[Effect of absorbable poly-DL-lactide rods on experimental fracture healing]

This study was designed to assess the effect of a home-bred poly-DL-lactide (PDLLA) rods on experimental fracture healing. An operation was performed to create bilateral ulnar and radial fractures of forearm in 15 rabbits. The right sides were fixed with 2 PDLLA (Mv = 34 x 10(4), 1.6 mm x 1.6 mm x 30 mm) rods, and the contralateral sides were fixed with 2 Kirschner wires to be used as controls. After operation, casts were used for external fixation, and the joint above and the joint below the fracture were immobilized. The casts were removed at the 6th week after operation. The specimens were removed at specific intervals between 2 and 12 weeks. Histologically, the light microscopy and scanning electron microscopy evaluation of the rabbit ulnar and radial fractures fixation revealed that, the fractured bone gradually healed and the PDLLA rods properly fixed on the fracture area during the implanted period. However, results suggest that internal fixation by absorbable material made the course of fracture healing slower than that in the control group, but the osteogenesis appeared to be normal. In the absorbable group, the collagenous fiber was characterized by order and orientation, and calcified normally. In conclusion, this kind of PDLLA rods have an effect on delaying the process of the normal union of fracture and should be applicable to fractures where the tissues are rich in blood supply.