Abstract
Anterior cruciate ligament (ACL) of four major knee ligaments is most crucial ligament to maintain normal knee kinematics. It is well know that ACL dysfunction causes secondary osteoarthritis of the knee. The influence of age on the biomechanical properties of the ACL was examined. The structural properties of 27 pairs of human cadaver knees without OA were evaluated. Specimens were equally divided into three groups of nine pairs each based on age: younger (22 to 35 years), middle (40 to 50 years), and older (60 to 97 years). Tensile tests of the femur-ACL-tibia complex were performed at 30 degrees of knee flexion with the ACL aligned vertically along the direction of applied tensile load. Structural properties of the femur-ACL-tibia complex, as represented by the linear stiffness, ultimate load, and energy absorbed, were found to decrease significantly with specimen age.
On the other hand, little has been written about the arthritic ACL. This study was designed to evaluate the relationship among ROM, cross sections of the intercondylar notch and the macroscopic condition of ACL degeneration. Fifty osteoarthritic patients who underwent TKA as a result of severe osteoarthritis were randomly selected. Occupation rate of the osteophytes to the notch width were measured at the anterior 1/3, middle 1/3, and posterior 1/3 notche images obtained from preoperative tunnel view. ROM was measured preoperatively and under anesthesia. Macroscopic conditions of the ACL and PCL were classified into four types of Normal, Frayed, Partial rupture, and Absent.
The macroscopic ACL conditions were Normal: 12 cases, Frayed: 15 cases, Partial rupture: 14 cases, and Absent: 9 cases. The macroscopic PCL conditions were Normal: 34 cases, Frayed: 9 cases, Partial rupture: 7 cases, and Absent: 0 case. Occupation rate of the osteophytes to the notch correlated to the preoperative varus deformity (p < 0.05). In terms of ACL, the occupation rate of the osteophytes to the notch were 22.9%, 28.8%, 46.0%, and 81.8% in Normal, Frayed, partial ruptured, and Absent, respectively. The patients with more than 40% occupation rate and less than 110 degree of knee flexion angle showed either partial rupture or absent of the ACL during the surgery. Those results correlated with the degree of OA deterioration. We conclude that occupation rate of the osteophytes to the notch poor preoperative ROM is a good predictor of evaluating the ACL degeneration in osteoarthritic knee. We also conclude that ACL dysfunction due to joint space narrowing accelerates the advancement of the knee OA.
