So a tear of the rotator cuff is pretty disastrous, right? It means surgery, right? Well NO it doesn’t! As our understanding and knowledge of the shoulder joint improves so does our ability to recognise those cuff tears that are going to do ok without the need for surgery, let me explain more.
It has been well known in the medical world for quite sometime that there are a lot of people out there with tears in their rotator cuff tendons functioning normally with no pain and not even aware of them. Templhof et al back in 1999 published a study that checked the shoulders of people with no pains or reported problems, and 23% of them had cuff tears! Thats nearly 1 in 4!!! However, this study was done on the ‘older’ generation ie 50 years old and onwards, and they also found the older you are the more likely you are to have a tear, no real surprise here I guess, but what is surprising is the numbers, over half of all the 80 year olds they looked at had tears but no problems!
So its fair to say the older you get the more chance you have of cuff tears, but there is also a high chance you maybe blissfully unaware of this, great!
This anomaly of tears in the rotator cuff with no symptoms isnt just seen in the older generations either, it is also seen in younger and more sportier people too, Conner et al showed 40% of elite over head athletes have rotator cuff tears with no reported problems, even better!
So why is this? Why are there so many people out there with tears in the rotator cuff functioning normally, and what can we learn from those that have tears with no pain or loss of function.
Well first we need to look at the location of the tears in the cuff, although the cuff works synergistically together and needs balance in all areas, some parts of the cuff can be classed as more important than other parts in terms of structure and function.
To help with working out which parts of the cuff these are we have to think of the superior rotator cuff as a suspension bridge! Confused? Let me explain more…
Burkhart et al, first used this description when he described a thickend section (nearly 3 x as thick as the rest of the cuff) in the supraspinatus and infraspinatus tendons, which he called the cable, in front of this was a thinner poorly vascularised section of the cuff, which he called the crescent. He explained how the cable can ‘bypass’ the crescent and tranfer load between the anterior and posterior portions of the cuff and so ‘shield’ the crescent in front of it. Just like a suspension bridge cable carries the load from one pillar to the other across a span. See the images below
B= crescent C= cable S=supraspinatus I= infraspinatus BT= biceps tendon
So a tear in the ‘crescent’ area of the cuff can be thought as not too much of an issue functionally for the shoulder, as the cable behind it can continue to take and distrubute the load and tension between the anterior and posterior rotator cuff. These means the superior cuff can continue to dynamically stabilise the humeral head and prevent superior humeral head translation on arm movement. However, if the tear goes through or is behind the ‘cable’ of the cuff this means the superior cuff cannot comminicate effectivly with the anterior and posterior sections and so as the superior cuff weakens it cannot balance the forces on the humeral head and so it can translate superiorly and compresses under the subacromial arch causing pain, irritation and even stopping the arm from lifting completely, called pseudo paralysis.
Now the crescent area of the cuff is thought to be where most cuff degeneration starts due to its poor vascularity and also due to the high demands placed on it in depressing the humeral head against the opposing force of the deltoid as the arm raises. This means there is a good chance that most superior degenerative cuff tears start here in the crescent. However, if the tear settles and stabilises and doesn’t progress through the cable then the shoulder can happly function as normal. It is these cuff tears that the above studies see in people living normally with no pain or loss of function. However if the tear progresses and or is large enough to go through the cable, these tears cannot function well and suffer limitations in activity.
So how do we know if the tear is in the crescent or the cable?
Surely the amount of pain in the shoulder gives us a clue if its small or large cuff tear? Well actually NO I’m afraid not, pain is bad indicator of the amount of cuff damage, in fact it has been found that smaller partial cuff tears can be MORE painful than bigger tears? Gotoh et al found that when the cuff tendon is only partially torn it releases more pain chemicals that when fully torn, also Carr et al found that its more likely the bursa above the cuff that generates the pain than the cuff tear itself due to its rich innervation further confusing the picture. Anecdotally I have seen small tiny cuff tears make fully grown hard men cry like babies, and conversely seen massive huge cuff tears produce very little discomfort, so as a rule, pain just cannot be an indicator of damage or a prognosis of outcome.
So if we can’t use pain what about function, well yes this does help inform us if there is a crescent or cable tear. Pseudo paralysis or what’s called a drop or lag sign where you can’t hold your arm in certain positions does tell us that the cuff is badly torn with cable involvement. BUT don’t jump the gun, I have seen pseudo paralysis in shoulders in the first acute stages of small partial crescent tears that can resolve spontaneously within a few weeks just due to the pain levels.
So really the only true way of knowing if a cuff tear is affecting the crescent or cable, or both, is through imaging or directly looking at it via arthroscopic (keyhole) surgery. MRI is usually the best way of visualising the exact location of cuff tears, as well as the quality of the muscle behind the tear, important in deciding what type of surgery will or won’t help. Ultrasound scanning is also useful for looking at the rotator cuff, its quicker and cheaper to use, but it can be tricker to interpret and you cant always see all the bits you want to. I have been using ultrasound scanning in my clinics for over three years now and I’m still learning and still often send for an MRI to confirm what I think I may have seen. Although a lovely little paper by Morag et al that I found this week shows that with care and skill using an ultrasound scanner the rotator cuff cable and crescents can be seen.
So in summary, if you perosnally have, or see a patient with shoulder pain and think it maybe a rotator cuff tear, don’t jump the gun and don’t think it automatically needs surgery, it needs investigation to determine if its in the crescent or cable combined with other factors before a prognosis can be made. Also remember a lot of rotator cuff tears can settle and manage very well with very little intervention. And finally remember that pain levels and cuff tears are completely unrelated.
As always thanks for reading
This is article is intended for information purposes only, if in doubt please consult your doctor or physiotherapist for further advice.