Soft Tissue Balancing in Total Knee Arthroplasty

Summary

Most ligament balancing problems in total knee arthroplasty can be solved by first resecting the distal femur at 5°–7° valgus and the proximal tibia perpendicular to its long axis. The next step is to remove osteophytes and release adhesions, then to insert the trial components and release tight structures. It rarely is necessary to tighten loose structures. The operative treatment principles of varus and valgus knees are the same. The most prominent surface of the joint is used as a point of reference for resection, and bony defects on the deficient side of the knee are grafted with either morselized or block autograft. Because ligament balancing in flexion is dependent on rotational alignment of the femoral component, 3°–4° of external rotation of the femoral component usually provides correct varus-valgus balance in flexion and also places the patellar groove laterally and helps to stabilize patellar tracking. Finally, the tibial component thickness is adjusted to achieve proper balance between the medial and lateral sides of the knee. Anteroposterior stability and femoral rollback are assessed, and steps are taken to achieve acceptable posterior stability.