A Prospectively Randomized Double-Blind Study on the Effect on Initial Graft Tension on Knee Stability After Anterior Cruciate Ligament Reconstruction.

Background: No consensus exists on the amount of tension that should be applied to anterior cruciate ligament grafts to best facilitate graft incorporation and re-create normal knee mechanics. Hypothesis: Differences in initial graft tension will affect postoperative knee stability. Study Design: Prospective, randomized, double-blind clinical trial. Methods: Forty-nine patients undergoing bone-patellar tendon-bone autograft anterior cruciate ligament reconstruction by a single surgeon were randomized into high-tension (n = 27) and low-tension (n = 22) groups. Grafts were set at 90 N or 45 N. Arthrometric measurements (KT-1 000 arthrometer manual maximum) of anterior tibial displacement and knee range of motion were made before surgery and at 1 week and an average of 20 months after surgery. Knee outcome scores were collected before and after surgery, and a single-leg hop test was also performed at final follow-up. Results: After anterior cruciate ligament reconstruction, anterior tibial displacement was significantly greater in the patients in the low-tension group (P < .05). The side-to-side difference in anterior tibial displacement in the high-tension and low-tension groups was 1.1 ± 1.7 mm versus 2.4 ± 2.4 mm I week after surgery and 2.2 ± 1.6 mm versus 3.0 ± 2.2 mm at follow-up. Five patients had abnormal anterior tibial displacement (>5 mm side-to-side difference), and all were in the low-tension group (P < .05). Knee outcome scores improved with surgery (P < .01), with similar results for low-tension and high-tension groups. Hop test deficits were not different between groups. Conclusions: Initial graft tension affects the restoration of knee stability. A graft tension of 45 N was not sufficient for restoring knee stability. [ABSTRACT FROM AUTHOR]