Autologous Matrix-Induced Chondrogenesis (AMIC) and Microfractures for Focal Chondral Defects of the Knee: A Medium-Term Comparative Study

The potential of autologous matrix-induced chondrogenesis (AMIC) to restore unipolar focal chondral defects of the knee is promising. However, the outcome compared to microfracturing (MFx) for certain defect sizes (2-3 cm ) is still uncertain. Therefore, the present study compared primary isolated AMIC versus MFx in a cohort of patients with borderline sized focal unipolar chondral defects of the knee at midterm follow-up. Patients with chondral defects of the knee who underwent AMIC or MFx were compared. An arthroscopic approach was used for MFx, and a minimally invasive parapatellar arthrotomy for AMIC. For those patients who underwent AMIC, a collagen membrane was used with fibrin glue. The patients answered independently: Visual Analogic Scale (VAS), Tegner Activity Scale, International Knee Documentation Committee (IKDC), and the Lysholm scores. A total of 83 patients with a mean age of 30.2 and body mass index (BMI) of 26.9 kg/m were recruited. Of them, 33.7% (28 of 83) were women, and 55.4% (46 of 83 patients) had defects in the right knee. The mean length of symptoms before surgery was 43.3 months. The mean size of the defect was 2.7 cm . The mean length of follow-up was 42.1 months. No difference was found in terms of symptoms and follow-up length, mean age and BMI, mean size of defect, sex, and side. The AMIC cohort reported greater IKCD ( > 0.0001), Lysholm ( = 0.002), VAS ( = 0.01), Tegner ( = 0.004) scores. The AMIC cohort reported lower rate of failure ( = 0.005) and revision surgery ( = 0.02). No difference was found in the rate of arthroplasty ( = 0.2). No delamination or hypertrophy were detected. AMIC demonstrated superiority over MFx for focal unipolar chondral defects of the knee. At approximately 40 months follow-up, the IKDC, Lysholm, and VAS scores were greater in the AMIC group. Patients treated with AMIC also demonstrated a higher level of sport activity, and lower rates of failure and revision surgeries.