Esophageal injury from thoracic pedicle screw placement in a polytrauma patient: a case report and literature review

A quantitative accuracy assessment of the use of a rigid robotic arm in navigated placement of 726 pedicle screws

Background

Traditional minimally invasive fluoroscopy-based techniques for pedicle screw placement utilize guidance, which may require fluoroscopic shots. Computerized tomography (CT) navigation results in more accurate screw placement. Robotic surgery seeks to establish access and trajectory with greater accuracy.

Objective

This study evaluated the screw placement accuracy of a robotic platform.

Methods

Demographic data, preoperative/postoperative CT scans, and complication rates of 127 patients who underwent lumbosacral pedicle screw placement with minimally invasive navigated robotic guidance using preoperative CT were analyzed.

Results

On the GRS scale, 97.9% (711/726) of screws were graded A or B, 1.7% (12/726) of screws graded C, 0.4% (3/726) of screws graded D, and 0% graded E. Average offset from preoperative plan to final screw placement was 1.9 ± 1.5 mm from tip, 2.2 ± 1.4 mm from tail and 2.9 ± 2.3° of angulation.

Conclusions

Robotic-assisted surgery utilizing preoperative CT workflow with intraoperative fluoroscopy-based registration improves pedicle screw placement accuracy within a patient’s pedicles.

Intraoperative 3D imaging with cone-beam computed tomography leads to revision of pedicle screws in dorsal instrumentation: a retrospective analysis

Background

Correct positioning of pedicle screws can be challenging. Intraoperative imaging may be helpful. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. 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.

Methods

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. This study first evaluates intraoperative imaging. 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. 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.

Results

During the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. 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. Fifty-six (11.2%) screws in SG 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. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C–E).

Conclusion

This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. Misplacement of screws cannot always be prevented. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws.

Evaluation of Software-Based Metal Artifact Reduction in Intraoperative 3D Imaging of the Spine Using a Mobile Cone Beam CT

The aim of our study was to evaluate whether software-based artifact reduction can achieve an improved image quality, using intraoperative 3D imaging in spinal surgery. A total of 49 intraoperative 3D image datasets of patients, who underwent surgery with pedicle screw placement, were retrospectively evaluated. The visibility of anatomical structures and the diameter of the pedicle screws were examined, with and without the application of the artifact reduction software. All software prototypes can improve the visibility of anatomical structures (P < 0.01), except MAR (metal artifact reduction) combined with IRIS (iterative reconstruction in image space) (P = 0.04). The algorithms MAR and MAR-2 can reduce the blooming artifacts significantly (P < 0.01), but SL (Shepp & Logan) cannot (P = 0.08-0.988). In summary, software-based artifact reduction for intraoperative 3D datasets can improve the current image quality. Additional information regarding the implant placement and the fracture reduction is therefore generated for the surgeon.

Screw Malposition: Are There Long-term Repercussions to Malposition of Pedicle Screws?

BACKGROUND/INTRODUCTION

Pedicle screws have long been part of the continued advancements in spine surgery. Despite the many techniques that have been devised for their safe placement, malposition of screws continues to occur. Studies have evaluated the possible safe limits of screw malposition, and have given some insight on anatomic variation in spinal deformity. Review of the literature reveals several cases of deleterious long-term sequelae of malpositioned screws.

DISCUSSION

With the current experience, proposed recommendations are provided to detect and avoid the potential long-term sequelae. Though the literature has helped to define possible concerning screws, there are no good studies predicting long-term risk.

CONCLUSION

Improvements in technology and techniques, advancements in intraoperative confirmation and postoperative surveillance, studies that assist risk stratification, and expert consensus evaluations will help guide surgeons in their decision for addressing misplaced screws.

Esophageal perforation following pedicle screw placement for the treatment of upper thoracic spinal tuberculosis: a case report and review of the literature

Background

The technique of posterior pedicle screw fixation has already been widely applied in the treatment of upper thoracic spinal tuberculosis. However, lesions of tuberculosis directly invade the vertebrae and surrounding soft tissues, which increases the risk of esophageal perforation induced by the posterior pedicle screw placement. Herein, we report the first case of esophageal perforation following pedicle screw placement in the upper thoracic spinal tuberculosis, and describe the underlying causes, as well as the treatment and prognosis.

Case presentation

A 48-year-old female patient with upper thoracic spinal tuberculosis presented sputum-like secretions from the wound after she was treated with one-stage operation through the posterolateral approach. Endoscopy was immediately conducted, which confirmed that the patient complicated with postoperative esophageal perforation caused by screws. CT scan showed that the right screw perforated the anterior cortex of the vertebrae and the esophagus at the T4 level. Fortunately, mediastinal infection was not observed. The T4 screw was removed, Vacuum Sealing Drainage (VSD) was performed, and jejunum catheterization was used for enteral nutrition. After continuous treatment with sensitive antibiotics for 2.5 months and 5 times of VSD aspiration, the infected wound recovered gradually. With 18-month follow-up, the esophagus healed well, without symptoms of dysphagia and stomach discomfort, and CT scan showed that T2–4 had complete osseous fusion without sequestrum.

Conclusion

Tuberculosis increases the risk of postoperative esophageal perforation in a certain degree for patients with upper thoracic tuberculosis. The damages to esophagus during the operation should be prevented. The screws with the length no more than 30 mm should be selected. Moreover, close monitoring after operation should be conducted to help the early identification, diagnosis and treatment, which could help preventing the adverse effects induced by the delayed diagnosis and treatment of esophageal perforation.

Is it an asymptomatic tracheal injury or misdiagnosis in treatment of vertebral fracture: A case report

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Pedicle screws are durable and safe tools that are frequently used in the treatment of vertebral fractures.

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The most important complications of the use of pedicle screws are vascular injuries, internal organ injuries and spinal cord injuries.

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Imaging methods, navigation systems, and cannulated pedicle screws should be used more frequently to reduce visceral organ injuries in the surgery of thoracic vertebral fractures.

Introduction

Pedicle screws are durable and safe instruments frequently used to treat vertebra injuries and deformities. There is also a possibility of medulla spinalis and visceral organ injury when the pedicle screws are delivered in unsuitable positions or dimensions. In this case, the authors want to draw attention to one of the visceral organ injuries during the thoracic pedicle screw placement.

Presentation of case

A 31 years old man underwent posterior instrumentation and fusion for T4 vertebra fractures. The patient was not symptomatic in the postoperative period. Tracheal pressure was observed at the 3rd thoracic vertebra level on the second day after the operation. No complications were encountered in the 3-year follow-up of the patient, who did not accept a second surgery recommended for screw replacement.

Discussion

During surgery for thoracic vertebral fractures, the shoulder joint makes it difficult to imagine as the shoulder bones enter the field of view. Therefore, the number of misplaced screws increases. Moreover, it increases the risk of internal organ injury.

Conclusion

The use of navigation systems or cannulated pedicle screws to treat thoracic vertebral fractures reduces internal organ injuries.

Esophageal perforation caused by a thoracic pedicle screw

This grand round raises the risk of a rare complication that can be avoided with the knowledge of the particular anatomy of scoliosis vertebra. Transpedicular screws have been reported to enhance the operative correction in scoliosis surgery. The narrow and inconsistent shape of the thoracic pedicles makes the placement of pedicle screws technically challenging. Furthermore, in thoracic curves, the close proximity of the spinal cord and major soft tissue structures also adds a greater risk to the procedure. The esophagus lies close to the upper thoracic vertebras and, an anterior cortical perforation can cause esophageal injury. We report a case of anterior cortical perforation by a T4 pedicle screw complicated by an esophageal perforation in a 15-year-old girl with convulsive encephalopathy. She was operated for a severe neurological scoliosis (Rett syndrome). Her neurological condition deteriorated 3 years after the posterior spinal surgery, requiring a percutaneous gastrostomy. An intra-esophageal screw was discovered incidentally during an endoscopy. We decided not to remove this screw, because the patient's health status presented a surgical contraindication. The patient showed no apparent discomfort at the 10-year follow-up examination after spinal arthrodesis. Esophageal perforation caused by a posterior pedicle screw is very rare. We highlight the risk of injury to esophagus from pedicle screws in upper thoracic vertebra. The systematic removal of a malpositioned screw must be discussed, on a case-to-case benefit-risk basis, especially if the patient has numerous comorbidities, given the long-term tolerance of a number of these improperly positioned implants.

Migration of spinal pedicle screw with aerodigestive perforation and subsequent device expectoration

INTRODUCTION

Spinal fixation is a common surgical procedure. Frequently, fixation for spinal stabilization requires use of instrumentation such as pedicle screws and fixation plates. Aerodigestive and vascular perforations from such procedures are infrequent albeit known complications from these procedures.

PRESENTATION OF CASE

This case details an uncommon situation in which a patient with anterior cervical spine fixation in the distant past was found to have a migratory pedicle screw. The patient had symptoms of neck pain and dysphagia. Radiographic studies were helpful in demonstrating the problem. While undergoing a physical examination, the patient was witnessed to expectorate the screw. Further work up with panendoscopy was undertaken and the patient managed conservatively.

DISCUSSION

The upper aerodigestive system rarely experiences perforation from spinal stabilization hardware. When it occurs, management should include a dedicated investigation of the involved portions of the digestive system to avoid further complication.

CONCLUSION

This case presents an rare occurrence of aerodigestive perforation of a spinal pedicle screw which was self-removed.

The use of fluoroscopic guided percutaneous pedicle screws in the upper thoracic spine (T1-T6): Is it safe?

PURPOSE

This study analysed the accuracy and safety of the fluoroscopic guided percutaneous screws in the upper thoracic vertebrae (T1-T6).

METHODS

Computed tomography scans from 74 patients were retrospectively evaluated between January 2008 and December 2012. Pedicle perforations were classified by two types of grading systems. For medial, lateral, superior and inferior perforations: grade 0 - no violation; grade 1 - <2 mm; grade 2 - 2-4 mm and grade 3 - >4 mm. For anterior perforations: grade 0 - no violation; grade 1 - <4 mm; grade 2 - 4-6 mm and grade 3 - >6 mm.

RESULTS

There were 35 (47.3%) male and 39 (52.7%) female patients with a total 260 thoracic pedicle screws (T1-T6) analysed. There were 32 screw perforations which account to a perforation rate of 12.3% (11.2% grade 1, 0.7% grade 2 and 0.4% grade 3). None led to pedicle screw-related complications. The perforation rate was highest at T1 (33.3%, all grade 1 perforations), followed by T6 (14.5%) and T4 (14.0%).

CONCLUSION

Fluoroscopic guided percutaneous pedicle screws of the upper thoracic spine (T1-T6) are technically more demanding and carry potential risks of serious complications. Extra precautions need to be taken when fluoroscopic guided percutaneous pedicle screws are placed at T1 and T2 levels, due to high medial pedicular angulation and obstruction of lateral fluoroscopic images by the shoulder girdle and at T4-T6 levels, due to smaller pedicular width.

Esophageal Perforation Caused by a Posterior Pedicle Screw: A Case Report

BACKGROUND

Posterior spinal instrumented fusion has received widespread acceptance in adolescent idiopathic scoliosis (AIS) treatment, there have been some potential complications resulted from screw misplacement. Esophagus is one of the vital structures close to the upper thoracic vertebras and is at risk for potential injury.

METHODS

A 15-year-old girl who underwent posterior instrumented fusion for AIS was admitted to our department 10 years later with a complaint of dysphagia due to an esophageal perforation from a malpositioned T4 pedicle screw (PS). After implant removal and nasogastric tube placement, oral feeding was started after 3 days and the patient was discharged from hospital after 1 week.

RESULTS

In 12 weeks, the esophageal perforation healed without complications.

CONCLUSIONS

This is the first case report of esophageal perforation by a posterior PS in an AIS patient. Esophagus is close to the upper thoracic vertebras and an anterior cortical perforation can cause esophageal injury if longer than 35 mm PSs are used. This unusual but potential complication must be kept in mind in scoliosis surgery.

LEVEL OF EVIDENCE

Level IV-case report.

Iliac vein compression syndrome from anterior perforation of a pedicle screw

May-Thurner syndrome is an anatomic variant where the right common iliac artery compresses the left common iliac vein. The variant exists in a significant portion of the population, but is usually asymptomatic; however, clinically significant stenosis can occur by iatrogenic means. In this report, we describe a patient who presents with left lower extremity pain and swelling. Initial workup for deep vein thrombosis was negative. After being referred to our venous clinic, a magnetic resonance angiography revealed narrowing of the left common iliac vein with a tortuous right common iliac artery crossing over the constriction. During left iliac vein stent placement, a pedicle screw from a prior L2-S1 spinal fusion was noted to be perforated through L5 vertebral body impinging the posterior aspect of the vein. This case demonstrates that increased scrutiny must be applied when dealing with pathology in close proximity to any implanted medical device.

Fluoroscopy-guided pedicle screw accuracy with a mini-open approach: a tomographic evaluation of 470 screws in 125 patients

BACKGROUND

Transpedicular screws are currently placed with open free hand and minimally invasive techniques assisted with either fluoroscopy or navigation. Screw placement accuracy had been investigated with several methods reaching accuracy rates from 71.9% to 98.8%. The objective of this study was to assess the accuracy and safety for 2-D fluoroscopy-guided screw placement assisted with electrophysiological monitoring and the inter-observer agreement for the breach classification.

METHODS

A retrospective review was performed on 125 consecutive patients who underwent minimally invasive transforaminal lumbar interbody fusion and transpedicular screws placement between the levels of T-12 and S-1. Screw accuracy was evaluated using a postoperative computed tomography by three independent observers. Pedicle breach was documented when there was a violation in any direction of the pedicle. Inter-observer agreement was assessed with the Kappa coefficient.

RESULTS

A total of 470 transpedicular screws were evaluated between the levels of T-12 and S-1. In 57 patients the instrumentation was bilateral and in 68 unilateral. A substantial degree of agreement was found between the observers AB (κ=0.769) and A-C (κ=0.784) and almost perfect agreement between observers B-C (κ=0.928). There were a total of 427.33 (90.92%) screws without breach, 39.33 (8.37%) minor breach pedicles and 3.33 (0.71%) major breach pedicles. The pedicle breach rate was 9.08% Trajectory pedicle breach percentages were as follows: minor medial pedicle breach 4.68%, minor lateral pedicle breach 3.47%, minor inferior pedicle breach 0.22%, and major medial breach 0.70%. No intraoperative instrumentation-related or postoperative clinical complications were encountered and no surgical revision was needed.

CONCLUSIONS

Our study demonstrated a high accuracy (90.2%) for 2-D fluoroscopy-guided pedicle screw using electromonitoring. Only 0.71% of the 470 screws had a major breach. Knowing the radiological spine pedicle anatomy and the correct interpretation of EMG are the key factors for this technique.

A new free-hand pedicle screw placement technique with reference to the supraspinal ligament

We sought to compare the safety and accuracy of a new free-hand pedicle screw placement technique to that of the conventional technique. One hundred fifty-three consecutive adult patients with simple fracture in the thoracic or/and lumbar spine were alternately assigned to either the new free-hand or the conventional group. In the new free-hand technique group, preoperative computerized tomography (CT) images were used to calculate the targeted medial-lateral angle of each pedicle trajectory and the pedicle screw was inserted perpendicular to the correspond-ing supraspinal ligament. In the conventional technique group, the medial-lateral and cranial-caudal angle of each pedicle trajectory was determined by intraoperatively under fluoroscopic guidance. The accuracy rate of pedicle screw placement, the time of intraoperative fluoroscopy, the operating time and the amount of blood loss during operation were respectively compared. All screws were analyzed by using intraoperative radiographs, intraoperative triggered electromyography (EMG) monitoring data, postoperative CT data and clinical outcomes. The accuracy rate of pedicle screw placement in the new free-hand technique group and the conventional technique group was 96.3% and 94.2% (P < 0.05), respectively. The intraoperative fluoroscopy time of the new technique group was less than that of the conventional technique group (5.37 seconds vs. 8.79 seconds, P < 0.05). However, there was no statistical difference in the operating time and the amount of blood loss during operation (P > 0.05). Pedicle screw placement with the free-hand technique which keeps the screw perpendicular to the supraspinal ligament is an accurate, reliable and safe technique to treat simple fracture in the thoracic or lumbar spine.

Current concepts and controversies on adolescent idiopathic scoliosis: Part II

A new era in the surgical treatment of adolescent idiopathic scoliosis (AIS) opened with the introduction of pedicle screw instrumentation, which provides 3-column vertebral fixation and allows major deformity correction on the coronal, sagittal, and axial planes. A steep learning curve can be expected for spinal surgeons to become familiar with pedicle screw placement and correction techniques. Potential complications including injury to adjacent neural, vascular, and visceral structures can occur due to screw misplacement or pull-out during correction maneuvers. These major complications are better recognized as pedicle screw techniques become more popular and may result in serious morbidity and mortality. Extensive laboratory and clinical training is mandatory before pedicle screw techniques in scoliosis surgery are put to practice. Wider application, especially in developing countries, is limited by the high cost of implants. Refined correction techniques are currently developed and these utilize a lesser number of pedicle anchors which are strategically positioned to allow optimum deformity correction while reducing the neurological risk, surgical time, and blood loss, as well as instrumentation cost. Such techniques can be particularly attractive at a time when cost has major implications on provision of health care as they can make scoliosis treatment available to a wider population of patients. Pedicle screw techniques are currently considered the gold standard for scoliosis correction due to their documented superior biomechanical properties and ability to produce improved clinical outcomes as reflected by health-related quality-of-life questionnaires. Ongoing research promises further advances with the future of AIS treatment incorporating genetic counseling and possibly fusionless techniques.

Clinically relevant complications related to pedicle screw placement in thoracolumbar surgery and their management: a literature review of 35,630 pedicle screws

OBJECT

The technique of pedicle screw insertion is a mainstay of spinal instrumentation. Some of its potential complications are clinically relevant and may require reoperation or further postoperative care.

METHODS

A literature search was performed using MEDLINE (between 1999 and June 2011) for studies on pedicle screw placement in thoracolumbar surgery. The authors included randomized controlled trials, case-control studies, and case series (≥ 20 patients) from the English-, German-, and French-language literature. The authors assessed study type, the number of patients, the anatomical area, the number of pedicle screws, duration of follow-up, type of pedicle screw placement, incidence of complications, and type of complication. The management of specific complications is discussed.

RESULTS

Thirty-nine articles with 46 patient groups were reviewed with a total of 35,630 pedicle screws. One study was a randomized controlled trial, 8 were case-control studies, and the remaining articles were case series. Dural lesions and irritation of nerve roots were reported in a mean of 0.18% and 0.19% per pedicle screws, respectively. Thirty-two patients in 10 studies (of 5654 patients from all 39 studies) required further revision surgeries for misplaced pedicle screws causing neurological problems. None of the analyzed studies reported vascular complications, and only 2 studies reported visceral complications of clinical significance.

CONCLUSIONS

Pedicle screw placement in the thoracolumbar region is a safe procedure with an overall high accuracy and a very low rate of clinically relevant complications.

Pedicle screw instrumentation and spinal deformities: have we gone too far?

INTRODUCTION

Placement of pedicle screws within the thoracic and lumbar spine has become the "state of the art" for the treatment of spinal deformities. Newly trained surgeons are often trained only with the placement of pedicle screws within the thoracic and lumbar spine and not with hooks or other means of fixation. However, if the benefits of pedicle screw instrumentation in terms of correction ability cannot be questioned on some issues pertaining to their safety, their rationale for all situations as well as their long-term adverse consequence and or early or late complications start to arise.

MATERIALS AND METHODS

We therefore present four case examples that illustrate the advantages, questions and complications inherent to pedicle screw instrumentation in spinal deformities. These four cases serve as discussion supported by a review of the literature. The literature search was performed to include pedicle screws associated risks, costs and complications. Articles focusing on instrumentation of the thoracic and lumbar spine for the treatment of adult and pediatric scoliosis were reviewed.

RESULTS

Pedicle screw instrumentation in the treatment of spinal deformity is here to stay, however a fair number of issues have come up since their widespread use that started 10 years ago: these include their misplacement with the inherent risks to the vascular or neurologic structures, the rate of misplaced pedicle screw not per number of screws inserted, but per patient operated, the number of screws really necessary to achieve a satisfactory outcome while maintaining costs, their contraindications in some very challenging deformities where the risks clearly outweigh their advantage compared to hooks. At last, the use of pedicle screw instrumentation has driven many centers in increasing the safety of such procedures using intraoperative spinal cord monitoring as well as improved imaging technologies.

CONCLUSION

To answer our provocative title "Pedicle screw instrumentation have we gone too far?" Definitively we can answer that for some spinal deformities instrumented with all-pedicle-screw instrumentation, we have observed cases where the surgeons have gone way too far; in other cases, where such instrumentation was used in a comprehensive and rational manner, the answer to "Have we gone too far" is no, and such use of pedicle screw has improved outcome with minimum complications.

Different proximal thoracic curve patterns have different relative positions of esophagus to spine in adolescent idiopathic scoliosis: a computed tomography study

STUDY DESIGN

A computed tomography (CT) study.

OBJECTIVE

To evaluate the changed relative positions of esophagus in proximal thoracic (PT) curves of adolescent idiopathic scoliosis (AIS) patients and analyze the potential risks of esophageal injuries from thoracic pedicle screw (TPS) insertion.

SUMMARY OF BACKGROUND DATA

Translation and rotation of the vertebrae could lead to altered relative positions of surrounding vital structures in AIS patients. The changed positions of aorta and spinal cord in main thoracic (MT) curve have been comprehensively investigated; however, no studies have analyzed the relative position of esophagus in PT curve.

METHODS

Twenty patients with complete proximal thoracic (CPT group) curve, 22 patients with fractional proximal thoracic (FPT group) curve, and 14 normal patients with a straight spine (normal group) were included. Axial CT images from T2 to T5 at the midvertebral body level were obtained to evaluate esophagus-vertebral angle (EVA, defined as 0° when the esophagus was located directly lateral to the left, 90° when strictly anterior, and 180° when directly lateral to the right). The percentages of esophagus in the direction of screw passage were calculated to analyze potential risks of esophageal injuries during TPS insertion.

RESULTS

EVA in the FPT group was significantly smaller than that in the normal group (P < 0.05), whereas EVA in the CPT group was significantly greater than that in the normal group (P < 0.05) at each level. The esophagus was located approximately anterior to the vertebral body in the normal group but shifted anterolaterally to the right in the CPT group and anterolaterally to the left in the FPT group. The esophagus was at a high risk of injury with right anterior penetrated TPS in the CPT group and was at a high risk of injury with left anterior penetrated TPS in the FPT group.

CONCLUSION

Different anatomic patterns of PT curves could cause different altered positions of esophagus relative to spine and result in different potential risks of esophageal injuries during TPS insertion. Spine surgeons should choose appropriate pedicle screw length to avoid anterior cortical perforation in the PT region of AIS patients.

The accuracy of intraoperative O-arm images for the assessment of pedicle screw postion

STUDY DESIGN

Human cadaveric study.

OBJECTIVE

The objective of the study was to determine the accuracy of intraoperative O-arm images in determining pedicle screw position using open dissection as the gold standard.

SUMMARY OF BACKGROUND DATA

Pedicle screws are widely used in the treatment of various spinal disorders. Postoperative computed tomographic scans are the imaging gold standard to detect pedicle screw malposition. However, a second procedure is necessary if such malpositioned screws have to be revised. The O-arm is an intraoperative scanner that allows revision of a screw without having to return the patient to the operating room for a separate procedure. No previous studies have looked at the accuracy of intraoperative O-arm images in determining pedicle screw position.

METHODS

This factorial validation study utilized 9 cadavers in a comparison of intraoperative O-arm images and the dissection gold standard. Four hundred sixteen screws were inserted using 3-dimensional image (O-arm) guidance from C2 to S1. The screw positions were randomized into 3 groups: "IN" (fully contained within the pedicle), "OUT-lateral," or "OUT-medial." After screw insertion, O-arm images were obtained and reviewed in a blinded fashion by 3 independent observers. Dissection identified the true position of the screws. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using dissection results as the gold standard. The interobserver reliability was also determined.

RESULTS

The overall accuracy, specificity, sensitivity, PPV, and NPV of O-arm images for the thoracic and lumbar spine were 73%, 76%, 71%, 74%, and 72%, respectively. Accuracy of surgeon perception in the cervical spine was significantly less than in the thoracic and lumbosacral spine. There was substantial interobserver agreement between the 3 readers.

CONCLUSION

Intraoperative O-arm images accurately detect significant pedicle screw violations in the thoracic and lumbosacral spine but are less accurate for the cervical spine.

A novel computer-assisted drill guide template for thoracic pedicle screw placement: a cadaveric study

INTRODUCTION

The objective of this study was to develop a novel, patient-specific, navigational template for thoracic pedicle screw placement.

METHODS

Twenty thoracic cadaver specimens were randomly divided into two groups of 10: the navigational template group and the free-hand group. A volumetric CT scan was performed on each thoracic vertebra, and a three-dimensional reconstruction model was generated. A drill template was designed with a surface that was the inverse of the posterior vertebral surface. Each drill template and its corresponding vertebra were manufactured using a rapid prototyping technique and tested for violation. Two hundred and forty screws were implanted into the thoracic spines and the positions of the screws were evaluated.

RESULTS

Two hundred and forty thoracic screws were inserted using either the navigational template method or the free-hand method. The accuracy rate and incidence of risk for setting thoracic pedicle screws differed statistically between the two methods (P < 0.05): The navigational template method had a higher accuracy rate and a lower incidence of risk than the free-hand method. Moreover, the free-hand method had a significant learning curve, whereas a learning curve for the navigational template method was not obvious.

CONCLUSION

We have developed a novel, patient-specific, navigational template for thoracic pedicle screw placement with good applicability and high accuracy.

Validity of surgeon perception of navigated pedicle screw position: a cadaveric study

STUDY DESIGN

Human Cadaveric Experimental Study.

OBJECTIVE

To determine the validity of surgeon perception of pedicle screw position inserted using intraoperative three-dimensional (O-arm) image-guided screw insertion.

SUMMARY OF BACKGROUND DATA

A surgeon's ability to detect pedicle wall violations intraoperatively is crucial for optimal pedicle screw placement. Accuracy of use of a probe or sound to assess pedicle breach is not optimal and may require experience. Intraoperative navigation has been shown to improve screw placement accuracy. It has not been shown, however, whether navigation in combination with screw tract palpation can further increase the surgeon's ability to detect a pedicle breach in pedicle screw placement in the cervical, thoracic, and lumbosacral spine.

METHODS

Four hundred eighteen screws were inserted using three-dimensional image guidance transpedicularly from C2 to S1 in 10 fresh frozen cadavers. Screw tracts were created using navigation and then probed. After probing, the surgeon stated whether he perceived that the screw would be in, out laterally, or out medially. After screw insertion for all the levels, open dissection was then performed to determine the actual pedicle screw position. The surgeon's perception of screw position was compared to the dissection results.

RESULTS

The overall specificity, sensitivity, positive predictive value, and negative predictive value of the surgeon perception of pedicle screw position were 87%, 80%, 78% and 88%, respectively. Accuracy of surgeon perception of pedicle screw position was significantly less than in the cervical spine when compared with thoracic and lumbosacral spine.

CONCLUSION

Surgeon perception of a navigated pedicle screw position is accurate in the thoracic and lumbar spine. Detection of pedicle screw violations by surgeon perception in the cervical spine is less accurate and does not reliably lead to accurate screw placement.

Placement of thoracolumbar pedicle screws using three-dimensional image guidance: experience in a large patient cohort

OBJECT

The goal of this study was to analyze the placement accuracy and complications of thoracolumbar pedicle screws (PSs) inserted using 3D image guidance in a large patient cohort.

METHODS

The authors reviewed the charts of 220 consecutive patients undergoing posterior spinal fusion using 3D image guidance for instrumentation placement. A total of 1084 thoracolumbar PSs were placed using either the BrainLAB Vector Vision (BrainLAB, Inc.) or Medtronic StealthStation Treon (Medtronic, Inc.) image guidance systems. Postoperative CT scanning was performed in 184 patients, allowing for 951 screws to be graded by an independent radiologist for bone breach. All complications resulting from instrumentation placement were noted. Using the intraoperative planning function of the image-guided system, the largest diameter screw possible in each particular case was placed. The screw diameter of instrumentation placed into the L3-S1 levels was noted.

RESULTS

No vascular or visceral complications occurred as a result of screw placement. Two nerve root injuries occurred in 1084 screws placed, resulting in a 0.2% per screw incidence and a 0.9% patient incidence of nerve root injury. Neither nerve root injury was associated with a motor deficit. The breach rate was 7.5%. Grade 1 and minor anterolateral "tip out" breaches accounted for 90% of the total breaches. Patients undergoing revision surgery accounted for 46% of the patients in this study. Accordingly, 154 screws placed through previous fusion mass could be evaluated using postoperative CT scanning. The breach rate in this specific cohort was 7.8%. A total of 765 PSs were placed into the L3-S1 levels in this study; 546 (71%) of these screws were > or = 7.5 mm in diameter. No statistical difference in breach rate was noted in PSs placed through revision spinal levels versus nonrevision spinal levels (p = 0.499). Additionally, no increase in breach rate was noted with placement of 7.5-mm-diameter screws.

CONCLUSIONS

Three-dimensional image guidance is a useful adjunct to placement of spinal instrumentation. The complication rate in this study was low, and accurate placement of instrumentation was achieved despite the high percentage of revision surgery cases in our patient population. Additionally, because active fluoroscopy was not used for instrumentation placement, there was minimal to no radiation exposure to the surgeon or operating room staff.

Pneumothorax complicating "in-out-in" thoracic pedicle screw placement for kyphotic deformity correction in a child

The authors describe a rare case of pneumothorax as a complication of thoracic pedicle screw placement in an 11-year-old girl undergoing posterior segmental instrumentation for a kyphotic deformity. Spontaneous pneumothorax after posterior fusion for adolescent idiopathic scoliosis has been reported in the orthopedic literature; however, to the best of the authors' knowledge, pneumothorax directly related to pedicle screw placement for spinal deformity has not been previously described. The authors discuss the anatomical and technical aspects leading to this complication and the lessons learned from it.

Anterior exposures of the pediatric spine and posterior pedicle screw instrumentation

Treatment of spinal deformities, tumors, and trauma is greatly facilitated by correctly understanding the associated anatomy. Exposure of the spine, whether with a standard posterior dissection or a technically demanding costotransversectomy, facilitates surgical treatment of all disorders. When indicated, posterior instrumentation with pedicle screws allows for maximum rigidity and stability until arthrodesis ensues. Appropriate stepwise screw placement and confirmation of placement with radiographs and triggered electromyograms allows safe use of pedicle screws at all regions of the spine, with no associated morbidity to the patient. This article focuses on the classic approaches used to access the pediatric spine and discusses modern-day pedicle screw instrumentation for spinal pediatric deformity, trauma, or tumors.