Summary

Knee hyperextension is not associated with inferior outcomes after ACLR with HT autografts

Abstract

Background

There is concern that physiologic knee hyperextension may be associated with inferior outcomes after anterior cruciate ligament reconstruction (ACLR) using hamstring tendon (HT) autografts.

Purpose

To assess whether there is an association between preoperative knee hyperextension (≤-5°) and postoperative anterior knee laxity, subjective knee function, or revision surgery after ACLR using HT autografts.

Methods

Patients without concomitant ligament injuries who underwent primary ACLR using an HT autograft at (xxx-blinded for review-xxx) between January 1, 2005, and December 31, 2018, were identified. The cohort was dichotomized into the hyperextension group (≤-5°) and the no hyperextension group (>-5°) depending on preoperative contralateral passive knee extension degree. Anterior knee laxity (KT-1000 arthrometer; 134 N) was assessed preoperatively and at 6 months postoperative. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at 1, 2, and 5 years postoperative. Patients who underwent revision ACLR at any institution in the country within 5 years of the primary surgery were identified in the (xxx-blinded for review-xxx).

Results

A total of 6,104 patients (53.4% males) for whom knee range of motion measurements were available were identified (hyperextension group [≤-5°]: 2,350 [38.5%]; mean extension, -6.1° ± 2.3° [range, -20° to -5°]; no hyperextension group [>-5°]: 3,754 [61.5%]; mean extension, 0° ± 1.4° [range, -4° to 15°]). There were no intergroup differences in knee laxity preoperatively (hyperextension group, 3.6 ± 2.8 mm; no hyperextension group, 3.7 ± 2.7 mm; P = .24) or postoperatively (hyperextension group, 1.8 ± 2.3 mm; no hyperextension group, 1.8 ± 2.2 mm; P = .41). The only significant but non-clinically relevant intergroup differences were seen in the KOOS Symptoms subscale at the 1-year follow-up (hyperextension group, 81.4 ± 16.0; no hyperextension group, 80.3 ± 16.5; P = .03) and in the Sports and Recreation subscale at the 5-year follow-up (hyperextension group, 73.0 ± 25.6; no hyperextension group, 75.7 ± 24.3; P = .02). No other significant intergroup differences were noted preoperatively or at 1, 2, or 5 years postoperative in any of the KOOS subscales. The overall revision ACLR rate within 5 years of the primary surgery was 4.9% (302/6,104 patients). The hazard for revision ACLR in the no hyperextension group (4.5% [170/3,754] patients) was not significantly different from that in the hyperextension group (5.6% [132/2,350] patients) (hazard ratio [HR], 0.89; 95% confidence interval [95% CI], 0.71–1.12; P = .34). A subsequent sub-analysis showed that the hazard of revision ACLR in patients with no hyperextension was not significantly different from that of patients with ≤-10° of extension (5.7% [27/467] patients) (HR, 0.91; 95% CI, 0.61–1.36; P = .65).

Conclusion

Preoperative passive contralateral knee hyperextension (≤-5°) was not associated with postoperative anterior knee laxity, subjective knee function, or revision surgery up to 5 years after ACLR using HT autografts.