Background

Recent biologic and biomechanical adjuncts including the concept of suture tape augmentation have led to a renewed interest in primary repair of the anterior cruciate ligament (ACL). The purpose was to compare knee kinematics in a cadaveric model of ACL repair using an adjustable-loop femoral cortical suspensory (AL-CSF) or independent bundle suture anchor fixation (IB-SAF) with suture tape augmentation to a bone-patellar tendon-bone (BPTB) ACL reconstruction. The authors hypothesized that (1) each technique would restore native anterior tibial translation (ATT) and internal tibial rotation (ITR) and that (2) there would be no significant differences in knee joint kinematics between the three techniques utilized.

Methods

Twenty-seven cadaveric knees (mean age: 52.5 ± 11.7 years) were randomly assigned to one of three surgical techniques: (1) ACL repair using the AL-CSF technique with suture tape augmentation, (2) ACL repair using the IB-SAF technique with suture tape augmentation, (3) ACL reconstruction using a BPTB autograft. Each specimen underwent three conditions according to the state of the ACL (native, proximal transection, repair/reconstruction) with each condition being tested at four different angles of knee flexion (0°, 30°, 60°, 90°). Anterior tibial translation (ATT) and internal tibial rotation (ITR) were evaluated using 3-dimensional motion tracking software. Assuming a standard deviation of 1.25mm in ATT, a sample size of 8 specimens per group would provide 80% power to detect a difference of 2.0 mm in ATT at an alpha level of 0.05.

Results

ACL transection resulted in a significant increase in ATT and ITR at 0°, 30°, 60°, and 90° of knee flexion when compared to the native state (P<0.001, respectively). ACL repair with the AL-CSF or IB-SAF technique as well as BPTB reconstruction restored native ATT and ITR at all tested angles of knee flexion, while showing significantly less ATT at 0°, 30°, 60°, and 90° as well as significantly less ITR at 30°, 60°, and 90° of knee flexion when compared to the ACL-deficient state. Further, there were no significant differences in ATT and ITR between the three techniques utilized.

Conclusion

At time zero, ACL repair using the AL-CSF or IB-SAF technique with suture tape augmentation as well as BPTB ACL reconstruction each restored native anteroposterior and rotational laxity. In proximal ACL tears, both repair techniques with suture tape augmentation as an additional primary stabilizer were similar to ACL reconstruction.