[Experimental study on healing of old tear in the avascular portion of menisci in dogs].

32 adult mongrel dogs (male 14, female 18, average weight 16.7 kg) were used to study the healing process of old tear in the avascular portion of the menisci. They were divided into two groups--Control group and repair group which were divided into two subgroups, that is, debrided and undebrided groups. Dogs were sacrificed 2.4 weeks and 4.5 months and one year after repair respectively. Finally results were analysed by means of light and electron microscopy. The following conclusions were drawn: (1) A meniscal tear in the avascular portion would not heal by itself despite some cellular response on the edge of the tear. (2) Tear would not heal after simple vascular access channel procedure. (3)Tear healed with fibrocartilage when vascular access channel with synovial flap implantation was used. Therefore this technique can be considered as an alternative to meniscectomy in the management of torn meniscus clinically. (4) Debridement has a bad effect on the healing process because it makes the tear wider and longer and remove the activated cells. (5) The vascular access channel about one half of the thickness of the peripheral edge of the meniscus does not change the shape of the meniscus.