NeoCart, an autologous cartilage tissue implant, compared with microfracture for treatment of distal femoral cartilage lesions: an FDA phase-II prospective, randomized clinical trial after two years

Background: Despite introduction of autologous chondrocyte therapy for repair of hyaline articular cartilage injury in 1994, microfracture remains a primary standard of care. NeoCart, an autologous cartilage tissue implant, was compared with microfracture in a multisite prospective, randomized trial of a tissue-engineered bioimplant for treating articular cartilage injuries in the knee. Methods: Thirty patients were randomized at a ratio of two to one (two were treated with an autologous cartilage tissue implant [NeoCart] for each patient treated with microfracture) at the time of arthroscopic confirmation of an International Cartilage Repair Society (ICRS) grade-III lesion(s). Microfracture or cartilage biopsy was performed. NeoCart, produced by seeding a type-I collagen matrix scaffold with autogenous chondrocytes and bioreactor treatment, was implanted six weeks following arthroscopic cartilage biopsy. Standard evaluations were performed with validated clinical outcomes measures. Results: Three, six, twelve, and twenty-four-month data are reported. The mean duration of follow-up (and standard deviation) was 26 ± 2 months. There were twenty-one patients in the NeoCart group and nine in the microfracture group. The mean age (40 ± 9 years), body mass index (BMI) (28 ± 4 kg/m2), duration between the first symptoms and treatment (3 ± 5 years), and lesion size (287 ± 138 mm2 in the NeoCart group and 252 ± 135 mm2 in the microfracture group) were similar between the groups. Adverse event rates per procedure did not differ between the treatment arms. The scores on the Short Form-36 (SF-36), Knee Injury and Osteoarthritis Outcome Score (KOOS) activities of daily living (ADL) scale, and International Knee Documentation Committee (IKDC) form improved from baseline (p < 0.05) to two years postoperatively in both treatment groups. In the NeoCart group, improvement, compared with baseline, was significant (p < 0.05) for all measures at six, twelve, and twenty-four months. Improvement in the NeoCart group was significantly greater (p < 0.05) than that in the microfracture group for the KOOS pain score at six, twelve, and twenty-four months; the KOOS symptom score at six months; the IKDC, KOOS sports, and visual analog scale (VAS) pain scores at twelve and twenty-four months; and the KOOS quality of life (QOL) score at twenty-four months. Analysis of covariance (ANCOVA) at one year indicated that the change in the KOOS pain (p = 0.016) and IKDC (p = 0.028) scores from pretreatment levels favored the NeoCart group. Significantly more NeoCart-treated patients (p = 0.0125) had responded to therapy (were therapeutic responders) at six months (43% versus 25% in the microfracture group) and twelve months (76% versus 22% in the microfracture group). This trend continued, as the proportion of NeoCart-treated patients (fifteen of nineteen) who were therapeutic responders at twenty-four months was greater than the proportion of microfracture-treated participants (four of nine) who were therapeutic responders at that time. Conclusions: This randomized study suggests that the safety of autologous cartilage tissue implantation, with use of the NeoCart technique, is similar to that of microfracture surgery and is associated with greater clinical efficacy at two years after treatment. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.