The axial load teardrop fracture. A biomechanical, clinical and roentgenographic analysis

Imaging of Hockey-related Injuries of the Head, Neck, and Body

Hockey is a demanding contact sport with growing popularity around the world. This article is part of a review series in this issue of Seminars in Musculoskeletal Radiology that summarizes epidemiological research on the patterns of ice hockey injuries as well as provides pictorial examples for a radiologist's perspective. We focus on non-extremity pathologies which encompass many of the most devastating injuries of hockey, namely those involving the head, neck, face, spine, and body.

Cervical Spine Injuries in the Ice Hockey Player: Current Concepts in Epidemiology, Management and Prevention

STUDY DESIGN

This review article examines the biomechanics that underly hockey-related cervical spine injuries, the preventative measures to curtail them, optimal management strategies for the injured player and return to play criteria.

OBJECTIVE

Hockey is a sport with one of the highest rates of cervical spine injury, but by understanding the underlying pathophysiology and context in which these injuries can occur, it is possible to reduce their incidence and successfully manage the injured player.

METHODS

Multiple online databases including PubMed, Google Scholar, Columbia Libraries Catalog, Cochrane Library and Ovid MEDLINE were queried for original articles concerning spinal injuries in ice hockey. All relevant papers were screened and subsequently organized for discussion in our subtopics.

RESULTS

Cervical fractures in ice hockey most often occur due to an increased axial load, with a check from behind the most common precipitating event.

CONCLUSIONS

Despite the recognized risk for cervical spine trauma in ice hockey, further research is still needed to optimize protocols for both mitigating injury risk and managing injured players.

Reduction and Open Fixation of a Cervical Teardrop Fracture: A Technical Note

BACKGROUND

Cervical teardrop fractures are hyperflexion and axial loading injuries associated with significant ligamentous disruption. Patients sustaining these types of injury are classically treated with a cervical corpectomy and anterior fusion. However, there are notable disadvantages of this approach, namely, disruption of the patient's true anatomic alignment and a reduction in the number of fixation points available for cervical fusion. Here we present a novel method of open reduction and internal fixation in a neurologically intact patient with cervical teardrop fracture.

CASE DESCRIPTION

A 34-year-old man presented to Ryder Trauma Center after a helmeted motorcycle accident. The patient was found to be neurologically intact on arrival, and imaging demonstrated a C5 teardrop fracture without bony retropulsion. The patient was taken to the operating room for an open reduction and internal fixation of the fracture using a novel technique. This technique used traditional diskectomies at the C4-5 and C5-6 levels, along with a temporary, unicortical screw into the C5 body to capture the anteriorly displaced fragment. A bicortical screw was then placed into the contralateral side, and now, having fully reduced the fracture, the first (temporary) screw was replaced with a bicortical screw. The patient was neurologically intact postoperatively, with 2-month follow-up computed tomography scan demonstrating stable reduction of the fracture.

CONCLUSIONS

Here we present a novel technique for open reduction and internal fixation of a cervical teardrop fracture that does not require cervical corpectomy. This technique is particularly useful in patients with an anteriorly displaced fragment and without neurologic deficit or compromise.

The effect of single-handed lifting tasks on the activation of the neck-shoulder shared musculature

The use of the hand in lifting has been linked to occupational injuries of the neck and shoulder. This research is aimed at examining the effect of work-related factors on the major neck-shoulder shared musculature activity on both sides of the cervical spine for a right-handed lifting task. Subjects lifted different weights from 20 different locations produced by the interaction of varying heights, reach distance, and angles simulating the work done by assembly line workers. All lifting tasks were done by the right hand. Bilateral electromyography data of major shared musculature (upper trapezius, sternocleidomastoid, and levator scapula) were collected using surface EMG electrodes. Analyses demonstrate that work-related factors; hand weights, reach distance, angles, and gender significantly affect the activation level of active shared musculature of the neck. Results also showed that the active shared musculature (the right side) has a significant influence on the activation of the antagonistic shared musculature. The findings show that reducing the weights being handled and keeping work area closer to the body reduces the muscle activities in the shared muscles. These findings may be used to build a biomechanical model to predict the compressive forces acting on the cervical spine due to one hand lifting.

Management of Sub-axial Cervical Spine Injuries

Sub-axial cervical spine injuries are commonly seen in patients with blunt trauma. They may be associated with spinal cord injury resulting in tetraplegia and severe permanent disability. Immobilization of the neck, maintenance of blood pressure and oxygenation, rapid clinical and radiological assessment of all injuries, and realignment of the spinal column are the key steps in the emergency management of these injuries. The role of intravenous methylprednisolone administration in acute spinal cord injuries remains controversial. The definitive management of these injuries is based upon recognition of the fracture pattern, assessment of the degree of instability, the presence or absence of neurologic deficit, and other patient related factors that may influence the outcome. Nonoperative treatment comprises of some form of external immobilization for 8 to 12 weeks, followed by imaging to assess fracture healing, and to rule out instability. The goals of surgery are realignment of the vertebral column, decompression of the neural elements and instrumented stabilization.

Cervical Spine Injuries in the Athlete

Cervical spine injuries are extremely common and range from relatively minor injuries, such as cervical muscle strains, to severe, life-threatening cervical fractures with spinal cord injuries. Although cervical spine injuries are most common in athletes who participate in contact and collision sports, such as American football and rugby, they also have been reported in athletes who participate in noncontact sports, such as baseball, gymnastics, and diving. Cervical spine injuries in athletes are not necessarily the result of substantial spine trauma; some athletes have chronic conditions, such as congenital stenosis, that increase their risk for a serious cervical spine injury after even minor trauma. Therefore, physicians who cover athletic events must have a thorough knowledge of cervical spine injures and the most appropriate ways in which they should be managed. Although cervical spine injuries can be career-ending injuries, athletes often are able to return to play after appropriate treatment if the potential for substantial re-injury is minimized.

Teardrop fracture following head-first impact in an ice hockey player: Case report and analysis of injury mechanisms

BACKGROUND

We report a case of a young male athlete who sustained a three column displaced teardrop fracture of the C5 vertebra due to a head-first impact in hockey, suffered neurapraxia, yet made full neurological recovery. This full recovery was in sharp contrast to multiple case series which reported permanent quadriplegia in the vast majority of teardrop fracture patients. We investigate the etiology and biomechanical mechanisms of injury.

METHODS

Admission imaging revealed the teardrop fracture which consisted of: a frontal plane fracture which separated an anterior quadrilateral-shaped fragment from the posterior vertebral body; a vertical fracture of the posterior vertebral body in the sagittal plane; and incomplete fractures of the neural arch that initiated superiorly at the anterior aspect of the spinous process and left lamina adjacent to the superior facet. Epidural hematoma in the region of the C5 vertebra was observed in addition to disc and ligamentous disruptions at C4-5 and C5-6. Our patient was ultimately treated surgically with anterior fusion from C4 through C6 and subsequently with bilateral posterior fusion at C5-6.

RESULTS

The injuries were caused by high-energy axial compression with the neck in a pre-flexed posture. The first fracture event consisted of the anterior vertebral body fragment being sheared off of the posterior fragment under the compression load due in part to the sagittal plane concavity of the C5 inferior endplate. The etiology of the vertical fracture of the posterior vertebral body fragment in the sagittal plane was consistent with a previously described hypothesis of the mechanistic injury events. First, the C4-5 disc height decreased under load which increased its hoop stress. Next, this increased hoop stress transferred lateral forces to the C5 uncinate processes which caused their outward expansion. Finally, the outward expansion of the uncinate processes caused the left and right sides of the vertebral body to split and spread. Evidence in support of this mechanistic event sequence was provided by the neural arch fractures which initiated superiorly, average angulation of the C5 uncinate processes, and similar well-established mechanisms causing vertical fractures at other spinal regions.

CONCLUSIONS

Our case study and analyses provide insight into the etiology of the specific teardrop fracture patterns observed clinically.

An investigation into axial impacts of the cervical spine using digital image correlation

BACKGROUND CONTEXT

High-energy impacts are commonly encountered during sports such as rugby union. Although catastrophic injuries resulting from such impacts are rare, the consequences can be devastating for all those involved. A greater level of understanding of cervical spine injury mechanisms is required, with the ultimate aim of minimizing such injuries.

PURPOSE

The present study aimed to provide a greater understanding of cervical spine injury mechanisms, by subjecting porcine spinal specimens to impact conditions based on those measured in vivo. The impacts were investigated using high-speed digital image correlation (DIC), a method not previously adopted for spinal impact research.

STUDY DESIGN

This was an in vitro biomechanical study.

METHODS

Eight porcine specimens were impacted using a custom-made rig. The cranial and caudal axial loads were measured at 1 MHz. Video data were captured with two cameras at 4 kHz, providing measurements of the three-dimensional deformation and surface strain field of the specimens using DIC.

RESULTS

The injuries induced on the specimens were similar to those observed clinically. The mean±standard deviation peak caudal load was 6.0±2.1 kN, which occurred 5.6±1.1 ms after impact. Damage observable with the video data occurred in six specimens, 5.4±1.1 ms after impact, and the peak surface strain at fracture initiation was 4.6±0.5%.

CONCLUSIONS

This study has provided an unprecedented insight into the injury mechanisms of the cervical spine during impact loading. The posture represents a key factor in injury initiation, with lordosis of the spine increasing the likelihood of injury.

Tear-drop fracture of the axis in a child with an 8-year follow-up: a case report

We reported a 12-year-old boy with neck pain and dysphagia 6 days after his neck being tied by another boy's arms from the back. The boy was found to have a tear-drop fracture of the axis in both radiograph and MRI, which was a rare case in children. He was placed in a cervical traction with Glisson belt and received transfusion for 2 weeks until his neck pain and dysphagia were released. Thereafter, an operation of anterior fusion and fixation was chosen to ensure further stability of the cervical spine and replacement of the fracture fragment. An 8-year follow-up examination showed a satisfactory range of motion of the cervical spine, fusion at C2-3 intervertebral space, and normal signal of C3-4 intervertebral disk. We conclude that tear-drop fractures of the axis in children may be caused by extension injury without a high-energy trauma, and operation of anterior fusion and fixation can be the treatment of choice.

Injury and biomechanical perspectives on the rugby scrum: a review of the literature

As a collision sport, rugby union has a relatively high overall injury incidence, with most injuries being associated with contact events. Historically, the set scrum has been a focus of the sports medicine community due to the perceived risk of catastrophic spinal injury during scrummaging. The contemporary rugby union scrum is a highly dynamic activity but to this point has not been well characterised mechanically. In this review, we synthesise the available research literature relating to the medical and biomechanical aspects of the rugby union scrum, in order to (1) review the injury epidemiology of rugby scrummaging; (2) consider the evidence for specific injury mechanisms existing to cause serious scrum injuries and (3) synthesise the information available on the biomechanics of scrummaging, primarily with respect to force production. The review highlights that the incidence of acute injury associated with scrummaging is moderate but the risk per event is high. The review also suggests an emerging acknowledgement of the potential for scrummaging to lead to premature chronic degeneration injuries of the cervical spine and summarises the mechanisms by which these chronic injuries are thought to occur. More recent biomechanical studies of rugby scrummaging confirm that scrum engagement forces are high and multiplanar, but can be altered through modifications to the scrum engagement process which control the engagement velocity. As the set scrum is a relatively 'controlled' contact situation within rugby union, it remains an important area for intervention with a long-term goal of injury reduction.

MDCT and MRI evaluation of cervical spine trauma

Purpose

Cervical spine injuries following major trauma result in significant associated morbidity and mortality. Devastating neurological injury, including complete and incomplete tetraplegia, are common sequelae of cervical spine trauma and cause profound and life-altering medical, financial, and social consequences. Most cervical spine injuries follow motor vehicle accidents, falls, and violence. The proliferation of multidetector computed tomography allows for fast and accurate screening for potential bony and vascular injuries. Magnetic resonance imaging is useful for evaluation of the supporting ligaments and the spinal cord after the patient has been stabilised.

Conclusion

Cervical spine injuries are approached with much caution by emergency room clinicians. Thus, it is essential that radiologists be able to differentiate between a stable and unstable injury on MDCT, as this information ultimately helps determine the management of such injuries.

Teaching Points:

MDCT and MRI are complementary and both may be needed to define injuries and determine management.

MDCT rapidly evaluates the bones, and MRI is superior for detecting ligament and cord injuries.

Injury to one of the three spinal columns may be stable, and injuries to more than one are unstable.

Instability may cause abnormal interspinous and interpedicular distances, or cervical malalignment.

Fractures of the foramen transversarium are associated with vertebral arterial dissection.

Advances in the management of spinal cord and spinal column injuries

Spinal cord injury (SCI) is a significant public problem, with recent data suggesting that over 1 million people in the U.S.A. alone are affected by paralysis resulting from SCI. Recent advances in prehospital care have improved survival as well as reduced incidence and severity of SCI following spine trauma. Furthermore, increased understanding of the secondary mechanisms of injury following SCI has provided improvements in critical care and acute management in patients suffering from SCI, thus limiting morbidity following injury. In addition, improved technology and biomechanical understanding of the mechanisms of spine trauma have allowed further advances in available techniques for spinal decompression and stabilization. In this chapter we review the most recent data and salient literature regarding SCI and address current controversies, including the use of pharmacological adjuncts in the setting of acute SCI. We will also attempt to provide a reader with basic understanding of the classifications of SCI and spinal column injury. Finally, we review advances in spinal column stabilization including improvements in instrumented fusion and minimally invasive surgery.

Fracture and contralateral dislocation of the twin facet joints of the lower cervical spine

PURPOSE

The combination of a facet fracture and a contralateral facet dislocation at the same intervertebral level of the cervical spine (a fracture and contralateral dislocation of the twin facet joints) has not been described in detail. The aims of this study are to report a series of 11 patients with this injury, to clarify the clinical features and to discuss its pathomechanism.

METHODS

Among 251 patients with lower cervical spine fractures and/or dislocations surgically treated, 11 (9 males and 2 females, averaged age, 52 years) had this kind of injury. Medical charts and medical images were reviewed retrospectively.

RESULTS

Injury levels were C4-5, C5-6 and C6-7 in 1, 4 and 6 patients, respectively. A fracture was found at the superior facet in 6, and at the inferior facet in 5. The anterior displacement of the vertebral body ranged from 7 to 19 mm. The unilateral horizontal facet appearance on an anteroposterior radiograph and the triple image on a CT composed of a separated fracture fragment, the base of the fractured facet, and the neighboring non-fractured facet were characteristic. All patients had neurological deficits from Frankel A to D, and were surgically treated by posterior fusion using wire or cable, or combined anterior and posterior spinal fusion.

CONCLUSIONS

The fracture and contralateral dislocation of the twin facet joints can cause severe neurological deficits because of its gross anterior displacement. Its plausible pathomechanism is extension force exerted to the cervical spine when it is maximally bent laterally.

The development and evaluation of the subaxial injury classification scoring system for cervical spine trauma

BACKGROUND

Fractures and dislocations of the subaxial cervical spine may give rise to devastating consequences. Previous algorithms for describing cervical trauma largely depend on retrospective reconstructions of injury mechanism and utilize nonspecific terminology which thus diminish their clinical relevance add to the difficulty of educating doctors and performing prospective research.

QUESTIONS/PURPOSES

We characterized the potential benefits of the Subaxial Injury Classification (SLIC) scale which considers three major variables that influence spinal stability: morphology, integrity of the discoligamentous complex, and neurologic status. Each category was assigned a certain number of points based on the severity of the injury which are added together to generate a total score; this value provides prognostic information and may also be useful for directing subsequent management (ie, nonoperative treatment versus operative intervention).

METHODS

We examined the individual components that comprise the SLIC paradigm and reviewed the manner in which cervical injuries are scored and stratified. We also critically assessed the preliminary data comparing the SLIC scheme to preexisting classification systems.

RESULTS

The results of a preliminary analysis demonstrate that the intraclass coefficients (ICC) for the three primary components range between 0.49 and 0.90, suggesting that the overall reliability of the SLIC system appears to be at least as good as that of other conventional schemes for classifying subaxial cervical spine trauma (ICC between 0.41 and 0.53).

CONCLUSIONS

This scheme will hopefully facilitate the development of evidence-based guidelines that may influence other aspects of the therapeutic decision-making process (eg, which operative approach is most appropriate for a particular injury). We anticipate its accuracy and reproducibility will increase over time as surgeons become more familiar with the protocol.

Spine trauma

Spinal fractures represent 3% to 6% of all skeletal injuries. Spine trauma is a complex diagnostic area in which the radiological assessment is crucial. Plain radiography is often used as the initial diagnostic modality. However, stabilization of the acutely injured spine is a primary concern. In this respect, computed tomography (CT) is vastly superior to plain film in terms of speed and accuracy. In many trauma centers, CT has replaced plain film as the primary modality for evaluation of spinal trauma. Magnetic resonance imaging is not indicated for all cases of spinal trauma but provides detailed information about soft tissue structures including the intervertebral disc, the ligaments, the epidural space, the blood vessels, and the spinal cord. MR imaging provides information on these structures not obtained from other modalities. Patients with spinal cord injury may suffer devastating long-term neurologic deficits, so prompt and efficient spinal imaging guidelines are necessary in all trauma centers.

Sideline and ringside evaluation for brain and spinal injuries

✓Participation in contact and collision sports carries an inherent risk of injury to the athlete, with damage to the nervous system producing the most potential for significant morbidity and death. Neurological injuries suffered during athletic competition must be treated promptly and correctly to optimize outcome, and differentiation between minor and serious damage is the foundation of sideline/ringside management of the injury. In this article the authors present a guide to the sideline or ringside identification and management of head and spinal injuries.

Central nervous system injuries in sport and recreation: a systematic review

Many sports have been associated with a variety of neurological injuries affecting the central nervous system (CNS), with some injuries specific to that sport. A systematic review of sport-specific CNS injuries has not been attempted previously, and could assist in the understanding of morbidity and mortality associated with particular sporting activities, either professional or amateur. A systematic review of the literature was performed using PubMed (1965-2003) examining all known sports and a range of possible CNS injuries attributable to that sport. Numerous sporting activities (45) have associated CNS injuries as reported within the literature. The sports most commonly associated with CNS injuries are: football, boxing, hockey, use of a trampoline, and various winter activities. A number of sporting activities are associated with unique CNS injuries or injury-related diseases such as heat stroke in auto racing, vertebral artery dissection in the martial arts, and dementia pugilistica in boxing. Neurological injuries of the CNS due to sport comprise a wide collection of maladies that are important for the neurologist, neurosurgeon, orthopaedic surgeon, physiatrist, sports medicine doctor, athletic trainer and general physician to recognise.

Catastrophic cervical spine injuries in the collision sport athlete, part 1: epidemiology, functional anatomy, and diagnosis

Catastrophic cervical spine injuries can lead to devastating consequences for the collision athlete. Improved understanding of these injuries can facilitate early diagnosis and effective on-field management. This article is the first of a 2-part series. The first part reviews the current concepts regarding the epidemiology, functional anatomy, and diagnostic considerations relevant to cervical spine trauma in collision sports. In the second part, to be published later, the principles of emergency care of the cervical spine-injured athlete are reviewed. This article provides a rational approach to the early recognition of the different clinical syndromes associated with catastrophic cervical spine injury. Rapid on-field diagnosis can help to optimize the outcomes of these catastrophic injuries.

Fracture « tear-drop » en extension de l’axis

Tear-drop fracture of the axis is an exceptional spinal fracture which generally occurs after high-energy trauma with hyper-extension of the cervical spine. Purely anterior fracture can occur with no real impact on stability. Orthopedic treatment provides good results in this situation. If the fracture is posterior, it continues into the C2-C3 intervertebral disc and the common posterior vertebral ligament, leading to C2C3 instability and possible retrolisthesis of C2 over C3 and neurological involvement. We report a case of tear-drop fracture of C2 with C3 instability without neurological involvement. This patient underwent posterior fixation with C2C3 arthrodesis which provided good quality bone fusion without secondary displacement or clinical aggravation.

Morphometry of the spinal canal at cervical region in asymptomatic military young men

Spinal canal measurements obtainned from radiographic imaging studies are an integral part of diagnostic evaluation of cervical spine stenosis. Before abnormal spinal morphometry can be determined, it is first necessary to establish normal values for the specific patient population being evaluated. Cervical spinal canal stenosis increase risk of quadriplegia after "minor trauma" in the head or neck, mainly in athletes who participate in contact or collision sports. Prospective and random selection of 500 plain film of the lateral cervical spine in young militaries population in age group 18-20 years old. Those were performed a hundred set of film were for each geographic region, including Manaus, Recife, São Paulo, Porto Alegre and Campo Grande. The first part of this study established normal values for cervical morphometry. The second part determined the most accurate screenning method for detecting cervical spinal stenosis. Normal spinal canal mean value for C3 was 18,27mm, C4 17,98mm, C5 18,33mm and 18,76mm in C6. The TORG ratio was evaluated as a method to detect significant cervical spinal stenosis and was shown to have sensitivity and high positive predictive value. It was observed TORG's ratio of 0,80 or less in 14,4% of the X-rays.

In neck to neck competition are women more fragile?

Recent studies indicate numerous differences between female and male athletes regarding injuries of the upper and lower extremities. Studies have been much less clear concerning a gender differential regarding injuries of the cervical spine. For the purposes of the current review, injuries have been divided into three categories. The first category is cervical strain injury. It has been reported that strain injuries are more prevalent in female athletes than male athletes. The second category is cervical disc injury and cervical disc herniation. It has been reported that the male to female incidence is approximately equal in this category. In the third category, which is referred to as major structural injury, studies to date have almost entirely reported on injuries in males showing a significant male preponderance. With increasing participation of women in contact sports that cause major structural injury, a greater incidence of these injuries may be seen in women.

The effects of padded surfaces on the risk for cervical spine injury

STUDY DESIGN

This is an in vitro study comparing cervical spine injuries produced in rigid head impacts and in padded head impacts.

OBJECTIVES

To test the hypothesis that deformable impact surfaces pose a greater risk for cervical spine injury than rigid surfaces using a cadaver-based model that includes the effects of the head and torso masses.

SUMMARY OF BACKGROUND DATA

It is widely assumed that energy-absorbing devices that protect the head from injury also reduce the risk for neck injury. However, this has not been demonstrated in any experimental or epidemiologic study. On the contrary, some studies have shown that padded surfaces have no effect on neck injury risk, and others have suggested that they can increase risk.

METHODS

Experiments were performed on 18 cadaveric cervical spines to test 6 combinations of impact angle and impact surface padding. The impact surface was oriented at -15 degrees (posterior impact), 0 degree (vertex impact), or +15 degrees (anterior impact). The impact surface was either a 3-mm sheet of lubricated Teflon or 5 cm of polyurethane foam.

RESULTS

Impacts onto padded surfaces produced significantly larger neck impulses (P = 0.00023) and a significantly greater frequency of cervical spine injuries than rigid impacts (P = 0.0375). The impact angle was also correlated with injury risk (P < 0.00001).

CONCLUSIONS

These experiments suggest that highly deformable, padded contact surfaces should be used carefully in environments where there is the risk for cervical spine injury. The results also suggest that the orientation of the head, neck, and torso relative to the impact surface is of equal if not greater importance in neck injury risk.

Differences in mechanical response between fractured and non-fractured spines under high-speed impact

OBJECTIVE: The differences in mechanical response between fractured and non-fractured spines were investigated using a porcine spine impact model. DESIGN: Ten three-vertebrae segments (C3-C5) of porcine spine were subjected to a single impact to study the trauma mechanism. Small steel balls glued to the vertebra and a high-speed camera were used to observe the deformation of vertebral body and disc during impact. After trauma, the episodes of fractured specimens were compared with those of non-fractured specimens. BACKGROUND: Experimental trauma models using the spines of mature animals have rarely been evaluated. Finding a well-controlled, reproducible protocol based on an easily accessible specimen was therefore important. These models will be promising if clinical fractures can be produced. METHODS: All of the specimens were subjected to high-speed flexion-compression loading. The impact to the load cell and the operation of the high-speed camera were synchronized. The force-time sequence and disc deformation curve were recorded. The results from fractured and non-fractured spines were then compared. RESULTS: There were three burst fractures, four pedicle fractures, one facet joint fracture, one compression fracture and one fracture-dislocation. All of these fractures were similar to clinical fractures. Compared to non-fractured specimens, the fractured specimens had lower maximal force and longer reaction time. The characteristic steep decline in the middle region of the force-time curve was also consistently noted in the fractured spines. CONCLUSIONS: Spinal fractures similar to those found clinically were successfully produced in porcine spines. The characteristics of the mechanical responses observed should be helpful in the interpretation of events which occur during impact.

The preparticipation sports examination for high school and college athletes

The PSE can be used as a tool to allow athletes to participate safely in sports. The goal of the PSE is not to disqualify athletes but to ensure that their participation in sports does not unnecessarily increase their risk of injury. The PSE is most effectively conducted by the station method with multiple examiners, one of whom should have specialty training in musculoskeletal disorders. The examination should be conducted 6 weeks prior to the beginning of the season and at the beginning of each new level of competition, unless directed differently by local laws. The correct use of the PSE should screen for signs and symptoms of pathological states that may lead to a nontraumatic death while participating in sports. An effective musculoskeletal examination should detect any postinjury deficits that may lead to subsequent reinjury later in the season. It is our hope that a PSE, based on the literature, can be used to prevent some of the nontraumatic deaths and musculoskeletal injury associated with sports participation.

Cervical Spine and Brachial Plexus Injuries: Return-to-Play Recommendations

Great care is required in managing cervical spine and brachial plexus injuries. Athletes who suffer one or more burners (transient brachial plexus injuries) may return to contact activity when they are asymptomatic and neurologically normal and have full cervical motion. A vertebra displaced horizontally more than 3.5 mm or rotated more than 11 degrees is an absolute contraindication to contact sports. Cervical cord neurapraxia is generally benign, but patients should be counseled about the probability of recurrence, depending on the spinal canal/vertebral body ratio. Unresolved spear tackler's spine is an absolute contraindication to collision sports, as are axial-load teardrop fracture and cervical spine fusion of more than three levels. Spinal cord resuscitation can include blood pressure maintenance and timely methylprednisolone.

Suggested management guidelines for participation in collision activities with congenital, developmental, or postinjury lesions involving the cervical spine

Many conditions involving the cervical spine in the athlete require a management decision. The purpose of this paper is to present appropriate guidelines for return to collision activities in those with congenital, developmental, or post-injury lesions. Information compiled from over 1200 cervical spine lesions documented by the National Football Head & Neck Injury Registry, an extensive literature review, as well as an understanding of injury mechanisms have resulted in reasonable management guidelines. Each of the congenital, developmental, and post-traumatic conditions presented are determined to present either no contraindication, relative contraindication, or an absolute contraindication on the basis of a variety of parameters. Conditions included in the discussion are: odontoid anomalies; spina bifida occulta; atlanto-occipital fusion; Klipple-Feil anomalies; cervical canal stenosis; spear tackler's spine; and traumatic conditions of the upper, middle, and lower cervical spine, including ligamentous injuries and fractures, intervertebral disc injuries, and post-cervical spine fusion. Emphasized is the fact that the proposed guidelines should be used in the decision-making process in conjuction with other factors such as the age, experience, ability of the individual, level of participation, position played, as well as the attitude and desires of the athlete and his parents after an informed discussion of the problem with particular regard to potential risk.

Management guidelines for participation in collision activities with congenital, developmental, or post-injury lesions involving the cervical spine

We believe that the aforementioned management guidelines for participation in collision activities for individuals with congenital, developmental, or postinjury lesions involving the cervical spine have been formulated on the basis of the best information available to date. It is recognized that modifications may occur as more data are collected. We emphasize that these proposed guidelines should be used in the decision-making process in conjunction with such other factors as age, experience, ability of the individual, level of participation, and position played. A most important consideration is the attitude and desire of the individual and his parents following an informed discussion of the problem with particular regard to potential risks.

The relationship of developmental narrowing of the cervical spinal canal to reversible and irreversible injury of the cervical spinal cord in football players

An evaluation of forty-five athletes who had had an episode of transient neurapraxia of the cervical spinal cord revealed a consistent finding of developmental narrowing of the cervical spinal canal. The purpose of the present epidemiological study was to determine the relationship, if any, between a developmentally narrowed cervical canal and reversible and irreversible injury of the cervical cord with use of various cohorts of football players as well as a large control group. Cohort I comprised college football players who were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort II consisted of professional football players who also were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort III was a group of high-school, college, and professional football players who had had at least one episode of transient neurapraxia of the cervical cord. Cohort IV comprised individuals who were permanently quadriplegic as a result of an injury while playing high-school or college football. Cohort V consisted of a control group of male subjects who were non-athletes and had no history of a major injury of the cervical spine, an episode of transient neurapraxia, or neurological symptoms. The mean and standard deviation of the diameter of the spinal canal, the diameter of the vertebral body, and the ratio of the diameter of the spinal canal to that of the vertebral body were determined for the third through sixth cervical levels on the radiographs for each cohort. In addition, the sensitivity, specificity, and positive predictive value of a ratio of the diameter of the spinal canal to that of the vertebral body of 0.80 or less was evaluated. The findings of the present study demonstrated that a ratio of 0.80 or less had a high sensitivity (93 per cent) for transient neurapraxia. The findings also support the concept that symptoms may result from a transient reversible deformation of the spinal cord in a developmentally narrowed osseous canal. The low positive predictive value of the ratio (0.2 per cent) however, precludes its use as a screening mechanism for determining the suitability of an athlete for participation in contact sports. Developmental narrowing of the cervical canal in a stable spine does not appear to predispose an individual to permanent catastrophic neurological injury and therefore should not preclude an athlete from participation in contact sports.

Experimental impact injury to the cervical spine: relating motion of the head and the mechanism of injury

The purpose of this study was to analyze, with use of an impact model, the relationships among motion of the head, local deformations of the cervical spine, and the mechanisms of injury; the model consisted of the head and neck of a cadaver. Traditionally, the mechanisms of injury to the cervical spine have been associated with flexion and extension motions of the head and neck. However, the classification of the mechanisms is not always in agreement with the patient's account of the injury or with lacerations and contusions of the scalp, which indicate the site of the impact of the head. Eleven specimens were dropped in an inverted posture with the head and neck in an anatomically neutral position. Forces, moments, and accelerations were recorded, and the impacts were imaged at 1000 frames per second. The velocity at the time of impact was on the order of 3.2 meters per second. The angle and the padding of the impact surface varied. Observable motion of the head did not correspond to the mechanism of the injury to the cervical spine. Injury occurred 2.2 to 18.8 milliseconds after impact and before noticeable motion of the head. However, the classification of the mechanism of the injuries was descriptive of the local deformations of the cervical spine at the time of the injury. Accordingly, it is a useful tool in describing the local mechanism of injury. Buckling of the cervical spine, involving extension between the third and sixth cervical vertebrae and flexion between the seventh and eight cervical vertebrae, was observed. Other, more complex, buckling deformations were also seen, suggesting that the deformations that occur during impact are so complex that they can give rise to a number of different mechanisms of injury.