[Two-Year Results of Modified AMIC Technique for Treatment of Cartilage Defects of the Knee]

PURPOSE OF THE STUDY Damage to hyaline cartilage represents a serious problem due to its limited capacity of regeneration. Currently, there are several treatment options available. The purpose of this study is to evaluate the success rate of treatment of chondral and osteochondral defects of the knee joint using the modified AMIC (Autologous Matrix-Induced Chondrogenesis) technique, combining microfractures of the base and the implantation of the type I collagen-based cell-free implant over a two-year period. MATERIAL AND METHODS The prospective study of the success rate of treatment by the modified AMIC technique included 15 patients (13 men and 2 women) with a defect confirmed by MRI and appropriate indication criteria. The mean age at the time of implantation was 33.4 years (range 19-47 years). The mean size of a treated defect was 3.66 ± 1.71 cm2 (range 2.00-7.05 cm2). The clinical outcomes were monitored through the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Lysholm score and the Tegner activity scale preoperatively and subsequently at 6, 12 and 24 months postoperatively. Control MRI was conducted at 6, 12 and 18 months postoperatively. The MRI finding was evaluated using the Magnetic Observation of Cartilage Repair Tissue (MOCART) score. RESULTS The total KOOS score was 44.69 ± 7.71 preoperatively, while postoperatively it gradually increased up to 80.45 ± 8.97 (p < 0.001) at 24 months. The Lysholm score significantly rise from 43.47 ± 11.87 preoperatively to the mean value of 81.60 ± 13.07 (p < 0.001) at 24 months postoperatively. The preoperative Tegner score was 3.53 ± 1.41. At 24 months, there was a statistically significant increase to 5.40 ± 1.70 (p = 0.003). The mean MOCART score at 18 months postoperatively was 74.67 ± 14.08. At the end of the monitored period, a complete filling of the defect site by tissue was achieved in 73.33% patients. A complete integration with adjacent cartilage was seen in 66.67% patients and homogenous structure of newly formed tissue was reported in 80% of patients. DISCUSSION In recent years, cell-free implants (the so-called scaffolds or carriers) have been used ever more frequently in treating localised cartilage defects. Their main effect should consist in helping the cells penetrate the defect site and support new cartilage tissue formation. In order to improve the efficacy of cell-free implants, a new therapeutic technique was developed, combining the microfractures of the base with the use of cell-free scaffold AMIC (Autologous Matrix-Induced Chondrogenesis). Our modification of the original AMIC technique consists in the use of a type I collagen-based scaffold instead of the original collagen membrane constituted by collagen type I and III. Based on the statistical processing of results, the modified AMIC technique has shown a statistically significant improvement compared to the preoperative values of the KOOS questionnaire and all its sub-groups, the Lysholm core and the Tegner activity scale. These good clinical outcomes correlate with the results obtained by other authors using both the original method and the modified AMIC technique. CONCLUSIONS The modified AMIC technique using the cell-free type I collagen-based implant appears to be a safe, accessible and onestage technique to treat localised chondral and osteochondral defects of the knee joint up to the size of 8 cm2. Key words: hyaline cartilage, chondral defect, AMIC, scaffold, knee.