How Your Rotator Cuff Prevents Shoulder Pain
By: Dr. Joshua Beyl, PT, DPT
You don’t know what happened. You were just playing catch with your child and you just threw “too hard” and the next day your shoulder hurt. Or maybe you were out cutting tree branches and the next morning you could barely raise your arm. How about you just woke up and had a pain in the shoulder that just did not go away or even got worse the more you used that arm. You decide to see your family physician and you hear the words “Your pain is coming from your rotator cuff.” You think “Great! But what is a rotator cuff and why is it hurting my shoulder?” Shoulder pain is very prevalent and effects thousands of patients every year and one of the biggest contributors to shoulder pain is the rotator cuff because of the role it plays in shoulder stability. But to understand why stability is so important let us first look at the shoulder joint.
What exactly makes up the shoulder joint?
When you picture your shoulder joint, I want you to picture a golf ball sitting on a golf tee. The golf ball represents the head of your upper arm bone or humerus, and the golf tee represents the small area, glenoid, on the shoulder blade, or scapula, that the head sits on. Now along with those two bones your collar bone, or clavicle, helps to complete the boney structures of the shoulder joint. There are multiple soft tissue structures in the shoulder that include tendons, cartilage, bursas, labrum, and joint capsule, and all play different roles in motion and stability. The shoulder is one of the most mobile joints we have and because of this stabilization is key.
How does the shoulder stabilize itself?
When we discuss shoulder stabilization it comes down to two types. The first is static stabilization which happens when the arm is rested at your side. In this case, the stabilization comes more from the ligaments, labrum, and capsule in the shoulder joint. The labrum is basically just adding some depth to the golf tee so that more of the ball is covered and stable. So, when you are not using your arm that is your static stability.
Where the rotator cuff comes into play is dynamic stability. Dynamic stability occurs the moment you start to move your arm. That is when the rotator cuff muscles must work together to keep the ball on the tee as it is spinning. When all four muscles contract together the head of your humerus is compressed down into the joint, or the ball is pushed down onto the tee to ensure it does not fall off. Along with the rotator cuff the muscles that control the scapula must engage to keep proper space in the joint to make sure tendons and other structures are not being compressed or damaged. So when you reach overhead to give a high five or even putting your shirt on in the morning that is your dynamic stabilization taking place.
What muscles make up your rotator cuff?
There are four muscles that make up the rotator cuff. The largest of the four is a muscle called your subscapularis. This muscle is located on the underside of your scapula in the area of your arm pit. This muscle is mainly responsible for internal rotation of the arm, so think about drawing your hand in toward your stomach for a nice pat after a nice large meal. The subscapularis tends to be the strongest of rotator cuff because of its size and how often we use it.
The other three muscles of the rotator cuff are primarily our external rotators of the shoulder. This motion is the opposite so think of drawing your hand away from your stomach as you prepare for dessert after your meal. The largest of these muscles is the infraspinatus. This muscle sits underneath the boney ridge felt on your scapula. Just above that boney ridge sits another rotator cuff muscle your supraspinatus. This is one of the most common rotator cuff muscles damaged in my opinion due to the location of the tendon and size of the muscle. The last of the external rotators is called your teres minor muscle and it sits along the side of the scapula.
What are the common reasons for shoulder pain?
When it comes to rotator cuff pathologies the most common I see in the clinic is impingement syndrome, rotator cuff tendonitis, and rotator cuff tears. Although these are considered different conditions, in my opinion, they are very much related. It is possible to progress from impingement syndrome to tendonitis and eventually a tear if the underlying issue is not corrected. We will break each condition down and you can decide which one you may fall under if you are having shoulder pain.
First we will look at impingement syndrome which is when tendons in the shoulder joint become pinched due to a lack of space in the joint. This lack of space can be primary, caused by anatomical structure of the joint, or secondary, caused by a weakness in the rotator cuff or the muscles surrounding the shoulder blade. The primary location of pain is typically the front and side of the shoulder and usually increases when you begin to reach at or above shoulder height.
We can further break down impingement syndrome into two subcategories based on which side of the rotator cuff is becoming impinged. The most common impingement occurs on the bursal side meaning the area of tendon that does not lay directly on the humerus. This is often referred to as subacrominal impingement because the tendon becomes trapped on the underside of the acromion, part of the scapula. The other type is articular side, or internal impingement, which occurs on the side of the tendon that does lay directly on the side of the humerus.
Each of these types of impingement can have different structures involved and can have different causes. A good physical examination from a physical therapist can help determine which category you may fall under. Treatment for shoulder impingement should focus on reduction of inflammation, improving motion of the shoulder joint as well as shoulder blade, and improving dynamic stability of the shoulder through exercises. A skilled physical therapist should be able to work with you to develop an effective plan of care based on your presentation.
The next pathology is rotator cuff tendonitis or tendinosis. This is when the tendon becomes inflamed due to overuse or possibly because of repetitive impingement. Pain from this usually is felt along the outside of the arm and can begin as soon as you begin to move your arm. This can happen to any of the rotator cuff tendons depending on the cause of the irritation. Again the treatment for this is to first reduce the stress to the tendon and reduce inflammation. You want to then address the underlying cause of the stress through either behavior modification or strengthening to improve tendon tolerance.
The last of the pathologies is a tear in the rotator cuff. The pain again is usually along the outside of your upper arm. Now, this may sound scary but actually, as medical imaging is becoming more prominent we are seeing that small tears are actually common even in asymptomatic (pain-free) people. What this means is that just because there is a small tear in one of your rotator cuff tendons it does not mean that the other three cannot compensate for the injured tendon or that the injured tendon cannot tolerate stress. I like to equate this to the idea of a thick boat rope you see holding the large ships down at the docks. Just because some of the threads in that rope have torn does not mean you have to through that rope away or even take time to repair those strands. The rope is still very much able to hold that boat at the dock. For smaller tears, this may be the case for your rotator cuff as well it just depends on the type of activities you are trying to return to. For those non-operative patients therapy will focus on reducing pain, strengthening the rotator cuff, strengthening the muscles parascapular muscles, and improving muscle coordination of the rotator cuff to enhance dynamic stability of the shoulder joint.
What Other Treatment Options Are Available?
When it comes to shoulder pain the most common treatments outside of physical therapy are injections and surgery. There are many options for injections, such as cortisone and PRP, and these can be helpful to a patient. However, as a therapist, I tell my patients it should be more of a secondary treatment along with physical therapy. The reason for this is the injection can help quickly eliminate the inflammation and decrease the pain that will allow you to tolerate more physical activity/exercise. While the injection is working let us take advantage and stress the tissues to address the underlying cause. The injection does not address the underlying cause just the pain and inflammation so unless it is a simple overuse injury that you do not normally perform, for example painting every room in your house, the injection will not fix the cause just mask the pain.
When it comes to surgery the recovery process can depend on many different factors from size of the tear, a number of muscles involved, previous level of activity, and your overall health. The rehabilitation process following surgery usually happens in phases and can be dependent on the surgeon’s protocol as to how long you are in each phase. Typically the first part is to focus on motion and trying to get as much motion back in the joint as possible. After the initial mobility phase, we begin light strengthening of the rotator cuff and parascapular musculature usually below shoulder level. Eventually strengthening is progressed to more overhead and activities away from the body to stress the rotator cuff and improve the dynamic stability of the shoulder joint. On average the rehabilitation process can take 3 months and it can be up to a year before you feel like you are back to one hundred percent.
There are many contributing factors to shoulder pain but I hope now you have a better understanding of what the rotator cuff is and why it plays such an important role in keeping your shoulder pain-free. If you do suffer from shoulder pain and after reading this you would like more answers or even begin treatment please feel free to contact any Advance Rehabilitation office near you. Most states and insurances allow us direct access meaning you do not have to see a physician before starting treatment.