Summary
This study demonstrates that all HT graft configurations achieve comparable objective and subjective outcomes after ACLR. Therefore, the gracilis tendon can typically be preserved; however, if harvested, it does not compromise flexion strength or increase the risk of revision ACLR.
Abstract
Background
Limited research exists comparing subjective and objective outcomes in patients who underwent anterior cruciate ligament (ACL) reconstruction (ACLR) using different hamstring tendon (HT) graft configurations.
Purpose
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 risk between patients who underwent ACLR using different HT graft configurations.
Methods
Patients 16 years or older without concomitant ligament injuries who underwent primary ACLR with an HT autograft at our institution 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 (KOOS), 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 in the Swedish National Knee
Ligament Registry.
Results
A total of 5,673 patients (55.7% male) were included. The distribution of groups based on graft configuration was as follows: ST3 (tripled semitendinosus tendon) – 245 patients, ST4 (quadrupled semitendinosus tendon) – 4,359 patients, ST-G4 (doubled semitendinosus + doubled gracilis tendon) – 915 patients, and ST-G6 (quadrupled semitendinosus + doubled gracilis tendon) – 154 patients. Preoperatively, the groups showed no significant differences in laxity. Postoperatively, the ST-G4 and ST-G6 groups showed greater mean side-to-side (STS) laxity compared to the ST3 and ST4 groups (2.0 ± 2.4 mm and 1.7 ± 2.5 mm vs. 1.3 ± 2.1 mm and 1.5 ± 2.3 mm, respectively; P =.001), and fewer patients exhibiting STS laxity = 2 mm (59.3% and 60.9% vs. 74.9% and 70.7%, respectively, 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 statistically significant differences between the groups, though not clinically relevant, were observed in the preoperative Pain and Quality of Life subscales, as well as in the 1-year Symptoms subscale. No other significant differences between the groups were observed preoperatively or at 1, 2, or 5 years postoperatively across any of the KOOS subscales. The 5-year revision ACLR rates were as follows: ST4, 4.7% (207/4,359); 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 HT graft configurations (ST3, ST4, ST-G4, and ST-G6) led to similar subjective and objective outcomes following ACLR. The clinical significance of the slightly increased anterior knee laxity in the groups with gracilis tendon harvesting remains uncertain, as it did not correlate with subjective knee function or revision ACLR.