Non-fatal spine injuries resulting from motorcycle

IATSSR-00159; No of Pages 7 IATSS Research xxx (2017) xxx–xxx

Contents lists available at ScienceDirect

IATSS Research

Research article

Non-fatal spine injuries resulting from motorcycle crashes Zarir Hafiz Zulkipli a,⁎, Siti Atiqah Mohd Faudzi a, Abdul Rahmat Abdul Manap b, Noor Faradila Paiman a a b

Malaysian Institute of Road Safety Research (MIROS), Lot 125, Jalan TKS 1, Taman Kajang Sentral, 43000 Kajang, Selangor, Malaysia Crash Engineering Consultant, No 299 Fasa 8, Taman Pelangi, 36700 Langkap, Perak, Malaysia

a r t i c l e

i n f o

Article history: Received 22 November 2016 Received in revised form 18 September 2017 Accepted 25 September 2017 Available online xxxx Keywords: Spinal injury Motorcycle crash Mechanism of injury Vertebral fracture

a b s t r a c t This study aims to determine spinal injury patterns and identify crash factors commonly associated with serious spinal injury as a result of motorcycle crashes. Data was retrospectively collected from motorcyclists sustaining spinal injuries from road crashes treated at Kuala Lumpur Hospital, Malaysia, over the 5-year period from 2005 to 2009. Each patient's injuries were analyzed by reviewing his or her medical records for radiographic imaging and computed tomography scans. A total of 151 patients were included in this study, of which, males accounted for over 87%. The first lower lumbar (L1) was the most commonly injured vertebral level, followed by the adjacent thoracic vertebra (T12). Fracture to the vertebral body without dislocation was found to be the most frequently observed spinal injury pattern. Injury severities for a majority of patients (65%) were measured at Maximum Abbreviated Injury Scale (MAIS) of 2. Serious spinal injury was associated with thorax or upper-extremity injury. Prevalence of lumbar spinal injury in the study reflects a predominantly low-speed crash among the motorcyclist in the region. Motorcyclists are at greater odd to sustain severe spinal injury when directly striking an object compare to striking the ground during the crash event. © 2017 International Association of Traffic and Safety Sciences. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction Motorcyclists are among the most vulnerable of all road users. Motorcycle travel is substantially more likely to result in injury than alternative vehicle travel. Furthermore, injuries associated with motorcycle travel are likely to affect the motorcyclist more severely than other vehicle occupants [1–2]. Motorcycle-related injuries have become a major health concern due to a worldwide increase in motorcycle use, especially in developing countries [3–5]. In Malaysia, motorcyclists now account for over half of all motorists, and 60% of total deaths from all road-traffic collisions involve a motorcycle [6]. While head injuries are the predominant cause of motorcycle fatalities, spinal injuries are equally devastating and conceivably more detrimental to surviving victims. Severe spinal injuries, particularly to the upper cervical region, are often lethal, while injuries involving the spinal cord frequently result in permanent disability. These injuries place excessive pressure upon not only health care systems, but also crash victims and their families [7–8]. A study by Zaloshnja et al. [9] has found that spinal injuries affect patients to a greater extent, both socially and financially, than other injuries. Reported incidences of traumatic spinal injury are disproportionately spread throughout the world, with developing countries [7–8] ⁎ Corresponding author. E-mail address: zarirhafi[email protected] (Z.H. Zulkipli). Peer review under responsibility of International Association of Traffic and Safety Sciences.

reporting larger scales of these incidences as compared to more developed countries [10–11]. However, previous studies involving motor-vehicle trauma have largely been epidemiological in nature and have mainly concentrated on car occupants. Relatively little data exists regarding the aetiology of spinal injuries resulting from motorcycle accidents. Furthermore, previous work has generally focused on specific spine levels (e.g., cervical, thoracic or lumbar) [12–14]. One study however, by Robertson et al., [10] did include the entire spine, although it only assessed injury patterns and clinical outcomes and did not identify factors contributing to severity of spinal injury. In addition to this lack of data, little is known about the epidemiology or spectrum of spinal injuries sustained in motorcycle crashes either in Malaysia or developing countries throughout Asia. The injury patterns in this region are postulated to differ from those in developed countries due to the use of dissimilar makes of motorcycle in the latter. The aim of this work was therefore to determine patterns of spinal injury in patients hospitalized ensuing motorcycle crashes at Kuala Lumpur Hospital, Malaysia, and to identify risk factors for serious spinal injury. 2. Patients and methods Data was collected retrospectively from all motorcycle-crash victims admitted to the Orthopedic Department of Kuala Lumpur Hospital (HKL) sustaining spinal injury during the period from January 2005 to December 2009. The study hospital serves a city with a population of 1.6 million and the vast majority of its orthopedic trauma cases were

https://doi.org/10.1016/j.iatssr.2017.09.001 0386-1112/© 2017 International Association of Traffic and Safety Sciences. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Please cite this article as: Z.H. Zulkipli, et al., Non-fatal spine injuries resulting from motorcycle crashes, IATSS Research (2017), https://doi.org/ 10.1016/j.iatssr.2017.09.001

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Z.H. Zulkipli et al. / IATSS Research xxx (2017) xxx–xxx

from this populace. The protocol of the study was approved by MIROS' Research Committee and Research and Ethic Committee, National Institute of Health, Ministry of Health Malaysia. Spinal injury was defined as trauma to the cervical, thoracic or lumbosacral region. Medical records for each patient were assessed for the following data according to approaches described by Pike [15] and similar previous studies [16–17]. Name or identifying information; date of injury; age at the time of injury; gender; neurological level of lesion; mechanism of injury; patient exposure to alcohol or drugs; and presence of associated injuries to the head, chest, abdomen or extremities were noted. In order to confirm injury types and characteristics, photographs and diagrams such as plain radiographs (X-rays), computed tomography (CT) scans and magnetic resonance imaging (MRI) scans were collected from patient files where available. Additionally, opinions were sought from orthopedic surgeons. Several variables relating to the collision were also recorded; these included, type of crash, mode of impact, and model of vehicles involved. Additionally, details on whether drivers or pillion passengers were affected were noted. To complement data from medical reports, a standard telephone-interview script and protocol was developed to seek further information from patients, especially on crash-related variables. Police investigation reports were also obtained to enhance assessment reliability. Crash type was further categorized as single-vehicle (with a motorcycle being the only vehicle involved in the crash) or multiple-vehicle (involving a motorcycle and other vehicles). ‘Impact mode’ was defined as the principal direction of force impacting the motorcyclist during the crash. ‘Contact made by the motorcyclist’ was defined as any impact to his or her body subsequent to being thrown off the motorcycle. The Abbreviated Injury Scale (AIS; 2005 revision, updated 2008) was used to assess spinal injury severity. Patients with AIS measurements of three or higher were considered to have incurred severe spinal trauma, whereas injuries that scored two or below were regarded as mild to moderate [18]. An Injury Severity Score (ISS) was also calculated for each patient. These ISS scores were grouped into minor (ISS 1–8), moderate (ISS 9–15) and severe (ISS ≥ 16) categories in accordance with convention [19]. Injury profiles, patient images (X-rays and computed tomography (CT) or magnetic resonance imaging (MRI) scans) and the established literature allowed classification of each injury by predominant injury type for each spinal region. Data obtained was analyzed using SPSS, version 17 (IBM Corporation, Kuala Lumpur, Malaysia). Associations of spinal injury outcomes with patient and crash characteristics were assessed using the Chisquare test. All statistical tests were considered significant at the p b 0.05 level. Missing patient data for specific variables excluded only from analyses based on those variables; numbers may therefore vary for some analyses.

Fig. 1. Gender and age distribution of the study population.

spine (13 patients). None of the patients studied sustained concurrent injuries to the cervical and lumbar spine or to all three regions together. Fig. 2 shows the distribution of injuries across all spinal regions by vertebral level. The most commonly injured vertebral level was the first lumbar (L1) followed by the adjacent thoracic vertebra (T12). The most common spinal injury was fracture of the vertebral body without dislocation (144 injuries), followed by spinal cord contusion or compression (48 injuries), and transverse process fracture (19 injuries) was the third most prevalent spinal injury. Table 1 shows the distribution of spinal injuries by spinal region. Analysis of our patient population has identified flexion with compression as the predominant cervical spinal injury type. Fig. 3 illustrates an example of cervical flexion-compression injury found in the study. The most prevalent type of injury to the thoracic spine was compression and dislocation with several instances of burst fractures with intrusion into the spinal canal (Fig. 4). Similarly, the most frequently observed injuries for the lumbar spine were compression injuries, although these injuries had reduced occurrences of dislocation. Fig. 5 depicts a case of lumbar spine compression identified in this study.

3. Results 3.3. Injury severity and outcome 3.1. Demographics The study group (151 patients) consisted of 129 riders (85.4%) and 22 pillion passengers (14.6%). Males accounted for 87.4% of surveyed patients and females 12.6% (132 and 19, respectively). The mean age of the study population was 33.1 years (range 15–75 years). The majority of male patients sustaining spinal injuries were between 21 and 30 years of age, whereas the proportion of injured females was constant across all age groups (Fig. 1). 3.2. Injury patterns Injuries specifically to the cervical spine were observed in 49 patients (32.5%), thoracic spine in 27 patients (17.9%), and lumbosacral spine in 57 patients (37.7%). Multiple-region spinal injuries were noted in 18 patients (11.9%) and consisted of simultaneous injuries to the cervical and thoracic spine (5 patients) or thoracic and lumbar

Table 2 lists the distribution of spinal injury severity and outcome of each spinal region. Spinal injury of Maximum AIS 2 (MAIS 2) was suffered by the majority of patients assessed (99 of 151). Spinal injury of MAIS 5 occurred the most at thoracic spine and resulted in neurological deficit more frequently than that of any other spinal region. The overall mean ISS of patients with spinal injury was 11. However, patient with thoracic spine injury and multiple spine region injury recorded a significantly higher mean ISS than the overall mean ISS with 17.7 and 18.1 respectively. In addition, the overall mean and median hospital stays were 26.3 days and 7.0 days respectively (range, 1– 305 days). 3.4. Risk of serious spinal injury in patients with associated injuries Of the 151 patients with spinal injuries in our cohort, only 36% sustained associated injuries of AIS 2 or greater. The most common



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injury than motorcyclists who impacted the ground. Also, there were no significant differences in spinal injuries between helmeted and non-helmeted motorcyclists. The most frequent type of crash was multiple vehicle collision (MVA) compared to single-vehicle collision (SVA). Common impact modes were skidding and frontal impact; although, impact mode made no significant difference to the severity of spinal injuries in the study. 4. Discussion

Fig. 2. Distribution of injuries across all spinal regions by vertebral level.

associated injuries were fractures to lower and upper extremities, thorax injuries and head injuries. When associated injuries were cross-tabulated with spinal injury, only thorax and upper-extremity injuries were found to be significantly linked with serious spinal injury. As shown in Table 3, the proportions of serious spinal injury were higher in patients who sustained MAIS 2–5 thoracic injury (p = 0.031) and MAIS 2–5 upper-extremity injury (p = 0.038). 3.5. Crash factors Table 4 shows the univariate analysis of crash factors in relation to spinal injury severity. Motorcyclist direct contact was the only crash factor that was found to significantly associate with the severity of injury. Motorcyclists who made direct contact with another object during a collision were almost three times more likely to sustain a serious spinal Table 1 Distribution of spinal injuries by region. Region of injury

C1-C2 subluxation Odontoid fracture Transverse process fracture Pedicle fracture Laminar fracture Spinous process fracture Facet dislocation Spondylolithesis Vertebral body dislocation Vertebral body fracturea with dislocation without dislocation Prolapsed intervertebral disc Soft-tissue injury (strain/ligament) Spinal cord contusion/compressionb Sacrum fracture

Cervical

Thoracic

Lumbosacral

Total

No. of injuries

No. of injuries

No. of injuries

No. of injuries

6 2 4 5 9 9 4 1 2

– – 5 1 1 2 – – 2

– – 10 1 – 4 – 2 4

6 2 19 7 10 15 4 3 7

2 35 3 4 20 –

7 51 – – 19 –

3 58 5 2 9 7

12 144 8 6 48 7

a Burst fracture occurred in 15 patients in the thoracic region, 11 in the lumbar and 6 in the cervical. b With either fracture or dislocation/both fracture and dislocation/neither fracture nor dislocation.

Patient demographics in this study are comparable to those in previous studies, although the proportion of pillion riders in the current study was slightly greater than that observed elsewhere [8,10,20]. The predominance of male adults in our study reflects the patterns of motorcycle usage within the Malaysian population. Data analysis revealed that the majority of injured motorcyclists sustained trauma to the lumbar and cervical spine; the two most-frequently injured vertebrae were T12 and L1 (the thoracolumbar junction). This pattern resembles results of a study by Pedram et al. [20] in Iran. Most studies however, particularly European and American, have revealed a prevalence among motorcycle collision victims of thoracic spinal injury, with the mid-thoracic spine (T6-T7) most frequently affected [10,21,22]. Though this difference can be attributed to our data, which excluded crash fatalities, we believe that their inclusion would only increase the number of cervical spinal injuries, as previously reported [16,23]. The diverse nature of injury patterns suggests the involvement of varied causes of injury. Injury to the thoracic spine, especially the midsection, is associated with high energy transfer; great force is required to injure the thoracic spine, which is well-protected by the rigid rib cage [24]. This is usually the result of direct impact to the thoracic spine or concentrated axial loading to the spinal column at the thoracic spine. A motorist may sustain this type of injury after being thrown from his vehicle and striking a rigid object with the kyphotic curve of the thoracic spine [22]. Incidents such as this are a more common occurrence among motorcyclists in Europe and the United States because of the large size and high power of motorcycles in these locations [25]; collisions are also sustained at high speed so that crashes often involve high energy transfer and motorcyclist can be catapult from the motorcyclist upon collision [22]. In contrast, developing countries such as Malaysia, typically use smaller motorcycles with low-powered engines, usually for urban or short distance commutes. Crashes involve lower energy transfer due to their reduced speed and because other vehicles also travel in lesser speed in urban areas. A study by Matzsch and Karlsson had shown that smaller motorcycle tends to cause less severe injury due to the lesser speed and energy involved in smaller motorcycle crash [26]. These low speed collisions often involve a motorcycle colliding with another vehicle and the motorcyclist being thrown to the ground. This fall could be injurious to the spine in two ways. Firstly, if the motorcyclist falls head first, the cervical spine could undergo abnormal and extreme movements such as hyper-flexion or hyper-extension which can put the spine under huge stress and lead to fractures. Ooi et al. [16] indicated that cervical flexion and extension movements are the most frequently observed cervical injuries among motorcyclists. Our study supports these findings with identical injury patterns that include a high frequency of C5-C6 vertebrae and posterior spine column fractures (pedicles, lamina, facet joints, and spinous process). Secondly, the lumbar spine could undergo axial loading which can cause compression fractures if the motorcyclist falls from the motorcycle and onto their buttocks. This susceptibility to compression is due to the greater weight acting on each individual vertebral body. The most common vertebra affected is L1, along with its adjacent vertebrae L2 and T12 [11,20, 27]. A study by Pedram et al. [20] revealed that lumbar spinal fracture is predominantly associated with falling and road-traffic crashes especially involving motorcyclists and pedestrians. This is supported by our


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Fig. 3. X-ray (left) and MRI scan (right) of a patient showing C5 vertebral fracture resulting from flexion-compression.

findings of elevated levels of lower-extremity injury in association with the lumbar spine. Our study shows higher incidences of neurologic deficit (27.8%), in comparison to a study by Robertson et al. [10] (19.8%). This is attributed to the higher cases of cervical spine injury with neurological deficits in our data. Brandser and el-Khoury [28] revealed that approximately 50% of patients with traumatic thoracic spine fractures have accompanying neurological deficits. Yet, the incidences of neurological deficits among motorcyclists with traumatic thoracic spine fracture are even greater ranging from 69%–86% [13,20]. Our study mirrors these high

cases of neurologic deficits accompanying thoracic spine. This a cause for concern because delay in diagnosis may be associated with progressive neurological deficit [29]. Furthermore, due to strong links with other thoracic injuries, such as lung contusion or hemopneumothorax, delay in diagnosis could cause further complications [30]. In general, patterns of associated injuries observed in our study are consistent with those in other studies, with the majority of injuries occurring in the upper and lower limbs [10,18]. The significant links between thoracic and upper-extremity injuries, and serious spinal injury, is due to the anatomical connection of these sites to the cervical and

Fig. 4. CT scan of a patient showing T1-L1 vertebral fracture-dislocation.



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Fig. 5. X-ray (left) and CT scan (right) of a patient showing burst and compression fractures of the L1 vertebra.

thoracic spine. Some studies have suggested relationships between lumbar fractures and abdominal injuries [31–32] and between cervical spinal injuries and those to the head [33–34]. However, these relationships were not observed in our study. Vives et al., [35] in a study of pedestrian spinal injuries, inferred that the absence of these associations might reflect the fact that spinal injuries are commonly the result of flexion, axial load, distractive flexion and shear movement of the spine column; whereas, injuries to the head, chest and pelvis are the consequence of direct force. Though our crash-characteristics data was incomplete, the data available offers an insight into the relationship between certain crash factors and the severity of spinal injury. Goslar et al. [36] discovered no significant link between location of spinal fracture and helmet use. We similarly find no significant difference in severity of injury between helmeted and non-helmeted motorcyclists. Despite this, other studies have identified helmet use relating to reductions in spinal, especially cervical injuries [12,37]. While the use of protective jacket or back

Table 2 Distribution of spinal injury severity and outcome by region injured. Injury severity and outcome

Spinal injury severity MAIS 1 MAIS 2 MAIS 3 MAIS 4 MAIS 5 Neurological deficita Yes No Injury Severity Score (ISS) 1–8 9–15 ≥16

Table 3 Injury patterns of spinal regions sorted by severity of associated injuries.

Cervical

Thoracic

Lumbosacral

Multiple

Overall

No. of patients

No. of patients

No. of patients

No. of patients

No. of patients

4 25 10 5 5

0 14 1 3 9

0 48 5 2 1

0 8 2 3 5

4 99 18 12 20

15 34

13 14

7 49

7 12

42 109

26 13 10

11 5 12

42 9 4

6 4 9

protector is gaining popularity elsewhere none of the patient in the study was found to use them. Although there is very limited information on the efficacy of back protectors against the spinal injuries [38], the back protectors may help lessen the direct blow to the back upon motorcyclist striking an object after falling off the motorcycle. Singh et al. [39] demonstrated that thoracic spinal injuries are less likely to occur in intoxicated individuals; however, we unable to substantiate this in our data. Ooi et al. [16] have shown that impact-mode influences the severity of cervical spinal injury; in our current study however, we found no significant association. A possible explanation for this is lack of restraints on a motorcyclist, who might therefore easily be thrown from the motorcycle following impact. Motorcyclists might then be subjected to more substantial impact, striking dangerous roadside objects or even other vehicles. Initial impact may be minor and less significant compared with any secondary impact by a falling motorcyclist. We discovered that the likelihood of obtaining serious spinal injury increases

85 31 35

MAIS — Maximum Abbreviated Injury Scale. a 14 injuries resulted in tetraplegia, 13 in paraplegia and 3 in partial sensory loss.

Associated injuries

Head injury MAIS 0–1 MAIS 2–5 Thoracic injury MAIS 0–1 MAIS 2–5 Upper-extremity injury MAIS 0–1 MAIS 2–5 Lower-extremity injury MAIS 0–1 MAIS 2–5

Spinal injury

Statistical significance

MAIS ≤ 2 (n = 101)

MAIS ≥ 3 (n = 50)

Total (n = 151)

n%

n%

n%

97 (67.4) 4 (57.1)

47 (32.6) 3 (42.9)

144 (100) 7 (100)

Fisher's exact test P = 0.685

96 (69.6) 5 (38.5)

42 (30.4) 8 (61.5)

138 (100) 13 (100)


94 (69.6) 7 (43.8)

41 (30.4) 9 (56.3)

135 (100) 16 (100)

a

92 (67.6) 9 (60.0)

44 (32.4) 6 (40.0)

136 (100) 15 (100)


Chi square test P = 0.038

MAIS – Maximum Abbreviated Injury Scale. a X2 = 4.33, df = 1.


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Table 4 Association of crash factors with spinal injury severity. Crash factor

Time Day Night Position Pillion Rider Helmet Yes No Alcohol influence Yes No Crash type Motorcycle Passenger car Lorry SVA Impact mode Side Rear Skidding Frontal Motorcyclist impact Contact with ground Contact with objects

Spinal injury

p

OR

95% CI

76 (100) 49 (100)

0.86

1.00 1.07

Reference 0.50–2.30

4 (18.2) 46 (35.7)

22 (100) 129 (100)

0.12

1.00 2.49


31 (62.0) 5 (55.6)

19 (38.0) 4 (44.4)

50 (100) 9 (100)

0.72

1.00 1.31


12 (70.6) 89 (66.4)

5 (29.4) 45 (33.6)

17 (100) 134 (100)

0.73

1.00 1.21


11 (73.3) 48 (64.9) 3 (60.0) 35 (67.3)

4 (26.7) 26 (35.1) 2 (40.0) 17 (32.7)

15 (100) 74 (100) 5 (100) 52 (100)

0.92

1.00 1.49 1.83 1.34

Reference 0.43–5.15 0.22–15.33 0.37–4.82

13 (86.7) 11 (73.3) 24 (66.7) 23 (60.5)

2 (13.3) 4 (26.4) 12 (33.3) 15 (39.5)

15 (100) 15 (100) 36 (100) 38 (100)

0.34

1.00 2.36 3.25 4.24

Reference 0.36–15.45 0.63–16.79 0.84–21.52

48 (75.0) 21 (51.2)

16 (25.0) 20 (48.8)

64 (100) 41 (100)

0.014

1.00 2.86


MAIS ≤ 2 (n = 101)a

MAIS ≥ 3 (n = 50)a

Total (n = 151)a

n%

n%

n%

50 (65.8) 33 (67.3)

26 (34.2) 16 (32.7)

18 (81.8) 83 (64.3)

MAIS – Maximum Abbreviated Injury Scale, SVA – Single Vehicle Crash. a Column does not sum to total due to missing data points.

three-fold when falling motorcyclists strike another object rather than impacting the ground during a collision. Our findings comparable to the observations made in a recent study by Daniello and Gabler [40] showing that collision with a roadside fixed object is at least four times more likely to result in a fatality than collision with the ground. There are several limitations to our study. First, as we considered only surviving patients, our findings are rather limited and do not apply to the entire spectrum of spinal injury among motorcyclists. Due to the nature of retrospective and hospital-based studies, we could access only limited crash-related variables: police reports are usually incomplete for non-fatal cases and crash variables were not routinely recorded in medical notes. Out of all the cases only 25% were able to be matched with police reports whilst only 75% of the patients were managed to be interviewed. In spite of this, we feel that the combined dataset provides us with the ability to investigate and compare important crash characteristics which is not ordinarily available. 5. Conclusions The most common spinal injury sustained by motorcyclists is injury to the lumbar spine with the thoracolumbar vertebrae being the frequently affected segment. The prevalence of low speed motorcycle crashes in the region could be a factor in the difference in injury patterns observed in this study compared to previous works. Interesting findings relating to the association of thorax or upper-extremity injuries with serious spinal injury may help clinicians in their assessment of motorcycle trauma patients. Motorcyclists are at greater risk of sustaining severe spinal injuries when they directly strike an object compared to striking the ground during a crash. Conflict of interest statement No conflict of interest exists for any of the authors, financial, personal or otherwise, and there are no disclosures to be made.

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