Intramedullary fixation of cortical bone osteotomies with absorbable self-reinforced fibrillated poly-96L/4D-lactide (SR-PLA96) rods in rabbits

Osteotomies of the femoral diaphysis were fixed with absorbable self-reinfo rced fibrillated poly-96L/4D-lactide (SR-PLA96) intramedullary rods (4.5 mm x 50-60 mm) in 43 adult rabbits. Follow-up times varied from 3 weeks to 3 yr. After sacrifice histological, oxytetracycline-fluorescence and microrad iographic studies of the bones were performed. Strength characteristics and changes in crystallinity and molecular weight of the rods were also measur ed, All osteotomies were evaluated radiographically, Thirty-six osteotomies (84%) healed uneventfully. The implant disappeared almost totally within 3 yr and histology showed only a minor foreign body reaction. From 6 weeks o n, the bending force needed to break the osteotomy was comparable to the be nding force needed to break the control bone. The shear strength of the rod s displayed only minor changes for the first 24 weeks. Subsequently, the ro ds rapidly lost their strength and at 48 weeks there was practically no she ar strength left, which is ideal for healing of an osteotomy. The present i nvestigation demonstrated, that absorbable, fibrillated SR-PLA96-rods can b e used for the intramedullar fixation of simple cortical bone osteotomies i n rabbits. These results have encouraged us to continue our studies with th e fixation of experimental cortical bone osteotomies in larger species. (C) 2000 Elsevier Science Ltd. All rights reserved.