Aortic Injury by Thoracic Pedicle Screw. When Is Aortic Repair Required? Literature Review and Three New Cases

The optimal introversion angle and length of pedicle screw to avoid L1-S1 vascular damage

BACKGROUND

posterior pedicle screw fixation is common method, one of the most severe complications is iatrogenic vascular damage, no report investigated association of different introversion angles (INTAs) and length of pedicle screw. The aims were to investigate the optimal introversion angle and length of pedicle screw for improving the safety of the operation, and to analyze the differences of vascular damage types at L1-S1.

METHODS

Lumbar CT imaging data from110 patients were analyzed by DICOM software, and all parameters were measured by new Cartesian coordinate system, INTAs (L1-L5:5°,10°,15°,S1: 0°, 5°,10°,15°), DO-AVC (the distance between the origin (O) with anterior vertebral cortex (AVC)), DAVC-PGVs (the distance between AVC and the prevertebral great vessels (PGVs)), DO-PGVs (the distance between the O and PGVs). At different INTAs, DAVC-PGVs were divided into four grades: Grade III: DAVC-PGVs ≤ 3 mm, Grade II: 3 mm < DAVC-PGVs ≤ 5 mm, Grade I: DAVC-PGVs > 5 mm, and N: the not touching PGVs.

RESULTS

The optimal INTA was 5° at L1-L3, the left was 5° and the right was 15° at L4, and screw length was less than 50 mm at L1-L4. At L5, the left optimal INTA was 5° and the right was 10°, and screw length was less than 45 mm. The optimal INTA was 15° at S1, and screw length was less than 50 mm. However, screw length was less than 40 mm when the INTA was 0° or 5° at S1.

CONCLUSIONS

At L5-S1, the risk of vascular injury is the highest. INTA and length of the pedicle screw in lumbar operation are closely related. 3 mm interval of screw length may be more preferable to reduce vascular damage.

Let's think beyond the pedicle: A biomechanical study of a new conceptual extra pedicular screw and hook construct

Background

Transpedicular screws have proven the test of time, yet they are not devoid of complications. Many newer techniques such as 2 D and 3D fluoroscopy,O arm Navigation assisted surgery, robotic assisted surgery have come into existence to the increase precision in pedicle screw insertion. But, complications do occur in their presence. We propose an Extra pedicular screw and hook system (EPSH) system with similar biomechanical property, better safety profile and short learning curve compared to traditional pedicle screw.

Purpose

To Compare the pull out strength of Traditional Pedicle screw Vs Extra pedicular screw and hook system(EPSH).

Methods

Biomechanical testing was conducted according ASTM F543 guidelines to compare the pull-out strength of EPSH based construct and traditional pedicle screw construct. Six saw bone samples in each group considered. Screw of 5.5 mm diameter and length of 35 mm was used in both the groups. Pull out strength assessed by giving 5 mm/min axial load. The axial load Vs displacement of the screw were recorded and plotted. The maximum load required for screw failure is noted in both the group. Statistical analysis was done.

Results

The mean peak load of pedicle screw group was found to be 1670.9 ± 393.2 N with mean displacement at peak load was found to be 13.44 ± 1.7 mm and in EPSH group it was 1416.4 ± 341.4 N and 15.78 ± 3.9 mm respectively. A paired t-test showed no statistical difference(p < 0.05) between 2 groups.

Conclusion

EPSH has shown to have almost similar biomechanical property as that pedicle screw construct. With Addition of the hook, it provides an extra rotational stability as well. Being an extra-pedicular screw it has high safety profile and needs less expertise for insertion.

Tactics for the treatment of potential and true thoracic aorta injuries by pedicle screws in the absence of acute bleeding: analysis of a small clinical series and literature data

Objective. To analyse the results of treatment of patients in whom, after fixation of the thoracic spine, contact of screws with the aorta with its wall injury was revealed.Material and Methods. Three own observations and literature data were analysed.Results. Three patients with potential (1 case) and true (2 cases) injury to the thoracic aorta by a transpedicular screw underwent simultaneous surgical intervention including thoracic endovascular aortic repair (TEVAR) followed by remounting (2 cases) or removal of the transpedicular fixation system. An analysis of publications on this topic is presented.Conclusion. Intramural hematoma caused by screw malposition is an indication for aortic repair due to the risk of its dissection or rupture.It is advisable to give preference to endovascular methods of treating vascular injuries under conditions of local anesthesia as the first stage, and then to perform the revision of transpedicular fixation system under anesthesia.

Different angular kyphosis locations have different relative positions of aorta to spine in patients with Pott's deformity

Background

The position of the aorta relative to the spine in kyphosis secondary to Pott's deformity is little understood. The purpose of this study was to investigate the anatomic relationship between the aorta and the spine in patients with Pott’s deformity and to compare it with the normal people.

Methods

Seventy-six patients with Pott’s deformity (Group TB) and seventy-two age- and sex-matched patients with a normal spine (group NC) were enrolled in this study. The relative position of aorta to the spine was evaluated from T4 to L4 on the computed tomographic angiography scans for controls and at the apex level for TB patient, and was classified into 4 kinds of degrees.

Results

The left pedicle-aorta angle in group TB was significantly larger than that in group NC at the T6-L3 levels. Group TB exhibited significantly smaller left pedicle-aorta distance, pedicular line-aorta distance and vertebra/rib-aorta distance than those in group NC at the T5-T10 levels, but bigger at the L1-3 levels. Patients with grade 3 and 4 aorta had more segments involved compared with those with grade 1 aorta. Patients with grade 2, 3, and 4 aorta showed larger kyphotic angles than those with grade 1.

Conclusions

Patients whose morbid segments involved only thoracic vertebrae presented with an “Ω” shaped aorta in sagittal plane, and 4 different kinds of degrees of aorta relative to the vertebra/rib in axial plane. Patients whose morbid segments covered lumbar vertebrae presented with an “M” shaped aorta in sagittal plane, and the aorta shifted further from apex vertebra but was located in close proximity to the vertebral body at levels above and below the osteotomy levels in axial plane.

Does intraoperative CT navigation increase the accuracy of pedicle screw placement in pediatric spinal deformity surgery? A systematic review and meta-analysis

PURPOSE

Although pediatric spinal deformity correction using pedicle screws has a very low rate of complications, the long-term consequences of screw malposition is unknown. CT navigation has been proposed to improve screw accuracy. The aim of this study was to determine whether intraoperative navigation during pedicle screw placement in pediatric scoliosis makes screw placement more accurate. We also examined radiation exposure, operative time blood loss and complications with and without the use of CT navigation in pediatric spinal deformity surgery.

METHODS

A systematic review of the literature was conducted. After screening, 13 articles were qualitatively and quantitatively analyzed to be used for the review. A random effects meta-analysis using REML methodology was employed to compare outcomes of screw accuracy, estimated blood loss, radiation exposure, and surgical duration.

RESULTS

Screws placed with CT navigation surgery were three times as likely to be deemed "acceptable" compared with screws placed with freehand and 2D fluoroscopy assistance, twice as likely to be "perfect", and only 1/3 as likely to be potentially unsafe (all p value < 0.01). EBL was not significantly different between groups; however, operative time was roughly thirty minutes longer on average. Random effects analysis showed no significant difference in effective dose radiation while using CT navigation (p = 0.06).

CONCLUSION

This systematic review of the literature demonstrates that intraoperative navigation results in more accurate pedicle screw placement compared to non-navigated techniques. We found that blood loss was similar in navigated and non-navigated surgery. Operative time was found to be approximately a half hour longer on average in navigated compared to non-navigated surgery. Effective radiation dose trended higher in navigated cases compared to non-navigated cases but did not reach statistical significance.

Thoracic Endovascular Aortic Repair for Iatrogenic Injury of the Thoracic Aorta

PURPOSE

Address iatrogenic injury to the descending thoracic aorta by breached spinal screws through a novel approach of concomitant spinal screw removal and thoracic endovascular repair (TEVAR) placement.

CASE REPORT

A 36-year-old female with idiopathic scoliosis underwent T4 to L3 bilateral pedicle instrumentation with spinal fusion and correction of scoliosis deformity. Ten months post-operative, she continued to complain of mid-thoracic pain; computed tomography (CT) angiography revealed protrusion of the left T5 and T6 transpedicular screws into her descending thoracic aorta by 3 and 5 mm, respectively. She was taken to the odds ratio (OR) in a combination case with vascular and neurosurgery. Positioned in the right lateral decubitus position, TEVAR was successfully deployed while neurosurgery concurrently removed the invading spinal screws via posterior spinal exposure. Neurosurgery then completely revised the spinal hardware during the same operation. The patient progressed well throughout the remainder of her hospital stay and was discharged on postoperative day 4. Two-year angiography demonstrated a well-placed TEVAR with no extravasation or aortic abnormality.

CONCLUSIONS

In the setting of iatrogenic aortic injury due to pedicle screws, concomitant TEVAR and spinal screw removal is a safe and feasible treatment option that allows for spinal reconstruction to occur without multiple trips to the operating room.

Clinical accuracy and initial experience with augmented reality-assisted pedicle screw placement: the first 205 screws

OBJECTIVE

Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system.

METHODS

A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors' institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion.

RESULTS

Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m2. Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall.

CONCLUSIONS

AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

Aortic injury in spine surgery……What a spine surgeon needs to know

Aortic injury is a rare, yet underreported and underestimated complication of spine surgery. Anatomical relation between the aorta and the spine changes under physiological (positional) as well as pathological (deformity) conditions, which puts the aorta at risk of injury during spine surgery. Clinical presentation of aortic injury ranges from asymptomatic perforation of the aorta to acute fatal bleeding. Although several diagnostic methods have been reported, CT-angiography remains an important diagnostic study. Several advancements in the open and the endovascular surgical management have been reported to be successfully used in the management of aortic injury following spine surgery. Management approach of malpositioned screws abutting the aorta is still controversial. Anatomical knowledge and understanding of the previously reported mechanisms of aortic injury are important to be integrated in the preoperative planning process. If the complication occurs, time-to- recognition and to-appropriate-management are important factors for predicting mortality. If unrecognized and untreated in the acutely injured patients, mortality can approach 100%.

Massive Hemoptysis Caused by an Aortobronchial Fistula Related to Pedicle Screw Impingement

We report a case of a 50-year-old man with a 10-year history of pedicle screw internal fixation in the thoracic spine and heroin abuse, who presented with sudden-onset massive hemoptysis with hemorrhagic shock and asphyxia. Urgent contrast-enhanced chest computed tomography (CT) characteristically showed thoracic aortic perforation, a paravertebral pseudoaneurysm, and an intrapulmonary hematoma. Emergency percutaneous thoracic endovascular aortic repair (pTEVAR) with the preclose technique using a vascular closure device under local anesthesia achieved success without any complications. The current case highlights the importance of understanding massive hemoptysis caused by an aortobronchial fistula related to pedicle screw impingement in clinical practice and the value of pTEVAR with the preclose technique under local anesthesia in the emergency setting.

Malpositioned pedicle screw in spine deformity surgery endangering the aorta: report of two cases, review of literature, and proposed management algorithm

STUDY DESIGN

Case reports and review of the literature with a proposed management algorithm.

OBJECTIVES

To report two cases of a potential vascular complication due to an incorrectly placed pedicle screw (PS) during spine deformity surgery. Relevant literature regarding the management of vascular complications is reviewed, and an evidence-based management algorithm is proposed. Aortic lesions represent a rare but potentially life-threatening complications with spine deformity and revision surgery, significantly increasing the risk. A management algorithm for an aortic lesion in the case of a malpositioned PS has not yet been published.

METHODS

Case 1: An 18-year-old female with proximal thoracic spinal non-instrumented fusion underwent a revision corrective procedure due to a progressive right-sided thoracolumbar compensatory curve. However, postoperative computed tomography (CT) performed to evaluate the position of the PS revealed malposition of the left T9 PS, which was abutting the descending aorta with CT angiography excluding the perforation of the aorta. Case 2: A 17-year-old male was scheduled for correction of Lenke 3-C-N adolescent idiopathic scoliosis. Postoperative routine evaluation with low-dose CT revealed a left T9 PS paravertebral malposition, and subsequent CTA demonstrated that the thread of the PS was in contact with the descending thoracic aorta and an unlikely hemodynamically significant vessel injury.

RESULTS

Successful removal of both malpositioned PS was performed. In the first case, a cardiovascular surgeon attended the operation if an urgent thoracotomy was needed, and in the second case, additional video-assisted thoracoscopic control of the aorta was performed during PS removal.

CONCLUSIONS

Preoperative imaging in spinal surgery is essential to avoid major vascular and other complications when placing PS, especially in thoracic deformities. When a potential major vessel complication emerges, an interdisciplinary approach and an appropriate management algorithm are mandatory to make the best clinical decisions.

LEVEL OF EVIDENCE

4.