Standard practice in the treatment of unstable pelvic ring injuries: an international survey

Purpose Unstable pelvic ring injury can result in a life-threatening situation and lead to long-term disability. Established classification systems, recently emerged resuscitative and treatment options as well as techniques, have facilitated expansion in how these injuries can be studied and managed. This study aims to access practice variation in the management of unstable pelvic injuries around the globe. Methods A standardized questionnaire including 15 questions was developed by experts from the SICOT trauma committee (Société Internationale de Chirurgie Orthopédique et de Traumatologie) and then distributed among members. The survey was conducted online for one month in 2022 with 358 trauma surgeons, encompassing responses from 80 countries (experience > 5 years = 79%). Topics in the questionnaire included surgical and interventional treatment strategies, classification, staging/reconstruction procedures, and preoperative imaging. Answer options for treatment strategies were ranked on a 4-point rating scale with following options: (1) always (A), (2) often (O), (3) seldom (S), and (4) never (N). Stratification was performed according to geographic regions (continents). Results The Young and Burgess (52%) and Tile/AO (47%) classification systems were commonly used. Preoperative three-dimensional (3D) computed tomography (CT) scans were utilized by 93% of respondents. Rescue screws (RS), C-clamps (CC), angioembolization (AE), and pelvic packing (PP) were observed to be rarely implemented in practice (A + O: RS = 24%, CC = 25%, AE = 21%, PP = 25%). External fixation was the most common method temporized fixation (A + O = 71%). Percutaneous screw fixation was the most common definitive fixation technique (A + O = 57%). In contrast, 3D navigation techniques were rarely utilized (A + O = 15%). Most standards in treatment of unstable pelvic ring injuries are implemented equally across the globe. The greatest differences were observed in augmented techniques to bleeding control, such as angioembolization and REBOA, more commonly used in Europe (both), North America (both), and Oceania (only angioembolization). Conclusion The Young-Burgess and Tile/AO classifications are used approximately equally across the world. Initial non-invasive stabilization with binders and temporary external fixation are commonly utilized, while specific haemorrhage control techniques such as pelvic packing and angioembolization are rarely and REBOA almost never considered. The substantial regional differences’ impact on outcomes needs to be further explored.


Introduction
Unstable pelvic ring injuries represent a challenging injury for trauma surgeons. Established classification systems, imaging, resuscitative methods, implant options, and surgical techniques have allowed for an improved understanding, stabilization, and treatment of these injuries [1][2][3].
Unstable pelvic ring according to Young and Burgess which is based on the injury mechanism is defined as anterior poster compression (APC) type II/III, lateral compression (LC) type III, vertical shear (VS), and combined mechanism (CM) [4,5]. Using the AO/Tile classification which relies on vertically and rotational stability, type B (partially unstable) and C (completely unstable) are indicative of an unstable pelvic ring situation [6]. The terminology of an unstable pelvic ring is used due to the concomitant disruption of major ligaments and injuries to the soft tissue and internal organs as well as venous or arterial bleeding in these fracture patterns [7]. This constellation of injuries can result in substantial haemodynamic instability with possible exsanguination and death [8,9].
Overall, the incidence of operations of the pelvic ring is drastically rising within the last years, whereas especially the usage of minimally invasive procedures with screw fixation seems to have found its way into frequently used practice over the last decade [10]. Nowadays, percutaneous screw stabilization of the posterior pelvic ring is also performed in emergency situation ("antishock/rescue screws"), which provides an alternative to otherwise used techniques such as C-clamp application [11]. In addition, a recent survey among international trauma surgeons provides evidence that percutaneous might provoke a smaller surgical load (second hit phenomenon) in polytraumatized patients [12].
Yet even with potential long-term disability associated with these injuries, no standard treatment algorithm exists, and variability among treating surgeons remains [13]. Still, a recently published treatment algorithm treatment for unstable pelvic ring injuries highlights the relevance of the physiological status on the surgical decision-making and proposes fixation strategies according to the injury pattern [14]. Prior studies examining variability among surgeons have highlighted heterogeneity in most facets of the treatment of these injuries, including timing of definitive fixation, anatomic location of fixation, and treatment of haemodynamically unstable pelvic ring injuries [15][16][17]. This dearth of high-quality evidence may be the impetus for the substantial management variability associated with these fractures. Yet, within the current literature, there is no investigation into geographical variation of treatment for unstable pelvic ring injuries.
This study aims to evaluate similarities and differences in treatment strategies for unstable pelvic ring care among an international cohort of surgeons. To gain this knowledge, responses were collected from a standardized questionnaire completed by surgeons from an international trauma society representing a large collection of differing nations and geographic regions.

Study design
The initial survey was developed by the SICOT trauma committee and other experts of pelvic ring injuries.
Pilot study: The survey was preliminarily evaluated by experienced trauma surgeons (S.H, M.T R.P, H-C.P) and members of the SICOT trauma committee; annotations and suggestions were implemented.
The survey was then disseminated among members of SICOT, and responses were collected after voluntary participation and submission of survey responses.

Ethics approval statement
The survey was anonymous and voluntary. All participants agreed to the use of their provided data. The local ethic committee disclosed a general waiver for anonymous surveys.

Survey
The questionnaire was offered between September 05 and October 05, 2022, consisting of twelve possible selections between four different categories.
Sociodemographics: (Gender, country, working experience, level of education, and treatment frequency of unstable pelvic ring injuries); five questions.
The survey function in Google forms (Google LLC, "Standard practice in treatment of unstable pelvic ring injuries", Accessed 10/05/22, https:// forms. gle/ ajSqU CktVK aQi7g r8) was used by which anonymity was guaranteed to all participants. The online survey (Appendix 1) was distributed to the members of SICOT. One reminder was sent after four weeks to members of SICOT.

Statistical analysis
Categorical and ordinal variables are shown as count and percentages and continuous variables as mean, median, or mode (most frequent answer). Groups of continuous variables were compared with Student's t-test. Graphics were created utilizing the R-package ggplot (R Core Team (2019), R Foundation for Statistical Computing, Vienna, Austria (https:// www.R-proje ct. org). Statistical analysis was performed using R (R Core Team (2019), R Foundation for Statistical Computing, Vienna, Austria (https:// www.R-proje ct. org)) [18]. Stratification by continent was performed. A 4-point rating scale was chosen without a category such as "sometimes" in between "often" and "seldom" to avoid a central tendency, allowing for improved isolation of the actual treatment standards.

Participant's demographics
A total of 358 participants from 80 countries completed the questionnaire. Countries from Asia were most represented (n = 177, 50%), followed by African (n = 70, 19.8%) and European (n = 63, 17.8%) countries. Participants were mostly male (n = 331, 92.7%) and most commonly in consultant positions (n = 231, 64.5%), as well as head of department (n = 48, 13.4%) or fellows (n = 46, 12.8%). Experience was stated as > ten years in 48.3% (n = 173), 5-10 years in 30.4% (n = 109), and < five years in 21.2% (n = 76) of responses. The volume of treated unstable pelvic ring injuries was quantified as one to five per months for 66.5% of the participants (n = 238), whereas 13.1% (n = 47) reported treatment of five to ten unstable pelvic ring injuries per month. Additionally, 8.7% (n = 31) of participants stated to treat more than ten unstable pelvic ring injuries per month, and 11.7% (n = 42) participating surgeons indicated to not treat any. Summaries and additional demographic information can be seen in Table 1 and Appendix (Table 7).

Pelvic binders
The usage of pelvic binders or sheets showed high accordance among all participating surgeons with approximately 87% (n = 308) of responders stating they always or often used them in the prehospital setting (median and mode = often).
Mode and median of all individual participating surgeons from all continents were either "always" or "often". Relevant differences in usage were not apparent among continents (Table 3, Fig. 2).
Preoperative 3D-computed tomography scan (CT scan) 65.5% and 20.8% of participants reported that they always or often used 3D CT scans preoperatively. Within each continent, the mode of responses was "always performing a preoperative 3D CT scans". This was also observed with mean, with exception of the median from responses of surgeons in Africa, which was found to be often use of preoperative 3D CT scans (median = often) ( Table 3, Fig. 2).

External fixation
Among all participants, 51.5% stated often performing external fixation (19.9% = always, 23% = seldom; mode and median = often). No large differences were observed in regard to central tendency. Individuals from all continents stated they often performed external fixation (mode), except for South American respondents, which tended to report always performing external fixation (median = often-always, mode = always) ( Table 4, Fig. 3).

Rescue screw (acute percutaneous posterior pelvic ring stabilization) usage
Overall, 45.7% of respondents indicated never utilizing rescue screws and 30.3% reporting seldom use (median = seldom, mode = never). The only continent reaching a mode of "Seldom" was North America, whereas respondents from other continents most commonly answered "Never" using rescue screws, indicating a distinct lack of use outside of North America (Table 4, Fig. 3).

C-Clamp usage
C-Clamps were reported as rarely used, with 42.9% of all the participating trauma surgeons stated they never used C-clamps, while 33.3% stated seldom use (median and mode = never). The highest rate of use was observed among surgeons from Asia and Europe (median = seldom; mode Asia = seldom, mode Europe = never), whereas participants from other continents most commonly reported never using C-clamps, with calculated median and mode indicating "Never using c-clamps" ( Table 4, Fig. 3).

Pelvic packing
Pelvic packing for hemostasis was reported with a central tendency to seldom performed (47%), 28% of participants

REBOA usage
REBOA use was reportedly rare, with 67.7% of all participants stating no use and 24.7% reporting utilization (median and mode = never). Surgeons from Europe and North America indicated highest proportion of use (Europe: often = 15.9%, seldom = 39.7%; median = seldom, mode = never) (North America: often = 10%, seldom = 50%; median and Mode = seldom), whereas REBOA use by surgeons elsewhere in the world was most commonly reported as rare or never (median and mode = never) ( Table 5, Fig. 4).

Percutaneous techniques
Percutaneous techniques were reported as often used by 51.1% of respondents (median and mode = often). No substantial differences were observed among surgeons within different continents (median and mode = often; median Asia = seldom-often) ( Table 6, Fig. 5).

Navigated percutaneous techniques
Overall, navigated techniques were indicated as rarely utilized, with 65.4% having stated never using navigated techniques, and 19.5% reporting seldom use (median and mode = never). Surgeons from Oceania reported the highest use (median and mode = seldom), though with a small number of surgeons representing the region (n = 8) ( Table 6, Fig. 5).  Fig. 6).

Discussion
Pelvic ring injuries are associated with high-energy trauma, commonly involving multi-systems, requiring multi-disciplinary treatment and approach [8,19]. Early approximation or restoration of native pelvic anatomy reduces pelvic volume, facilitating improved intrapelvic clot formation and haemostasis [20,21].
Even with advancement in imaging and treatment modalities or techniques, along with improved resuscitative methods, broad international agreement in treatment of unstable pelvic ring injuries remains elusive. These fractures represent a challenge for trauma surgeons since they are associated with a high morbidity and mortality due to concomitant haemorrhage, shock, and coagulopathy [22].
Comparison and standardization of different treatment algorithms could potentially lead towards improved outcomes after these debilitating injuries. This study represents one of few studies examining international practice variation around the globe in regard to different facets of treatment for these injuries.

Study limitations
This expert opinion survey (evidence level IV) is limited to a certain degree. The questionnaire was provided to the entire SICOT society, but the demographic information of the ones not participating could not be retrieved. Therefore, it can only be assumed that the participating cohort is representative for the trauma society. Participants could only choose from and comment to predefined (treatment) options that are most common and determined by the authors. In addition, stratification was performed by continents, which implies homogenous practice in all the underlying countries. There is likely to have huge variability within practice in each continent, which is hidden in this survey. A more detailed (country-wise) analysis would not have been reasonable due to varying sample sizes.
Based on the results of this study: 1) The Young-Burgess and Tile/AO classifications are the most commonly used and in approximate equal proportion. 2) Initial stabilization with binders/sheet is commonly used worldwide. 3) Most surgeons report temporizing stabilization of the pelvic ring with an external fixator. 4) Haemostatic techniques such as pelvic packing and angioembolization are rarely used and REBOA almost never.
Our study participants reportedly use the Young-Burgess and Tile/AO classification systems equally without relevant geographic differences. The Tile/AO classification focuses primarily on posterior pelvic ring stability, whereas the YB classification emphasizes the trauma mechanisms. Prior studies have not established clinically relevant differences when comparing the classification systems in terms of mortality prediction and transfusion/infusion requirements [23]. Still, the interobserver reliability of both classification systems is frequently addressed in literature, whereas it seems that using the Young and Burgess classification provides a better agreement in between surgeons than the AO/Tile classification [24]. This suggests either classification could be used, predicated on consistence of use to improve observer reliability within the institution [24].
In this survey, majority of trauma surgeons, regardless of geographic location, indicated routine prehospital pelvic binder use. Application of a pelvic binder is widely accepted and has been associated with improved haemostasis and mortality reduction in patients with unstable pelvic ring fracture [25][26][27]. A recent study evaluated the influence of pelvic binder placement accuracy on the resuscitation requirements, whereas displacement of the binder always occurred cranially of the target structure (trochanteric region). No effect on resuscitation parameters or preclinical fluids was seen in this study [28]. Still, correct placement of the binder is of essential importance for the overall outcome [29]. We conclude that the pelvic binder is a simple and relatively benign procedure when applied correctly, with this study's findings suggesting its use is seemingly uniformly agreed upon.
Overall, the usage of computer tomography seems to increase the agreement, especially in terms of differentiation in between stable and unstable fractures [30]. Additionally, there was wide agreement in preoperative imaging modalities, with most surgeons indicating a 3D CT is obtained preoperatively, further substantiating reports from a recent survey study [17]. The use of 3D CT allows improved evaluation of fracture morphology/classification and characteristics, as well as concomitant injury identification, such as vascular or soft tissue injuries. Prior studies have suggested that obtaining CT scans was associated with better outcome in severely injured patients [31,32]. Yet, the overall infrastructure and localization of the computer tomography is from essential importance, whereas it needs to be performed quickly especially in haemodynamically unstable patients [33,34]. The findings in this study are in accordance with the establishment of 3D CT scans as a reliable and beneficial imaging modality, suggesting preoperative 3D CT scans have become a standard diagnostic method for patients with unstable pelvic ring injuries [35]. Unstable pelvic ring injuries often require emergent restoration and mechanical stabilization of pelvic ring anatomy, in part to reduce bleeding and pain in patients [36,37]. Our findings suggest that the pelvic ring is most commonly temporized with external fixation, with high accordance among surgeons who participated in this study. This is in line with recent literature reporting that surgeons tend to prefer supraacetabular pin placement over iliac pins in a damage control setting [17,37].
Temporal fixation with C-clamps was reported to be sparingly used, whereas a recent study reports a beneficial effect of C-clamp application on haemodynamically unstable patients in terms of the hemodynamic stabilization [38], and the high forces imparted with a C-clamp may increase risk of sacroiliac dislocation or over-compression [39]. This troublesome side effect profile has resulted in infrequent use. Gardner first described the usage of acute percutaneous posterior pelvic ring stabilization with "antishock iliosacral screws", which are also referred to as "rescue screws" [11,40]. However, this procedure requires substantial surgeon experience; mirrored by our findings, its use is predominated by those in high-volume centres. As such, the seemingly infrequent use of C-clamps and rescue screws might stem from these factors, and others, with unsurprising findings suggesting their use is sparse.
In the setting of persistent haemodynamic instability, further surgical interventions such as pelvic packing and/or angioembolization may be used to control pelvic bleeding [41][42][43][44]. Pelvic packing can be quickly performed within 30 min and aims to tamponade venous bleeding, which may also be performed in combination with external fixation [17,45]. Angioembolization, in general, requires more time and institutional resources [46]. Due to the immense personnel and equipment requirements, not all trauma centres have permanent angioembolization capabilities. It is of note, however, the two techniques are not mutually exclusive, and can be utilized in tandem, and are more likely to be used in high-volume trauma centers [42,47]. Prior studies have reported an association of angioembolization with reduction of mortality [48]. Yet, it has been discussed that this mortality reduction may be due, in part, to a requisite level of patient stability for patients to be amenable for angioembolization, as there may be increased time requirements for proper equipment and personal to perform the procedure. In contrast, patients who are too unstable to wait for angioembolization may require more expedient methods of hemostasis (e.g., pelvic packing) since angioembolization is usually performed in between two and four h [49]. Additionally, combination pelvic packing (primary) and angioembolization (secondary) has been suggested to be beneficial in patients without haemorrhage controlled primarily [50].
The use of REBOA showed a geographic skew. There was greater use in North America compared to other regions; possibly highlighting its use may require high resource institutions and more robust system processes [51]. In addition, lack of surgeon familiarity with its use, high mortality rates, and frequent  [52][53][54][55].
The timing of definitive reconstruction in patients with major fractures, such as a pelvic ring fractures, remains contested [56][57][58]. Early invasive surgery-especially in polytraumatized patients-may exaggerate immunologic and inflammatory responses provoking the "second hit" phenomena, possibly associated with adverse complications and outcomes [59,60]. In response to this consideration, surgeons may consider physiologic markers or "window of opportunity" when deciding on timing of surgery. A prior study surveying European-based surgeons reported high reliance on a patient'' physiologic status when determining timing of fracture fixation, rather than the "window of opportunity" when performing a secondary/staged reconstruction [61]. This study congruently aligned with those findings, with  Approaches by which staged/secondary surgery protocols are performed across the continents most surgeons identifying a patient's physiology as the main determinant in surgical timing. Yet, even with physiologic status and response of immense importance, a large number of responding surgeons indicated utilization of the "window of opportunity" for timing of fracture fixation. In contrast, some retrospective studies suggest a more dogmatic early definitive stabilization for unstable pelvic ring injuries regardless of the physiology, reporting favorable outcomes [62][63][64]. Yet, highquality evidence comparing various methods of determining timing of fracture fixation is lacking.
Recent publications have suggested using multiple parameters to identify when severely injured patient may be stable enough for secondary surgery [65]. Prior studies have incorporated evaluating multiple systems and parameters, such as acid-base balance, body temperature, coagulation, and tissue damage, to aid in improved prediction of early complications when compared to evaluating fewer or single parameters complications [66][67][68]. Moreover, repeated assessment of physiological parameters in patients with multi-systems injuries allows identification of patients who benefit from early fixation. Intuitively, minimally invasive surgical procedures such as percutaneous pelvic stabilization and navigation techniques allow for early fracture fixation without severely compromising the patient's physiology commonly associated with open orthopaedic procedures [69][70][71]. These concepts were exemplified in our study, with percutaneous techniques reported as commonly used.

Conclusion
This survey of orthopaedic trauma surgeons in regard to treatment of unstable pelvic ring injuries revealed some areas of accordance and discordance in practice. Most surgeons utilize pelvic binders/sheets as an augment to initial stabilization. Additionally, most surgeons report commonly temporizing stabilization of the pelvic ring with an external fixator. Emergency stabilization of the posterior pelvic ring with C-clamps or rescue screws is less commonly performed. Haemostatic techniques such as pelvic packing and angioembolization are infrequently utilized. There was a high degree of variability in regard to determining surgical timing of sequential surgeries, which seems to be a topic under discussion. Most respondents indicated utilizing minimally invasive surgical techniques for definitive fixation of unstable pelvic ring fractures. The current survey study, with international distribution, presents regional agreements and discordances in treatment variation of unstable pelvic ring injuries. Future efforts may include comparison and evaluation of established protocols and treatment algorithms between regions of the world.

Appendix 1
Survey Google forms "Standard practice in treatment of unstable pelvis ring injuries"