What characteristics indicate concomitant posterior pelvic injury in pubic ramus fractures in the elderly?

Background: Posterior pelvic ring injury (PPRI) can be challenging to diagnose and visualize using plain radiographs; sometimes, PPRI is even overlooked. This study aimed to investigate differences between isolated pubic ramus fractures and fractures concomitant with PPRI in elderly patients.
Hypothesis: Elderly patients with pubic ramus fractures and concomitant PPRI present different characteristics than patients with isolated ramus fractures.
Patients and Methods: We retrospectively reviewed data of 65 patients aged≥65 who visited the emergency department with a pubic ramus fracture on plain radiograph between January 2013 and December 2018. Patients were divided into two groups based on whether PPRI was found by computed tomography (CT). We then compared patient data and fracture characteristics between the two groups, including displacement and location of the pubic ramus fracture and presence of complete anterior pelvic ring disruption (i.e., concurrent superior and inferior rami fracture).
Results: PPRI was identified in 49 of 65 patients (75%) on CT. There was greater displacement of the pubic ramus fracture in patients with concomitant PPRI than in those with isolated pubic ramus fractures (4.6mm and 2.2mm, respectively, p<0.001). PPRI more commonly accompanied ramus fractures located medially to the obturator foramen than ramus fractures located in the obturator foramen or laterally to the obturator foramen (96%, 52%, and 77%, respectively, p=0.001). Complete anterior pelvic ring disruption was associated with significantly more concomitant PPRI relative to incomplete anterior pelvic ring disruption (84% and 22%, respectively, p<0.001).
Discussion: When a pubic ramus fracture is markedly displaced, located medially to the obturator foramen and complete anterior pelvic ring disruption, care should be taken to assess PPRI.
Level of Evidence: IV, retrospective study.
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