Use of MACI (Autologous Cultured Chondrocytes on Porcine Collagen Membrane) in the United States: Expanded Experience over 5,000 Cases

ObjectiveTo determine whether there are differences in MACI (matrix-induced autologous chondrocyte implantation) treatment in the United States, by comparing cartilage defects and patient characteristics between the initial 1,000 patients treated with the next 5,000MethodsFollowing initial analysis of the first 1,000 consecutive patients treated with MACI, data were collected and analyzed for the subsequent 5,000. Patients were identified by MACI lot number and surgery date. Adverse events were summarized with descriptive statistics. Group differences were assessed with <i>t</i>-tests and chi-square, with significance set at <i>P</i> < 0.05.ResultsFive thousand adults (5,198 knees) were implanted with MACI by 1,130 surgeons. Patient sex (male 49.2%) was evenly split, and the mean age was 33.6 years. Most patients had a single cartilage defect treated, and the mean defect size was 4.4 cm². The patella was the most treated surface (38.4%), followed by the medial femoral condyle (25.7%). Most patients (85.5%) had concomitant surgical procedures at the time of cartilage biopsy procurement. There were statistically significant differences in the number of patella (<i>P</i> < 0.001), medial femoral condyle (<i>P</i> < 0.001), and "not specified" (<i>P</i> = 0.008) between groups. Mean defect size and mean total defect size were both larger (<i>P</i> < 0.001 and <i>P</i> = 0.009, respectively) in the subsequent 5,000 patients.ConclusionThe utilization of MACI has remained consistent. Patient demographics and concomitant surgical procedures between the first 1,000 MACI patients and subsequent 5,000 MACI patients were comparable. Patellofemoral defects were the most treated in both subsets, and an overall low rate of adverse events was observed.