Summary
The addition of the gracilis tendon to a semitendinosus tendon autograft is not associated with knee muscle strength, subjective knee function or revision surgery, but it may be associated with increased knee laxity after ACL reconstruction.
Abstract
Purpose
To evaluate and compare isokinetic knee muscle (extension and flexion) strength, single-leg-hop (SLH) test performance, anterior knee laxity, subjective knee function and the 2-year revision surgery risk between patients who underwent anterior cruciate ligament (ACL) reconstruction (ACLR) with a semitendinosus tendon autograft (ST) or a semitendinosus and gracilis tendon autograft (ST+G).
Methods
Patients aged 16 years or older who underwent primary ACLR with a hamstring tendon autograft at our institution from January 2005 to December 2020, with no associated ligament injuries, were identified. Isokinetic knee muscle strength and SLH test performance were assessed 6 months postoperatively. Anterior knee laxity (KT-1000 arthrometer, 134-N) was assessed preoperatively and 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and 1 and 2 years postoperatively. Patients who underwent revision ACLR at any institution in the country within 2 years of primary surgery were identified through the Swedish National Knee Ligament Registry.
Results
A total of 6,974 patients (5,479 ST and 1,495 ST+G) were included. There were no significant differences in extension and flexion strength or SLH test performance between the groups. Preoperatively, there was no significant difference in knee laxity between the ST and ST+G groups. Postoperatively, the ST+G group had a significantly increased mean side-to-side (STS) laxity (2.1 ± 2.3 mm vs 1.7 ± 2.2 mm; P <.001) and showed a trend towards an increased STS laxity according to the IKDC form, with significantly fewer patients with an STS laxity of = 2 mm (58.4% vs 65.8%) and significantly more patients with an STS laxity of between 3 and 5 mm (35.0% vs 29.9%) or > 5 mm (6.6% vs 4.3%) (P < .001). The only significant difference in subjective knee function was for the KOOS Quality of Life score in favor of the ST group preoperatively (37.3 ± 21.4 vs 35.1 ± 19.9; P = .001). No other significant differences between the groups were found preoperatively and 1 and 2 years postoperatively for any of the KOOS subscales. The overall revision ACLR rate within 2 years of primary surgery was 2.0% (138/6,974). The revision ACLR risk for the ST+G group (1.7%; 25/1,495) was not significantly different from that of the ST group (2.1%; 113/5,479) (Hazard Ratio [HR] 0.80; 95%, CI, 0.50-1.24; P = .32).
Conclusion
The addition of the gracilis tendon to an ST autograft was not associated with knee muscle strength, SLH test performance, subjective knee function or the risk of revision surgery, but it was associated with increased knee laxity after ACLR.