Tensile properties and biological response of poly(L-lactic acid) felt graft: an experimental trial for rotator-cuff reconstruction

Abstract

Poly(L-lactic acid) felt (PLLA felt) was prepared for reconstruction of the rotator cuff in animal models. Small changes were found in the tensile strength of both the cultured PLLA felt and the PLLA felt implanted on the paravertebral muscle of rabbits up to 16 postoperative weeks. The stiffness of the felt implanted on the muscle from 6 to 16 weeks showed a statistically significant increase. When the infraspinatus tendons of beagle dog were reconstructed with the PLLA felt, the ultimate strength of PLLA felt increased threefold, and the stiffness increased fivefold by 16 postoperative weeks compared to that of the initial PLLA felt. They were statistically significant (p < 0.01). All the implanted specimens ruptured at the junction between the bone and the PLLA felt. Histological examination demonstrated infiltration of fibrous tissue into the interstices of the PLLA felt fibers. Connection between the infraspinatus tendon and the PLLA felt was tight with the formed scar tissue, but the connective tissue between the bone and PLLA felt fibers was sparse even at 16 and 32 postoperative weeks. A few deteriorated PLLA felt fibers were observed at 32 postoperative weeks. It was concluded that the degradation rate of PLLA felt was low and the tensile recovery of the PLLA felt graft in beagle dogs was excellent. Thus, PLLA felt might be a useful bioabsorbable material for rotator-cuff reconstruction.