Medial Pivot Total Knee Arthroplasty

Total knee arthroplasty (TKA) has evolved significantly, with designs like cruciate retaining (CR), posterior cruciate stabilized (PS), and ultra-congruent (UC) aimed at improving outcomes. Despite general success in pain relief and function, about 10–15% of patients remain dissatisfied. Issues such as “paradoxical motion” and the need for better replication of natural knee kinematics have driven innovations like the medial pivot TKA design. Introduced in 1994, the medial pivot TKA mimics the knee’s asymmetrical kinematics, providing a stable medial compartment and a mobile lateral compartment. This review explores TKA kinematics, comparing the medial pivot design to traditional designs, which often follow a multi-radius “J-curve” pattern, causing issues like mid-flexion instability and “paradoxical anterior motion.” The medial pivot design aims to replicate the native knee’s ball-and-socket motion in the medial compartment, enhancing stability and natural movement. Biomechanical studies have demonstrated that medial pivot knees more closely replicate knee kinematics than traditional total knee designs; however, no significant differences have been demonstrated in terms of functional or clinical outcomes. Some evidence suggests that there may be improved patient satisfaction with medial pivot designs. Technological advances like robotic TKA and gap balancing sensors may further enhance surgical precision and outcomes.