Outcomes After Isolated Acute Anterior Cruciate Ligament Reconstruction Are Inferior in Patients With an Associated Anterolateral Ligament Injury

Background: Isolated reconstruction of the anterior cruciate ligament (ACL) does not reestablish the normal knee biomechanics in cases of associated injuries to the anterolateral structures. Studies evaluating the potential clinical effect of anterolateral ligament (ALL) injury on the treatment of ACL injuries are necessary to validate the findings of biomechanical studies. Purpose: To evaluate the clinical outcomes and failure rate of ACL reconstruction in patients with and without ALL injury diagnosed using magnetic resonance imaging. Study Design: Cohort study; Level of evidence, 2. Methods: A prospective cohort of patients with acute ACL injury was divided into 2 groups based on the presence (ALL group) or absence (no-ALL group) of ALL injury on preoperative magnetic resonance imaging scans. Both groups underwent anatomic reconstruction of the ACL with autologous hamstring tendon grafts. The Lysholm and subjective IKDC scores (International Knee Documentation Committee), KT-1000 arthrometer and pivot-shift test results, reconstruction failure rate, incidence of contralateral ACL injury, presence of associated meniscal injury, and presence of knee hyperextension were evaluated. Results: A total of 182 patients were evaluated. Postoperative mean ± SD follow-up was 33.6 ± 7.1 and 36.1 ± 8.1 months for the ALL and no-ALL groups, respectively. No significant differences were found between the groups in terms of age, sex, knee hyperextension, duration of injury before reconstruction, follow-up time, or associated meniscal injuries. In the preoperative evaluation, the pivot-shift grade was similar, and the ALL group had worse KT-1000 arthrometer values (7.9 ± 1.2 mm vs 7.2 ± 1.1 mm; P < .001). In the postoperative evaluation, patients in the no-ALL group had a lower reconstruction failure rate (10.2% vs 1.4%; P = .029) and better clinical outcomes according to the IKDC subjective (85.5 ± 10.7 vs 89.1 ± 6.6; P = .035) and Lysholm scores (85.9 ± 10.1 vs 92.0 ± 6.3; P < .001). There was no postoperative difference in the KT-1000 or pivot-shift results. Conclusion: Combined ACL and ALL injuries were associated with significantly less favorable outcomes than were isolated ACL injuries at a minimum follow-up of 2 years after ACL reconstruction. Patients with concomitant ALL injury showed a higher rerupture rate and worse functional scores.