Abstract
Introduction: Varus deformity is the most common deformity in patients undergoing knee replacement. Varus correction is based on the release of the medial soft tissue of the knee. But there is no exact measure of its extent. The present study aimed to investigate radiographic parameters that can predict the need for the release of medial elements.
Materials & Methods: In this retrospective cohort study all patients who underwent primary knee replacement surgery performed in a university hospital by a single surgeon during a 2-years period were included in the study. Preoperative and post-operative knee radiographs were collected. Patients were divided into three groups based on the stage of medial release. The radiographic criteria including Mechanical Femoro-tibial angle (mFTA), Lateral distal femoral angle (LDFA), Proximal medial tibial angle (MPTA), valgus cut angle (VCA) and joint line convergence angle (JLCA) before and after surgery were compared between the groups.
Results & Discussion: A total of 115 knee radiographs, related to 103 patients were examined. There was a significant association between LDFA , MPTA , mFTA , VCA and degree of varus correction with the medial release. The degree of varus correction significantly predicts the need for a high grade of medial release (OR=1.49, P=0.01)
Conclusion: higher LDFA, mFTA, VCA, and the degree of correction of the femoral and tibial mechanical angle and lower MPTA were associated with a higher degree of medial release. And the amount of varus correction significantly predicts the need for more medial release.