Introduction The regeneration capacity of articular cartilage is very limited. Therefore, cartilage defects heal poorly and are known as prearthrotic lesions. Autologous Matrix-Induced Chondrogenesis (AMIC) is an innovative treatment concept for localized full-thickness cartilage defects. This technique combines the well-established microfracturing with a collagen I/III scaffold fixated by fibrin glue.

Methods Presented are medium-term results of two different prospective studies of patients treated with AMIC. Symptomatic full-thickness cartilage lesions (Outerbridge grade III or IV) were treated using AMIC (Chondro-Gide, Geistlich Pharma, Switzerland). Patients were initially evaluated by established knee scores (e.g. Lysholm score, IKDC score) and in selected cases by magnetic resonance imaging (MRI). Patients were re-evaluated up to 5 years after the initial procedure.

Results In total 84 patients could be followed up. The average age of patients was in both groups 37 years (16–61 years). The mean defect size was 3.4 cm² respectively 4.2 cm². The majority of patients were satisfied with the postoperative outcome, reporting a significant decrease of pain level. Significant improvement of the mean Lysholm score was observed as early as 1 year after AMIC and further increased values were noted up to two years postoperatively. MRI analysis showed moderate to complete filling with a normal to incidentally hyperintense signal in most cases.

Conclusion AMIC is an effective and safe method of treating symptomatic full-thickness chondral defects of the knee in appropriately selected cases. However, further studies with long-term follow-up are needed to determine whether the grafted area will maintain structural and functional integrity over time. Level of evidence: Prognostic study, Level IV.