Despite significant advances in trauma surgery in the last few decades, the understanding of biomechanics and prediction of pelvic fracture stability remains controversial [8,12]. Even though Young & Burgess classification aids to comprehend the injury mechanisms and anticipate associated lesions, it is insufficient to accurately predict how these fractures behave under physiological loads. Previously, the AO based their classification on the direction in which instability of the pelvic ring was presumed; B2.1 and B2.2 fractures were considered rotationally unstable with maintained vertical stability; albeit also failing to accurately predict future displacement . Given the evidence available following the initial description of Pennal et al. and through the first decade of XXI century, LC-I fractures used to be managed nonoperatively . However, new evidence gave rise to question whether some of them would benefit from surgical fixation.
The wide spectrum of fracture severity, recoil phenomena, displacement and differences in clinical outcomes makes these a particularly difficult group of fractures to evaluate [8,9,15–17]. On the other hand, prediction of the dynamic behavior of these injuries with current static imaging methods, adds to the complexity of decision making. Dynamic stress testing under anesthesia is useful, but impractical to apply in all patients.
Displacement has been associated with poorer outcomes in pelvic fractures and the time needed to progress in physical rehabilitation has important physical and psychological consequences for these patients[18–22]. In 2018 the AO classification system incorporates the differentiation of stable and unstable lateral compression fractures primarily based on the severity of the posterior sacral fracture .
In this study we evaluated the rehabilitation milestones of TWI and TRW; consolidation and fracture displacement of non-operatively treated LC fractures, that under today's scope would be considered unstable.
An objective assessment of displacement in pelvic fractures is difficult. The complex three-dimensional anatomy and the impossibility of getting standardized comparable imaging in the trauma setting make the evaluation unreliable. In this study we conducted a subjective radiologic analysis relying on the ability of trained pelvic trauma surgeons to identify fracture displacement and consolidation. Only the unstable fracture patterns (group B) presented fracture displacement and delays in consolidation, though no significant differences between groups were observed. On the other hand, stable and unstable fractures presented significant differences in TWI and TRW. This suggests that the 2018 AO criteria helps to identify patients in whom a non operative approach results in prolonged rehabilitation periods, though whether the surgical treatment of these unstable fractures improves outcomes remains unclear [19,24–29].
This study has many limitations. The retrospective nature of the study doesn’t allow for functional scores or patient reported outcomes measure scores to be applied. The sample is small and composed entirely of workers entitled to compensation benefits which limits the external validation of the results.
This study adds to the growing evidence demonstrating variable outcomes in the highly heterogeneous LC-I fracture group. The revised 2018 AO classification system contributes in the identification of unstable fracture patterns that correlate with longer rehabilitation and work absentee times in which additional treatment strategies might be considered. Further studies should be conducted to determine the functional impact of surgery in these patients.