Abstract
Aims: To study knee kinematics using a dynamic computer model of 2 cadaver knees obtained by bone morphing. Patellar kinematics was simultaneously investigated using transosseous pins. Method: Ligamentous injuries were done (dicision of the anterior cruciate ligament (ACL) and of the popliteus). While maintaining the foot in slight external rotation, femoral rotation was measured in relation to knee flexion in the intact and injured knee. Results: The screw home rotation between −5 and +5° was comprised between 8 and 10°. From 10° on, the lateral condyle roll-back induced 30° of femoral external rotation. Femoral rotation could be blocked by externally rotating the tibia. On the screen, the rollback of the lateral condyle and the lift-off of the medial condyle at the end of the flexion appeared clearly. The patella rotated about its longitudinal axis. Moreover, it made a lateral translation. At deep knee flexion, it contacted mainly the lateral condyle. Dicision of the ACL decreased the screw home rotation to 3° and the femoral external rotation to 20°. At 110° and over, femoral rotation ceased, while both condyles rolled anteriorly. Dicision of the popliteus reduced the lateral condyle roll-back by 50%. Conclusion: 2 types of movement can be described: the end of rotation depending of the ACL; the external rotation of the femur depending on the popliteus.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
