Radiologic and clinical evaluation of anatomic and transtibial ACL reconstruction in a population excluding professional athletes

Abstract

Objectives: Two different approaches for drilling the femoral tunnel are commonly used in single-bundle anterior cruciate ligament (ACL) reconstruction: creating the femoral tunnel through the tibial tunnel or drilling the tunnel through a low anteromedial portal. The purpose of this retrospective study was to compare the radiological and clinical outcomes of hamstring ACL reconstruction using the transtibial (TT) versus the anteromedial portal (AM) technique for drilling the femoral tunnel by two different surgeons in non-professional athletes. Methods: Using the elevator system with hamstring tendons, single-bundle ACL reconstruction was applied to 24 patients with the TT technique and to 15 patients with the AM technique. Radiological outcome was evaluated by the postoperative X-rays and MRI images at the 6-9 month and clinical outcomes by the modified Cincinnati Knee Score. The angle made by the tunnel with the anatomic axis of the femur (FTA) and the angle made by the tunnel with the anatomic axis of the tibia (TTA) were examined on direct radiographs and the angular difference between the tunnels was evaluated. On MRI, evaluation was made of the anterior length in the sagittal plane of the exit point of the tibial tunnel in the joint (TAS) in ratio to the whole plateau (TSR) and the posterior length in the sagittal plane of the entrance point of the femoral tunnel in the femoral lateral condyle (FPS) in ratio to the anterior posterior diameter of the whole condyle (FCR) and the height of the lateral condyle location in the sagittal plane (FH). Results: The FH height ratio of the TT group was statistically significant when compared to the AM group (p<0.01). No statistically significant difference was found between the groups in respect of FPS (p>0.05). The mean femoral tunnel angle of the AM group was statistically significant compared to that of the TT group (p<0.01). The mean tibial tunnel angle of the TT group was statistically significant compared to that of the AM group (p<0.01). The angular difference of the AM group was statistically significant compared to that of the TT group (p<0.01). In both the AM and TT groups, the increase seen in the postoperative clinical scores compared to the preoperative scores was determined to be statistically significant (p<0.01). No statistically significant relationship was determined in either the AM group or the TT group between the postoperative clinical scores and the femoral tunnel angle, the tibial tunnel angle and the angular difference (p>0.05). Conclusion: When using a transtibial drilling technique, the location of the femoral tunnel is restricted by the angulation of the tibial tunnel in the coronal plane and may lead to a high placement of the femoral tunnel in a non-anatomical position. The use of the anteromedial portal (AMP) for the femoral drilling provides the surgeon with more freedom to anatomically place the tunnel in the natural femoral ACL footprint, thus improving rotational stability. In this early stage study of individuals not participating in professional sports, although a significant difference was seen in favour of the anatomic group, in the radiological measurements between the anatomic and transtibial groups, no significant difference was determined in respect of clinical results. This can be considered to be due to a low requirement for rotational stability in individuals who do not participate sports.