Utilizing a new testing method, we are reporting for the first time on the ranked order of importance of each ligament and capsular structure in resisting the clinical anterior and posterior drawer tests. The ranked importance is based on the force provided by each ligament in resisting the drawer tests. Tests were conducted with the knee at 90 and 30 degrees of flexion up to five millimeters of anterior and posterior drawer in the intact knee. A second series of tests was also performed at larger drawer displacements to determine the back-up restraints to drawer motions when the cruciate ligaments have been cut. In anterior drawer the anterior cruciate ligament is the primary restraint. It provides an average of 86 per cent of the total resisting force. All other ligaments and capsular structures provide the remaining secondary restraint, each typically less than 3 per cent. For straight posterior drawer, the posterior cruciate ligament provides a mean of 95 per cent of the total restraining force. After loss of the posterior cruciate ligament, the secondary restraints to the posterior drawer test are the posterior lateral capsule and popliteus complex combined (58 per cent), the medial collateral ligament (16 per cent), and to a lesser extent many other structures. The anterior cruciate ligament did not resist posterior drawer, nor did the posterior cruciate ligament resist anterior drawer. A false-positive anterior drawer test after rupture of the posterior cruciate ligament occurs due to a posterior shift in the starting position of the tibia.
Copyright remains with the authors and publisher.
Utilizing a new testing method, we are reporting for the first time on the ranked order of importance of each ligament and capsular structure in resisting the clinical anterior and posterior drawer tests. The ranked importance is based on the force provided by each ligament in resisting the drawer tests. Tests were conducted with the knee at 90 and 30 degrees of flexion up to five millimeters of anterior and posterior drawer in the intact knee. A second series of tests was also performed at larger drawer displacements to determine the back-up restraints to drawer motions when the cruciate ligaments have been cut. In anterior drawer the anterior cruciate ligament is the primary restraint. It provides an average of 86 per cent of the total resisting force. All other ligaments and capsular structures provide the remaining secondary restraint, each typically less than 3 per cent. For straight posterior drawer, the posterior cruciate ligament provides a mean of 95 per cent of the total restraining force. After loss of the posterior cruciate ligament, the secondary restraints to the posterior drawer test are the posterior lateral capsule and popliteus complex combined (58 per cent), the medial collateral ligament (16 per cent), and to a lesser extent many other structures. The anterior cruciate ligament did not resist posterior drawer, nor did the posterior cruciate ligament resist anterior drawer. A false-positive anterior drawer test after rupture of the posterior cruciate ligament occurs due to a posterior shift in the starting position of the tibia.
Copyright remains with the authors and publisher.