Soft Tissue Release for Varus Knees during Posterior Stabilized Total Knee Arthroplasty: A New Algorithm

Abstract

Introduction: Total Knee Replacement (TKA) surgeries are frequently performed surgeries used to treat knee osteoarthritis. Several methods of medial soft tissue balancing in the varus knee during total knee replacement surgeries have been reported. Traditionally, they included releasing the superficial Medial Collateral Ligament (sMCL) in severe varus cases by several methods. However, this release can create instability in the knee. The aim of this study was to create an algorithm for soft tissue release in varus osteoarthritic knees and to evaluate its efficacy in achieving intraoperative gap balancing without releasing the superficial MCL. Materials and Methods: One hundred and five varus osteoarthritic knees who received primary posterior stabilized total knee arthroplasties between October 2015 and January 2016 were included in this study. Varus deformities ranged between 10 to 40 degrees. Sequential balancing was done into 5 steps: step 1 – releasing of deep MCL, step 2 – excision of osteophytes, step 3 – excision of scarred tissue in the posteromedial corner, step 4 – excision of the posteromedial capsule and step 5 – release of semimembranosus. The V-STAT® Variable Soft Tissue Alignment Tensor was used to ensure a balanced medial and lateral gap following each step. Once the gaps were balanced, no further soft tissue release were carried out. Results: All knees were balanced without releasing the superficial MCL ligament. The maximum release step necessary was: step 1 (0 cases), step 2 (31 cases), step 3 (35 cases), step 4 (25 cases) and step 5 (14 cases). Conclusion: Superficial medial collateral ligament should not be released during intraoperative varus knees soft tissue balancing in posterior stabilized total knee arthroplasties. Preserving the superficial MCL is beneficial in maintaining implant stability without any increase in the constraint level of the implant even in cases with severe deformity.