INFLUENCE OF THE OPERATIVE TECHNIQUE ON M ENISCUS TRANSPLANTS AN EXPERIMENTAL INVESTIGATION

After transplantation, a meniscus undergoes alterations in mechanical loading, which causes changes in its histological structure. We studie d the degenerative effects on meniscus and tibial cartilage resulting from variations in the congruity or the isometric fixation of medial m eniscus transplants. In th ree groups of five sheep each, the menisci were transplanted in three different ways, using the same operative ap proach. The menisci were evaluated 24 weeks after operation. In group 1, the meniscus was totally detached from its base at the capsule and refixed without changes in the congruity or isometry. This group provi ded the basic data. In group 2, the contralateral medial meniscus was turned upside down and transplanted. The reattachment was performed ac cording to isometric conditions. With this technique the congruity of the tibial and femoral surface was modified. In group 3, the medial me niscus was reimplanted by choosing defined non-isometric Fixation poin ts for the anterior and posterial meniscal ligaments without changing the position of the corpus. For evaluation,the morphological alteratio ns of meniscus and tibial cartilage were asessed by the Jackson score. The more distinct changes of the meniscus were assessed histologicall y by three criteria:surface cells, surface fibers and changes in the m eniscus center. The highest degree of degenerative changes occurred in group 3 (score 4.5); however, considerable changes were also found in group 2 (score 3.5). Incongruous or non-isometric placement of a meni scal graft will lead to degeneration and failure of the graft.