ELECTROMECHANICAL PROPERTIES OF FRESH WHOLE BONE.

Abstract : Electromechanical properties of freshly excised rat femurs were studied by generation of electric potentials across the diaphysis after deformation of the bone by means of various (100-2,000 gm.) loads. The distal portion of the right femur was deformed from the long axis in posterior, anterior, lateral, and medial directions. With load application, concave areas became negatively charged and then discharged exponentially to near neutrality. A similar signal of opposite polarity ensued with load removal. Peak potentials with load application were 10% to 20% larger than those after load removal. Voltage output was related to load (posterior deformation) in a curvilinear manner, being proportional to lower loads and diminishing with the 2,000-gm. load. This decrease in voltage was associated with marked permanent deformation of the femur. Voltage and deformation caused by a 1,000-gm. load were significantly less after lateral or medial deflection than after posterior or anterior deflection. Results indicate that bone potentials are dependent upon deformation and may be related to the visco-elastic properties of bone. (Author)