Diagnostic accuracy of point-of-care ultrasound of the posterior fatpad in elbow fractures.

Background: Point-of-care ultrasound (POCUS) can potentially be used in the triage of patients with elbow injuries. However, the diagnostic accuracy of POCUS performed by non-radiologists for the exclusion of elbow fractures is yet unknown. This study aimed to investigate the diagnostic potential of POCUS of the posterior fatpad performed by non-radiologists in the workup of adult patients presenting with elbow injuries.

Methods: A multicentre, prospective cohort study was conducted between January 2021 and August 2022 in four EDs to determine the diagnostic accuracy of an elevated posterior fatpad on POCUS to demonstrate or exclude an elbow fracture in patients presenting with elbow injuries to the ED. The study population consisted of a convenience sample. In patients ≥16 years of age with an elbow injury for which an X-ray was ordered, POCUS was performed by emergency physicians trained in ultrasound. POCUS (index test) results were compared with X-ray outcomes (reference standard) to determine the diagnostic accuracy of POCUS.

Results: A total of 215 patients were included, 143 (67%) of whom had a fracture confirmed on X-ray. POCUS was positive based on a visualised elevated posterior fatpad in 127 (59%) patients. An elevated posterior fatpad on POCUS had a sensitivity of 91% (95% CIs 85% to 95%), a specificity of 93% (95% CI 85% to 98%), a negative likelihood ratio of 0.10 (95% CI 0.06 to 0.16) and a positive likelihood ratio of 13.09 (95% CI 5.61 to 30.54) for the presence of an elbow fracture. Post hoc review of the images by expert sonographers improved sensitivity to 96% (95% CI 91% to 99%).

Conclusion: POCUS of the posterior fatpad is a promising adjunct to physical examination to determine the need for further diagnostic studies in the triage of patients with elbow injuries. Sensitivity after a limited training is high, but not perfect, and can likely further be improved with additional training.