The purpose of this paper was to investigate whether the reflected synovio-capsular flap, covering one-third of the remaining peripheral after partial removal of two-thirds of the central medial meniscus of rabbit knee, contributes to the regeneration of meniscus.

Forty rabbits were used in this study. In each rabbit the right knee was used for the experimental group in which the synovio-capsular flap was reflected after a partial meniscectomy, while the left knee, with only a skin incision, was used for the control group. The width and thickness of the regenerated menisci were measured with the Vernier calliper, and evaluated grossly by Hematoxylin-Eosin (H-E) staining, histochemically by safranin-O staining, and subcellularly by transmission electron microscopy at 4, 8, 12 and 16 weeks after the operation.

The width and thickness of reflected synovio-capsular flaps gradually decreased until reaching a normal size. After eight weeks, there was no statistical difference between the experimental and control group. Twelve weeks after the operation, immature fibrocartilage cells appeared in the central portion of the reflected synovio-capsular flaps in 7 out of 8 rabbit knees. Sixteen weeks after the operation, more mature cartilage cells and their halos, stained very deeply with safranin-O, appeared in 6 out of 8 rabbit knees. In electron microscopic examination of cell shape, normal cell process and nuclear shape were observed with the passage of time. Rough endoplasmic reticulum and chromatin transparence peaked at 12 weeks and gradually returned to normal shape at 16 weeks.

The results showed that the reflected synovio-capsular flap in rabbit was incorporated with the remaining peripheral portion of the meniscus and became a normal meniscus-like structure.