Evaluation of the relationship of tibiofemoralkinematics before and after total knee replacement in an in vitro model of cranial cruciate deficiency in the dog

OBJECTIVE: To investigate the relationship between tibiofemoral kinematics before and after total knee replacement (TKR) in vitro. ANIMALS: Eight canine hemipelves. METHODS: A modified Oxford Knee Rig was used to place cadaveric limbs through a range of passive motion allowing the kinematics of the stifle to be evaluated. Four measurements were performed: a control stage, followed by a cranial cruciate transection stage, then following TKR with the musculature intact stage, and finally TKR with removal of limb musculature stage. Joint angles and translations of the femur relative to the tibia, including flexion-extension versus adduction-abduction, flexion-extension versus internal-external rotation, as well as flexion-extension versus each translation (cranial-caudal and lateral-medial) were calculated. RESULTS: Significant differences were identified in kinematic data from limbs following TKR implantation as compared to the unaltered stifle. The TKR resulted in significant decreases in external rotation of the stifle during flexion-extension compared to the limb prior to any intervention, as well as increasing the abduction. The TKR significantly increased the caudal translation of the femur relative to the tibia compared to the unaltered limb. When compared with the cranial cruciate ligament-transection stage, TKR significantly decreased the ratio of the external rotation to flexion. DISCUSSION: All three test periods showed significant differences from the unaltered stifle. The TKR did not completely restore the normal kinematics of the stifle