Solid mechanics and strength of bone in young dogs.

Fresh tibiae and femora from 22 harriers ranging in age from 8 to 44 weeks have been studied with a computerized torsion-machine. The growth of the dogs studied ceased at an age approaching 30 weeks. The strength and stiffness of the entire bones also ceased to increase at that age, and the increase in stress at fracture and shear modulus of the bone material strongly declined in impetus. This means that no important maturation, as measured in strength of the bone material, takes place after cessation of growth. The fracture twist angle per unit bone length was greatest for the younger bones and decreased to an age of around 25 weeks; the relation, however, between the linear and the non-linear part of the torque-twist curves did not change. Furthermore, the study indicates that juvenile bones, like adult bones, are essentially elastic-brittle, and there was no sign of increased plasticity in the young bones.