Functional outcome after total knee arthroplasty is determined by strength, stability and range of motion. Flexion in the replaced knee is suboptimal for many patients and kinematics after total knee arthroplasty is abnormal. The relation between kinematics of the replaced knee and postoperative flexion is analyzed and compared to normal knee kinematics. Specific characteristics that relate to better flexion are defined: posterior condylar offset, femoral roll-back and femoral external rotation. The rationale for a guided motion knee arthroplasty is developed and positioned within the current state of the art knowledge on total knee arthroplasty.
Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.