ANALYSIS OF INTRAOSSEOUS STRESS FIELD DUE TO COMPRESSION PLATING

Photoelastic methods, strain gages, and other techniques using plastic models and bone samples, with several available compression plates, are used in an attempt to establish a model for the determination of the intraosseous stress field created in a fractured long bone due to the installation of a compression plate. Analysis of this model shows that a superposition of compression and bending induced in the bone causes compaction of the bone ends over a small area of contact directly under the plate, and distraction of the bone ends away from the plate. It is found that at an axial load, in the plate, of 120 lb//f (534 N), a bending moment of about 90 in-lb//f (10 m-N) is applied to the bone. This results in a contact area of from 8 to 20 per cent of the area of the bone ends, on which the stress may be as high as 8400 psi (5. 8 multiplied by 10**7 N/m**2). No attempt is made to examine the biological effects of compression plates on fracture healing.