Five-Year Follow-up of a Multicenter Randomized Controlled Trial Comparing an Aragonite-Based Scaffold With Microfracture and Debridement for Chondral and Osteochondral Knee Lesions

Background: Chondral/osteochondral knee lesions are commonly encountered and often associated with progression of osteoarthritis (OA). Nevertheless, knee repair trials have traditionally excluded patients with concurrent mild to moderate OA. Purpose: To compare the clinical and safety outcomes of knee repair with an aragonite-based osteochondral implant with outcomes of surgical standard of care (SSOC) in patients with chondral/osteochondral knee lesions, including those with mild to moderate OA. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Investigators at 26 centers across 8 countries enrolled adult patients (21-75 years of age) with ≤3 cartilage defects of International Cartilage Regeneration & Joint Preservation Society grade ≥3a located on the femoral condyles and/or trochlea, total treatable area 1 to 7 cm 2 , bony defect depth ≤8 mm, and Kellgren-Lawrence knee OA score of 0 to 3. Patients were randomized 2:1 to receive an aragonite-based implant or SSOC (arthroscopic debridement or microfracture) and followed for 5 years. The primary endpoint was improvement in overall Knee injury and Osteoarthritis Outcome Score (KOOS). Secondary endpoints included percentage of responders (minimum overall KOOS improvement ≥ 30 points), patient-reported outcomes (KOOS subscale values and International Knee Documentation Committee subjective score), treatment failure (ie, need for any secondary treatment), and treatment-emergent adverse events. A covariate analysis compared primary/secondary outcomes between patients with no to minimal and mild to moderate OA. Results: In total, 167 patients underwent knee repair with the study implant and 84 with SSOC, with follow-up compliance rates of 88.4% and 83.1%, respectively, at 5 years. The mean baseline overall KOOS values were comparable between the implant (41.2 ± 13.1) and SSOC (41.7 ± 12.4) groups. By the final follow-up, improvement was significantly greater for the implant group (81.0 ± 23.0 vs 59.1 ± 25.2; 22.6-point difference; 95% CI, 16.6-28.7). The overall KOOS responder rate was 74.7% in the implant group and 29.6% in the SSOC group. The implant group experienced significantly superior outcomes between baseline and the final follow-up for all secondary patient-reported outcome measures. Treatment failure rate was significantly higher with SSOC than the implant (35.7% vs 15.0%; P < .001). Among patients with mild to moderate OA, the implant group exhibited a higher overall KOOS responder rate (74.6% vs 36.2%) and lower failure rate (13.2% vs 40.7%; P < .001) than the SSOC group. Conclusion: The results confirmed that the aragonite-based scaffold is both safe and superior to SSOC in improving clinical outcomes at up to 5 years’ evaluation, as well as in patients with mild to moderate OA.