The biomechanical behavior of healing canine radii and ribs.

An experimental study and accompanying theoretical study of the biomechanics of healing canine ribs and radii have been conducted. Biomechanical behavior of the healing bones was determined experimentally by whole bone structural tests in four point bending. The experimental results indicated that the non-weight-bearing ribs regained bending stiffness more rapidly than bending stiffness, while the weight-bearing radii regained bending stiffness more rapidly than bending strength. These differences were not found to correlate with differences in overall callus biochemistry, but physical examinations of the bone suggested that differences in callus morphological details between the two bone types might offer an explanation. Utilizing a theoretical model, a parameter study of the influence of callus geometry and morphology on bending behavior was conducted. The results of the parameter study demonstrate that the experimentally observed variations in the amount and distribution of callus materials and in bone geometry can produce the qualitative biomechanical differences measured experimentally. The results of the parameter study also demonstrate that bending stiffness must be used with caution as a healing criterion since it does not necessarily reflect structural strength.