Design of a non-contacting electromagnetic device for measurement of the vibratory response of long bones

Development of non-invasive methods for quantitating the bone mass is important in the diagnosis and treatment of many skeletal diseases, particularly for osteoporosis. As standard roentgenographic methods can not detect early osteoporosis, presently quantitative computed tomography (QCT), and single, and dual photon absorptiometry (SPA and DPA) are being used to monitor the skeletal health of elderly population [1]. Although widely used clinically, these methods are relatively expensive and they involve some exposure to radiation. Previously we and others have used impact response of human long bone to measure the degree of osteoporosis and the rate of fracture healing [2,3]. However, skin-mounted accelerometer response as a parameter to measure in vivo bone condition is affected by the preload and condition of the soft tissue, thus affecting its use as a diagnostic tool. We have developed a non-contacting electromagnetic device that can detect the propagation of stress waves in a bone independent of the mechanical properties of the soft tissue. This device monitors the magnetic field produced by the strain-generated charge associated with a vibrating long bone [4]. The objective of this study was to characterize and improve the sensitivity of this device and to compare it with other methods as a diagnostic tool to measure the properties of long bone.