Ample evidence exists on the relationship between bicycle injuries and craniofacial fractures. However, as the mechanism behind these injuries is often multifactorial, the presence of associated injuries (AIs) in this study population requires further examination. We hypothesized that patients with craniofacial fracture injured in bicycle accidents are at high risk of sustaining severe AIs, especially those of the head and neck region.
Patients and Methods
The investigators performed a retrospective study on all patients with bicycle-related craniofacial fracture admitted to a tertiary trauma centre during 2013 to 2018. The predictor variable was defined as any type of craniofacial fracture. The outcome variable was defined as any kind of AI. Other study variables included demographic and injury-related parameters. Variables were analyzed using bivariate and Firth's logistic regression analyses.
A total of 407 patients were included in the analysis. Our results revealed that AIs were present in 150 (36.9%) patients; there were multiple AIs in 47 cases. Traumatic brain injuries followed by upper limb injuries were the most frequent AIs. Severe head and neck injuries were present in 20.1% of all patients with craniofacial fracture. AIs were observed in 57.4% of patients with combined midfacial fractures ( P < .001). Helmet use had a protective effect against traumatic brain injuries ( P < .001).
Our results suggest that AIs are relatively common in this specific patient population. Close co-operation in multidisciplinary trauma centers allowing comprehensive evaluation and treatment can be recommended for patients with bicycle-related craniofacial fracture.
Bicycling is a popular, health-promoting, and environmentally friendly means of transport. Despite having many positive impacts, bicycling also exposes individuals to the risk of personal injury. This is partly due to the relatively high speeds compared with a somewhat low level of protection, often resulting in potentially severe injuries induced by high-energy transmission to both soft and hard tissues. In general, bicyclists are predisposed to injuries in all regions of the body. However, trauma to the head and neck region in particular may lead to long-term functional and neurological impairment.
A correlation between bicycle accidents and facial fractures has been documented, as facial injuries occur at a rate nearly identical to that of head injuries in patients sustaining bicycle-related trauma. In particular, the bones of the lower and middle third of the facial skeleton, areas not protected by standard protective helmets, are highly susceptible targets of energy transmission. In addition, a significant portion of this patient population sustains associated injuries (AIs). Of particular concern are the rates of concomitant severe head and neck injuries, such as traumatic brain, cervical spine, and blunt cerebrovascular injuries, in patients with bicycle-related craniofacial fracture.
The relationship between bicycle accidents and head injuries has been previously established and the use of safety helmets and other protective gear is widely promoted. The protective role of helmets in injured cyclists has been well documented, as previous studies have suggested that helmet use during bicycle accidents significantly reduces the odds of head injury. , , In addition to the design and shape of the protective helmet, compliance regarding helmet use, which strongly seems to be age- and gender-dependent, is an essential factor when assessing cycling-related head injuries. , , However, it is unclear whether helmet use has a protective effect on AIs and other traumatic brain injuries in the facial fracture population.
The aim of the present study was to clarify the occurrence and severity of AIs in patients with craniofacial fractures related to bicycle accidents. In particular, we sought to determine the risk of sustaining severe head and neck injuries in this patient population. We hypothesized that patients with craniofacial fracture injured in bicycle accidents are at high risk of sustaining severe AIs, especially those of the head and neck region.
This retrospective study was based on all patients admitted to a tertiary trauma center (Helsinki University Hospital, Helsinki, Finland) with any type of craniofacial fracture during 2013 to 2018. All patients with comprehensive patient files and any radiologically confirmed craniofacial fracture induced by a bicycle accident were included in the study.
The main outcome variable was any AI. These were categorized into traumatic brain injury (TBI), upper limb injury (including fractures and joint dislocations), thoracic and abdominal injury, cervical spine injury (CSI), blunt cerebrovascular injury (BCVI), ocular injury (injuries to the bulbus and optic nerve), pelvic ring injuries, and lower limb injury (including fractures and joint dislocations). Occurrence of AI types and patient mortality were reported.
The primary predictor variable was the type of craniofacial fracture (categorized as exclusively facial fracture, exclusively cranial fracture, and combination of both facial and cranial fracture). Additional predictor variables were the need for surgical intervention for craniofacial fractures and need for intubation on primary evaluation.
Additional analyses for specific cranial and facial fracture subtypes and AIs were performed. Isolated, unilateral zygomatic-maxillary and/or orbital fractures were grouped as zygomatic-maxillary-orbital fractures. Le Fort fractures and other different combinations of midfacial fractures were classified as combined midfacial fractures.
Explanatory variables included age, gender, specific injury mechanism, helmet use, and the influence of alcohol at the time of injury. Alcohol influence was verified from blood samples, by use of a breathalyzer, or history provided by the patient or paramedics. If alcohol influence could not be confirmed, these patients were classified as “No alcohol”.
In addition, associations between study variables and helmet use were analyzed separately, where patients with unknown helmet use status during the time of accident were excluded.
Pearson χ 2 tests or Fisher exact test were used as appropriate for categorical variables. The continuous variables were reported as means and standard deviations, as these were normally distributed. Firth's method of logistic regression was used for the univariate and multivariable analysis because of the low number of cases with 5 or less for craniofacial fracture injuries, which was the primary predictor variable. The variables retained in the multivariable model were based on a P -value <.2 because of the small sample size. Estimates were reported as odds ratios (ORs), with the statistical significance at 0.05 and 95% confidence intervals (CIs). The final model was found to have a good fit based on the Firthfit test. The variance inflation factor was used to test for multicollinearity. The variables in the final model each had a variance inflation factor <5 indicating minimal multicollinearity. Data analysis was performed using Stata version 16 (StataCorp, TX, USA).
The study was approved by the Internal Review Board of the Head and Neck Center, Helsinki University Hospital, Helsinki, Finland (HUS/356/2017 and HUS/54/2019).