So I’ve just butchered a Shakespeare quote from Hamlet for this blog as I want to talk about some misunderstandings and ‘misfortunes’ I see and hear around the use of arm slings after a shoulder injury or surgery, and discuss how they may hinder more than they help.
The arm sling comes in a lot of different styles and designs, from the basic triangular bandage, to the all singing, all dancing abduction wedge with its adjustable belts, buckles, and braces looking like something out of a cyborg movie. Arm slings are used for many different reasons, such as protection, support, and of course immobility. However there are a lot of misconceptions about slings.
Slings for Shoulder Surgery
Arm slings are often used after shoulder surgery, particularly after rotator cuff repairs, however why they are used is often misunderstood. For example the belief that a sling protects a repaired rotator cuff from re-tearing by reducing or limiting muscle activity is not technically correct.
Ok so wearing a sling will restrict arm movement and so limit muscle activity due to less movement, but EMG studies have shown that even with an arm immobilised in a sling, using the other arm during common activities such as reaching up over head, or pushing open a door, can produce just as much muscle activity in the immobilised shoulder as it would experience if it were moving (ref). Even just squeezing the hand to grip things whilst an arm is immobilised in a sling can increase a shoulders muscle activity to similar levels as when the shoulder is moving (ref).
There is also no agreement as to the optimal time to wear a sling after rotator cuff repair surgery, with times commonly ranging from 2 to 6 weeks. Some advocate less time in the sling to prevent long term post operative stiffness (ref). But others disagree and show that wearing a sling for up to 6 weeks after surgery does not result in any significant complications with stiffness (ref). However, the other belief that wearing a sling for longer periods after rotator cuff repair surgery prevents or reduces re-tear rates also doesn’t appear to be justified either (ref).
So if wearing a sling doesn’t significantly reduce shoulder muscle muscle activity or reduce re-tear risks then why bother with them at all?
Well I think there is a psychological effect of having the arm supported and cosseted in a sling for a while after painful surgery. This psychological effect of protection I believe helps with pain relief by supporting arm arm, but also by reducing fear and threat and other placebo effects, just like a sticky plaster on a grazed knee helps with the pain.
However, I also think the psychological effects of wearing a sling can be a double edged sword. Yes they can help by producing a sense of protection and safety, but they can also in some produce a sense of fragility and vulnerability. This can lead to over protection and over guarding and could increase muscle tone and activity, the exact opposite of what we want.
So wearing a sling after rotator cuff surgery may not reduce muscle activity as much as we think, or prevent re-tear rates as much as we think. Why, and how long someone should wear a sling after surgery I think should be based on many other factors, not just a one size fits all approach. For example the patients age, the size and location of the cuff tear, the amount of tendon retraction, the tissue and bone stock quality, the patients general health and activity levels, and their psychological status. All slings should be ‘prescribed’ on these individual factors, not just a set number of weeks used for everyone and everything.
Slings for Shoulder Dislocation
Another common reason slings are worn is after a shoulder dislocation. However, yet again there are some misunderstands on there use here. First there is very little consensus as to the optimal time and method to immobilise a shoulder after a dislocation. For example, there has been a lot of research into the use of abduction and external rotation slings after anterior shoulder dislocation. The belief was that these slings help draw back capsulo-labral defects towards the glenoid rim and help with the healing of these tissues back to the bone, restoring joint congruency and preventing further recurrence (ref).
However, recent systematic reviews don’t actually show any significant benefit of these external rotation slings over standard internal rotation ones (ref). It is also known that patient compliance and tolerance with these abduction and external rotation slings is low, really low (ref). In fact just last week I 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 on the insistence of a surgeon.
The dreaded external rotation sling (burn that f**ker)
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 only usually affects the passive structures of the glenoid labrum, the joint capsule and its ligaments (ref).
These passive structures only help to stabilise the shoulder joint towards the end of ranges, and therefore as long as the individual avoids these ranges for a few weeks they are unlikely to suffer any recurrence of joint instability. Also if a recent dislocated shoulder is NOT immobilised in a sling they are more likely to maintain not only the strength and control of the muscles of the shoulder, but more importantly they will maintain the central nervous systems cortical representation of the shoulder, as well as its proprioceptive ability, which can only be a good thing to help with the joints ongoing stability in the future.
Could it be that immobilising a shoulder after a dislocation may make it more vulnerable to further episodes of instability not less? It has now been recommended by the British Orthopaedic Association and the British Elbow and Shoulder Society not to immobilise a dislocated shoulder for more than 1 week (ref).
So in summary the use of arm slings after shoulder dislocation and rotator cuff surgery has some common misconceptions and can cause some misfortune in producing some negative physical and psychological effects that may be detrimental to long term outcomes. However, although I do often see arm slings being used way too much, for way too long, I also see them helping some patients if used for the right reason and used judiciously and sensibly.
As always thanks for reading