Collagen Meniscus Implant. Clinical, radiological and magnetic resonance imaging results at 5 years follow-up

Surgical removal of meniscal tissue can result in pain, loss of joint stability, dysfunction of mechanical forces and can lead to osteoarthritis and irreversible joint damage. Therefore, meniscus tissue should be preserved whenever possible. In case of massive loss of meniscus tissue there are two applicable methods for substitution: allograft transplantation or implant of a collagen meniscus scaffold. In 1992 Stone, Steadman and Rodkey have developed a bioreadsorbable collagen matrix (CMI) (Regen biologics, Inc.,Franklin Lakes NJ, USA) which acts as a scaffold to replace the original medial meniscus. This scaffold supports ingrowth of new tissue by means of migration of fibrochondrocytes and the production of extracellular matrix and should supports regeneration of meniscal like tissue. Between January 2001 to December 2003, 34 patients underwent arthroscopic placement of a collagen meniscus implant by a single surgeon to treat an irreparably damaged medial meniscus. In 6 cases the patients had one prior meniscectomies. The others presented an irreparable meniscali lesion at time of surgery. Followup evaluation included Lysholm II Score and Tegner Activity Score, X-rays and MR-arthrography of the knee at 2 and 5 years after surgery. 6 patients were lost at follow-up: five didn’t accept intrarticular injection of contrast fluid and one patient had a new trauma of the knee that caused CMI failure. Lysholm scores improved significantly from 58 preoperatively to 94 at two years of follow-up. Average Tegner activity scores improved significantly from 2 preoperatively to 5 at 2 years. These results has been confirmed with clinical examination at 5 years with comparable scores. On standard X-rays there weren’t further degenerative changes of medial compartment compared to preoerative studies. On Mr-arthrography at 2 and 5 years CMI-meniscus complex was always visible even if in 17 and 20 cases respectively smaller in size compared to a normal medial meniscus. MR signal had continued to mature between 2 years and 5 years after implant, progressively decreasing intensity but in any case comparable to the low signal of a normal meniscus. The chondral surfaces of the medial compartment had not degenerated further since the placement of the implant. In six cases arthroscopic second look evaluation has been performed, revealing in all cases the presence of the implant, although with a reduced size respect to the original one. This population of patients showed very good clinical results after 5 years from a CMI arthroscopic implant. In most of cases CMI had a slightly reduction in size but, beside the CMI-meniscus complex presented abnormalities in aspect if compared with a normal medial meniscus, has helped reduce the deterioration by protecting the chondral surfaces in all patients at five years of follow-up.