Oval femoral tunnel technique is superior to the conventional round femoral tunnel technique using the hamstring tendon in anatomical anterior cruciate ligament reconstruction

This study was conducted to compare the efficacy between the oval femoral tunnel technique and the conventional round femoral tunnel technique in ACL reconstruction using an autologous hamstring tendon on the basis of the postoperative clinical outcomes and ACL graft tendon maturity. The hypothesis was that ACL reconstruction performed using the oval femoral tunnel technique was better than that performed using the round femoral tunnel technique in clinical functions and graft maturity.

One hundred and eight patients who underwent anatomical single-bundle ACL reconstruction were included in this study and the follow-up period was at least 2 years. Thirty-nine patients admitted between February and August in 2016 were included in the oval femoral tunnel group and 69 patients admitted between September 2016 and March 2017 were included in the round femoral tunnel group. The Lachman test result, pivot-shift test result, Lysholm score, IKDC score, and VAS score were used for the clinical evaluation. An objective assessment of anteroposterior stability was performed using a KT1000 arthrometer. Postoperative MRI was conducted to compare the ACL graft maturity differences between the oval femoral tunnel group and round femoral tunnel group, where the signal/noise quotient (SNQ) was calculated. In addition, second-look arthroscopy was conducted to compare the graft status and synovial coverage at 24 months postoperatively.

All the patients presented with significant improvement in all clinical scores from the preoperative period to the 24-month follow-up. During the postoperative follow-up period, no statistically significant differences were found between the two groups in terms of the VAS score, knee ROM, Lachman test results, and graft status determined in the second-look arthroscopic evaluation. The Lysholm score was 97.1 ± 3.9 and 94.8 ± 5.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the 24-month follow-up (p = 0.031). The IKDC subjective score was 92.0 ± 2.6 and 89.0 ± 3.6 in the oval femoral tunnel group and round femoral tunnel group, respectively, at the end of the follow-up period (p < 0.001). Significantly more patients with 1-degree positive pivot-shift test results were observed in the round femoral tunnel group (10/65) than in the oval femoral tunnel group (1/37) at the end of the follow-up period (p = 0.048). The mean SNQ of the oval femoral tunnel group was 2.7 ± 0.9, which was significantly lower than that of the round femoral tunnel group (3.6 ± 1.1) at the 24-month postoperative follow-up (p < 0.001).

Based on the clinical evaluations, MRI findings and second-look arthroscopy results of the two groups, the oval femoral tunnel technique yielded significantly better knee function and knee laxity restoration and more mature ACL grafts than the round femoral tunnel technique, whereas no significant differences were found at the second-look arthroscopy.

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