The current study is a large multicenter retrospective observational study that describes the epidemiology, clinical presentation, complications, and mortality in patients with pelvic fractures in two trauma centers. The first trauma center in the state of Qatar contributes to 64% of the data while the second center in Germany contributes to 36% of the data.
Pelvic fracture is not uncommon and is nearly reported in 10% (11% in Qatar and 13% in German) of admitted patients and tends to affect young subjects (mean 41 years old) in our cohort. Pelvic fracture caused by traffic-related injuries and falls suggested a high energy impact. In unstable cases, the frequent mechanism of injury was MVC followed by falls and pedestrian hit by vehicle.
Polytrauma is the norm in the present study, with an average ISS of 16. After excluding the extremities injuries, chest injuries outnumbered all other anatomical injuries in nearly 40% of cases in our cohort.
A high index of suspicion and prompt recognition of instability, both hemodynamic and fracture-related mechanical patterns, is of paramount importance in pelvic injuries.
The frequency of pelvic fracture in our cohort is relatively high, which represents the severe nature of trauma in young population, as it has reported in other countries like UK, Sweden, and Germany [16-18]. However, when comparing nationally based databases, there is variability in the prevalence and the affected age and gender worldwide [2,3,6,7, 16,17,18]. The German center data showed an older age and slight males predominance over females in comparison to the Qatar cases reflecting the country-based difference in the affected population .
Prior data advocated the crucial impact of age on the outcomes in trauma patients as advanced age alters the physiologic status resulting in a suboptimal recovery with higher chances for death and complications [19- 23]. However, in the current study, the mean age of patients was 41 years, a unique finding. It represents the national census of Qatar as the majority of population are young expatriate males . This may also explain the possible work-related injury pattern noticed in this cohort as well as the relatively better clinical outcomes in terms of inhospital complications rates and mortality. The majority of cases had high energy impacts due to traffic-related injury or falls. Studies have shown that high-energy impacts, particularly road traffic collisions and a pedestrian hit by vehicle, are the primary mechanisms of injuries leading to pelvic fracture [15,16,25,26]. Males are more likely to experience pelvic fractures, as they are more susceptible to these high energy mechanisms . Furthermore, falls are overrepresented as a leading cause of injury; this finding is exciting and can be explained by work-related falls as Qatar is undergoing a country-wide reconstruction surge in preparation for the WorldCup 2022.
In pelvic trauma, the hemodynamic instability on-admission predicts the requirement of massive blood transfusion, injury severity, associated injuries, fracture stability, in-hospital complications, and mortality [21,25,28-30]. However, A higher proportion of our patients was hemodynamically stable, admitted to regular trauma wards, and managed conservatively with lower rates of complications and mortality similar to data from the US and Europe. [6,16-18].
The reported mortality rates in pelvic fracture vary quite widely, which could be as high as 30% [12, 16, 21, 27] or even higher in cases with extensive soft tissue damage . In this cohort, the overall mortality was relatively low 4.7% that was correlated well with reported cases from previous studies in Germany (4%) and the US (3.5%) [18, 31].
This low mortality may reflect the maturation of the trauma system and improved post-traumatic care with the availability of specialized and multidisciplinary teams, massive transfusion protocol activation, immediate access to the operative room, and interventional radiology as well as subsequent advanced critical care. The basis in many of the contemporary published guidelines works group recommendations and performance improvement programs aim to improve the pelvic fracture outcomes [21,32-34].
The utility of shock index for early predicting significant hemorrhage and timely activation of the trauma team and massive transfusion protocol expedites appropriate care to stop the bleed and thereby improves clinical outcomes [7,35-37].
The present study showed higher mortality in unstable pelvic fracture patterns (i.e., Tile C; 13%) as compared to Tile A (3.2%) and B (4.7%). In hemodynamically stable patients, the mortality was 1.4% compared to 9.1% in unstable patients which is similar to the reported rate by Black et al. . The higher mortality in type B and C is contributed to the disruption of the posterior elements and higher rate of bleeding from the rich venous and vascular structures; in type B the disruption is partial which explains the smaller surge while in type C it is complete disruption [37,38]. Furthermore, previous German registry data showed a high incidence of complications in the form of sepsis in 5% and multiorgan dysfunction in 25% with a prolonged ICU length of stay .
Tile A classification of pelvic fracture is the most common type of pelvic fracture in the present cohort, which is similar to some of the studies that reported stable fractures as the most frequent fracture type . On the other hand, an earlier study from the Netherlands reported Tile B fractures to be predominantly followed by Tile C and Tile A fractures .
Agri et al.  reported that Tile C fractures were significantly associated with more blood transfusion and a higher rate of mortality as compared to Tile A or B fractures. Unstable pelvic fractures are the most severe skeletal injury due to its complexity, high-energy impact, and potential life threatening bleeding [43- 46]. Accurate and prompt assessment of patient injury, physiologic and anatomic classification and multidisciplinary management approach are essential components for effective management, improved outcomes, and future studies and audits.
Limitations: We acknowledge the limitations of our study. The retrospective study design and possible bias due to missing information or coding errors are among the most important limitations. Furthermore, The problem of comparability of different centers is another challenge that needs to be addressed. Moreover, trauma patients who died before hospital arrival were not included as well as those who were not admitted and discharged home. The higher frequency of significant associated injuries makes it impossible to separate the mortality caused by pelvic fracture per se effectively. The MTP activation documentation was not complete, so we used blood unit ≥10 for the identification of cases that had a massive transfusion. The place of injury was not documented in both centers, therefore we could not address the work-related injuries. We lack information for arterial embolization from the German institution. Also, our database is lacking results of functional outcomes and chronic sequel such as pain, impotence, disabilities. These missing pieces of information may urge the need to conduct further studies using isolated pelvic fractures only to determine pelvic fracture related-mortality and other underreported complications of this significant injury to strengthen our findings and to set the optimal time and type of management approaches for the new cases.
However, this is one of the largest databases available, the sample is somewhat homogenous with no wide age variation, and the Qatari center is the national center for trauma care in Qatar, so it is a national representing data. In contrast, the German center covers only 1.5 million populations within Germany.