A new classification for the valgus knee related to total knee arthroplasty and implant selection

Background: We propose a novel classification for valgus knee deformity related to total knee arthroplasty, developed by evaluation of conventional and stress radiographs, clinical examination and a retrospective level 2 analysis of the implants selected for the treatment of valgus knees in a single institution.

Methods: This study includes the analysis of 335 total knee arthroplasties evaluated with AP standing and stress radiographs and clinical examination. The anatomical knee axis and the radiographs were measured by 2 different knee surgeons to determine the interobserver reliability.

Results: This new classification of valgus knees, focused on joint wear, stability and ligament sufficiency was developed in order to understand and define the knee types and relate them to the implant that should be utilized.

Conclusion: This new classification allows for better understanding of valgus knee deformities, defining ligament status and valgus types, and it seems to be a comprehensive tool for preoperative planning and the choice of prosthetic constraint. Constrained implants should be used in cases with coronal instability with attenuated medial collateral ligament. Rotating hinges must be reserved for medial collateral ligament incompetence, associated significant recurvatum, multidirectional instability and/or severe muscular deficiency.

Keywords

severe valgus knee, ligament incompetence, attenuated MCL