Intended for healthcare professionals

Rapid response to:

Endgames Spot Diagnosis

A painful shoulder after a seizure

BMJ 2019; 366 doi: https://doi.org/10.1136/bmj.l4511 (Published 08 August 2019) Cite this as: BMJ 2019;366:l4511

Rapid Response:

Why the lateral view is dangerous - Response to Spot Diagnosis: A painful shoulder after a seizure

Dear Editors,

We read our colleagues’ spot diagnosis article with great interest as well as the rapid response by our Australian colleague. Further to his response we wished to submit our own comments.

The article recommends a lateral or modified axillary view to aid diagnosis of posterior shoulder dislocations, however we conducted a large-scale review of missed posterior dislocations at a major trauma centre in London and found that a lateral view is of far inferior diagnostic benefit compared with a modified axial view and can even be falsely reassuring. Our findings, as well as an extensive literature review, led us to recommend the anteroposterior (AP) and modified axillary view only. This recommendation is supported by a previous retrospective review (Neep MJ et al. 2011), which found that almost 10% of examinations would have been incorrectly reported as normal if AP and lateral views were performed without a modified axial view and, furthermore, lateral views did not demonstrate anything which was not shown on modified axial views. We add that, in cases of diagnostic uncertainty, an urgent CT scan should be performed.

The authors go on to recommend immobilisation in a sling post reduction. While they do not clarify, it would be sensible to assume they mean a simple broad arm sling. This is not appropriate in the case of a posterior dislocation, as the internal rotation of the shoulder in such a sling is a position of instability and often leads to recurrent dislocation. To avoid this, the shoulder should be maintained in either a neutral or externally rotated position with an appropriate brace. On a related note, the ‘lightbulb sign’ on an AP view is no longer considered pathognomonic of posterior dislocation because, when a standard sling is applied at initial presentation, this internally rotated position is often radiologically indistinguishable from that associated with posterior dislocation resembling a lightbulb.

Our review of the radiological diagnosis of posterior shoulder dislocations as well as the specifics of an imaging protocol for shoulder trauma which we have introduced at our institution is currently under review for publication with BMJ Open Quality. Should you wish for further details we would be happy to provide them.

Yours Sincerely

Competing interests: No competing interests

10 September 2019
Alex P Magnussen
Specialist Registrar Trauma and Orthopaedics
Dr C Watura, SpR Radiology; Dr M Walker, Consultant MSK Radiologist, Imperial College NHS Trust; Dr D Amiras, Consultant MSK Radiologist, Imperial College NHS Trust; Mr D Griffiths, Consultant Orthopaedic Surgeon, Imperial College NHS Trust
Imperial College NHS Healthcare Trust
75 Bloomsbury CLose, London, W53SF