Collagen Meniscus Implant (CMI): early clinical results and implant analysis

Aim: Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. We report clinical results achieved on 48 patients. The implant was also investigated by ultrastructural and biochemical analysis. Methods: Forty-eight patients, affected by irreparable meniscal lesions, were arthroscopically treated. Average age at the time of surgery was 38.4 years. The average size of the lesion/defect was 4.3 cm. Additional procedures included 16 ACL reconstruction, 8 high tibial osteotomy and 2 autologous chondrocyte implantation. All knees were evaluated according to the Lysholm II and Tegner activity scales. MRI was performed 6, 12 and 24 months postoperatively. A biopsy of the implant was performed in occasion of a second arthroscopic look in two patients 6 months after surgery. The specimens, as well as the scaffold before implantation, were studied by light microscopy, TEM, SEM, EDAX microanalysis and FACE analysis. Results: Follow up averaged 13.7 months. At 6 months, 44 patients showed an increase in the clinical scores. In the two second looks, the newly formed menisci appeared healed to the parameniscus and to the residual meniscal stumps. Good consistency and stability was detected by probing. A progressive uniform signal was evident by MRI. Morphological analysis of the speciments showed hyaline tissue infiltrated by cells and vessels, surrounded by the scaffold fibers. At EDAX microanalysis no calcifications were detected inside the speciments. Biochemical assays demonstrated the presence of GAG molecules of hyaluronic acid and chondroitinsulphate, that were not present in the scaffold before implantation. Conclusions: CMI results are promising and are supported by morphological and biochemical findings, that indicate enhancement of new meniscal tissue by the scaffold.