in or out ???

the case.

A 34 year old insulin-dependent diabetic male presents to your ED following a “collapse” stating he thinks he has had a seizure. He has had hypoglycaemic seizures previously. He lost his glucometer 3 or 4 weeks ago and has been guessing his sugars and corresponding insulin doses by ‘how he feels’…

He has severe bilateral shoulder & upper thoracic pain. Any attempt to move, touch or examine either shoulder results in unbearable pain (plus a stream of four-letter expletives).

As part of his evaluation you get the following x-rays….

   

[DDET Interpretation:]

• Bilateral humeral head/neck fractures
• Right glenoid fracture with drumstick appearance of humeral head.
• Left lesser tuberosity fragment.
• Both humeral heads appear posteriorly subluxed on oblique view.

[/DDET]

[DDET What would you do?:]

You are concerned about a bilateral posterior shoulder dislocation.

As we were unable to 100% decide whether these joints were in or out, we obtained a CT scan….

httpv://www.youtube.com/watch?v=V8atTnzhfKE

[/DDET]

[DDET The CT report:]

Right Shoulder:

• Comminuted fracture of the head, anatomical and surgical necks of humerus involving both greater & lesser tuberosity.
• Fracture through posterior aspect of the glenoid.
• Mild posterior subluxation of articular surface of the humeral head relative to glenoid.

Left Shoulder:

• Comminuted fracture involving the head, anatomical & surgical necks of humerus.
• Cortical irregularity involving inferior aspect of glenoid ?non-displaced fracture.
• Humeral head is posteriorly dislocated and wedged on the posterior aspect of glenoid.

[/DDET]

[DDET Posterior Shoulder Dislocations.]

Posterior Shoulder Dislocation

A rare event accounting for only ~2% of all glenohumeral dislocations. However, pay attention as this injury is missed in > 50% of initial presentations !!

Mechanics / Anatomy / History.

• A distinct mechanism of action is required to cause a posterior shoulder dislocation (forceful internal rotation with adduction).
  • Lat dorsi, pec major & teres major overcome the smaller/weaker teres minor and infraspinatus.
• Convulsive seizures or electrocution have been associated with this injury (a direct blow to the anterior shoulder or falls can also produce posterior dislocation).
• Subdivided into subacromial, subglenoid & subspinous dislocations.
  • 98% are subacromial.

Clinically…

• High index of suspicion based on mechanism.
  • Pain is not very reliable
• Prominence of posterior shoulder w/ anterior flattening “squared off appearance”.
• Arm held in adduction & internal rotation.
  • Inability to externally rotate.
  • Abduction is severely limited.

Radiologically…

Standard AP images can be deceptively normal whereas the lateral/scapular Y-view is diagnostic. Abnormal features include;

• Loss of ‘half-moon’ elliptical overlap of humeral head and glenoid.
• “Rim sign”
  • Increased distance between anterior glenoid & articular surface of humeral head.
• “Lightbulb” or “Drumstick” appearance of humeral head.
  • Occurs due to humeral profiling in internal rotation
• Reverse Hill-Sachs deformity
  • Impaction fracture of anteromedial humeral head.

Management.

• Urgent Orthopaedic consultation
• Closed reduction may be attempted
  • Requires generous sedation & may be more appropriate for the OT.
  • Axial traction is applied in the line of the humeral shaft, with gentle pressure applied on the humeral head. External rotation may help.
• ORIF may be required (+/- arthroplasty)
• Post-reduction:
  • Shoulder immobilisation (minimum of 4 weeks).
  • Orthopaedic follow-up.

Complications of Posterior Should Dislocation.

• Associated injuries include fractures to glenoid rim, greater tuberosity, lesser tuberosity & humeral head.
• Subscapularis may be avulsed from the lesser tuberosity.
• Neurovascular injury is rare (generally protected due to its anterior location).
• 30% of patients have recurrent posterior dislocation.
• Degenerative joint disease.

[/DDET]

[DDET The Follow-up…]

Firstly, here are the 3D reconstructions from his CT.

This patients’ injury had actually occurred the night before his presentation (some 14-15 hours earlier). Taking this into consideration, and given his associated humeral fractures it was decided that the relocation attempt should take place in the OT with a general anaesthetic and full muscle relaxation.

Despite multiple attempts/techniques his shoulder could not be relocated.

He returned to theatre 48 hours later for an open-reduction and internal fixation.

[/DDET]

[DDET References.]

1. Rosenʼs Emergency Medicine. Concepts and Clinical Approach. 7th Edition
2. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th Edition.

[/DDET]