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To the Editor:—
Drs. Pentecost, Murray, and Brindley are to be congratulated for systematizing a puzzling group of fractures ("Fatigue, Insufficiency, and Pathological Fractures," JAMA187:1001 [March 28] 1964).We wish to comment on the use of engineering terminology to explain the mechanical behavior of bone. Stress is the internal force per unit area that one face of an internal plane of a body exerts on the other face, and is measured in pounds per square inch or kilograms per square millimeter. The magnitude and direction must also be given. Strain is the change in shape of a body due to applied loads or temperature variation. Elasticity is the ability of the body to return to its original shape immediately after the removal of external loads. If stress is plotted against strain, a straight line will result for a linearly elastic body.Stress, strain, and load cannot be used
Frankel VH, Berstein A. Use of Engineering Terms in Bone Disease. JAMA. 1964;189(3):242. doi:10.1001/jama.1964.03070030064030