengthening and verify their validity in clinical practice. MethodsStudy 1: a retrospective case series simulation study, included 46 patients (55 knees) that underwent knee arthroplasty or HTO. OWHTO was simulated from preoperative computed tomography using 3D preoperative planning software. Uni- and multivariate regression analyses were conducted to identify predictors related to change in leg length. Study 2: a retrospective case series study, included 53 patients (55 knees) that underwent OWHTO in another institution. Change in leg length was measured preoperatively and 1 year postoperatively and was compared with the predicted change in leg length calculated using the formula obtained from Study 1. ResultsStudy 1: the true change in leg length significantly increased and showed a strong correlation with the opening width. The change in leg length was predicted using the formula “change in leg length = opening width × 0.75–1.5.” Study 2: the predicted change in leg length showed no significant difference from the change in leg length 1 year postoperatively and a strong correlation with the measured change. ConclusionsThe true change in leg length after OWHTO was predicted using the formula obtained from the 3D model. Predicting the change in leg length preoperatively can be a basis to consider other HTOs.