An algorithmic approach to anterior GROUP shoulder dislocat

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No patient is the ever same and this adage goes for anterior group shoulder dislocations (subcoracoid (I), subglenoid (II), and the rare subclavicular (III) and intrathoracic(IV)). These are different injuries so if you use the same technique every time there is going to be situations where you are less successful or are simply using the wrong technique. That’s why I take an algorithmic approach to the patient in front of me. This includes addressing patient, positioning, and injury-type factors.  There are anatomical reasons why no technique works every time on every patient and it is important to be skilled in several methods so you can use the best method for each presentation. The anatomically based techniques discussed rely upon the relative movements of the humeral head and the glenoid fossa of the scapula. Used correctly, these techniques require little or no force.

Here’s the generic algorithm, that will take you from recognising an anterior group dislocation all the way to  individualising care for your patient a choosing the most appropriate technique for the particular injury.

Once you have mastered a few techniques you can adapt this to your particular skill set. For example, if your favourite zero position technique is FARES, then that fits into your own algorithm for Type II cases – my personal algorithmic approach is shown here.

Before we step through this in detail, let's take a patient centred approach.

Patient, Position (adduction - yes/no), Dislocation (type and associated injuries).

This includes addressing whether the patient is young and fit or elderly and frail, whether they need an X-Ray, what type of injury they might have, whether they need sedating, and pre-planning what to do if your Plan A fails. 

When you get a patient who comes in with a dislocation, it's not a case of just "okay, they've popped their shoulder out and I'm going to now attack them with a particular technique." It very much depends on the patient in front of you. This is important because most of the research in this area concentrates on mainly males, and mainly aged 18 to 35. They're not always the types of patients that we see - you may have an elderly patient who's fallen down some stairs rather than an athlete on a ski slope.

So, I take an individualised approach to every patient. Are they young, fit and healthy with clear landmarks and good anatomy? Or, are they someone who has significant airways disease? 
Are they warfarinised? Are they confused or cognitively impaired due to dementia, intoxication or head injury? 

This question comes down to whether or not you have enough information from the patient history and clinical examination to be sure that you are dealing with a dislocation rather than a potential humeral shaft fracture or other dislocation mimic. Anyone with a significant fall or impact,  elderly, cognitively impaired or abnormal bone increases the risk of of mistaken diagnosis or associated fracture with the dislocation. 

Mechanisms less likely to result in shaft fracture are 'pull' or 'throw.' Landmarks include a step below the acromion (point of the shoulder) where normally you have the fullness of the humeral head rounding off the shoulder. If the head is sitting subcoracoid you will feel this fullness anteriorly, if it is subglenoid you will feel it in the axilla.

90% of patients can have their shoulders reduced without the use of any medications at all. 
So the vast majority don't need analgesia or sedation if you are able to position them in Analgesic position 1 (for SC) or Analgesic position 2 (for SG) ready for the appropriate reduction technique. For the remaining 10%, some need a little bit of analgesia and some patients need a full anaesthetic.  

The aim is to provide your patient with comfort and switch off the muscular spasm that is blocking the return of the humeral head to the glenoid fossa. It is not to see whether you can reduce the joint without drugs. If you do use some analgesia/sedation once you have reduced/removed the spasm then use an anatomically appropriate technique even if it is the same technique you have attempted prior to relaxation - you will likely find success having removed the block.

When we think about anterior group shoulder dislocations, we need to think about what injury we're treating.  Type III (subclavicular) and IV (intrathoracic) three are rare and associated with high velocity, high impact injuries. 
If you see one of these, then you need to worry about vascular injury and thoracic injury.

I'm going to focus on Type I (SC) and Type II (SG) injuries.

There are some useful clinical and radiological features that can help you assess what subtype of anterior group dislocation you are dealing with, as well as how much muscular spasm is in play, and how that may need to be managed to give you the best chance of success with your reduction attempt. There are features for Type I and II injuries that further split the presentations into classic (a) and variant (b) types.

There are currently no clear radiological guidelines to distinguish between these subtypes of anterior group dislocations. A retrospective case review (submitted for publication)  has shown that one measurement on an AP X-Ray will consistently separate subcoracoid and subglenoid subtypes. This is the IGIANV - take the distance between landmark points of the inferior glenoid (IG) and the inferior point of the anatomical neck (IAN) which appears as a notch on the Xray. Then take the vertical (V) measurement.

<44mm is subcoracoid

>44mm is subglenoid

Guideline developed by myself and Dr Andrew Long

Green line - IG to IAN

Yellow line - horizontal level of IAN

Blue line - IGIANV

IGIANV<44mm is subcoracoid

IGIANV>44mm is subglenoid

Small acromial step

Anterior fullness

Able to adduct

IGIANV <44mm

Start position - Analgesia position 1

Sedation/analgesia - for comfort

Technique :

First line - Adduction techniques (Cunningham, Kocher's)

Second line - Zero, scapular manipulation, Stimson

Cause - lots of spasm

Held in abduction (red lines)

Larger than expected acromial step (yellow arrow)

XR - small IGIANV, large scapulohumeral angle

Humeral head wedged up tight beneath coracoid process resulting in anterior fullness (blue arrow)

Start position - Analgesia position 1

Sedation/analgesia - for removal of muscle spasm (barrier to reduction)

Technique :

First line - Adduction techniques (Cunningham, Kocher's)

Second line - Zero, scapular manipulation, Stimson