The effect of initial graft tension after anterior cruciate ligament reconstruction: a randomized clinical trial with 36-month follow-up.

Background: The initial graft tension applied at the time of anterior cruciate ligament (ACL) reconstruction alters joint contact and may influence cartilage health. The objective was to compare outcomes between 2 commonly used "laxity-based" initial graft tension protocols.

Hypotheses: (1) The high-tension group would have less knee laxity, improved clinical and patient-oriented outcomes, and less cartilage damage than would the low-tension group after 36 months of healing. (2) The outcomes of the high-tension group would be equivalent to those of a matched control group.

Study Design: Randomized controlled trial; Level of evidence, 1.

Methods: Ninety patients with isolated unilateral ACL injuries were randomized to undergo ACL reconstruction using 1 of 2 initial graft tension protocols: (1) autografts tensioned to restore normal anterior-posterior (AP) laxity at the time of surgery (ie, low tension; n = 46) and (2) autografts tensioned to overconstrain AP laxity by 2 mm (ie, high tension; n = 44). Sixty matched healthy patients formed the control group. Outcomes were assessed preoperatively, intraoperatively, and at 6, 12, and 36 months after surgery.

Results: No significant differences were found between the 2 initial graft tension protocols for any of the outcome measures at 36 months. However, there were differences when comparing the 2 treatment groups to the control group. On average, AP laxity was 2 mm greater in the ACL-reconstructed groups than in the control group (P < .007). International Knee Documentation Committee (IKDC) knee evaluation scores, peak isokinetic knee extension torques, and 4 of 5 Knee Osteoarthritis Outcome Scores (KOOS) were significantly worse than the control group (P < .001, P < .027, and P < .05, respectively). Short Form-36 Health Survey (SF-36) scores and reinjury rates were similar between groups at 36 months. Although there were significant changes in radiography and magnetic resonance imaging present in the ACL-reconstructed knees of both treatment groups, the magnitude was relatively small and likely clinically insignificant at 36 months.

Conclusion: Both laxity-based initial graft tension protocols produced similar outcomes without fully restoring joint function or patient-oriented outcomes (KOOS) when compared with the control group. There was minimal evidence of cartilage damage 36 months after surgery.