(Verbatim from Applicant): Spine fusion procedures restore mechanical stability to a spinal column affected by disease or trauma by mechanical integration of two or more vertebrae. Failure to fuse the vertebra, pseudarthrosis, causes post operative pain and complications. On average, the accuracy of non-invasive imaging techniques in diagnosis of spinal pseudarthrosis is in the range of 59 percent to 80 percent. Currently, direct surgical exploration is the only 100 percent reliable fusion-diagnostic method. However, the bending moment carried by the spinal fixation instrumentation during simple flexion-extension tests depends on the stiffness of the fused spine elements. Therefore, by measuring strain in the elements of the spine fixating instrument, the quality of spine fusion can be evaluated as poor fusion transfers measurable strain onto the fixating device whereas full fusion bears most the load and only minor load transfer occurs. To evaluate status of spinal fusion we propose a telemetric, implantable device that consists of: (1) strain gauge sensor attached to the orthopeadic spine fixator; a device routinely implanted during surgery, and (2) passive electronic circuit (no """"""""on board"""""""" power source required) for measurement and wireless data transmission to an outside reader. This diagnostic device utilizes established technologies for new applications producing reliable and accurate diagnosis.
Over 247,000 fusions and 275,000 discectomies is performed in U.S. each year. Worldwide, the numbers are more than double Market growth for devices used in spine surgery has been estimated at more than 20%, while the growth rate for spine fusion procedures has been estimated at more than 10%. The worldwide spinal fixation devices market reached an estimated $1.1 billion in 1999 and is growing at approximately 15% per year. The designed sensor will result in significant reduction of cost of post surgical follow-ups. Improvement in patient treatment and the reduction of cost will be the major consequences of thisinnovation in spine fusion monitoring.
