Five-Year Outcomes of Aragonite Scaffold vs Standard Care for Knee Lesions

Key Takeaways

• Greater 5-year improvement in overall KOOS was observed with the aragonite-based implant than with standard surgical care.
• The implant group had a 74.7% overall KOOS responder rate versus 29.6% with standard surgical care, while treatment failure was 15.0% versus 35.7%.
• Secondary patient-reported outcomes also favored the implant, and the mild to moderate osteoarthritis subgroup showed the same directional pattern for responder and failure outcomes.

Five-year results from an aragonite-based knee scaffold trial showed greater overall KOOS improvement with the implant than with standard surgical care, reaching final scores of 81.0 ± 23.0 versus 59.1 ± 25.2. Adults with focal chondral or osteochondral knee lesions were randomized to the implant or to arthroscopic debridement or microfracture as standard surgical care. The between-group improvement difference was 22.6 points, with a 95% CI of 16.6 to 28.7 at 5 years. Responder and treatment-failure outcomes also favored the implant over the same follow-up period.

In this Level 1 multicenter randomized comparison, patients were enrolled at 26 centers across 8 countries and assigned treatment in a 2:1 ratio. Standard surgical care consisted of arthroscopic debridement or microfracture, and treatment counts were 167 for the implant and 84 for standard surgical care. Eligible adults were 21 to 75 years old with up to 3 ICRS grade 3a or higher defects on the femoral condyles and or trochlea. The total treatable area ranged from 1 to 7 cm2, bony defect depth was 8 mm or less, and Kellgren-Lawrence scores ranged from 0 to 3. The primary endpoint was improvement in overall KOOS, and secondary endpoints included responder rate, KOOS subscales, IKDC subjective score, treatment failure, and treatment-emergent adverse events.

Baseline overall KOOS values were similar between groups at 41.2 ± 13.1 for the implant and 41.7 ± 12.4 for standard surgical care. Five-year follow-up compliance was 88.4% in the implant group and 83.1% in the standard-care group. Responders were defined as patients with at least 30 points of improvement in overall KOOS. All secondary patient-reported outcome measures favored the implant, including KOOS subscales and the IKDC subjective score. The same pattern was seen across the reported patient-reported endpoints at the 5-year assessment.

The covariate analysis compared patients with no to minimal osteoarthritis against those with mild to moderate osteoarthritis. Within the mild to moderate osteoarthritis subgroup, responder rates were 74.6% with the implant and 36.2% with standard surgical care. Failure rates in that subgroup were 13.2% and 40.7%, respectively (P < .001). Investigators described the scaffold as safe and superior to standard surgical care through 5 years, although specific treatment-emergent event counts were not provided. Across adults with focal chondral or osteochondral knee lesions, long-term patient-reported outcomes, responder rates, and failure outcomes favored the implant during randomized follow-up.