Comparison of the fixation of subcapital femoral neck osteotomies with absorbable self-reinforced poly-L-lactide lag-screws or metallic screws in sheep.

Seven subcapital femoral osteotomies of adult sheep were each fixed with two absorbable self-reinforced poly-L-lactide lag-screws, and seven other osteotomies were each fixed with two metallic cancellous bone screws. At 3 and 12 weeks, radiographs were taken and callus formation, displacement, and union were evaluated. At 12 weeks, the animals were killed and strength measurements were carried out. According to the radiographs, union was achieved in six of seven osteotomies in both groups, while after 3 weeks one fixation in both the group treated with absorbable screws and the group treated with metallic screws had failed. There were no statistical differences between the groups with respect to callus formation or displacement. Regarding the strength of the osteotomized bones, at 12 weeks there were no statistically significant differences in the load-carrying capacity between the bones fixed with self-reinforced poly-L-lactide screws and those fixed with metallic screws. These results showed that self-reinforced poly-L-lactide screws, which have been used successfully in fractures and osteotomies in cancellous bone, are strong enough to support this more demanding fixation of weight-bearing bones.