Influence of a rigid plate for internal fixation on the maximum torque capacity of long bones

The unfavourable effect of the rigid internal fixation plate on the strength (measured as maximum torque capacity) of the diaphyseal bone, with due attention to the importance of the screw holes, has been studied on the femora of 7 dogs. When the plates that had been applied for 7 months without previous osteotomy were removed, a significantly reduced maximum torque capacity was observed, as also a significantly reduced maximum angle of torsion, and a significantly changed distribution of the amount of bone mineral.