Fracture in ankylosing spondylitis after minor trauma: radiological pitfalls and treatment by percutaneous instrumentation. A case report

Hounsfield units in assessing bone mineral density in ankylosing spondylitis patients with cervical fracture-dislocation

BACKGROUND

Cervical spine fracture-dislocations in patients with ankylosing spondylitis (AS) are mostly unstable and require surgery. However, osteoporosis, one of the comorbidities for AS, could lead to detrimental prognoses. There are few accurate assessments of bone mineral density in AS patients.

AIM

To analyze Hounsfield units (HUs) for assessing bone mineral density in AS patients with cervical fracture-dislocation.

METHODS

The HUs from C2 to C7 of 51 patients obtained from computed tomography (CT) scans and three-dimensional reconstruction of the cervical spine were independently assessed by two trained spinal surgeons and statistically analyzed. Inter-reader reliability and agreement were assessed by interclass correlation coefficient.

RESULTS

The HUs decreased gradually from C2 to C7. The mean values of the left and right levels were significantly higher than those in the middle. Among the 51 patients, 25 patients (49.02%) may be diagnosed with osteoporosis, and 16 patients (31.37%) may be diagnosed with osteopenia.

CONCLUSION

The HUs obtained by cervical spine CT are feasible for assessing bone mineral density with excellent agreement in AS patients with cervical fracture-dislocation.

Management of Thoracolumbar Vertebral Fractures and Dislocations in Patients with Ankylosing Conditions of the Spine

Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are bone-forming spinal conditions which inherently increase spine rigidity and place patients at a higher risk for thoracolumbar fractures. Due to the long lever-arm associated with their pathology, these fractures are frequently unstable and may significantly displace leading to catastrophic neurologic consequences. Operative and non-operative management are considerations in these fractures. However conservative measures including immobilization and bracing are typically reserved for non-displaced or incomplete fractures, or in patients for whom surgery poses a high risk. Thus, first line treatment is often surgery which has historically been an open posterior spinal fusion. Recent techniques such as minimally invasive surgery (MIS) and robotic surgery have shown promising lower complication rates as compared to open techniques, however these methods need to be further validated.

Mono-segmental percutaneous screw fixation in the management of AoSpine thoracolumbar type B fracture in patients with ankylosing spondylitis: A new treatment

PURPOSE

To assess the viability and effectiveness of mono-segmental percutaneous screw fixation in the treatment of unstable type B thoracolumbar fracture due to ankylosing spondylitis.

METHODS

We report here all 40 patients treated by mono-segmental screw fixation in this indication, between January 2018 and January 2022, with follow-up at 3 and 9 months. Study variables comprised operating time, length of stay, fusion, stabilization quality, and peri-operative morbidity and mortality.

RESULTS

One patient showed early displacement of rods caused by technical error. None of the others showed secondary displacement of rods or screws. Mean age was 73 years (range 18-93), mean hospital stay 4.8 days (range 2-15), mean operative time 52minutes (range 26-95minutes) and mean estimated blood loss 40ml. There were 2 deaths caused by intensive care unit complications. All patients except those in intensive care were verticalized within 24hours after surgery. Parker score was unchanged for each patient before and after surgery and during follow-up.

CONCLUSION

Mono-segmental percutaneous screw fixation in the treatment of unstable type B thoracolumbar fracture due to ankylosing spondylitis was safe and effective. This study showed that this surgery reduced length of hospital stay, operative time, blood loss and complications compared to open or extended percutaneous surgery, and allowed fast rehabilitation in this vulnerable population.

Reduction and Stabilization of an Extension-Distraction Injury in a Patient with Ankylosing Spondylitis: A Case Report

CASE

The authors reported a case of an 83-year-old man with ankylosing spondylitis throughout the cervical, thoracic, and lumbar spine who sustained a three-column T10 osteoligamentous extension-distraction injury after low-energy trauma. A closed reduction was performed using incremental flexion on a variable flexion-extension table and subsequent stabilization with robotic-assisted percutaneous pedicle screw placement. Postoperative radiographs at 7-month follow-up showed intact implants with adequate alignment with the patient remaining at neurological baseline.

CONCLUSION

A closed reduction method using a variable flexion-extension table with stabilization through percutaneous pedicle screw placement is a safe and appropriate method to achieve spinal realignment in select patients.

Iatrogenic Vertebral Fracture During Intramedullary Nailing for Femoral Fracture: A Case Report

CASE

A 73-year-old woman with advanced ankylosing spondylitis (AS) underwent closed reduction and internal fixation using antegrade intramedullary nailing because of midshaft fracture of her right femur. After the surgery had been performed, a fracture and dislocation at T12-L1 was detected. Therefore, emergency spinal decompression and posterior instrumentation placement from T11 to L5 were then performed.

CONCLUSION

Patients with advanced AS have a high risk of vertebral fracture, so special care must be taken not to transmit excessive stress on the spine for surgical reduction and manipulation of the lower extremity.

Biomechanical Evaluation of the Transcortical and Transpedicular Trajectories for Pedicle Screw Insertion in Thoracolumbar Fracture Fixation for Ankylosing Spondylitis

Background: Ankylosing spondylitis (AS) is a chronic disorder characterized by an imbalance between bone formation and resorption. Spinal fractures often occur after minor trauma in patients with AS. For thoracolumbar fractures, transpedicular screw (TPS) fixation through the posterior approach has been suggested. The cortical bone trajectory (CBT) technique has also been used to prevent screw pull-out in patients with poor bone quality. The aim of current study was to assess the biomechanical characteristics of the TPS and CBT technique in thoracolumbar AS fracture fixation by finite element analysis.

Methods: The three-dimensional finite element models of the AS spine were created. The CBT and TPS methods of screw insertion were used in AS spinal fracture models. An intact AS spine model was considered the control. An axial force and torsion in rotation, flexion/extension and lateral flexion were applied in all models in CBT, TPS, and control groups.

Results: The AS spine showed similar construct stiffness after posterior fixation by CBT and TPS techniques under axial, rotational, and flexion/extension loading conditions. The TPS technique showed better intact stability under all loading conditions. Similarly, the TPS technique provided superior fracture regional stability against axial and rotational loads than did the CBT technique. The maximum von Mises stresses were 1714.4 ± 129.8 MPa and 1208.7 ± 107.3 MPa (p < 0.001), which occurred in the CBT and TPS groups under compressive loading.

Conclusions: The TPS technique provides better biomechanical strength under axial, rotational, flexion/extension, and lateral flexion loading than does the CBT technique. Compared with CBT, TPS is more effective in maintaining the stability of AS thoracolumbar fractures from a finite element analysis perspective.

Imaging features of spinal fractures in ankylosing spondylitis and the diagnostic value of different imaging methods

Background

Our study aimed to characterize the imaging appearance of spinal fractures in ankylosing spondylitis (AS) and identify situations in which the use of magnetic resonance imaging (MRI) is necessary.

Methods

A total of 70 cases of spinal fractures associated with AS were retrospectively enrolled. Two radiologists independently reviewed the preoperative images. The location, type, ligament injury, neurological injury, and epidural hematoma following spinal fractures were assessed.

Results

Only one patient had a vertebral compression fracture, and 69 patients had 77 transverse fractures involving three columns. The most frequent injuries in AS patients were type B3 (N=32, 43.8%) spine fractures, followed by type C (N= 20, 27.4%) spine fractures. There were significant differences in fracture types of the different spine regions (H=14.1, P<0.0001). Most type C spine fractures were located in the lower cervical spine, while most of the type B2 spine fractures were located in the thoracic spine. Transverse fractures were classified as shear or stress type fractures. In total, there were 62 shear fractures and 15 stress fractures. All of the transverse fractures were detected by computed tomography (CT). The accuracy of CT in the diagnosis of the exact anatomic involvement of transverse fractures was significantly higher than that of MRI (χ²=8.36, P=0.014). The anterior longitudinal ligament (ALL) was the most frequently torn ligament. Tears of ossified ligaments were best visualized by sagittal reformatted CT. Lower cervical fractures were more likely to be associated with neurological injury compared with fractures to other regions of the spine (χ²=7.24, P=0.025). There were six epidural hematoma cases, which were only detected by MRI, were found to have fractures of the lower cervical spine.

Conclusions

We recommend a whole-spine CT examination with three-dimensional reconstruction for detecting a suspected fracture in AS patients. In cases with neurological injury, MRI examinations are always mandatory. AS patients with lower cervical spine fractures require further investigation by MRI. Patients with non-lower cervical spine fractures without any neurological deficits do not need to undergo an immediate MRI.

First intention vertebroplasty in fractures within an ankylosed thoracolumbar spinal segment

PURPOSE

To evaluate the outcome of percutaneous vertebral cementoplasty (PVC) as the first-line treatment for traumatic thoracolumbar fractures within an ankylosed spinal segment.

MATERIALS AND METHODS

Thirty-one patients (15 men, 16 women; mean age: 79.2±11 [SD] years; age range: 66-95 years) with thoracolumbar fractures within an ankylosed spine segment without neurological impairment treated with PVC were retrospectively evaluated. All patients were controlled at six weeks and one year after PVC. Ankylosing conditions, fractures sites and types, radiological consolidation, spinal complications were assessed. Anterior/posterior vertebral height ratios were measured before and after PVC. Postoperative pain relief and treatment success (radiological fracture consolidation) rates were considered.

RESULTS

The 31 patients had a total of 39 fractures (19 stable [49%], 20 unstable [51%]) treated with PVC. Primary success rate of PVC (initial fracture consolidation without complication) was 61% (19/31). Seven patients (7/31; 23%) exhibited new fractures, and the secondary success rate of PVC (global fracture consolidation one year after repeat PVC) was 87% (34/39). Global consolidation rates of unstable fractures were 85% (17/20) of treated levels. Pain score was null in 84% patients (26/31) one year after PVC. There were no significant differences between pre-PVC (0.62±0.18 [SD]; range: 0.22-0.88) and post-PVC (0.60±0.18 [SD]; range: 0.35-0.88) vertebral height ratios (P=0.94).

CONCLUSION

PVC conveys a high overall success rate and effectively controls pain in patients with vertebral fractures within ankylosed spine segments.

Is routine MRI of the spine necessary in trauma patients with ankylosing spinal disorders or is a CT scan sufficient?

BACKGROUND

Ankylosing spinal disorder (ASD) patients are at a greater risk for spinal fractures due to osteoporosis and rigidity of the spinal column. These fractures are associated with a high risk of neurologic compromise resulting from delayed or missed diagnoses. Although computed tomography (CT) is usually the initial imaging modality, magnetic resonance imaging (MRI) has been proposed as mandatory to help identify spinal injuries in ASD patients with unexplained neck or back pain or known injuries to help identify noncontiguous fractures. However, some studies have also shown that neurological injury can result from the required patient transfer and positioning for an MRI.

PURPOSE

The purpose of our study was to assess the frequency with which an MRI identified an injury not previously identified with CT, and whether this affected the treatment and outcome of the patient. Secondarily, we attempted to identify clinical or CT findings that may render an MRI particularly useful.

STUDY DESIGN

Retrospective review.

PATIENT SAMPLE

Patients with ASD who sustained acute spine fractures from 2005 to 2015.

OUTCOME MEASURES

Acute fractures identified by CT scan and MRI upon admission; neurologic status upon admission and discharge, mode of injury, type of fracture, and final intervention before and after MRI assessment.

METHODS

A total of 124 patients with a diagnosis of diffuse idiopathic skeletal hyperostosis (DISH) or ankylosing spondylitis (AS) were identified by searching the radiology database of a level I trauma center with diagnosis keywords. Final radiology reports were assessed to determine presence and type of fracture(s) from CT. MRI report was then reviewed to assess if additional fractures or injuries were identified beyond that already known from the CT. Neurologic status upon admission and discharge, mode of injury, type of fracture, and final intervention were determined by inpatient notes and/or operative reports. No source funding or conflict of interest was present pertaining to this study.

RESULTS

In the designated time frame, 124 ASD patients with injuries of the spine were identified who had obtained both a baseline CT and MRI. Six patients (4.8%) had additional injuries on MRI that had not been identified with CT. Four of these six patients had a change in treatment plan (three operative and one nonoperative) based on subsequent MRI findings. These included a (1) C4-5 hyperextension injury, (2) C6-7 hyperextension injury, (3) C7 bony fracture with C5-T4 epidural hematoma, and (4) C5-C6 hyperextension injury treated in a brace. Two of the six patients that had additional injuries identified on MRI had no change in their treatment plan. One patient had an additional lumbar extension injury identified above a previously diagnosed injury on CT, which was managed with a Thoracolumbosacral Orthosis (TLSO) according to the original plan. One patient died who had a known odontoid fracture and a suspected C6-7 hyperextension injury, and was identified on MRI as also having a C3-C4 hyperextension injury and a C2 spinal cord transection.

CONCLUSIONS

In this study, 3.2% (4/124) of patients with ASD who presented to a level I trauma center with an acute spine injury identified with CT required a change in their treatment plan based on subsequent MRI findings. Only one fracture was missed on CT imaging, with the other missed injuries all being either disco-ligamentous hyperextension injuries through mobile discs or intracanal pathology. Our recommendation is that the routine use of MRI be limited to patients with nonankylosed levels in which a disco-ligamentous injury may have occurred, and in patients with neurological deficits that require investigation of the spinal canal to assess for causes of neurological injury.

Spine Fractures in Ankylosing Diseases: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

Review of literature and case series.

OBJECTIVES

Update and review of current treatment concepts for spine fractures in patients with ankylosing spinal disorders.

METHODS

Case presentation and description of a diagnostic and therapeutic algorithm for unstable spinal injuries with an underlying ankylosing spinal disorder (ASD) of the cervical and thoracolumbar spine.

RESULTS

Nondisplaced fractures can be missed easily using conventional X-rays. Thus, computed tomography (CT) scans are recommended for all trauma patients with ASD. In doubt or presence of any neurologic involvement additional magnetic resonance imaging (MRI) scans should be obtained. Spine precautions should be maintained all times and until definitive treatment (<24 h). Nonoperative fracture treatment is not recommended given the mechanical instability of the most commonly seen fracture patterns (AOSpine B- and C-type, M2) in patients with ASD and inherent high risk of secondary neurologic deterioration. For patients with ankylosing spondylitis (AS) or diffuse idiopathic hyperostosis (DISH) sustaining cervical spine fractures, a combined anterior-posterior instrumentation for fracture fixation is recommended. Closed reduction and patient positioning can be challenging in presence of preexisting kyphotic deformities. In the thoracolumbar (TL) spine, a posterior instrumentation extending 2 to 3 levels above and below the fracture level is recommended to maintain adequate reduction and stability until fracture healing. Minimally invasive percutaneous pedicle screws and cement augmentation can help to minimize the surgical trauma and strengthen the construct stability in patients with diminished minor bone quality (osteopenia, osteoporosis).

CONCLUSIONS

Current concepts, treatment options, and recommendations of the German Orthopedic Trauma Society-Spine Section for spinal fractures in the ankylosed spine have been outlined.

Double non-contiguous fractures in a patient with spondylo-epiphyseal dysplasia with spinal ankylosis treated with open and percutaneous spinal fixation technique: a case report

Background

Patients with ankylosing spines are susceptible to developing spinal fractures even with minor trauma and can develop early or late neurological injuries. These fractures require early and aggressive surgical management to enable spinal stability and/or neural decompression. Being highly unstable by nature, they require relatively long segment instrumentation and fusion, which can increase paravertebral soft tissue damage and perioperative bleeding. The purpose of this report is to describe a rare case of traumatic double fractures at the cervico-thoracic and thoraco-lumbar transition zones in ankylosing spine with spondylo-epiphyseal dysplasia (SED) of unknown cause, which were successfully treated with a combined open and percutaneous spinal fusion procedure.

Case presentation

A 46-year-old woman who was diagnosed with non-contiguous fractures in cervico-thoracic and thoraco-lumbar junction zones among multiple injuries sustained in a traffic accident was treated with hybrid techniques for posterior instrumentation with an open approach using a computed tomography (CT)-based navigation system and percutaneous pedicle-screwing method. She regained mobility to pre-admission levels and started walking on crutches 3 months postoperatively. Genetic testing for the cause of SED revealed no mutation in the COL2A1 or TRPVR4 genes. The union of fractured spine was confirmed on CT scan 1 year postoperatively.

Conclusion

This is the first report of double spinal fractures in an ankylosing spine with genetically undetermined spondyloepiphyseal dysplasia. A long-segment posterior instrumentation procedure incorporating the invasive treatment of spinal fractures in ankylosing spondylitis or diffuse idiopathic hyperostosis was effective.

Percutaneous surgery for thoraco-lumbar fractures in ankylosing spondylitis: Study of 31 patients

BACKGROUND

The risk of vertebral fracture is increased 4-fold in patients with ankylosing spondylitis (AS). Diagnostic challenges and the vulnerability associated with AS combine to generate high morbidity and mortality rates. The objective of this study was to assess the outcome of percutaneous thoraco-lumbar fracture surgery in patients with AS, in terms of quality of life, fracture healing, and complications.

HYPOTHESIS

Percutaneous surgery used to treat thoraco-lumbar fractures in patients with AS reliably provides fracture healing, preserves self-sufficiency, and minimises post-operative complications.

METHODS

Two centres included 31 patients with AS who were managed by percutaneous surgery for thoraco-lumbar fractures in 2013-2015. The data were reviewed retrospectively, although admission data were collected prospectively. Clinical outcomes were assessed by comparing the values at baseline and last follow-up of three variables: the Parker score, the visual analogue scale (VAS) pain score, and the EuroQol five dimensions (EQ-5D) quality-of-life score. Computed tomography was performed 1 year after surgery to evaluate bone healing, screw position, and implant loosening. Intra- and post-operative complications were recorded.

RESULTS

The 31 patients had a mean age at surgery of 75.1 years, a mean follow-up of 35.6 months, and a minimum follow-up of 12 months. Three patients died during follow-up. Mean hospital stay duration was 6 days. Cemented screw fixation was used in 18 patients. At last follow-up, all patients had recovered their self-sufficiency; the mean Parker score was 7.14, compared to 6.73 at baseline, the mean VAS pain score was 1.8, and the mean EQ-5D score decrease versus baseline was 0.07 (P=0.02). Bone healing was consistently achieved. Loosening of an uncemented pedicle screw was noted in 1 patient. Of the 228 screws implanted, 6 (2.6%) were improperly positioned, including 1 within the spinal canal in a patient free of neurological manifestations. Asymptomatic cement leakage was noted in 2 patients.

DISCUSSION

Percutaneous fixation of thoraco-lumbar fractures in patients with AS is a reliable method that produces a high healing rate and allows prompt patient mobilisation with preservation of self-sufficiency. The post-operative complication rate is low.

LEVEL OF EVIDENCE

IV, retrospective observational study.

Spinal fractures in patients with ankylosing spondylitis

The ankylosed spine is prone to fracture even after minor trauma due to its changed biomechanical properties. The two central features of ankylosing spondylitis (AS) that promote the pathological remodeling of the spine are inflammation and new bone formation. AS is also associated with osteoporosis that is attributed to an uncoupling of the bone formation and bone resorption processes. Therefore, bone resorption occurs and promotes weakening of the spine as well as increased risk of vertebral fractures which can be hugely different in terms of clinical relevance. Even in the presence of symptomatic clinical vertebral fractures, the diagnosis can be overruled by attributing the pain to disease activity. Furthermore, given the highly abnormal structure of the spine, vertebral fracture diagnosis can be difficult on the basis of radiography alone. CT can show the fractures in detail. Magnetic resonance imaging is considered the method of choice for the imaging of spinal cord injuries, and a reasonable option for exclusion of occult fractures undetected by CT. Since it is equally important for radiologists and clinicians to have a common knowledge base rather than a compartmentalized view, the aim of this review article was to provide the required clinical knowledge that radiologists need to know and the relevant radiological semiotics that clinicians require in diagnosing clinically significant injury to the ankylosed spine.

Management of thoracolumbar spine fractures with neurologic disorder

Thoracic and lumbar fractures represent approximately 50% of neurologic spinal trauma. They lead to paraplegia or cauda equina syndrome depending on the level injured. In the acute phase, the extension of spinal cord lesions should be limited by immediately treating secondary systemic injury factors. Quick recovery of hemodynamic stability, with mean arterial blood pressure>85 mm Hg, appears essential. There is no clinical evidence in favor of high-dose corticosteroid protocols. Their effect on neurologic recovery is unproven, whereas they lead to a higher rate of secondary septic and pulmonary complications. Incomplete deficits (ASIA B-D) require urgent surgery. There is no consensus with regard to complete paraplegia (ASIA A), but early surgery can enable neurologic recovery in some cases. The principle of surgical treatment is based on spinal cord decompression, instrumentation and fracture reduction. Early stabilization of the spine improves respiratory function and shortens the duration of mechanical ventilation and thus intensive care unit stay. Depending on the severity of associated lesions, early surgery within 48 hours is beneficial in polytrauma patients. Percutaneous instrumentation combined with mini-open posterior decompression stabilizes the spine, limiting approach-related morbidity.

Good outcomes of percutaneous fixation of spinal fractures in ankylosing spinal disorders

INTRODUCTION

The ankylosed spine is prone to trauma even with after application of force at low energy levels. Multi-level vertebral bony fusions produce long lever arms, susceptible to fracture, with an increased risk of neurological injury. Additional problems result from delayed presentation and osteoporosis. These patients are also often at high risk of complications, making conventional open spinal surgery less appealing. We present the outcomes of percutaneous fixation and its advantages in this high risk group of patients.

METHODS

A retrospective review of a series of 10 patients with a diagnosis of either ankylosing spondylitis or diffuse idiopathic skeletal hyperostosis (DISH). All patients had sustained a spinal fracture between January 2009 and January 2013 and underwent percutaneous fixation using Medtronic longitude system (Minneapolis, USA) with Polyaxial screws. All were followed up with outcomes, complications and functional scores (Oswestry Disability Index (ODI) and Pain Visual Analogue scores (VAS).

RESULTS

The mean patient age was 68. There was a delayed presentation in seven patients, of which two presented with neurological compromise. The neurological deficit did not change with surgery and there were no neurological complications as a result of surgery. The mean length of stay was 24 days, with no direct surgical complications. The mean drop in haemoglobin level was 2.1, with three patients requiring a blood transfusion. The patients were followed up to a mean of 22 months, with a mean ODI of 16 and pain VAS of 1.1. At the time of follow up, two patients had died with no loss to follow up.

DISCUSSION

Even minor trauma can result in fracture in the ankylosed spine, requiring a high index of suspicion from the physician. The risks of missing such a fracture are significant neurological injury. The biomechanics of the spine are significantly altered, and treatment is demanding. We propose that minimally invasive spinal surgery can achieve good outcomes, low complication rates and high rates of satisfaction.