Comparable Outcomes Across 4 Hamstring Tendon Graft Configurations in ACL Reconstruction, Despite Increased Knee Laxity With Gracilis Tendon Harvesting.

Abstract

Background: There is a lack of studies that have thoroughly compared subjective and objective outcomes in patients undergoing anterior cruciate ligament reconstruction (ACLR) using different hamstring tendon (HT) graft configurations.

Purpose/hypothesis: The purpose of this study was to compare anterior knee laxity, isokinetic knee extension and flexion strength, single-leg hop (SLH) test performance, subjective knee function, and the 5-year revision surgery rates between patients who underwent ACLR using 4 HT graft configurations. It was hypothesized that there would be no significant differences in the outcomes examined between the groups.

Study design: Cohort study; Level of evidence, 3.

Methods: Patients ≥16 years without concomitant ligamentous injuries who underwent primary ACLR with an HT autograft at Capio Artro Clinic, Stockholm, Sweden, between January 1, 2005, and December 31, 2018, were identified. Anterior knee laxity was evaluated using the KT-1000 arthrometer (134 N) both preoperatively and at 6 months postoperatively. Isokinetic knee extension and flexion strength, along with SLH test performance, were evaluated 6 months postoperatively. Subjective knee function was evaluated using the Knee injury and Osteoarthritis Outcome Score, which was collected preoperatively and at 1, 2, and 5 years postoperatively. Revision ACLRs performed at any institution in Sweden within 5 years of the primary surgery were captured using the Swedish National Knee Ligament Registry.

Results: A total of 5673 patients (55.7% male) were included: tripled semitendinosus tendon (ST3), 245 patients; quadrupled semitendinosus tendon (ST4), 4359 patients; doubled semitendinosus + doubled gracilis tendon (ST-G4), 915 patients; and quadrupled semitendinosus + doubled gracilis tendon (ST-G6), 154 patients. Preoperatively, the groups showed no significant differences in anterior knee laxity. Postoperatively, the ST-G4 and ST-G6 exhibited greater mean anterior side-to-side (STS) laxity and increased STS laxity based on the International Knee Documentation Committee examination form, with fewer patients showing STS laxity ≤2 mm and more patients having STS laxity between 3 and 5 mm and >5 mm (P <.001). No significant differences were found between the groups in terms of extension and flexion strength or SLH test performance. Regarding subjective knee function, the only significant differences between the groups, though not clinically relevant (<8-10 points), were observed in the preoperative Pain and Quality of Life subscales of the KOOS, as well as in the 1-year Symptoms subscale. The 5-year revision ACLR rates were as follows: ST4, 4.7% (207/4359); ST3, 5.3% (13/245); ST-G4, 3.7% (34/915); and ST-G6, 5.8% (9/154). The hazard of revision ACLR within 5 years of primary surgery in the ST3, ST-G4, and ST-G6 groups was not significantly different from that of the ST4 group (reference group).

Conclusion: All 4 HT graft configurations (ST3, ST4, ST-G4, and ST-G6) yielded comparable outcomes in isokinetic knee flexion and extension strength, SLH test performance, subjective knee function, and the hazard of revision surgery after ACLR. The groups that underwent gracilis tendon harvesting (ST-G4 and ST-G6) exhibited increased anterior knee laxity at 6 months compared with the groups that did not (ST3 and ST4). However, the clinical significance of this finding remains uncertain, as the greater knee laxity did not correlate with subjective knee function or revision ACLR.