Thoracic pedicle screws: postoperative computerized tomography scanning assessment

2004 ◽  
Vol 100 (4) ◽  
pp. 325-331 ◽  
Author(s):  
Robert F. Heary ◽  
Christopher M. Bono ◽  
Margaret Black
Keyword(s):  
Computerized Tomography ◽  
Pedicle Screws ◽  
Ct Scanning ◽  
Screw Placement ◽  
Grading System ◽  
Content Type ◽  
Thoracic Pedicle Screws ◽  
Grade Ii ◽  
Grade Iii ◽  
Fine Print

Object. The authors evaluated the accuracy of placement of thoracic pedicle screws by performing postoperative computerized tomography (CT) scanning. A grading system is presented by which screw placement is classified in relation to neurological, bone, and intrathoracic landmarks. Methods. One hundred eighty-five thoracic pedicle screws were implanted in 27 patients with the assistance of computer image guidance or fluoroscopy. Postoperative CT scanning was conducted to determine a grade for each screw: Grade I, entirely contained within pedicle; Grade II, violates lateral pedicle but screw tip entirely contained within the vertebral body (VB); Grade III, tip penetrates anterior or lateral VB; Grade IV, breaches medial or inferior pedicle; and Grade V, violates pedicle or VB and endangers spinal cord, nerve root, or great vessels and requires immediate revision. Based on anatomical morphometry, the spine was subdivided into upper (T1–2), middle (T3–6), and lower (T7–12) regions. Statistical analyses were performed to compare regions. The mean follow-up period was 37.6 months. The following postoperative CT scanning—documented grades were determined: Grade I, 160 screws (86.5%); Grade II, 15 (8.1%); Grade III, six (3.2%); Grade IV, three (1.6%); and Grade V, one (0.5%). Among cases involving screw misplacements, Grade II placement was most common, and this occurred most frequently in the middle thoracic region. Conclusions. The authors' grading system has advantages over those previously described; however, further study to determine its reliability, reproducibility, and predictive value of clinical sequelae is warranted. Postoperative CT scanning should be considered the gold standard for evaluating thoracic pedicle screw placement.

Surgical anatomy of the C-2 pedicle

2001 ◽  
Vol 95 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Jay U. Howington ◽  
John J. Kruse ◽  
Deepak Awasthi
Keyword(s):  
Sagittal Plane ◽  
Pedicle Screws ◽  
Anatomical Study ◽  
Ct Scanning ◽  
Surgical Anatomy ◽  
Screw Placement ◽  
Preoperative Imaging ◽  
Direct Visualization ◽  
Content Type ◽  
Fine Print

Object. The goal of this anatomical study was to investigate the surgical and radiographic anatomy of the C-2 pedicle in relation to transpedicular screw placement in occipitocervical stabilization and to establish anatomical guidelines for the placement of C-2 pedicle screws. Methods. The C-2 pedicles in 10 cadaveric spines were evaluated using both computerized tomography (CT) scanning and manual measurements. The specimens were scanned; the mediolateral and rostrocaudal angulations of each pedicle were measured, with the midline sagittal plane and the inferior endplate of the C-2 facet, respectively, as references, and values were recorded in 1° increments by using a digital goniometer. The height, width, and length of the pedicles were also measured on the CT scans. Based on these measurements in conjunction with direct visualization of the C-2 pedicle through the C1–2 interlaminar space pedicle screws were then placed. The distances from the screw entry point to the midline, C2–3 joint line, and the medial aspect of the vertebral artery were also measured. Repeated CT scanning was then performed to assess screw placement. The average pedicle height, width, and length measured 9.1 mm, 7.9 mm, and 16.6 mm, respectively, and the medial inclination and rostrocaudal angulation averaged 35.2° and 38.8°, respectively. The cortex of the pedicle was not violated in any of the 20 cadaveric specimens. Conclusions. Adequate preoperative imaging studies in conjunction with direct visualization of the C-2 pedicle make transpedicular fixation safe and effective.

Increased pedicle screw pullout strength with vertebroplasty augmentation in osteoporotic spines

2002 ◽  
Vol 96 (3) ◽  
pp. 309-312 ◽  
Author(s):  
John S. Sarzier ◽  
Avery J. Evans ◽  
David W. Cahill
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Pullout Strength ◽  
Mineral Density ◽  
Content Type ◽  
Pullout Force ◽  
Grade Ii ◽  
The Mean ◽  
Grade Iii ◽  
Fine Print

Object. The authors conducted a biomechanical study to evaluate pedicle screw pullout strength in osteoporotic cadaveric spines. Nonaugmented hemivertebrae were compared with pressurized polymethylmethacrylate (PMMA)—augmented hemivertebrae. Methods. Six formalin-fixed cadaveric thoracolumbar spines at least two standard deviations below the mean bone mineral density (BMD) for age were obtained. Radiographic and BMD studies were correlated to grades I, II, and III osteoporosis according to the Jekei scale. Each of the 21 vertebrae underwent fluoroscopic placement of 6-mm transpedicular screws with each hemivertebra serving as the control for the contralateral PMMA-augmented hemivertebra. Pedicle screws were then evaluated for biomechanical axial pullout resistance. Augmented hemivertebrae axial pullout forces were increased (p = 0.0005). The mean increase in pullout force was 181% for Grade I, 206% for Grade II, and 213% for Grade III osteoporotic spines. Augmented Grade I osteoporotic spines demonstrated axial pullout forces near those levels reported in the literature for nonosteoporotic specimens. Augmented Grade II osteoporotic specimens demonstrated increases to levels found in nonaugmented vertebrae with low-normal BMD. Augmented Grade III osteoporotic specimens had increases to levels equal to those found in nonaugmented Grade I vertebrae. Conclusions. Augmentation of osteoporotic vertebrae in PMMA-assisted vertebroplasty can significantly increase pedicle screw pullout forces to levels exceeding the strength of cortical bone. The maximum attainable force appears to be twice the pullout force of the nonaugmented pedicle screw for each osteoporotic grade.

Use of a guide device to place pedicle screws in the thoracic spine: a cadaveric study

2001 ◽  
Vol 94 (2) ◽  
pp. 328-333 ◽  
Author(s):  
Jee Soo Jang ◽  
Won Bok Lee ◽  
Hansen A. Yuan
Keyword(s):  
Thoracic Spine ◽  
Pedicle Screws ◽  
Lateral Wall ◽  
Cadaveric Study ◽  
Medial Wall ◽  
Screw Placement ◽  
Content Type ◽  
Thoracic Pedicle Screws ◽  
Guide Device ◽  
Fine Print

✓ In this cadaveric study, the safety and accuracy of a specially designed guide device for the placement of thoracic pedicle screws was investigated in a normal anatomical situation. Five embalmed human cadaveric thoracic spines (T1–12) were used for the study of transpedicular screw placement in the thoracic spine. Overall 120 screws were placed at all thoracic levels. The screws were inserted bilaterally in the thoracic pedicles by using a specially designed guide device. No radiographs or other imaging studies were obtained. Following screw placement, computerized tomography scans were performed to evaluate the accuracy of the pedicle screw positioning. Seven (5.8%) of the screws penetrated the pedicle wall or the vertebral body (VB) cortex. Two screws (1.7%) penetrated the medial wall of the pedicle. Two screws (1.7%) penetrated the lateral wall of the pedicle, and one screw (0.8%) penetrated the lateral wall of the pedicle and the anterior VB cortex simultaneously. Two screws (1.7%) penetrated the anterior VB cortex. Compared with the results of other studies, the findings here indicate that using this device to guide the placement of thoracic pedicle screws can significantly reduce the incidence of pedicle penetration, particularly in the medial wall.

Comparison of computerized tomography and direct visualization in thoracic pedicle screw placement

2002 ◽  
Vol 97 (2) ◽  
pp. 223-226 ◽  
Author(s):  
Ganesh Rao ◽  
Darrel S. Brodke ◽  
Matthew Rondina ◽  
Andrew T. Dailey
Keyword(s):  
Pedicle Screw ◽  
Computerized Tomography ◽  
Predictive Value ◽  
Ct Scanning ◽  
Screw Placement ◽  
Direct Visualization ◽  
Pedicle Screw Placement ◽  
Content Type ◽  
Thoracic Pedicle Screw ◽  
Fine Print

Object. To validate computerized tomography (CT) scanning as a tool to assess the accuracy of thoracic pedicle screw placement, the authors compared its accuracy with that of direct visualization in instrumented cadaveric spine specimens. Methods. A grading scale was devised to score the placement of the pedicle screw. The grades ranged from 0 to 3 depending on the extent to which the pedicle had been violated. One hundred fifty-five pedicles were fitted with instrumentation in eight cadaveric spines. A single observer graded the appearance of the screw based on CT scans (3-mm axial sections with 1-mm overlap) and direct visualization of the specimen. The authors arrived at a Kappa value of 0.51, which suggested only moderate agreement between the two measurement techniques. Whereas CT had a positive predictive value of 95%, it had a negative predictive value of 62%. Conclusions. The authors thus conclude that although CT scanning is the most valid tool to assess the accuracy of thoracic pedicle screw placement, it tends to overestimate the number of misplaced screws.

Progressive neurological deficits with benign intracerebral cysts

1986 ◽  
Vol 65 (5) ◽  
pp. 706-709 ◽  
Author(s):  
Yoko Nakasu ◽  
Jyoji Handa ◽  
Kazuyoshi Watanabe
Keyword(s):  
Histological Examination ◽  
Computerized Tomography ◽  
Cyst Wall ◽  
Benign Lesion ◽  
Ct Scanning ◽  
Neurological Deficits ◽  
Review Of The Literature ◽  
Content Type ◽  
Ct Findings ◽  
Fine Print

✓ Two patients with benign intracerebral cysts are reported and a brief review of the literature is given. Although computerized tomography (CT) scanning is useful in detecting a variety of intracerebral cysts, the CT findings are not specific for any lesion. An exploratory operation with establishment of an adequate route of drainage and a histological examination of the cyst wall are mandatory in the management of patients with a progressive but benign lesion.

The use of computerized tomography in the diagnosis of cerebral hydatid cysts

1979 ◽  
Vol 50 (3) ◽  
pp. 339-342 ◽  
Author(s):  
Tuncalp Özgen ◽  
Aykut Erbengi ◽  
Vural Bertan ◽  
Süleyman Saǧlam ◽  
Özdemir Gürçay ◽  
...  
Keyword(s):  
Hydatid Cyst ◽  
Computerized Tomography ◽  
Ct Scanning ◽  
Hydatid Cysts ◽  
Content Type ◽  
Cerebral Hydatid Cyst ◽  
Cyst Membrane ◽  
Fine Print

✓ Eleven cases of cerebral hydatid cyst, diagnosed by computerized tomography (CT), are presented. The importance of CT in minimizing the possibility of accidentally tapping or tearing the cyst membrane is stressed. Repeat CT scanning after removal of the cyst revealed atrophy in the affected hemisphere.

Age-related changes in the proportion of intracranial cerebrospinal fluid space measured using volumetric computerized tomography scanning

2002 ◽  
Vol 97 (3) ◽  
pp. 607-610 ◽  
Author(s):  
Hiroshi Wanifuchi ◽  
Takashi Shimizu ◽  
Takashi Maruyama
Keyword(s):  
Cerebrospinal Fluid ◽  
Computerized Tomography ◽  
Ct Scanning ◽  
Volume Measurement ◽  
Intracranial Volume ◽  
Content Type ◽  
Standard Curve ◽  
Age Related ◽  
Fine Print ◽  
Age Related Changes

Object. The purpose of this study was to establish a standard curve to demonstrate normal age-related changes in the proportion of intracranial cerebrospinal fluid (CSF) space in intracranial volume (ICV) during each decade of life. Methods. Using volumetric computerized tomography (CT) scanning and computer-guided volume measurement software, ICV and cerebral parenchymal volume (CPV) for each decade of life were measured and the intracranial CSF ratio was calculated by the following formula: percentage of CSF = (ICV − CPV)/ICV × 100%. The standard curve for age-related changes in normal percentages of intracranial CSF was obtained. Conclusions. Based on this standard curve, the percentage of intracranial CSF rapidly increased after the sixth decade, seeming to reflect the brain atrophy that accompanies increased age.

Successful stereotaxic evacuation of an acute pontomedullary hematoma

1985 ◽  
Vol 62 (1) ◽  
pp. 153-156 ◽  
Author(s):  
D. Andries Bosch ◽  
Gustaaf N. Beute
Keyword(s):  
Arteriovenous Malformation ◽  
Young Woman ◽  
Computerized Tomography ◽  
Ct Scanning ◽  
Vascular Lesion ◽  
Content Type ◽  
Healthy Young Woman ◽  
First Child ◽  
Fine Print

✓ A healthy young woman developed a rapidly progressive pontomedullary lesion 24 hours after delivery of her first child. The lesion was shown on computerized tomography (CT) to be a primary hematoma. Stereotaxic aspiration was carried out, and the patient recovered. Angiography and CT scanning demonstrated a vascular lesion compatible with an arteriovenous malformation.

Effect of frameless stereotaxy on the accuracy of C1–2 transarticular screw placement

2001 ◽  
Vol 95 (1) ◽  
pp. 74-79 ◽  
Author(s):  
Orin Bloch ◽  
Langston T. Holly ◽  
Jongsoo Park ◽  
Chinyere Obasi ◽  
Kee Kim ◽  
...  
Keyword(s):  
Image Guidance ◽  
Vascular Anatomy ◽  
Ct Scanning ◽  
Screw Placement ◽  
Frameless Stereotaxy ◽  
Transarticular Screw ◽  
Anterior Cortex ◽  
Content Type ◽  
Pars Interarticularis ◽  
Fine Print

Object. In recent studies some authors have indicated that 20% of patients have at least one ectatic vertebral artery (VA) that, based on previous criteria in which preoperative computerized tomography (CT) and standard intraoperative fluoroscopic techniques were used, may prevent the safe placement of C1–2 transarticular screws. The authors conducted this study to determine whether frameless stereotaxy would improve the accuracy of C1–2 transarticular screw placement in healthy patients, particularly those whom previous criteria would have excluded. Methods. The authors assessed the accuracy of frameless stereotaxy for C1–2 transarticular screw placement in 17 cadaveric cervical spines. Preoperatively obtained CT scans of the C-2 vertebra were registered on a stereotactic workstation. The dimensions of the C-2 pars articularis were measured on the workstation, and a 3.5-mm screw was stereotactically placed if the height and width of the pars interarticularis was greater than 4 mm. The specimens were evaluated with postoperative CT scanning and visual inspection. Screw placement was considered acceptable if the screw was contained within the C-2 pars interarticularis, traversed the C1–2 joint, and the screw tip was shown to be within the anterior cortex of the C-1 lateral mass. Transarticular screws were accurately placed in 16 cadaveric specimens, and only one specimen (5.9%) was excluded because of anomalous VA anatomy. In contrast, a total of four specimens (23.5%) showed significant narrowing of the C-2 pars interarticularis due to vascular anatomy that would have precluded atlantoaxial transarticular screw placement had previous nonimage-guided criteria been used. Conclusions. Frameless stereotaxy provides precise image guidance that improves the safety of C1–2 transarticular screw placement and potentially allows this procedure to be performed in patients previously excluded because of the inaccuracy of nonimage-guided techniques.

Three-dimensional computerized tomography angiography in patients with hyperacute intracerebral hemorrhage

1999 ◽  
Vol 91 (3) ◽  
pp. 424-431 ◽  
Author(s):  
Yasuo Murai ◽  
Ryo Takagi ◽  
Yukio Ikeda ◽  
Yasuhiro Yamamoto ◽  
Akira Teramoto
Keyword(s):  
Intracerebral Hemorrhage ◽  
Ct Angiography ◽  
Computerized Tomography ◽  
Three Dimensional ◽  
Ct Scanning ◽  
3D Ct ◽  
Content Type ◽  
Hematoma Enlargement ◽  
3D Ct Angiography ◽  
Fine Print

Object. The authors confirm the usefulness of extravasation detected on three-dimensional computerized tomography (3D-CT) angiography in the diagnosis of continued hemorrhage and establishment of its cause in patients with acute intracerebral hemorrhage (ICH).Methods. Thirty-one patients with acute ICH in whom noncontrast and 3D-CT angiography had been performed within 12 hours of the onset of hemorrhage and in whom conventional cerebral angiographic studies were obtained during the chronic stage were prospectively studied. Noncontrast CT scanning was repeated within 24 hours of the onset of ICH to evaluate hematoma enlargement.Findings indicating extravasation on 3D-CT angiography, including any abnormal area of high density on helical CT scanning, were observed in five patients; three of these demonstrated hematoma enlargement on follow-up CT studies. Thus, specificity was 60% (three correct predictions among five positives) and sensitivity was 100% (19 correct predictions among 19 negatives). Evidence of extravasation on 3D-CT angiography indicates that there is persistent hemorrhage and correlates with enlargement of the hematoma.Regarding the cause of hemorrhage, five cerebral aneurysms were visualized in four patients, and two diagnoses of moyamoya disease and one of unilateral moyamoya phenomenon were made with the aid of 3D-CT angiography. Emergency surgery was performed without conventional angiography in one patient who had an aneurysm, and it was clipped successfully.Conclusions. Overall, 3D-CT angiography was found to be valuable in the diagnosis of the cause of hemorrhage and in the detection of persistent hemorrhage in patients with acute ICH.

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