So I’ve just butchered a well known Shakespeare quote for this blog as 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 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 robo-cyborg-killer-cop movie, however, there are a lot of misconceptions about why they are used.
Slings After Surgery
Slings are often used after shoulder surgery such as rotator cuff repairs, in a belief that a sling protects a repaired rotator cuff tendon from re-tearing by reducing its muscle activity. However, this is not actually correct. Wearing a sling after cuff surgery is more to restrict movement NOT muscle activity.
Ok so limiting movement will reduce muscle activity somewhat, but EMG studies have shown that even with an arm immobilised in a sling just using the other arm during common activities such as reaching up overhead, or pushing open a door, can produce as much muscle activity in the immobilised shoulder as it would experience if it were moving on its own (ref). Even simply squeezing the hand whilst an arm is immobilised in a sling can increase muscle activity to similar levels as when it is moving (ref). We also know that wearing a sling for longer DOESN’T reduce re-tear rates (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 the main reason for wearing a sling after surgery is for pain relief and I believe it does this not just by supporting or limiting movement, but also by reducing fear and threat by producing a sense of protection and safety, a bit like a sticky plaster does on a grazed knee, or a plaster cast does on a broken bone.
However, the effects of wearing a sling can be a double-edged sword as they can also instil a sense of fragility and vulnerability that produces over protection and over guarding increasing muscle tone and activity, the exact opposite of what is wanted. I see a lot of patients after rotator cuff surgery in ill-fitting slings holding their arm tightly glued across their body and their shoulders hitched up to their earlobes more tense and anxious rather than relaxed and protected.
But this is isn’t just the slings fault, it is also the orthopaedic surgeons and ward physios scaring the shit out of and putting the fear of god into patients telling them that they must not use or move their shoulder or they will re-tear their tendon, talk about the nocebo effect at work.
There is also no agreement as to what is the optimal time to wear a sling after rotator cuff repair surgery, with times often ranging from 2 to 6 weeks. Some advocate less time in the sling to prevent long term post operative stiffness (ref). But others show that wearing a sling for longer does not result in any significant postoperative stiffness complications (ref).
So wearing a sling after rotator cuff surgery does not reduce muscle activity as much as we think, or prevent re-tears, and how long someone should wear one is not known. So because of this, I think slings should be prescribed on individual factors not simply routinely on a one size fits all approach. Size and location of the tear, tissue and bone quality, patient’s age, general health, activity levels, and their psychological status all should dictate how long a sling should be worn for.
Slings After Dislocations
Another common reason arm slings are worn is after shoulder dislocations. However, yet again there are some misunderstandings on there use. Again there is very little consensus on the optimal time and method to immobilise a shoulder after dislocation. For example, after anterior shoulder dislocations external wedge slings have been suggested as a better option as they are believed to helps drawback any capsulo-labral defects towards the glenoid rim and help there healing and restoring joint congruency, preventing recurrence of instability (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, recently 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.
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 have some misconceptions and can cause some misfortune. However, although I do see arm slings being used way too much, for way too long, I also see them helping some patients if used judiciously and sensibly.
As always thanks for reading