Comparison of stainless steel and composite plates in the healing of diaphyseal osteotomies of the dog radius: report on a short term study.

The rigid fixation of fractures is generally accepted as the best method to achieve union when open treatment of a fracture is undertaken. This has led to the development of plates that have a greater overall dimension and stiffness compared to earlier plate models, as exemplified by the Lane or Eggers type of plate. In our experience the more rigid plate generally leads to satisfactory union, but also carries with it the risk of refracture, either through a screw hole or across the original fracture after plate removal. Experiments by Uhtoff and Dubuc on experimental animals showed that plate induced osteopenia existed when a rigid plate was applied to an intact or osteomized canine femur. These results provide a possible explanation for the occurrence of late fracture. The study to be described is based on the hypothesis that a rigid plate applied to bone induced localized immobilization osteopenia, which ultimately weakens the bone and leads to the development of late fracture. The study was designed to compare a plate made of stainless steel, which exhibited mechanical stiffness comparable to that of devices presently in use, with a plate made of a composite material, which exhibited decreased stiffness by nearly one order of magnitude. It had been demonstrated by engineering analysis that the less stiff plate would allow the bone to experience normal loading, and it was thought that this loading would modulate the rate and pattern of bone remodeling, thereby resulting in bone of greater strength and size as compared to a more rigidly plated bone.