Failures, Reoperations, and Improvement in Knee Symptoms Following Matrix-Assisted Autologous Chondrocyte Transplantation: A Meta-Analysis of Prospective Comparative Trials

Objective: Though multiple high-level comparative studies have been performed for matrix-assisted autologous chondrocyte transplantation (MACT), quantitative reviews synthesizing best-available clinical evidence on the topic are lacking.

Design: A meta-analysis was performed of prospective randomized or nonrandomized comparative studies utilizing MACT. A total of 13 studies reporting 13 prospective trials (9 randomized, 5 nonrandomized) were included (658 total study participants at weighted mean 3.1 years follow-up, range 1-7.5 years).

Results: Reporting and methodological quality was moderate according to mean Coleman (59.4 SD 7.6), Delphi (3.0 SD 2.1), and MINORS (Methodological Index For Non-Randomized Studies) scores (20.2 SD 1.6). There was no evidence of small study or reporting bias. Effect sizes were not correlated with reporting quality, financial conflict of interest, sample size, year of publication, or length of follow-up (P > 0.05). Compared to microfracture, MACT had greater improvement in International Knee Documentation Committee (IKDC)-subjective and Knee Injury and Osteoarthritis Outcome Pain Subscale Score (KOOS)-pain scores in randomized studies (P < 0.05). Accelerated weight-bearing protocols (6 or 8 weeks) resulted in greater improvements in IKDC-subjective and KOOS-pain scores than standard protocols (8 or 11 weeks) for MACT in randomized studies (P < 0.05) with insufficient nonrandomized studies for pooled analysis.

Conclusions: Compared to microfracture, MACT has no increased risk of clinical failure and superior improvement in patient-reported outcome scores. Compared to MACT with standardized postoperative weight-bearing protocols, accelerated weight-bearing protocols have no increased risk of clinical failure and show superior improvement in patient-reported outcome scores. There is limited evidence regarding MACT compared to first-generation autologous chondrocyte implantation, mosaicplasty, and mesenchymal stem cell therapy without compelling differences in outcomes.