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We are developing a transmission-based probe for point-of-care assessment of vertebrae strength needed for fabricating the instrumentation used in supporting the spinal column during spinal fusion surgery. The device is based on a transmission probe whereby thin coaxial probes are inserted into the small canals through the pedicles and into the vertebrae, and a broad band signal is transmitted from one probe to the other across the bone tissue. Simultaneously, a machine vision scheme has been developed to measure the separation distance between the probe tips while they are inserted into the vertebrae. The latter technique includes a small camera mounted to the handle of one probe and associated fiducials printed on the other. Machine vision techniques make it possible to track the location of the fiducial-based probe tip and compare it to the fixed coordinate location of the camera-based probe tip. The combination of the two methods allows for straightforward calculation of tissue characteristics by exploiting the antenna far field approximation. Validation tests of the two concepts are presented as a precursor to clinical prototype development.

We are developing a new transmission-based probe for assessing vertebrae strength via the differences between the dielectric properties of normal and osteoporotic bone. The probes are simple open-ended coaxial cables that will fit easily into the pedicle canals drilled by the surgeons before implanting screws to secure the supporting instrumentation. If the screws pull because of bone weakness, it can inflict a wide range of complications. In the progression towards actual clinical trials, we have already validated the approach on different liquids with varying dielectric properties. In this study, we assess actual animal bone samples as a precursor to human investigations. We exploit the fact that the trabecular bone is considerably different on opposite sides of the growth plate of long bones such as the femur - somewhat mimicking differences between normal and osteoporotic bone. For these experiments, we show that the properties of the distal and proximal sections are considerably different and present opportunities to exploit them in a diagnostic setting