Mid-term clinical and radiologic outcomes of augmented microfracture with decellularized particulated costal allocartilage for knee cartilage defects: four-year prospective case series

Augmented microfracture using decellularized particulated costal allocartilage has shown favorable short-term outcomes for knee cartilage defects, but evidence regarding its durability beyond 2 years remains limited. We aimed to evaluate the mid-term structural and clinical outcomes following augmented microfracture using decellularized particulated costal allocartilage. This prospective longitudinal single-arm study included 40 patients from the intervention arm of a previously conducted randomized controlled trial who were treated with augmented microfracture using decellularized particulated costal allocartilage. Magnetic resonance imaging (MRI) outcomes were assessed using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system at 1, 2, 3, and 4 years postoperatively. Patient-reported outcome measures (PROMs), including the Knee Injury and Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee score, and pain measured using a visual analog scale, were collected at baseline and at 1, 2, and 4 years. The mean MOCART total score peaked at 2 years (58.3 ± 10.3) and declined modestly thereafter, with 4-year scores (54.2 ± 14.2) remaining comparable to those at 1 and 3 years but significantly lower than those at 2 years ( p = 0.035). All PROMs improved significantly from baseline (all p < 0.001). KOOS total, symptom, and quality-of-life subscores continued to improve from 1 to 4 years ( p = 0.020, p = 0.006, and p = 0.048, respectively), while other subscores plateaued. Augmented microfracture using decellularized particulated costal allocartilage demonstrated MRI-assessed repair tissue quality that remained comparable at 1, 3, and 4 years despite a transient peak at 2 years, while clinical improvement was sustained through 4 years.