Severe Instability

In primary total knee arthroplasty (TKA), instability can be addressed in most cases with cruciate-retaining (CR) and posterior-stabilized (PS) standard implants by achieving good alignment and proper soft tissue balancing. However, a more rigid restraining implant may be necessary in cases of severe instability or hyperextension with significant collateral ligament dysfunction or when soft tissue balance cannot be properly achieved intraoperatively.