E-Scooters and Craniofacial Trauma: A Systematic Review

Abstract

Study Design: Systematic review. Objective: Standing electric scooters (e-scooters) provide a cheap and environmentally friendly transport alternative, but also elicit substantial concern regarding their volume of associated injuries especially in the craniofacial region. This review aims to explore the demographics, risk factors, types of injury and surgical management of craniofacial trauma associated with e-scooters. Methods: PubMed and Scopus databases were systematically searched. Inclusion criteria were clinical studies investigating craniofacial trauma associated with e-scooters. Exclusion criteria were duplicates; non-English publications; non-full-text publications; studies with insufficient data. Results: Of the 73 articles identified, 10 eligible articles representing 539 patients were included. The mean age was 31.5 years. Most cases were male (63.7%). Common risk factors were alcohol/drug intoxication, absence of distal extremity injuries and lack of helmet use. The most common mechanism of injury was mechanical falls (72.4%). The most common facial fracture pattern was middle third fractures (58.3%). Surgical management was required for 43.3% of fractures. Other types of injuries reported were traumatic brain injuries (17.6%), soft tissue injuries (58.3%), dental injuries (32.9%) and ophthalmological injuries (20.6%). Conclusions: The findings of this review suggest common presentations for craniofacial trauma associated with e-scooters. Robust longitudinal evaluations with standardised descriptions of types of injuries are required. Gaps in knowledge relate to surgical management, post-operative complications and associated risk factors.

Introduction

Standing electric scooters (e-scooters) provide a cheap and environmentally friendly transport alternative, but also elicit substantial concern regarding their volume of associated injuries. The rapid uptake of e-scooters in the developed world since their 2017 ride-sharing launch corresponds with increasing reports of associated injuries from Australia, [1] Denmark, [2] England, [3] Finland, [4] France, [5] Germany, [6] New Zealand, [7] Singapore, [8] South Korea, [9] Sweden [10] and the United States. [11]

Previous retrospective analyses have described a wide range of craniofacial injuries associated with e-scooters, including bony fractures, dental injuries, soft tissue injuries and traumatic brain injuries. [4,12] Injury to the craniofacial region is especially concerning as involvement of adjacent vital intracranial structures may be life-threatening, [13] injury to local sensory or motor structures can impair function, [13] and the visibility of facial defects can have important psychological impacts. [14]

This will be the first systematic review exploring this emerging area of concern. It aims to investigate the demographics, risk factors, types of injury and surgical management of craniofacial trauma associated with e-scooters. Better understanding of this area will aid preventive strategies and surgical planning, resulting in improved patient care and resource allocation.

Materials and Methods

Search Strategy

This review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement. [15] Systematic searching of PubMed and Scopus databases was performed in 2022 February for English-language studies using the search strategy ‘(electric OR motorised) scooter AND facial’ with no restrictions on study design. The reference lists of identified studies were also assessed for relevant studies (cross-referencing).

Eligibility Criteria

Inclusion criteria were clinical studies investigating craniofacial trauma associated with e-scooters. Exclusion criteria were duplicates; non-English publications; nonfull-text publications; studies with insufficient data on the demographics, risk factors, types of injury or surgical management of craniofacial trauma associated with e-scooters.

Data Collection

After removal of duplicates and non-English records, screening by title and abstract, and assessment of full-text publications to exclude irrelevant records, the remaining studies were deemed eligible for inclusion. The following data were extracted from the included studies: demographics, risk factors, types of injury and surgical management. There was independent identification and assessment of studies, with discussion for the final eligible selection and data extraction.

Quality Assessment

Quality assessment of individual studies was performed using the Methodological Index for Non-Randomised Studies (MINORS). [16]

Results

Study Selection

The study selection process is outlined in Figure 1. Systematic database searching and cross-referencing retrieved 73 records, of which 56 remained after removing duplicates.

There were no non-English records. Screening by title and abstract excluded 26 irrelevant records. Assessment of 30 full-text publications resulted in the exclusion of 20 articles due to insufficient data specific to craniofacial trauma associated with e-scooters. The remaining 10 studies were deemed eligible for inclusion.

Quality Assessment

The overall quality of evidence was moderate (

Table 1. Quality Assessment Using the Methodological Index for Non-Randomised Studies (MINORS).

). All studies were retrospective case series involving data collection at a single timepoint, and follow-up criteria were not applicable. Study aims and patient selection were generally well described, with the use of appropriate endpoints. None of the studies reported blinding for outcome assessment. Only 2 studies described statistical analyses.

No quantitative outcome-level assessment was performed due to the overall descriptive nature of the findings and minimal reporting of effect estimates.

Demographics

There were 539 patients with e-scooter-associated craniofacial trauma represented in the 10 included studies, out of a total of 745 patients (

Table 2. Demographics Reported in Ten Studies.

). Age was reported in 6 studies (n = 419), with a mean of 31.5 years. [5,9,17,18,19,20] Gender was reported in 7 studies (n = 430), with 63.7% of patients being male (n = 274). [5,9,17,18,19,20,21] Data from the United States, [17,22,23] Germany, [18,21] Finland, [4] France, [5] New Zealand [20] and South Korea [9,19] were included. Seven studies included only data subsequent to the local launch of ride-sharing e-scooters, [4,17,18,20,21,22,23] while 3 studies included data from before and after the transition. [5,9,19]

Risk Factors

Significant risk factors for e-scooter-associated craniofacial trauma were absence of distal lower limb injuries (P < .01), absence of distal upper limb injuries (P = .03) and alcohol/ drug intoxication (P < .01). [17] Lack of helmet use was a commonly reported risk factor.

Data on distal limb injuries were reported in 1 study. [17] There were distal lower limb injuries in 2.6% of patients with craniofacial trauma (n = 1 of 38) and 21.3% of patients without craniofacial trauma (n = 27 of 127) (P < .01). There were distal upper limb injuries in 15.8% of patients with craniofacial trauma (n = 6 of 38) and 35.4% of patients without craniofacial trauma (n = 45 of 127) (P = .03).

Data on alcohol use, drug use and/or lack of helmet use were reported in 8 studies [5,17,18,19,20,21,22,23] (

Table 3. Risk Factors (Alcohol Use, Drug Use, Lack of Helmet Use) Reported in Eight Studies.

). Alcohol use was reported in 41.0% of patients (n = 139 of 339) with a range of 9.6% to 82.1% across 7 studies. [5,17,18,19,20,21,23] Drug use was reported in 5.7% of patients (n = 13 of 227) with a range of 0% to 6% across 3 studies. [5,17,23] Lack of helmet use was reported in 87.6% of patients (n = 282 of 322), with a range of 47.4% to 100% across 5 studies. [5,17,19,22,23] Only 1 study compared the presence of these risk factors in patients with and without craniofacial trauma. [17] Alcohol/drug intoxication was a significant risk factor, being present in 52.6% of patients with craniofacial trauma (n = 20 of 38) compared to 4.7% of patients without craniofacial trauma (n = 6 of 127) (P < .01). [17] Lack of helmet use (n = 8 of 38, data missing for 30 patients) was not found to be a significant risk factor due to the missing data. [17]

Types of Injury

Data on mechanism of injury were reported in 3 studies (n = 145) [17,19,23] (

Table 4. Mechanism of Injury Reported in Three Studies.

). The most common mechanism of injury was mechanical falls (n = 105, 72.4%).

Specific craniofacial injuries described in the 8 studies were bony fractures, traumatic brain injuries (TBI), soft tissue injuries, dental injuries and ophthalmological injuries (

Table 5. Number of Patients With Craniofacial Injuries Reported in Ten Studies.

).

A total of 398 bony fractures were reported in the ten studies. [4,5,9,17,18,19,20,21,22,23] This consisted of 315 fractures in 182 patients across seven studies and 83 fractures in an unspecified number of patients in the other studies. Middle third fractures were the most common (n = 232, 58.3%), followed by lower third fractures (n = 142, 35.7%), while upper third fractures (n = 18, 4.5%) and calvarial/skull base fractures (n = 6, 1.5%) were rare (

Table 6. Fracture Pattern Reported in Ten Studies.

).

TBI were reported in 17.6% of patients (n = 95 of 539) in ten studies. [4,5,9,17,18,19,20,21,22,23] Only 1 study reported these in association with bony fractures (n = 2 of 11). [21] The proportion of combined TBI and facial fractures were unclear in the other studies. Concussion (n = 50, 52.6%) [4,9] and intracranial bleeding (n = 35, 36.8%) [4,5,9,17,18,19,20,21,22,23] were the most common TBI reported.

Soft tissue injuries were reported in 58.3% of patients (n = 252 of 432) and dental injuries were reported in 32.9% of patients (n = 142 of 432) in 8 studies. [4,5,9,17,18,20,21,22] Only 1 study reported these in association with bony fractures (n = 11). [21] It was unclear if the soft tissue and dental injuries occurred concurrently with bony fractures in the other studies.

Ophthalmological injuries were reported in 20.6% of patients (n = 7 of 34) in 1 study. [23] These consisted of 1 massive retrobulbar haemorrhage, 1 intraretinal haemorrhage and 5 lid lacerations.

Surgical Management

Data on surgical management of e-scooter-associated craniofacial trauma were reported in 8 studies [4,5,9,18,19,20,22,23] (

Table 7. Surgical Management Reported in Eight Studies.

). Surgical management was required for 43.6% of patients across 5 studies, [5,9,18,19,23] and for 43.3% of fractures across 5 studies. [4,9,18,20,22] Only 1 study (n = 30) reported data on risk factors predisposing surgical management, and concluded that alcohol involvement was not significantly associated with the decision for operative vs non-operative management. [20] There were no data reported on post-operative complications.

Discussion

This is the first PRISMA-guided systematic review exploring the demographics, risk factors, types of injury and surgical management of craniofacial trauma associated with e-scooters.

E-scooter use demographics favour a younger adult population with an approximate 2:1 male-to-female ratio, [24] which is reflected in this review with patients having a mean age of 31.5 years and 63.7% being male. Significant risk factors for these injuries were alcohol/drug intoxication (P < .01) and the absence of distal extremity injuries (P ≤ .03). Lack of helmet use was also a common risk factor, with helmet use reported in less than 1 in thirty patients. These risk factors are similar to those reported for bicycle and electronic bicycle (e-bike) accidents, where traumatic brain injury (TBI) is significantly more likely in the setting of alcohol intoxication. [25] Helmet use is also an established significant protective factor in bicycle accidents against head injuries [26] and facial fractures. [27] Alcohol causes impaired judgement, as well as compromised neuromuscular reflexes for head protection such as an outstretched limb to brace against a fall, which was the most common mechanism of injury reported in this review. The latter corresponds with the absence of distal extremity injuries as a significant risk factor. Additionally, intoxicated patients have been found to be significantly less likely to wear helmets. [28] Awareness of these risk factors contributes to prevention strategies and improved screening for such injuries in e-scooter accidents, with the aim of improving patient outcomes.

These risk factors can also have important legal implications, in terms of local regulation and commercial promotion. Of the ten studies included, 7 were conducted after the local launch of ride-sharing e-scooters, which was 2017 in the United States, [17,22,23] 2018 in New Zealand [20] and 2019 in Finland [4] and Germany [18,21]; while 3 studies included data before and after the transition, which was 2018 in France [5] and South Korea. [9,19] This reflects growing interest in the relatively recent phenomenon of e-scooter injuries. Accordingly, there are still significant and evolving variations in national legislations relating to categorical definition of e-scooters as a micro-vehicle and allowed areas of use, helmet use and insurance laws, as well as speed and age limits. [24] From a commercial viewpoint, the degree of emphasis that e-scooter companies place on safety for their products and campaigns is an important consideration. Content analyses of e-scooter market leader Bird’s Instagram account in 2017–2019 revealed minimal photographic or textual feature of protective gear, with concerns that this may normalise unsafe riding behaviours in e-scooter users. [29,30] This is also an evolving space, with Bird’s current website displaying numerous prominent photographic and textual mention of helmet use. [31]

The types of injuries described in this review consisted of bony fractures and TBI, as well as soft tissue, dental and ophthalmological injuries. Almost 1 in 5 patients had a TBI (n = 95 of 539) but only 2 patients were explicitly reported to have had concomitant TBI and facial fractures. This is an important distinction due to the significant potential for morbidity and mortality in these combined injuries, with common patient factors being males in their thirties, traffic accidents and middle third fractures. [32] These were also commonly reported demographics in this review, with a 63.7% male proportion and an average age of 31.5 years, all mechanisms of injury being e-scooter accidents, and the most common fracture pattern being middle third fractures. Surgical delay is a significant risk factor for complications in patients with combined TBI and facial fractures, so increased awareness is important for prophylactic management of post-operative sequelae. [32] In this review, surgical management was required for approximately 4 in ten patients for facial fractures; however, there were minimal data reported for risk factors predisposing surgical management, and none for post-operative complications. Soft tissue and dental injuries were common, and represent important subsets of craniofacial trauma due to associated functional and aesthetic implications. Ophthalmological sequelae of e-scooter accidents have been understudied and should be an important area of future research in considering the potential for substantial visual morbidity.

This study has several limitations. At the review level, the small number of included studies makes it difficult to draw firm conclusions from the findings, although they can contribute to future research direction. This is particularly relevant to the lack of studies investigating risk factors for surgical management or post-operative complications, as well as variation in reporting in relation to the review’s parameters of interest. However, this is unsurprising considering the recent nature of e-scooter use, and more comprehensive longitudinal studies relevant to this area may be anticipated in the near future. At the study level, quality assessment with MINORS found a moderate level of evidence overall. Areas for future improvement include prospective data collection, prospective sample size calculation and unbiased endpoint assessment.

In conclusion, the findings of this review suggest common presentations for craniofacial trauma associated with e-scooters. Important risk factors are alcohol/drug intoxication, absence of distal extremity injuries and lack of helmet use. Further investigations utilising robust longitudinal designs with standardised descriptions of types of injuries are required. Gaps in knowledge relate to surgical management, post-operative complications and associated risk factors.