Images and Case Report by Dr. Stephen Meigher
A twenty-something, skinny, athletic-built male presents to your ED complaining, “I dislocated my shoulder.” He has no other past medical or surgical history and is a minimal historian who states he dislocated his shoulder “10 years ago playing basketball” and just did it again “reaching down to the ground for my phone.”
The reported mechanism is suspect, but he sits on your stretcher rocking and moaning in pain as he hold his left shoulder, obviously boxed, with his right hand. He guards against any movement and manipulation of the shoulder, including gentle undressing and at first refuses x-ray as he is scared he has to move that arm for the picture.
The curvilinear probe solves all your woes. A lesser used function, but rising in versatility, the musculoskeletal sonogram offers quick and simple answers to questions of dislocation and fractures.
Technique: The ultrasound probe is placed ipsilateral to the injury, screen facing the patient as you stand directly behind him watching. The curvilinear probe is placed transverse, just inferolateral and parallel to scapular spine. The probe marker faces midline and the probe gradually translated laterally until just rounding the posterior curve of the shoulder, stopping at the posterior axillary line.
The image seen fits the clinical impression. An identifiable humeral head is seen deep (further from the posterior probe, and thus, anterior to the glenoid fossa). You are reassured that your gestalt diagnosis is correct and you sonogram that contralateral, normal, right shoulder to convince yourself while awaiting the plain films.
Your ultrasound diagnosing anterior dislocation of the left shoulder is verified by the below Y-View of the left shoulder and moreover, it confirms the anatomic pocket for intra-articular block made by the dislocation deficit. The left shoulder is sterilized, an 18-guage needle introduced through the same defect and joint fluid aspirated before 10 cc of 1% lidocaine is injected into the joint space. Manual reduction is attempted without complication and successful on its third attempt.
The same sonogram is repeated and much to your delight, the left shoulder mirrors the right with articulation of both the glenoid and humeral head. The patient is placed in a sling with his left arm abducted, internally rotated, and flexed at the elbow. A post-reduction film confirms the same and the patient is discharged with 2-week orthopedics follow-up, care instructions, and return precautions.
Teaching Points
- POCUS can be used quickly and easily to diagnose anterior or posterior shoulder dislocations when suspected
- With the probe directed posterior to anterior, an anterior dislocation corresponds with a deep deficit of the humeral head while a posterior dislocation corresponds with a shallow displacement of the humeral head
- POCUS of a shoulder dislocation offers a quick segue to intra-articular block for reduction because it shows the deformity and articular pocket to direct a sterile needle
- Ultrasound can be used throughout and following reduction attempts to quickly gauge proper replacement of the humeral head into the glenoid fossa
- A small prospective observational study has found ED Physician POCUS for shoulder dislocation to match the fidelity of plain films in diagnosis with equal sensitivities of 100%
References
1. Riguzzi C, Mantuani D, Nagdev A. How to Use Point-of-Care Ultrasound to Identify Shoulder Dislocation. ACEP Now. 2014; 38(8). https://www.acepnow.com/article/use-point-care-ultrasound- identify-shoulder-dislocation/ Accessed August 30th, 2019 Abbasi, Saeed et al.
2. Diagnostic Accuracy of Ultrasonographic Examination in the Management of Shoulder Dislocation in the Emergency Department. Annals of Emergency Medicine, Volume 62, Issue 2, 170 – 175 Blakeley CJ, Spencer O, Newman-Saunders T, et al
3. A novel use of portable ultrasound in the management of shoulder dislocation, Emergency Medicine Journal 2009;26:662-663. Beck, Sierra et al.
4. Point-of-care ultrasound diagnosis and treatment of posterior shoulder dislocation. The American Journal of Emergency Medicine, Volume 31, Issue 2, 449.e3 – 449.e5