tese02 - Repositório Aberto · DISH is diagnosed when flowing ossification of the anterior longitudinal ligament is present on spine radiographs over at least four consecutive levels2,14

Dedicatória

Este trabalho é dedicado às pessoas que sempre estiveram ao meu lado,

acompanharam, apoiaram e acima de tudo acreditaram em mim: em primeiro lugar, e

principalmente, a minha mãe (Paula Silva), o meu irmão (João Sampaio), os meus tios

(Lucas Silva que teve um papel fundamental na elaboração deste trabalho, Olívia

Silva e Inês Silva) e os meus amigos.

Dedico também a duas pessoas que foram e serão sempre exemplos de carácter e

dignidade e estiveram sempre presentes na minha vida: os meus avós Ana e Manuel

da Silva.

Spinal fractures in patients with ankylosing spinal disorders

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Spinal fractures in patients with ankylosing spinal disorders: a review

Fracturas vertebrais em doenças anquilosantes da coluna: revisão

Ana Sofia da Silva Sampaio (Faculty of Medicine of University of Oporto)

Orthopedics Department - Hospital de São João, Faculty of Medicine of University of

Oporto

Alameda do Professor Hernâni Monteiro 4900-319 Porto, Portugal

[email protected]


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Spinal fractures in patients with ankylosing spinal disorders: a review

Abstract

Spinal fractures in patients with ankylosing spinal disorders (ASD), such as

ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH), are

unique and have only been described in relatively small case series.

This review aims to clarify the epidemiology and to describe the spine fracture

characteristics, mechanisms of fractures, clinical features, current treatments and their

results and complications in patients with ASD by collecting data previously

published in the literature.

Spinal fractures in patients with ASD are uniquely complex in nature and require

considerable scrutiny and aggressive surgical management to optimize spinal stability

and functional outcomes. It is necessary to propose an improvement of the clinical

problem-solving algorithm to systematically assist spine surgeons in their efforts to

provide optimal surgical management in this difficult patient population.

Patients with spine fractures and ASD are at high risk for complications and death and

should be counseled accordingly. Multilevel posterior segmental instrumentation

allows effective fracture healing. Fractures of the spinal column in patients with AS

and DISH are sufficiently similar to be considered together in terms of institutional

diagnostic and treatment protocols and future research endeavors.

Resumo

Fracturas vertebrais em doenças anquilosantes da coluna são únicas e foram descritas

em relativamente poucos estudos.


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Esta revisão tem como objectivos clarificar a epidemiologia e descrever as principais

características das facturas vertebrais, os mecanismos de fractura, a apresentação

clínica, os tratamentos actuais e seus resultados e complicações nas doenças

anquilosantes da coluna, como a espondilite anquilosante e hiperostose esquelética

difusa idiopática (DISH), através da recolha de informação previamente publicada na

literatura.

Fracturas vertebrais em doenças anquilosantes da coluna são complexas na sua

natureza, requerendo, portanto, uma avaliação minuciosa e um tratamento cirúrgico

agressivo para que se possa melhorar a estabilidade e os resultados funcionais. Torna-

se então necessário que se proponha um algoritmo de abordagem e tratamento que

permita aos cirurgiões uma melhor e sistemática conduta terapêutica.

Pacientes com fracturas vertebrais e doenças anquilosantes da coluna apresentam um

elevado risco de desenvolvimento de complicações e de morte e devem ser

aconselhados eficientemente. Instrumentação segmentar posterior em vários níveis

vertebrais permite a cura efectiva. Fracturas da coluna vertebral em paciente com

espondilite anquilosante e DISH são suficientemente semelhantes para serem

consideradas conjuntamente em termos de diagnóstico e futuras investigações.

Keywords: Spinal Fractures; Ankylosing Spinal Disorders

Palavras-chave: Fracturas Vertebrais; Doenças Anquilosantes da Coluna


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1) Introduction

Ankylosing spondylitis (AS) is the prototype of the spondyloarthropathies, a group of

inflammatory diseases that also includes reactive arthritis, psoriatic arthritis and the

arthritis associated with inflammatory bowel disease. Their shared clinical features

include arthritis of the axial skeleton (sacroiliac joints and spine), oligoarticular

arthritis of peripheral joints and enthesitis (inflammation at sites where tendons,

ligaments and joints capsule insert onto bone)1.

The ankylosed spine is prone to fracture even after trivial trauma2,3. Several

authors2,4,5 have shown patients with ankylosing spondylitis to have a fourfold

fracture risk during their lifetime compared to unaffected individuals. It can be

associated with impaired balance, osteoporosis and a reduced ability to take protective

measures during the fall. Due to multilevel bony fusion long lever arms develop in the

spinal column on which forces can act during trauma2,6. As the disease progresses the

spine becomes increasingly susceptible to injury, eventually even after low energy

impacts2,7-9. Fractures in the ankylosed spine are often unstable due to the ossification

of supportive and elastic soft tissues and may cause neurologic deficit as a result of

dislocation2,10,11. The initial skeletal vertebral trauma can often be missed

predisposing the patient to secondary neurological injury12. Moreover, because of

unstable fracture configurations, initially intact patients may sustain secondary

neurologic deterioration after unprotected transfers and manipulation. Inadequate

awareness of these injuries and inappropriate management, both in the pre-hospital

and in the hospital setting can have devastating consequences12, therefore these

patients should be handled with great care when a fracture is suspected.

Diffuse idiopathic skeletal hyperostosis (DISH) is a supposedly non-inflammatory

disease in which spinal longitudinal ligaments and entheses slowly become ossified


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leading to decreased mobility of the affected region until complete ankylosis

follows2,13. DISH is diagnosed when flowing ossification of the anterior longitudinal

ligament is present on spine radiographs over at least four consecutive levels2,14. Its

etiology is unknown but the associations with obesity, type-2 diabetes mellitus and

advanced age have been demonstrated by several authors2,15,16. It was also speculated

that patients with DISH are at risk for spinal fractures after minor impacts,

comparable to the fracture mechanism of ankylosing spondylitis patients2,13,17.

This review aims to collect data previously published in the literature in order to

systematize the knowledge about the epidemiology, clinical features, mechanisms of

fractures in patients with ankylosing spinal disorders (ASD), clinical management,

surgical treatment and complications of trauma and treatment. For this, a literature

search was performed using “spine fractures” and “ankylosing spinal disorders” as

terms MESH in a database (Pubmed). The survey was limited to the last 5 years and

to papers written in English. This led to 10 articles, however a few reference papers,

older than 5 years, were also used in the review. The information thus gathered was

organized so as to meet the objectives proposed for this work.

2) Epidemiology

AS typically develops in younger males (male:female ratio of 3:1) starting in their

third or fourth decades of life and has been estimated to affect between 0.1% and

1.4% of the general population18. DISH is most commonly observed in individuals

over the age of 50 years with a reported prevalence between 2.5% and 28%18-20.

Acknowledging that DISH is associated with traits typical of modern affluent

societies such as increasing life expectancy, obesity and type 2-diabetes, its


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prevalence and degree of expression can be expected to increase in the next

decades2,21,22.

In patients with ASD, fractures of the spinal column were diagnosed in 19.6% of the

patients, affecting more men (86.6%) than women (13.4%) and more patients with

DISH than with AS23. Whang et al.18 supported that patients with ASD are actually at

greater risk for fractures of the spine after a fall (AS, 83.3%; DISH, 72.2%). The

average age at the time of occurrence was 69 years (range 21 to 98 years)23. The fact

that the age of onset of fracture is later than the age of onset of spinal cord injuries

was not expect to be seen too, since one is the consequence of another. The cervical

spine was involved in 55 to 83.3% of the cases, affecting more patients with AS

(81.2%) than with DISH (60.0%)2. 66.7% of cervical injuries occurred between the

C5 and C7 levels18 and with decreasing frequency toward the lower regions (21% in

the thoracic spine, 16% in the thoraco-lumbar spine and 8% in the lumbar spine)23.

Fractures of the thoracic spine affect more patients with DISH while fractures of the

cervical and the lumbar spine affect more patients with AS2.

Hyperextension was the most common injury displacement (89%), representing the

trauma mechanism for 74.4% of patients with AS and 51.2% of patients with DISH2,

with C6-C7 being the most commonly affected23. Nevertheless, in another study18

41.7% were identified as compression burst fractures, affecting AS and DISH patients

equally, whereas 33.3% were classified as either rotational/translational (reported in

more patients with DISH than with AS2) or distraction extension-type injuries. In

patients with AS, the extension-type fractures can appear in every spinal segments

(cervical spine 68.0%; thoracic spine 93.7%; lumbar spine 100%; sacral spine 100%).

The flexion-type fractures affected only the cervical spine (20.0%) as well as rotation-

type (7.0%). The compression-type affected the cervical spine (5.0%) and the thoracic


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spine (6.3%). In DISH patients, extension-type fractures affected the cervical spine

(44.4%) and the thoracic spine (71.4%)2. The compression-type affected all segments

of the spine except the sacral (cervical spine 11.1%; thoracic spine 14.3%; lumbar

spine 50%) as well as the rotation-type fractures (cervical spine 44.4%; thoracic spine

14.3%; lumbar spine 50%). The flexion-type did not affect the patients with DISH2.

8% of patients had more than 1 noncontiguous spinal fracture. There is a relationship

between the fracture type and the fracture level2 but the level of injury was not

correlated with mortality23.

Relatively to the location of the fracture the information in the literature varies. One

of the studies23 states that fractures through the disc space were most common overall

(37%) and were most prevalent in DISH (45%) whereas fractures through the body

were more common in the AS patients (38%). Other studies2,18,24 described that in

patients with DISH, the majority of fractures observed were through the vertebral

body (63.6% of the total number of fractures2), whereas in AS patients, the number of

fractures through the vertebral body equalled the number of fractures through the

intervertebral disc. During the initial stages of AS, most injuries tend to involve the

brittle intervertebral disks but with more advanced disease the bony ankylosis also

extends across the disk spaces, which may lead to fractures propagation into the

vertebral bodies as well.

The majority of patients sustained low-energy trauma (65.8% of patients with AS and

69.1% of patients with DISH) causing their fracture; a ground-level fall was the most

common mechanism (39%). High-energy impacts caused a fracture in 31.0% of

patients with AS and in 23.6% of patients with DISH2. Which explains the increased

susceptibility of these patients to spinal fractures and spinal cord injuries.


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Retrospective case series25-28 of spinal cord injuries in patients with AS suggest that

1.5-2.0% of patients with such injuries also have an AS prevalence and incidence

(11.4 times25,26) that are much higher than in the general population. A higher

incidence of cervical spinal cord injury has also been noted in the population with AS

(84%)25,26 compared to the general spinal cord-injured population (55%)25,29. Patients

with AS or DISH who present with fractures are more likely to suffer severe

neurological damage than patients with normal spines who present with fractures,

reaching 75% with neurological damage in some series of cervical fractures3,30-33.

Murray and Persellin34 found that 57% of AS patients who sustained spinal fractures

suffered severe neurological injury compared with 18% of patients with previously

normal spines30. Patients with AS who sustain a spinal cord injury are older than the

general spinal cord-injures population, with a mean age from 55 to 61 years25-28,35

compared with a mean age of 37 in the spinal cord-injured population at large25,36.

There was no obvious correlation between the severity of the neurologic deficit and

subsequent mortality in any of these groups18. It has been shown that, AS patients are

more likely to present neurologic deficits after spinal injuries than those with

DISH18,37. Unfortunately, in a large percentage of these cases, the correct diagnosis is

not established until after the patient has already experienced a decline in neurologic

function13,18,38. Initial examination of the patients revealed that nearly half of the AS

group was classified as having complete spinal cord injuries (41.2% ASIA A),

whereas a similar proportion of the individuals with DISH were found to be

neurologically intact (44.4% ASIA E)18. This information was corroborated by

Westerveld et al.2, as, at time of admission, 67.2% of patients with AS had

neurological deficit (ASIA A-D) versus 40.0% of patients with DISH. Overall, more

than 80% of patients with ASD were classified as having excellent or good outcomes


9

according to Odom criteria, suggesting that the majority of these individuals had

experienced a return to their baseline level of function18. However, according to

Westerveld et al.2, secondary deterioration of neurological status was observed in

13.9% of AS patients and in 14.5% of DISH patients in the post-treatment phase and

in a few patients in the follow-up phase.

3) Why ankylosing spondylitis increases the risk of vertebral fracture?

AS transforms the flexible spinal column into a stiff rod39 as the spine in the patient

with AS fuses through paravertebral ligamentous and surrounding soft tissues

ossification and syndesmophytosis, creating a rigid hyperkyphotic deformity and a

global loss of elasticity25. This leads to a spine that resembles a tubular long bone

rather than a dynamic system of multiple parts30 that cannot bear normal loads in

comparison with a healthy spine39 and is incapable of appropriately dissipating the

energy of a traumatic event. These pathologic changes serve to compromise the

biomechanical properties of the spine which combined with the brittle quality of the

osteoporotic bone in patients with AS and a variable degree of peripheral joint

arthritis greatly increase susceptibility to vertebral column factures, even after minor,

often trivial, trauma25-27,40,41 (an odds ratio of 7.7 for clinically significant vertebral

column fractures, as compared with the rate in the general population40). These factors

also exacerbate gait unsteadiness and thus increase susceptibility to falls25. Beyond

these, some authors have evaluated other risk factors associated with vertebral

fractures in the population with AS, reviewed by Geusens et al.42, and these factors

include sex (men more than women), age, low body mass index, disease duration,


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increased restriction of spinal movement and increased occiput-to-wall distance (as a

surrogate measure of kyphosis).

4) Fracture diagnosis

A delay in diagnosis is likely to be multifactorial in its origin. Westerveld et al.2

observed that in 17.1% of the total AS population, the fracture was not diagnosed

within 24h following trauma. Caron et al.23 reported an incidence of delay in

diagnosis up to 5%. This delay happens for three reasons. First, in patients with AS,

vertebral fractures often develop in the background of trivial trauma, and thus the

physician’s index of suspicion may not appropriately rise. Second, patients with AS

commonly have both acute and chronic back pain, and the appropriate fracture

diagnosis can be overlooked by attributing axial pain to normal disease activity. In

52.5% of AS patients the fracture was not timely recognized by the physician (“doctor

delay”), while 47.6% of the AS patients delayed their decision to seek medical

attention (“patient delay”). In 9.1% of patients with DISH the diagnosis was delayed

by failure to identify the fracture, thus representing 100% doctor’s delay. Third, given

the highly abnormal structure of the vertebral column in patients with AS, spinal

fracture diagnosis can be difficult on the basis of plain radiographs alone25.

Radiographic comparison of AS and DISH regarding fracture patterns revealed no

differences between either disease entity. In comparative analysis of clinical variables,

patients with AS experienced a statistically higher likelihood of delay in diagnosis and

to be treated surgically23.

As a delay in diagnosis of fractures in patients with ASD often occur, all available

radiological tools should be used in order to validate the diagnosis39. Imaging of the


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spine must be obtained prior to the initiation of any intervention in patients with AS

who are suspected of having a spine lesion, particularly in a trauma setting.

Unfortunately the ability to conduct an accurate assessment of the spine is often

restricted in these patients, and additionally, the techniques required to obtain

adequate images may place them at risk for additional injury. If the supine position is

intolerable because of pain or risk to neurological status, the right decubitus position

is acceptable or a pillow can be used to raise the pelvis and lower the head. X-rays

(anteroposterior, lateral and oblique views) of the injured region may not reveal the

fracture, giving only indirect information, such as widening of the risk space and

discontinuity of the ossified paraspinal ligaments which is not able to set the

diagnosis39, 43. Diagnosis can also be difficult due to pre-existing spinal alterations39.

In Sapkas et al. study39, the initial radiological study was negative for a spinal fracture

in 60% of patients. Therefore it is concluded that it is necessary to resort to other

methods of diagnosis. Then screening of the entire spinal column with advanced

neuroimaging (MRI or CT) has been recommended. The use of CT scanning and MRI

scanning has been shown to increase the sensivity of initial radiographic assessment.

CT scans were used to elucidate the detail of fracture, deformity and surrounding

fixation sites. MRI scans are very sensitive in picking up soft tissue injuries, to

provide ligamentous detail and reveal any complicating factors that might mitigate or

amplify surgical urgency (such as an epidural hematoma)39,44. The above imaging

techniques (CT and MRI) offer valuable help in revealing the type of fracture. This

definition is important because the stability of the spine, the management of the injury

and the possible complications are related to the type of fracture39. The severe

deformities in these patients often require special imaging reconstructions to allow the

surgeon to properly visualize the spinal canal and other critical structures such as the


12

vertebral pedicles at the apex of the deformity. Specifically, the ability to obtain 2D

and 3D reconstructions in multiple anatomical planes on both CT and MR images

allows physicians to assess spinal anatomy more accurately in patients with such

complicated pathological entities32,45-47. However, MRI cannot be recommended as a

first line investigation in the patient with AS, but add important information in

difficult cases39,44.

To make a proper diagnosis and avoid delays in diagnosis or undiagnosed fractures it

is recommended a sequence of diagnostic methods with increasing sensitivity to turn

the suspicion in certain and propose an appropriate treatment. Accordingly, CT should

be used to image the spinal column whenever a patient with AS presents with

symptoms of new neck or back pain, no matter how minor or trivial the reported

mechanism of injury25. Meticulous review of imaging of the lower cervical and

cervical-thoracic junction is essential because the majority of fractures and

deformities occur in this region in patients with AS30,48.

A misdiagnosed fracture can possibly lead to pseudarthrosis or Andersson lesion

(inflammatory involvement of the intervertebral discs by spondyloarthritis), vertebral

corrosion, collapse and deformity39,49. Delay in diagnosis can also adversely affect a

patient with fracture in ASD and has been reported with variable frequency using a

number of different definitions. Delay in diagnosis has been reported to be associated

with neurological complications in 19.5% to 100% of patients23 .

5) Clinical management

Conservative treatment either by prolonged bed rest in traction or in a cervical collar,

or by early realignment and immobilization in a halo vest has been advocated because


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of supposed higher mortality after surgery31,39. However, maintaining reduction is a

major concern for conservative treatment because it has led to secondary dislocation

and neurological deterioration. Poor bone quality, vulnerable skin, and difficulty in

achieving good alignment are additional arguments against the use of a halo39,50. Also,

the halo vest may not be well tolerated by individuals with AS or DISH, who not only

tend to be older with multiple medical comorbidities but may also exhibit poor

respiratory function because of their underlying disease18.

However, a number of these spinal injuries that were not associated with significant

spinal instability, significant ligamentous disruption or neurologic compromise were

successfully treated conservatively with either a rigid cervical collar or a halo-vest

orthosis18,30. So, the immobilization may be considered in these cases. However, it is

imperative that these individuals be closely monitored to ensure that there is no

subsequent loss of reduction or secondary neurologic deterioration18. As a result,

many clinicians recommended early surgery, particularly in the case of spinal

fractures30.

Rowed27 recommended against traction prior to placement of the halo vest because it

is not required for reduction in AS patients and the risk of distraction with resulting

neurological deterioration and the high risk surgical2 are thus avoided. It is possible

that a return to halo traction or a longer period of bed rest after application of the halo

vest would have obviated a need for surgical stabilization. It is also apparent that,

even with the additional stability provided by halo vest, anterior decompressive

surgery should probably always be combined with stabilization, either posteriorly or

anteriorly, as better methods of anterior fixation evolve27.


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In Westerveld et al. paper2, conservative treatment was performed in 45.8% of

patients with AS and in 45.5% of DISH patients. During the post-treatment phase and

at follow-up, most of the patients demonstrated no change in neurological function.

Given the high incidence of spinal fractures and consequently spinal cord injuries

(SCI) and the increased morbidity and mortality rates in patients with ASD who suffer

an SCI, it is critical that these patients be actively engaged in primary prevention

strategies to avoid this devastating complication of their disease process. Patients with

ASD should be encouraged to install activity aids such as handrails beside all

staircases and within bathrooms, to use night lights in bedrooms and bathrooms and to

avoid loose area rugs that present a tripping risk7,51. Excessive use of alcohol should

be avoided, as should all contact sports or other high-impact physical activities. Seat

belts should be worn at all times while driving, and car seat headrests should be used

liberally. Clearly, the trade-off in terms of restricting certain aspects of daily living far

outweighs the devastating morbidity and death that accompany SCI in patients with

ASD25,26.

6) Surgical treatment

Patients with these injuries represent a unique challenge to spine surgeons because the

majority of these fractures often result in neurological deficits that demand early and

aggressive surgical management to enable neural decompression, spinal stability and

optimal functionality7,52,53. Yet no standardized treatment algorithm exists that

approaches this challenging pathological entity in a systematic, logical and concise

manner52.


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It is generally assumed that stabilization of cervical fractures is better performed with

anterior and posterior support of the spine, especially where implant loosening is a

considerable problem39,41. The failure of support is present mainly in cases where only

anterior or only posterior stabilization was applied because the stabilizing system may

not be able to confront the forces which act on it. Nevertheless, in everyday practice

posterior stabilization is usually performed. The posterior approach allows the

surgeon to recreate the pre-existing alignment of the spine, confer stability to the

injured segment and complete an extensive decompression of the neural elements if

necessary. Besides this, the posterior approach is preferred in order to reduce the

possible causal factors of intra-operative and postoperative complications, taking into

consideration that most of these patients have cardiovascular and pulmonary disorders

caused by restrictive ankylosis of the thoracic cage and prolonging the operating time

by performing double stabilization and thoracotomy aggravates cardiovascular

function. Moreover, the anterior approach to the cervical-thoracic junction is

extremely difficult in these patients due to the great inclination and the kyphosis that

exists at the region39. If anterior bone apposition is accomplished, posterior spinal

fusion (PSF) can be performed, with a second stage anterior spinal fusion (ASF) if

there is persistent spinal deformity. The approach for realignment and stabilization of

cervical fractures depends on fracture site and location; anterior fractures were treated

anteriorly, posterior fractures posteriorly and circumferential 3-column injuries via

360º fixation52. Single-stage 360º fusion in the medically stable patient avoids the

added risk of multiple anesthetic interventions, although at the cost of a slightly

higher risk of infection52,54. Long stabilizing systems that offer support to a greater

area of the spine and the parallel use of braces postoperatively have been proposed in


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order to strengthen the stabilization39. Some authors39,55,56 showed that the fixation is

improved with a higher number of posterior fixation levels .

If anatomic access is limited because of a pronounced deformity, prolonged cervical

traction and/or an anterior wedge release via osteotomy or osteoclasis can be

performed to restore craniocervical alignment52,53,57. Still, it is not recommended any

attempts to improve upon the preinjury sagittal alignment of these patients in the

acute setting because aggressive manipulation may result in an unstable spinal

construct that may subject the spinal cord or nerve roots to further harm.

Consequently, osteotomies and other corrective procedures should be delayed until

the original injury has resolved so that they may be performed in a more controlled

fashion52.

Posterior instrumentation in the cervical spine is usually placed into the lateral mass

due to the small pedicle size and encasement of the often aberrant vertebral artery.

Thoracic and lumbar spine hardware is typically placed in a transpedicular fashion

under fluoroscopic guidance. Given the anatomy bone distortion secondary to the

underlying disease process, the typical landmarks are often obscured, making

hardware placement a unique challenge in patients with AS. Detailed knowledge and

familiarity with lateral mass and pedicle anatomy is essential for the extrapolation of

limited recognizable landmarks during hardware placement and trajectory infiltration.

Posterior instrumentation must be supplemented with bone graft material to ensure

construct and fusion longevity. This is typically performed with local bone harvested

from the spinous processes or lamina, rib autograft or iliac crest autograft that have

successful documented fusions. If cervical osteotomies are required, they are

preferentially performed at C-7 and T-1 due to the absence of the vertebral artery in

the foramen transversarium and the enlarged spinal canal at these levels. Additionally,


17

if iatrogenic spinal cord injury occurs at or below C-7, at least partial upper extremity

function would be preserved52.

Patients who present with spinal deformity, as well as those with delayed injuries

should be placed in light cervical traction (<5 Lbs) to attempt fracture reduction and

spinal realignment. It is recommended to avoid traction weights over 5 Lbs because

sudden, uncontrolled distraction of the cervical spine may occur with heavier

weights52. Although low-weight traction may be employed for selected cervical

lesions to facilitate angular correction and postural positioning with wedge inserts

may be useful for addressing any sagittal plane abnormalities associated with

thoracolumbar injuries. The application of any type of distraction force is strictly

contraindicated in these clinical scenarios because of the increased risk of

precipitating a secondary neurologic insult at the level of an unstable spinal segment,

particularly in the cervical spine18.

In Westerveld et al. study2, surgical treatment was performed in 54.2% of AS patients

and in 54.5% of DISH patients and consisted mainly of posterior fixation. In AS

patients posterior procedures were more often combined with decompression of the

spinal cord than in patients with DISH. In the surgical group 59.4% of AS patients

showed no change in neurological function within the first 3 months versus 76.7% of

DISH patients. At follow-up the majority of patients had the same degree of

neurological deficit they had in the post-treatment phase; 73.3% of AS patients and

90.9% of DISH patients. Improvement of neurological status was described in 27.3%

of AS patients and 6.7% of DISH patients in the post-treatment phase and in 26.7% of

AS patients and 9.1% of DISH patients at follow-up2. In most articles the rationale

behind the treatment strategy was not described but reasons often reported were:


18

deterioration of neurological status, unstable fracture configuration and the presence

of an epidural haematoma.

In the majority of cases the definitive treatment (whether surgical or nonoperative) did

not influence the outcome of neurological status. Overall, surgical treatment seemed

to lead to neurological improvement in more AS and DISH patients than conservative

treatment; both in the post-treatment phase and at follow-up. Most patients improved

one or more than one ASIA scale2. However, this information seems to be

controversial, since another study27 argues that the conservatively managed patients

had generally better outcomes at final follow-up examination than did those managed

surgically, with 64% experiencing good to excellent recovery. Better outcomes in this

group do not necessarily indicate that nonsurgical management is superior, since the

groups are not necessarily comparable. Surgical decompression in a deteriorating

patient appears often to be followed by a poor result, and patients who are

neurologically unstable at the time of surgery seem more likely to deteriorate as a

result of surgery. Anterior decompressive surgery must be advised for the patient who

is deteriorating neurologically with a demonstrated epidural haematoma or disc

herniation, but it is difficult to escape the conclusion that, even with great care and

with continuous intraoperative monitoring, the probability of good recovery is poor. It

may be preferable for the patient who is deteriorating neurologically because of

recurrent dislocation to continue bed rest in the halo vest or possibly halo-pelvic

fixation to arrest the progression of deficit, resorting to early surgical stabilization

only if this strategy fails. Despite the appeal of early internal fixation, surgical results

do not justify an aggressive approach to early surgery as routine management27.


19

7) Complications

When a fracture happens in a patient with AS, it should be considered as high-risk

injury, especially when it is located in the cervical-thoracic junction of the spine. The

most unstable types are shearing fractures39. They may have severe neurological

symptoms or may lead to haemothorax, rupture of the aorta39, aortic pseudoaneurysm

and tracheal rupture2, which are serious complications. Secondary neurological

aggravation may be possible due to displacement of the fractured segments, which

happens mainly in hyperextension injuries18,39. Most of these complications were

lethal2. The percentages of complications (84%23) and mortality are high. The primary

determinant of mortality was the patient age, which also correlated with the number of

comorbidities23. Murray and Persellen34 refer that the mortality rate of patients who

undergo an early operation fluctuates between 15% and 50%. Moreover, patients

managed conservatively have a high mortality rate equal to 25%39,58.

The adverse events that were reported18 after surgical intervention included an

epidural hematoma requiring open evacuation, an anterior cerebral artery infarction,

and aspiration pneumonia. Caron et al.23 discovered that there is an equivalent risk of

epidural hematoma in patients with DISH and AS. The adverse events noted after

operative intervention included constructs that needed revision for loose

instrumentation, wound infection addressed with irrigation and debridement and

myocardial infarction18. Besides these uncommon findings, general complications

such as deep venous thrombosis and respiratory insufficiency were frequently

reported complications in both AS and DISH patients2. The conservative management

of these spinal injuries was also associated with a number of complications such as a

progressive kyphotic deformity, the death of patients from unknown causes after an

extended hospital course, multisystem organ failure and pulmonary insufficiency,


20

which may have been exacerbated by his treatment with halo-vest orthosis18. In

Whang et al. study18 83.3% of patients treated with immobilization or operative

treatment were noted to have excellent outcomes according to Odom criteria whereas

only 16.7% of the subjects who had been treated surgically were classified as having a

poor outcome. The overall complication rate for the DISH group was 41.7%18. In

some articles2, complications (whether fatal or not) may not have been fully reported.

Based on the data provided, however, the complication and mortality rate seemed to

be higher in conservatively treated patients than in surgically treated patients.

Patients should be monitored for neurological outcome, radiographic fusion, and

complications. Postoperative follow-up examinations must be performed at intervals

of 6 weeks, 6 months, and annually thereafter, with radiographic evaluations,

including CT scans obtained immediately postoperatively and again at the 6 and 12

month follow-up examinations. Dynamic flexion-extension radiographs must be

performed at all follow-up visits52.

These findings suggest that individuals with AS or DISH who are victims of spinal

trauma are not only older but also seem to have more serious medical comorbidities

than others who sustain these types of injuries. Not surprisingly, these groups seem to

have higher rates of complications and mortality related to their injuries, which may

necessitate treatment and rehabilitation strategies that are considerably different from

those typically used to treat patients without bony diatheses18.

8) Conclusion


21

The incidence of spinal fractures in patients with AS and DISH is much higher than in

general population as well as SCI. Hyperextension is the most common cause of

spinal fracture in these patients.

Fractures in patients with ASD represent a major diagnostic challenge and it may take

a long time to establish a definitive diagnosis. When this fracture is misdiagnosed, the

risk of neurological damage, other complications and death increase. The delay in

diagnosis happens because vertebral fractures often develop after a trivial trauma, the

axial pain is frequently attributed to normal disease activity and the structure of the

vertebral column is high abnormal in these patients. Thus, protocols for diagnosis are

needed and all available radiological tools should be used in order to validate the

diagnosis.

Since conservative treatment can lead to more complications than surgical treatment,

the surgical treatment has higher success rates. There is still no consensus regarding

the type of approach for surgery. Posterior approach is less dangerous and

straightforward, so it is the approach preferred by most surgeons. Long stabilizing

systems offer greater support to the spine than short constructs.

An improvement of the clinical problem-solving algorithm to systematically assist

spine surgeons in their efforts to provide optimal surgical management in this difficult

patient population is needed.

Although the information about DISH patients is less than about AS patients,

fractures of the spinal column in patients with AS and DISH are sufficiently similar to

be considered together in terms of institutional diagnostic and treatment protocols and

future research endeavors.


22

9) Acknowledgements

This review could not have been written without Dr. Nuno Neves who not only served as my

supervisor but also encouraged and challenged me throughout my academic program. He

guided me through the survey process, never accepting less than my best efforts. Thank you.

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