MSK Ultrasound for Shoulder Dislocation

October 2, 2020

Written by Alex Chen

Spoon Feed
This posterior ultrasound (US) approach to identify shoulder dislocation had 100% sensitivity and specificity for shoulder dislocation and was faster than x-ray by 43 minutes. However, the 92% sensitivity (with a lower 95% CI of 60%) for identifying non-Hill-Sachs/Bankart fracture makes me cautious about completely adopting POCUS until larger studies are done.

Why does this matter?
Shoulder dislocation is a common presentation to the ED. It can range from an easy reduction to one that requires procedural sedation and a great deal of your time and energy. Getting a patient to and from x-ray and coordinating resources can be a pain, and this study seeks to provide an easier and more expeditious way for you to diagnose and manage a shoulder dislocation.

“Let me see you bounce right to left and let your shoulder lean.” – Young Dro regarding posterior shoulder ultrasounds.
This was a multicenter prospective observational study with 65 total patients enrolled. Patients were enrolled if they were ≥18yo and had a suspicion of shoulder dislocation. All POCUS exams were done by US fellowship trained/in-training faculty. Sensitivity of posterior shoulder US for identifying shoulder dislocation was 100% (95% CI 87-100) and specificity was 100% (95% CI 87-100). POCUS improved time to performance of imaging by a median of 43 minutes (IQR 23-60) and took a median time of 19 seconds to perform.

Of the 65 patients, there were 25 (38%) fractures identified on radiography. POCUS identified 13/25 (52%) of the fractures. Of the 12 missed, only one was a non-Hill-Sachs/Bankart fracture (fracture of the surgical neck of the humerus). The sensitivity of POCUS for identifying non-Hill-Sachs/Bankart fracture was 92% (95% CI 60-99.6) and the specificity was 100% (95%CI 92-100). While this was only one patient in this study, this could lead to significant morbidity. While a Hill-Sachs or Bankart lesion does not alter our acute management of the shoulder dislocation in the ED, it does play into the follow-up, future risk of dislocation, and morbidity in these patients. The authors admit that this view does not provide a sufficient view of the glenoid and limits the diagnosis of these lesions. For me, I will likely be implementing this to gauge post-reduction success or in patients with recurrent shoulder dislocation without any trauma (low risk of fracture). Please see the following images copied from the paper for the ultrasound method.

Source
Musculoskeletal Ultrasonography to Diagnose Dislocated Shoulders: A Prospective Cohort. Ann Emerg Med. 2020 Aug;76(2):119-128. doi: 10.1016/j.annemergmed.2020.01.008. Epub 2020 Feb 25.

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