The application of the WSES classification system for open pelvic fractures—validation and supplement from a nationwide data bank

International validation of the WSES classification for open pelvic fracture patients

Bony structure instability and internal hemorrhage can mostly be conservatively managed in closed pelvic fracture patients; however, the management of patients with open pelvic fractures can be challenging and requires a multidisciplinary approach. In addition to stopping concomitant external and internal hemorrhage, the difficulty of open pelvic fracture treatment includes the management of severe wound infection and further sepsis and multiple organ failure [11, 24]. The WSES guidelines suggest that the management of pelvic trauma must consider physiological and mechanical derangement [17, 19]. An international validation using the National Trauma Data Bank proved that the WSES guidelines were an accurate and reproducible classification system for pelvic injuries [18]. However, for open pelvic fractures, which are more dangerous than closed fractures, it is important to evaluate whether the WSES guidelines are still accurate and applicable.

In the current study, the accuracy of the WSES classification system for evaluating mortality in open pelvic fracture patients was validated by using the NTDB. The mortality rates associated with minor injury, moderate injury and severe injury were 3.5%, 11.2% and 23.8%, respectively. The odds of mortality also increased significantly from minor injury to severe injury (Fig. 1 and Table 1). Moreover, after excluding mortality patients, the hospital LOS also increased significantly as the class of injury increased from minor injury to severe injury in open pelvic injury patients. (Most patients with severe injuries may die within a few days because of uncontrolled hemorrhage or other associated injuries. Therefore, it is unfair to evaluate the LOS using all studied patients with both survivors and nonsurvivors.) Although there are differences between open and closed pelvic fractures, this nationwide study showed that the WSES guidelines still serve as a good evaluation modality.

The role of sepsis in open pelvic fractures and the WSES classification system

In addition to controlling hemorrhage, another challenge in the management of open pelvic fractures is the treatment of wound infection and further sepsis [25, 26]. A previous study reported that 21.4% of open pelvic fracture patients had colorectal injuries and 14.3% of patients had genitourinary system injuries [5]. Associated anorectal or urogenital injuries, contaminated soft tissue injuries and wound-related infection may lead to several complications, such as septicemia, coagulopathy, multiple organ dysfunction, hypotension and mortality [24]. The management of open pelvic fracture infection includes broad-spectrum antibiotics for both gram-positive and gram-negative bacteria, surgical debridement with presacral and perianal drainage and early colostomy for stool diversion [9, 27,28,29].

Therefore, we recognize that the evaluation of outcomes of open pelvic fracture cannot be limited to the status of hemorrhage or hemostasis, but infection and sepsis should also be considered. In 1997, the Jones–Powell classification system was developed to evaluate the morbidity and mortality of patients with open pelvic fracture [28]. In addition to mechanical stability, the concept of rectal injury evaluation and early diverting colostomy for infection control was considered in the classification system. However, this classification system was developed based on only a small number of patients (N = 39). A subsequent multicenter study that validated the Jones–Powell classification system in 2013 only had 64 patients [30]. Herein, many patients with open pelvic fractures in a nationwide databank were studied. Among all classes of injury severity, the mortality rates of patients with sepsis were significantly higher than those of patients without sepsis (Fig. 2). Furthermore, the proportion of sepsis in nonsurvivors was significantly higher than that in survivors (15.7% vs. 1.6%, p < 0.001). The subsequent MLR showed that sepsis served as an independent factor for the mortality of open pelvic fracture patients after adjusting for the WSES classification (Table 3).

The ROC curve showed an acceptable discrimination of the WSES classification alone for evaluating the mortality of open pelvic fracture patients (AUC = 0.717). However, an improved discrimination with an increased AUC was observed using the WSES classification plus sepsis (AUC = 0.767). In other words, sepsis plays an important role in the mortality of open pelvic fractures. Hence, the evaluation of sepsis is recommended as a supplement to the WSES classification for open pelvic fracture, which is associated with soft tissue injury and wound infection.

The association between hemorrhage and sepsis in patients with open pelvic fractures

It has been suggested that the cause of death among open pelvic fracture patients could be classified as death related to hemorrhage or associated injuries and death related to sepsis and further multiple organ failure [9, 11]. Uncontrolled hemorrhage-related mortality usually occurs within days of arrival at the emergency department because of the failure of hemostatic procedures (angioembolization or surgery). On the other hand, after the achievement of hemostasis, sepsis may occur and result in delayed mortality [1, 7]. In the current study, although most mortality (N = 50, 60.2%) occurred within 2 days, the mean LOS of mortality patients with sepsis was significantly longer than patients without sepsis (17.2 vs. 4.2 days, p < 0.001). The results of the current study supported that sepsis was related to late mortality. During the early stage of open pelvic fracture management, it is vital to achieve effective hemostasis, whereas sepsis control and the treatment of multiple organ failure may require efforts to prevent late mortality.

In patients with open pelvic fracture, the soft tissue injury from crush impact and hemorrhage from a hemostatic procedure may impair tissue perfusion, and the open contaminated wound may aggravate the infection condition. Previous reports that discussed the WSES guidelines for pelvic fractures suggested the evaluation of associated vascular injuries [17, 18]. The role of vascular injuries is more significant than the mechanical stability of the pelvis in the mortality associated with pelvic fractures. The current study found that the associated vascular injury increased the probability of sepsis in patients with open pelvic fractures. Therefore, concomitant vascular injury and sepsis may synergistically negatively affect each other in patients with open pelvic fractures.

Limitations of the current study

Previous studies of open pelvic fractures usually had small patient numbers [5, 7, 25, 28]. The advantage of the NTDB is its large number of relatively rare injuries; the significance of analyses could be augmented accordingly. However, the retrospective nature and possibly inaccurate records of the NTDB could limit the power of evidence. Furthermore, the definition of unstable hemodynamics in the current study was based on the vital signs upon emergency department arrival. The response to resuscitation could not be evaluated. Moreover, patients with open pelvic fractures are usually polytraumatized [2,3,4]. Patients with isolated open pelvic fractures were very rare. The associated injuries may affect the evaluation of mortality using the WSES classification system. Finally, the NTDB 2015, which is not an updated dataset, was used in the current study. However, the details of treatment that may be advanced in recent years were not discussed. We believe that the data from 2015 are applicable for an observational study only.

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