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

Pedicle Screw Placement in Pediatric and Adolescent Spinal Deformity Surgery: Does Tapping of the Pedicle Screw Tract Increase Safety?

INTRODUCTION

Since the development of pedicle screw fixation in the spine, safe placement has remained a crucial component in maximizing patient outcomes and mitigating pedicle screw-related complications. The purpose of this study is to investigate the utility of pedicle tapping in identifying pedicle breaches.

METHODS

A pediatric spine surgery database was queried to identify a consecutive series of patients who underwent spinal deformity surgery utilizing pedicle screw fixation between May 2019 and October 2022. A "breached pedicle" was defined as a pedicle with intact walls after initial manual cannulation but found to have a breach upon probing after tapping 1 mm smaller than the planned screw diameter. The number of screws placed and breached was prospectively recorded, along with patient demographics and procedural data.

RESULTS

There were 288 patients (68% female) with a mean age of 14.3 years (range: 3.7 to 23.3). Diagnoses included idiopathic (129), neuromuscular (76), syndromic (38), congenital (23), kyphosis (9), spondylopathy (12), and trauma (1). The mean upper and lower instrumented vertebrae were T3 and L3, respectively, with an average of 1.4 posterior column osteotomies (PCOs) (range: 0 to 8). Posterior spinal fusion and segmental instrumentation (PSFSI) was the most common procedure (254 cases, 88%). Of 4796 attempted screw placements, 20 (0.4%) pedicles were breached: medial (17), lateral (1), inferior (1), and inferolateral (1). Fourteen screws were abandoned, 3 redirected, and 3 replaced by hooks. T1 (14.3%) and T6 (1.2%) had the highest breach rates. No associations were found between breached pedicles and age ( P =0.099), sex ( P =0.795), or PCOs ( P >0.05). Congenital scoliosis had the highest breach rate at 1.6%.

CONCLUSION

A total of 4796 pedicle screws were placed, with 1 of every 250 (0.4%) of pedicle screw insertions (n=20) having "breached pedicles" identified only after tapping. The technical step of pedicle screw tapping potentially mitigated the chance of a misplaced pedicle screw. Surgeons need to assess the value of this information in their surgical workflow and risk assessment.

LEVEL OF EVIDENCE

Level III.

What is the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian adolescent idiopathic scoliosis patients with major main thoracic curves? A computed tomography scan analysis of 6,494 pedicles

BACKGROUND CONTEXT

Patients with adolescent idiopathic scoliosis (AIS) have higher prevalence of abnormal or dysplastic pedicles.

PURPOSE

To investigate the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian AIS patients with major main thoracic curves.

DESIGN

Retrospective study.

PATIENT SAMPLE

A total of 6,494 pedicles in 191 patients were measured and evaluated.

OUTCOME MEASURES

The primary outcomes measures were the pedicle width measurements (total transverse pedicle width, transverse cancellous width, total transverse cortical width) and classification of pedicles. Demographic data (age, gender, height, weight, body mass index), proximal thoracic Cobb angle, main thoracic Cobb angle and lumbar Cobb angle were also obtained.

METHODS

AIS patients with major (largest Cobb angle) main thoracic curves and had computed tomography (CT) scans prior to corrective spine surgery were reviewed. The pedicles were classified as Grade A: cancellous channel >4 mm; Grade B: cancellous channel 2 to 4 mm; Grade C: cancellous channel <2 mm or corticalized pedicle >4 mm; Grade D: corticalized pedicle ≤4 mm. Grades B, C, and D were dysplastic pedicles while grades C and D were narrow dysplastic pedicles.

RESULTS

The prevalence of dysplastic pedicles (grades B, C, and D) was 61.7%. There were 22.6% narrow dysplastic pedicles (grades C and D) and 4.1% fully corticalized pedicles (grade D). In the thoracolumbar region, there was a sharp transition from larger and less dysplastic pedicles at T11 and T12 to narrower and more dysplastic pedicles at L1 and L2 (narrow dysplastic pedicles at T11: 3.1%, T12: 3.1%, L1: 39.8% and L2: 23.6%). Higher prevalences of narrow dysplastic pedicles were located at right T3 to T5 (71.2%-83.7%) and left T7-T9 (51.3%-61.2%). Higher prevalences of fully corticalized pedicles were located at right T3 to T5 (20.9%-34.0%) and left T7 to T8 (11.0%-12.0%). These were the concave pedicles of proximal thoracic and main thoracic curves, respectively.

CONCLUSION

There were 95.9% pedicles with cancellous channels (grades A, B, and C) can allow pedicle screw fixation and only 4.1% fully corticalized pedicles (grade D) that require an alternative method of fixation. For grade C pedicles (18.5%), pedicle screws can still be attempted with caution. Precautions should also be observed at the L1 and L2 levels as there was a transition to narrower pedicles.

Comparison of differences and random errors in pedicle diameter measurements between MRI and CT: observational study of 315 pedicles in Lenke type 1 adolescent idiopathic scoliosis patients

BACKGROUND CONTEXT

Posterior spinal fusion with pedicle screws is commonly used for the treatment of adolescent idiopathic scoliosis (AIS). To reduce radiation exposure, methods other than computed tomography (CT) are desirable for preoperative determination of pedicle diameter.

PURPOSE

Investigate the differences between magnetic resonance imaging (MRI) and CT measurements of pedicle diameter.

STUDY DESIGN

Cross-sectional research.

PATIENT SAMPLE

Twenty-one AIS Lenke type 1 patients (19 female and 2 males, mean age at surgery: 15.4 years) who underwent posterior spinal fusion between April 2009 and October 2019.

OUTCOME MEASURES

Gap between CT and MRI pedicle diameters.

METHODS

The inner and outer diameters of the right and left pedicles from T1 to L3 were measured separately by two spine surgeons for statistical comparisons.

RESULTS

The respective minimum and maximum CT-MRI values were -3.7 mm and 4.7 mm for inner diameter and -4.6 mm and 5.3 mm for outer diameter. Regarding inter-examiner error, the probability of a 2 mm difference in measurement was less than 5% for both modalities. The probability of a 1 mm difference was also less than 5%, and that of a 3 mm or more difference was 2.1% for the inner diameter and 2.9% for the outer diameter. Whereas low body weight was significantly associated with measurement differences, pedicle laterality was not.

CONCLUSIONS

MRI does not have the reliability to measure pedicle size in AIS patients at present. However, with advancements in image processing technology, the accuracy of pedicle size measurement by MRI may soon improve.

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.

Preoperative Assessment of the Feasibility of Pedicle Screw Insertion at the Proximal Thoracic Curve in Lenke Type 2 Idiopathic Scoliosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To investigate the feasibility of inserting pedicle screws in the proximal thoracic (PT) curve in Lenke type 2 idiopathic scoliosis, using post-myelography computed tomography (CT).

METHODS

Post-myelography CT images of 46 Japanese patients, 10 to 30 years old, who underwent surgery for Lenke type 2 idiopathic scoliosis were analyzed. A new parameter "SAPS" (space available for pedicle screw) was introduced, which defines the minimal distance between the lateral cortex of the pedicle and the spinal cord, with a SAPS <4.5 mm being "unacceptable." All 460 pedicles (T2 through T6) were analyzed. Pedicle diameter was classified according to the Akazawa grading system.

RESULTS

Most pedicles on the right side at T3 (84.8%) and T4 (97.8%) were unacceptable. The unacceptable rate was 58.7% and 15.2% on the right side at T5 and T6, respectively. A larger Cobb angle of the PT curve was associated with a greater incidence of unacceptable SAPS at these levels. For a Cobb angle of the PT curve >40°, most right T5 pedicles were unacceptable. On the left side, most pedicles from T2 to T5 were acceptable. When T5 was the caudal end vertebra of the PT curve, the left T6 pedicles had an unacceptable SAPS in some cases. When the width of the pedicle channel was ≥2 mm (Akazawa grade 1 or 2), all pedicles from T2 to T6, on both sides, were acceptable.

CONCLUSIONS

Post-myelography CT enabled us to clearly demonstrate the feasibility of inserting pedicle screws in the PT region.

Quantitative comparison of a laterally misplaced pedicle screw with a re-directed screw. How much pull-out strength is lost?

Objective

Redirecting of a laterally misplaced pedicle screw into the accurate position decreases the pull-out strength due to the reinsertion, lateral wall cortical perforation and widening of the pedicle hole. Thus, this biomechanical study was performed to quantitatively analyze the pullout strength of a redirected laterally misplaced pedicle screw into the accurate position.

Methods

Thirty pedicules of 15 bovine vertebrae were separated to 3 groups, according to the screw placement method: 1) standard flawless trajectory; 2) trajectory with lateral pedicle wall perforation; 3) trajectory with lateral wall perforation redirected to the standard trajectory. Samples were placed on a universal testing machine and pullout loads were measured. Kruskal-Wallis test was utilized within 95% confidence interval and p value <0.05 to test for the statistical significance.

Results

The mean pullout strength was 2891±654,2 N(1383-3814,5) in Group 1; 817,8±227,6 N(308,6-1144,9) in Group 2 and 2081,1±487,7 N(1583,5-2962,5) in Group 3. The results found out to be statistically significant (p<0.05). Inter-group comparisons revealed that lateral pedicle wall perforation significantly decreases the pullout strength (p<0.05) and redirection of the screw increases the strength (p<0.05), however it was still weaker than the screws with flawless standard trajectory but this was not statistically significant (p>0.05).

Conclusion

The results of this study confirm that pullout strength of pedicle screw decreases by approximately 71% when the lateral wall is perforated and decreases 28% after redirection to the accurate position.

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.

Safety of Pedicle Screws in Adolescent Idiopathic Scoliosis Surgery

To review existing publications on the safety of pedicle screw insertions in adolescent idiopathic scoliosis (AIS). Despite having increased risk for neurological and visceral injuries, the use of pedicle screws have led to increased correction rates in scoliosis surgery. A review was performed on topics pertinent to pedicle screw insertion in AIS, which included pedicle morphometry in AIS, structures at risk during pedicle screw insertion, and accuracy and safety of various pedicle screw insertion techniques. The importance of computer navigation and future research regarding pedicle screw placement in AIS were also briefly reviewed. Many authors have reported abnormal pedicle anatomy in AIS. Injury to the neural structures was highest over the apical region, whereas aortic injury was the highest at T5 and T10. In the proximal thoracic spine, the esophagus could be injured even with screws as short as 25 mm. Overall pedicle perforation rates for perforations >0 and >2 mm (assessed by computed tomography) ranged from 6.4% to 65.0% and 3.7% to 29.9%, respectively. The critical pedicle perforation (>2 mm excluding lateral thoracic) and anterior perforation (>0 mm) rates was reported to range from 1.5% to 14.5% and 0.0% to 16.1%, respectively. Pedicle perforation rates were lower with the use of computer navigation. The incidence of neurological adverse events after scoliosis surgery was 0.06%–1.9%. Aortic injury has only been observed in case reports. According to the available literature, pedicle screw insertion in AIS is considered safe with low rates of clinical adverse events. Moreover, the use of navigation technology has been shown to reduce pedicle perforation rates.

Zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS): a computerized tomography (CT) review of 1986 screws

PURPOSE

To evaluate the zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS) patients.

METHODS

The scoliosis curves were divided into eight zones. CT scans were used to assess perforations: Grade 0, Grade 1(< 2 mm), Grade 2(2-4 mm) and Grade 3(> 4 mm). Anterior perforations were classified into Grade 0, Grade 1(< 4 mm), Grade 2(4-6 mm) and Grade 3(> 6 mm). Grade 2 and 3 (except lateral grade 2 and 3 perforation over thoracic vertebrae) were considered as 'critical perforations'.

RESULTS

1986 screws in 137 patients were analyzed. The overall perforation rate was 8.4% after exclusion of the lateral perforation. The highest medial perforation rate was at the transitional proximal thoracic (PT)/main thoracic (MT) zone (6.9%), followed by concave lumbar (6.7%) and convex main thoracic (MT) zone (6.1%). The overall critical medial perforation rate was 0.9%. 33.3% occurred at convex MT and 22.2% occurred at transitional PT/MT zone. There were 39 anterior perforations (overall perforation rate of 2.0%). 43.6% occurred at transitional PT/MT zone, whereas 23.1% occurred at concave PT zone. The overall critical anterior perforation rate was 0.6%. 5/12 (41.7%) critical perforations occurred at concave PT zone, whereas four perforations occurred at the transitional PT/MT zone. There were only two symptomatic left medial grade 2 perforations (0.1%) resulting radiculopathy, occurring at the transitional main thoracic (MT)/Lumbar (L) zone.

CONCLUSION

Overall pedicle perforation rate was 8.4%. Highest rate of critical medial perforation was at the convex MT zone and the transitional PT/MT zone, whereas highest rate of critical anterior perforation was at the concave PT zone and the transitional PT/MT zone. The rate of symptomatic perforations was 0.1%.