Radiological evaluation of the femoral tunnel positioning in anterior cruciate ligament reconstruction

Effect of anteromedial portal location on femoral tunnel inclination, length, and location in hamstring autograft-based single-bundle anterior cruciate ligament reconstruction: a prospective study

BACKGROUND

Portal positioning in arthroscopic anterior cruciate ligament reconstruction is critical in facilitating the drilling of the femoral tunnel. However, the traditional approach has limitations. A modified inferior anteromedial portal was developed. Therefore, this study aims to compare the modified and conventional far anteromedial portals for femoral tunnel drilling, assessing factors such as tunnel length, inclination, iatrogenic chondral injury risk, and blowout.

MATERIAL AND METHODS

Patients scheduled for hamstring autograft-based anatomical single-bundle arthroscopic anterior cruciate ligament reconstruction were divided into two groups: modified and far anteromedial groups. Primary outcomes include differences in femoral tunnel length intraoperatively, tunnel inclination on anteroposterior radiographs, and exit location on lateral radiographs. Secondary outcomes encompass tunnel-related complications and reconstruction failures. To identify potential risk factors for shorter tunnel lengths and posterior exits, regression analysis was conducted.

RESULTS

Tunnel parameters of 234 patients were analyzed. In the modified portal group, femoral tunnel length and inclination were significantly higher, with tunnels exhibiting a more anterior exit position (p < 0.05). A higher body mass index exerted a negative influence on tunnel length and inclination. However, obese patients in the modified portal group had longer tunnels, increased inclination, and a lower risk of posterior exit. Only a few tunnel-related complications were observed in the far anteromedial group.

CONCLUSION

The modified portal allowed better control of tunnel length and inclination, ensuring a nonposterior femoral tunnel exit, making it beneficial for obese patients.

Anatomical Single-Bundle Transtibial Anterior Cruciate Ligament Reconstruction

Anatomical anterior cruciate ligament (ACL) reconstruction is a reasonable transition from isometric ACL reconstruction to obtain better clinical outcomes, and most authors believe that it can only be performed through the medial portal technique. However, in our clinical practice, we found that anatomical ACL reconstruction can be performed easily and accurately by creating a tibial tunnel, which is accomplished by setting the tibial tunnel with correct angulation to the sagittal plane and tibial axis. Hence, we introduce this special transtibial anatomical ACL reconstruction technique, in which the most critical step is the creation of a shallow tibial tunnel with a proximal projection to the anatomical location of the femoral tunnel. This technique is indicated for primary ACL reconstructions in skeletally mature patients. We believe this Technical Note will give a special view on anatomical ACL reconstruction.