Tibiofemoral Relationship Research Articles

Radiographic evaluation of anterior cruciate ligament graft failure with special reference to tibial tunnel placement

Graft failure in anterior cruciate ligament (ACL) reconstruction can result from anterior placement of the tibial tunnel. Conventional radiographic evaluation of this problem does not take into account potential changes in tibio-femoral relationship caused by ACL instability. A retrospective radiographic evaluation of failed as well as successful ACL reconstructions was carried out. Both published radiographs as well as those obtained of patients treated by the authors were evaluated for tibial tunnel placement, roof impingement, and tibial position relative to the femur. In the second part of the study, the radiographs were obtained under standard conditions in both failed ACL reconstructions and normal knees. The results of both parts of the study indicate that lateral radiographs of the extended knee with ACL instability are likely to show subtle anterior tibial subluxation. The subluxation can give the impression of roof impingement on the graft. However, the majority of the failed knees had similar tibial tunnel placement compared with successful reconstructions and would appear unimpinged once corrected for subluxation. The diagnosis of graft impingement by the femoral intercondylar roof has to take into account potential tibial subluxation. Impingement as a cause graft failure may be less common than previously thought. Arthroscopy 1998 Mar;14(2):206-11

THE RADIOGRAPHIC EVALUATION OF ACL GRAFT FAILURE WITH SPECIAL REFERENCE TO TIBIAL TUNNEL PLACEMENT 16

Graft failure in anterior cruciate ligament reconstruction can be due to anterior placement of the tibial tunnel. Conventional radiographic evaluation of this problem does not take into account potential changes in tibio-femoral relationship due to the ACL instability. A retrospective radiographic evaluation of failed as well as successful ACL reconstructions was carried out. Both published radiographs as well as those obtained in patients treated by the authors were evaluated for tibial tunnel placement, roof impingement and tibial position relative to the femur. In the second part of the study the radiographs were obtained under standard conditions in both failed ACL reconstructions and normal knees. The results of both parts of the study indicate that lateral radiographs of the extended knee with ACL instability are likely to show subtle anterior tibial subluxation. The subluxation can give the impression of roof impingement on the graft. However, the majority of the failed knees had similar tibial tunnel placement compared to successful reconstructions and would appear unimpinged once corrected for subluxation. The diagnosis of graft impingement by the femoral intercondylar roof has to take into account potential tibial subluxation. Impingement as a cause of graft failure may be less common than previously thought.

Clinical Test for Anterolateral Rotary Instability of the Knee

A simplified test for anterolateral rotary subluxation of the knee is largely based on the concepts described by Galway and McIntosh although performed in a different manner. The examiner places the right hand gently on the lateral side of the knee with the thumb overlying the posterior aspect of the fibula and the index finger palpating the anterolateral aspect of the joint line to determine the the tibiofemoral relationship. The left hand embraces the lateral side of the distal end of the femur with the thumb over the posterior aspect of the lateral femoral condyle. With equal pressure on the lateral femoral condyle and fibular head the knee is pushed gently forward into flexion. When anterointernal tibial luxation is present, a reduction phenomenon is felt as the knee passes into the 25 to 40 degree flexion range. This may occur as a sudden palpable and occasionally audible repositioning which is responsible for such terminology as a "pivot shift" or "jerk sign." We have experienced many instances where the reduction phenomenon is more subtle and is determined by palpation alone. The pathologic mechanics are determined by observations at surgery in 45 patients with a positive test. This test has improved our diagnositc ability and is easly taught to those unfamiliar with knee joint disorders.