Early effects of the self-reinforced PGA implant on a growing bone: an experimental study on growing rats

The purpose of the study was to investigate the immediate/early effects of a bioabsorbable implant on a growing bone and monitor the strength retention. Fifty-eight rats were used as experimental animals. In 29 animals a 1.1 mm self-reinforced (SR-PGA) polyglycolic acid implant was placed through a transphyseal drill channel up to the diaphysis of the femur. In another 29 rats similar implants were placed in both femora and in the dorsal subcutis. After a follow-up time of 1-28 days a histologic and a roentgenographic analysis of the femora was undertaken and the shear and bending strengths of the removed implants in the other group were measured. The implant was broken at the plane of the growth plate by 21 days. No permanent growth disturbance occurred in the operated femora compared to the control side. The SR-PGA implants lost a substantial part of their mechanical strength in 2 weeks.