Intraoperative evaluation of bone decompression in anterior cervical spine surgery by three-dimensional fluoroscopy.

Sufficient bone decompression of osteophytes is essential for functional long-term outcome in surgery for spondylotic cervical myelopathy. Postoperative CT scans clearly show that decompression is sometimes insufficient. Intraoperative CT scanning has been used to monitor sufficient decompression. Instead of standard intraoperative fluoroscopy, we used an isocentered three-dimensional (3D) fluoroscopy with 3D image reconstruction to evaluate the extent of bone decompression. From October 2003 to April 2004, we have used intraoperative 3D fluoroscopy on seven patients with anterior cervical spine surgery due to cervical spondylotic myelopathy. Five patients were operated on in one level, two patients had surgery in two segments. If surgery was performed in two levels or preoperative cinetic MRT showed cervical instability, internal plate fixation was done additionally. All patients were positioned on a radiolucent operating table, made of carbon fibers. Three-dimensional fluoroscopy was always performed before wound closure to evaluate sufficient bone removal. The scanning time was 120 s and the whole procedure from scanning to evaluation is approximately 5 min. In all patients we were able to evaluate the extent of bone decompression. Additionally, placement of cage, plates and screws can be evaluated intraoperatively. In one patient, 3D fluoroscopy showed insufficient decompression, especially on the right side. Further bone removal was performed before the end of the procedure. Intraoperative 3D fluoroscopy is a valuable tool for imaging bone decompression and implant location in anterior cervical spine surgery. The technique is safe, reliable and should help us to avoid incomplete decompression or misplacement of implants and therefore improve long-term functional outcome in cervical spine surgery in the future.