Meniscal healing: a histological study in rabbits.

Repair of meniscal tears occurs best in the region of the capsular attachment. The further the tear from the site of capsular attachment, the less the vascularity, and healing becomes dubious. For an evaluation of healing in the poorly vascularised zone of the meniscus a histological study was performed in rabbits with standard longitudinal incisions in the posterior horn of the left medial menisci. In addition a biomechanical investigation of scar strength was performed. Three groups of animals were studied: group 1 were allowed to heal spontaneously, group 2 were sutured and group 3 were treated with fibrin glue. After 6 weeks, macroscopically, 4 out of the 10 menisci in groups 1 and 3 exhibited incomplete scar formation, whereas all menisci in group 2 looked well. This result fell short of statistical significance because 2 menisci in group 2 had to be excluded due to faulty localisation of the standard injury. In all groups the scars contained fundamental elements of healing, such as fibroblasts, blood vessels and fibrous material. Repair seemed to be significantly influenced by the proliferating synovial membrane. Histologically there was no difference between group 1 and 3. In both groups the lesions were filled with a broad strip of reparative tissue mostly consisting of plexiform collagenous fibres. Although the appearance of the menisci in group 2 was similar, the scar tissue was distinctly thinner due to the close adaptation of the wound margins, and the vascularity seemed better. In all specimens the tissue located towards the free rim of the meniscus showed signs of degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)