Propensity for Clinically Meaningful Improvement and Surgical Failure After Anterior Cruciate Ligament Repair

Abstract

Background: Primary repair of the anterior cruciate ligament (ACL) confers an alternative to ACL reconstruction in appropriately selected patients.

Purpose: To prospectively assess survivorship and to define the clinically meaningful outcomes after ACL repair.

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

Methods: Included were consecutive patients with Sherman grade 1-2 tears who underwent primary ACL repair with or without suture augmentation between 2017 and 2019. Patient-reported outcomes (Lysholm, Tegner, International Knee Documentation Committee, Western Ontario and McMaster Universities Osteoarthritis Index, and Knee injury and Osteoarthritis Outcome Score [KOOS] subscales) were collected preoperatively and at 6 months, 1 year, and 2 years postoperatively. The minimal clinically important difference (MCID) was calculated using a distribution-based method, whereas the Patient Acceptable Symptom State (PASS) and substantial clinical benefit (SCB) were calculated using an anchor-based method. Plain radiographs and magnetic resonance imaging (MRI) were obtained at 6 months, 1 year, and 2 years postoperatively.

Results: A total of 120 patients were included. The overall failure rate was 11.3% at 2 years postoperatively. Changes in outcome scores required to achieve the MCID ranged between 5.1 and 14.3 at 6 months, 4.6 and 8.4 at 1 year, and 4.7 and 11.9 at 2 years postoperatively. Thresholds for PASS achievement ranged between 62.5 and 89 at 6 months, 75 and 89 at 1 year, and 78.6 and 93.2 at 2 years postoperatively. Threshold scores (absolute/change based) for achieving the SCB ranged between 82.8 and 96.4/17.7 and 40.1 at 6 months, between 94.7 and 100/23 and 45 at 1 year, and between 95.3 and 100/29.4 and 45 at 2 years. More patients achieved the MCID and PASS at 1 year compared with 6 months and 2 years. For SCB, this trend was also observed for non-KOOS outcomes, while for KOOS subdomains, more patients achieved the SCB at 2 years. High-intensity signal of the ACL repair (odds ratio [OR], 31.7 [95% CI, 1.5-73.4]; P = .030) and bone contusions on MRI (OR, 4.2 [95% CI, 1.7-25.2]; P = .041) at 1 year postoperatively were independently associated with increased risk of ACL repair failure.

Conclusion: The rate of clinically meaningful outcome improvement was high early after ACL repair, with the greatest proportion of patients achieving the MCID, PASS, and SCB at 1 year postoperatively. Bone contusions involving the posterolateral tibia and lateral femoral condyle as well as high repair signal intensity at 1 year postoperatively were independent predictors of failure at 2 years postoperatively.

Keywords: ACL; MCID; PASS; SCB; clinical outcomes; repair.

Figure 1.

Magnetic resonance imaging scans of an acute, proximal anterior cruciate ligament (ACL) tear. (A-D) Coronal T2 weighted images with sequences progressing posteriorly to anteriorly demonstrating edema in the proximal aspect of the ACL. (E-F) T1-weighted sagittal images demonstrating attenuation in the proximal one-third of the ACL.

Figure 2.

Arthroscopic images of an isolated anterior cruciate ligament (ACL) repair. (A) Arthroscopic confirmation of proximal ACL tear using probe. (B) Bunnel-type suture introduced into anteromedial and posterolateral bundles. (C, D) Knotless anchor being introduced into femoral tunnel and tightened.

Figure 3.

Arthroscopic images of an anterior cruciate ligament repair augmented with Ultratape augmentation. (A, B) Ultratape being introduced into anchor repairing the anteromedial bundle and subsequently being grabbed with suture retriever. (C, D) Ultratape subsequently passed into tibial tunnel and tightened with biotenodesis screw.

Figure 4.

Fill-plot demonstrating improvement in patient-reported outcome scores preoperatively to 6 months, 1 year, and 2 years after anterior cruciate ligament repair. Error bars represent the SD of the mean, whereas points across the line demonstrate the mean value of each outcome, respectively. The shaded areas represent the improvement in scores over time. Preoperative scores were the lowest, and scores significantly increased at 6 months, 1 year, and 2 years postoperatively. ADL, Activities of Daily Living; IKDC, International Knee Documentation Committee; KOOS, Knee injury and Osteoarthritis Outcome Score; QOL, Quality of Life; Sport, Sport and Recreation; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Figure 5.

Magnetic resonance imaging scan finding 1 year postoperatively of a right knee demonstrating a large area of bony edema in the posterolateral tibial plateau, with a lesser degree of edema at the medial aspect of the lateral femoral condyle.