Imaging of lumbar spinal surgery complications

[Imaging Evaluation of Early and Long-Term Complications Associated with the Postoperative Spine]

As the number of spinal surgeries being performed expands, the number of medical imaging procedures such as radiography, CT, and MRI is also increasing, and the importance of their interpretation is becoming more significant. Herein, we present the radiological findings of a variety of complications that can occur after spinal surgery and discuss how effectively and accurately they can be diagnosed through imaging. In particular, this study details the characteristic imaging findings specific to the early and long-term postoperative periods. Early complications of spinal surgery include improper placement of surgical instruments (instrument malpositioning), seromas, hematomas, pseudomeningoceles, and infections in the region surrounding the surgical site. Conversely, long-term complications may include osteolysis around surgical instruments, failure of fusion, adjacent segment disease, and the formation of epidural fibrosis or scar tissue. A precise understanding of the imaging assessments related to complications arising after spinal surgery is crucial to ensure timely and accurate diagnosis, which is necessary to achieve effective treatment.

Society of skeletal radiology position paper - recommendations for contrast use in musculoskeletal MRI: when is non-contrast imaging enough?

The following White Paper will discuss the appropriateness of gadolinium administration in MRI for musculoskeletal indications. Musculoskeletal radiologists should consider the potential risks involved and practice the judicious use of intravenous contrast, restricting administration to cases where there is demonstrable added value. Specific nuances of when contrast is or is not recommended are discussed in detail and listed in table format. Briefly, contrast is recommended for bone and soft tissue lesions. For infection, contrast is reserved for chronic or complex cases. In rheumatology, contrast is recommended for early detection but not for advanced arthritis. Contrast is not recommended for sports injuries, routine MRI neurography, implants/hardware, or spine imaging, but is helpful in complex and post-operative cases.

Direct pseudomeningocele contrast injection for spinal CSF leak localization

CT myelography has been traditionally used to evaluate post-operative paraspinal fluid collections to discern CSF leaking into a pseudomeningocele versus a contained seroma. Rather than performing a lumbar puncture and injecting intrathecal contrast for myelography, we present the first report of direct contrast injection into a post-operative paraspinal pseudomeningocele for CSF leak confirmation and localization. This is a simple procedure that has several advantages over a conventional CT myelogram for the evaluation of post-operative paraspinal fluid collections.

Surgical tool entrapment in a young patient with recurrent lumbar spinal stenosis: a case report

Lumbar spinal stenosis (LSS) is a prevalent cause of leg and back pain. In the youth, LSS is not common and mainly results from hereditary musculoskeletal disorders. Moreover, spinal fusion is a surgical approach to the treatment of LSS. Entrapment of surgical tools due to breakage is a rare yet important phenomenon in such operations. Therefore, neurological sequelae of these events need to be explored. The case was a 24-year-old male complaining of local back pain. Initially, he was diagnosed with LSS at L4 and L5. After the fusion of the vertebrae by the posterior spinal fusion (PSF) method, the patient's pain was resolved. However, the subject complained of worsening local back pain limiting his ability to do routine tasks. A few years later, radiographical evaluations indicated the possible presence of a surgical tool that could not be removed via surgery. During a third operation, the object was removed, and the patient's symptoms recovered. Immediate removal of entrapped surgical objects is necessary due to risks associated with migration and central nervous system damage. Comparing our results to other similar reports, we conclude that in cases of foreign object entrapment, neurological sequelae may be nonexistent or progressively worsen. Also, sequelae emerge either soon after the operation or emerge later. This complicates the diagnosis of such events and the decision of whether to subject the patient to additional neurosurgical operations to remove the tool. These variations may be observed due to the moving of the entrapped tool. Follow-up of neurological sequelae in spinal surgery patients is recommended.

Imaging features of the postoperative spine: a guide to basic understanding of spine surgical procedures

Spinal surgical procedures are becoming more common over the years, and imaging studies can be requested in the postoperative setting, such as a baseline study when implants are used, or when there is a new postoperative issue reported by the patient or even as routine surveillance. Therefore, it helps the surgeon in the appropriate management of cases. In this context, there is increasing importance of the radiologist in the adequate interpretation of postoperative images, as well as in the choice of the most appropriate modality for each case, especially among radiographs, computed tomography, magnetic resonance imaging and nuclear medicine. It is essential to be familiar with the main types of surgical techniques and imaging characteristics of each one, including the type and correct positioning of hardware involved, to differentiate normal and abnormal postoperative appearances. The purpose of this pictorial essay is to illustrate and discuss the more frequently used spine surgical interventions and their imaging characteristics, with an emphasis on classical decompression and fusion/stabilization procedures. KEY POINTS: Plain radiographs remain the main modality for baseline, dynamic evaluation, and follow-ups. CT is the method of choice for assessing bone fusion, hardware integrity and loosening. MRI should be used to evaluate bone marrow and soft tissue complications. Radiologists should be familiar with most performed spinal procedures in order to differentiate normal and abnormal. CRITICAL RELEVANCE STATEMENT: This article discusses the main surgical procedures involved in the spine, which can be didactically divided into decompression, stabilization-fusion, and miscellaneous, as well as the role of diagnostic imaging methods and their main findings in this context.

Symptomatic Postoperative Epidural Hematoma in the Lumbar Spine

A symptomatic postoperative epidural hematoma (SPEH) in the lumbar spine is a complication with variable presentation and the potential to rapidly cause an irrecoverable neurological injury. Significant heterogeneity exists among current case series reporting SPEH in the literature. This review attempts to clarify the known incidence, risk factors, and management pearls. Currently, literature does not support the efficacy of subfascial drains in reducing the incidence of SPEHs and possibly suggests that medication for thromboembolism prophylaxis may increase risk. Acute back pain and progressing lower extremity motor weakness are the most common presenting symptoms of SPEH. Magnetic resonance imaging is the mainstay of diagnostic imaging necessary to confirm the diagnosis, but if not acutely available, an immediate return to the operative theater for exploration without advanced imaging is justified. Treatment of a SPEH consists of emergent hematoma evacuation as a delay in repeat surgery has a deleterious effect on neurological recovery. Outcomes are poorly defined, though a significant portion of patients will have lasting neurological impairments even when appropriately recognized and managed.

Delayed Symptomatic Entrapment and Herniation of Lumbar Nerve Root Due to a Prior Durotomy Defect Initially Misdiagnosed As Arachnoiditis: A Case Report

Incidental durotomies are well-known complications of spine surgery. They are often identified and repaired intraoperatively, with a preference for primary rather than secondary repair. We present the case of a middle-aged male with worsening radicular pain six months after spinal surgery complicated by a durotomy defect. His pain was worse with coughing or standing. Magnetic resonance imaging identified an L3-L5 extradural fluid collection in the lumbar spinal canal and an empty sac sign. Computed tomography lumbar myelogram identified clumping of the cauda equina nerve roots at L2-L3 and an empty sac sign at L4-L5 and L5-S1, concerning adhesions and arachnoiditis. The patient's unusual worsening of symptoms and a history of a durotomy defect with secondary repair led to suspicion of an alternative cause. Surgical exploration identified the left L5 nerve root herniated through the durotomy defect. Reduction of the nerve root herniation with primary repair of the durotomy was performed, and the patient experienced immediate relief that was stable at his one-month follow-up. This case features an unusual presentation of a delayed herniated nerve root through a prior durotomy defect with entrapment. We highlight the importance of a high degree of caution in cases of increased radicular pain following spinal surgery with a known durotomy, particularly when symptoms do not support the clinical presentation of arachnoiditis. Additionally, primary repair of durotomies should be undertaken whenever possible to avoid this potential complication.

Successful fusion versus pseudarthrosis after spinal instrumentation: a comprehensive imaging review

PURPOSE

Following spinal instrumentation and fusion, differentiating between successful arthrodesis and pseudoarthrosis on imaging can be challenging. Interpretation of such examinations requires understanding both the expected evolution of postoperative findings and the subtle indicators of pseudoarthrosis across multiple imaging modalities. Due to this level of intricacy, many clinicians lack familiarity with the subject beyond the more rudimentary concepts.

METHODS

This review provides an in-depth overview of the imaging of the post-operative spine, with particular emphasis on differentiating between pseudoarthrosis and arthrodesis.

RESULTS

A comprehensive overview of imaging of the post-operative spine is given, including the most common imaging modalities utilized, the expected post-operative findings, imaging findings in pseudoarthrosis, and imaging definitions of fusion.

CONCLUSION

Differentiating between pseudoarthrosis and arthrodesis in the postoperative spine is complex, and requires a robust understanding of various findings across many different modalities.

Severity and location of lumbar spine stenosis affects the outcome of total knee arthroplasty

Background

Recent studies have noted that patients with pre-existing lumbar spinal stenosis (LSS) have lower functional outcomes after total knee arthroplasty (TKA). Given that LSS manifests heterogeneously in location and severity, its influence on knee replacement merits a radiographically targeted analysis. We hypothesize that patients with more severe LSS will have diminished knee mobility before and after TKA.

Methods

This retrospective case series assessed all TKAs performed at our institution for primary osteoarthritis from 2017–2020. Preoperative lumbar magnetic resonance image (MRI) with no prior lumbar spine surgery was necessary for inclusion. Stenosis severity was demonstrated by (1) anterior–posterior (AP) diameter of the thecal sac and (2) morphological grade. TKA outcomes in 103 cases (94 patients) were assessed by measuring preoperative and postoperative arc of motion (AOM), postoperative flexion contracture, and need for manipulation under anesthesia.

Results

Patients with mild stenosis did significantly better in terms of postoperative knee AOM. As AP diameter decreased at levels L1–2, L2–3, L3–4, and L4–5, there was a significant reduction in preoperative-AOM (p < 0.001 for each), with a 16 degree decrease when using patients’ most stenotic level (p < 0.001). The same was noted with respect to increased morphological grade (p < 0.001), with a 5 degree decrease for patients’ most stenotic level (p < 0.001).

Conclusion

Severe LSS, which is readily demonstrated by a reduction in the AP diameter of the thecal sac or increased morphological grade on MRI, correlated with a significant reduction in preoperative AOM that was not improved after TKA. Persistent postoperative reductions in AOM may contribute to reduced patient satisfaction and recovery.

Level of evidence: Level 4

A guide to assessing post-operative complications following en bloc spinal resection

En-bloc resection of spinal tumours is a complex procedure with significant morbidity and mortality. The extensive resection leaves a large soft tissue and osseous defect requiring reconstruction. Following en-bloc resection, there may be complications relating to both the removal of the tumour and the subsequent reconstruction. This paper outlines the imaging appearances of the frequently encountered complications in our experience. The primary aim is to improve the confidence of the radiologist when reporting imaging following spinal en-bloc resection, however we believe this is also useful for the spinal and orthopaedic surgeons in assessing the patients following en block resection.

What is the role of incisional vacuum therapy in challenging spinal wounds? A single centre experience

OBJECTIVE

A surgical approach to the treatment of spinal defects and disorders has become more common because of the medical and technological advancements achieved in the last decade. This rising trend in spinal surgeries is associated with adverse events, most notably wound complications. From its introduction, negative pressure wound therapy (NPWT) has proved to be essential in the management of complex wounds and in speeding up wound recovery. The aim of this study is to investigate the use of incisional NPWT in patients undergoing spinal surgery and its role in the prevention of wound complications.

METHOD

This study is a retrospective medical chart review conducted on patients who underwent spinal surgery and received incisional vacuum therapy as part of their treatment. The apparatus was applied intraoperatively following the spinal surgery for all patients included in this study. All surgical procedures were conducted between September 2019 and May 2020. Data entry and analysis were performed between September and October 2020.

RESULTS

A total of five patients' records were reviewed. In our healthcare centre, three patients developed seroma, one developed haematoma, four required revision surgery and one patient required re-operation. There was no wound dehiscence and none of the wounds became infected. Mean length of hospital stay was 11.2 days (standard deviation (SD): 9.5 days) and mean operation time was 333 minutes (SD: 86.4 minutes).

CONCLUSION

There is a scarcity of data on the role of incisional vacuum therapy in the prevention of wound complications associated with spine surgeries. Our study showed promising results for the use of incisional NPWT in the management of spinal wounds. Further research is required in order to enhance wound care by exploiting this potentially beneficial approach.

Imaging Assessment of the Postoperative Spine: An Updated Pictorial Review of Selected Complications

Imaging of the postoperative spine requires the identification of several critical points by the radiologist to be written in the medical report: condition of the underlying cortical and cancellous bone, intervertebral disc, and musculoskeletal tissues; location and integrity of surgical implants; evaluation of the success of decompression procedures; delineation of fusion status; and identification of complications. This article presents a pictorial narrative review of the most common findings observed in noninstrumented and instrumented postoperative spines. Complications in the noninstrumented spine were grouped in early (hematomas, pseudomeningocele, and postoperative spine infection) and late findings (arachnoiditis, radiculitis, recurrent disc herniation, spinal stenosis, and textiloma). Complications in the instrumented spine were also sorted in early (hardware fractures) and late findings (adjacent segment disease, hardware loosening, and implant migration). This review also includes a short description of the most used diagnostic techniques in postoperative spine imaging: plain radiography, ultrasound (US), computed tomography (CT), magnetic resonance (MR), and nuclear medicine. Imaging of the postoperative spine remained a challenging task in the early identification of complications and abnormal healing process. It is crucial to consider the advantages and disadvantages of the imaging modalities to choose those that provide more accurate spinal status information during the follow-up. Our review is directed to all health professionals dealing with the assessment and care of the postoperative spine.

Spine MRI: A Review of Commonly Encountered Emergent Conditions

Over the last 2 decades, the proliferation of magnetic resonance imaging (MRI) availability and continuous improvements in acquisition speeds have led to significantly increased MRI utilization across the health care system, and MRI studies are increasingly ordered in the emergent setting. Depending on the clinical presentation, MRI can yield vital diagnostic information not detectable with other imaging modalities. The aim of this text is to report on the up-to-date indications for MRI of the spine in the ED, and review the various MRI appearances of commonly encountered acute spine pathology, including traumatic injuries, acute non traumatic myelopathy, infection, neoplasia, degenerative disc disease, and postoperative complications. Imaging review will focus on the aspects of the disease process that are not readily resolved with other modalities.

Gray-Scale Sonography of the Spinal Cord in Postlaminectomy Patient

Laminectomy, a common neurosurgical procedure that decompresses the spinal cord, is the definitive surgical treatment for spinal epidural abscesses. Although complications after laminectomy occur infrequently, they can cause significant morbidity and health care resource usage. These complications include soft tissue collections like a persistent and/or new abscess or a hematoma. The preferred method of diagnosis for spinal soft tissue collections is magnetic resonance imaging. However, traditional neuroimaging poses significant challenges in patients with spinal hardware due to metallic artifact precluding appropriate visualization of anatomy and pathology. This was a case of a patient with extensive spinal hardware where visualization of the spinal cord by postoperative sonography was made feasible by a lack of bone after a laminectomy. Point-of-care ultrasound, a convenient bedside tool with the ability to detect soft tissue collections easily, was used to monitor for postoperative recurrence of a spinal epidural abscess in this patient. Patients with an intact spine do not have adequate acoustic windows due to posterior vertebral anatomy. In postlaminectomy patients without posterior vertebral structures, sonography may offer a diagnostic modality for postoperative monitoring. Ultrasonographers can employ spinal cord sonography, particularly when the indication for decompressive laminectomy was a localized fluid collection or abscess.

Imaging Evaluation of the Spinal Hardware: What Residents and Fellows Need to Know

We provide a comprehensive review of the purpose and expected imaging findings of different types of spinal instrumentation. We also demonstrate the imaging evaluation for optimal positioning and assessment of hardware failure.

Delayed symptomatic spinal adhesive arachnoiditis after surgery for thoracolumbar flexion-distraction injury: A case report

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First description of delayed spinal adhesive arachnoiditis after spine trauma surgery.

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Titanium instrumentation produces less artifacts make MRI a useful to evaluate operated lesions.

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Gabapentin can be the treatment of good option for delayed adhesive arachnoiditis.

Background

Adhesive arachnoiditis is an uncommon lesion caused by an inflammatory reaction in spinal nerves. Reports of substantial symptomatic thoracolumbar (TL) adhesive arachnoiditis after spinal surgery are rare. To the best of our knowledge, this is the first presentation of delayed adhesive arachnoiditis with cauda equina syndrome after decompression and fusion for a traumatic TL flexion-distraction injury.

Presentation of case

A 51-year-old man presented to the emergency room with absence of lower extremity muscle power and partial sensation preservation below T12 after slipping. Magnetic resonance imaging (MRI) and computed tomography demonstrated a flexion-distraction injury at T12-L1 and unstable burst fracture at L1 with posterior fragment displacement and cauda equina compression. Emergency decompression, fracture reduction, and posterior fusion with pedicle screw instrumentation (T11-L2) were performed. After the surgical wound completely healed, the patient was transferred to the rehabilitation department. Three months after surgery, the patient complained of severe pain around the anal and testis area and had absent anal sensation and sphincter tone. We re-evaluated the spine MRI and diagnosed the patient with adhesive arachnoiditis in the previous injury site. After gabapentin was administered, the symptoms dramatically subsided.

Conclusion

To the best of our knowledge, this is the first description of delayed spinal adhesive arachnoiditis after TL spinal surgery due to trauma. Developments in technology and resolution and the fact that titanium instrumentation produces less artifacts make MRI a useful tool to evaluate previously operated lesions. Gabapentin may be a good option in the treatment for delayed-onset postoperative adhesive arachnoiditis.

Instrumentation Removal following Minimally Invasive Posterior Percutaneous Pedicle Screw-Rod Stabilization (PercStab) of Thoracolumbar Fractures Is Not Always Required

BACKGROUND

Percutaneous stabilization for spinal trauma confers less blood loss, reduces postoperative pain, and is less invasive than open stabilization and fusion. The current standard of care includes instrumentation removal.

OBJECTIVE

1. Reporting patient outcomes following minimally invasive posterior percutaneous pedicle screw-rod stabilization (PercStab). 2. Evaluating the results of instrumentation retention.

METHODS

A prospective observational study of 32 consecutive patients receiving PercStab without direct decompression or fusion. Baseline data demographics were collected. Operative outcomes of interest were operative room (OR) time, blood loss, and length of hospital stay. Follow-up variables of interest included patient satisfaction, Numeric Rating Scales for Back and Leg (NRS-B/L) pain, Oswestry Disability Index (ODI), and return to work. Clinical outcome data (ODI and NRS-B/L) were collected at 3, 12, 24 months and continued at a 24-month interval up to a maximum of 8 years postoperatively.

RESULTS

81.25% of patients (n = 26) retained their instrumentation and reported minimal disability, mild pain, and satisfaction with their surgery and returned to work (mean = 6 months). Six patients required instrumentation removal due to prominence of the instrumentation or screw loosening, causing discomfort/pain. Instrumentation removal patients reported moderate back and leg pain until removal occurred; after removal, they reported minimal disability and mild pain. Neither instrumentation removal nor retention resulted in complications or further surgical intervention.

CONCLUSIONS

PercStab without instrumentation removal provided high patient satisfaction, mild pain, and minimal disability and relieved the patient from the burden of finances and resources allocation of a second surgery.

Postoperative Spinal CT: What the Radiologist Needs to Know

During the past 2 decades, the number of spinal surgeries performed annually has been steadily increasing, and these procedures are being accompanied by a growing number of postoperative imaging studies to interpret. CT is accurate for identifying the location and integrity of implants, assessing the success of decompression and intervertebral arthrodesis procedures, and detecting and characterizing related complications. Although postoperative spinal CT is often limited owing to artifacts caused by metallic implants, parameter optimization and advanced metal artifact reduction techniques, including iterative reconstruction and monoenergetic extrapolation methods, can be used to reduce metal artifact severity and improve image quality substantially. Commonly used and recently available spinal implants and prostheses include screws and wires, static and extendable rods, bone grafts and biologic materials, interbody cages, and intervertebral disk prostheses. CT assessment and the spectrum of complications that can occur after spinal surgery and intervertebral arthroplasty include those related to the position and integrity of implants and prostheses, adjacent segment degeneration, collections, fistulas, pseudomeningoceles, cerebrospinal fluid leaks, and surgical site infections. Knowledge of the numerous spinal surgery techniques and devices aids in differentiating expected postoperative findings from complications. The various types of spinal surgery instrumentation and commonly used spinal implants are reviewed. The authors also describe and illustrate normal postoperative spine findings, signs of successful surgery, and the broad spectrum of postoperative complications that can aid radiologists in generating reports that address issues that the surgeon needs to know for optimal patient management.^©RSNA, 2019.

Surgical Site Infection as a Risk Factor for Long-Term Instrumentation Failure in Patients with Spinal Deformity: A Retrospective Cohort Study

BACKGROUND

Surgical site infection (SSI) remains a complication of spine deformity surgery. Although fusion/instrumentation failure in the setting of SSI has been reported, few studies have investigated the relationship between these entities. We examine the relationship between early SSI and fusion/instrumentation failure after instrumented fusion in patients with thoracolumbar scoliosis.

METHODS

A retrospective review of a prospectively maintained case series for patients undergoing spine surgery between January 1, 2006, and October 3, 2017. Inclusion criteria included age ≥18 years and surgery performed for correction of thoracolumbar scoliosis. Data collected included various demographic, clinical, and operative variables.

RESULTS

532 patients met inclusion criteria, with 20 (4%) experiencing SSI. Diabetes mellitus was the only demographic risk factor for increased SSI (P = 0.026). Number of fused levels, blood volume loss, and operative time were similar between groups. Fusion/instrumentation failure occurred in 68 (13%) patients, 10 of whom (15%) had SSI, whereas of the 464 patients with no fusion/instrumentation failure, only 10 (2%) had SSI (P < 0.001). Of the 20 patients with SSI, 10 (50%) had fusion/instrumentation failure, whereas in the 512 patients with no infection, only 58 (11%) had fusion/instrumentation failure (P < 0.001). Patients with infection also experienced significantly shorter time to fusion/instrumentation failure (P = 0.025), higher need for revision surgery (P < 0.001), and shorter time to revision surgery (P = 0.012).

CONCLUSIONS

Early SSI significantly increases the risk of fusion/instrumentation failure in patients with thoracolumbar scoliotic deformity, and it significantly shortens the time to failure. Patients with early SSI have a significantly higher likelihood of requiring revision surgery and after a significantly shorter time interval.

Superiority of Multidetector Computed Tomography With 3-Dimensional Volume Rendering Over Plain Radiography in the Assessment of Spinal Surgical Instrumentation Complications in Patients With Cancer

OBJECTIVE

The objective of this study was to compare multidetector computed tomography (MDCT) images with volume-rendered translucent display (VRTLD) series to plain radiographs for evaluating spinal surgical instrumentation after resection and reconstruction for spinal malignancies.

METHODS

In 44 patients with tumor resection and spinal reconstruction, 17 with complications, 3 neuroradiologists evaluated plain radiographs, MDCT images alone, VRTLD images alone, and MDCT images with VRTLD images for identifying complications in 3 categories: subsidence/migration, construct fracture, and screw loosening. Each category was scored as 1 (complications), 2 (no complications), or 3 (not sure), and the minimum score was used for analyses. Clinical/surgical outcomes were the reference standard.

RESULTS

Sensitivity, specificity, and accuracy (95% confidence interval), respectively, were as follows: MDCT/VRTLD, 100%, 100%, 100% (91.96%-100.00%); MDCT alone, 88.24%, 100%, 95.45% (84.53%-99.44%); VRTLD alone, 82.35%, 96.3%, 90.91% (78.33%-97.47%); plain radiographs, 52.94%, 100%, 81.82% (67.29%-91.81%).

CONCLUSIONS

Multidetector computed tomography with VRTLD series seems best for evaluation of spinal instrumentation after tumor resection and reconstruction.

The role of bone SPECT/CT in patients with persistent or recurrent lumbar pain following lumbar spine stabilization surgery

PURPOSE

Despite recent advances in lumbar spine stabilization surgery (LSSS), a high number of patients continue to complain of persistent/recurrent lumbar pain after LSSS. Conventional imaging (plain radiography, CT and MRI) is commonly performed to assess potential lumbar pain generators, but findings are equivocal in approximately 20% of patients. The purpose of this study was to assess the diagnostic performance of ^99mTc-HDP bone SPECT/CT in identifying potential pain generators in patients with persistent/recurrent lumbar pain after LSSS but in whom conventional diagnostic imaging is inconclusive.

METHODS

A total of 187 patients (median age 56 years, 70 men) with persistent/recurrent lumbar pain following LSSS with inconclusive conventional imaging (plain radiography, CT and/or MRI) underwent ^99mTc-HDP bone SPECT/CT and were included in the study. Tracer uptake on SPECT/CT, as an indicator of ongoing or altered osteoblastic activity, was assessed in the lumbar spine stabilization segment(s) and in adjacent segments. Uptake intensity was graded as (1) high (the same as or more than iliac crest uptake), (2) mild (the same as or more than nondiseased vertebral uptake but less than iliac crest uptake), or (3) negative (normal scan). Mild and high uptake were regarded as positive.

RESULTS

In 160 of the 187 patients (85.6%), SPECT/CT showed positive mild or high tracer uptake in the LSSS region. More than half of the patients had abnormal tracer uptake in the stabilized segments (56.7%) and/or in the adjacent segments (55.6%). Although positive stabilized segment findings were commonly seen at <2 years (70.3%) and the rate decreased with time after LSSS, they were seen at >6 years after surgery in 38.2% of patients. In 51.4% of patients, abnormal activity was seen in the adjacent segments <2 years after LSSS, suggesting early/accelerated degeneration after surgery. The proportion of patients with abnormal activity in the adjacent segments increased to 67.3% at >6 years after LSSS (p < 0.05). Positive SPECT/CT findings in the stabilized segments were more frequent in patients with three or more stabilized segments (p < 0.05), but were not more frequent in the adjacent segments. Overall, positive SPECT/CT guided therapy in 64% of patients, which included facet joint/nerve root injections or re-do surgery at active sites and/or adjacent sites.

CONCLUSION

Bone SPECT/CT is a sensitive diagnostic tool for identifying altered osteoblastic activity, which might be a pain generator in patients with persistent/recurrent pain after lumbar surgery especially when conventional imaging is inconclusive.

Spine MR images in patients with pedicle screw fixation: Comparison of conventional and SEMAC-VAT sequences at 1.5 T

BACKGROUND AND PURPOSE

Slice-encoding metal artifact corrections (SEMAC)-view-angle tilting (VAT) sequences have recently been used in clinical protocols to reduce metal artifacts in MR scans of patients with spinal instrumentation. The objective of this study was to compare the SEMAC-VAT sequence with the conventional MR sequence with a low bandwidth turbo-spin echo (TSE) in terms of image quality, visibility of periprosthetic structures, and diagnostic confidence for detection of postoperative complications in patients who underwent pedicle screw fixation at 1.5 T.

METHODS

Seventy patients who underwent pedicle screw fixation between the thoracic vertebrae and the sacrum were included in the study. The MR scans were retrospectively evaluated by two radiologists for signal-to-noise ratio of anatomical structures and size of artifacts, visibility of periprosthetic anatomical structures, and diagnostic confidence for detection of postoperative complications on conventional TSE and on SEMAC-VAT images. Paired t-tests and Wilcoxon signed-rank tests were used for comparisons, and kappa values were used for inter-observer agreement.

RESULTS

SEMAC-VAT images demonstrated significantly fewer metal artifacts, providing improved delineation of most periprosthetic anatomical structures and higher diagnostic confidence for detection of postoperative complications compared with conventional TSE images (p < 0.001). For the spinal canal, however, the visibility of anatomical structures and diagnostic confidence for detection of postoperative complications were better for conventional TSE than for SEMAC-VAT imaging (p < 0.001).

CONCLUSION

In conclusion, although SEMAC-VAT can significantly reduce metal artifact and provide improved delineation of periprosthetic anatomical structures compared to conventional TSE images, TSE is better for spinal canal evaluation. Therefore, it is important to understand the advantages and disadvantages of SEMAC-VAT and to use it properly.

Bone SPECT/CT in Postoperative Spine

Back pain is a common problem and the diagnosis and treatment depend on the clinical presentation, yet overlap between pain syndromes is common. Imaging of patients with chronic back pain in both pre- and postoperative scenarios include radiological, radionuclide, and hybrid techniques. In general, these techniques have their own advantages and limitations. The aim of surgery is to eliminate pathologic segmental motion and accompanying symptoms, especially pain. However, surgical procedures are not without complications and localizing the cause of the pain is often challenging. Radiobisphosphonate bone SPECT/CT is reported to be useful in evaluating benign orthopedic conditions and it often provides valuable information such as accurate localization and characterization of bone abnormalities. In this review, routinely used spinal surgical techniques and procedures are discussed, as well as the acute and delayed complications related to spinal surgery, the role of conventional imaging, and the potential uses of radionuclide bone SPECT/CT to diagnose pseudoarthrosis, cage subsidence, loosening and misalignment, hardware failure, and postoperative infection.

Treatment of lumbar discitis using silicon nitride spinal spacers: A case series and literature review

INTRODUCTION

Septic infection of a lumbar intervertebral disc is a serious disorder which is often difficult to diagnose and appropriately treat because of the rarity of the disease, the varied presentation of symptoms, and the frequency of low-back pain within the overall population. Its etiology can be pyogenic, granulomatous, fungal, or parasitic; its incidence is rising due to increased patient susceptibility and improved diagnostic tools. Conservative treatments involve antibiotics, physical therapy, and/or immobilization. More aggressive management requires discectomy, debridement, and spinal fusion in combination with local and systemic antibiotic administration.

PRESENTATION OF CASES

Presented here are two case studies of lumbar pyogenic discitis associated with Escherichia coli and Candida albicans infections. Both required single-level anterior discectomy followed by spinal fusion using an antimicrobial silicon nitride (Si3N4) spacer for stabilization without instrumentation. Localized antibiotics were used for only one of the patients. Follow-up CT and MRI scans showed that the infections had been resolved with no recurrence of symptoms.

DISCUSSION

Si3N4 is a relatively new spinal spacer material. It was utilized in these two cases because it reportedly provides a local environment which promotes rapid arthrodesis while resisting bacterial adhesion and biofilm formation. It is also highly compatible with X-ray, MRI, and CT imaging modalities. These properties were particularly attractive for these two cases given the patients' histories, presentation of symptoms, and the decision to forego instrumentation.

CONCLUSION

The use of Si3N4 as an antimicrobial spacer may lead to improved outcomes for patients with pyogenic discitis of the lumbar spine.

Previously unreported complications associated with integrated cage screws following anterior lumbar interbody fusion: report of 2 cases

Anterior lumbar interbody fusion (ALIF) is a widely performed surgical treatment for various lumbar spine pathologies. The authors present the first reports of virtually identical cases of complications with integrated screws in stand-alone interbody cages. Two patients presented with the onset of S-1 radiculopathy due to screw misplacements following an ALIF procedure. In both cases, an integrated screw from the cage penetrated the dorsal aspect of the S-1 cortical margin of the vertebra, extended into the neural foramen, and injured the traversing left S-1 nerve roots. Advanced neuroimaging findings indicated nerve root impingement by the protruding screw tip. After substantial delays, radiculopathic symptoms were treated with removal of the offending instrumentation, aggressive posterior decompression of the bony and ligamentous structures, and posterolateral fusion surgery with pedicle screw fixation. Postoperative radiographic findings demonstrated decompression of the symptomatic nerve roots via removal of the extruded screw tips from the neural foramina.

The Degenerative Spine

Degenerative disease of the spine is a leading cause of back pain and radiculopathy, and is a frequent indication for spine MR imaging. Disc degeneration, disc protrusion/herniation, discarhtrosis, spinal canal stenosis, and facet joint arthrosis, as well as interspinous processes arthrosis, may require an MR imaging workup. This review presents the MR imaging patterns of these diseases and describes the benefit of the MR imaging in these indications compared with the other imaging modalities like plain radiographs or computed tomography scan.

Bone SPECT/CT in the postoperative spine: a focus on spinal fusion

Low back pain is a global problem affecting one in 10 people. The management of low back pain varies from conservative to more invasive methods with a spectacular increase in the number of patients undergoing spinal fusion surgery during the last decade. Conventional radiological and radionuclide studies are often used in the assessment of persistent or recurring pain after spinal surgery with several advantages and limitations related to each technique. This article reviews the key contribution of integrated bone SPECT/CT in evaluating patients with persistent or recurring pain after spinal surgery, focusing on spinal fusion. Current literature supports the use of bone SPECT/CT as an adjunct imaging modality and problem-solving tool in evaluating patients with suspicion of pseudarthrosis, adjacent segment degeneration, and hardware failure. The role of bone SPECT/CT in post-operative orthopaedic scenarios is evolving, and this review highlights the need for further research on the role of bone SPECT/CT in these patients.

Should We Check the Routine Postoperative MRI for Hematoma in Spinal Decompression Surgery?

Background

A postoperative magnetic resonance imaging (MRI) is performed as a routine to assess decompression of the spinal cord as well as to evaluate postoperative complications. The purpose of this study is to analyze the efficacy of postoperative MRI for hematoma in spinal decompression surgery.

Methods

Between January 1, 2008 and January 31, 2015, 185 patients who underwent postoperative MRI after spinal decompression surgery were included in this study. We checked the history of the use of an anticoagulant or antiplatelet agent, withdrawal period, blood platelet count, and prothrombin time (international normalized ratio [INR]). We measured the total amount of suction drainage and duration until removal. We retrospectively reviewed the presence of hematoma and thecal sac compression. Postoperative prognosis was evaluated by a visual analog scale (VAS) and the Oswestry Disability Index (ODI).

Results

Hematomas were found on postoperative MRI scans in 97 out of 185 patients (52.4%). Thirty patients had a thecal sac compressing hematoma: 7 in the cervical spine, 1 in the thoracic spine, and 22 in the lumbar spine. The occurrence of hematoma did not show significant difference according to the use of an anticoagulant (p = 0.157). The blood platelet count, prothrombin time (INR), and suction drainage duration did not have a statistically significant correlation with the occurrence of hematoma (p = 0.562, p = 0.506, and p = 0.429, respectively). The total amount of suction drainage was significantly different according to the presence of hematoma (p = 0.022). The total 185 patients had a significant decrease in the postoperative VAS score (p < 0.001), and the diminution of VAS score was not significantly different according to the occurrence of hematoma (p = 0.243). Even in the cases of thecal sac compressing hematoma, the reduction of VAS score was not significantly different (p = 0.689).

Conclusions

Postoperative MRI for hematoma in spinal decompression surgery has little effect on prognosis or management. Therefore, indiscriminate postoperative MRI should be avoided and MRI should be performed depending on the patient's status.

Postoperative computed tomography and low-field magnetic resonance imaging findings in dogs with degenerative lumbosacral stenosis treated by dorsal laminectomy

OBJECTIVES

To describe postoperative computed tomography (CT) and magnetic resonance imaging (MRI) findings in dogs with degenerative lumbosacral stenosis (DLSS) treated by dorsal laminectomy and partial discectomy.

METHODS

Prospective clinical case study of dogs diagnosed with and treated for DLSS. Surgical and clinical findings were described. Computed tomography and low field MRI findings pre- and postoperatively were described and graded. Clinical, CT and MRI examinations were performed four to 18 months after surgery.

RESULTS

Eleven of 13 dogs were clinically improved and two dogs had unchanged clinical status postoperatively despite imaging signs of neural compression. Vacuum phenomenon, spondylosis, sclerosis of the seventh lumbar (L7) and first sacral (S1) vertebrae endplates and lumbosacral intervertebral joint osteoarthritis became more frequent in postoperative CT images. Postoperative MRI showed mild disc extrusions in five cases, and in all cases contrast enhancing non-discal tissue was present. All cases showed contrast enhancement of the L7 spinal nerves both pre- and postoperatively and seven had contrast enhancement of the lumbosacral intervertebral joints and paraspinal tissue postoperatively. Articular process fractures or fissures were noted in four dogs.

CLINICAL SIGNIFICANCE

The study indicates that imaging signs of neural compression are common after DLSS surgery, even in dogs that have clinical improvement. Contrast enhancement of spinal nerves and soft tissues around the region of disc herniation is common both pre- and postoperatively and thus are unreliable criteria for identifying complications of the DLSS surgery.

Successful Treatment of a Symptomatic Discal Cyst by Percutaneous C-arm Guided Aspiration

Although discal cysts are a rare cause of low back pain and radiculopathy. Currently, surgical excision is usually the first-line treatment for discal cysts. However, alternative treatment methods have been suggested, as in some cases symptoms have improved with interventional therapies. A 27-year-old man presented with an acute onset of severe pain, and was found to have a discal cyst after an open discectomy. The patient underwent cyst aspiration and steroid injection through the facet joint under C-arm guidance. After the procedure, the patient's pain improved to NRS 0-1. On outpatient physical examination 1 week, and 1 and 3 months later, no abnormal neurological symptoms were present, and pain did not persist; thus, follow-up observation was terminated. When a discal cyst is diagnosed, it is more appropriate to consider interventional management instead of surgery as a first-line treatment, while planning for surgical resection if the symptoms do not improve or accompanying neurologic deficits progress.