Developments in all aspects of spine care over the last few decades have revolutionized the treatment of patients with spine injury and have spawned hope for improved outcomes following these devastating injuries. Spine surgeons are now able to apply molecular, biomechanical, biomaterial, and computer engineering advances to the surgical care of spine patients. In the past, technical and material advances were adopted without sound scientific evidence. This pattern appears to be changing with the recognition of the need for scientific and fiscal accountability anchored in patient-focused outcomes.
Not only has this evidence-based approach been applied to new technology, but it is now being applied to answer questions, such as early versus late decompression for neurologic recovery and operative indications for thoracolumbar trauma. There has been recognition that these questions cannot be definitively answered by one center or institution but can only be addressed through collaboration at a national and often international level between experts in the treatment of spine trauma and study design. This approach allows for the pooling of patient data to potentially address chronically underpowered spine literature.1 This focus issue on spine trauma will provide concentrated information on many of the controversial and evolving areas of spinal trauma care. This article will put some of the epidemiologic, clinical, and research issues influencing spine trauma in a longitudinal perspective, and provide guidance to ensure that philosophies around the betterment of spine trauma care are understood and supported.
Epidemiology of Spinal Cord Injury
Spine trauma encompasses a broad spectrum of pathology, from occiput to sacrum and neurologically intact to complete spinal cord injuries (SCIs). Yet, there is a disproportionate weighting of the literature toward SCIs, especially from an epidemiologic perspective. To the authors’ knowledge, only 1 population-based study has been conducted on spinal column injuries.2 Population-based studies are required to understand the epidemiology because they do not have selection biases that can skew results of observational or experimental studies. The devastating consequences of SCIs will continue to stimulate research; however, with spinal column injuries affecting a higher proportion of the population, there is optimism that more attention will focus on neurologically intact spinal column injuries. For now, much of our detailed information refers to SCIs.
The incidence of SCIs has remained stable over the past 30 years in North America, and ranges between 27 and 47 cases per million population.2–7 The major change has been the increase in the number of individuals with SCIs surviving. In 1970–1971, 38% of individuals with SCIs died before hospitalization,8 and in 1997—2000, this decreased to 15.8%.4 This reduction is attributable to improvements in automobile design, legislation requiring safety measures such as seatbelts, and the care provided at the scene of the injury.9 Higher quality incidence and prevalence data encompassing both column and cord injury will be made available through regionalization of spine trauma care, and the evolution of spine registries and focus groups.
The demographic trends in the SCI population reflect the changes seen in the general population. There has been an increase in the mean age at injury, from 28.6 years in the 1970s to 38.0 years in 2000,10 along with an increase in the proportion of individuals older than 60 years, going from 4.7% before 1980 to 10.9% in 2000. The ratio of men to women with SCIs has decreased slightly because of changes in the workplace, increased participation in high-risk sporting activities, and a higher incidence of osteoporosis in women.10 Demographics suggest that these trends are likely to continue.11,12
The aging North American population will make the assessment of comorbidities integral to the assessment of outcomes in traumatic spine injury. In the trauma literature, it is estimated that between 5% and 37%13,14 of patients have comorbidities. With the increasing incidence of health concerns in all age groups (obesity, diabetes, etc.), comorbidities will become important covariants in the analysis of spinal injury outcomes.15
Motor vehicle crashes have remained the number one cause of SCIs, accounting for approximately 50% of all injuries, followed by falls (21%), violence (11%), sports/recreation (10%), and other causes (8%), respectively.7,8,10,16,17 The only exception was between 1990 and 1999 in the United States, when violence moved ahead of falls to be the second leading cause.16 This peak in violent crimes in the mid 1990s16,18 closely followed the crime rate in the United States,19 and by the year 2000, it had significantly decreased in all age groups.16 The etiology of SCI is different in Canada because acts of violence are not as common, and represented approximately 4% of all cases of SCI between 1997 and 2001.4,20
One of the most noticeable trends is the increase in the overall percentage of spinal injuries resulting from falls in the elderly.16 Fall-induced injuries are a major public health problem in North America and other industrialized nations, especially in individuals older than 80 years.21 Prevention and aggressive medical treatment of osteoporosis may help to stem this trend. There have also been more injuries in thrill-seeking sports such as snowboarding22 and mountain biking, while the percentage of injuries resulting from diving has steadily decreased because of prevention programs and improved swimming pool design.16,23,24 Prospective observational studies that determine the incidence of injury in sports may assist in the development of effective injury prevention programs and design of protective equipment.
Types of Injuries
In 55% of all cases, the cervical spine remains the most common anatomic region for SCI.25 Fatalities caused by occipito-cervical injuries were common in early epidemiologic studies,26 however, improved survival from these injuries is evident by a 2.3% to 6.8% increase in ventilator dependent discharges in the last 30 years.16 Individuals older than 65 years tend to have fewer cervical and more lumbar fractures.27 The severity of injury may also change because older individuals have a lower incidence of SCIs compared to younger adults (3.3% vs. 12.9%, respectively).27 This trend toward less severe injuries is also apparent in adults20 and is likely to continue.25,29
Life Expectancy and Mortality
The life expectancy following SCI is improving but still remains lower than the general population.10,28,30 The adjusted odds of dying for a person with a SCI were 67% lower between 1993 and 1998, compared to between 1973 and 1977.28 This dramatic improvement has resulted from advances in medical and surgical care. Further progress will require integrated well-designed databases with input from a variety of health care providers. Long-term prospective studies will provide health planners and clinicians30 with the necessary information to enhance further survival and health-related quality of life (HRQOL). Causes of mortality have changed, with respiratory infections taking over from genitourinary disease as the primary cause of death.10,30 Evidence-based guidelines for the prevention of thromboembolic disease25 have reduced this as a significant cause of mortality. Reducing the burden of chronic disease and promoting health will be the challenges of the future because heart disease now ranks second as a cause of death in individuals living with SCI.10
Changes in the Treatment of Spine and Spinal Cord Injuries
Spine Trauma Care Systems
There has been tremendous progress in the development of trauma care since the publication Accidental Death and Disability: the Neglected Disease of Modern Society, in 1966,31 which advocated for strong leadership to deal with accidental injury, viewed as a “neglected epidemic.”32 Trauma care has evolved from a local to a regional care system, while broadening the scope to include the continuum from prevention to reintegration into the community.33,34 With the development of these proven cost-effective systems, mortality has been reduced by 10% to 43%.35–40
In spine trauma, there have been similar shifts toward the regionalization of care for spinal cord and spinal column injuries. Spine injuries are relatively uncommon in comparison to other types of trauma; therefore, they would likely benefit from treatment in a comprehensive specialized unit. The first spinal unit treated servicemen that had SCIs during the second World War.42 Since that time, evidence23,43–46 clearly shows fewer complications, decreased length of stay, and improved patient outcome when patients with SCI are treated in a specialized unit.
The regionalization of spine trauma will require support from needs assessments to critically analyze a region’s trauma care system as evidence that can be used to lobby those who allocate resources.47 The advantages of regionalization include: accessing patients for clinical trials, enhancing standardized care, facilitating population-based studies through registries, developing benchmarks for national spinal trauma outcomes, and having the ability to provide timely care when new repair and regeneration interventions become available. Spinal trauma registries must include data on the number of pre-hospital deaths, assess survival measures following hospital discharge (i.e., 30-day survival),35,37,48 and move beyond mortality as a measure of effectiveness and include measures of functional status, use, and HRQOL.37,48
Challenges facing registries include the introduction of stringent privacy legislation in North America requiring approval to use a person’s identifiable health information for research purposes.49 Institutional review boards now frequently require patients to provide informed consent to access their medical record. The inability to collect complete data on all patients with a given condition severely jeopardizes the usefulness of the data because selection biases are introduced, in which registry participants are systematically different than nonregistry participants.50 Some argue that there is a need to waive informed consent for observational research that poses minimal risk to the patient.49,50
Advances in pre-hospital screening have reduced the incidence of misdiagnosis in the field resulting in less neurologic deterioration.51,54 The trend toward improved survival requires proactive consideration of ethical, medical, and resource implications at all levels of the continuum of care. The pre-hospital phase of spine trauma is not without controversy. Currently, in North America, considerable attention is being directed toward the role of immobilization at the scene of injury. The current trend is to reevaluate the role of spinal immobilization, and determine which patients need to be immobilized and how should they be immobilized.55
Over the last decade, there have been changes in the way we assess acute spine trauma from both a screening and evaluative perspective. There are 2 processes that have fueled these changes. First, the speed and accuracy of diagnostic imaging, such as computerized tomography (CT) and magnetic resonance imaging (MRI). Second, the development of evidence-based guidelines for when and how to image suspected and established spine trauma.
Epidemiologic screening principles and issues around access and cost do not allow for the indiscriminant use of medical imaging on every trauma patient. The most controversial questions in this domain involve the imaging of the cervical spine in the patient with minor trauma and in the obtunded poly-trauma patient. The Canadian C-spine Rules,56 a prospective study that developed guidelines for when to obtain plain radiographs in the alert trauma patient, has addressed the former problem. More specific imaging guidelines are required for geriatric and pediatric patients.57
The development of a protocol for cervical spine clearance in the unconscious trauma patient has been more challenging, despite extensive research. At the center of this issue is the facilitation of nursing and medical care by having a patient’s cervical spine cleared versus the risk of a missed unstable injury, the sequelae of which may lead to SCI. Presently, flexion-extension views performed by experienced personnel can probably exclude instability in adults but do not exclude soft tissue, including disc, or SCIs.58 MRI provides the answers to these questions but presents numerous logistic problems.
Thin-section spiral CT, or now multi-slice CT, has justifiably become the first-line evaluation of the cervical and thoracolumbar spine in the poly-trauma patient.58–60 Not only is CT more diagnostically accurate than plain radiographs, but CT is quick and more cost effective.61 Essentially, technology and good science have made the lateral C-spine radiograph obsolete, and simplified the diagnostic challenges inherent in the anatomy of the occipito-cervical and cervical-thoracic junctions.
The importance of the clinical evaluation in addition to the aforementioned imaging methods are necessary for achieving the highest diagnostic accuracy. In the acute trauma phase, postponing treatment to obtain an imaging study may compromise outcome and expose the patient to further unnecessary stress. An excellent example is the patient with incomplete neurology secondary to a cervical unilateral or bilateral facet injury and the risk of a damaged disc causing further neurologic injury on reduction. Perhaps taking the patient to the operating room immediately and performing an anterior discectomy, reduction, and fusion is a better approach, given the established use of the procedure (Kwon et al, unpublished data, 2005) versus the delay and immobilization risks associated with performing MRI.
Great surgical advances have occurred over the last 15–20 years that have changed the way we treat spinal injuries. The ability to visualize cord and column pathology accurately has facilitated preoperative planning and ensured adequate decompression. Advancements in biomaterials and surgical techniques have made the restoration of the spinal column alignment relatively easy compared to the challenges faced by our predecessors. Probably the best examples are the anterior locking plate and posterior rod-screw systems that have revolutionized cervical fixation from the occiput to the upper thoracic spine and made the halo thoracic vest relatively obsolete.62 Surgical treatment of injuries to the previously daunting anatomy and biomechanics of the occipito-cervical junction has been facilitated by C1–C2 transarticular screws, C1 lateral mass screws, C2 pedicle screws, and various experimental anterior C1–C2 screw techniques.63,64 Odontoid screw fixation has gained widespread popularity, but its theoretical and perceived superiority over the gold standard halo must await the results of appropriately powered prospective randomized studies now in progress.
The evolution of minimally invasive surgery for cervical trauma will require the synergy of image guidance technology with percutaneous and endoscopic techniques currently being used in elective spinal surgery. Although minimally invasive surgery in cervical trauma is currently unrealistic, improvements in intraoperative CT and MRI will soon allow the spine surgeon to identify pathology and anatomic landmarks accurately, enabling the rapid realignment and/or decompression, precise localizing of instrumentation, and, thus, improved care with less local and systemic morbidity. The seemingly obvious and intuitive use of these techniques must not be allowed to overwhelm the fundamental anatomic, biomechanical, and clinical relationships and knowledge that are paramount to optimal surgical care.
In the thoracic spine, the growing use of pedicle screws has enabled surgeons to attain better alignment and more rigid fixation. The safety and accuracy of thoracic pedicle screws in trauma has been studied, and favorable results support their use by appropriately trained surgeons.65 Whether the use of screws is superior to hooks, or other conventional forms of fixation or treatment such as bed rest, is yet to be determined, but stiffer and more rigid constructs with fewer points of fixation should lead to shorter constructs sparing motion segments and more aggressive postoperative mobilization without orthoses. Reconstruction of the anterior and middle columns of the spine has been assisted by a spectrum of prosthetic devices, including fixed and expandable cages, allograft, and new anterior instrumentation systems, which can be placed with open or minimally invasive techniques, such as endoscopic surgery.66,67 Whether the advantages of endoscopic surgery can overcome the surgical learning curve and generalizability issues in thoracic and lumbar trauma, has yet to be determined.68
The treatment of thoracolumbar trauma continues to be one of the most controversial areas in all of spine trauma. Two well-designed systematic reviews, 1 addressing surgical technique69 and the second the operative versus nonoperative treatment of thoracolumbar burst fractures70 appear to summarize the current status best. Most of the evidence is based on retrospective case series and is insufficient to develop evidence-based guidelines for the treatment of these fractures. Higher levels of evidence do support the nonoperative treatment of so-called stable burst fractures based on conventional outcomes of HRQOL.71 With similar long-term HRQOL outcomes, regardless of treatment methods, future studies must consider outcomes more relevant to cost issues and early functional recovery. Numerous classifications have contributed to improved treatment of these injuries, but none have delivered all the essential components of a classification system. Work by Vaccaro et al72 toward a reliable, valid, and all encompassing classification is eagerly anticipated.
The introduction of vertebroplasty and kyphoplasty to the treatment of thoracolumbar fractures has added new controversy, particularly regarding the indications and long-term outcomes. Demographic patterns over the next half century suggest staggering financial implications.73 Several prospective studies support both techniques’ efficacy in pain relief and kyphoplasty’s role in partially restoring sagittal balance. An appropriate emphasis on prevention of osteoporosis may curb the demand for these procedures.
Another area of spine trauma brimming in controversy relates to the timing of surgical intervention. Although basic science studies support the early decompression of compromised neurologic tissues, similar studies in human beings have not been feasible. A metaanalysis studying the effect of early decompression on neurology identified the complexities involved in analyzing the literature and properly studying the problem.74 The overwhelming logistics around a prospective study to answer this question have been taken on by M. Fehlings, A. Vaccaro, and the Spine Trauma Study Group in a large observational study “STASCIS.” The results of this study will likely have significant implications on the way spine surgeons treat the patient with SCI. In neurologically intact patients, the evidence is becoming clearer that early surgical stabilization is probably indicated (within 3 days of injury) to decrease hospital stay, incidence of pneumonia, ventilator days, and hospital charges.75
Although becoming relatively commonplace in elective spine surgery, biologics have not been a major consideration in spine trauma surgery. Still, there may be a role for growth factors and/or other osteoconductive bone substitutes, especially as minimally invasive surgery gains momentum in spine trauma.76–78 The use of bioabsorbable implants in spine trauma is based on overcoming the limitations of current instrumentation, namely, image degradation, stress shielding, and implant loosening.79 Although the use of these polymers is still at the preclinical or early clinical phase, they hold promise not only for fixation and containment but for the delivery of growth factors and antibiotics.
Unequivocally, the most exciting area in biologics is the work being performed in SCI, in which scientific discovery over the past 3 decades has generated promise for patients, scientists, and clinicians that paralysis will someday be cured. Animal research has generated promising experimental therapies but has also revealed a daunting complexity of the neurobiologic challenges that impede neural repair after injury.80 Understanding these factors will be key for the further development of therapeutic strategies. There have been many encouraging reports of promoting axonal regeneration and novel neuroprotective agents, such as minocycline and erythropoietin, which serve as the foundation for cautious optimism that truly effective therapies for SCI will emerge in our generation. The initiation of human trials for experimental therapies represents the forward movement of this knowledge but also speaks loudly for epidemiologically sound and rigorous clinical evaluation. As the list of therapies available for human testing grows, equipoise will be necessary in this field of “spinal cord regeneration,” which has traditionally been viewed as the realm of laboratory researchers but now demands leadership from clinicians with interest and expertise in clinical research methodology.
Demands from payers who want a better appreciation of what is the best evidence have encouraged the practice of evidence-based medicine. Sackett et al81 define evidence-based medicine as the “conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.” However, it is noteworthy that evidence-based medicine incorporates clinical expertise and experience, along with patient characteristics and wishes. Furthermore, evidence-based medicine does not have to be derived from randomized trials or metaanalysis, it could be based on any or all study designs, depending on the question being asked. Objective measures such as mortality rates are now being replaced by patient-focused outcomes, which assess attributes like HRQOL in many areas of clinical practice. Inclusion of instruments such as the Short Form-36 (SF-36) has advanced our understanding of the sequelae following spinal trauma by allowing comparison of physical and mental functioning with normative data for the general population and other disease conditions.82,83
A major limitation of early studies investigating HRQOL following injury was the lack of baseline measures that could be used in gauging the change in health status since the time of injury. Normative data for the SF-36 are valuable because they can provide an estimate of the pre-injury status, and consider differences in age and gender. Another innovative approach is the idea of asking spine trauma patients to recall their pre-injury HRQOL, thinking back to the time just before their injury. A study by Thomas et al84 showed that further research assessing the validity of using recalled baseline values is warranted because it can provide individual level data regarding pre-injury health status.
In the future, measures in spinal trauma will likely be developed using innovative psychometric methods such as item response theory, which offer advantages like improved measurement precision and the ability to conduct dynamic assessments using computerized adaptive testing.85 There will also be a trend toward using conceptual models such as the International Classification of Functioning, Disability and Health,86 developed by the World Health Organization to understand the behavioral and social impacts that result from health conditions, like spine trauma. The International Classification of Functioning, Disability and Health, a revised version of the International Classification of Impairments, Disabilities and Handicaps, views the health condition from the body, individual, and societal perspective. It also relates personal factors and the environment (physical, social, and attitudes) to the health condition, providing a more comprehensive and meaningful picture. This type of model will foster new ideas in clinical care and research in all phases of the continuum, including acute care, rehabilitation, community living, and health service planning.
Increasing costs will also make health economic evaluation more prominent in the literature. The unsustainable economics of ever-increasing technology and patient expectations will make economic evaluation critical in assisting health planners to evaluate interventions using “cost-benefit” frameworks.87 The use of preference-based measures such as the EQ-5D88 and the Health Utilities Index89 will be incorporated into clinical trials to allow for cost utility analysis. There will also be a trend toward applying economic methods to health measures such as the SF-36, producing new preference-based measures, like the SF-6D.90 This process has the advantage of being able to obtain quality adjusted life years from existing or prospective SF-36 data.90
The epidemiology, process, and outcome of spine trauma are in a dynamic phase of growth and reevaluation. With the technology readily available, not only from a treatment but data collection perspective, providers must be cognizant of ungoverned therapeutic behavior, and supportive of careful research and quality assurance planning to ensure affordability and optimal patient outcomes.
- Scientific and fiscal accountability are taking on a more prominent role in defining diagnostic and therapeutic interventions in spine trauma patients.
- Demographic and societal trends are creating unique spine trauma challenges in the elderly population.
- Multicenter studies lead by spine trauma focus groups will hopefully provide high levels of evidence in answering both old and new questions in spine trauma.
The authors thank Juliet Batke, from the Vancouver Spine Research Centre, for all her assistance in helping prepare this manuscript.
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