OTA 1997 Posters - Spine Fractures

Ultrasound Guided Spinal Fracture Reposition including Color Coded Duplex Sonography of the Arteria Spinalis Anterior

Prof. Jürgen Degreif, MD, Lothar Rudig, MD, Martin Runkel, MD, Prof. Pol Maria Rommens, MD

Universität Mainz, Mainz, Germany

Purpose: In spinal fracture treatment the reduction of narrowing intra-canal fragments has to be discussed. Because of the disadvantages of the intraoperative myelography and avoiding a destabilizing laminectomy we use the intraoperative ultrasound (ATL 7.5 MHZ, sector) to judge the spinal canal. In the present paper the validity of the intraoperative ultrasound concerning fracture reposition should be shown. Beyond that, the possibilities of the color flow, duplex sonography can be shown in a few cases.

Materials and Methods: In our clinic the intraoperative spinal sonography (IOSS) was introduced in 1990 and applied in 61 cases so far. The transducer is always placed on a one-sided interlaminar fenestration at the level of the injured segment. In two cases there was no usable sonographic picture. In 59 cases the spinal canal and the fractured posterior surface of the vertebral body could be shown. In these 59 cases the initial intraoperative sonographical findings were compared with the preoperative CT-results concerning the mid-sagittal diameter of the spinal canal. The intraoperative sonographic results after reduction of the intracanal fragment were compared with the postoperative CT results. In 6 cases we additionally tried to visualize the arteria spinalis anterior by means of color-coded duplex sonography, using a special ultrasound equipment (7.5 MHZ electronic, lending instruments by ATL and Kretz company). All fractures were stabilized by the AO-fixateur interne (resp. USS).

Results: In all 59 cases we found an exact correspondence of the intraoperative sonographic findings after reduction with the postoperative CT results concerning the mid-sagittal diameter. Comparing the intraoperative ultrasound before instrumental reduction of the intracanal fragment with the preoperative CT, we found an exact correspondence only in 34 cases. In 25 cases the IOSS showed a larger mid-sagittal diameter than the preoperative CT. In 6 cases we were able to see the arteria spinalis anterior by color-coded duplex sonography. In 2 cases of occlusion of the vessel at the level of the intracanal fragment the reduction of the fragment resulted in recalibration of the artery.

Discussion: In the two unsuccessful attempts of IOSS the fractured posterior surface of the vertebrae were demolished severely, causing sonographical artifacts. In the 59 successful attempts the myelon and the width of the spinal canal could be judged exactly with an exact correspondence to the postoperative CT. Concerning the IOSS before instrumental reduction of the intracanal fragment we must have in mind, that this intraoperative investigation is performed after bringing the patient in prone position and lordosation. By doing so partial indirect reduction by ligamentotaxis is possible, producing also restoration of the spinal canal. Concerning the color-coded duplex findings we have to notice that the arteria spinalis anterior can be occluded in case of intra-canal fragment and can be recalibrated by instrumental reduction of the spinal stenosis. The incidence of neurologic failure depends on the plurisegmental or paucisegmental kind of blood supply of the spinal cord.

Conclusion: The intraoperative ultrasound enables a fast and complete intraoperative examination of the spinal canal and the posterior border of the vertebral body. The reduction can be controlled easily and repeatedly. The visualization of the arteria spinalis anterior by color-coded duplex sonography is possible, showing different findings before and after direct reduction of the intracanal fragment.