JOURNAL OF NEUROTRAUMA XX:1–5 (XX, XX, 2014) ª Mary Ann Liebert, Inc. DOI: 10.1089/neu.2013.3253
Helmet Use and Cervical Spine Injury: A Review of Motorcycle, Moped, and Bicycle Accidents at a Level 1 Trauma Center Kristopher G. Hooten and Gregory J. A. Murad
Helmet use in two-wheeled vehicle accidents is widely reported to decrease the rates of death and traumatic brain injury. Previous reports suggest that there exists a trade off with helmet use consisting of an increased risk of cervical spine injuries. Recently, a review of a national trauma database demonstrated the opposite, with reduction in cervical spinal cord injuries in motorcycle crashes (MCC). In 2000, the State of Florida repealed its mandatory helmet law to make helmet use optional for individuals older than 21 with $10,000 of health insurance coverage. To better ascertain the risks of cervical spine injury with non-helmet use in all two-wheeled vehicles, we analyzed the University of Florida level one trauma center experience. We reviewed the Traumatic injury database over a five-year period ( January 1, 2005, to July 1, 2010) for all patients involved in two-wheeled vehicle accidents. Patients were stratified according to vehicle type (motorcycle, scooter, and bicycle), helmet use, and the presence or absence of a cervical spine injury. Outcomes were compared for injury severity, cervical spine injury, cervical spinal cord injury, and presence of cervical spine injuries requiring surgery. Population means were compared using paired t-test. A total of 1331 patients were identified: 995 involved in motorcycle accidents, 87 involved in low-powered scooter accidents, and 249 involved in bicycle accidents. Helmet use was variable between each group. One hundred thirtyfive total cervical spine injuries were identified. No evidence was found to suggest an increased risk of cervical spine injury or increased severity of cervical spine injury with helmet use. This fact, in combination with our previous findings, suggest that the law’s age and insurance exemption should be revoked and a universal helmet law be reinstated in the state of Florida. Key Words: bicycle, cervical spine injury, helmet, Florida, motorcycle, scooter, two-wheeled vehicles
considers the idea that helmets cause neck or spinal cord injuries to be only a common myth; however, a report in 1986 by Goldstein that is often cited by anti-helmet lobbyists argues that motorcyclists face a trade-off between traumatic brain injury (TBI) and cervical spine injury by wearing a helmet.12,13 Recently, a review of the national trauma database by Crompton and colleagues disputes this assertion, arguing that helmets reduce the risk of cervical spine injuries.14 Controversy still exists, however, with a more recent report suggesting that helmets may increase or decrease the risk of cervical spine injury based on crash and direction of impact.15 To better ascertain the risks of cervical spine injury with nonhelmet use in all two-wheeled vehicles, we retrospectively analyzed the University of Florida level one trauma database over a five-year period.
n 2000, the state of Florida repealed its mandatory helmet law. In the decade that followed, helmet use decreased and motorcycle fatalities rapidly increased across the state.1,2 Motorcycle injuries have also increased across the entire United States as well, with the incidence of fatalities nearly doubling since 1997.3 We and numerous other authors previously reported that the use of helmets greatly benefit both riders and society with improved discharge outcomes, a reduction in death rate, a reduction in traumatic brain injury, and a reduction in the cost of hospitalization.1,4–11 Despite the data and the increasing death toll, the state of Florida makes helmet use optional for individuals older than 21 with $10,000 of health insurance coverage. Lobbyists against mandatory helmet laws cite three main arguments: personal freedom, decreased peripheral vision from helmets, and increased risk of cervical spine injury with the use of helmets. The latter argument is based on the theory of increased weight of the helmet results in increased torque and forces applied to the cervical spine. The National Highway Traffic Safety Administration
Methods We reviewed the University of Florida Trauma Registry from January 1, 2005 to June 1, 2010. The University of Florida Trauma Center services twelve northern Florida counties with a total
Department of Neurological Surgery, University of Florida, Gainesville, Florida.
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estimated population of one million people. Records were searched to identify patients from two-wheeled vehicle accidents with published State of Florida paramedic trauma alerts triage criteria or any patient with an International Classification of Diseases, Ninth Revision (ICD-9) code 800–904 who was admitted for 24 h or died in the emergency department. Patients were stratified according to the use of a helmet at time of accident and vehicle type. The Florida definition of low-powered scooters with engines of 50 cc or less was used for distinction. Driver and passengers were not considered separately. Outcomes were compared for baseline population statistics, injury severity score (ISS), presence of cervical spine injury, and presence of cervical spinal cord injury. Patients underwent cervical spine imaging with helical CT or MRI when clinically indicated. Each chart was individually reviewed to confirm ICD-9 screening and each radiographic image evaluated for the presence of cervical spine injury. Images in question underwent a blinded radiographic review by the senior author. ISS was evaluated to determine the equality in the severity of trauma observed in each group with cervical spine injuries. Cervical spine injury was defined as the presence of ligamentous, bone, or spinal cord injury. Spinal cord injury or fractures requiring surgical stabilization were sub-classified as ‘‘severe’’ cervical spine injuries for comparison to determine if there is an increased severity of injury with helmet use.
hospitalization. Helmet status was clearly documented in admission history and physical, emergency medical service notes, and/or discharge summary. One hundred eight patients were excluded because helmet status was not documented. Of the 1331 remaining patients, 995 (74.8%) were involved in motorcycles accidents, 249 (18.7%) were involved in bicycle accidents, and 87 (6.5%) were involved in scooter/moped accidents. The majority of riders were male (1134 /1331). Seven hundred forty-nine riders were nonhelmeted and 582 were helmeted. In the motorcycle group there were 995 patients—522 helmeted and 473 non-helmeted. In the motorcycle subgroup, women were less likely to be wearing a helmet (57/127 [45%] women versus 465/868 [54%] men; p < 0.012). The average age of helmeted riders was significantly lower than that of non-helmeted riders (35.2 vs. 40.8; p < 0.0001). There were 87 total patients involved in low-power cycle accidents. Most riders tended to be non-helmeted (52/62 [84%] of men and 10/ 13 [88%] of women). The average age of the helmeted rider trended higher (43.5 years vs. 38.2 years helmeted and non-helmeted, respectively) but no statistical significance was found. For the population of bicycle riders, there were 249 total patients, 204 male and 45 female. The average age of helmeted riders trended higher (39.1 and 33.9 helmeted vs. non-helmeted riders, respectively) but no statistical significance was seen. This data is summarized in Table 1.
Statistical analysis Statistical methods include chi-squared, paired t-test as appropriate to compare data groups. P values were adjusted by Bonferroni’s method, and values of less than 0.05 were considered significant. Results Patient demographics From January 2005 to June 2010, there were a total of 1439 patients involved in two-wheeled vehicle accidents who arrived as a trauma alert or had a traumatic injury requiring at least a 24-h
Motorcycle Of the 995 motorcycle accidents, there was a total of 105 documented cervical spine injuries. The incidence in the helmeted group was 52/522 (10.0%) versus 53/473 (11.2%) in the nonhelmeted group ( p = 0.53). The ISS of each cervical spine injury group was similar, 21.6 – 1.5 versus 21.2 – 1.8 for the helmeted and non-helmeted groups, respectively ( p = 0.87). Further classification by spinal cord injury and severe cervical spine injuries is summarized in Table 2. There was no statistically significant difference between the helmeted and non-helmeted populations.
Table 1. Patient Demographics All patients Total Male Female Age Motorcycle Male Female Age Discharge to home/rehab Discharge to SNF/death Scooter/moped Male Female Age Discharge to home/rehab Discharge to SNF/death Bicycle Male Female Age Discharge to home/rehab Discharge to SNF/death
n = 1331 n = 1134 n = 197 n = 995 n = 868 n = 127
n = 87 n = 62 n = 45
n = 249 n = 204 n = 45
582 512 (45.2%) 60 (35.5%) 35.72 – 17.58 522 465 (53.6%) 57 (44.9%) 35.2 – 17.28 476 (91.2%) 46 (8.8%) 13 10 (16.13%) 3 (12.0%) 43.46 – 19.58 12 (92.3%) 1 (7.7%) 47 37 (18.14%) 10 (22.22%) 39.11 – 19.73 44 (93.6%) 3 (6.4%)
749 622 (54.9%) 127 (64.7%) 38.71 – 16.93 473 403 (46.4%) 70 (55.1%) 40.8 – 14.36 396 (83.7%) 77 (16.3%) 74 52 (83.87%) 10 (88.0%) 38.22 – 21.01 68 (91.9%) 6 (8.1%) 202 167 (81.86%) 35 (77.88%) 33.91 – 19.70 177 (87.6%) 25 (12.4%)
SNF, skilled nursing facility; CI, confidence interval.
Women less likely wearing helmet p50.012 Average age of helmeted riders lower p50.0017 Women significantly less likely wearing helmet p 0.05 Age of helmeted trended to be older p = 0.314 Odds ratio = 1.850; 95% CI = [0.714, 4.795]; p = 0.21 Odds of death: 2.165; 95% CI = [0.479, 9.787]; p = 0.316
HELMET USE AND CERVICAL SPINE INJURY
Table 2. Motorcycle Patients Sustaining Cervical Spine Injuries Helmeted Total patients (n = 995) Cervical spine injury Age of cervical spine injuries Male Female ISS of cervical spine injuries Spinal cord injury (n = 14) Surgical fractures (n = 19) Severe injuries (n = 21)
Table 4. Bicycle Patients Sustaining Cervical Spine Injuries
Non-helmeted p values
522 52 (10.0%) 45.5 – 16.0
473 53 (11.2%) 43.6 – 12.7
45 (86.5%) 7 (13.5%) 21.6 – 1.5
46 (86.6%) 7 (13.4%) 21.2 – 1.8
p = 0.869
7 (1.4%) 10 (1.9%) 11 (2.1%)
7 (1.5%) 9 (1.9%) 10 (2.1%)
p = 0.931 p = 0.994 p = 0.989
p = 0.532 p = 0.804 p = 0.442
ISS, injury severity score.
Helmeted Non-helmeted p values Total patients (n = 249) Cervical spine injury (n = 22) Age of cervical spine injuries Male Female ISS of cervical spine injuries Spinal cord injury (n = 5) Surgical fractures (n = 6) Severe injuries (n = 6)
47 3 (6.5%) 38.3 – 4.5
202 19 (9.4%) 38.0 – 21.1
p = 0.739 p = 0.702
3 (100%) 0 28.3 – 9.4
19 (100%) 0 23.2 – 3.8
p = 0.632
2 (4.3%) 2 (4.3%) 2 (4.3%)
3 (1.5%) 4 (2.1%) 4 (2.1%)
p = 0.319 p = 0.330 p = 0.330
ISS, injury severity score.
Moped/low-power scooter Of the 87 low-powered scooter accidents recorded, there were eight total cervical spine injuries. The incidence of cervical spine injury in the helmeted group was 1/14 (7.1%) versus 7/73 (9.7%) for the non-helmeted group ( p = 1). The ISS of the cervical spine injury population was 45.0 (n = 1) versus 23.4 – 4.3 for helmeted and nonhelmeted, respectively ( p = 0.19). There was only one patient in the helmeted population and two patients in the non-helmeted that sustained cervical spine fractures with an underlying spinal cord injury. There was no statistically significant difference between the helmeted and non-helmeted populations. Results are summarized in Table 3. Bicycle Of the 249 bicycle accidents, there were 22 cervical spine injuries reported. The incidence of cervical spine injury in the helmeted group was 3/47 (6.5%) versus 19/202 (9.4%) for the non-helmeted group ( p = 0.74). The ISS of the cervical spine injury population was 28.3 – 9.4 (n = 3) versus 23.2 – 3.8 for helmeted and nonhelmeted riders, respectively ( p = 0.63). Further classification by spinal cord injury, surgical fractures, and severe cervical spine injuries is summarized in Table 4. Again, there was no statistically significant difference between the helmeted and non-helmeted populations. Discussion Despite an overwhelming amount of evidence that supports the use of helmets in injury prevention, the Florida legislature repealed Table 3. Scooter/Moped Patients Sustaining Cervical Spine Injuries
Total patients (n = 87) Cervical spine injury Age of cervical spine injuries Male Female ISS of cervical spine injuries Spinal cord injury (n = 3) Surgical fractures (n = 3) Severe injuries (n = 3) ISS, injury severity score.
14 1 (7.1%) 55 (n = 1)
73 7 (9.7%) 45.6 – 14.7
p=1 p = 0.750
1 (100%) 0 45 (n = 1)
7 (100%) 0 23.4 – 4.3
p = 0.188
1 (7.1%) 1 (7.1%) 1 (7.1%)
2 (2.8%) 2 (2.8%) 2 (2.8%)
p = 0.392 p = 0.392 p = 0.392
its universal helmet law in 2000. In a state where a seatbelt law is strictly enforced, a helmet law is not. Opponents against mandatory helmet laws cite three main points including: 1) personal freedom, 2) decreased peripheral vision/increased accidents, and 3) increased risk of cervical spine injury. Riders’ ‘‘personal freedoms’’ have come at a great cost to society. Many authors have previously reported an increased hospitalization cost and lower percentage of health insurance in the non-helmeted population.1,16–23 The argument of increased accident crash risk from vision disturbance has no scientific backing. The absence of helmet use has been cited as a risk factor for accident involvement.24 Also, in multiple studies evaluating peripheral vision, helmets were not found to affect vision or increase reaction time to peripheral stimuli.25,26 For this study, our primary aim was to address the third argument and controversial claim in motorcycles that helmets increase risk of cervical spine injury because of added weight to the head. Previous research, although sparse, suggested that helmet use increases the risk cervical spine injury.12 In 2005, a study from Australia evaluating a series of 110 motorcyclists suggested no difference existed in the odds of cervical spine injury between helmeted and nonhelmeted riders.27 A similar study in Taiwan found no difference in the occurrence of cervical spinal cord injury in motorcyclist.28 A review of the national trauma database by Crompton and colleagues demonstrated a statistically lower proportion of cervical spine injury— 3.5% versus 4.4% for helmeted versus non-helmeted riders.14 More recently, a study from Malaysia suggests helmets may increase cervical spine injury depending on type of impact or crash.15 Dao and colleagues demonstrated that states with mandatory helmet laws had a lower incidence of cervical spine injuries in patients admitted after two-wheeled vehicle accidents, an indirect measure of cervical spine injury and helmet use.29 Our findings demonstrate no difference between the populations. Our study was unique by designing classification based on clinically relevant categories as opposed to ICD-9 diagnoses. We compliment Crompton and colleagues, as theirs was the first study to suggest helmets may play a protective role in cervical spine injury14; however, it was based on ICD-9 coding, which has inherent flaws. ICD-9 coding is limited in the diagnosis codes available for disease classification. As a result of the ICD-9 classification, fracture types were separated into open versus closed vertebral column fracture and open and closed spinal cord injuries. In our review, we found no ‘‘open’’ cervical spine fractures or ‘‘open’’ spinal cord injuries in our population. In addition, ICD-9 coding is typically performed by medical coders with limited
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understanding of clinical diseases, which creates an opportunity for inaccurate coding. By limiting our population to one trauma database, our population was much smaller, thus losing the ability to demonstrate statistical significance between helmeted and nonhelmeted patients. However, we believe we created a greater validity with a thorough chart and radiographic imaging review of each patient, ensuring accurate diagnosis and classification of injuries. By classifying the fractures for clinical relevance, we were further able to demonstrate no difference in the clinical severity of injury between helmet and non-helmet users, contrary to previous common belief. An additional difference in our study was our incidence of cervical spine injury. Our population sustained a cervical spine injury incidence three times higher than reported in the review of the national trauma database. It is well known that with higher degrees of trauma, spinal injuries are more common. The majority of our trauma population is associated with high-speed interstate travel, which likely explains the higher incidence seen. When comparing our populations with cervical spine injuries, the groups were found to be similar in the degree of trauma as calculated by the ISS. This finding supports that the two groups were similar in the degree of trauma seen that resulted in the cervical spine injury. Our second aim was to evaluate helmet use and cervical spine injury in low-powered scooters and bicycles. These helmets are physically different in structure, and the literature is lacking in this area. Most studies for low-powered scooters and bicycles favor helmet use for head injury protection but little is known regarding cervical spine injury risks.30–36 In our populations of moped and lower powered scooter and bicycle riders, we found no difference in the incidence of cervical spine injury but acknowledge the populations are too small to demonstrate statistical significance. In our study, we demonstrate that the prior belief of increased severity of cervical spine injury is false. It is clear that helmets prevent primary injury for head injuries. Limitations include the retrospective nature of the study. In addition, our population does not include the riders who died on scene, which we suspect includes a larger percentage of non-helmeted riders. Helmets’ protection of the cervical spine seen in reviews of the national trauma database though was not identified.14 When writing new legislation, it should be understood that no justification exists for not adopting a mandatory helmet law in a state where seatbelts are enforced in fourwheeled vehicles. Conclusion Our previous findings suggest that the law’s age and insurance exemption should be revoked and a universal helmet be reinstated in the state of Florida. In the argument regarding cervical spine injury, no evidence was found supporting an increased severity of cervical spine injury with helmet use. We hope this study serves as a basis to change legislation in the state of Florida, as well as nationally. Author Disclosure Statement No competing financial interests exist. References 1. Hooten, K.G. and Murad, G.J. (2012). Helmeted vs nonhelmeted: a retrospective review of outcomes from 2-wheeled vehicle accidents at a level 1 trauma center. Clin. Neurosurg. 59, 126–130. 2. Motorcycle Crashes, Fatalities, and Injuries in Florida. (2012). Available at: www.ridesmartflorida.com/dataandstatistics.shtm. Accessed May 5, 2014.
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Address correspondence to: Kristopher G. Hooten, MD Department of Neurological Surgery University of Florida Box 100265 Gainesville, FL 32610-0261 E-mail: [email protected]