Tibiofemoral contact points relative to flexion angle measured with MRI

Objective. To determine whether knee flexion influenced bony contact movements during flexion. Design. Accurate three-dimensional (3D) measurements of tibiofemoral bony contact points in vivo was performed using magnetic resonance imaging technology at 0°, 30° and 60° of flexion. Background. Magnetic resonance imaging is an accurate non-invasive tool for visualizing muscles, tendons, and bone, and provides precise 3D co-ordinates. Methods. Magnetic resonance imaging recordings were made from the right knee of 16 subjects with no history of knee dysfunction at 0°, 30° and 60° of flexion. Joint contact movements were reported as changes of the contact pointʹs position on the medial and lateral tibial condyle with respect to a fixed reference point for each flexion angle. Results. The dominant motion of the centroid of the contact area was posterior with a concomitant inferior and lateral displacement when flexing from 0–30°. Increased flexion to 60° the contact points moved slightly anterior, superior and continued laterally. Comparing movements between the medial and lateral compartments, larger displacement magnitudes were observed laterally. Additionally, tibial rotations of 3–5° were noted relative to the femur. Conclusion. Based on magnetic resonance imaging co-ordinates and the rotated anatomical reference frame, the geometric equations to derive the contact point between the tibiofemoral articulating surfaces is a viable means to investigate tibiofemoral bony contact movement.