RESUMO
The creation of ridges of the deep surface of plates used for osteosynthesis increases their adherence to bone. By increasing the coefficient of friction between the plate and the bone, the stresses taken by the screws can be diminished by a third. The procedures diminishes by the same amount the risk of stripping or loosening of screws and thus the risk of pseudarthrosis. Experimental study has been made by measurement with the aid of an elliptometer and modifications in the state of polarization of a Lawer beam under the influence of shearing strains. The strains were those imposed on screws in Araldite fixing a plate whose inferior surface was smooth on one end and ridged on the other. The ridges should not be such as to prevent the later removal of the plate. Screws should be applied for preference with a dynamometric screwdriver because the stress relief is maximal with a tightening force of 12 inch pounds.
