The popularity of e-scooters is continuously increasing, so is the number of e-scooter-associated injuries. In our study, we observed a noticeable rise of e-scooter-associated ER admissions from 13 in summer 2018 (May–September) to 116 in the respective period in 2019. This corresponds to an increase of 892% of e-scooter-associated injuries in Vienna, Austria.
While the severity of injuries varied in our patients (mean ISS 3.4 [1–27]), 40.6% sustained a major injury (fracture, dislocation, intracranial haemorrhage or concussion). Eleven patients presented with an ISS ≥ 9 and 2 further patients with an ISS ≥ 16. Interestingly, we found a considerable increase of ISS with age irrespective of sex. Indeed, patients presenting with an ISS ≥ 9 were significantly older than less severely injured patients. This emphasizes the fact that e-scooter-associated injuries are beyond benign and should be considered as high-energy trauma injuries with potentially life-threatening extent.
With respect to the anatomic area, we found the highest number of e-scooter-associated injuries for the upper extremity (53.1%). As similar trend sports (e.g. riding a micro-scooter or roller-skating) typically cause fractures of the wrist region, the authors usually recommended wrist protectors for the prevention of these distinct injury patterns [6, 7]; so did Ishmael et al.  by reporting on e-scooter-associated injuries requiring surgery, as 11 out of 75 patients sustained wrist fractures. Interestingly, we did not find a typical injury pattern for e-scooter-associated injuries affecting the wrist. Indeed, elbow fractures were more likely than wrist fractures (11 versus 3) in our patients. While Ishmael et al.  recommended the use of wrist guards for e-scooter riders, based on our numbers, the overall benefit might be only marginal.
The use of protective gear is worthwhile considering, given the high number of head injuries observed in our patients: we found the head to be at major risk for e-scooter-associated injuries, as 40.6% of the patients sustained an injury in this region with 43.7% sustaining a major head injury. These findings go in line with the report by Trivedi et al., who had observed 40.2% head injuries studying 249 e-scooter-associated injuries .
At the same time, the city of Brisbane passed a law for compulsory helmet use for e-scooter riders in January 2019. Interestingly, Mitchell et al. studied the incidence of e-scooter-associated injuries in Brisbane from November 2018 to January 2019, covering the time when the use of helmets became mandatory. Doing so, the related effect was considerable as the authors observed a subsequent helmet use in 46% of their patients. The authors further concluded that the use of a helmet at the time of injury significantly decreased the risk of sustaining a head injury compared to patients not wearing a helmet . This goes in line with reports studying the protective potential of helmets in other road users. Olivier et al.  presented similar findings reporting that helmet use while riding a bicycle is associated with a significant reduction of head injuries, corresponding to an odds ratio of 0.49 by the use of a helmet. Namiri et al. reported more than one-third of all e-scooter-associated injuries affecting the head region, leading to more than double the rate of head injuries, related to bicycle injuries [4, 12].
Currently available data on head injuries in e-scooter riders report heterogeneous numbers being as high as up to 40.2% [3, 9, 13]. Unlike in Brisbane, Australia, the use of a helmet is not mandatory for riding an e-scooter in any European capital. To this end, a law for compulsory use of helmet for e-scooter riders could lead to a significant reduction of e-scooter-associated head injuries and seems of utmost importance.
Several authors have already reported increased numbers of ER admissions during the evening and nighttime [9, 14]. Doing so, Trivedi et al.  reported that 56.6% of e-scooter-associated injuries occurred between 3.00 pm and 11.00 pm. Similarly, Blomberg  found that 68 patients (52.3%) sustained their injury between 3.00 pm and 11.00 pm and 38 patients (29.2%) were injured between 11.00 pm and 7.00 am. Our results are in line with the above-mentioned observations, as we also observed a continuous increase in the evening with a peak around 8.00 pm. However, most of the injuries in our study occurred during night (8.00 pm to 7.59 am) affecting primarily young adults. Given this pronounced peak during the night, an e-scooter ban at night might substantially decrease the number of injuries and should therefore be taken into account. Alternatively, advanced built-in lighting technologies to enhance the visibility of e-scooter riders could lead to a reduction of e-scooter-associated accidents during nighttime.
Moreover, seven patients self-reported to be riding the e-scooter under the influence of alcohol at the time of the injury. All seven patients sustained major head injuries, including one patient with an additional major injury of the upper extremity. Thus, e-scooter riders under the influence of alcohol had a significantly higher risk of sustaining major injuries (P = 0.001). Given the fact that these seven patients were injured during the nighttime, a possible night ban for e-scooters could likewise reduce the number of injuries sustained under the influence of alcohol.