We hypothesized that a scaffold which is absorbable after the regeneration of damaged tissues and induce stem cells from surrounding tissues can repair massive rotor cuff tear without transplantation of stem cells. We prepared a bioabsorbable scaffold from synthetic poly(l-lactic acid) (PLLA) fibers and evaluated its use in the regeneration of rotator cuff tear in a rabbit model. The surface of the PLLA scaffold was kept smooth to prevent adhesion, and its inside was maintained rough to allow the surrounding cells to migrate and remain in the scaffold. It was transplanted under the back skin muscle of a rabbit, then histological examination was performed at 3weeks postoperatively. Scaffold was superimposed in double layers by keeping the smooth surface outside and the rough surface inside, and both edges of the double layered scaffolds were bonded by thermocompression. Double layered scaffolds were transplanted into infraspinatus defect models of rabbits. The implanted PLLA scaffolds were then evaluated mechanically and histologically at 2, 4, and 8 weeks postoperatively. In the back skin scaffold, fibrous tissue mainly existed in rough surface. In the shoulder scaffold, the PLLA scaffold persisted in the regenerated tissue, and the fibroblasts and macrophages were observed around the PLLA fibers. The scaffold did not absorb by 8weeks after the operation, and the enthesis of tendon was not regenerated by fibrocartilage, but fibrous tissue. The ultimate failure load of the PLLA scaffold was significantly increased and recovered to that of the normal tendon at 8 weeks. The stiffness was also increased, however there was no significant difference. The novel scaffold which has a smooth surface and rough inside can induce surrounding cells in its inside, and might regenerate the tendon tissue. Further study is required to improve the regeneration of the tendon tissue.
