Kyle Forte, DO | EM/FM PGY3
The Article:
The Idea:
To explore the efficacy of diagnosing shoulder dislocation using a single view posterior approach point of care ultrasound (POCUS) and to determine a measured distance that helps to distinguish a normal versus dislocated shoulder.
The Study:
This was a prospective, observation study conducted in a single emergency department which aimed at using a single view POCUS for diagnosing shoulder dislocation. The study enrolled 84 adult (>18 years of age) patients who presented to the emergency department for acute, traumatic shoulder pain whom the treating physician ordered plain radiographs of the shoulder. POCUS was performed by novice sonographers who were blinded to the results of the radiographs. The novice sonographers used a single view posterior approach with the linear transducer placed transversely to look at the relative positioning of the glenoid fossa and the humeral head. Once structures were identified, horizontal lines were then placed tangent to the posterior aspect of the humeral head and the glenoid fossa. The distance between the two lines was measured (in cm) and was defined as the Glenohumeral Separation Distance (GhSD). The GhSD was given a positive or negative value based on the location of the glenoid rim relative to the humeral head. A positive GhSD indicated a posterior position of the glenoid rim relative to the humeral head and a negative GhSD indicated an anterior position of the glenoid rim relative to the humeral head. The GhSD was the primary measurement of interest and was used to correlate with the presence or absence of a shoulder dislocation seen with conventional radiography.
The Findings:
Of the 84 patients enrolled in the study 19 patients (22.6%) had radiography confirmed dislocations, all of which were anterior. Confirmed diagnosis of shoulder dislocations all had GhSD < 0 cm. Confirmed diagnosis of non dislocations all had GhSD > 0 cm. Based on this data a GhSD = 0 cm was chosen as cutoff value for diagnosis of anterior shoulder dislocation. Their derived POCUS demonstrated a 100% sensitivity, 100% specificity, PPV of 100% and NPV of 100% only in the diagnosis of anterior shoulder dislocations.
The Takeaway:
Overall this study demonstrated that even a novice sonographer can use a posterior transverse approach with POCUS to obtain a GhSD measurement to make a diagnosis of an anterior shoulder dislocation with high sensitivity and specificity. More research is needed to validate the GhSD measurement so a standard definition of sonographic shoulder dislocation can be established. If the measurement is validated, POCUS could help to reduce a potential delay in diagnosis and treatment. Further studies would be needed to determine if this measurement could be used to help prevent a delay in definitely treatment once shoulder reduction has taken place.