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Rehabilitation Medicine, Cornell University, New York, NY, USADepartment of Physical Medicine and Rehabilitation, Hospital for Special Surgery, New York, NY
Rehabilitation Medicine, Cornell University, New York, NY, USADepartment of Physical Medicine and Rehabilitation, Hospital for Special Surgery, New York, NY
Simotas AC, Shen T. Neck pain in demolition derby drivers.
Objective
To investigate neck pain in demolition derby car drivers. Arch Phys Med Rehabil 2005;86:693–6.
Design
Retrospective survey.
Setting
Internet administered.
Participants
Demolition derby drivers who visited the Web site of the International Demolition Derby Association.
Interventions
Not applicable.
Main outcome measure
Demolition derby neck pain questionnaire.
Results
Forty drivers participated in a mean of 30 career events and had an average of 52 car collisions per event, 55% being rear-end. Mean and maximum collision speeds were 26 and 45 miles/h (41.6km/h, 72km/h), respectively. Only 2 drivers reported their worst postparticipation neck pain lasted more than 3 months, and for 1 it lasted more than a year; for the majority, the worst neck pain event lasted less than 21 days. Three participants reported having mild chronic persistent derby-related neck pain (never went away). The remaining 37 drivers reported no chronic neck pain. The average pain episode was moderate or severe for 8, but for all respondents, the average pain episodes lasted less than 21 days. Ten reported chronic neck pain they believed was unrelated to derby competition (7 mild, 2 moderate, 1 severe).
Conclusions
These data suggest that derby drivers sustain less chronic neck pain after multiple car collision events than might otherwise be expected. Further study of this unique population of car drivers may contribute to understanding whiplash disorder.
PAIN AND MANY ASSOCIATED symptoms occurring around neck, head, and upper extremities after motor vehicle collision (MVC) trauma have been largely referred to as “whiplash.” Whiplash is the most commonly reported injury after MVCs.
Controversy enshrouds every aspect of this term or disorder and what it actually represents. Reasonable agreement exists regarding the biomechanics of the event: it is an acceleration-deceleration mechanism of energy transfer to the cervical spine. Investigators have hypothesized that injury potential is the greatest during the S-shaped phase when there is a simultaneous hyperextension of the lower cervical spine and flexion of the upper cervical spine.
Biologic or structural tissue injury that results from MVCs may include muscle and ligament tears. Fractures to the cervical spine are rare in uncomplicated whiplash.
An injection-based postmortem study of car crash victims who died of head injuries and had normal cervical radiographs detected the presence of disk (rim lesions) and facet joint lesions.
However, the diagnosis relies on the fluoroscopically guided diagnostic analgesic blockade and cannot be diagnosed by medical imaging.
The greatest controversy concerns the explanation for the high rate of chronic neck pain and the extent of disability that occurs with whiplash. The natural history of neck pain generally suggests that most patients should recover over time.
However, a significant number of whiplash patients complain of persistent symptoms despite having a normal physical examination and negative radiographs. In patients who have reported whiplash injuries, between 14% and 40% of patients may develop chronic complaints that persist for years and result in disability, and 10% will have chronic severe pain.
Chronic whiplash syndrome results in a significant burden on society because of time lost from work and insurance litigation. It has been estimated that the total cost to society in the United States may be as high as $3.9 billion.
of car collisions in Lithuania and Greece revealed that chronic neck pain after car collisions occurs dramatically less in these countries where there are fewer litigation costs and, therefore, less potential for secondary gain. Additionally, reports of chronic neck pain or headache are infrequent in participants of recreational activity in which acute neck strains would appear to be common. For instance, fairground bumper car passengers frequently experience rear-end collisions and cervical hyperextension yet rarely report chronic neck pain.
Demolition derby participants would theoretically have an increased risk for developing chronic neck pain. In this sport, contestants drive about an arena of multiple car drivers in free, unregulated patterns. Their objective is to disable all their competitors by repetitively crashing into one another. All types of collisions are permitted except driver’s door collisions. There are no speed limits. Participants usually drive stock sedan or station wagon cars built in the 1970s or 1980s, which are not equipped with airbags. All participants must wear helmets, seat beats, and goggles but no other special protective gear. Drivers must sign an injury waiver form before participation, which states that the individual will assume all legal liability for his/her own safety and will accept the dangers involved in the events.
We retrospectively investigated the occurrence of acute and chronic neck pain in demolition derby participants in relation to the extent of car collision trauma they had experienced. Our hypothesis was that if car collisions result in whiplash injury, derby drivers who undergo many car collisions as a part of their sport would experience a high amount of neck pain at a rate and severity proportional to their exposure to collisions. To accomplish this, we created a questionnaire that would tally the number and speeds of collisions they had incurred during their careers as well as characterize their experience of neck pain events.
Methods
The International Demolition Derby Association (IDDA) maintains a Web site providing information about demolition derbies and claims to have 4000 members. A request was placed on its monthly electronic newsletter asking derby participants, with or without any experience of neck pain, to contact us by e-mail if they were willing to complete a neck pain questionnaire. Those who responded favorably were e-mailed a survey.
The neck pain questionnaire was adapted from the Quebec Task Force initial visit form.
Standard demographic information was obtained. Seventeen questions about the extent and nature of demolition derby activity were created. These were modified after 2 test run trials of the questionnaire with 10 participants. Participants were asked to estimate the number of events in which they had participated in the past 3 years and in their lifetime, the average number of collisions they experienced in 1 derby event, and the percentage that were rear-end in nature. They were also asked to estimate the average and greatest collision speeds at impact (with collision speed referring to the sum of the speeds of both vehicles involved in the collision). Other questions asked about physician visits; fractures sustained; loss of consciousness; and the use of protective gear, specifically neck roll, headrest, and seat belt.
Then participants were asked to rate the intensity and duration of postparticipation neck pain symptoms they experienced on the average, in the worst case, and if they had suffered with any chronic residual (never went away) symptoms in 3 separate sections. Each of 7 symptom categories was rated separately for average, worst, and chronic, and included the following: 1, neck and shoulder pain; 2, reduced or painful neck movements; 3, headache; 4, numbness or tingling in arm or hand; 5, pain in arm and hand, memory problems; 6, problems concentrating; and 7, vision problems. Adjacent to each symptom category were 2 columns: 1 for intensity and 1 for duration. Intensity was rated as 0, none; 1, mild; 2, moderate; 3, severe; and 4, very severe. Duration was 0, none; 1, less than 21 days; 2, between 22 days and 3 months; 3, between 3 months and 1 year; and 4, greater than 1 year. Participants were also asked about neck pain history before becoming involved with the demolition derby sport and whether they had experienced chronic neck pain not attributed to derby participation. Multivariate analysis was performed using the Mann-Whitney U test for ranked data and Spearman rank correlation tests.
Results
Of the 124 surveys sent out, 50 were returned. Of these 50, 40 were completed, for a 30% response rate. Ten of the 50 participants left significant portions of the pain-related questions incomplete. Of the 40 who completed the entire survey, 34 were men and 6 were women (table 1). The average age was 28 years (range, 18–45y). Eighty-two percent of the respondents had at least a high school diploma, and 12.5% were university graduates. Sixty-eight percent were employed full time. These drivers reported participating in an average of 11 events during the past 3 years and an average of 33 events in their total careers. Eighty-four percent of the respondents wore seat belts all the time, 8% most of the time, and 8% sometimes. Thirty of the respondents (75%) reported that they never wear neck-protective gear. Twenty-seven had adjustable head rests, 8 fixed, and 5 no head rests at all in their vehicles. They reported an average of 52 collisions per event. The average estimate for rear-end collisions was 55%. Mean speed for average was 26 miles/h (41.6km/h), and mean speeds for maximum collisions were 45 miles/h (72km/h). The total lifetime collisions (average collision per event × total career events) were an average of 1632 collisions.
Table 1Neck Pain in 40 Derby Drivers: Selected Responses
Variable
Response
Male/female
34/6
Avg age (range), y
28 (16–45)
Avg no. of lifetime events
33
Avg collisions per event
52
% rear-end
53
Avg collision speed (mph)
26
Max collision speed (mph)
44
No. of drivers with LOC episode
5
Avg neck pain after events, n (%)
None
6 (15)
Mild
26 (65)
Moderate
5 (12)
Severe
3 (8)
Duration of avg neck pain, n (%)
None
7 (18)
<3wk
33 (82)
Worst neck pain after events, n (%)
None
9 (22)
Mild
18 (55)
Moderate
5 (12)
Severe
6 (15)
Very severe
2 (5)
Duration of worst neck pain events, n (%)
None
9 (22)
<3wk
27 (67)
3wk–3mo
1 (2)
3–6mo
2 (5)
>6mo
1 (2)
Chronic persistent derby neck pain, n (%)
None
37 (92)
Mild
3 (8)
Chronic nonderby neck pain, n (%)
None
30 (75)
Mild
7 (18)
Moderate
2 (5)
Severe
1 (2)
Abbreviations: Avg, average; LOC, loss of consciousness; Max, maximum.
Only 3 drivers reported ever losing consciousness, and of these only 1 driver reported more than 1 episode. Seven reported sustaining injuries while participating in demolition derbies requiring a physician’s evaluation, although only 2 reported visits to a physician about neck pain. Six patients reported having broken bones but no neck fractures.
Twenty-six drivers reported that, on the average, they had mild neck pain, 5 had moderate, 3 severe, and 6 no pain (fig 1). Furthermore, all respondents believed that an average pain event lasted less than 3 weeks. As their worst-ever experience, 18 drivers reported mild, 5 moderate, 6 severe, and 2 very severe neck pain. Thirty-six drivers reported that their worst neck pain lasted less than 3 weeks, 1 driver reported that his worst neck pain lasted up to 3 months, 2 drivers reported that their worst neck pain lasted 1 year, and 1 driver reported that his worst neck pain lasted more than 1 year (fig 2). Thirty-seven reported no arm pain, 1 reported mild arm pain, and 2 reported moderate arm pain on the average. On the average, arm pain for these 3 drivers lasted less than 3 weeks. As their worst-ever experience, 3 drivers reported mild arm pain and 3 reported moderate arm pain. The remaining 34 drivers reported no arm pain even in the worst case. Five of these 6 drivers reported that their worst arm pain lasted less than 3 weeks, and 1 driver reported that his worst arm pain lasted less than 3 months.
Fig 1Number of drivers reporting neck pain they experienced on the average after events by duration and intensity. Abbreviations: mod, moderate; sev, severe.
Three drivers reported having mild chronic persistent neck pain (never went away) as a result of derby participation, but the remaining 37 respondents reported no chronic neck pain. Ten drivers reported having chronic neck pain unrelated to derby driving. Of these 10 drivers with chronic nonderby neck pain, 7 reported mild, 2 moderate, and 1 severe chronic neck pain. Similarly, 21 drivers reported having had some neck and shoulder pain before they began participating in demolition derby events at all. Of these 21, 19 had experienced pain occasionally or sometimes and only 2 often or almost always. Ten drivers had been subject to a nonderby MVC in which they had a neck injury of some sort. No significant correlation was noted between neck pain and any demographic variables. Similarly, no significant correlation was noted between neck pain and variables of collision trauma exposure, including lifetime events, average collisions per event, rear-end collisions, collision speeds, or use of driver restraints.
None of the demolition derby drivers reported experiencing chronic persistent headache, memory problems, problems concentrating, or visual disturbances. However, 3 drivers reported having had a loss-of-consciousness event, which indicated that a mild traumatic brain injury did occur. On the average, 12 drivers had some postparticipation headache. Eight of the drivers had mild, 3 moderate, and 1 severe headache. All these drivers reported that headaches lasted less than 3 weeks, even for the worst headache event. There was no correlation between headache and neck pain. Interestingly, before any derby exposure, 69% had headache sometimes, 29% never, and 2% often.
Discussion
To our knowledge, this is the first reported investigation of the occurrence of neck pain and associated symptoms in demolition derby drivers. We are not aware of any data on the extent of career sport-related car collision trauma that derbyists undergo, but our limited survey suggests that they willingly subject themselves to a considerable amount of car collision trauma. They report having undergone a median of 1632 lifetime collisions, 55% of which were rear-end, under otherwise normal driver conditions (seat belted and rarely using neck protective restraints).
The majority of participants reported some postevent symptoms. However, on the average, neck pain always lasted less than 3 weeks and was mild or absent for most drivers. Even worst-event neck pain lasted more than 3 weeks for only 10% of the drivers. Arm pain was rarely reported (only 15% even in the worst-case event). Despite 1632 collisions, only 8% had mild chronic neck pain, and the remainder had no chronic neck pain.
The ultimate goal of our study was to compare the derby drivers’ experience of neck pain after car collisions and the occurrence of neck pain after car collisions by drivers in the general population. Neck pain with or without other symptoms occurring after an MVC was the defining criteria for numerous studies available reporting the outcomes of what is generally referred to as whiplash. On the whole, these studies used no other specific clinical criteria to identify whiplash patients, and there is no evidence, thus far, of what identifies a more specific whiplash injury.
Furthermore, no matter what the initial structural injury, it would be unlikely for derby drivers to avoid such an injury after 1632 collisions. The most impressive contrast is that a reasonable review of the whiplash literature suggests that 10% of whiplash victims develop chronic severe pain after only 1 index accident.
Making such comparisons is therefore compelling but is done with a reserve that is hitherto explained.
There were various sources of potential error in this study. Our response rate for returning a mailed out questionnaire was only 30% and this could have created a response bias. A selection bias was already introduced when subjects were solicited by posting an announcement on the IDDA Web site bulletin board asking for volunteers. We have no way of knowing how many eligible IDDA active drivers actually saw and read this announcement. This was an obvious limitation of the study. The data are retrospective and therefore subject to memory error. Some braggart respondents may have exaggerated the extent of their participation and other collision-related data. A retrospective design may also increase the possibility of natural selection or survivorship bias, by which process it is possible that only drivers who do not experience neck pain continue to participate in the sport. The drivers who continue to suffer with pain and injuries drop out.
Aside from these more obvious design flaws are the less obvious but arguable problems of comparing derby driver collisions with whiplash injuries on the whole. The drivers are expectant of possible impact and therefore presumably more guarded and braced for most collisions. Subtle positioning changes may help them prevent injury. They may even have developed adaptive skills that are trained to lessen injury. On the whole, we believe this may be true, but it is unlikely that drivers could be prepared for impact in 100% of their collisions; hence, at least occasionally, they are caught off guard.
The subjective pain experience of these demolition derby participants is not altogether surprising. Biomechanic studies of the whiplash type of distortions that occur during car collisions suggest a mechanism of strain and injury, which normally resolves within a short period of time. Rarely, more protracted neck and arm pain may suggest a more serious structural injury. This pattern of symptom reporting is also in keeping with the fact that objective magnetic resonance imaging findings are rarely present after common whiplash. Chronic neck pain is also rarely reported in other contact sports in which significant cervical spine whiplash-type trauma may occur. Consider unforeseen high-velocity body collisions that may occur in American football, hockey, or soccer. Often other axial loading or distraction forces are at work to cause even greater potential harm.
Motivational differences between derby drivers and people sustaining whiplash injuries in the general population may account for outcome differences. Derby drivers willingly participate in their sport and expect a certain amount of trauma. The possibility for financial gain through litigation is unlikely, and such measures would surely lead to the end of their participation in the sport. They are therefore less likely to succumb to perceptions of victimhood or illness behavior and symptom magnification, which prolong recovery. At the present time, no additional motor vehicle insurance is required for demolition derby participation. The sport’s members proclaim the sports’ relative safety. These factors may contribute to a possible underreporting of injuries.
Drivers may also be reluctant to blame their derby sport for some of their chronic neck pain. Twenty-five percent of the drivers (10/40) claimed to experience some chronic neck pain that they believed was unrelated to the derby competitions. Indeed, 3 of the 40 drivers had moderate to severe chronic nonderby neck pain. Although these numbers are somewhat comparable to prevalence rates of neck pain in the general population, they seem to be at the higher end of the range reported.
Our limited survey of demolition derby drivers suggests that, despite many car collisions, they suffer from relatively little injury to the cervical spine and significantly less chronic pain than might be expected. The data seem to differ with available data on the reported incidence of neck pain that occurs after MVCs in the general population. We were surprised that no other study has been conducted of this unique population of car drivers. This pilot study suggests that further study of greater scientific power is warranted and may contribute greatly to the understanding of the pathophysiology of whiplash trauma and neck pain.
References
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The association between neck pain intensity, physical functioning, depressive symptomatology and time-to-claim-closure after whiplash.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.
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