Short- to Midterm Clinical Outcomes After Autologous Minced Cartilage Implantation for Focal Chondral Defects of the Knee Are Comparable to Microfracture and Autologous Chondrocyte Implantation: A Systematic Review.

Abstract

To evaluate the safety and efficacy of autologous minced cartilage implantation (AMCI) compared with microfracture (MFX) and autologous chondrocyte implantation (ACI)/matrix-assisted ACI (MACI). Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed, Embase, and Cochrane databases were queried in May 2025. Inclusion criteria were Level I to IV human studies published between 2015 and 2025 with ≥12-month follow-up and reporting ≥2 validated clinical outcomes. Analysis of patient cohorts was performed using forest plots to make qualitative assessments, whereas descriptive statistics and ranges were used to report quantitative data to avoid heterogeneous pooling. A total of 41 studies (2116 patients) were included. Of these, 1590 underwent ACI/MACI, 302 MFX, and 224 AMCI. The mean patient age was 34.4 years for ACI/MACI, 45.0 years for MFX, and 32.7 years for AMCI. The mean follow-up was 61.1 months for ACI/MACI, 58.6 months for MFX, and 29.3 months for AMCI. Overall, there were no significant differences between International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score subscores, Lysholm, Tegner, and Visual Analog Scale pain at postoperative follow-up after ACI, MACI, MFX, and AMCI. Most relevantly, there was no significant difference between International Knee Documentation Committee for ACI (50.91-92.70), MACI (34.18-89.57), MFX (37.63-79.53), and AMCI (56.97-87.29). Qualitative analysis suggests that failure was lowest in AMCI (0%) compared with MFX (1.32%) and ACI/MACI (3.21%), and reoperation rates were variably reported but tended to be lower in AMCI and MFX (n = 10 and n = 14, respectively) compared with ACI/MACI (n = 155). AMCI shows clinical outcomes that are at least comparable to ACI, MACI, and MFX and may be an appropriate alternative treatment for focal chondral defects of the knee. However, available studies are heterogeneous, and long-term data for AMCI remain limited. Level IV, systematic review of Level I to IV studies.