Abstract
Few studies exist describing unicompartmental osteoarthritic knee kinematics. Moreover, the role of the anterior cruciate ligament (ACL) in the determination of knee kinematics has not been fully described. The objective of the current study was to analyze the in vivo kinematics of knees with medial osteoarthritis (OA) and intact ACL during closed and open chained motion. Eight patients scheduled for UKA diagnosed with primary medial OA underwent knee CT-scans and video-fluoroscopy. Fluoroscopic analysis included stair climbing, chair rising and leg extension. Three-dimensional bone positions were obtained from each image by iterative procedures using a CAD-model-based shape-matching technique. Patterns of axial rotation and anterior-posterior (AP) motion of the medial and lateral femoral condyle were obtained with specific software. The femur reported an overall external rotation relative to the tibia from extension to flexion in all tasks. Average AP translation of the medial femoral condyle were smaller in open-chained tasks than in weight-bearing conditions. Average AP motion of the lateral femoral condyle reported an overall posterior translation with knee flexion. The absent natural "screw-home" mechanism and the lack of medial condyle posterior translation was explained by bone-cartilage defects and meniscal degeneration. Relevant findings were the kinematic pattern differences between weight-bearing and open chained activities, suggesting that in biphasic muscle contraction and unloaded conditions, the function of the cruciate ligaments was not physiological. The kinematics of knees with medial OA and intact ACL differed from healthy knees.
Highlights
The evaluation of in vivo knee kinematics is important in order to understand the effects of joint injury, diseases and in order to improve the outcome of surgical procedures.Video-fluoroscopic analysis has been used for 20 years to determine knee motion from fluoroscopic image sequences [1,2], both for patients operated with total knee arthroplasty (TKA) [3,4] and more recently for motion measurements in normal or osteoarthritic joints.Healthy knee kinematics has been assessed with videofluoroscopic analyses to understand the deviations of the kinematics after surgical treatment [5]
Similar absolute values of femoral axial rotation were observed in chair rising and stair climbing from 10° to 70° of knee flexion
This finding has already been noted by Matsui et al, who evaluated the femoro-tibial rotation using CT and reported that the femur tended to locate in a relative internal rotation position in knees with severe OA compared to normal joints [11], and by Hamai et al in their video-fluoroscopic analysis of the kinematics of the osteoarthritic knee [6]
Summary
The evaluation of in vivo knee kinematics is important in order to understand the effects of joint injury, diseases and in order to improve the outcome of surgical procedures.Video-fluoroscopic analysis has been used for 20 years to determine knee motion from fluoroscopic image sequences [1,2], both for patients operated with total knee arthroplasty (TKA) [3,4] and more recently for motion measurements in normal or osteoarthritic joints.Healthy knee kinematics has been assessed with videofluoroscopic analyses to understand the deviations of the kinematics after surgical treatment [5]. Moro-oka et al described healthy knee kinematics during the activities of squatting, stair climbing and kneeling and reported an overall femoral external rotation relative to the tibia with flexion. Constant rotation and posterior translation of both condyles from 20° to 80° (stair climbing) and an increasing femoral external rotation from 80° to 150° flexion (kneeling) resulted predominantly from posterior lateral translation, essentially pivoting about the medial compartment. In this range of flexion, medial AP tibio-femoral translation was reduced, determining a medial pivot point kinematics [5]
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