Chandana R. KarunathilakaGeneral Sir John Kotelawala Defence University, Sri Lanka
Title: Balancing the Valgus knee and avoiding pitfalls during total knee arthroplasty
Valgus deformity of the knee is mainly bony and soft tissue related. Bony Factors include the distal femur lateral condyle distortion with hypoplasia, a defective lateral tibial plateau with hypoplasia and patella malalignment. It results in soft tissue contracture in the lateral aspect of the knee and stretching of soft tissues on the medial side. Prior to surgery clinical and radiological assessment of deformity in standing and supine, varus and valgus deformity, and presence of posterior and lateral osteophytes are important. The femoral epicondylar line is used as the reference point with an intramedullary jig. It is advisable to take in 3° of valgus in relation to the anatomical axis when performing the distal femoral cut. Femoral resection should be no more than 10 mm in the medial condyle (usually 7–8 mm). The Tibial bone cut should be 90° to its longitudinal axis and allow 3–5°posterior slope using an extramedullary rod. The depth of the resection should be limited to 6–8 mm in the medial compartment. The soft tissue release and bone cuts aim to achieve a rectangular extension gap. Minimal exposure on the medial side, removal of posterior osteophytes, and posterior lateral release of the joint capsule along the margin of the tibial plateau would help to achieve a reasonable extension gap. For further advanced release pie crusting of popliteus, pie crusting of lateral collateral ligament, and pie crusting of the IT band can be considered. External rotation of the femoral component is important in preventing patellar femoral maltracking. During the trial, varus-valgus stability is assessed in extension, mid-flexion, and patella tracking with the trial implant. Post-operative complications include tibiofemoral instability, residual valgus deformity, restricted range of motion, wound dehiscence, residual valgus deformity, and peroneal Nerve Palsy.
Chandana Karunathilaka is a senior lecturer in surgery at the Faculty of Medicine, Sir John Kothelawala Defence University- Sri Lanka. He is qualified with MBBS, MS(SL), MRCS(Eng), MCh (Trauma & Orthopaedic)-Edinburgh. He works as a Consultant Orthopaedic & Trauma Surgeon at University Hospital- Sir John Kothelawala Defence University Sri Lanka.