15-Year Follow-up of Neuromuscular Function in Patients With Unilateral Nonreconstructed Anterior Cruciate Ligament Injury Initially Treated With Rehabilitation and Activity Modification

Abstract

Background: It has been suggested that neuromuscular function is of importance in the overall outcome after anterior cruciate ligament (ACL) injury.

Hypothesis: Good neuromuscular function can be achieved and maintained over time in subjects with ACL injury treated with rehabilitation and activity modification but without reconstructive surgery.

Study Design: Case series; Level of evidence, 4.

Methods: One hundred consecutive patients (42 women and 58 men) with acute ACL injury at a nonprofessional, recreational or competitive activity level were assessed 1, 3, and 15 years after injury. Their mean age at inclusion was 26 years (range, 15-43 years). All patients initially underwent rehabilitation and were advised to modify their activity level, especially by avoiding contact sports. Patients with recurrent giving-way episodes or secondary meniscal injuries that required fixation were subsequently excluded and underwent reconstruction of the ACL. Sixty-seven patients (71% of those available for follow-up) with unilateral nonreconstructed injury remained at the 15-year follow-up. Fifty-six of these 67 patients were examined with the single-legged hop test for distance and knee muscle strength. The limb symmetry index (LSI), calculated by dividing the result for the injured leg by that of the uninjured leg and multiplying by 100, was used for comparisons over time (paired t test).

Results: The LSI for the single-legged hop test was higher at the 3-year follow-up (mean, 98.5%; standard deviation [SD], 7.6%) than at the 15-year follow-up (mean, 94.8%; SD, 10.5%) (mean difference, —3.7%; 95% confidence interval [CI], —6.1% to —1.2%; P = .004). The LSI for isometric extension was higher at the 15-year follow-up (mean, 97.2%; SD, 13.7%) than at the 1-year follow-up (mean, 88.2%; SD, 15.4%) (mean difference, 9.0%; 95% CI, 3.7% to 14.4%; P = .001). At the 15-year follow-up, between 69% and 85% of the patients had an LSI ≥90%.

Conclusions: Good functional performance and knee muscle strength can be achieved and maintained over time in the majority of patients with ACL injury treated with rehabilitation and early activity modification but without reconstructive surgery.