The use of functional analysis in evaluating knee kinematics.

The importance of understanding the six-degrees-of-freedom kinematics of the knee during ambulatory activities was examined in the context of the function of total knee arthroplasty. Studies of knee kinematics during walking, stair climbing, and a deep flexion squat indicate that knee kinematics is activity-dependent. A comparative study of patients and healthy subjects during stair climbing indicates the importance of maintaining the function of the posterior cruciate ligament. A second study used walking kinematics derived from patient testing as input to a wear simulator. There was increased wear relative to standard simulator input that was related to the slip velocity at the contact surface. Finally, results from a study of deep flexion indicate that substantial femoral rotation is required during deep flexion activities. The current study shows the importance of studying in vivo knee kinematics for future enhancement in the treatment of the arthritic knee.