Background: The use of autologous chondrocyte implantation (ACI) remains limited, even though multiple studies have demonstrated success rates exceeding 75%. The procedure is perceived as invasive and technically challenging, presenting barriers to more widespread adoption. Purpose/Hypothesis: The objective of this study was to investigate whether outcomes and the failure rate of a simplified ACI technique (cs-ACI) were comparable with those of the more complicated traditional technique of a chondrocyte suspension injected under a collagen membrane (cACI). We hypothesized that the change in technique would not negatively affect outcomes.
Study design: Cohort study; Level of evidence, 3.
Methods: Thirty-nine patients treated with the cs-ACI technique fulfilled the inclusion requirements. A group of 45 patients treated previously with standard cACI was used as a comparison. The functional outcomes were prospectively collected both preoperatively and postoperatively at the last follow-up. Failure was defined as any graft removal of more than 25% of the original defect size. Magnetic resonance imaging was performed postoperatively, and scans were assessed using a modified MOCART (magnetic resonance observation of cartilage repair tissue) scoring system.
Results: Group demographics were not significantly different, except for the defect size and mean follow-up: 4.09 years in the cACI group and 2.46 years in the cs-ACI group. Significant improvements were seen in all outcome measures except the Tegner score from the preoperative baseline to the latest follow-up for both the cACI group (International Knee Documentation Committee [IKDC] score, from 42.0 to 63.4; Knee injury and Osteoarthritis Outcome Score [KOOS]-Pain subscore, from 58.7 to 77.1; Lysholm score, from 57.2 to 69.7; and Tegner score, from 3.5 to 4.2) and the cs-ACI group (IKDC score, from 45.6 to 68.0; KOOS-Pain subscore, from 66.6 to 84.7; Lysholm score, from 53.7 to 75.4; and Tegner score, from 3.2 to 3.8). No significant difference was found between the groups at the latest follow-up. The failure rate at 2 years was not significantly different, while the total failure rate over the entire study period was significantly lower in the cs-ACI group than the cACI group (5% vs 24%, respectively). The overall MOCART score was not significantly different between the groups.
Conclusion: The treatment of full-thickness articular cartilage defects with a simplified cell-seeded ACI technique demonstrated no significant differences in the failure rate and patient-reported outcomes when compared with a standard technique utilizing interrupted sutures and the injection of a cell suspension under a collagen membrane.
Keywords: ACI; cartilage repair; chondrocyte; collagen membrane.