The effect of intra-operative knee flexion angle on determination of graft location in the anatomic double-bundle anterior cruciate ligament reconstruction

Background: Graft impingement is one of the main concerns in double-bundle anterior cruciate ligament reconstruction (DB-ACLR). Impingement between the anteromedial (AM) and posterolateral (PL) bundles has been postulated to cause graft deterioration or rerupture, but this has not been thoroughly investigated, and the interbundle impingement pressure (IIP) has not been well researched. Purpose: To determine the IIP between the AM and PL bundles in the native anterior cruciate ligament (ACL) and in DB-ACLR with individualized and nonindividualized double-tunnel placement. Study Design: Controlled laboratory study. Methods: A total of 30 fresh-frozen, nonpaired, human cadaveric knees were randomly divided into 3 groups of 10 knees: native intact ACL (NI group), DB-ACLR tunnel placement using the preserved remnant procedure (individualized reconstruction) (PR group), and DB-ACLR tunnel placement using the bony landmark procedure (nonindividualized reconstruction) (BL group). Pressure sensors were inserted between the AM and PL bundles. The knee was moved passively from full extension to full flexion, and the IIP between the 2 ACL bundles was measured every 15°. Similarly, the impingement pressure was measured between the ACL and intercondylar roof and between the ACL and posterior cruciate ligament (PCL). Results: No significant differences were found in the maximum, mean, or minimum ACL-roof and ACL-PCL impingement pressures among the 3 groups. The IIP significantly increased when the knee joint was flexed >120° in all 3 groups ( P < .001). Compared with the other 2 groups, the BL group had significantly higher maximum and mean IIP throughout the range of knee movement ( P < .001) and from maximum extension to 120° of flexion ( P < .001). The BL group also had significantly higher minimum IIP than the other 2 groups when knee flexion was >120° ( P < .001). No significant differences were seen in maximum, minimum, or mean IIP between the NI and PR groups. Conclusion: The PR procedure (individualized DB-ACLR) was more consistent with the interbundle biomechanical conditions of the native ACL, whereas the BL procedure (nonindividualized DB-ACLR) had higher maximum and mean IIP. The IIP was higher than the ACL–intercondylar roof or ACL-PCL pressures, and it increased significantly when knee flexion was >120°. Clinical Relevance: These data suggest that surgeons can perform individualized DB-ACLR using preserved remnants for tunnel placement as impingement-free DB-ACLR.

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Determination of a Safe Range of Knee Flexion Angles for Fixation of the Grafts in Double-Bundle Anterior Cruciate Ligament Reconstruction

The American Journal of Sports Medicine ◽

10.1177/0363546507300822 ◽

2007 ◽

Vol 35 (9) ◽

pp. 1513-1520 ◽

Cited By ~ 35

Author(s):

Fabio Vercillo ◽

Savio L-Y. Woo ◽

Sabrina Y. Noorani ◽

Özgür Dede

Keyword(s):

Anterior Cruciate Ligament ◽

Anterior Cruciate Ligament Reconstruction ◽

Knee Flexion ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Double Bundle ◽

Cruciate Ligament Reconstruction ◽

Fixation Protocol ◽

Anterior Cruciate

Background For anterior cruciate ligament reconstruction with a double-bundle procedure, one of the major concerns is to not predispose either one of the grafts to risk of failure by overloading. Hypothesis Knee flexion angles between 15° and 45° for anteromedial graft fixation and 15° for posterolateral graft fixation are safe for both grafts in double-bundle anterior cruciate ligament reconstruction. Study Design Controlled laboratory study. Methods Nine human cadaveric knees were tested. The double-bundle anterior cruciate ligament reconstruction was conducted with both grafts fixed at 15° of knee flexion (fixation protocol 15/15) and again with the anteromedial and posterolateral grafts fixed at 45° and 15° of knee flexion (fixation protocol 45/15). For both fixation protocols, the knee kinematics and the in situ forces of the reconstructed anterior cruciate ligament and its individual grafts were measured and collected under an anterior tibial load of 134 N and combined rotatory loads of 10 N·m of valgus and 5 N·m of internal tibial torque. The data from both fixation protocols were compared with those of an intact knee. Results In response to the 2 external loading conditions, both fixation protocols (15/15 and 45/15) could restore the knee kinematics to within 2 mm of the intact knee (although statistically significant differences were found between fixation protocol 15/15 and the intact knee) and the overall in situ forces in the grafts similar to the intact anterior cruciate ligament. In response to the 134-N anterior tibial load, the in situ forces in the anteromedial graft for both fixation protocols did not exceed those of the intact anteromedial bundle. But at 30° and 45° of knee flexion, the in situ forces for fixation protocol 15/15 were 20.7% and 22.1% lower, respectively, when compared with the intact anteromedial bundle. Under combined rotatory loads, the anteromedial graft for fixation protocol 15/15 had in situ forces that were 45% lower than the intact anteromedial bundle at 30° of knee flexion. The in situ force in the posterolateral graft for both fixation protocols did not exceed those of the intact posterolateral bundle, nor were they significantly different from the intact posterolateral bundle at any of the flexion angles tested. Conclusion Both fixation protocols restored knee kinematics without predisposing either graft to failure. Therefore, knee flexion angles between 15° and 45° for graft fixation were found to be safe for the anteromedial graft, while 15° of knee flexion was safe for the posterolateral graft. Clinical Relevance A range of knee flexion angles that is safe for the fixation of both grafts in double-bundle anterior cruciate ligament reconstruction was determined.

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