Chondral Defect Repair with Particulated Juvenile Cartilage Allograft: Mid-term MRI and T2 Mapping Analysis

OBJECTIVES: To evaluate the functional outcomes and morphologic appearance of repair tissue in patients with symptomatic knee articular cartilage defects treated with minced juvenile articular cartilage (DeNovo NT). METHODS: Thirty-four patients underwent treatment of cartilage defects of the knee with minced juvenile articular cartilage allograft. Mean postoperative follow up was 33.6 months. MRIs were obtained at 24-months (16 patients) and 48-months or greater (13 patients). MRIs were evaluated for greyscale cartilage repair assessment score and quantitative T2 mapping. Baseline clinical outcome scores (IKDC, ADL, Marx Activity Rating Scale) were obtained prior to surgery, and at a minimum follow up interval of 24-months. RESULTS: The mean IKDC and ADL scores significantly improved following surgery. The magnitude of improvement in IKDC scores was 30 (Std Dev 31). The Marx activity Rating Scale score demonstrated a resumption of pre-operative activity levels, Figure 1a. Donor age had no significant effect on functional outcomes scores of treated patients. MRI assessment revealed greater than 66% lesion fill (a score of 2) in 80% of patients. A trend toward significance in difference in % lesion fill was observed when patients were grouped according to donor age ≤ 5 vs. > 5 years (p = 0.09), Figure 1b. Lesion fill did not correlate with functional outcome score. Using one-way analysis of variance with post-hoc testing, a significant difference was found between T2 mapping of the deep zones of the graft and normal cartilage (p=0.003), Table 1. CONCLUSION: Functional outcome scores significantly improved in patients treated with minced juvenile articular cartilage (De Novo NT) for the treatment of symptomatic articular cartilage lesions of the knee. Activity levels, as noted by the Marx Activity Scale were preserved. Morphologic analysis demonstrated greater than 66% lesion fill in 80% of the patients studied. T2 mapping demonstrated the sensitivity to assess differences between repair tissue and native cartilage.