Injury to the cervical spine and associated structures as a result of participation in competitive athletics and recreational activities is not uncommon. It appears that the frequency of these various injuries is inversely proportional to their severity. Whereas Albright et al. have reported that 32% of college football recruits sustained“moderate” injuries while in high school (1), catastrophic injuries with associated quadriplegia occur in less than 1/100,000 participants per season at the highschool level(18).
The variety of possible lesions involving the cervical spine is considerable and the severity variable. The literature dealing with the diagnosis and treatment of these problems is considerable. However, conspicuously absent is a comprehensive set of standards or guidelines for establishing criteria for permitting or prohibiting participation in collision activities (boxing, football, ice hockey, lacrosse, rugby, and wrestling) for those with congenital or developmental problems or following injury to the cervical spinal structures. The explanation for this void appears to be twofold. First, the combination of a litigious society and the potential for great harm should things go wrong makes “no” the easiest and perhaps most reasonable advice. Second and perhaps most important, with the exception of the matter of transient quadriplegia, is the lack of credible data pertaining to postinjury risk factors (5). Despite a lack of credible data, this report will attempt to establish management guidelines to assist the clinician in the decision-making process.
Cervical spine conditions requiring a decision as to whether or not participation in collision activities is advisable and safe can be divided into three categories: 1, congenital; 2, developmental; and 3, posttraumatic. Each condition has been determined by the senior author to present eitherno contraindication, relative contraindication or an absolute contraindication on the basis of a variety of parameters.
A condition in which there is no contraindication for participation in collision activities is one where on the basis of experience and existing data there are no associated risk factors. Conditions that constitute an absolute contraindication are those for which, on the basis of experience and existing data, recognized risk factors do exist. With regard to conditions defined as presenting a relative contraindication, several factors apply. First, no recognizable determinants associated with a conclusion of contraindication are present. Second, although not definite, the possibility of recurrence of the injury or the occurrence of a nonpermanent, noncatastrophic injury may exist. Lastly, all individuals including the player, coach, and parents must be aware of and agree to participation where the degree of risk is uncertain.
Information compiled for over 1200 cervical spine injuries documented by the National Football Head and Neck Injury Registry has provided insight into whether various conditions may or may not predispose to more serious injury(16-18). In addition, a review of the literature does in several instances provide significant data for a limited number of specific conditions (5). Analysis of conditions predicated on an understanding of recognized injury mechanisms has permitted categorization on the basis of “educated” conjecture(6,14). Finally, much reliance has been placed on personal experience that must be regarded as anecdotal. Together, these data can be pieced together to allow identification of reasonable management guidelines for participation in collision activities with congenital, developmental, or postinjury lesions involving the cervical spine.
The following proposed guidelines for return to collision activities in the presence of cervical spine abnor malities or following injury are intended only as suggestions. Furthermore, we recognize that other experts in this field may have valid personal experience or data which may not agree with some of these recommendations.
It is important for the clinician to understand that the ultimate decision of whether or not to continue participating in a collision activity rests with the athlete and his parents. Therefore, these guidelines are intended to be used primarily as ancillary educational material to assist in educating the athlete, parents, coaches, athletic trainers, and athletic administrators as well as the clinician as to the risks or potential risks known or suspected with respect to an underlying problem.
The structure and mechanics of the cervical spine enable it to perform three important functions. First, it supports the head as well as the variety of soft tissue structures of the neck. Second, by virtue of segmentation and configuration, it permits multiplanar motion of the head. Third, and most important, it serves as a protective conduit for the spinal cord and cervical nerve roots. Any situation that would either immediately or in the future permanently impede or prevent the performance of any of these three functions in a pain-free manner is unacceptable and contraindicated.
Critical to the application of these guidelines is the implementation of coaching and playing techniques that preclude the use of the head as the initial point of contact in a collision situation. Exposure of the cervical spine to axial loading is an invitation to disaster and relegates any and all safety standards as meaningless(7,11,13,16-18). The following proposed criteria for return to contact activities in the presence of cervical spine abnormalities or following injury are intended only as guidelines.
Hensinger has observed that patients with congenital anomalies of the odontoid are leading a precarious existence. His concern is that a trivial insult superimposed on already weakened or compromised structures may be catastrophic (4). This concern became a reality during the 1989 football season when an 18-year-old high-school player was rendered a respiratory-dependent quadriplegic while making a head tackle that was vividly demonstrated on the game video. Postinjury roentgenograms revealed an os odontoidium with marked C1-C2 instability (Fig. 1). Thus, the presence of odontoid agenesis, odontoid hypoplasia, or os odontoidium is an absolute contraindication to participation in collision activities.
This is a rare condition characterized by partial or complete congenital fusion of the bony ring of the atlas to the base of the occiput. The onset of signs and symptoms are referable to the posterior columns due to cord compression by the posterior lip of the foramen magnum and usually occur in the third or fourth decade. This lesion usually progresses insidiously and slowly, but sudden onset or instant death has been reported. Atlantooccipital fusion as an isolated entity or coexisting with other abnormalities constitutes an absolute contraindication to participation in contact activities.
This is the eponym applied to congenital fusion of two or more cervical vertebrae. For purposes of this discussion, the variety of abnormalities can be divided into two groups: type I mass fusion of the cervical and upper thoracic vertebrae (Fig. 2) and type II fusion of only one or two interspaces (Fig. 3). A variety of associated congenital problems have been identified to be associated with congenital fusion of the cervical vertebrae and include pulmonary, cardiovascular, and urogenital abnormalities. Pizzutillo has pointed out that children with congenital fusion of the cervical spine rarely develop neurological problems or signs of instability (7). However, he further observed that the literature reveals more than 90 cases of neurological problems that developed as a consequence of associated occipital cervical anomalies, late instability, disc disease, or degenerative joint disease. These reports included cervical radiculopathy, spasticity, pain, quadriplegia, and sudden death. Also, more than two-thirds of the neurologically involved patients had single-level fusion of the upper area, whereas many cervical patients with extension fusions of five to seven levels below C3 had no associated neurological loss.
Despite this, the type I lesion, a mass fusion, constitutes anabsolute contraindication to participation in contact sports because of the marked alteration in spinal mechanics possibly predisposing to injury or degenerative changes. As well, a type II lesion with fusion of one or two interspaces with associated limited motion and/or associated occipitocervical anomalies, instability, disc disease, or degenerative changes also constitutes on the basis of Pizzutillo's report an absolute contraindication to participation. On the other hand, type II lesions involving fusion of one or two interspaces at C3 and below in an individual with full cervical range of motion and an absence of occipitocervical anomalies, instability, disc disease, or degenerative changes should present no contraindication.
Developmental Narrowing, (Stenosis) of the Cervical Spine (Transient Quadriplegia)
Subsequent to the description of neurapraxia of the cervical cord with transient quadriplegia, a number of issues concerning the disorder have arisen(10). An epidemiological study performed to address these issues has been recently published (9). Evaluation of 45 athletes who had an episode of transient neurapraxia of the cervical spinal cord revealed the consistent finding of developmental narrowing of the cervical spinal canal. The purpose of the 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 was comprised of 227 college football players who were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort II consisted of 97 professional football players who also were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort III was composed of a group of 45 high-school, college, and professional football players who had at least one episode of transient neurapraxia of the cervical cord. Cohort IV was comprised of 77 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 105 male subjects who were nonathletes and had no history of a major injury of the cervical spine, no episodes 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(Fig. 4). In addition, the sensitivity, specificity, and positive predictive value of the ratio of the diameter of the spinal canal to that of the vertebral body of 0.80 or less was evaluated.
The findings of this study demonstrated that a ratio of 0.80 or less had a high sensitivity (93%) for transient neurapraxia. The findings also support the concept that the symptoms 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%), however, precludes its use as a screening mechanism for determining the suitability of an athlete for participation in contact activities.
Axial load (11,12,17), the degree of instability (11), and the duration from the injury to the reduction (14,15) have been implicated as factors in the occurrence of permanent neurological injury in athletes who play tackle football. None of the 77 quadriplegic individuals (cohort IV) had an episode of neurapraxia of the spinal cord before the catastrophic injury. Also, none of the 45 high-school, college, and professional players who had an episode of transient neurapraxia (cohort III) became quadriplegic. These data, in combination with the absence of developmental narrowing of the cervical canal in the quadriplegic group (cohort IV), provide evidence that the occurrence of transient neurapraxia of the cervical cord and an injury associated with permanent catastrophic neurological sequelae are unrelated(Fig. 5). Therefore, developmental narrowing of the cervical canal in a spine that has no evidence of instability is neither a harbinger of nor a predisposing factor for permanent neurological injury. The data did not reveal an association between developmental narrowing of the cervical canal and quadriplegia (2). The major factor in the occurrence of cervical quadriplegia in football players is a tackling technique in which the head is used as the primary point of contact, with resulting transmission of axial energy to and subsequent failure of, the cervical spine.
The findings of this study demonstrated the high sensitivity, low specificity, and low positive predictive value of the ratio of the diameter of the cervical spinal canal to that of the vertebral body, precluding its use as a screening mechanism for determining the suitability of an individual for participation in contact sports. We believe that developmental narrowing of the cervical canal without associated instability does not predispose an individual to permanent catastrophic neurological injury and, therefore, should not preclude an athlete from participation in contact sports(2).
More recently, a retrospective review was performed of 110 cases of the cervical cord neurapraxia seen in consultation by the senior author(8). Radiographs were measured as described previously, and a new technique with an MS-DOS-based system was developed to measure cord and canal diameters from the magnetic resonance imaging (MRI) scans. All injuries were sports-related, and 86% occurred during football participation. Follow-up evaluation was available for 93 (85%) of the patients after an average of 22 mo. Results of this study indicated that clinical manifestations of the cervical cord neurapraxia patients were paralysis in 36%, weakness in 26%, and sensory changes alone in 38%. Duration of the symptoms for the cervical cord neurapraxia grades were: I, less than 15 min in 73%; II, more than 15 min but less than 24 h in 16%; and III, more than 24 h in 10%. The averages of the sagittal radiologic indices were: 1) Pavlov ratio, 0.69(standard deviation [SD] = 0.11); 2) minimal MRI canal diameter, 9.6 mm (SD = 1.8); 3) cord diameter, 8.1 mm (SD = 0.8); and 4) space available for the cord, 1.6 mm (SD = 1.4). There was no relationship between the various clinical manifestations and the radiologic indices. Overall, 65% of the patients returned to contact sports, with 56% of these patients having at least one recurrence of cervical cord neurapraxia. Patients with recurrence had smaller Pavlov ratios (P < 0.01) and less space available for the cord (P < 0.05).
Based on this statistically significant data, it was concluded that: (a) individuals with uncomplicated cervical cord neurapraxia can be advised to return to play without greater risk of permanent neurological injury, (b) the various clinical manifestations, cervical cord neurapraxia type and grade, are not related to the radiologic indices; and (c) there is a 56% recurrence rate that is correlated with the pathoanatomy, i.e., the smaller the canal, the greater the risk of recurrence.
Guidelines for managing athletes with developmental narrowing of the cervical spine associated with cervical cord neurapraxia are as follows:
- Canal/vertebral body ratio of 0.8 or less in asymptomatic individuals,no contraindication(Figs. 4)
- Ratio of 0.8 or less with one episode of cervical cord neurapraxia,relative contraindication
- Documented episodes of cervical cord neurapraxia associated with intervertebral disc disease and/or degenerative changes, relative contraindication(Figs. 6, 7, and 8)
- Documented episode of cervical cord neurapraxia associated with MRI evidence of cord defect or cord edema, relative/absolute contraindication(Fig. 9)
- Documented episode of cervical cord neurapraxia associated with ligamentous instability, symptoms of neurological findings lasting more than 36 hours, and/or multiple episodes, absolute contraindication.
Spear Tackler's Spine
Spear tackler's spine is a clinical entity that constitutes anabsolute contraindication to participation in tackle football and other collision activities that expose the cervical spine to axial energy inputs (12). A subset of football players were identified who demonstrated: 1) developmental narrowing (stenosis) of the cervical canal; 2) persistent straightening or reversal of the normal cervical lordotic curve on erect lateral roentgenograms obtained in the neutral position; 3) concomitant preexisting posttraumatic roentgenographic abnormalities of the cervical spine; and 4) documentation of having employed spear tackling techniques (Fig. 10). From data obtained by the National Football Head and Neck Injury Registry and the senior author's practice, 15 cases of spear tackler's spine were identified during 1987-1990. All 15 cases were evaluated because of complaints referable to the cervical spine or brachial plexus resulting from football injuries. Of these, 11 had complete neurological recovery without permanent sequelae. Four cases resulted in permanent neurological deficits: quadriplegia, 2; incomplete hemiplegia, 1; and residual long track signs, 1. Permanent neurological injury occurred as the result of axial loading of a persistently straightened cervical spine from use of head-impact playing techniques. We suggest that individuals who possess the aforementioned characteristics of spear tackler's spine be precluded from participation in collision activities that expose the cervical spine to axial energy inputs.
Spina Bifida Occulta
This is a rare, incidental roentgenographic finding that presents no contraindication.
TRAUMATIC CONDITIONS OF THE UPPER CERVICAL SPINE-C1-C2
The anatomy and mechanics of C1-C2 segment of the cervical spine differ markedly from the middle or lower segments. A variety of lesions can occur from the occiput to C3, and their presence should cause concern.
Lesions with any degree of occipital or atlantoaxial instability portend a potentially grave prognosis. Disruption of the transverse and/or alar ligament as manifested by an abnormal atlas-dens interval (ADI) on lateral flexion-extension views constitutes an absolute contraindication to collision activity. (Fig. 11).
Atlantoaxial Rotatory Fixation
Torticollis is frequently associated with a variety of traumatic lesions to the cervical spine. In rare instances it may be associated with a rotatory deformity of the atlantoaxial joint and is usually short-lived and easily correctable. Although an extremely rare condition, torticollis, which is resistant to treatment, may be a manifestation of atlantoaxial rotatory fixation (fixed rotatory subluxation of the atlantoaxial joint)(Fig. 12). This condition may or may not be associated with disruption of the transverse ligament. As pointed out by Fielding and Hawkins, “the importance of recognizing atlantoaxial rotatory deformity lies in the fact that it may indicate a compromised atlantoaxial complex with the potential to cause neural damage or even death”(3). This constitutes an absolute contraindication.
With few exceptions to be mentioned, injuries involving the upper cervical segment that involve a fracture or ligamentous laxity are an absolute contraindication to further participation in collision activities(Figs. 13 and 14).
Healed nondisplaced Jefferson fractures, healed type I and type II odontoid fractures, and healed lateral mass fractures of C2 constitute relative contraindications, providing the patient is pain-free, has a full range of cervical motion, and displays no neurological findings.
In view of the uncertainty of the results of cervical fusion, the gracile configuration of C1, and the importance of the alar and transverse odontoid ligaments, fusion for instability of the upper cervical segment constitutes anabsolute contraindication regardless of how successful the fusion appears roentgenographically.
TRAUMATIC CONDITIONS OF THE MIDDLE AND LOWER CERVICAL SPINE
The criteria of White et al. (19) for defining clinical instability were intended to help establish indications for surgical stabilization. However, although the limits of displacement and angulation correlated with disruption of known structures, no single determinant was considered absolute. In view of the observations of Albright et al. that 9.3%(7 of 75) of the college freshman in his study demonstrated “abnormal motion” as well as on the basis of our own experience, it appears that in many instances some degree of “minor instability” exists in populations of both high-school and college football players without apparent adverse effects (1). The question, of course, becomes, what are the upper limits of “minor instability?” Unfortunately, there are no available data to relate this to the clinical standards. White et al. (19) recognized that the literature is neither always clear nor consistent in describing what constitutes an unstable cervical spine. Using fresh cadaver specimens, they performed load displacement studies on sectioned and unsectioned two-level cervical spine segments to determine the horizontal translation and rotation in the sagittal plane after each ligament was transected. The experiments constituted a quantitative biomechanical analysis of the effects of sectioning ligaments and facet joints on the stability of the cervical spine below C2. The express purpose of the study was to establish indications for surgical stabilization of the unstable spine. Although the intent of the study was to define clinical instability to formulate treatment standards and was not intended to establish criteria for a return to contact athletics, it does appear that their findings are relevant to this latter issue.
White et al. (19) described clinical stability as the ability of the spine to limit its patterns of displacement of physiological loads so as not to damage or irritate the spinal cord or the nerve roots. They further delineated four important findings. First, in sectioning the ligaments, there were small increments of change in stability followed without warning by sudden, complete disruption of the spine under stress. Second, removal of the facets alters the motion segment such that in flexion there is less angular displacement and more horizontal displacement. Third, the anterior ligaments contribute more to stability in extension than the posterior ligaments, and in flexion the posterior ligaments contribute more than the anterior ligaments. The fourth and most relevant finding from the standpoint of parameters for return to contact sports is as follows: The adult cervical spine is unstable, on the brink of instability, when any of the following conditions are present: (a) all of the anterior or all of the posterior elements are destroyed or unable to function; (b) there is more than 3.5 mm horizontal displacement of one vertebra in relationship to an adjacent vertebra measured on lateral resting or flexion-extension roentgenograms(Fig. 15), and/or (c) there is more than 11° of rotation difference to that of either adjacent vertebra measured on a resting lateral or flexion-extension roentgenogram (Fig. 16). Thus, lateral roentgenograms that demonstrate 3.5 mm or more horizontal displacement of one vertebra in relationship to another or 11° or more rotation than either adjacent vertebrae represent an absolute contraindication to further participation in contact activities(Fig. 17). With regard to lesser degrees of displacement and rotation, further participation enters the realm of “trial by battle” and such situations can be considered relative contraindications, depending on such factors as level of performance, physical habits, and position played.
An acute fracture of either the body or posterior elements with or without associated ligamentous laxity constitutes an absolute contraindication to participation. The following healed, stable fractures in an asymptomatic patient who is neurologically normal and has full range of motion can be considered to present no contraindication to participation in contact activities: (a) stable compression fractures of the vertebral body without a sagittal component on anterior/posterior roentgenogram and without involvement of either the ligamentous or posterior bony structures (Fig. 18); (b) a healed stable end plate without a sagittal component on anteroposterior roentgenograms or involvement of the posterior or bony ligamentous structure (Fig. 19); and (c) healed spinous process “clay shoveler” fractures.
Relative contraindications apply to individuals who are asymptomatic, neurologically normal, and have a full pain-free range of cervical motion with the following healed stable fractures (a) stable displaced vertebral body
compression fractures without a sagittal component on anteroposterior roentgenograms; the propensity for these fractures to settle with increased deformity must be considered and carefully followed (Fig. 20), and (b) healed, stable fractures involving the elements of the posterior neural ring in individuals who are asymptomatic, neurologically normal, and have a full pain-free range of cervical motion; in evaluating radiographic and imaging studies to find the location and subsequent healing of posterior neural large fractures, it is important to understand that, as pointed out by Steel (personal communication), a rigid ring cannot break in one location; thus, healing of paired fractures of the ring must be demonstrated (Fig. 21).
An absolute contraindication to further participation in contact activities exists in the presence of the following fractures: (a) vertebral body fracture with a sagittal component (Fig. 22); (b) fracture of the vertebral body with or without displacement with associated posterior arch fractures and/or ligamentous laxity (Fig. 23); (c) comminuted fractures of the vertebral body with displacement into the spinal canal (Figs. 24); (d) any healed fracture of either the vertebral body or posterior components with associated pain, neurological findings, and limitation of normal cervical motion; and (e) healed displaced fractures involving the lateral masses with resulting facet incongruity.
INTERVERTEBRAL DISC INJURY
There is no contraindication to participation in contact activities in individuals with a healed anterior, lateral, or posterior disc herniation treated conservatively (Fig. 25) or those requiring an intervertebral discectomy and interbody fusion for a lateral or central herniation who have a solid fusion, are asymptomatic, neurologically negative, and have a full pain-free range of motion.
A relative contraindication exists in those individuals with either conservatively or surgically treated disc disease with residual facet instability. An absolute contraindication exists in the following situations: (a) acute disc herniation with or without associated neurological findings (Fig. 26); (b) acute herniation or chronic“hard disc” with associated neurological findings, pain, and/or significant limitation of cervical motion; and (c) acute herniation or chronic“hard disc” with associated symptoms of cord neurapraxia due to concomitant congenital narrowing (“stenosis”) of the cervical canal, despite successful one-level fusion (Fig. 27).
STATUS POSTCERVICAL SPINE FUSION
A stable one-level anterior or posterior fusion in a patient who is asymptomatic, neurologically normal, pain-free, and has normal range of cervical motion presents no contraindication to continued participation in contact activities (Fig. 28). Individuals with a stable two-or three-level fusion who are asymptomatic, neurologically normal, and have a pain-free full range of cervical motion present a relative contraindication(Fig. 29). Because of the presumed increased stresses at the articulations of the adjacent uninvolved vertebrae and the propensity for the development of degenerative changes at these levels, it appears to be the rare exception who should be permitted to continue contact activities. In those individuals with more than a three-level anterior or posterior fusion, an absolute contraindication exists as far as continued participation in contact activities is concerned (Fig. 30).
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. To be emphasized, 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 desires of the individual and his or her parents following an informed discussion of the problem with particular regard to potential risks.
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