Injuries to the cervical spine in American football players

Return to Play After Injuries to the Cervical Spine

Return to play (RTP) after sports-related traumatic injuries to the cervical spine is important for athletes and teams, especially at the elite level. While early RTP may be incentivized for athletes and organizations, treating clinicians must have a thorough understanding of cervical spine injuries, treatments, and RTP guidelines to make safe recommendations. In general, patients can RTP when asymptomatic from prior injury with no neurological deficits and a full, painless, active range of motion of the neck. However, injury diagnosis, injury symptoms and severity, history of cervical spine injuries, anatomic variants/anomalies, history of treatment/surgery, and any ongoing or persistent symptoms may modify RTP recommendations. In the current review, we summarize the common cervical spine injuries associated with contact sports and the available guidelines for RTP. It is important to note, however, that despite these guidelines, there is little consensus among treating physicians regarding these recommendations. Therefore, clinical judgment should be used to ensure conservative decisions are made and patient safety is maintained.

Post-traumatic cauda equina concussion: Definition and description of the injury mechanism

Despite being a prevalent clinical condition, cauda equina concussion has not been thoroughly elucidated in the literature. The aim of this study is to delineate the etiology and pathogenesis of cauda equina concussion and its associated clinical manifestations. Patients exhibiting clinical manifestations indicative of spinal cord injury and transient neurological deficits after spinal trauma were evaluated retrospectively. The pathogenesis was elucidated through correlating clinical presentations with radiological findings. Neurological deficits were categorized into two principal groups, symmetrical and asymmetrical. Non-penetrating fractures were classified to ascertain the relationship between the type of trauma and the ensuing neurological deficits. A cohort of 82 patients was diagnosed with cauda equina concussion. Among these, 58 had experienced vertical trauma resulting from falls, while 24 had encountered axial trauma in vehicular accidents. Stable spinal fractures were identified in 52 patients across multiple levels, whereas single-level fractures were observed in 30. Asymmetrical neurological deficits were detected in 51 (62.19%) patients, with a notably higher incidence among those subjected to vertical trauma (p < 0.014). The mean recovery time was 14.25 ± 15.16 h for sensory deficits and 11.25 ± 13.36 h for motor deficits in those patients. Notably, motor deficits resolved more expeditiously than sensory deficits in all cases presenting with both. Cauda equina concussion emerges as a frequently encountered clinical phenomenon attributable to the impact of high-energy vertical forces. Neurological deficits commonly manifest asymmetrically. The rapid resolution of neurological deficits presents challenges for the diagnostic process.

Catastrophic Sports Injuries: Causation and Prevention

➤ Catastrophic injuries in U.S. high school and college athletes are rare but devastating injuries.➤ Catastrophic sports injuries are classified as either traumatic, caused by direct contact during sports participation, or nontraumatic, associated with exertion while participating in a sport.➤ Football is associated with the greatest number of traumatic and nontraumatic catastrophic injuries for male athletes, whereas cheerleading has the highest number of traumatic catastrophic injuries and basketball has the highest number of nontraumatic catastrophic injuries for female athletes.➤ The incidence of traumatic catastrophic injuries for all sports has declined over the past 40 years, due to effective rule changes, especially in football, pole-vaulting, cheerleading, ice hockey, and rugby. Further research is necessary to reduce the incidence of structural brain injury in contact sports such as football.➤ The incidence of nontraumatic catastrophic injuries has increased over the last 40 years and requires additional research and preventive measures. Avoiding overexertion during training, confirming sickle cell trait status in high school athletes during the preparticipation physical examination, and developing cost-effective screening tools for cardiac abnormalities are critical next steps.

Characterizing neck injuries in the national football league: a descriptive epidemiology study

BACKGROUND

Neck injury is a common and often debilitating injury among athletes participating in American football. Limited data exists regarding neck injuries among elite athletes in the National Football League (NFL). To characterize the epidemiology of non-season ending, season-ending, and career-ending neck injuries in the NFL from 2016 through 2021.

METHODS

Athletes who sustained neck injuries were identified using the NFL's injured reserve (IR) list between the 2016 and 2021 seasons. Demographics and return to sport (RTS) data were collected. Available game footages were reviewed to identify the mechanism of injury (MOI). Injury incidence rates were calculated based on per team play basis.

RESULTS

During the 6-year study period, 464 players (mean age 26.8 ± 3.2 years) were placed on the injury reserve list due to neck injuries. There were 285 defensive players and 179 offensive players injured (61.4 vs 38.6%, respectively, p < 0.001). Defensive back was the most common position to sustain a neck injury (111 players, 23.9%). 407 players (87.7%) sustained non-season-ending injuries with a mean RTS at 9.2 ± 11.3 days. 36 players (7.8%) sustained season-ending injuries with a mean RTS at 378.6 ± 162.0 days. 21 players (4.5%) sustained career-ending injuries. The overall incidence of neck injuries was 23.5 per 10,000 team plays. The incidence of season-ending injuries and career-ending injuries were 1.82 and 1.06 per 10,000 team plays, respectively. There were 38 injuries with available footages for MOI assessment (23 non-season-ending, 9 season-ending, 6 career-ending). Head-to-head contact was seen in 15 injuries (39.5%), head-down tackling in 11 injuries (28.9%), direct extremity-to-head contact in 7 injuries (18.4%), and head-to-ground contact in 5 injuries (13.2%). There was no significant difference in age, position, or MOI among players sustaining non-season-ending, season-ending, and career-ending injuries.

CONCLUSION

There is a high incidence of neck injuries among NFL athletes with predictable MOIs including head-to-head contact, head-down tackling, direct extremity-to-head contact, and head-to-ground contact. Defensive players were more likely to sustain neck injuries compared to offensive players. Defensive back was the most common position to sustain a neck injury.

LEVEL OF EVIDENCE

III.

Congenital Cervical Stenosis: a Review of the Current Literature

PURPOSE OF REVIEW

Congenital cervical stenosis (CCS) is a phenomenon in which an individual has a narrow canal due to abnormal anatomy which can present with earlier degenerative symptoms due to a reduced sagittal diameter. The diagnosis of CCS is important to individual treatment and preventative measures. Often, athletes are warned against sport participation that may cause damage to the cervical spine. There may be a predisposition in certain populations, but lack of data limits conclusions. The current review investigates recent literature on the definition, pathoanatomy, clinical presentation, and management of CCS. It specifically interrogates potential populations predisposed to this condition.

RECENT FINDINGS

The current literature reveals a potential predisposition for CCS in the black population when compared to the white population; however, many studies do not report race when discussing CCS patients. The lack of data limits a consensus on specific populations with a congenitally narrow canal. CCS may be more prevalent in specific populations. With knowledge of populations more at risk for this condition, physicians and teams can be alert when evaluating players and young adults. Furthermore, this may provide insight into risk for symptoms with degenerative disease. These findings introduce an avenue for further research into CCS.

Sport-related Structural Brain Injury in High School and College American Football Athletes, 2002-2020: Effect of Lystedt Law

BACKGROUND

A previous report revealed an average of 7.2 (0.67 per 100,000 participants) sport-related structural brain injuries (SRSBIs) with macroscopic lesions per year in high school (HS) and college football players. The Lystedt law and other rule changes have been implemented with intent to reduce the risk of brain injury in football.

HYPOTHESIS

To update the profile of SRSBIs in HS and college football players and evaluate the efficacy of legislation intended to reduce brain injuries.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 4.

METHODS

We retrospectively reviewed 18 academic years (July 2002 through June 2020) of SRSBIs catalogued by the National Registry of Catastrophic Sports Injuries. The incidence of SRSBIs was assessed at the HS level during the pre (July 2002 through June 2009), transitional (July 2009 through June 2014), and post (July 2014 through June 2020) universal adoption time periods of the Lystedt law. In addition, the incidence of SRSBIs during the second half of the study (2011-2012 through 2019-2020) was compared with the first half of the study (2002-2003 through 2010-2011).

RESULTS

During the study period, there was a total of 228 SRSBIs (12.7 per year, 1.01 per 100,000 participants): 212 (93%, 11.8 per year, 1.00 per 100,000) in HS athletes and 16 (7%, 0.89 per year, 1.17 per 100,000) in college athletes. There were 52 fatalities (2.9 per year, 0.22 per 100,000 participants) with 46 (2.56 per year, 0.22 per 100,000) in HS athletes and 6 (0.33 per year, 0.43/100,000) in college athletes. There was no significant difference in risk of HS total SRSBIs or fatalities during the 3 Lystedt periods. The risk of combined SRSBI cases [relative risk (RR) = 1.22, P = 0.13] and fatalities (RR = 1.20, P = 0.52) was similar in the second half of the study compared with the first half of the study.

CONCLUSION

Despite implementation of rule changes intended to reduce head injury, in particular the Lystedt law, the incidence of SRSBIs has remained unchanged. Further research is necessary to develop effective prevention programs for SRSBIs.

CLINICAL RELEVANCE

SRSBIs remain a persistent problem in HS and college American football. The recent head injury rule changes have not been effective at reducing SRSBIs.

At-Risk Tackling Techniques and Effectiveness in NCAA Division I Collegiate Football

Background

Head-down tackling has been associated with injuries to the brachial plexus, cervical spine, and head in high school and collegiate American football. Head-down tackling has also been associated with decreased effectiveness in successful tackles compared with head-up tackling.

Purpose

To assess tackling techniques used during National Collegiate Athletic Association (NCAA) Division I football games and to evaluate the successful tackling rates according to technique.

Study Design

Cross-sectional study.

Methods

Three reviewers analyzed 1000 consecutive solo defensive tackling attempts made in the 2021 season (October to December) by 8 universities within the NCAA Southeastern Conference. Slow-motion replays were used to analyze the success of the tackling attempt, the tackling method, and the initial point of contact with respect to the offensive player's waist. The chi-square or Fisher exact test was used to analyze categorical data, and the 2-tailed Student t-test or the Mann-Whitney U test was used to analyze continuous data.

Results

Head-up and head-down tackling occurred in 902 (90.2%) and 98 (9.8%) tackle attempts, respectively. Head-up tackles were successful in 76.2% of the attempts compared with 55.1% for head-down tackles (P < .001). Tackles were made at or above the offensive player's waist in 777 (77.7%) attempts and below the waist in 223 (22.3%) attempts. Tackles at or above the waist were successful in 77.6% of the attempts compared with 61.9% of tackles below the waist (P < .001). The inside-shoulder method was used in 592 (59.2%) tackles, the arm method in 317 (31.7%), the head-across-the-bow method in 72 (7.2%), and the helmet-to-helmet method in 19 (1.9%). Inside-shoulder tackles had the highest success rate of 93.2%, compared with 41.6% for arm (P < .001), 59.7% for head-across-the-bow (P < .001), and 73.7% for helmet-to-helmet (P = .001) tackles. Inside-shoulder tackles resulted in head-up tackling in 92.9% compared with 41.7% for head-across-the-bow (P < .001) and 57.9% for helmet-to-helmet (P < .001) tackles. There were no recorded injuries to the tackler.

Conclusion

Head-up tackles, tackles made at or above the offensive player's waist, and inside-shoulder tackles had the highest success rates. Head-down tackling and tackling below the waist were associated with poor tackling methods, including head-across-the-bow and helmet-to-helmet tackles, which had lower success rates.

Acute and Emergent Spinal Injury Assessment and Treatment

Sports participation is a leading cause of catastrophic cervical spine injury (CSI) in the United States. Appropriate prehospital care for athletes with suspected CSIs should be available at all levels of sport. Planning the process of transport for home venues before the start of the season and ensuring that a medical time out occurs at home and away games can reduce complications of transport decisions on the field of play and expedite transport of the spine-injured athlete.

Musculoskeletal Injury in American Football: A Bibliometric Analysis of the Most Cited Articles

Background

Textbook knowledge and clinical dogma are often insufficient for effective evidence-based decision making when treating musculoskeletal injuries in American football players, given the variability in presentation and outcomes across different sports and different levels of competition. Key evidence can be drawn directly from high-quality published articles to make the appropriate decisions and recommendations for each athlete's unique situation.

Purpose

To identify and analyze the 50 most cited articles related to football-related musculoskeletal injury to provide an efficient tool in the arsenal of trainees, researchers, and evidence-based practitioners alike.

Study Design

Cross-sectional study.

Methods

The ISI Web of Science and SCOPUS databases were queried for articles pertaining to musculoskeletal injury in American football. For each of the top 50 most cited articles, bibliometric elements were evaluated: citation count and density, decade of publication, journal, country, multiple publications by the same first author or senior author, article content (topic, injury area), and level of evidence (LOE).

Results

The mean ± SD number of citations was 102.76 ± 37.11; the most cited article, with 227 citations, was "Syndesmotic Ankle Sprains" published in 1991 by Boytim et al. Several authors served as a first or senior author on >1 publication, including J.S. Torg (n = 6), J.P. Bradley (n = 4), and J.W. Powell (n = 4). The American Journal of Sports Medicine published the majority of the 50 most cited articles (n = 31). A total of 29 articles discussed lower extremity injuries, while only 4 discussed upper extremity injuries. The majority of the articles (n = 28) had an LOE of 4, with only 1 article having an LOE of 1. The articles with an LOE of 3 had the highest mean citation number (133.67 ± 55.23; F = 4.02; P = .05).

Conclusion

The results of this study highlight the need for more prospective research surrounding the management of football-related injury. The low overall number of articles on upper extremity injury (n = 4) also highlights an area for further research.

Return to Martial Arts after Surgical Treatment of the Cervical Spine: Case Report and Systematic Review of the Literature for an Evidence-Based Approach

Background: Cervical spine injuries are considered common in athlete populations, especially in those involved in high-contact sports. In some cases, surgical treatment can be necessary, and, therefore, return-to-play (RTP) after surgery represent a notable issue. Methods: We performed a systematic review of literature according to the PRISMA statement guidelines using the following search algorithm: (("ACDF") OR ("cervical spine surgery") OR ("neck surgery") OR ("cervical discectomy") OR ("foraminotomy") OR ("cervical disc replacement")) AND (("return to play") OR ("athlete") OR ("contact sports") OR ("martial arts")). The search was performed on 21 October 2022. We included only articles in which operative treatment for the cervical spine was performed and return to martial art activity was declared in the text. Results: Eight articles were selected, including 23 athletes who practice wrestling (n = 16), kickboxing (n = 1), sumo (n = 1) or other unspecified martial arts (n = 5). We also included the case of a young judoka who underwent anterior cervical discectomy and fusion (ACDF) at our hospital. About 88% (21 of 24 cases) of martial arts practitioners returned to play after cervical spine surgery, and no major complications were reported after RTP. Four patients (16.7%) returned in 0-3 months; 41.7% (10 of 24) returned in 3-6 months; 29.2% (7 of 24) returned after a period longer than 6 months. ACDF is the most used procedure. The level of evidence in the included articles is low: only case reports are available, including some single-case studies. Moreover, a small number of cases have been reported, and the examined data are very heterogeneous. Conclusions: Return to martial arts within one year after cervical spine surgery is generally safe, even if case-by-case evaluation is, however, necessary. Further studies are necessary to corroborate the present findings in a larger population.

Management of Acute Subaxial Trauma and Spinal Cord Injury in Professional Collision Athletes

Sports-related acute cervical trauma and spinal cord injury (SCI) represent a rare but devastating potential complication of collision sport injuries. Currently, there is debate on appropriate management protocols and return-to-play guidelines in professional collision athletes following cervical trauma. While cervical muscle strains and sprains are among the most common injuries sustained by collision athletes, the life-changing effects of severe neurological sequelae (ie, quadriplegia and paraplegia) from fractures and SCIs require increased attention and care. Appropriate on-field management and subsequent transfer/workup at an experienced trauma/SCI center is necessary for optimal patient care, prevention of injury exacerbation, and improvement in outcomes. This review discusses the epidemiology, pathophysiology, clinical presentation, immediate/long-term management, and current return-to-play recommendations of athletes who suffer cervical trauma and SCI.

Influence of Axial Load and a 45-Degree Flexion Head Position on Cervical Spinal Stiffness in Healthy Young Adults

Background: Neck pain is a major cause of disability worldwide. Poor neck posture such as using a smartphone or work-related additional cervical axial load, such headgear of aviators, can cause neck pain. This study aimed at investigating the role of head posture or additional axial load on spinal stiffness, a proxy measure to assess cervical motor control. Methods: The posterior-to-anterior cervical spinal stiffness of 49 young healthy male military employees [mean (SD) age 20 ± 1 years] was measured in two head positions: neutral and 45-degree flexed head position and two loading conditions: with and without additional 3 kg axial load. Each test condition comprised three trials. Measurements were taken at three cervical locations, i.e., spinous processes C2 and C7 and mid-cervical (MC). Results: Cervical spinal stiffness measurements showed good reliability in all test conditions. There was a significant three-way interaction between location × head position × load [F(2, 576) = 9.305, p < 0.001]. Significant two-way interactions were found between measurement locations × loading [F(2, 576) = 15.688, p < 0.001] and measurement locations × head position [F(2, 576) = 9.263, p < 0.001]. There was no significant interaction between loading × head position [F(1, 576) = 0.692, p = 0.406]. Post hoc analysis showed reduction of stiffness in all three measurement locations in flexion position. There was a decrease in stiffness in C2 with loading, increase in stiffness in C7 and no change in MC. Discussion: A flexed head posture leading to decreased stiffness of the cervical spine might contribute to neck pain, especially if the posture is prolonged and static, such as is the case with smartphone users. Regarding the additional load, stiffness decreased high cervical and increased low cervical. There was no change mid cervical. The lower spinal stiffness at the high cervical spine might be caused by capsular ligament laxity due to the buckling effect. At the lower cervical spine, the buckling effect seems to be less dominant, because the proximity to the ribs and sternum provide additional stiffness.

Effects of increasing axial load on cervical motor control

To investigate the effects of increasing axial load on cervical motor control. Surrogates of cervical motor control were active cervical range of motion (C-ROM) and joint position error (JPE) assessed in flexion, extension, lateroflexion and rotation directions in 49 healthy young men (mean age: 20.2 years). All measurements were executed with 0-, 1-, 2-, and 3-kg axial loads. Linear mixed models were used to assess the effects of axial loading and cervical movement-direction on C-ROM and JPE. Post-hoc analysis was performed to compare load levels. Axial loading (p = 0.045) and movement direction (p < 0.001) showed significant main effects on C-ROM as well as an interaction (p < 0.001). C-ROM significantly changed with 3-kg axial load by decreaseing extension (− 13.6%) and increasing lateroflexion (+ 9.9%). No significant main effect was observed of axial loading on JPE (p = 0.139). Cervical motor control is influenced by axial loading, which results in decreased C-ROM in extension and increased C-ROM lateroflexion direction.

The importance of intervertebral disc material model on the prediction of mechanical function of the cervical spine

BACKGROUND

Linear elastic, hyperelastic, and multiphasic material constitutive models are frequently used for spinal intervertebral disc simulations. While the characteristics of each model are known, their effect on spine mechanical response requires a careful investigation. The use of advanced material models may not be applicable when material constants are not available, model convergence is unlikely, and computational time is a concern. On the other hand, poor estimations of tissue's mechanical response are likely if the spine model is oversimplified. In this study, discrepancies in load response introduced by material models will be investigated.

METHODS

Three fiber-reinforced C2-C3 disc models were developed with linear elastic, hyperelastic, and biphasic behaviors. Three different loading modes were investigated: compression, flexion and extension in quasi-static and dynamic conditions. The deformed disc height, disc fluid pressure, range of motion, and stresses were compared.

RESULTS

Results indicated that the intervertebral disc material model has a strong effect on load-sharing and disc height change when compression and flexion were applied. The predicted mechanical response of three models under extension had less discrepancy than its counterparts under flexion and compression. The fluid-solid interaction showed more relevance in dynamic than quasi-static loading conditions. The fiber-reinforced linear elastic and hyperelastic material models underestimated the load-sharing of the intervertebral disc annular collagen fibers.

CONCLUSION

This study confirmed the central role of the disc fluid pressure in spinal load-sharing and highlighted loading conditions where linear elastic and hyperelastic models predicted energy distribution different than that of the biphasic model.

The Prevalence and Management of Stingers in College and Professional Collision Athletes

PURPOSE OF REVIEW

Particularly common in collision sports such as American football or rugby, stingers are a traumatic transient neuropraxia of a cervical nerve root(s) or brachial plexus that may last anywhere from minutes to hours. This review summarizes the knowledge on the diagnosis and management of stingers in college and professional collision athletes by providing an overview of their epidemiology and pathophysiology, followed by a discussion on current treatment guidelines and return-to-play recommendations.

RECENT FINDINGS

Despite modifications to tackling technique, increasing awareness, and various equipment options, American football continues to have a high rate of cervical spine injuries, the majority of which occur in preseason and regular season competition settings. The incidence of stingers has slowly increased among collision athletes, and nearly half of all players report sustaining at least one stinger in their career. Recent studies have shown certain anatomical changes in the cervical spine are related to acute and reoccurring stingers. Most players who experience stingers do not miss practices or games. Despite their prevalence, literature highlighting the impact of stingers on college and professional collision athletes is limited. Advances in imaging modalities and novel radiographic parameters have provided tools for screening athletes and can guide return-to-play decisions. Future research regarding appropriate screening practices for athletes with reoccurring stingers, use of protective equipment, and rehabilitation strategies are needed to identify predisposing factors, mitigate the risk of injury, and restore full functional strength and ability.

Nationwide sports injury prevention strategies: A scoping review

National strategies to prevent sports injuries can potentially improve health outcomes at a population level and reduce medical costs. To date, a compilation of the strategies that countries have attempted, and their effectiveness, does not exist. This scoping review sets out to: identify nationwide attempts at implementing sports injury prevention strategies; examine the impact of these strategies; and map them onto the Translating Research into Injury Prevention Practice (TRIPP) framework. Using Levac's scoping review method, we: (a) identified the research questions, (b) identified relevant studies, (c) identified the study selection criteria, (d) charted the data, and (e) reported the results. A search of MEDLINE, Scopus, SPORTDiscus, CINAHL, and Web of Science databases for articles published pre-June 2019 was conducted. We identified 1794 studies and included 33 studies (of 24 strategies). The USA (n = 7), New Zealand (n = 4), Canada (n = 3), the Netherlands (n = 3), Switzerland (n = 2), Belgium (n = 1), France (n = 1), Ireland (n = 1), South Africa (n = 1), and Sweden (n = 1) have implemented nationwide sports injury prevention strategies with 29 (88%) of the included studies demonstrating positive results. Mapping the strategies onto the TRIPP framework highlighted that only four (17%) of the 24 included strategies reported on the implementation context (TRIPP Stage 5), suggesting an important reporting gap. Nationwide sports injury prevention efforts are complex, requiring a multidimensional approach. Future research should report intervention implementation data; examine the implementation context early in the research process to increase the likelihood of real-world implementation success; and could benefit from incorporating qualitative or mixed research methods.

Nontraumatic Exertional Fatalities in Football Players, Part 1: Epidemiology and Effectiveness of National Collegiate Athletic Association Bylaws

BACKGROUND

Football has the highest number of nontraumatic fatalities of any sport in the United States.

PURPOSE

To compare the incidence of nontraumatic fatalities with that of traumatic fatalities, describe the epidemiology of nontraumatic fatalities in high school (HS) and college football players, and determine the effectiveness of National Collegiate Athletic Association (NCAA) policies to reduce exertional heat stroke (EHS) and exertional sickling (ES) with sickle cell trait (SCT) fatalities in athletes.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We retrospectively reviewed 20 academic years (1998-2018) of HS and college nontraumatic fatalities in football players using the National Registry of Catastrophic Sports Injuries (NRCSI). EHS and ES with SCT fatality rates were compared before and after the implementation of the NCAA football out-of-season model (bylaw 17.10.2.4 [2003]) and NCAA Division I SCT screening (bylaw 17.1.5.1 [2010]), respectively. Additionally, we compiled incidence trends for HS and college traumatic and nontraumatic fatalities in football players for the years 1960 through 2018 based on NRCSI data and previously published reports.

RESULTS

The risk (odds ratio) of traumatic fatalities in football players in the 2010s was 0.19 (95% CI, 0.13-0.26; P < .0001) lower in HS and 0.29 (95% CI, 0.29-0.72; P = .0078) lower in college compared with that in the 1960s. In contrast, the risk of nontraumatic fatalities in football players in the 2010s was 0.7 (95% CI, 0.50-0.98; P = .0353) in HS and 0.9 (95% CI, 0.46-1.72; P = .7413) in college compared with that in the 1960s. Since 2000, the risk of nontraumatic fatalities has been 1.89 (95% CI, 1.42-2.51; P < .001) and 4.22 (95% CI, 2.04-8.73; P < .001) higher than the risk of traumatic fatalities at the HS and college levels, respectively. During the 20 years studied, there were 187 nontraumatic fatalities (average, 9.4 per year). The causes of death were sudden cardiac arrest (57.7%), EHS (23.6%), ES with SCT (12.1%), asthma (4.9%), and hyponatremia (1.6%). The risk of a nontraumatic fatality was 4.1 (95% CI, 2.8-5.9; P < .0001) higher in NCAA compared with HS athletes. There was no difference in the risk of an EHS fatality in NCAA athletes (0.86 [95% CI, 0.17-4.25]; P = .85) after implementation in 2003 of the NCAA football out-of-season model. The risk of an ES with SCT fatality in Division I athletes was significantly lower after the 2010 NCAA SCT screening bylaw was implemented (0.12 [95% CI, 0.02-0.95]; P = .04).

CONCLUSION

Since the 1960s, the risk of nontraumatic fatalities has declined minimally compared with the reduction in the risk of traumatic fatalities. Current HS and college nontraumatic fatality rates are significantly higher than rates of traumatic fatalities. The 2003 NCAA out-of-season model has failed to significantly reduce EHS fatalities. The 2010 NCAA SCT screening bylaw has effectively prevented ES with SCT fatalities in NCAA Division I football.

At-Risk Tackling Techniques in American Football

Background

In American football, fewer fatalities and severe injuries have been seen annually since 1976, after data from 1971 through 1975 were retrospectively reviewed to better understand the mechanisms involved in catastrophic cervical spine injury and rules were enacted to prohibit certain types of aggressive tackling. The National Football Head and Neck Injury Registry was established in 1975.

Purpose

To assess (1) tackling techniques that coaches were teaching at 3 levels-youth level (YL; 4th to 5th grades), middle school (MS; 6th to 8th grades), and high school (HS; 9th to 12th grades); (2) tackling techniques used during games; and (3) the successful tackle rates of these techniques.

Study Design

Descriptive epidemiology study.

Methods

Surveys were distributed via email to 500 coaches of YL, MS, and HS football teams in Texas. Coaches provided video recordings of football games, and all tackle attempts were graded by a single reviewer who watched game videos; 1000 consecutive tackles were observed for each group. Survey data included how coaches instructed their players to tackle, the types of tackles, the number of tackles versus missed tackles, the head position, and the initial contact. Data were analyzed with the chi-square test. A subset of 100 consecutive tackles at each level of play was reviewed by 2 blinded reviewers to assess intra- and interrater reliabilities.

Results

In all groups, coaches responded that they preferred to teach the at-risk "head across the bow" tackling technique (83% YL, 81% MS, 75% HS). Coaches stated that they instructed players to "keep your head up," as currently recommended, 89% in YL, 100% in MS, and 81% in HS. During games, players used head-up, inside-shoulder tackles more successfully across all groups (97.5% YL, 99.5% MS, 98.8% HS). While intra- and interrater reliabilities were in the good range, these scores were lower in the youth group.

Conclusion

Our study supports the effectiveness of tackling with the head up and making the initial contact with the inside shoulder. Lower reliability ratings for the youth group were likely due to lower video quality and the lack of players' tackling experience.

A helmetless-tackling intervention in American football for decreasing head impact exposure: A randomized controlled trial

OBJECTIVES

To evaluate a behavioral intervention to reduce head impact exposure in youth playing American football.

DESIGN

Nested randomized controlled trial.

METHODS

Participants, ages 14-17 years, wore head impact sensors (SIM-G™) during two seasons of play. Those randomized to the intervention group underwent weekly tackling/blocking drills performed without helmets (WoH) and shoulder pads while the control group trained as normal, matching frequency and duration. Research personnel provided daily oversight to maintain fidelity. Head impact frequency (≥10g) per athlete exposure (ImpAE) was analyzed over time (two 11-week seasons) using mixed effect models or ANCOVA. Secondary outcomes included exposure-type (training, game) and participation level (entry-level versus upper-level secondary education).

RESULTS

One-hundred fifteen participants (59 WoH, 56 control) met compliance criteria, contributing 47,382 head impacts and 10,751 athlete exposures for analysis. WoH had fewer ImpAE during games compared to control participants at weeks 4 (p=0.0001 season 1, p=0.0005 season 2) and 7 (p=0.0001 both seasons). Upper-level WoH participants had less ImpAE during games than their matched controls at weeks 4 (p=0.017 and p=0.026) and 7 (p=0.037 and p=0.014) in both seasons, respectively. Upper-level WoH also had fewer ImpAE during training at week 7 (p=0.015) in season one.

CONCLUSIONS

Tackling and blocking drills performed without a helmet during training reduced the frequency of head impacts during play, especially during games. However, these differences disappeared by the end of the season. Future research should explore the frequency of behavioral intervention and a dose-response relationship considering years of player experience.

TRIAL REGISTRATION

ClinicalTrials.gov # NCT02519478.

A novel helmet-mounted device for reducing the potential of catastrophic cervical spine fractures and spinal cord injuries in head-first impacts

BACKGROUND

Head-first impacts with an aligned cervical spine cause some of the most severe types of injuries due to the risk of fractures and associated spinal cord injury. Sports, such as football, mountain biking and horseback riding, contribute to the incidence of spinal cord injury but there is potential to reduce the risk of these injuries through a helmet-mounted device.

METHODS

A novel device, the Pro-Neck-Tor mechanism, was incorporated into a commercial football helmet and tested in head-first impact experiments. The Pro-Neck-Tor connects an inner and outer helmet shell, which upon head-first impact of a certain load, induces motion of the head away from the path of the following torso. Impacts were performed onto three impact surface angles with a flexion-inducing Pro-Neck-Tor mechanism.

FINDINGS

Based on averaged data, the Pro-Neck-Tor provided a significant and consistent reduction in peak compressive neck forces compared to the unmodified football helmet in the conditions tested. In some impact conditions, the Pro-Neck-Tor increased the peak sagittal plane neck bending moments and impulse over that observed for the unmodified helmet.

INTERPRETATION

The Pro-Neck-Tor with flexion escape is capable of lowering axial neck forces in head-first impacts compared to a conventional helmet by guiding the cervical column away from an aligned posture and into an eccentric loading scenario which published studies suggests frequently leads to no injury or to a less severe injury. Continued development and testing of the device are needed to optimize the altered neck loading and to drive the design toward a commercial configuration.

A novel Cervical Spine Protection device for reducing neck injuries in contact sports: design concepts and preliminary in vivo testing

Head and neck injuries are common in contact sports such as American football. Different mechanisms can produce such injuries, including compressive impact forces on the crown of the helmet with the neck in a flexed chin-down position. The aim of this paper was developing and testing a novel Cervical Spine Protection Device (CSPD) designed to keep the neck within its safe physiological range. The cervical spine range of motion (ROM) of ten participants was measured under four conditions: free; wearing a football gear; wearing the CSPD; and wearing the CSPD underneath the gear. The CSPD was tested in terms of passive and active restraint of head motion, and for its capability to improve endurance time of the neck extensor muscles. Wearing the CSPD resulted in a significant 40-60% reduction in ROM across the three anatomical planes, and in increased endurance of the neck extensor muscles (FREE: 114 ± 57 s; CSPD: 214 ± 95 s; p = 0.004). In quasi-static loading conditions the CSPD was capable of keeping the neck within its physiological range, thus it may be used to decrease the risk of severe injuries due to dangerous chin-down positions.

Spinal Concussion in Adults: Transient Neuropraxia of Spinal Cord Exposed to Vertical Forces

OBJECTIVE

The aim of the study is to discuss along with literature knowledge the post-traumatic clinical progression of cases with symptoms of transient spinal cord impact and cases of spinal concussion following exposure of the vertebral column to vertical forces.

MATERIALS AND METHODS

A total of 43 cases, all falls from height, were diagnosed with spinal concussion. It was determined that the vertebral column had been exposed to the effects of vertical forces, and the spinal cord had been affected by vertical forces. In all cases, spinal magnetic resonance imaging and dynamic X-ray examinations were performed at the time of admission. Clinical symptoms of the cases were recorded by scoring based on the Torg Grading System.

RESULTS

Cases were started on conservative treatment because radiologic symptoms that would explain the clinical symptoms could not be detected. Most frequently encountered were the neurologic symptoms related to the upper thoracic and lower cervical segments being affected. In 7 cases, urinary incontinence was also detected. Symptoms related to the spinal cord being affected were completely recovered in 1-3 days in all cases.

CONCLUSION

As a result of the vertebral column being affected by vertical forces, the most frequently affected are the thoracic segments of the spinal cord. These cases show similarities to real spinal cord injury without radiographic abnormality cases when evaluated along with clinical and radiologic symptoms. Absolute differential diagnosis from real spinal cord injury without radiographic abnormality cases cannot be made until total neurologic recovery takes place.

The Effect of Head Impact Location on Day of Diagnosed Concussion in College Football

INTRODUCTION

Scientists and clinicians have attempted to identify and understand biomechanical factors that influence concussion likelihood. The effect of impact frequency to a given head location before the concussion has not been evaluated. The purpose of this study was to compare the frequency of impacts to a given head location on days of diagnosed concussion to the frequency of impacts to a given head location before kinematically matched nonconcussive impacts.

METHODS

Head impact data were gathered from 33 Division I National Collegiate Athletic Association football players. Twenty-four concussions were identified and matched with impacts of similar kinematic and injury criterion values (linear acceleration, rotational acceleration, Gadd severity index, and head injury criterion) that occurred during the same event type (game, practice, or scrimmage). In addition, these same matching criteria were used to match all players to the closest kinematic/same player group. All impacts within a session before the impact of interest (concussive or matched impact) were analyzed.

RESULTS

On days of diagnosed concussion, the concussive group sustained a lower percentage of impacts to the front of the head (34.5%) and a greater frequency of impacts to the sides (19.6%) and top (18.9%) of the head (χ(3) = 10.23, P = 0.017) as compared with the matched nonconcussive group (front = 42.5%, sides = 16.6%, top = 14.0%). No significant difference in frequency was found in impacts to the back of the head.

CONCLUSION

It may be more difficult to mitigate concussive forces sustained in impacts to the top and sides of the head than the front of the head. These findings fall in line with previous research demonstrating that reduced impact magnitudes may lessen concussion risk. Studying appropriate training paradigms to develop safer playing techniques on the field is warranted.

Return to Play in Elite Contact Athletes After Anterior Cervical Discectomy and Fusion: A Meta-Analysis

STUDY DESIGN

Systematic literature review and meta-analysis of studies published in English language.

OBJECTIVE

Return to play after anterior cervical discectomy and fusion (ACDF) in contact athletes remains a controversial topic with no consensus opinion in the literature. Additional information is needed to properly advise and treat this population of patients. This study is a meta-analysis assessing return to competitive contact sports after undergoing an ACDF.

METHODS

A literature search of Medline, Embase, and Cochrane Reviews was performed to identify investigations reporting return to play following ACDF in professional contact athletes. The pooled results were performed by calculating the effect size based on the logic event rate. Studies were weighted by the inverse of the variance, which included both within and between-study error. Confidence intervals (CIs) were reported at 95%. Heterogeneity was assessed using the Q statistic and I². Sensitivity analysis and publication bias calculations were performed.

RESULTS

The initial literature search resulted in 166 articles, of which 5 were determined relevant. Overall, return to play data was provided for 48 patients. The pooled clinical success rate for return to play was 73.5% (CI = 56.7%, 85.8%). The logit event rate was calculated to be 1.036 (CI = 0.270, 1.802), which was statistically significant (P = .008). The studies included in this meta-analysis demonstrated minimal heterogeneity with Q value of 4.038 and I² value of 0.956.

CONCLUSIONS

Elite contact athletes return to competition 73.5% of the time after undergoing ACDF. As this is the first study to pool results from existing studies, it provides strong evidence to guide decision making and expectations in this patient population.

Recurrent stingers in an adolescent American football player: dilemmas of return to play. A case report and review of the literature

We present the case of a 16-year-old football linebacker with a history of recurrent stingers. Initial physical examination was normal as were cervical spine radiographs. MRI of the cervical spine revealed relative stenosis. Electrodiagnostic testing revealed chronic bilateral neurogenic changes of the superior trunk of the brachial plexus. A Kerr Collar was obtained to minimize head acceleration and force transmission through the neck. While there are return-to-play guidelines for recurrent stingers, there are inconsistencies with those recommendations. Our case highlights the challenges in contact sport athletes with recurrent stingers.

Return to play in athletes with spinal cord concussion: a systematic literature review

STUDY DESIGN

This is a systematic review.

PURPOSE

The study aimed to evaluate whether spinal cord concussion (SCC) patients can safely return to play sports and if there are factors that can predict SCC recurrence or the development of a spinal cord injury (SCI).

BACKGROUND CONTEXT

Although SCC is a reversible neurologic disturbance of spinal cord function, its management and the implications for return to play are controversial.

METHODS

We conducted a systematic search of the literature using the keywords Cervical Spine AND Sports AND Injuries in six databases. We examined return to play in patients (1) without stenosis, (2) with stenosis, and (3) who underwent single-level anterior cervical discectomy and fusion (ACDF). We also investigated predictors for the risk of SCC recurrence or SCI.

RESULTS

We identified 3,655 unique citations, 16 of which met our inclusion criteria. The included studies were case-control studies or case series and reports. Two studies reported on patients without stenosis: pediatric cases returned without recurrence, whereas an adult case experienced recurrent SCC after returning to play. Seven studies described patients with stenosis. These studies included cases with and without recurrence after return to play, as well as patients who suffered SCI with permanent neurologic deficits. Three studies reported on patients who underwent an ACDF. Although some patients played after surgery without problems, several patients experienced recurrent SCC due to herniation at levels adjacent to the surgical sites. With respect to important predictors, a greater frequency of patients who experienced recurrence of symptoms or SCI following return to play had a "long" duration of symptoms (>24 hours; 36.36%) compared with those who were problem-free (11.11%; p=.0311).

CONCLUSIONS

There is limited evidence on current practice standards for return to play following SCC and important risk factors for SCC recurrence or SCI. Because of small sample sizes, future prospective multicenter studies are needed to determine important predictive factors of poor outcomes following return to play after SCC.

Mechanisms and Factors Associated With Tackle-Related Injuries in South African Youth Rugby Union Players

BACKGROUND

The majority of injuries in rugby union occur during tackle events. The mechanisms and causes of these injuries are well established in senior rugby union.

PURPOSE

To use information from an injury database and assess video footage of tackle-related injuries in youth rugby union matches to identify environmental factors and mechanisms that are potentially confounding to these injuries.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

Injury surveillance was conducted at the under-18 Craven Week rugby tournament. Tackle-related injury information was used to identify injury events in match video footage (role-matched noninjury tackle events were identified for the cohort of injured players). Events were coded using match situational variables (precontact, contact, and postcontact). Relative risk ratio (RRR; ratio of probability of an injury or noninjury outcome occurring when a characteristic was observed) was reported by use of logistic regression.

RESULTS

In comparison with the first quarter, injury risk was greater in the third (RRR = 9.75 [95% CI, 1.71-55.64]; P = .010) and fourth quarters (RRR = 6.97 [95% CI, 1.09-44.57]; P = .040) for ball carriers and in the fourth quarter (RRR = 9.63 [95% CI, 1.94-47.79]; P = .006) for tacklers. Ball carriers were less likely to be injured when they were aware of impending contact (RRR = 0.14 [95% CI, 0.03-0.66]; P = .012) or when they executed a moderate fend (hand-off) (RRR = 0.22 [95% CI, 0.06-0.84]; P = .026). Tacklers were less likely to be injured when performing shoulder tackles (same side as leading leg) in comparison to an arm-only tackle (RRR = 0.02 [95% CI, 0.001-0.79]; P = .037). Ball carriers (RRR = 0.09 [95% CI, 0.01-0.89]; P = .040) and tacklers (RRR = 0.02 [95% CI, 0.001-0.32]; P =.006) were less likely to be injured when initial contact was made with the tackler's shoulder/arm instead of his head/neck.

CONCLUSION

The relative risk of tackle-related injury was higher toward the end of matches. Incorrect technique may contribute to increased injury risk. Implementing recovery strategies between matches, training safe and effective techniques, and improving levels of conditioning may counter the negative effects of fatigue. These findings may assist stakeholders in youth rugby to formulate injury prevention strategies and may improve the preparation of field-side medical staff for managing tackle-related injuries at these or similar tournaments.

NCAA Football Off-Season Training: Unanswered Prayers… A Prayer Answered

Off-season training in year-round collegiate football is purported to be performance enhancing. Absent principles of exercise physiology, excesses in sport-training regimens pose risk to the participant athletes. Since 2000, 33 National Collegiate Athletic Association (NCAA) football players have died in sport: 27 nontraumatic deaths and 6 traumatic deaths, a ratio of 4.5 nontraumatic deaths for every traumatic death. On average, 2 NCAA football players die per season. Best practices, consensus guidelines, and precautions are ignored, elevating the risk. However, standards exist that will, if heeded, prevent nontraumatic death in athletes training for sport. Sickle cell trait status knowledge and tailored precautions are preventing deaths from exertional collapse associated with sickle cell trait. Adherence to established principles of exercise physiology and best-practice training standards, which is long overdue, will help to prevent not only deaths from exertional collapse associated with sickle cell trait but also sudden cardiac, exertional heat stroke, and asthma deaths.

Return to Play after Cervical Spine Injuries: A Consensus of Opinion

Study Design Survey. Objective Sports-related spinal cord injury (SCI) represents a growing proportion of total SCIs but lacks evidence or guidelines to guide clinical decision-making on return to play (RTP). Our objective is to offer the treating physician a consensus analysis of expert opinion regarding RTP that can be incorporated with the unique factors of a case for clinical decision-making. Methods Ten common clinical scenarios involving neurapraxia and stenosis, atlantoaxial injury, subaxial injury, and general cervical spine injury were presented to 25 spine surgeons from level 1 trauma centers for whom spine trauma is a significant component of their practice. We evaluated responses to questions about patient RTP, level of contact, imaging required for a clinical decision, and time to return for each scenario. The chi-square test was used for statistical analysis, with p < 0.05 considered significant. Results Evaluation of the surgeons' responses to these cases showed significant consensus regarding return to high-contact sports in cases of cervical cord neurapraxia without symptoms or stenosis, surgically repaired herniated disks, and nonoperatively healed C1 ring or C2 hangman's fractures. Greater variability was found in recommendations for patients showing persistent clinical symptomatology. Conclusion This survey suggests a consensus among surgeons for allowing patients with relatively normal imaging and resolution of symptoms to return to high-contact activities; however, patients with cervical stenosis or clinical symptoms continue to be a challenge for management. This survey may serve as a basis for future clinical trials and consensus guidelines.

Cervical spine surgery in professional athletes: a systematic review

Cervical surgery is one of the most common surgical spinal procedures performed around the world. The authors performed a systematic review of the literature reporting the outcomes of cervical spine surgery in high-level athletes in order to better understand the nuances of cervical spine pathology in this population.

A search of the MEDLINE database using the search terms “cervical spine” AND “surgery” AND “athletes” yielded 54 abstracts. After exclusion of publications that did not meet the criteria for inclusion, a total of 8 papers reporting the outcome of cervical spine surgery in professional or elite athletes treated for symptoms secondary to cervical spine pathology (focusing in degenerative conditions) remained for analysis. Five of these involved the management of cervical disc herniation, 3 were specifically about traumatic neurapraxia.

The majority of the patients included in this review were American football players. Anterior cervical discectomy and fusion (ACDF) was commonly performed in high-level athletes for the treatment of cervical disc herniation. Most of the studies suggested that return to play is safe for athletes who are asymptomatic after ACDF for cervical radiculopathy due to disc herniation. Surgical treatment may provide a higher rate of return to play for these athletes than nonsurgical treatment. Return to play after cervical spinal cord contusion may be possible in asymptomatic patients. Cervical cord signal changes on MRI may not be an absolute contraindication for return to play in neurologically intact patients, according to some authors. Cervical contusions secondary to cervical stenosis may be associated with a worse outcome and a higher recurrence rate than those those secondary to disc herniation. The evidence is low (Level IV) and individualized treatment must be recommended.

Ultrasound evaluation of foot deformities in infants

Foot deformity in infants is the most common congenital musculoskeletal condition. A precise diagnosis can sometimes be impossible to establish clinically. Radiologic imaging plays a major role in the evaluation of musculoskeletal abnormalities. However conventional imaging techniques, such as plain radiographs of the foot, are of very little help in this age group because of the lack of ossification of the tarsal bones. US presents a significant advantage because it permits the visualization of cartilaginous structures. This leads to the detailed assessment of foot deformities in infants. Furthermore, US can also be used as a dynamic imaging modality. Different scanning views are beneficial to evaluate the complete anatomy of the foot; depending on the suspected clinical diagnosis, some planes are more informative to display the pathological features of a specific deformity. We describe the US findings of five of the most common foot deformities referred to our pediatric orthopedic clinic (clubfoot, simple metatarsus adductus, skewfoot, and oblique and vertical talus). For each deformity we propose a specific imaging protocol based on US to provide an accurate diagnosis. US is a complementary tool to the clinical examination for determining the diagnosis and the severity of the deformity and also for monitoring the efficacy of treatment. Radiologists investigating foot deformities in infants should consider using US for the detailed assessment of the foot in this age group.

The envelope of motion of the cervical spine and its influence on the maximum torque generating capability of the neck muscles

The posture of the head and neck is critical for predicting and assessing the risk of injury during high accelerations, such as those arising during motor accidents or in collision sports. Current knowledge suggests that the head's range-of-motion (ROM) and the torque-generating capability of neck muscles are both dependent and affected by head posture. A deeper understanding of the relationship between head posture, ROM and maximum torque-generating capability of neck muscles may help assess the risk of injury and develop means to reduce such risks. The aim of this study was to use a previously-validated device, known as Neck Flexibility Tester, to quantify the effects of head's posture on the available ROM and torque-generating capability of neck muscles. Ten young asymptomatic volunteers were enrolled in the study. The tri-axial orientation of the subjects' head was controlled via the Neck Flexibility Tester device. The head ROM was measured for each flexed, extended, axially rotated, and laterally bent head's orientation and compared to that in unconstrained neutral posture. Similarly, the torque applied about the three anatomical axes during Isometric Maximum Voluntary Contraction (IMVC) of the neck muscles was measured in six head's postures and compared to that in fully-constrained neutral posture. The further from neutral the neck posture was the larger the decrease in ROM and IMVC. Head extension and combined two-plane rotations postures, such as extension with lateral bending, produced the largest decreases in ROM and IMVC, thus suggesting that these postures pose the highest potential risk for injury.

Significance of T2 Hyperintensity on Magnetic Resonance Imaging After Cervical Cord Injury and Return to Play in Professional Athletes

BACKGROUND:

Cervical cord magnetic resonance imaging (MRI) T2 hyperintensity is used as evidence of cord trauma in the evaluation and management of athletes in contact sports. The long-term pathophysiologic and prognostic value of this finding is poorly understood, especially in return to play (RTP).

OBJECTIVE:

To examine the significance of T2 hyperintensity in the cervical spinal cord of professional athletes.

METHODS:

Retrospective review of MRI T2 hyperintensity findings between 2007 and 2014 in 5 professional athletes. Pertinent examination and demographics, including mechanism of injury, surgical intervention, radiographs, MRI studies, long-term outcomes, and RTP recommendations were collected.

RESULTS:

Four National Football League players and 1 professional wrestler had prior traumatic neurapraxia that at the time of initial consultation had resolved. MRIs showed congenitally small cervical canal (1) and multilevel spondylosis/stenosis/disc herniation (4) along with focal cord T2 hyperintensity (5). The signal abnormalities were at C3/C4 (3), C4 mid-vertebral body (1), and C5/C6 (1). Four athletes had single-level anterior cervical discectomy and fusion, and 1 was nonoperative. Serial MRI imaging at 3 months after surgery showed hyperintensity partially resolved (4) and unchanged (1), and at 9-months 3 of the 5 completely resolved. Based on the author's RTP criteria, 4 of 5 were released to return to their sport. Clearance for RTP preceded complete resolution of MRI T2 hyperintensity in 3 of 4 athletes. The 2 athletes that have returned to profession sport have not had any additional episodes of neurapraxia or any cervical spine-related complications.

CONCLUSION:

MRI T2 hyperintensity in contact sport athletes who are symptom-free with normal examination and no evidence of spinal instability may not be a contraindication to RTP. Additional observations are needed to confirm this observation.

Degenerative changes in adolescent spines: a comparison of motocross racers and age-matched controls

OBJECT

Motocross racing is a popular sport; however, its impact on the growing/developing pediatric spine is unknown. Using a retrospective cohort model, the authors compared the degree of advanced degenerative findings in young motocross racers with findings in age-matched controls.

METHODS

Patients who had been treated for motocross-related injury at the authors' institution between 2000 and 2007 and had been under 18 years of age at the time of injury and had undergone plain radiographic or CT examination of any spinal region were eligible for inclusion. Imaging was reviewed in a blinded fashion by 3 physicians for degenerative findings, including endplate abnormalities, loss of vertebral body height, wedging, and malalignment. Acute pathological segments were excluded. Spine radiographs from age-matched controls were similarly reviewed and the findings were compared.

RESULTS

The motocross cohort consisted of 29 riders (mean age 14.7 years; 82% male); the control cohort consisted of 45 adolescents (mean age 14.3 years; 71% male). In the cervical spine, the motocross cohort had 55 abnormalities in 203 segments (average 1.90 abnormalities/patient) compared with 20 abnormalities in 213 segments in the controls (average 0.65/patient) (p = 0.006, Student t-test). In the thoracic spine, the motocross riders had 51 abnormalities in 292 segments (average 2.04 abnormalities/patient) compared with 25 abnormalities in 299 segments in the controls (average 1.00/patient) (p = 0.045). In the lumbar spine, the motocross cohort had 11 abnormalities in 123 segments (average 0.44 abnormalities/patient) compared with 15 abnormalities in 150 segments in the controls (average 0.50/patient) (p = 0.197).

CONCLUSIONS

Increased degenerative changes in the cervical and thoracic spine were identified in adolescent motocross racers compared with age-matched controls. The long-term consequences of these changes are unknown; however, athletes and parents should be counseled accordingly about participation in motocross activities.

The effect of lateral eccentricity on failure loads, kinematics, and canal occlusions of the cervical spine in axial loading

Current neck injury criteria do not include limits for lateral bending combined with axial compression and this has been observed as a clinically relevant mechanism, particularly for rollover motor vehicle crashes. The primary objectives of this study were to evaluate the effects of lateral eccentricity (the perpendicular distance from the axial force to the centre of the spine) on peak loads, kinematics, and spinal canal occlusions of subaxial cervical spine specimens tested in dynamic axial compression (0.5 m/s). Twelve 3-vertebra human cadaver cervical spine specimens were tested in two groups: low and high eccentricity with initial eccentricities of 1 and 150% of the lateral diameter of the vertebral body. Six-axis loads inferior to the specimen, kinematics of the superior-most vertebra, and spinal canal occlusions were measured. High speed video was collected and acoustic emission (AE) sensors were used to define the time of injury. The effects of eccentricity on peak loads, kinematics, and canal occlusions were evaluated using unpaired Student t-tests. The high eccentricity group had lower peak axial forces (1544 ± 629 vs. 4296 ± 1693 N), inferior displacements (0.2 ± 1.0 vs. 6.6 ± 2.0 mm), and canal occlusions (27 ± 5 vs. 53 ± 15%) and higher peak ipsilateral bending moments (53 ± 17 vs. 3 ± 18 Nm), ipsilateral bending rotations (22 ± 3 vs. 1 ± 2°), and ipsilateral displacements (4.5 ± 1.4 vs. -1.0 ± 1.3 mm, p<0.05 for all comparisons). These results provide new insights to develop prevention, recognition, and treatment strategies for compressive cervical spine injuries with lateral eccentricities.

Disc herniations in the national football league

STUDY DESIGN

Retrospective analysis of a prospectively collected database.

OBJECTIVE

To determine the overall incidence, location, and type of disc herniations in professional football players to target treatment issues and prevention.

SUMMARY OF BACKGROUND DATA

Disc herniations represent a common and debilitating injury to the professional athlete. The NFL's (National Football League's) Sports Injury Monitoring System is a surveillance database created to monitor the league for all injuries, including injuries to the cervical, thoracic, and lumbar spine.

METHODS

A retrospective analysis was performed on all disc herniations to the cervical, thoracic, and lumbar spine during a 12-season period (2000-2012) using the NFL's surveillance database. The primary data points included the location of the injury, player position, activity at time of injury, and playing time lost due to injury.

RESULTS

During the 12 seasons, 275 disc herniations occurred in the spine. In regard to location, 76% occurred in the lumbar spine and most frequently affected the L5-S1 disc. The offensive linemen were most frequently injured. As expected, blocking was the activity that caused most injuries. Lumbar disc herniations rose in prevalence and had a mean loss of playing time of more than half the season (11 games). Thoracic disc herniations led to the largest mean number of days lost overall, whereas players with cervical disc herniations missed the most practices.

CONCLUSION

Disc herniations represent a significant cause of morbidity in the NFL. Although much attention is placed on spinal cord injuries, preventive measures targeting the cervical, thoracic, and lumbar spine may help to reduce the overall incidence of these debilitating injuries.Level of Evidence: N/A.

Catastrophic head and neck injuries in judo players in Japan from 2003 to 2010

BACKGROUND

Few studies have documented catastrophic head and neck injuries in judo, but these injuries deserve greater attention.

PURPOSE

To determine the features of catastrophic head and neck injuries in judo.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

This study was based on the accident reports submitted to the All Japan Judo Federation's System for Compensation for Loss or Damage. A total of 72 judo injuries (30 head, 19 neck, and 23 other injuries) were reported between 2003 and 2010. The investigated parameters were mechanism of injury, age at time of injury, length of judo experience, diagnosis, and outcome.

RESULTS

Among head injuries, 27 of 30 (90%) occurred in players younger than 20 years of age. The relationship between age, mechanism, and location of injury was more relevant when players younger than 20 years incurred head injury while being thrown (P = .0026). Among neck injuries, 13 of 19 (68%) occurred in players with more than 36 months of experience. The relationship between experience, mechanism, and location of injury was more relevant when experienced players incurred neck injury while executing an offensive maneuver (P = .0294). Acute subdural hematoma was diagnosed in 94% of head injuries. The outcomes of head injury were as follows: 15 players died; 5 were in a persistent vegetative state; 6 required assistance because of higher brain dysfunction, hemiplegia, or aphasia; and 4 had full recovery. Among neck injuries, 18 players were diagnosed with cervical spine injury, 11 of whom had fracture-dislocation of the cervical vertebra; there was also 1 case of atlantoaxial subluxation. The outcomes of neck injury were as follows: 7 players had complete paralysis, 7 had incomplete paralysis, and 5 had full recovery.

CONCLUSION

Neck injuries were associated with having more experience and executing offensive maneuvers, whereas head injuries were associated with age younger than 20 years and with being thrown.

Cervical spine injury biomechanics: Applications for under body blast loadings in military environments

BACKGROUND

While cervical spine injury biomechanics reviews in motor vehicle and sports environments are available, there is a paucity of studies in military loadings. This article presents an analysis on the biomechanics and applications of cervical spine injury research with an emphasis on human tolerance for underbody blast loadings in the military.

METHODS

Following a brief review of published military studies on the occurrence and identification of field trauma, postmortem human subject investigations are described using whole body, intact head-neck complex, osteo-ligamentous cervical spine with head, subaxial cervical column, and isolated segments subjected to differing types of dynamic loadings (electrohydraulic and pendulum impact devices, free-fall drops).

FINDINGS

Spine injuries have shown an increasing trend over the years, explosive devices are one of the primary causal agents and trauma is attributed to vertical loads. Injuries, mechanisms and tolerances are discussed under these loads. Probability-based injury risk curves are included based on loading rate, direction and age.

INTERPRETATION

A unique advantage of human cadaver tests is the ability to obtain fundamental data to delineate injury biomechanics and establish human tolerance and injury criteria. Definitions of tolerances of the spine under vertical loads based on injuries have implications in clinical and biomechanical applications. Primary outputs such as forces and moments can be used to derive secondary variables such as the neck injury criterion. Implications are discussed for designing anthropomorphic test devices that may be used to predict injuries in underbody blast environments and improve the safety of military personnel.

Fatalities in high school and college football players

BACKGROUND

Fatalities in football are rare but tragic events.

PURPOSE

The purpose was to describe the causes of fatalities in high school and college football players and potentially provide preventive strategies.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We reviewed the 243 football fatalities reported to the National Center for Catastrophic Sports Injury Research from July 1990 through June 2010.

RESULTS

Football fatalities averaged 12.2 per year, or 1 per 100,000 participants. There were 164 indirect (systemic) fatalities (average, 8.2 annually [or 0.7 per 100,000 participants]) and 79 direct (traumatic) fatalities (average, 4.0 annually [or 0.3 per 100,000 participants]). Indirect fatalities were 2.1 times more common than direct fatalities. The risk of a fatality in college compared with high school football players was 2.8 (95% CI, 0.7-8.2) times higher for all fatalities, 3.6 (95% CI, 2.5-5.3) times higher for indirect events, 1.4 (95% CI, 0.6-3.0) times higher for direct injuries, 3.8 (95% CI, 1.8-8.3) times higher for heat illness, and 66 (95% CI, 14.4-308) times higher for sickle cell trait (SCT) fatalities. Most indirect events occurred in practice sessions; preseason practices and intense conditioning sessions were vulnerable periods for athletes to develop heat illness or SCT fatalities, respectively. In contrast, most brain fatalities occurred during games. The odds of a fatality during the second decade, compared with the first decade of the study, were 9.7 (95% CI, 1.2-75.9) for SCT, 1.5 (95% CI, 0.8-2.9) for heat illness, 1.1 (95% CI, 0.8-1.7) for cardiac fatalities, and 0.7 (95% CI, 0.4-1.2) for brain fatalities. The most common causes of fatalities were cardiac failure (n = 100, 41.2%), brain injury (n = 62, 25.5%), heat illness (n = 38, 15.6%), SCT (n = 11, 4.5%), asthma and commotio cordis (n = 7 each, 2.9% each), embolism/blood clot (n = 5, 2.1%), cervical fracture (n = 4, 1.7%), and intra-abdominal injury, infection, and lightning (n = 3, 1.2% each).

CONCLUSION

High school and college football have approximately 12 fatalities annually with indirect systemic causes being twice as common as direct blunt trauma. The most common causes are cardiac failure, brain injury, and heat illness. The incidence of fatalities is much higher at the college level for most injuries other than brain injuries, which were only slightly more common at the college level. The risk of SCT, heat-related, and cardiac deaths increased during the second decade of the study, indicating these conditions require a greater emphasis on diagnosis, treatment, and prevention.

Outcomes After Anterior Cervical Discectomy and Fusion in Professional Athletes

BACKGROUND:

Significant controversy exists regarding when an athlete may return to contact sports after anterior cervical discectomy and fusion (ACDF). Return-to-play (RTP) recommendations are complicated due to a mix of medical factors, social pressures, and limited outcome data.

OBJECTIVE:

The aim of this study was to characterize our diagnostic and surgical criteria, intervention, postoperative imaging results, and rehabilitation and report RTP decisions and outcomes for professional athletes with cervical spine injuries.

METHODS:

Fifteen professional athletes who had undergone a 1-level ACDF by a single neurosurgeon were identified after a retrospective chart and radiographic review from 2003 to 2012. Patient records and imaging studies were recorded.

RESULTS:

Seven of the 15 athletes presented with neurapraxia, 8 with cervical radiculopathy, and 2 with hyperintensity of the spinal cord. Cervical stenosis with effacement of the cerebrospinal fluid signal was noted in 14 subjects. The operative level included C3-4 (4 patients), C4-5 (1 patient), C5-6 (8 patients), and C6-7 (2 patients). All athletes were cleared for RTP after a neurological examination with normal findings, and radiographic criteria for early fusion were confirmed. Thirteen of the 15 players returned to their sport between 2 and 12 months postoperatively (mean, 6 months), with 8 still participating. The RTP duration of the 5 who retired after full participation ranged from 1 to 3 years. All athletes remain asymptomatic for radicular or myelopathic symptoms or signs.

CONCLUSION:

After a single-level ACDF, an athlete may return to contact sports if there are normal findings on a neurological examination, full range of neck movement, and solid arthrodesis. There may be an increased risk of the development of adjacent segment disease above or below the level of fusion. Cord hyperintensity may not necessarily preclude RTP.

Cervical spinal cord contusion in professional athletes: a case series with implications for return to play

STUDY DESIGN

Retrospective case series.

OBJECTIVE

This report provides long-term follow-up on athletes who have sustained a cervical spinal cord contusion. Their magnetic resonance (MR) image is correlated with clinical signs and symptoms. Mechanism of injury and a hypothesis of etiology are reported.

SUMMARY OF BACKGROUND DATA

Current return-to-play criteria for athletes who sustain a cervical cord contusion are based on expert opinion only. Decision making for this clinical situation in athletes carries significant clinical, legal, and economic ramifications. The natural history, clinical correlation, and effect of surgery for athletic cervical cord contusions have not been established. The mechanism of injury for this entity has historically emphasized axial loading.

METHODS

The case histories, physical examination, and MR images were reviewed for 4 professional athletes. All athletes had documented cervical cord contusions. None of the athletes had an acute disc herniation, fracture, instability, or focal cord compression. All athletes were contacted by telephone to assess symptoms at a minimum follow-up of 2 years after injury.

RESULTS

All 4 athletes had congenital stenosis, defined as lack of CSF signal around the cord on an MR image. All underwent anterior fusions at the level of their contusion. In follow-up, 2 athletes developed new contusions: one more than 5 years later, adjacent to a fusion; and 1, 2 years later, not adjacent to his previous fusion. No athlete developed permanent neurological sequelae. The presence of a contusion did not correlate with athletes' signs and symptoms. The mechanism of injury was hyperextension.

CONCLUSION

It is hypothesized that the horizontal facet orientation of the C3-C4 level, congenital stenosis, and relative hypermobility in extension are the contributing factors in the cause of this clinical entity. An anterior fusion at the C3-C4 level seems to be the most reliable method of preventing or delaying the return of symptoms. Return-to-play guidelines should emphasize the athletes' history of symptoms in context with their MR image because there is poor correlation between the finding of a contusion and the clinical presentation. Recurrence of symptoms is common and the long-term consequences of repeated episodes remain unknown.

Neck injury response to direct head impact

Previous in vivo studies have observed flexion of the upper or upper/middle cervical spine and extension at inferior spinal levels due to direct head impacts. These studies hypothesized that hyperflexion may contribute to injury of the upper or middle cervical spine during real-life head impact. Our objectives were to determine the cervical spine injury response to direct head impact, document injuries, and compare our results with previously reported in vivo data. Our model consisted of a human cadaver neck (n=6) mounted to the torso of a rear impact dummy and carrying a surrogate head. Rearward force was applied to the model's forehead using a cable and pulley system and free-falling mass of 3.6kg followed by 16.7kg. High-speed digital cameras tracked head, vertebral, and pelvic motions. Average peak spinal rotations observed during impact were statistically compared (P<0.05) to physiological ranges obtained from intact flexibility tests. Peak head impact force was 249 and 504N for the 3.6 and 16.7kg free-falling masses, respectively. Occipital condyle loads reached 205.3N posterior shear, 331.4N compression, and 7.4Nm extension moment. We observed significant increases in intervertebral extension peaks above physiologic at C6/7 (26.3° vs. 5.7°) and C7/T1 (29.7° vs. 4.6°) and macroscopic ligamentous and osseous injuries at C6 through T1 due to the 504N impacts. Our results indicate that a rearward head shear force causes complex neck loads of posterior shear, compression, and extension moment sufficient to injure the lower cervical spine. Real-life neck injuries due to motor vehicle crashes, sports impacts, or falls are likely due to combined loads transferred to the neck by direct head impact and torso inertial loads.

Cervical spine injuries and the return to football

Background:

The literature dealing with the diagnosis and treatment of cervical spine injuries is considerable. Absent, however, are comprehensive criteria or guidelines for permitting or prohibiting return to collusion activities such as tackle football.

Objective:

The purpose of this report is to describe developmental and posttraumatic conditions of the cervical spine as presenting (1) no contraindication, (2) relative contraindication, or (3) an absolute contraindication to continued participation in tackle football and other contact activities.

Study Design:

Systematic review.

Methods:

Analysis of data compiled from more than 1200 cervical spine injuries documented by the National Football Head and Neck Registry, in addition to a review of the limited published literature, plus an understanding of the recognized axial load injury mechanism and extensive anecdotal experience.

Conclusion:

The one overriding principle regarding the return to football or, for that matter, any collusion activity is that the individual be asymptomatic, pain-free, and neurologically intact and have full strength and full range of cervical motion.