NATURAL HEALING OF ANTERIOR AND POSTERIOR ATTACHMENTS OF THE RABBIT MENISCUS

The natural healing capacity of the anterior or posterior medial menis cal attachment after radial transection and the effect of such procedu res on knee joint cartilage were investigated in 28 skeletally mature New Zealand white rabbits, Either the anterior (n = 14) or the posteri or attachment (n = 14) was radially transected in the right knee joint , Fifty percent of the rabbits with each procedure were euthanized at 6 weeks and 50% at 12 weeks. The histologic characteristics of the hea ling tissue were evaluated, including immunohistochemical demonstratio n of nerve fibers, Histologic changes in the synovium and articular ca rtilage were graded for severity and extent, The concentration of prot eoglycan fragments in joint fluid was analyzed before operation and at euthanasia, After both procedures, the transected attachment healed i n a prolongated position resulting in peripheral displacement of the m eniscus. The healing tissue at 6 weeks was composed mainly of granular tissue, By 12 weeks, the healing tissue at the anterior attachment ha d a ligament like structure, but at the posterior attachment, fibrocar tilage like tissue had formed, Nerve fibers were found in the healing tissue, but connections to nerves in normal attachment or meniscal tis sues were not found, Increased concentrations of proteoglycan fragment s, articular cartilage degeneration, and synovitis were found in the o perated knees, These data indicate that although the meniscal attachme nt can heal in a prolongated position, such a meniscus has lost its me chanical functions, Further, a joint protective function of the neoneu rons is doubtful because of the lack of continuity with the adjacent m eniscus, Rigid fixation of the attachment seems essential for a functi onal meniscal substitute.