title: Pilot Study to Determine Accuracy of Posterior Approach Ultrasound for Shoulder Dislocation by Novice Sonographers.
abstract: BACKGROUND
  The goal of this study was to investigate the efficacy of diagnosing shoulder dislocation using a single-view, posterior approach point-of-care ultrasound (POCUS) performed by undergraduate research students, and to establish the range of measured distance that discriminates dislocated shoulder from normal.
  
  
  METHODS
  We enrolled a prospective, convenience sample of adult patients presenting to the emergency department with acute shoulder pain following injury. Patients underwent ultrasonographic evaluation of possible shoulder dislocation comprising a single transverse view of the posterior shoulder and assessment of the relative positioning of the glenoid fossa and the humeral head. The sonographic measurement of the distance between these two anatomic structures was termed the Glenohumeral Separation Distance (GhSD). A positive GhSD represented a posterior position of the glenoid rim relative to the humeral head and a negative GhSD value represented an anterior position of the glenoid rim relative to the humeral head. We compared ultrasound (US) findings to conventional radiography to determine the optimum GhSD cutoff for the diagnosis of shoulder dislocation. Sensitivity, specificity, positive predictive value, and negative predictive value of the derived US method were calculated.
  
  
  RESULTS
  A total of 84 patients were enrolled and 19 (22.6%) demonstrated shoulder dislocation on conventional radiography, all of which were anterior. All confirmed dislocations had a negative measurement of the GhSD, while all patients with normal anatomic position had GhSD>0. This value represents an optimum GhSD cutoff of 0 for the diagnosis of (anterior) shoulder dislocation. This method demonstrated a sensitivity of 100% (95% CI [82.4-100]), specificity of 100% (95% CI [94.5-100]), positive predictive value of 100% (95% CI [82.4-100]), and negative predictive value of 100% (95% CI [94.5-100]).
  
  
  CONCLUSIONS
  Our study suggests that a single, posterior-approach POCUS can diagnose anterior shoulder dislocation, and that this method can be employed by novice ultrasonographers, such as non-medical trainees, after a brief educational session. Further validation studies are necessary to confirm these findings.
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Shadi
authors.initials: S
authors.lastname: Lahham
authors.affiliation: Wellspan York Hospital, Department of Emergency Medicine, York, Pennsylvania.
authors.forename: Brent
authors.initials: B
authors.lastname: Becker
authors.affiliation: Olive View-UCLA Medical Center, Department of Emergency Medicine, Los Angeles, California.
authors.forename: Alan
authors.initials: A
authors.lastname: Chiem
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Joseph
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Craig L
authors.initials: CL
authors.lastname: Anderson
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Wilson
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Subeh
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Alex
authors.initials: A
authors.lastname: Trinh
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: Eric
authors.initials: E
authors.lastname: Viquez
authors.affiliation: University of California Irvine, Department of Emergency Medicine, Orange, California.
authors.forename: John C
authors.initials: JC
authors.lastname: Fox
mesh_terms: D000328:Adult; D000368:Aged; D002983:Clinical Competence / Q000592:standards*; D004504:Education, Medical, Undergraduate; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D008349:Manipulation, Orthopedic; D008875:Middle Aged; D010865:Pilot Projects; D019095:Point-of-Care Systems; D011446:Prospective Studies; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012783:Shoulder Dislocation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D020069:Shoulder Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013337:Students, Medical; D014463:Ultrasonography; D055815:Young Adult