Slings of outrageous misfortune…

I want to talk about some misunderstandings and ‘misfortunes’ I see and hear around the use of slings after shoulder injury or surgery and discuss how they may at times hinder more than help.

The arm sling comes in a lot of different styles and designs, from the basic triangular bandage to the all-singing, all-dancing ‘RoboCop’ looking one with its adjustable belts, buckles, and braces. Slings are often used after trauma such as fractures and dislocations, or surgeries such as rotator cuff repairs to protect and immobilise the arm and help prevent further damage.

Slings After Rotator Cuff Surgery

Wearing a sling after rotator cuff surgery is often advised to help protect the recently repaired tendon from re-tearing by preventing the rotator cuff muscle from pulling on it. However, this is not fully accurate as slings are really more to limit and reduce repeated movement rather than prevent rotator cuff muscle activity.

Placing an arm in a sling will limit shoulder rotator cuff activity somewhat, but a number of studies have shown that even with an arm in a sling, using the other arm during activities such as reaching overhead or pushing a door open produce as much rotator cuff activity in the immobilised arm as it would experience if it were moving (ref).

In fact, even just squeezing the hand whilst an arm is in a sling can increase its rotator cuff muscle activity to similar levels as when it is moving actively (ref). We also know that wearing a sling for longer DOESN’T reduce cuff repair re-tear rates (ref)

So if wearing a sling doesn’t significantly reduce rotator cuff muscle activity or reduce the risk of cuff repair re-tears, why bother with them at all? Well, the main reason for wearing a sling after surgery or trauma is for pain relief, but this is not achieved by reducing movement, but also by reducing fear and threat by increasing a sense of protection and safety just like an Elastoplast does for a grazed knee, or a plaster cast does around a broken bone… the tissue status hasn’t changed, just the perception of threat!

More Harm Than Help?

However, I think the effects of wearing a sling can at times be a double-edged sword producing over-protection and over-guarding that perversely increases muscle tone and activity, the exact opposite of what is wanted. I often see a lot of patients after rotator cuff surgery or shoulder dislocations in slings who hold their arms so tense and tightly into their body, with their shoulders hitched up to their earlobes, that they look ready to start a fight than resting and relaxing.

But this isn’t just the slings fault. I also think the surgeons, medics, and physios who tell people to wear slings often inadvertently scare the living shit out of them, telling them that they must not use, or must not move their shoulder at all or they will do more damage or harm to themselves. This I find increases anxiety and fear and rather than feeling protected in a sling they now feel on high alert.

Also, there is no real consensus or agreement on what is the optimal time to wear a sling after rotator cuff repair surgery, with times ranging from anywhere between 3-12 weeks. Some advocate less time in a sling to prevent stiffness, others more time to reduce the re-tear rate (ref) However many studies have shown that wearing a sling for longer does not necessarily reduce the risk of re-tears, or shorter reduce the risks of stiffness (ref).

Because of this, I think slings should be prescribed on factors other than their surgery or trauma. Things such as a patients age, their tissue and bone quality, co-morbidities, size and location of any tissue damage, their activity levels, psychological status, beliefs, expectations goals and aspirations. All these factors should dictate how long a sling should or should not be worn… not just the surgery or type of trauma.

Slings After Dislocations

Another common reason slings are worn is after traumatic shoulder dislocations. However, yet again there are some misunderstandings on their use, and again there is very little consensus on the optimal time and method to immobilise a shoulder after a dislocation, with times ranging from 24 hours to 8 weeks (ref).

There also has been some debate about what type of sling is best after different types of shoulder dislocations. With external rotation slings being suggested as a better option after anterior shoulder dislocations in a belief that they help drawback capsule and labral tissue defects towards the glenoid rim and help them heal better, so reducing recurrence of instability (ref).

However, recent systematic reviews don’t actually show any significant benefit of external rotation slings over standard internal rotation ones (ref). It is also known that patient compliance and tolerance with these external rotation slings is low, really low (ref). In fact, I recently had a patient hurl one across the gym at me, telling me to “burn that fucking thing” after wearing it for less than a week.

However, regardless of which type of sling you use, there are questions about the use of ANY sling after shoulder dislocation. Although a high prevalence of structural injury can be seen after a shoulder dislocation this often affects the passive structures of the labrum, joint capsule, and its ligaments, and often does not heal even after immobilisation (ref).

These passive structural defects can be important in some individuals as they do help stabilise the shoulder at end of ranges and during intense activities. However, as long as an individual avoids these positions and tasks in the early stages of rehab, and as long as they have robust progressive rehab it is thought some can adapt and overcome these structural changes and not have any further recurrence of joint instability (ref).

Another reason to not put a recently dislocated shoulder into a sling is that they are more likely to maintain their strength and motor control of the shoulder with active movements, but more importantly, maintain their neural and proprioceptive input. This will help reduce muscle atrophy and co-ordination deficits from occurring and potentially limiting progress.

In fact, could it be that immobilising a shoulder after a dislocation may make it more susceptible to further episodes of instability not less? Who knows, but it has been recommended by the British Orthopaedic Association and the British Elbow and Shoulder Society not to immobilise a first time dislocated shoulder for more than 1 week (ref).

So in summary the use of arm slings after rotator cuff repair and shoulder dislocation have some misconceptions and can cause some potential misfortunes. However, although arm slings can be used inappropriately they can also be really useful and beneficial and as usual, it’s not a one size fits all approach.

As always thanks for reading

Adam