Self-Reduction in Proximal Humerus Fractures through Upright Patient Positioning: Is It up to Gravity?

Background: The self-reduction in proximal humerus fractures (PHFs) remains a poorly explored myth, and it was rarely investigated in the past. One of the oldest hypotheses suggests that gravity and the weight of the affected arm alone are driving forces, which facilitate a self-reducing potential in PHFs. However, thus far, clear radiographic evidence for this theory is missing in the literature. This study aimed to investigate the immediate effect of upright patient positioning on self-reducing of PHFs. Methods: Between November 2019 and November 2020, seven consecutively bedridden but mentally competent patients were admitted to our emergency department with an acute proximal humerus fracture. Within routinely attempts of closed reductions under the control of an image converter (C-arm), immobile patients were mobilized into an upright sitting position on a stretcher while the affected arm was immobilized in a sling. Fluoroscopic controls were performed before and after upright positioning. Changes in the head-shaft angle (HSA), as well as the medial hinge index (MHI), were determined on plain true anteroposterior (AP) fluoroscopic images. Results: In all cases, upright patient positioning had an immediate self-reducing effect. This effect could be seen in five out of seven cases for both HSA and MHI. Changes in HSA and MHI averaged 21.2° and 0.25, respectively. Mean deviation from an ideal, anatomic HSA of 135° decreased through upright positioning from 25.5° to 13.8°. Mean deviation from an ideal, anatomic MHI of 1 decreased through upright positioning from 0.28 to 0.19. Conclusions: Upright patient positioning might contribute immediately to the self-reduction in PHF through the force of gravity. This underlines the importance of being aware of patients’ position when interpreting X-ray images within treatment decision-making processes.