Frameless stereotaxy for anterior spinal procedures

2001 ◽  
Vol 95 (2) ◽  
pp. 196-201 ◽  
Author(s):  
Langston T. Holly ◽  
Orin Bloch ◽  
Chinyere Obasi ◽  
J. Patrick Johnson
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Optical Tracking ◽  
Frameless Stereotaxy ◽  
Anatomical Landmarks ◽  
Content Type ◽  
Registration Error ◽  
The Mean ◽  
K Wires ◽  
Fine Print

Object. Intraoperative image guidance provides real-time three-dimensional visualization and has been successfully applied in many posterior spinal procedures. The feasibility of applying these techniques to anterior spinal surgery has not been studied systematically because the anterior spine, in contrast to the posterior spine, lacks distinct anatomical landmarks for registration. The authors sought to evaluate the practicality of performing stereotaxy in the anterior spine in a cadaveric model. Methods. Unilateral C4—L4 pedicle screws were placed posteriorly in three cadaveric specimens to serve as unknown markers within each vertebral body. The specimens then underwent computerized tomography (CT) scanning, and the CT data were transferred to an optical tracking system. The anterior surface of the spine was registered for use with the stereotactic system by using a paired point—matching technique. Attached to a surgical drill, K-wires were placed under stereotactic guidance in a tip-to-tip orientation with the posterior pedicle screws. A second postoperative CT scan was obtained, and accuracy was determined by measuring the distance between the tips of the K-wire and pedicle screw. The K-wires were placed tip to tip with pedicle screw markers in 57 vertebral levels. The mean registration error was 1.47 ± 0.04 mm, and when combined with the universal instrument registration error of 0.7 mm yielded an overall registration error of 2.17 ± 0.04 mm. The mean tip-to-tip distance for all K-wires placed was 2.46 ± 0.23 mm. The difference between the mean tip-to-tip distance and overall registration error was not statistically significant (p > 0.05), indicating that the K-wires were placed within the expected range of error. Conclusions. The results of this study confirmed the feasibility of performing anterior stereotactic procedures throughout the spine. The accuracy of the findings in this study indicates that anterior stereotaxy should be applicable in clinical practice.

Three-dimensional fluoroscopy-guided percutaneous thoracolumbar pedicle screw placement

2003 ◽  
Vol 99 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Langston T. Holly ◽  
Kevin T. Foley
Keyword(s):  
Pedicle Screw ◽  
Three Dimensional ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Content Type ◽  
Image Guided ◽  
Spinal Navigation ◽  
Mean Diameter ◽  
The Mean ◽  
Fine Print

✓ The authors sought to evaluate the feasibility and accuracy of three-dimensional (3D) fluoroscopic guidance for percutaneous placement of thoracic and lumbar pedicle screws in three cadaveric specimens. After attaching a percutaneous dynamic reference array to the surgical anatomy, an isocentric C-arm fluoroscope was used to obtain images of the region of interest. Light-emitting diodes attached to the C-arm unit were tracked using an electrooptical camera. The image data set was transferred to the image-guided workstation, which performed an automated registration. Using the workstation display, pedicle screw trajectories were planned. An image-guided drill guide was passed through a stab incision, and this was followed by sequential image-guided pedicle drilling, tapping, and screw placement. Pedicle screws of various diameters (range 4–6.5 mm) were placed in all pedicles greater than 4 mm in diameter. Postoperatively, thin-cut computerized tomography scans were obtained to determine the accuracy of screw placement. Eighty-nine (94.7%) of 94 percutaneous screws were placed completely within the cortical pedicle margins, including all 30 lumbar screws (100%) and 59 (92%) of 64 thoracic screws. The mean diameter of all thoracic pedicles was 6 mm (range 2.9–11 mm); the mean diameter of the five pedicles in which wall violations occurred was 4.6 mm (range 4.1–6.3 mm). Two of the violations were less than 2 mm beyond the cortex; the others were between 2 and 3 mm. Coupled with an image guidance system, 3D fluoroscopy allows highly accurate spinal navigation. Results of this study suggest that this technology will facilitate the application of minimally invasive techniques to the field of spine surgery.

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.

Application of frameless stereotaxy to pedicle screw fixation of the spine

1995 ◽  
Vol 83 (4) ◽  
pp. 641-647 ◽  
Author(s):  
Iain H. Kalfas ◽  
Donald W. Kormos ◽  
Michael A. Murphy ◽  
Rick L. McKenzie ◽  
Gene H. Barnett ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Spinal Surgery ◽  
Screw Fixation ◽  
Ct Images ◽  
Pedicle Screw Fixation ◽  
Lumbosacral Spine ◽  
Frameless Stereotaxy ◽  
Content Type ◽  
Screw Length ◽  
Fine Print

✓ Interactive frameless stereotaxy has been successfully applied to intracranial surgery. It has contributed to the improved localization of deep-seated brain lesions and has demonstrated a potential for reducing both operative time and morbidity. However, it has not been as effectively applied to spinal surgery. The authors describe the application of frameless stereotactic techniques to spinal surgery, specifically pedicle screw fixation of the lumbosacral spine. Preoperative axial computerized tomography (CT) images of the appropriate spinal segments are obtained and loaded onto a high-speed graphics supercomputer workstation. Intraoperatively, these images can be linked to the appropriate spinal anatomy by a sonic localization digitizer device that is interfaced with the computer workstation. This permits the surgeon to place a pointing device (sonic wand) on any exposed spinal bone landmark in the operative field and obtain multiplanar reconstructed CT images projected in near-real time on the workstation screen. The images can be manipulated to assist the surgeon in determining the proper entry point for a pedicle screw as well as defining the appropriate trajectory in the axial and sagittal planes. It can also define the correct screw length and diameter for each pedicle to be instrumented. The authors applied this device to the insertion of 150 screws into the lumbosacral spines of 30 patients. One hundred forty-nine screws were assessed to be satisfactorily placed by postoperative CT and plain film radiography. In this report the authors discuss their use of this device in the clinical setting and review their preliminary results of frameless stereotaxy applied to spinal surgery. On the basis of their findings, the authors conclude that frameless stereotactic technology can be successfully applied to spinal surgery.

Minimally invasive transforaminal lumbar interbody fusion with ipsilateral pedicle screw and contralateral facet screw fixation

2005 ◽  
Vol 3 (3) ◽  
pp. 218-223 ◽  
Author(s):  
Jee-Soo Jang ◽  
Sang-Ho Lee
Keyword(s):  
Minimally Invasive ◽  
Pedicle Screw ◽  
Interbody Fusion ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Content Type ◽  
The Mean ◽  
Level Fusion ◽  
Fine Print

Object. The purpose of this study was to introduce a minimally invasive transforaminal lumbar interbody fusion (TLIF) technique that involves ipsilateral pedicle screw (PS) and contralateral facet screw (FS) fixation. Methods. Eight men and 15 women (mean age 59.5 years, range 48–68) underwent the aforementioned TLIF procedure for degenerative spondylolisthesis and uni- or bilateral radiculopathy. Twenty-two patients underwent one-level fusion and one patient two-level fusion (L4—S1). In all cases the various procedures were undertaken via one small incision. There were no intraoperative complications. The mean estimated blood loss (EBL) was 310 ml, and the mean operative time was 150 minutes in cases of one-level fusion. The follow-up period ranged from 13 to 28 months (mean 19 months). The mean Numeric Rating Scale score reflected improvement-reductions from 7.5 (back pain) and 7.4 (leg pain) to 2.3 and 0.7, respectively (p < 0.0001). The mean Oswestry Disability Index (ODI) scores also reflected improved status (ODI of 33.1 before the surgery to 7.6 after the surgery; p < 0.0001). Examination indicated that 22 of 24 fusion sites exhibited osseous union. At the last follow-up examination, satisfactory outcomes were observed in 21 out of 23 patients. Conclusions. The TLIF with ipsilateral PS and contralateral FS fixation has the advantages over the conventional TLIF of reduced EBL and diminished soft-tissue injury.

Percutaneous pedicle screw fixation of the lumbar spine: preliminary clinical results

2002 ◽  
Vol 97 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Kevin T. Foley ◽  
Sanjay K. Gupta
Keyword(s):  
Lumbar Spine ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Posterior Fixation ◽  
Content Type ◽  
Insertion Device ◽  
Lumbar Pedicle ◽  
Fine Print

Object. Standard techniques for pedicle screw fixation of the lumbar spine involve open exposures and extensive muscle dissection. The purpose of this study was to report the initial clinical experience with a novel device for percutaneous posterior fixation of the lumbar spine. Methods. An existing multiaxial lumbar pedicle screw system was modified to allow screws to be placed percutaneously by using an extension sleeve that permits remote manipulation of the polyaxial screw heads and remote engagement of the screw-locking mechanism. A unique rod-insertion device was developed that linked to the screw extension sleeves, allowing for a precut and -contoured rod to be placed through a small stab wound. Because the insertion device relies on the geometrical constraint of the rod pathway through the screw heads, minimal manipulation is required to place the rods in a standard submuscular position, there is essentially no muscle dissection, and the need for direct visual feedback is avoided. Twelve patients (six men and six women) who ranged in age from 23 to 68 years underwent pedicle screw fixation in which the rod-insertion device was used. Spondylolisthesis was present in 10 patients and osseous nonunion of a prior interbody fusion was present in two. All patients underwent successful percutaneous fixation. Ten patients underwent single-level fusions (six at L5—S1, three at L4–5, and one at L2–3), and two underwent two-level fusions (one from L3–5 and the other from L4—S1). The follow-up period ranged from 10 to 19 months (mean 13.8 months). Conclusions. Although percutaneous lumbar pedicle screw placement has been described previously, longitudinal connector (rod or plate) insertion has been more problematic. The device used in this study allows for straightforward placement of lumbar pedicle screws and rods through percutaneous stab wounds. Paraspinous tissue trauma is minimized without compromising the quality of spinal fixation. Preliminary experience involving the use of this device has been promising.

One-stage posterior decompression and reconstruction of the cervical spine by using pedicle screw fixation systems

1999 ◽  
Vol 90 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Kuniyoshi Abumi ◽  
Kiyoshi Kaneda ◽  
Yasuhiro Shono ◽  
Masanori Fujiya
Keyword(s):  
Cervical Spine ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Spinal Cord Tumor ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Posterior Decompression ◽  
Content Type ◽  
One Stage ◽  
Fine Print

Object. This retrospective study was conducted to analyze the results of one-stage posterior decompression and reconstruction of the cervical spine by using pedicle screw fixation systems in 46 patients. Methods. Causes of cervical myelopathy in these 46 patients included spondylosis or ossification of the posterior longitudinal ligament, rheumatoid arthritis, metastatic or primary vertebral tumors, cervical spinal injuries, and spinal cord tumor. Thirty-three patients underwent this one-stage procedure as primary surgery. In the remaining 13 patients who had previously undergone laminectomies, the one-stage procedure was performed as salvage surgery. Cervical pedicle screws were inserted into the pedicles after probing and tapping. Graft bone was placed on the bilateral lateral masses, and pedicle screws were interconnected longitudinally by either plates or rods. Postoperatively, 26 patients showed improved neurological status (at least one grade improvement on Frankel's functional classification). There were no cases of neurological deterioration postoperatively. Solid bony fusion was obtained in all patients, except in seven patients with metastatic tumor who did not receive bone grafts. Correction of kyphosis was satisfactory. Postoperative radiological evaluation revealed that 10 (5.3%) of 190 screws inserted into the cervical vertebrae had perforated the cortex of the pedicles; however, no neurovascular complications were caused by the perforations. Conclusions. The pedicle screw fixation procedure, which does not require the lamina to be used as a stabilizing anchor, has proven to be valuable when performing one-stage posterior decompressive and reconstructive surgery in the cervical spine. The risk to neurovascular structures in this procedure, however, cannot be completely eliminated. Thorough knowledge of local anatomy and application of established surgical techniques are essential for this procedure.

Evaluation of pedicle screw position on computerized tomography scans

2003 ◽  
Vol 98 (1) ◽  
pp. 104-109
Author(s):  
Jin Sup Yeom ◽  
Moon Sang Chung ◽  
Choon-Ki Lee ◽  
Yeongho Kim ◽  
Namkug Kim ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Computerized Tomography ◽  
Pedicle Screws ◽  
Ct Scans ◽  
Metal Artifact ◽  
Content Type ◽  
Screw Insertion ◽  
Bone Window ◽  
Screw Position ◽  
Fine Print

✓ The quality of a computerized tomography (CT) scan is significantly reduced by metal artifact caused by a pedicle screw system. The purpose of this study was to develop a method of facilitating the evaluation of pedicle screw position on CT scans obtained after screw insertion. The authors developed an algorithm to process spiral CT scans in a personal computer. This uses a digital image enhancement technique, the curve change-based intensity transformation algorithm. This method can generate a clear image of the screw outlines while reducing metal artifact. The resulting images are displayed in arbitrary planes as well as in axial, coronal, and sagittal planes, to support better the evaluation of pedicle screw position. The algorithm was tested using CT scans obtained in 37 patients in whom 186 pedicle screws had been placed. There were five types of screw systems, all of which were made of titanium alloys. In all cases algorithm-based determination of screw position became more convenient and more accurate than when using the conventional bone window setting. In addition, it provided better soft-tissue visualization than the bone window. The software, by displaying clear outlines of screws and decreasing metal artifact, as well as by reconstructing the images in arbitrary planes, was more helpful in identifying the position of pedicle screws than the conventional bone window setting.

Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 2: Treatment with threaded interbody cages/dowels and pedicle screws

2001 ◽  
Vol 94 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Sedat Çagli ◽  
Neil R. Crawford ◽  
Volker K. H. Sonntag ◽  
Curtis A. Dickman
Keyword(s):  
Pedicle Screw ◽  
Degenerative Spondylolisthesis ◽  
Pedicle Screws ◽  
Cyclic Fatigue ◽  
Pedicle Screw Fixation ◽  
Biomechanical Stability ◽  
Content Type ◽  
Degenerative Lumbar Spondylolisthesis ◽  
Lumbar Spondylolisthesis ◽  
Fine Print

Object. The authors sought to determine the biomechanical effectiveness of threaded interbody cages or dowels compared with that achieved using pedicle screw instrumentation in resisting Grade I lumbar spine degenerative spondylolisthesis. Methods. Thirty-three levels obtained from seven cadaveric lumbar spines were instrumented with cages or dowels, pedicle screw/rod instrumentation, or both. Entire specimens were loaded with nonconstraining torques. Each level was loaded with anteroposterior shear forces while an optical system was used to measure the specimen's motion at individual levels. Pedicle screw/rods outperformed interbody cages and dowels in treating spondylolisthesis. Cages or dowels alone provided only moderate biomechanical stability, and their effectiveness depended heavily on the integrity of the ligaments and remaining annulus, whereas the success of pedicle screw fixation relied predominantly on the integrity of the bone for solid fixation. Little biomechanical difference was demonstrated between cages and dowels; both devices were susceptible to loosening with cyclic fatigue. Conclusions. Biomechanically, cages or dowels alone were suboptimal for treating lumbar spondylolisthesis, especially compared with pedicle screw/rods. Threaded cages or dowels used together with pedicle screws/rods created the most stable construct.

Thoracic transfacet pedicle screw fixation: a new instrumentation technique

2005 ◽  
Vol 3 (3) ◽  
pp. 224-229 ◽  
Author(s):  
Atilla Akbay ◽  
Serkan İnceoğlu ◽  
Ryan Milks ◽  
Richard Schlenk ◽  
Selcuk Palaoglu ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Transverse Process ◽  
Pedicle Screw Fixation ◽  
Content Type ◽  
Thoracic Surgical Procedures ◽  
Flexion Extension ◽  
Fixation Techniques ◽  
Fine Print

Object. Pedicle screw instrumentation of the thoracic spine remains technically challenging. Transverse process and costotransverse screw fixation techniques have been described as alternatives to pedicle screw fixation (PSF). In this study, the authors introduce thoracic transfacet PSF and compare its experimental biomechanical results with those of standard PSF in short-term cyclic loading in cadaveric thoracic specimens. Methods. Specimens were tested intact for six cycles at compressive loads of 250 N offset by 1 cm along appropriate axes to induce flexion, extension, and left and right lateral bending. The specimens were then fixed with either a pedicle screw/rod construct or transfacet pedicle screws and retested in the same fashion. After this sequence, specimens were loaded until failure in flexion mode at a rate of 5 mm/minute was observed. Both fixation constructs provided significantly greater stiffnesses than that demonstrated when the specimen was intact (p < 0.05, two-way analysis of variance). Additionally, the two constructs were statistically equivalent in terms of stiffness and load-to-failure values (p < 0.05, two-tailed nonpaired t-test). The only difference observed was that the low midthoracic region (T7–9) was biomechanically weaker than the upper midthoracic and lower thoracic areas in flexion after the destabilization and instrumentation-augmented stabilization procedures. Conclusions. In selected thoracic surgical procedures, transfacet PSF may, after analysis of long-term biomechanical data, potentially become a reasonable alternative to conventional PSF.

Percutaneous pedicle screw placement with computer-navigated mapping in place of Kirschner wires

2013 ◽  
Vol 19 (5) ◽  
pp. 608-613 ◽  
Author(s):  
Thomas J. Gianaris ◽  
Gregory M. Helbig ◽  
Eric M. Horn
Keyword(s):  
Pedicle Screw ◽  
Navigation System ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Computer Assisted ◽  
Anatomical Landmarks ◽  
Pedicle Screw Placement ◽  
Assisted Navigation ◽  
Percutaneous Pedicle Screw ◽  
K Wires

Object Percutaneous pedicle screw insertion techniques are commonly used to treat a variety of spinal disorders. Typically, Kirschner (K)-wires are used to guide the insertion of taps and screws during placement since the normal anatomical landmarks are not visualized. The use of K-wires adds risks, such as vascular and nerve injuries as well as increased radiation exposure given the use of fluoroscopy. The authors describe a series of patients who had percutaneous pedicle screws placed using a new computer-assisted navigation technique without the need for K-wires. Methods Minimally invasive percutaneous pedicle screw placement in the thoracic and lumbar spine was performed in a consecutive series of 15 patients for a variety of spinal pathologies. Intraoperative 3D CT images were obtained and used with a computer-assisted navigation system to insert an awl-tap into each pedicle. The tap location in the pedicle was marked with the navigation software, and the awl-tap was then removed. The navigation system was used to identify each landmark to insert the pedicle screw. Connecting rods were then inserted percutaneously under fluoroscopic guidance. Postoperative CT scans were obtained in each patient to evaluate screw placement. Results On postprocedure scanning, only 1 screw had a minor lateral and superior breach that was asymptomatic. To date, there have been no hardware failures. Conclusions Percutaneous pedicle screws can be placed effectively and safely without the use of K-wires.

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