The development of an in vivo spinal fusion monitor using microelectromechanical (MEMS) technology to create implantable microsensors.

摘要

Surgical fusion of the spine is a conventional approach, and often last alternative, to the correction of a degenerative painful spinal segment. The procedure involves the surgical removal of the intervertebral disc at the problematic site, and the placement of a bone graft that is commonly harvested from the patient's iliac crest and placed within the discectomized space. The surrounding bone is expected to incorporate and remodel into the bone graft to eventually provide an immobilized site. Spinal instrumentation often accompanies the bone graft to provide further immobility to the targeted site, thus augmenting the fusion process. However, the status of a fusion and the incorporation of bone across a destabilized spinal segment are often difficult for the surgeon to assess. Radiographic methods provide static views of the fusion site that possess excessive limitations. The radiographic image cannot provide the surgeon with information regarding fusion integrity when the patient is mobile and the spine is exposed to multiple motions. Fortunately, technological advances utilizing microelectromechanical system technology (MEMS) have provided insight into the development of miniature devices that exhibit high resolution, electronic accuracy, miniature sizing, and have the capacity to monitor long-term, real-time in vivo pressures and forces for a variety of situations. However, numerous challenges exist with the utilization of MEMS devices for in vivo applications.;This work investigated the feasibility of utilizing implantable microsensors to monitor the pressure and force patterns of bone incorporation and healing of a spine fusion in vivo. The knowledge obtained from this series of feasibility test using commercially available transducers to monitor pressures and forces, will be applied towards the development of miniature sensors that utilize MEMS technology to monitor real-time, long-term spine fusion in living subjects. The packaging, and radiographic, and sterilization characteristics of MEMS sensors were evaluated for the future application of long-term human implantation for real-time, accurate measurement of the loads during bone healing.