Shoulder Instability Part 2: Trauma

This is part 2 of my 4 part series on the unstable shoulder! In this piece we will be looking at trauma as a cause of unstable shoulders, you can read my introduction in the world of shoulder instability for a recap here.

So traumatic injuries that can cause shoulder instability are numerous, from the obvious glenohumeral joint dislocations, to labrum injuries such as SLAP lesions, to rotator cuff tears and not to forget injuries and dislocations of the acromioclavicular and sternoclavicular joints all of these trauma's can be a source of shoulder instability. However in this piece today we are just going to focus on the causes, presentations, complications and management of traumatic dislocations of the glenohumeral joint, ie when head of the humerus comes completely away from the glenoid.

X-ray of an anteriorly dislocated glenohumeral joint

The most common direction for a shoulder to dislocate is anteriorly, out the front as in the image above, this can happen with a direct blow to the shoulder or when the arm is rotated forcefully. Not as common is when a shoulder dislocates posteriorly, these only account for about 1-4% of all dislocations (source). Posterior dislocations where only thought to occur through fits, seizures or electrocutions, as true as this is, it is now known that a lot of posterior dislocations occur through normal trauma mechanisims (over 65% in fact) and because of this worryingly 50-80% of posterior dislocations are initially missed in A&E departments (source) & (source). They are easily missed due to a poor understanding of the mechanisms involved and also due to poor imaging choices, for example AP viewed X-rays can look perfectly normal as the humeral head sits in line with the glenoid, although a good tip is too look for the light bulb sign where the humeral head shape is more bulbous than spherical! But normally it's only when an axillary view, or a single slice CT scan is done can the posterior dislocation be seen. On a personal note I have had two missed posterior dislocations sent to me for physio following falls in the last 18 months so be aware and keep an eye out for them they are out there.

How to spot a dislocated shoulder

Radiographic imaging isn't the only way to spot if a shoulder is dislocated, there are obviously clinical signs. First and obviously is pain, lots of pain, and a lack and reluctance to move the arm or shoulder in any direction, they will be cradling the arm across their body and will not want to lift the arm or move their hand away from their stomach. The shoulder will also have an altered appearance with a loss of its normal rounded profile, looking rather square-ish, and there also maybe a step deformity present with a sulcus sign between the top of the shoulder and the acromioclavicular joint

A dislocated shoulder

So what should you do if you suspect a dislocated shoulder? Well it needs to be relocated asap as the longer it's out the harder it tends to be to relocate due to muscle spasm and pain, not to mention the ongoing trauma to the soft tissues and potential risk of neuro vascular compromise.

Relocation of a dislocated shoulder

But who should try and relocate a dislocated shoulder? This is a question I've come across many times and my simple answer is anyone who is qualified and confident in doing so, yes this is normally a doctor in an A&E department but if time is of the essence what about pitch side medical staff and physios?

There are numerous ways described in the literature to relocate a shoulder a great read for a review of them is this recent paper in the BJSM and this paper here. The simplest and easiest way I was taught to relocate a shoulder on a pitch side emergancy first aid course is by simply and gently externally rotating the arm, the myths of having to apply traction to relocate a shoulder is still around but it just isn't needed, if anything applying traction makes it worse as the muscle/tendon reflexes kick in and you end up fighting with shoulder rather than working with it.

HOWEVER… there are risks of further bony and labral damage during relocation so I was taught if there is no urgency to relocate the joint ie no loss of neuro vascular status eg pulses and sensation are intact and the player/patient is reluctant to move due to pain DO NOT attempt relocation, instead sling the arm, give analgesia, ice the shoulder and take to A&E.

WARNING: This blog is not to be used as a teaching tool or advice on how to relocated a dislocated shoulder, you must be taught by a qualified professional

Shoulder immobilisation

The next debate is should we immobilise a dislocated shoulder and how long for and in what position? Unfortunately with regards to how long to immobilise there is no simple answer to this, as its dependant on lots of factors such as the extent of bony and soft tissue damage done or not done during the dislocation, the age of the patient, past history of dislocations and other issues such as hypermobility or other medical conditions.

With regards to position of immobilisation after anterior dislocations there has been a gamete of research and claims that immobilising the arm in external rotation was best practice! This position was thought to help 'draw back' damage soft tissue to the bone and so increase the healing rate and reduce the chances of reoccurrence. However recent research shows no grounds for this (source), with no differences in reoccurrence rates and healing times, plus compliance and practically of wearing external rotation slings are horrendously poor, I defy anyone to try wearing one for a day let alone a few weeks! So standard slings are now is normally recommended by nealy all (source)

Of course all dislocated shoulders need a period of immobilisation, the joint has had a trauma and needs to rest and recover, but if minimal or no bony, labral or rotator cuff damage has been done then this period of immobilisation can be short, really short, sometimes just a week or two before we begin active rehab. If there is other structural damage or if the patient is older or has other medical issues that may delay healing rates then a longer period of immobilisation is needed maybe up to six weeks or more.

Common injuries occurred from dislocations

The most common bony structural injuries that occur from a dislocated shoulder are a Hill Sachs lesion named after two radiologists who first discovered them, or a Bony Bankhart lesion named after the eminant english orthopaedic surgeon Arthur Sydney Blundell Bankhart 1879-1952.

These can happen on both anterior and posterior dislocations with them being called reverse lesions when they are seen due to posterior dislocations

A Hills Sachs lesion is a humeral head 'indent' caused by edge of glenoid impacting on it as it dislocates, small lesions defined as under 1/8 of the total area of the humeral head are usually left and don't cause any issues, medium to large lesions normally need an operation especially if the lesion is 'engaging' during normal daily movements of the arm.

A bony Bankhart lesion is a fracture to the front or back inferior edge of the glenoid again caused from the collision between the humeral head and the glenoid but this time it's the glenoid that fractures. This also disrupts the labrum complex. If the fracture is small and not to displaced then a period of immobilisation and it can heal conservatively, however if the fracture is displaced or if the fragment is large they don't tend to heal and recurrent dislocations can occur and so surgery is indicated, this is where external bracing was thought to help!

Diagram of Hills Sachs and Bony Bankhart Lesions

And of course bony Bankharts and Hill Sach lesions can be, and quiet often are, found together.

Other soft tissue injuries that can occur with anterior dislocations are Labral Bankhart tears, where the fibro cartilage ring gets detached from the glenoid rim, these are usually described via a clock face so an anterior labral tear can extend from 12-6 o'clock and posterior can be from 6-12 o'clock, most usually occur between 3-6 o'clock, and again depending on a host of factors some are operated on some can be managed conservatively.

Other soft tissue lesions that occur with dislocations are HAGLs which stands for Humeral Avulsion Glenoid Lesion where the inferior capsule avulses away from the humerus, these are very difficult to diagnose and nearly all need surgery. GLADs which stands for a Glenoid Labral Articular Defect, where the labrum pulls some of the articular surface away with it. ALPSAs which stands for Anterior Labral Periosteal Sleeve Avulsion where the labrum rolls up like a sleeve and displaces medially around the front edge of the glenoid, and finally Perthes lesions where a Bankhart lesion strips the periosteum away medialy

So depending on what has been damaged and how much will depend on whether conservative or surgical management is warranted.

Physiotherapy for shoulder dislocations

So physiotherapy management for a shoulder dislocation will be dependant again on all the same factors we have just discussed above eg age, damage done, apprehension, nerves, functional goals etc etc but in simple terms we want to address the dynamic control of the shoulder joint, focusing on the rotator cuff to begin with, then incorporating the other shoulder prime movers and scapula muscles, gradually increasing the range and exposure of load and resistance to the cuff and the shoulder joint as things improve. With anterior dislocations obviously the anterior cuff will be a primary area to focus on, with posterior dislocations, yep you got it the posterior cuff.

Initially I find the best way to start rehabbing a dislocated shoulder is in closed kinetic chain positions. The benefits if this are multiple. First closed kinetic positions increase cuff co-contraction which of course produces better humeral head control on the glenoid, just want an unstable shoulder needs. This reduces joint shearing forces and so sensations of instability, which is priceless in building and restoring a patients trust and confidence after a traumatic dislocation.
Next the compression of the joint in closed kinetic chain positions gives much greater proprioceptive feedback and again can help develop a better connection with the cuff and shoulder joint. Finally they are also a great way to strengthen everything around the shoulder, from the cuff to the prime movers to the peri scapula muscles.
However we also want to work on isolated cuff strength in both closed and open kinetic chains. To start with this is in below shoulder height positions. This can be as simple as isometric contractions, buliding into concentric / eccentric work through range using weights, and or therabands etc. A tip though when trying to focus on the anterior cuff, ie Subscapularis, remember that pecs wants to do most of the work and easily dominates the internal rotation movements so Subscapularis can remain weakend underneath, ensure to do exercises that minimise pecs but emphasis Subscapularis this paper is a good start for that.

When performing rotator cuff rehab we usually keep the repetitions in the high zones, between 15-20RM with light-ish resistance. Reasons being as we are looking to encourage muscle and tendon endurance and capacity. However, we are also looking to build its strength and power which is also a key part of the rotator cuffs role. Therefore, occasionally, and when its ready and safe to do so, I feel it is vital to ask the rotator cuff to strengthen with heavier weights and lower reps, down to 6-8RM sometimes.
Training the cuff to react and feel faster speed of movement is also important, and in needs to be trained to react to sudden changes in movement and from sudden changes in concentric to eccentric actions. Perturbation training is excellent for this, again usually in closed kinetic chain positions building to open chain.
Eccentric strength training is also vital for the cuff to adapt to, especially in sports activity. Training the cuff to decelerate shoulder movements is a key function and needs to be started as soon as possible.
However, shoulder rehab after a dislocation isn’t all about strength and power. A major goal is to also reduce fear and apprehension and build the patients faith and trust back into the shoulder.
Starting rehab in positions where the patient feels safe and secure is therefore key in the early stages, reducing any threat or feeling of instability. However once the cuff and other muscle function begins to improve then pushing the envelope and challenging the patients neuromuscular and central nervous system, by placing and exercising the shoulder into more challenging positions is vital.
Rehabbing the shoulder in positions that can make the patient feel uneasy can be difficult for both the patient and therapist but is essential to do, not only for restoring its strength and control in outer ranges but also to restore confidence and trust into the shoulder again. This of course has to be sensibly done, and a graded exposure to uneasy and apprehensive positions is essential. Don’t suddenly go making your patients mistrust you or their shoulder all over again, or you will be back to square one very quickly. Slowly, steadily and surely encourage and build the trust over the weeks and months.
Also should we be exercising rotator cuffs to fatigue in rehab? This is a question that has divided many physios, and it depends on many factors, but in my opinion the simple answer is yes, BUT with caveats.
As I have said the cuff needs to improve its strength, endurance and power after a dislocation, and the quickest and simplest way to achieve this is by fatiguing the muscles to stimulate adaption. The amount of load and resistance can be variable, its a myth that you can’t get strong lifting light weights, it just takes longer and won’t be as effective as using heavy but working to fatigue is key!
However, common sense dictates that the cuff is still be needed to control the shoulder during normal activity after rehab. If it has been fatigued, and the patient goes and starts doing shoulder movements before the cuff has recovered then it could end in tears. So choosing when to fatigue the cuff is vital. Don’t ask a patient to do it first thing in the day, don’t get them doing it as there first exercise of the session and don’t ask them to do it before other high level or repetitive activity is planned

As things improve we should begin to see an increase in the range that the patient feels comfortable and confident to work in, with increasing positions of flexion, abduction, and rotation.
We should start to add different speeds of contractions, some slow some fast, again dependant on circumstances, we ensure that range of movement is improving and any stiffness is addressed. Most stiffness post shoulder dislocation tends to to guarding or pain dependant and so most don’t like to be stretched passively, and in my experience most don’t need to be. Most range of movement is restored through time and when a sense of control is restored with increased strength and co-ordination of the cuff and other shoulder muscles, if they do need or want to stretch let them do it themselves, a sense of control is essential with dislocated shoulders, and so I am usually 100% hands off with dislocations, as with most things actually.

Example of closed kinetic shoulder exercise

Remember to look at peri-scapular muscle work, and in late stages start to incorporate more challenge tasks and drills dependant on their presentation and ultimate goals eg throwing, sport related drills and joint contacts, knocks etc, I love crash mats for these, great fun.

So that's a whistle stop tour of glenohumeral joint dislocations and their management, as I said earlier please don't think you are ok to relocate a shoulder if you come across one just because you have read this, remember to be on your guard for posterior dislocations sent to physio as just a soft tissue injury following a fall, and when doing your rehab with a dislocated shoulder, remain hands off, focus on the cuff control and endurance and never, ever exercise a rotator cuff to fatigue in an already stability compromised joint!

Once again thanks so much for taking the time to read my stuff, I hope you find it useful, all comments greatly appreciated and I will try and get the next two pieces done ASAP. Part three will be on Type 2 causes of shoulder instability eg non trauma structural issues, part four is on Type 3 causes of shoulder instability that being adverse muscle patterning.

Enjoy your sport

Adam