MENISCAL REPAIR BY FIBROCARTILAGE IN THE DOG - CHARACTERIZATION OF THE REPAIR TISSUE AND THE ROLE OF VASCULARITY

Lesions in the avascular part of 20 canine menisci were repaired by im plantation of a porous polyurethane. Seven menisci were not repaired a nd served as controls. The repair tissue was characterized by biochemi cal and immunological analysis. The role of vascularity in healing was studied by perfusion of menisci with Indian ink. Histologically, repa ir tissue inside the implants initially consisted of fibrous tissue co ntaining type I collagen. After 2 months, fibrocartilaginous tissue de veloped inside the implants, whereas control defects only showed repai r with fibrous tissue. Both type I and type II collagen, the two major collagen types of normal meniscal fibrocartilage, could be detected i n this newly formed fibrocartilage. The implant guided vascular tissue from the periphery towards the lesion resulting in healing of the tea r. After fibrocartilage had formed, vascularity decreased and was comp letely absent in mature fibrocartilage. Control defects remained fille d with vascular connective tissue. Two-thirds of the longitudinal lesi ons were found to be healed partially or completely. It is concluded t hat implantation of a porous polymer does enhance vascularity sufficie ntly to result in healing of meniscal lesions extending into the avasc ular part. Healing takes place by repair tissue strongly resembling no rmal meniscal fibrocartilage. (C) 1996 Elsevier Science Limited