One of the main findings for this comparison of operative and non-operative treatment in lateral compression fractures of the pelvis was that we could determine the factors displacement, injury severity and age as crucial for decision-making. Although both groups varied a lot, there was no difference between the short-term outcomes in-hospital mortality and complication rate. Within this small cohort, only the injury severity was identified as an independent risk factor for mortality. For comparison of long-term follow-up, Merle D’Aubigne and EQ. 5D-3 L scores were evaluated in a matched subgroup, showing no difference between the treatment groups.
This data would indicate that neither short-term nor long-term results can be improved by surgical stabilization of type B2 fractures of the pelvis. However, this conclusion has a couple of limitations. Patients with injury characteristics usually requiring an operation such as disruption of the symphysis and complex injuries, including open fractures and injuries of internal organs, were excluded. Furthermore, the cohort represents only single-center data with a small number of patients. Despite, this is in accordance with other studies, which found no evidence that surgical stabilization of certain LC1 and LC2 pelvic fractures improved patients’ pain, decreased their use of analgesics, or improved time to mobilization [
15]. All these factors are considered to be decisive for mobilization [
14,
28]; and early physiotherapy is associated with less potential deadly complications. When looking a bit closer on the presented data for mortality, it becomes obvious that the rate ranges at the lower part of the expected interval, reflecting a rather stable injury and the exclusion of typically endangered patients. The mentioned bias of small numbers may be enhanced by this selection. Moreover, the relative frequency of dead was rather high in the conservatively treated group. A hidden possible positive effect of operative stabilization could be suspected as recently described in a much larger cohort [
9], which, however, focused on both B- and C-type fractures. The only identified independent risk factor for mortality in this cohort of B2 fractures was injury severity, which is in line with previous publications on pelvic fractures in general [
29‐
31]. Although we could identify parameters influencing decision-making for therapy, the presented data cannot answer, who should be operated, however, they are hypothesis generating. Why could it make sense to operate patients with a high ISS? They have other injuries besides a pelvic fracture, which is a problem with mobilization, especially when partial weight bearing is required. Fixation in this context provides more stability, resulting in less pain and increasing safety to prevent secondary displacement. To include maximal displacement of the posterior fracture component was proposed by several authors, suggesting that 5 mm might serve as a threshold for operative treatment [
27]. Apparently, the degree of displacement somehow influences decision-making, however, no clear cut-off value could be identified. In contrast, considering the percentile analysis, there is a large overlap between operatively and conservatively treated patients. This can be explained by various reasons. The relevance is dependent on the location, where the displacement is measured. If the fracture is not complete, the significance is probably limited. Furthermore, CT scanning is only a snap-shot, giving no further information about the ligaments and the periosteum, which might be intact considering the injury mechanism of a compression. Furthermore, age was identified as being decisive for the choice of therapy. With increasing age and osteoporosis, fractures occur more frequently following low energy trauma, which is associated with less displacement and a lower ISS [
32]. Therefore, this observation fits the conclusions made for the other criteria. A more pragmatic approach was recently suggested by Osterhoff et al., recommending operative stabilization only, if patients were not able to get mobilized [
33]. This can certainly be very helpful, however, it is also related to uncertainty, because it lacks clear guidelines. A possible solution to solve this dilemma could be the use of standardized protocols such as the de Morton Mobility Index (DEMMI) [
34] or the short physical performance battery (SPPB) [
35]. Considering the design of this study, which is based on a register, this parameter cannot be evaluated.
A limitation of the study is the registry-based approach, which allowed to use only the items primarily indicated in the database. Therefore, the fracture classification comprised only the systematics provided by AO/OTA and not by Young Burgess, which specifically addresses the problems associated with lateral compression-type injuries of the pelvic ring. This applies also to the component of the anterior pelvic ring. Here, only the nature of the pelvic ramus fractures could be analyzed but not the actual displacement. However, it was a consensus decision of the steering committee to skip the absolute distances because of lacking relevance. Moreover, the mechanism of injury was not documented. The follow-up included only 19 patients, which might not be representative for the whole population. This was caused by the fact that most patients did not match the criteria for pairing. Furthermore, some patients were simply not available for follow-up.