Relationship between bone plug position and morphological changes of tunnel aperture in anatomic rectangular tunnel ACL reconstruction

Abstract

Purpose In animal studies after ACL reconstruction (ACL‐R) using the bone‐patellar tendon‐bone (BTB), the graft‐healing pattern was found to depend on the relationship between bone plug and the tunnel wall. This difference of graft‐healing pattern could influence the postoperative morphological changes of the tunnel. However, no study has assessed the relationship between bone plug position and the change of tunnel morphology. Therefore, the main purpose of this study was to investigate the relationship between the bone plug position within femoral or tibial tunnel and morphological changes of each tunnel aperture in ACL‐R using computed tomography. Methods Subjects were 30 consecutive patients (six females and 24 males; mean age, 20.4 ± 5.4 years) who underwent primary ACL‐R using BTB. The distance from the tunnel aperture to the tendon‐bone junction (TBJ) at 2 weeks postoperatively, and tunnel aperture enlargement and tunnel wall migration from 2 weeks to 6 months postoperatively, were evaluated. Results The distance from the femoral tunnel aperture to the TBJ in most cases was less than 2 mm, whereas the TBJ was located within the tibial tunnel. Femoral tunnel aperture was significantly enlarged (17.0 ± 11.7%) distally, and the tibial tunnel aperture was significantly enlarged (19.6 ± 12.5%) posterolaterally. Only the position at distal portion of femoral bone plug was correlated with femoral tunnel aperture enlargement (r = 0.454, p = 0.0015). Conclusion Both femoral and tibial tunnel aperture were significantly enlarged distally and posterolaterally 6 months postoperatively. Only correlation between the position at distal portion of femoral bone plug and femoral tunnel enlargement were found, suggesting the deep plug position in the tunnel is a risk factor for femoral tunnel enlargement, highlighting the importance of accurately locating the TBJ just at the femoral tunnel aperture. Another option is to deviate the harvest site in the patellar tendon to match the shape of the TBJ and the tunnel aperture. Level of evidence 4 (case series).

Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone–Patellar Tendon–Bone graft

“…studied tibial and femoral TW after anatomical rectangular tunnel ACL reconstruction using BTB grafts by CT images. 13 They showed that the femoral tunnel aperture was significantly enlarged (17.0%), and the tibial tunnel aperture was significantly enlarged (19.6%) 6 months after surgery. They also did not statistically compare femoral TW with tibial TW in the literature, although their calculations demonstrated that femoral and tibial TW were roughly equivalent.…”

“…This may mean that the influence of common femoral and tibial factors or individual factors is greater than the influence of independent factors on the femoral or tibial side, respectively, on TW. Examples of the former include age 24 or bone quality, the intra-articular environment including cytokines, 25 the initial tension on the graft tendon, 12 whereas the latter include the graft-bending angle between the femur or tibia, the windshield wiper effect, 26 and the length of the tendinous portion in the bone tunnel, 11 , 13 which depends on the position of the bone plug in the tunnel.…”

“…In addition, there are few published papers studying TW after anatomical ACL reconstruction using BTB grafts, and many of these previous studies treated femoral and tibial TW individually as separate events. 7 , 11 , 12 , 13 Therefore, the correlation between femoral and tibial TW after anatomical ACL reconstruction using BTB grafts has not been fully understood. Even among the papers that studied the relationship between PTS and TW, most examined only the effects on the tibial side of TW, 7 , 8 , 9 and the effects on the femoral side of TW have rarely been investigated.…”

ACL Graft Matching: Cadaveric Comparison of Microscopic Anatomy of Quadriceps and Patellar Tendon Grafts and the Femoral ACL Insertion Site

“…The GBA depends on femoral tunnel creation techniques, such as the transtibial, transportal and outside-in techniques. 21,41,[50][51][52][53][54] Previous studies have reported that the GBA resulting from the outside-in technique is steeper than that in the transportal technique, 21,41,50 which in turn is steeper than that in the transtibial technique. 54 Moreover, other studies have demonstrated that the shallow knee flexion angle arising during femoral tunnel creation using the modified transtibial technique could reduce GBA.…”

“…29 Although tunnel enlargement after ACL reconstruction is a concern, locating the tendon-bone junction at the femoral tunnel aperture reduced tunnel enlargement. 53 Kinugasa et al 22 reported that the BPTB autograft size after ACL reconstruction increases, while Hensler et al 17 reported that the allograft size after ACL reconstruction does not increase.…”