The Rotator Cuff: Part Two
Welcome back to part two of the rotator cuff article series. Last week we talked about the basic rotator cuff information; how it is a group of four scapulohumeral muscles that aid in movement of the glenohumeral joint (shoulder joint) throughout much of its range of motion. We overviewed the terminology, anatomical location and responsibilities of each individual muscle in relation to the shoulder. This week we will discuss common injuries that occur with the rotator cuff.
As I talked about last week, due to the high reliance on dynamic stabilizers and poor bony articulations, the shoulder joint is extremely prone to injuries. To name a few; muscle strains, tendinitis, multidirectional instability and impingement are all common pathologies at the shoulder joint, often involving the rotator cuff. The tricky thing with these pathologies is, they often are caused by one another and cause the next injury, almost like a merry-go-round, which can turn into a very vicious cycle if not taken care of correctly. So, before we talk about diagnosis, rehabilitation and treatment, let’s break each of these common injuries down and how the rotator cuff group is involved.
Any time an injury occurs there is always a specific mechanism, or reason for onset. It may not always be clear to us based on if it is acute or chronic, but the better idea we have of that, it can make identifying the problem much easier. At the shoulder it is often difficult to determine injuries due to the intricacy of the shoulder joint. So many structures run through the joint; tendons, bursae, bony structures etc, that if one thing occurs it can lead to the onset of other injuries. Let’s start with a simple rotator cuff strain.
Rotator cuff strains are increasingly common in sport, due to many overhead activities and reliance on arm movement and also the responsibility we put on the shoulder to perform many actions throughout daily activity. Strains of any sort occur because of tissue attempting to withstand a load it cannot and from there it begins to stretch or tear. Strains can be graded on a 1,2, or 3 scale depending on the severity of the fibers stretched or torn. For reference, we commonly hear a grade three strain referred to as a “tear” so again it all depends on the severity of the damage.
Tendinitis can occur with any tendon, so let’s talk about general rotator cuff tendinitis first. Tendinitis can occur from repetitive micro traumas or overuse of the muscle fibers in question. Any term that ends in the suffix –itis, is referring to inflammation. So, tendinitis in nature, is referring to inflammation of tendons from the chronic overuse or micro traumas. If not treated correctly this can lead to long term, more chronic issues such as tendinopathies. These are generalized as diseases or deterioration of tissue and can lead to constant pain. This deterioration is caused from the acute injuries not being tended to and then exacerbated by the poor blood flow to each tendon and in turn, lack of healing.
Another common pathology the rotator cuff musculature is involved in is impingement. This occurs when the space that the rotator cuff tendons run through becomes decreased. This space, called the coracoacromial space is occupied by the supraspinatus and infraspinatus tendons, in addition to other structures including, but not limited to the subacromial bursa and long head of the biceps. When this space becomes enclosed, structures begin to rub on each other during movement and this can cause the rotator cuff tendons to become inflamed. This inflammation causes further closing of the subacromial space and cause increased pressure on the tendons. Possible long-term complications from this can lead to increased instability, decreased range-of-motion (ROM) and labral injuries down the road. This decreased ROM, specifically with internal rotation can lead to increased stiffness of the posterior capsule. This can cause further issues including weakness of the dynamic stabilizers of the GH joint, poor biomechanics of the shoulder and improper rhythm of the scapula. This can cause overhead movements, throwing activities and general daily tasks to become increasingly painful and bothersome.
The final injury I would like to briefly touch on is subacromial bursitis. When rotator cuff impingement, tendinitis go untreated, chronically this can lead to increased inflammation of the subacromial bursa and a further decrease of the subacromial space.
All of these injuries are distinct in nature, but as you can tell they are interrelated. Common signs and symptoms of many of these injuries are also very similar. Popping, clicking and pain are among the most common and they can cause pain in the shoulder, scapular or upper arm regions. Keeping that in mind, remember that tendinitis can cause impingement, and impingement can cause tendinitis and bursitis. It can be difficult to differentiate between one or the other in the acute setting, but if you are suffering from shoulder pain I urge you to do this: think about which motions bother you, what kind of pain you are having and how long it has been going on. All of these things can make diagnosing your issue much easier and allowing the proper steps to be taken in order to relive your symptoms. Always remember to #HealByMoving.