Fixation of femoral shaft osteotomy with intramedullary metallic or absorbable rod: an experimental study on growing dogs.

The purpose of this study was to examine the effects of an intramedullary self-reinforced polyglycolic acid (SR-PGA), self-reinforced poly-L-lactic acid (SR-PLLA) and a metallic rod on growing bone and their applicability in the fixation of a femoral shaft osteotomy in growing dogs. In 5 dogs, 12 weeks of age, a SR-PGA rod and in another 5 dogs a SR-PLLA rod, both 4.7 mm in diameter and 60 mm in length, were introduced into the intramedullary cavity of the right femur to fix a femoral shaft osteotomy. In a third group of 5 dogs the femoral shaft osteotomy was fixed with an intramedullary metallic rod of equal size. The follow-up intervals were 1, 3, 6, 12, 24 and 48 weeks. Solid union of the osteotomy without secondary displacement was seen radiographically 6 weeks after the operation in all dogs. Neither an intramedullary SR-PGA-, SR-PLLA- nor metallic rod caused any significant disturbance to the longitudinal growth of the operated femur. Narrowing of the femoral neck and a slight valgization of the angle between the femoral neck and shaft without any functional disability was seen 48 weeks after the operation.