Odontoid fractures account for between 10% and 20% of all cervical spine fractures with a well-described bimodal age distribution of patients with a smaller peak occurring in younger, physically active, and healthy commonly male patients and a second increasingly larger peak of elderly and medically infirm patients with a larger number of female patients (1,2). Many of the fractures in the elderly are the result of low-energy mechanisms such as groundlevel falls, while odontoid fractures in younger adults occur during high-energy deceleration trauma such as motor vehicle collisions. A less common but nonetheless important injury cohort is seen in children under the age of 7 with disruption of the not-yet ossified synchondrosis of the dens.

The main inherent challenges associated with odontoid fractures emerge out of the surrounding circumstances of odontoid fractures: The younger odontoid injury population injured in high-velocity injuries are commonly polytraumatized, with concurrent head injuries, complex associated cervical spine trauma creating variable circumstances (3). The elderly population group is frequently adversely affected by comorbidities, such as dementia, ankylosing spinal disorders, osteopenia, and therapeutic anticoagulant use, to name but a few. Both sets of circumstances test clinicians in their own ways. For instance, both groups of patient share similar concerns of missed injuries
and delay in diagnosis. For multiply injured patients, this can result out of the turmoil of acute polytrauma care, while lack of initial focal patient complaints, dementia, osteopenia, and arthritic changes in elderly patients may explain delay in diagnosis in that age cohort. Fortunately, it appears that spinal cord injury—either of primary or of secondary nature—is relatively rare, perhaps a benefit of the relatively capacious spinal canal found between the foramen magnum and the C2-C3 disk space (4,5). While spinal cord injuries as a result of an odontoid injury are fortunately rare in this fracture cohort, they may be devastating and are probably underreported as an entity due to their associated circumstances—such as respiratory arrest at the time of injury. In patients who survived their injuries, the neurologic involvement reported is under 25% with a spectrum of injuries seen, such as Brown-Sequard Syndrome, mild upper extremity weakness, lower extremity hyperreflexia, as well as greater occipital neuralgia (5, 6 and 7).
With encouraging signs of decreasing numbers of odontoid fractures in the younger patient population perhaps reflecting benefits of greater vehicular safety measures, the clearly emerging clinical concern centers on the increasingly larger segment of elderly patient with odontoid fractures. These injuries occur in two subsets of the elderly: The one subset is highly active despite being affected by some age typical comorbidities. Injuries in this segment occur from car crashes, falls from heights during recreational activities, and work. Pharmaceutically induced anticoagulation, ankylosing spinal columns, pervasive cervical spondylosis, and obesity are some of the more commonly encountered comorbidities of these patients. The other patient cohort usually is injured in a highly consistent fashion—from a simple ground-level fall—yet poses a major threat to patient survival due to the circumstances leading up to the fall. Dementia, diminished neurocognitive skills, and major comorbidities can accumulate to substantial ethical and social challenges for all involved in the care process. These circumstances are not dissimilar to those encountered in other geriatric fractures such as in the hip, the proximal humerus, the distal radius, and others. Most of these “insufficiency fractures” are associated with falls from a standing height and can be linked to advanced pulmonary and cardiovascular disease, peripheral neuropathy, poor posture, weak muscle tone, joint contractures, insufficient proprioception, and generalized deconditioning in the setting of senile osteoporosis or -malacia. Because of the rapidly growing “geriatric” demographic population segment, improved sensible odontoid fracture care algorithms for the elderly are of significant importance from a societal and economic perspective (8).

In the discussions of odontoid fractures the adult and geriatric perspectives frequently overshadow the pediatric domain. Cervical spine injuries, although rare in skeletally immature children, especially the very young, predominantly occur at the craniocervical junction (Oc-C2), with the majority of fractures being odontoid injuries. The disproportionately larger size and weight of the skull relative to the neck and trunk of a pediatric patient creates a mechanical disadvantage within the upper half of the cervical spine. Upper cervical spine injuries predominate in the pediatric population with the odontoid representing the majority of these injuries (9,10). The last synchondrosis of the axis to ossify is the subdental synchondrosis at the junction of the odontoid process and the body. This process is usually complete by 7 years of age (11). As a result of this developmental process, most pediatric dens fractures occur through this growth plate and are most frequently seen before the age of 7 and often associated with a hyperflexion mechanism (12).

Attempts at identifying general treatment algorithms for all types of odontoid fractures are bound to fail in light of the disparate epidemiology of patients affected and their divergent age-related associated medical burden. Current clinical research has increasingly focused on geriatric odontoid fractures due to starkly rising numbers of these injuries compared to declining fracture numbers in patients below 65 years of age and unresolved care issues in light of 1-year mortality rates regardless of treatment of over 40% (8). Several recent studies are focused on establishing a better understanding of the osteoporotic host and creating evidence-based guidelines for treatment.

The circumstances surrounding the occurrence of odontoid fractures can make physical examination less than straightforward. In patients with high-impact injury, the serious nature of associated injuries can make the clinical diagnosis difficult. In the elderly patient group, dementia and senility can make communication about pain difficult. In cognitively unimpaired patients, upper cervical spine fractures are usually accompanied by complaints of neck pain, headache, and nuchal tenderness. There may be some swelling and ecchymosis over the fracture site in the back of the neck, but this is not a common finding on physical exam. Palpation may reveal crepitus, but there is a paucity of objective physical examination findings. A full neurologic assessment is obtained, and the subaxial, thoracic, and lumbar spine should be evaluated for any local tenderness or step deformity to rule out any noncontiguous spine fractures. Dysphagia, with associated increased risk of aspiration, may be present from an expected retropharyngeal hematoma and may be more commonly

encountered in patients with advanced age (20). Should a patient be neurocognitively intact and if medically not contrain dicated, a simple swallowing test such as performed in an upright position with a small amount of water ingested from ice chips may help determine presence of traumatically related dysphagia—an important component in the decision-making process for definitive care.

Neurologic assessment is preferably performed according to American Spinal Injury Association guidelines (21). In the rare cases of primary spinal cord injury associated with odontoid fractures, asymmetric patterns of upper and/or lower extremity weakness and numbness may be present. Cranial nerve function should be part of any examination of patients with possible head or neck injuries. The abducens and hypoglossal nerves are most commonly affected by craniocervical injuries (22). A wide variety of neurologic injury patterns are possible in patients with trauma to the upper cervical spine. These range from complete pentaplegia with loss of respiratory function to incomplete injuries, such as cervicomedullary syndromes and disorders affecting brainstem function. The cervicomedullary syndromes, which include cruciate paralysis, as described by Bell, and hemiplegia cruciata initially described by Wallenberg, represent the more unusual forms of incomplete spinal cord injury and are a result of the specific anatomy of the spinal tracts at the junction of the brainstem and spinal cord (22). Cruciate paralysis can be similar to a central cord syndrome, although it normally affects proximal more than distal upper extremity function. Hemiplegia cruciata is associated with ipsilateral arm and contralateral leg weakness. Due to the rostral nature of a potentially accompanying spinal cord injury, breathing, swallowing, and gag reflex may be impaired to a variable degree (22). In extreme cases, complete quadriplegia may result from an odontoid fracture. Due to the expected respiratory arrest of an injury at such a level, survival is rare and strongly correlated to timing of airway restoration.

In a geriatric patient with decreased general functional status, the primary focus of assessment is targeted on identifying the odontoid injury in the first place and then looking for typical associated injuries, such as hip and wrist fractures. In geriatric patients with diminished functional baseline status, it is quite common to receive nothing more than vague and nonspecific complaints of neck ache and some occipital pain. It is very helpful in the treatment decision-making process to elicit reliable and meaningful reports of the patient’s preoperative functional status from spouses, family, or care providers and identify associated clinical comorbidities that may affect the management plan (23).