Spinal fractures in patients with ankylosing spinal disorders: a review

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 ! !!1! 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] Spinal fractures in patients with ankylosing spinal disorders ! !!2! 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. Spinal fractures in patients with ankylosing spinal disorders ! !!3! 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. Tornase 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 Spinal fractures in patients with ankylosing spinal disorders ! !!4! 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 Spinal fractures in patients with ankylosing spinal disorders ! !!11! 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 Spinal fractures in patients with ankylosing spinal disorders ! !!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 Spinal fractures in patients with ankylosing spinal disorders ! !!13! 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. Spinal fractures in patients with ankylosing spinal disorders ! !!14! 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. Spinal fractures in patients with ankylosing spinal disorders ! !!15! 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 Spinal fractures in patients with ankylosing spinal disorders ! !!16! 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, Spinal fractures in patients with ankylosing spinal disorders ! !!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: Spinal fractures in patients with ankylosing spinal disorders ! !!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. Spinal fractures in patients with ankylosing spinal disorders ! !!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, Spinal fractures in patients with ankylosing spinal disorders ! !!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 Spinal fractures in patients with ankylosing spinal disorders ! !!27! 43. Hanson J, Mirza S. Predisposition for spinal fracture in Ankylosing spondylitis. Am J Roentgenol 2000; 174: 150. 44. Thumbikat P, Hariharan RP, Ravichandran G, McClelland MR, Mathew KM. Spinal Cord Injury in Patients With Ankylosing Spondylitis. A 10-Year Review. Spine 2007; 32: 2989-2995. 45. Clark CR (ed). The Cervical Spine. 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Spinal fractures in patients with ankylosing spinal disorders ! !!28! 52. Kanter AS, Wang MY, Mummaneni PV. A treatment algorithm for the management of cervical spine fractures and deformity in patients with ankylosing spondylitis: Neurosurg Focus 2008; 24 (1): E11. 53. Deutsch H, Haid Jr RW. Cervical ankylosing spondylitis, in Mummaneni PV, Lenke LG, Haid Jr RW (eds). Spinal Deformity: A Guide to Surgical Planning and Management. St. Louis: Quality Medical Publishing 2008: 307-330 54. Slone RM, McEnery KW, Bridwell KH, Montgomery WJ. Fixation techniques and instrumentation used in the cervical spine. Radiol Clin North Am 1995; 33: 213-232. 55. Serin E, Karakurt L, Yilmaz E, Belhan O, Varol T. Effects of two-levels, fourlevels, and four-levels plus offset-hook posterior fixation techniques on protecting the surgical correction of unstable thoracolumbar vertebral fractures: a clinical study. Eur J Orthop Surg Traumatol 2004; 14: 1-6. 56. Terezen G, Kuru I. Posterior fixation of thoracolumbar burst fracture: shortsegment pedicle fixation versus long-segment instrumentation. J Spinal Disord Tech 2005; 18: 485-488. 57. Suk KS, Kim KT, Lee SH, Kim JM. Significance of chin-brow vertical angle in correction of kyphotic deformity of ankylosing spondylitis patients. Spine 2003; 28: 2001-2005. 58. Gold RH, Bassett LW, Seeger LL. The other arthritides. Roentgenologic fractures osteoarthritis, erosive osteoarthritis, ankylosing spondylitis, psoriatic arthritis, Reiter’s disease, multi-centric reticulohistiocytosis, and progressive systemic sclerosis. Radiol Clin North Am 1988; 26: 1195-1212. Spinal fractures in patients with ankylosing spinal disorders ! !!29! ! Spinal fractures in patients with ankylosing spinal disorders ! !!30! ! Spinal fractures in patients with ankylosing spinal disorders ! !!31! ! Spinal fractures in patients with ankylosing spinal disorders ! !!32! !