Dealing with severe varus deformities in TKA

Ashok Rajgopal
Varus knee deformity is the most commonly encountered frontal plane deformity during TKA. Severe varus deformity is usually defined as an angular deformity of >200 and is frequently associated with severe restriction of pre-operative ROM and usually a flexion contracture. The deformity can be intra- or extra-articular or both. The aim is to achieve a neutral alignment, adequate ligamentous balance, and correction of bony defects. Extra-articular deformities may need osteotomy and correction either before or during the TKA procedure. Progressive sequential release of the medial soft tissue involves elevation of the deep and proximal part of superficial MCL, semi-membranosus insertion, postero-medial capsule, release of anterior (in flexion contracture) or posterior (in extension contracture) of superficial MCL, and extreme cases may require MCL pie-crusting or MCL advancement (eg. medial epicondylar osteotomy) and sometimes reconstruction of the MCL. Bony defects necessitate the use of bone grafts (auto/allografts), metallic wedge augments, and stem extensions. Greater degrees of constraints may be necessary including constrained condylar prosthesis and hinged knees. The final outcome depends on the degree of initial deformity, pre-operative ROM, residual post-operative flexion contracture, patient characteristics and surgical technique. The results of TKA in severe varus knees is extremely satisfying with results approaching, though lower than when TKA is done for knees with minor deformities.