Kinematic Approach

This chapter presents kinematically aligned (KA) total knee arthroplasty (TKA), which sets the femoral and tibial components to resurface the patient’s pre-arthritic knee and refrains from releasing collateral ligaments and the posterior cruciate ligament (PCL). High long-term implant survival rates and superior clinical outcomes relative to mechanical aligned TKA make KA TKA an attractive alignment strategy. The surgeon first resurfaces the femur and measures each resection with a caliper to confirm the resection thickness matches the thickness of the femoral component. The tibial resection restores the patient’s pre-arthritic articular surface, verified by four caliper measurements and a rectangular extension space. Using components that restore the articular surface geometry, which include an insert with a medial 1:1 ball-in-socket and lateral flat articulation, the surgeon selects the optimal insert thickness by using an insert goniometer that measures external tibial orientation in extension and internal tibial orientation at 90° flexion. KA TKA with a medial 1:1 ball-in-socket conformity confers anterior-posterior stability, replicating anterior cruciate ligament function. Combined with an intact PCL and a flat lateral articular surface, KA TKA restores a medial pivot with close-to-native knee kinematics.