A Numerical Investigation of Anatomic Anterior Cruciate Ligament Reconstruction

Anterior Cruciate Ligament (ACL) reconstruction by anatomic method is the most popular method of reconstruction. This method of ACL reconstruction utilizes Anteromedial Portal (AMP) techniques.

In this study, five human subjects with healthy knee joints were considered on which Lachman test was simulated. Traditional Transtibial (TT) and AMP techniques were simulated in this study. The mean value of Von – Mises stress on the ACL was calculated. ACL reconstruction using hamstring tendon graft was simulated in a finite element analysis on four healthy human knee joints. Magnetic Resonance Images (MRI) of knee joints of four healthy human subjects were analyzed in this study for statistical significance of the results. Both techniques were simulated in each of the subjects. The hamstring tendon graft used had a diameter of 9 mm. The tibial foot print was 44.6 ± 2.5% from the anterior margin and 48 ± 3% from the medial margin. The femoral foot print was calculated based on Mochizuki’s method at 38.7 ± 2.7% from the deep subchondral margin.

The obliquity of reconstructed – ACL (R – ACL) to the tibial plateau for AM technique was in the range of 51 to 58 degrees in the sagittal plane and 69 to 76 degrees in the coronal plane. In the case of TT technique, it was in the range of 59 to 69 degrees in the coronal plane and 72 to 78 degrees in the coronal plane in the femur. Similarly, the sagittal obliquity of R – ACL in the tibia was 55 degrees. The mean Von–Mises stress in the R – ACL for AMP technique was 17.74 ± 3.01 MPa. The stresses in the R – ACL for AMP technique is consistently near to the mean stress in the intact ACL. Whereas, stresses in the R – ACL used in TT technique are not consistently near to the stresses in the intact ACL of a healthy human knee joint.

Hence, AMP technique is the better technique between AMP and TT techniques of ACL reconstruction.