The COVID-19 pandemic was a worldwide challenge for all societies and everybody’s personal life. Measures of social distancing, individual safety precautions and hygiene were proven to be effective means in prevention of viral spread in most countries worldwide [14]. Also, in Germany, depending on the incidence, strict lockdowns and social distancing were imposed in order to slow down the spread of the COVID-19 infection by home quarantines, residence regulations, nationwide and regional curfews, cancellation of community events and the restriction of local and long-distance public transport. Elective health treatments have been temporarily suspended or postponed in favor of caring for affected patients and conserving human resources [15, 16].

During the COVID-19 pandemic maxillofacial trauma procedures in Germany declined by 10.7%. This applies equally to the years 2020 and 2021, between which the number of interventions fell only slightly by 2.8% which might be a consequence of the pandemic wave and their associated measures that only began in the course of 2020 and the longer lasting second lockdown in the first 4 months of 2021. The median annual number of inpatient facial injury associated diagnoses, including patients with conservative and soft tissue injury inpatient treatment, decreased by 19.7% during the pandemic. As a shift in conservative and soft tissue injury treatment from the inpatient to the outpatient sector is likely within the situation of scarce medical resources in the pandemic and the number of facial injury associated diagnoses is not necessarily related to the severity of the injury or the number patients affected, this number has to be interpreted with caution when interpreted as a surrogate for the number of underlying traumatic events.

Our results were in accordance with other studies describing a decrease of maxillofacial fractures after the COVID-19 outbreak. Salzano et al. describe a decrease in maxillofacial fractures in an Italian multicenter study [17]. De Boutray et al. show a decreased incidence of maxillofacial trauma requiring surgery in a French multicenter study [18]. This is in accordance with the experience of multiple single center studies in different European countries [11, 19,20,21,22]. Also in the USA and Australia a decrease in facial fractures was reported in single center evaluations [23,24,25,26,27], despite there also being studies in the USA suggesting no significant change in facial trauma incidence, maybe due to a less restrictive policy of social distancing after initial lockdown compared to European countries [28, 29]. In Asian and Middle Eastern countries, specifically in India, South Korea and Jordan a decline in maxillofacial trauma surgeries was also described [30,31,32,33]. Non-maxillofacial fractures like ankle, hip or distal radius fractures were described to show a reduced incidence as well [34,35,36]. Reduced trauma associated admissions to primary care centers is a worldwide known phenomenon [37, 38]. Regarding the different anatomical regions, the largest decreases were seen for lateral midfacial fractures, orbital fractures and frontal sinus fractures. In contrast, the decline of mandibular fractures was more moderate. This could be a consequence of the different etiological factors influenced by the COVID-19 pandemic, especially concerning interpersonal violence and traffic accidents, which are also influenced by geographic location, population density, economic status, and cultural differences [3]. The regional analysis of the data shows that the decline in facial fractures is a nationwide effect that is not restricted to just a few cities, regions or centers. The lack of correlation to the cumulative regional COVID-19 incidence shows that the reduction in facial fractures is not due to the regional infection load but rather to the measures taken and their social effects.

Interpersonal violence was found to be the main cause of fractures in both the mandibular and midface regions especially among young men [3, 39]. In our data the decline of fractures in young male adolescents and adults between 15 and 34 years is representing more than 50% of the overall decline of maxillofacial fracture procedures. This may indicate that during the COVID-19 pandemic 2020–2021 the reduction of interpersonal violence is one of the main reasons for the reduced incidence of maxillofacial fractures. This thesis is also supported by the rather moderate, non-significant decline of fracture reductions in women for whom physical violence is not the most prominent cause of facial fractures. This also explains a significant shift to a more balanced gender ratio [3, 39]. Several single- and multicenter studies from different countries like Australia, Finland, India and the UK show a reduction in interpersonal violence associated facial fractures and injuries while the pandemic [25, 27, 40,41,42]. Although there are some studies describing a higher proportion of interpersonal violence in the incidence of facial injuries in France, Italy and the USA [18, 22, 23].

As road traffic accidents are the second most common cause of facial fractures the decline in road traffic accidents involving personal injury to a historic minimum is a second mechanism explaining a decline in facial fractures in Germany [43]. This is supported by data from France, Italy, Jordan and India [18, 19, 22, 33, 40, 42].

The restriction of social and societal life naturally also has an impact on private and professional contacts and could explain a decrease in facial fractures due to sports injuries and work accidents as other important causes of fractures [39, 44]. This was also described in studies from Australia, France and South Korea [18, 25, 32].

In elder people, falls are the most common cause of facial fractures, which are insignificant in other age groups [39]. The significant increase in facial fractures in the age group of 80 years and more (+ 23.5%, p < 0.05) and the increase in the average age suggests a significant increase in falls, possibly as a result of social distancing, social isolation and lack of social support of older people in the context of the COVID-19 outbreak. This is consistent with results describing the negative effect of social distancing on the physical and mental health of older people during the pandemic [45]. A pandemic-associated increase in facial injuries caused by falls is described in several publications from Australia, UK, India and Italy [17, 19, 20, 25, 27, 40, 42].

This study is subject to certain limitations, which are mainly related to the dataset that was available for analysis. First, the specific reimbursed OPS codes only represent fractures treated by open reduction and internal fixation in the analyzed years. Fractures treated non-surgically are not included in the dataset. Second, the study only includes trauma cases performed during a hospital admission that led to the billing of a DRG. Patients treated as outpatients or who use other reimbursement schemes could not be included. As reimbursement of trauma cases for hospitals in the DRG system covers more than 90% of the German population, we believe, however, that the dataset covers the vast majority of treatments. Another limitation is the completeness of the dataset itself, which provides information at only an aggregated level and in limited detail without information about a specific cause or severity of the injury; therefore, a more advanced analysis including anamnestic and diagnostic information was not possible in this scale using reimbursement data. This would, however, be interesting to evaluate further the impact of the COVID-19 pandemic on maxillofacial trauma care in detail.

To the best of our knowledge, this study is the first to examine the influence of the COVID-19 pandemic on the incidence and distribution of facial fractures at a national level in Germany. It can contribute to an analysis of the influence of legislative and personal measures to combat the pandemic on the associated shift in the genesis of facial fractures. The description of positive and negative effects can contribute to the future addressing of risk groups both during and outside of pandemic situations. For this purpose, the investigation of the direct influence of the measures on the causes of facial fractures should be expanded.