Summary

During ACL reconstruction, high volume surgeons more commonly place the femoral tunnel in an anatomic position compared to low volume surgeons.

Abstract

Background

Placement of the femoral and tibial tunnels in the anatomic footprint during anterior cruciate ligament reconstruction (ACLR) is paramount for restoring rotatory knee stability. Recent studies have looked at surgeon volume and its outcomes on procedures such as total knee arthroplasty and infection rates, but very few studies have specifically examined tunnel placement after ACLR based on surgeon volume.

Purpose

To compare the placement of femoral and tibial tunnels during ACLR between high volume and low volume surgeons. It was hypothesized that high volume surgeons would have more anatomic tunnel placement compared to low volume surgeons.

Methods

A retrospective review was conducted of all ACLR performed between 2015 and 2019 at an integrated health care system consisting of both academic and community hospitals with 68 orthopedic surgeons. Surgeon volume was categorized as less than 12 ACLR per year (low volume) and 12 or more ACLR per year (high volume). Femoral tunnel placement for each patient was determined using a strict lateral radiograph (less than 6mm of offset between the posterior halves of the medial and lateral condyles) taken after the primary ACLR using the quadrant method. The center of the femoral tunnel was measured in relation to the posterior-anterior (PA) and proximal-distal (PD) dimensions (normal center of anatomic footprint: PA 25% and PD 29%). Tibial tunnel placement for each patient was determined on the same lateral radiographs by measuring the mid-sagittal tibial diameter and the center of the tibial attachment area of the ACL from the anterior tibial margin (normal center of anatomic footprint: 43%). Each lateral radiograph was reviewed by 1 of 3 blinded reviewers.

Results

A total of 4500 patients were reviewed, of which 688 patients had adequate postoperative radiographs and were included in the final analysis. There were 254 patients in the low volume group and 434 patients in the high volume group. Low volume surgeons performed a mean of 4 ACLRs per year, whereas surgeons in the high volume group performed a mean of 36 ACLRs per year. In the PA dimension, the low volume group had statistically significant more anterior femoral tunnel placement compared with the high volume group (31% ± 10% vs. 28% ± 9%, p<0.01). In the PD dimension, the low volume group had statistically significant more proximal femoral tunnel placement compared to the high volume group (32% ± 9% vs 35% ± 9%, p<0.01). For the tibial tunnel, the low volume group had statistically significant more posterior tibial tunnel placement compared to the high volume group (40% ± 9% vs 38% ± 6%, p<0.01).

Conclusion

Low volume surgeons placed their femoral tunnels statistically significantly more anterior and proximal (high) during ACLR, as well as statistically significantly placed their tibial tunnels more posterior, compared to high volume surgeons. Prior research has indicated anatomic placement of the femoral and tibial tunnels during ACLR leads to improved rotatory knee stability. The findings of this study demonstrate the importance of surgical volume and experience during ACLR, and ACLR should be preferentially pursued in high volume centers.