Objective

Numerous methods for independent femoral tunnel drilling have risen in popularity, including the use of a rigid reamer through an accessory anteromedial portal with hyperflexion (AM-RR) and the use of flexible reaming systems through a standard anteromedial portal (AM-FR). Recent cadaveric studies have suggested technical differences may result in AM-FR producing a more anatomic ACL graft position, longer and less vertical femoral tunnels, and decreasing the likelihood of posterior wall breakage or damage to posterolateral knee structures. The primary objective of this study was to compare graft failure rates at a minimum of 2 years postoperatively for patients undergoing ACL reconstruction between the two techniques. Secondary objectives were to compare functional performance testing outcomes, and patient reported outcome scores between patients with the two techniques.

Methods

IRB approval was obtained prior to beginning the study. 316 consecutive patients who underwent ACL reconstruction and participated in Lower-Extremity Assessment Protocol (LEAP) testing at a single academic institution from 2013 to 2018 were analyzed. Patients who underwent a primary, isolated ACL reconstruction were included. Patients were excluded if they underwent any additional ligamentous reconstruction or if they had less than 2 years of postoperative follow-up. The primary outcome measure was graft rupture, which was identified through chart review if available, and when not, through phone calls to the patients. Secondary outcome measures were functional testing, including maximal, isokinetic (90deg/sec) extension and flexion strength, limb symmetry indices (LSI) and single-leg hop tests obtained on average at 6 months postoperatively for all patients. IKDC and KOOS Scores were assessed for all patients at 6 months postoperatively at the time of functional testing and also evaluated. Comparison of categorical data was performed using a chi square test. Comparisons of continuous data were performed using a Student’s T test. For all comparison, p < 0.05 was considered significant.

Results

284 (AM-RR: 232; AM-FR: 52) patients were identified for inclusion to this study with an overall mean follow-up time of 3.7 ± 1.5 years and mean two-year follow-up rate of 91%. Overall, the two groups were not different, with the exception of a higher rate of patellar tendon grafts in the AM-FR group and longer mean follow-up in the AM-RR group [Table 1]. There was no significant difference in the rate of graft rupture between the use of AM-RR and AM-FR for femoral tunnel creation during ACL reconstruction (AM-FR: 9.6%, AM-RR: 10.8%; p = 0.806) [Table 2]. No significant differences existed in peak knee extension strength, peak knee flexion strength, limb symmetry indices, or hop testing between cohorts [Table 2]. No significant differences existed with regard to mean IKDC at 6 months (AM-RR: 81.1, AM-FR: 78.9; p = 0.269) or KOOS (AM-RR: 89.0, AM-FR 86.7; p = 0.104) between groups.

Conclusions

Independent femoral tunnel drilling for ACL reconstruction using rigid or flexible reaming systems results in comparable rates of graft rupture at a minimum of 2 years postoperatively and no significant differences in strength assessments at 6 months postoperatively.