An injury term that we commonly hear about in the media, around the water cooler or in conversation is the sports star, colleague or team mate that has ‘done their rotator cuff’. We know that’s something to do with the shoulder, and that it’s usually not a good thing. But what exactly is your rotator cuff, and what is meant exactly by ‘doing’ it? To answer this, and many other vexing questions, read on…
Shoulder Structure & Function
The shoulder is a remarkable piece of engineering. It’s the most mobile joint we’ve got, and yet can sustain incredible forces & speeds without falling to bits. A big part of what makes the shoulder so flexible is the disparity in size between the ball (humeral head) and socket (glenoid) that make up the joint. The “golf ball on a tee” analogy is well founded…
What you gain in range of motion with this kind of setup comes at the cost of stability, which explains why the shoulder has the highest rate of dislocation of all the body’s joints. Some stability is derived from the surrounding soft tissues – the glenohumeral ligaments and joint capsule, the labrum – but not an awful lot. That’s where the rotator cuff comes in.
The rotator cuff is a collective term to describe a group of four small, specialized muscles surrounding the shoulder – supraspinatus, infraspinatus, subscapularis & teres minor. What they have in common is their job, which is to keep the humeral head centered on the glenoid at all times, but especially when the shoulder is in motion. Larger, more powerful muscles such as the pecs, lats & the deltoid can generate large amounts of speed & force, but it is up to these four little muscles to hold it all together in the process!
The four muscles all originate on different parts of the shoulder blade, then converge onto the humeral head to attach in a circular fashion – in a cuff! Relative degrees of muscle contraction from the four work to keep the ball nicely centered on the socket & prevent it from falling apart, regardless of what you’re doing with the shoulder, be it vigorous activity like throwing or swimming, or something more sedate like reaching or washing or using a computer mouse.
This is termed dynamic stability, and it’s the rotator cuff’s main role. This not only prevents the shoulder from falling apart when you use it, but also allows forces to pass through the shoulder en route to their destination – for example, the immense forces a pitcher can generate in their legs & torso in the wind-up that have to be transferred efficiently all the way through to the baseball, require a secure shoulder through which all that force can pass.
Damage to the Cuff
The part of the cuff that is most often damaged are the tendons as they converge around the humeral head. There is a variety of causes, ranging from trauma, overuse, poor posture, and unfortunately, the normal ageing process. Beyond the age of 40, blood flow to the rotator cuff tendons starts to slow down a little, meaning that damage occurs more readily, and when it does, heals more slowly, or, in many cases not at all.
Not all rotator cuff tears get treated the same way. Factors that influence the choice of treatment include the age of the patient, the mechanism of the injury – trauma vs overuse vs degenerative, and the extent of the injury.
An example of the decision-making process re: managing a cuff tendon injury might go like this:
A patient that is:
- young – tendon likely to heal better;
- sporty – operates at a higher level;
- painful – ie. symptomatic;
- has partial thickness undersurface tear – statistically more likely to progress to a full tear;
is more likely to progress to surgical repair than someone who is:
- older – less blood supply therefore likely to be poorer quality tissue/healing potential;
- sedentary – not requiring as much from their shoulder;
- sometimes painful – possibly able to manage with activity modification & medications
- has a partial thickness upper surface tear – less likely to progress to more advanced damage;whose first line of management would more likely be physical therapy (ie. conservative management), +/- cortisone shot.
The role of Physical therapy and Rotator Cuff damage
A skilled PT can not only guide a patient through the process of optimizing their cuff function, but they can identify and correct postural abnormalities or other bad habits that may have contributed to the original problem, or otherwise prevent or restrict their abilities in the future. Regardless of whether a cuff tear is managed surgically or conservatively, the physical therapist has a central role to play in returning an individual to their desired capacity. Most commonly this takes the form of selected manual therapy techniques to reduce muscle tightness & undesirable tension, joint mobilization to reduce stiffness and specific exercises to improve muscle firing patterns & timing or to increase strength.
About the Author:
Derek Mansfield is KIMA’s shoulder specialist, having completed extensive post-professional training in Australia and the US, and having been the PT for the Australian Men’s Indoor Volleyball program between 2003 & 2013. He combines the use of cutting edge technology with evidence-based assessment & treatment techniques that are customized to suit the needs of the individual, and collaborates with some of New York City’s top shoulder surgeons. He can be found at KIMA Monday thru Friday, and in 2015 is celebrating his 20th year as a PT.