Session IX - Spine

·Safety of Thoracic Pedicle Screw Instrumentation for the Treatment of Traumatic Spinal Instability

Carlo Bellabarba, MD; Jason H. Thompson, MD; Richard Bransford, MD; M. Bradford Henley, MD, MBA; Sohail K. Mirza, MD; Jens R. Chapman, MD; University of Washington, Harborview Medical Center, Seattle, Washington, USA

Purpose: Of the techniques available for posterior spinal fixation, pedicle screw instrumentation has been accepted as superior and more versatile in the treatment of lumbar spinal pathologic conditions. Many recognized advantages of pedicle screw systems are also applicable to their use in the thoracic spine. However, because of the smaller pedicle size and the potential dangers posed by the proximity of the spinal cord, great vessels, esophagus, and pleura to the thoracic vertebrae, the use of pedicle screws in the thoracic spine has not gained widespread acceptance. These same safety concerns have lead to the promotion of expensive and complicated three-dimensional intraoperative imaging techniques as a potential means for improving the accuracy of screw positioning. The purpose of this study was to determine the incidence of major complications associated with thoracic pedicle screw placement by using anatomic landmarks and intraoperative fluoroscopy in patients with traumatic spinal instability.

Methods: Retrospective review was conducted of 245 consecutive patients with spine injuries treated at a level-1 trauma center between 1995 and 2001 with pedicle screws placed between T1 and T10. The rate of major intraoperative and early postoperative complications was recorded. A major complication was defined as follows: potentially catastrophic vascular injury requiring immediate attention (aortic or azygous perforation), neurologic deterioration, pleural penetration resulting in pneumothorax or hemothorax, and esophageal injury. Patients were monitored for these complications from the time of surgery until discharge, which averaged 8 days (range, 3 to 24).

Results: A total of 1533 pedicle screws, ranging from 4.0 to 7.0 mm in diameter, were placed in 245 patients. Screws were placed from the T1 through T10 levels in the following respective quantities: 123, 108, 110, 129, 136, 160, 188, 166, 177, and 236. No patient sustained a neurologic injury, vascular injury, hemothorax, pneumothorax, or esophageal injury. Three patients (1.2%) required an unanticipated secondary procedure for prophylactic revision of 4 (0.26%) malpositioned screws (2 medial, 2 lateral). Two screws (0.13%) were placed at the incorrect level in one patient.

Discussion and Conclusions: The use of pedicle screw fixation has been shown to be biomechanically superior to alternative posterior stabilization constructs, allowing shorter segment fixation and increased fusion rates. Previously reported major complications specific to anatomic structures proximate to the thoracic vertebrae have discouraged the use of pedicle screw fixation at levels other than the thoracolumbar junction. Reports of complications have led to the development of intricate, expensive, and time-consuming intraoperative image guidance systems with as yet unproven accuracy. The results of this study support the use of pedicle screws in the thoracic spine with minimal complication rates in the hands of experienced surgeons using careful preoperative imaging evaluation, standard posterior element landmarks, and intraoperative fluoroscopy.

· The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an "off label" use).