Pre-Clinical Evaluation of Total Knee Designs for Normal Function

Although Total Knee Replacement (TKR) is successful both in function and durability, there is evidence that the kinematics are abnormal, suggesting that function can be further improved, especially in patients with the capability of returning to an active lifestyle. The goal of this study was to formulate a testing method which would predict the performance of a TKR by using the mechanical characteristics of the anatomic knee as a benchmark. It is proposed that a ‘holistic testing method’ should consist of a determination of the neutral path of motion during a full flexion range, together with the AP and rotational laxity about the neutral path. This test regimen would represent the forces and torques experienced in a range of everyday activities. The proposed testing method is evaluated using a special test rig to compare the kinematics of different TKR designs, with anatomic knee specimens.