Joint dislocations are common, and the shoulder is half of all joint dislocations. In the emergency department, we traditionally confirm the diagnosis on xray, reduce the shoulder (interscalene block anyone?), and then confirm reduction on post reduction xray films. The usual downsides of xray compared to ultrasound apply here - more time, more radiation, and having only a static image. Ultrasound potentially offers a way to diagnose shoulder dislocation, but how well does it perform in doing so?
How does POCUS compare with xray in diagnosing shoulder xray?
How does POCUS compare with xray in diagnosing fractures and verifying reduction?
Prospective, observational, convenience sample
2 hospitals, one academic
greater than 15 years old with suspected dislocation on exam
Only enrolled during shifts that attendings trained were working
younger than 15 (unclear what would happen if they arrived on their 15th birthday)
unstable vital signs
refused to consent
fracture diagnosis prior to POCUS
those in whom reduction was not accomplished
8 emergency physicians
Given special training for the study
30 min lecture
2 hours of practicing including diagnosing fracture in greater and lesser tubercles, humeral head, humeral neck, and glenoid rim. Also identifying hill sachs and bankart fractures.
Prospective convenience sample when any of 8 study physicians available
Study patients received POCUS of the shoulder prior to xray and then again after reduction attempt.
Probe choice: In this study a high frequency linear probe was used. You can also use a curvilinear probe.
Step 1: view shaft of humerus in short axis, posteriorly.
Step 2: slide up to find humeral head
Step 3: slide laterally to view GH joint and posterior glenoid labrum
Step 4: evaluate humeral head, tuberosities and intertubercular groove by sliding around anteriorly
98 (95.1%) had dislocation
POCUS for dislocation: 100% sens and 100% specific for dislocation
POCUS for fracture: 100% sensitive, 84.2% specific (only 9 fractures overall)
POCUS for reduction: 100% sensitive (*incorrectly reported in paper as 100% specific - because there were no negative xrays, there were no true negatives, can’t calculate specificity)
In this study, sonologists could not accurately determine anterior versus posterior dislocation.
High incidence of dislocation in this population
Extensive shoulder US use of study sonologists
If unsure if pathology present - instructed to rate as “pathology” --> likely attributed to high sensitivities
1. Ultrasound can be used to diagnose shoulder dislocation and reduction. In this study 100% sensitive and specific.
2. With training, ultrasound can also recognize shoulder fractures with high sensitivity.