Understanding tibio-femoral motion.

There has been little advance in understanding of tibio-femoral motion for a few decades. It has been held that during knee flexion the femur bodily rolls-back on the tibia, and furthermore that his phenomenon is produced by tension in the ('four-bar' linkage) cruciate ligaments. These concepts are flawed. Previous studies on joint motion have relied on techniques with various limitations causing inaccuracy and tendency to misinterpretation. Employing an 'interventional' MRI scanner to image subjects standing and undertaking a squat the living knee can be image in three dimensions under weight-bearing conditions. This review article summarizes the findings of a number of studies from the unit employing this technique and other collaborators to define normal tibio-femoral kinematics. These findings represent a fundamental alteration in understanding in this field.