Effects of the tibial tunnel position on knee joint stability and meniscal contact pressure after double-bundle anterior cruciate ligament reconstruction

To investigate the effect of the tibial tunnel position on knee stability and the maximum contact area and peak contact pressure on the menisci after double-bundle anterior cruciate ligament (ACL) reconstruction. Ten human knee specimens (mean age: 74.1 ± 15.8 years) were used in this study. The anterior tibial loading test was conducted using a material testing machine at 30°, 60°, and 90° of knee flexion, with the anterior tibial translation (ATT) and the maximum contact area and peak contact pressure on the menisci measured. Outcome measures were compared between the following groups: 1) intact ACL (intact group); 2) anatomical tibial tunnel position (anatomical group) and 3) posterior tibial tunnel position (posterior group) with double-bundle reconstruction, and 4) ACL-deficient (deficient group). In response to a 100 N anterior tibial load, the ATT was greater for the posterior and ACL-deficient groups compared to that in the intact group. The normalized maximum contact area of the medial meniscus significantly decreased for the posterior group compared to that in the intact group. The normalized peak contact pressure on the medial meniscus increased in all groups compared to that in the intact group, but with no between-group differences in pressure applied to the lateral meniscus. ATT and contact pressure on the medial meniscus increased, concomitant with a decrease in contact area of the medial meniscus, as the position of the tibial tunnel position moved towards a posterior position.