Non-whiplash soft tissue injuries following low-velocity impact collisions: A retrospective analysis

Introduction

Official figures report a total of 181,384 road traffic accidents (RTAs) and 1792 fatalities in the United Kingdom in 2016. ¹ Of these, 109,046 casualties were car occupants, and it is felt that these figures may be an under-estimate of the severity of the problem. Most of these accidents go through a medico-legal claim process set off by the insurance company which results in award of a compensation to the injured party. Under current rules, all medico-legal claimants need a medico-legal report to assess the type and severity of the injury before compensation can be offered.

Whiplash injuries are disproportionately represented in medico-legal practice and comprise 85% of all RTA claims in the United Kingdom. ² A whiplash injury can be defined as bony or soft tissue injuries of the neck or upper back caused by a flexion or extension of the neck. These injuries typically involve front, rear or side-on impact injuries in which accelerative and decelerative forces impact the head and neck, causing them to be thrown back and forth. Of note, rear end collisions are reported as the most frequent cause. ³

Whilst the majority of patients with whiplash injury recover in a few weeks, it can be associated with a concomitant injury to the shoulder and can also develop into a chronic syndrome with significant impact upon the individual involved. ⁴ This has been associated with somatic, psychological and behavioural factors such as anxiety, sleep disturbance and time away from work. The development of whiplash injury into a chronic whiplash syndrome, where symptoms persist for more than six months, has a well-documented preponderance among females in the 20–40 age range. ³ Settlement of insurance claims does not appear to improve the prognosis, in contrast with an acute whiplash injury.

Despite an increasing body of literature on injuries sustained from seatbelts and airbags, associated psychological disorders and the appropriate management of these, there is relatively little documented upon soft tissue injuries, other than whiplash, in low-velocity motor vehicle collisions.^4,5 With changes to the regulation of the industry and the current requirement for mandatory medico-legal reporting in insurance claims, an increase in medico-legal reporting and regulation of the industry, it is both timely and appropriate to formally document these soft tissue injuries and associations within these. ⁶

Methods

We retrospectively reviewed medico-legal reports prepared between September 2011 and February 2018 of claimants attending the medico-legal practice of a consultant orthopaedic surgeon (HK) in the United Kingdom. The details collected included patient demographics, mechanism of injury, damage to the vehicle, injuries sustained, pre-existing injuries/pathologies and medical attendances following the collision.

Subjects were included in the review if they suffered a soft tissue injury following the collision when travelling in a passenger vehicle that collided with another motor vehicle at low-velocity impact.

Results

There were 2043 medico-legal reports prepared during this period. Of these, 609 met the criteria for inclusion.

There were 232 men and 377 (62%) women. Assuming that there are an equal number of men and women drivers, this difference was statistically significant (binomial distribution test; p < 0.0001). The mean age was 43 years. There was no statistically significant difference in the mean age between men (44 years) and women (43 years) (t-test; p = 0.36). There was no statistically significant difference in age distribution between men and women (chi-squared test; p = 0.9). For both sexes, most of the injuries occurred in those between 20 and 60 years of age, accounting for in the region of 80% of the injured cohort.

Most claimants were drivers (75.5%) followed by front seat (19%) and then rear seat passengers (5.5%). Most claimants were injured following a rear end collision (60%) (Table 1).

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Table 1.

Pattern of impact in relation to the position of the injured party.

	Front collision	Rear collision	Side collision
Driver	49 (11%)	279 (61%)	129 (28%)
Passenger	15 (13%)	68 (59%)	33 (28%)
Rear passenger	5 (15%)	19 (58%)	9 (27%)
Total	69	366	171

With regard to side impact injuries, the side of the impact did not appear to influence whether injuries sustained were ipsilateral or contralateral to the side of impact or bilateral (chi squared test; p = 0.4), as per Table 2.

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Table 2.

Side of impact in relation to side of injury.

Car impact side of individual	Injury ipsilateral side of impact	Injury contralateral side of impact	Bilateral injury
Ipsilateral	38	34	15
Contralateral	24	22	17

Five hundred and thirty-five claimants (88%) reported neck pain. Only 55 patients (9.7%) reported neck pain with no other co-existing injuries. Four hundred and eighty patients (90.3%) reported an injury to at least one other anatomical area. Statistical analysis was further carried out on subgroups depending on anatomical areas injured other than neck.

Shoulder

Two hundred and ninety-two patients (48%) reported shoulder injuries. Of these, 52 patients (18%) complained of bilateral shoulder symptoms. Shoulder injuries were not more common with side impact compared to rear shunt impacts, 83 vs. 171 (Fisher’s exact test; p = 0.3).

With side-on impacts, 31 shoulder injuries were on the same side and 32 injuries on the opposite side of impact (Table 3). Hence, there is no correlation between side of injury and position in the car (chi-squared test combining rear and passenger numbers to comply with chi-squared assumptions, p = 0.99).

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Table 3.

Relationship of shoulder injuries to side of impact.

Injury side compared to collision side	Driver	Passenger	Rear
Contralateral	22	9	1
Ipsilateral	21	9	1

There was no significant difference in age between those with shoulder injuries (42 years) and those without (43 years) (t-test; p = 0.15).

Thoracic or lumbar spine injuries

There was a significant difference in the age of patients with thoracic or lumbar spine injuries (ANOVA; p < 0.0001). Patients with both thoracic and lumbar soft tissue injuries tended to be the youngest. This was followed by those with isolated thoracic injuries, isolated lumbar injuries and then those with neither injury. This last cohort had a mean age nearly 10 years older than individuals who reported both thoracic and lumber injuries as shown in Table 4.

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Table 4.

Thoracic and lumbar soft tissue injuries.

	Thoracic and lumbar	Thoracic	Lumbar	No thoracic or lumbar injury
Number	53	44	289	221
Mean age	37.7	41.2	42.2	46.1

Occupational status

Four hundred and forty-eight (74%) claimants held full time or part time employment, 92 (15%) did not have employment and 68 (11%) were retired (Table 5). Those who were unemployed did not have a greater incidence of injury compared to those in employment (t-test; p = 0.98). Occupational status did not appear to influence the pattern of injuries as well (t-test; p = 0.06).

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Table 5.

Occupational status and pattern of injury.

	Spine (%)	Upper limb (%)	Trunk (%)	Lower limb (%)
Employed	725 (59)	294 (24)	88 (7)	119 (10)
Unemployed	146 (58)	55 (22)	15 (6)	34 (14)
Retired	99 (51)	47 (24)	17 (9)	32 (16)

Psychological symptoms

With limited information on psychological symptoms from our orthopaedic medico-legal report, we subdivided them into two groups: One with anxiety (driving anxiety, being over cautious such as checking mirrors) or those with multiple psychological symptoms. The prevalence of psychological symptoms (both groups combined) among claimants was 53%. This figure was over 10 times the prevalence in the general population of 5%. ⁷ The difference was statistically significant (binomial distribution test; p < 0.0001). Both anxiety and multiple psychological symptoms were associated with a greater number of body parts injured (binomial distribution test; anxiety p < 0.01 and multiple psychological symptoms p < 0.01).

There was no statistically significant difference in age between those with anxiety and those without (t-test; p = 0.8) nor those with other psychological symptoms and those without (t-test; p = 0.2). There was no difference between drivers and passengers with regard to prevalence of anxiety or psychological symptoms (Fisher’s exact test; p = 0.2 and p = 0.7, respectively).

Anxiety was significantly more common in women than men; with 58.8% women and 44.3% of men (Fisher’s exact test; p = 0.0006). However, other psychological symptoms showed no specific association with any gender. In addition, 36.7% of women reported psychological disturbances other than anxiety and 35.3% of men (Fisher’s exact test; p = 0.8). Using logistic regression to identify patient factors independently associated with anxiety, adjustment was made for age, gender, position in car (driver vs. non-driver), employment status (unemployed vs. employed/retired) (Table 6). Gender was the only factor found to be independently linked to anxiety. The adjusted odds for anxiety was 1.85 (95% CI = 1.3–2.6) for females compared to males. Neither age, driver status nor employment status had an association with reporting of anxiety symptoms.

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Table 6.

Logistic Regression of associations of anxiety with gender, age, driver vs. passenger and unemployed vs. employed/retired.

	Odds ratio	95% confidence interval	p
Female vs. male	1.85	1.32–2.58	0.00030
Age	1.00	0.99–1.01	0.79
Driver vs. passenger	1.40	0.98–2.03	0.066
Unemployed vs. employed/retired	0.91	0.57–1.44	0.69

Discussion

The original description of whiplash injury dates back to 1928 and Crowe. ⁸ Since the initial description, the injury has attracted widespread research and increased litigation rates. The term is controversial in both the medical and legal profession, currently referred to as whiplash associated disorder (WAD). It costs the United Kingdom over £2 billion per year and both diagnosis and treatment remain contentious. ⁹ Disproportionately represented in medico-legal claims, there is a large body of evidence on whiplash injuries to the neck. However, literature has so far largely neglected the documentation of other soft tissue injuries.

Medco Registration Solutions (Medco), a not for profit company, was established in 2015 in the United Kingdom by the Ministry of Justice. ¹⁰ It was designed to provide independence and accreditation within the medico-legal sector and to prevent claimant lawyers sourcing medico-legal reports from individuals or organisations with whom they had a financial link. Medco acts as a registry of individual experts and medical reporting organisations (MROs) who provide the relevant documentation for RTA soft tissue injury claims. All medical experts must be accredited by Medco such that they may provide the initial fixed cost medical report in a soft tissue injury claim. Further reforms, in the form of the Civil Liability Act, have been delayed until 2020. These reforms involve a tariff for fixed and much-reduced damages for collisions and limit for compensation. ¹⁰

Current legislation in the United Kingdom states that wearing a seatbelt is compulsory. In contrast, there is no legislation that makes the presence of airbags within the vehicle compulsory. Airbags provide protection by inflating very quickly and with a considerable amount of force to cushion the moving passenger. The deployment mechanism in itself can cause soft tissue abrasions and injuries. For this reason, only road traffic collisions where airbags were not deployed were considered in this series for analysis.

Sixty per cent of the collisions in our data set were rear collisions. Whilst the data set demonstrated a statistically significant difference between males and females reporting injuries, there was no gender difference in the location of injuries. This is congruent with published studies on whiplash-associated disorder that report no gender predisposition. ¹¹

Research involving whiplash-associated disorder has largely focused upon the cervical spine. However, a large number of claimants also experience thoracic or lumbar spine pain. Bilston et al. noted that the elderly had a higher risk of spinal injury compared to younger adults. ¹² Our data set demonstrated that patients with soft tissue thoracic and/or lumbar soft tissue injuries tended to be in younger adults. This is likely because of changing biomechanical tolerances with age and our inclusion criteria only assessing soft tissue injuries.

Hand and wrist injuries were almost exclusive to drivers, which is unsurprising. There are reports of carpal tunnel syndrome following car collisions in the existing literature. ¹³ Many in our cohort, especially older subjects, also showed symptoms suggestive of exacerbation of arthritis such as in the basal thumb joint.

Our data demonstrated no significant correlation between the side of the injury and the position of the individual in the car in knee injuries. It is already known that age is a risk factor, in addition to shorter stature and speed of impact. Whilst literature exists that documents fracture patterns with types of crashes ¹⁴ in front seat occupants, there is little documented literature on soft tissue injuries to knees. However, a 12.3% prevalence in our series show that knee soft tissue injury is a common complaint among these claimants especially drivers and front seat passengers.

Patients complaining of chest injuries were likely to have an associated shoulder injury. This highlights the importance of a thorough examination at initial presentation to medical services. These patients also have a higher risk of ongoing symptoms from a whiplash-associated disorder.

A statistically significant proportion of claimants in our series experienced psychological symptoms consistent with anxiety. A meta-analysis involving 4502 patients ¹⁵ with whiplash-associated disorder found that elevated psychological distress was associated with motor vehicle collisions. The increased psychological distress remained elevated for at least three years following the collision. Our data further highlight the importance of medical professionals considering psychological effects in addition to physical pathology to ensure that individuals are appropriately supported during the recovery period. It is well recognised that young females are twice as likely to be diagnosed with anxiety and at high risk of common mental health problems. ¹⁶ Our data set did not deviate from this and demonstrated that anxiety was more common in females, although we did not elicit any significance to the age of the individual. Given that there is still a social stigma associated with reporting mental health problems, it is not clear whether the gender difference may be confounded by this.

A 2018 meta-analysis ¹⁷ of 2989 road traffic collision survivors reported a 15.81% incidence of acute stress disorder. Other research has found that 10% of those involved in road traffic collisions may develop post-traumatic stress disorder (PTSD). Of note, this includes all types of crashes and not just the lower velocity or force collisions that our data focused upon. We could only extract a small amount of data regarding ongoing symptoms that fitted the DSM-V criteria of PTSD. Both anxiety and PTSD in our study were positively correlated with an increasing number of body parts injured. Psychological symptoms are well associated with the development of chronic pain.

Current NICE guidelines for PTSD are under review, but the draft for consultation recommends trauma-focussed cognitive and behavioural treatment, CBT, to adults with an acute stress disorder or clinically important symptoms of PTSD who have been exposed to one or more traumatic events in the last month. For children and young people, group-based CBT is recommended. ¹⁸ Given these recommendations, it may be prudent for those undertaking medico-legal work to collaborate with a psychologist to ensure a holistic approach.

The data set and results highlight the importance of a thorough history and examination with careful consideration of multiple injuries. The psychological effects of a collision should not be underestimated and a collaborative approach with a psychologist would be beneficial to explain the physical disability as well. The data set reports on soft tissue injuries, aside from those to the cervical spine, in motor vehicle collisions. Little data is currently available and, with the increasingly litigious culture within the United Kingdom, it is pertinent and timely to review associations of injuries. Further work needs to be addressed to the temporal nature of the soft tissue injuries to allow clinicians to inform claimants/patients appropriately. Additionally, Medco, who already collect data on injuries, should be able to provide further information in future on patterns of injury and its associations. Finally, with increasing regulation within the industry and the introduction of the Civil Liability Act, medico-legal providers may also see an increase in those attending with whiplash and associated injuries.

The data are not without limitations, and one of these is that the duration of symptoms could not be collated from reports. The study is from a single practice and thus may not be generally applicable, and of course only includes those who made claims. Psychological assessments were not corroborated by a psychologist and hence may not reflect the true picture.