FRACTURE STRENGTH PREDICTION IN RAT FEMORAL-SHAFT AND NECK BY SINGLE-PHOTON ABSORPTIOMETRY OF THE FEMORAL-SHAFT

The bone mineral content (BMC) and bone mineral density (BMD) of the f emoral midshaft from 15 skeletally mature male rats were measured by S ingle Photon Absorptiometry (SPA), and comparisons made to fracture st rength of the femoral diaphysis and the femoral neck. In stepwise regr ession the factors contributing significantly to the ultimate bending moment of the shaft were BMC and femoral length. BMC correlated strong ly with the ultimate bending moment of the femoral diaphysis (r(2) = 0 .63, P < 0.01). The correlation between BMC and ultimate moment of the femoral neck was moderate (r(2) = 0.51, P < 0.01). The correlations b etween BMD and mechanical parameters were lower than the corresponding values for BMC, with a significant result only for the bending moment of the femoral diaphysis (r(2) = 0.48, P < 0.01). In conclusion, BMC rather than BMD, is most predictive for fracture strength of the femur in rats.