Screw malpositioning or inadequate reduction detected on postoperative computed tomography may necessitate revision surgery. Intraoperative availability of computed tomography is low. Therefore, computed tomography is recommended to assess screw positioning and reduction. Even though the Gertzbein–Robbins classification facilitates the assessment of the screw position, the practical implementation in the operating room with the aid of conventional 2D fluoroscopy remains highly challenging or, in some cases, gives great residual uncertainty. At the same time, however, it must be taken into account that the thoracic pedicles are commonly < 4 mm wide, so that even thin pedicle screws can perforate the pedicle in this area. Deviations > 2 mm outside the pedicle are classified as type C according to Gertzbein–Robbins and are considered to need correction, even if no neurologic damage is to be expected with medial deviations up to 4 mm. developed their classification (A–E) of pedicle screw position. Ĭonsequently, it is necessary to check and assess the pedicle screw position intraoperatively, for which Gertzbein–Robbins et al. This is also very important if adjacent organs (e.g., aorta, vena cava, lung, trachea, esophagus, etc.) and blood vessels are present, which can be injured intraoperatively. Moreover, the screw tip should lie in the vertebral body, but without penetrating the ventral cortex. observed temporary neurologic impairment in 2.4% and persistent neurologic damage in 2.3% of their 617 surgically treated patients. Despite this anatomic proximity, injuries of these important nervous structures are rarely observed. While lateral malpositioning of the pedicle screw may affect the stability, medial perforation of the pedicle screw may be associated with severe neurologic impairment. Ideally, the screw should be centrally located in the pedicle without tangentially affecting or perforating the pedicle cortex. However, this is of particular importance due to the adjacent structures. Misplaced pedicle screws after dorsal instrumentation are observed in between 1.5 and 40% of cases in the current literature. One difficulty in inserting screws in the spine is their correct placement in the pedicle without perforating medially or laterally. The current gold standard for the surgical therapy of spinal fractures, in degenerative and in the majority of congenital diseases, is the dorsal instrumentation of the spine using pedicle screws. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. Misplacement of screws cannot always be prevented. This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C–E). In contrast, 384 (76.8%) screws in the CG were without relevant perforation (type A + B), of which 282 (56.4%) could be classified as type A and 102 (20.4%) as type B. Fifty-six (11.2%) screws in SG showed relevant perforation (type C–E). Postoperative computed tomography of the SG showed 445 (88.8%) screws without relevant perforation (type A + B), of which 410 (81.8%) could be classified as type A and 35 (7.0%) could be classified as type B. Resultsĭuring the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. Then, 500 screws in 82 patients (age 64.8 ± 14.4 a m/f 51/31) as control group (CG), who received the screws with conventional 2D fluoroscopy but without 3D imaging, were evaluated with regard to screw position. After this, 501 screws in 73 patients (age 62.5 ± 19.7 a m/f 47/26) of this collective were included in the study group (SG) and their postoperative computed tomography was evaluated with regard to screw position. This study first evaluates intraoperative imaging. Totally, 351 patients (age 60.9 ± 20.3 a (15–96) m/f 203/148) underwent dorsal instrumentation with intraoperative 3D imaging with 2215 pedicle screws at a trauma center level one. The hypotheses were that intraoperative 3D imaging (1) will lead to an intraoperative revision of pedicle screws and (2) may diminish the rate of perforated screws on postoperative imaging. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. Correct positioning of pedicle screws can be challenging.
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