Shoulder pain is one of the most common complaints that brings patients to our office. Many things can cause shoulder pain, including tendonitis, impingement syndrome, bursitis and problems with the joints. Shoulder pain can also be referred from muscles in your neck, rotator cuff or arm.
The Glenohumeral Joint
Your shoulder is a special joint. The main joint, the glenohumeral joint, is where the bone in your upper arm attaches to the shoulder blade. It is a ball in socket joint, like your hip. A ball in socked joint is exactly what it sounds like. There is a ball on the end of one bone, the arm bone. There is a cavity or “socket” on the other bone, the shoulder blade. The ball on the end of the arm bone sits into the socket part of the shoulder blade. This allows the arm to move and rotate in a bunch of directions.
Now, for what makes the shoulder special. As I mentioned, the hip is also a ball in socket joint. But the hip joint has a deep socket, called the acetabulum. Imagine a softball sitting in a bowl – there is a bunch of the bowl that wraps around the softball. This is stable and can support a bunch of weight.
The shoulder is different. It has a very shallow socket, called the glenoid. Think of a golf ball sitting on a tee. This setup allows for a lot more mobility. This lets us climb, throw, brush our teeth and about a million other things that make us who we are as humans. Now, this mobility comes at a price – the joint is way less stable than the hip.
The Rotator Cuff
Instead of having a deep, stable, bony socket, the glenohumeral joint has a group of muscles, called the rotator cuff, that hold it together and stabilize it during functional motions. The rotator cuff consists of four muscles: the supraspinatus on top, the subscapularis in front, and the infraspinatus and teres minor in the back.
Tendons are what attach muscles to bone. The rotator cuff tendons attach to the top of the upper arm bone, near where the ball is. The tendons – especially the supraspinatus tendon – have to pass under a part of the shoulder blade called the acromion. Normally, there is about 9-10 millimeters of space for the tendon to pass through. There is a little sac of fluid, called a bursa, that normally cushions the tendon as it passes under the bone.
There are two other joints that make up the shoulder joint. One is the acromioclavicular (AC) joint. It is where the collar bone attaches to your shoulder blade. The other joint is the scapulothoracic (ST) joint. This is where your shoulder blade slides over your rib cage. It isn’t a “true” joint, because it isn’t surrounded by a fibrous capsule, but it is very important for athletes and everyone else who is suffering from shoulder pain.
Causes of Pain
Shoulder pain is common in middle aged people, in people who work construction or similar professions. It is also common in swimmers, throwing athletes, weight lifters and other people whose sporting activities involve spending a lot of time reaching overhead.
Some of the more common causes of shoulder pain include bursitis, tendonitis and impingement syndrome. Bursitis is a condition where the bursa – the “water sack” that lubricates the tendon – gets irritated, swollen and inflamed. Tendonitis of the rotator cuff tendons (or the biceps tendon) can also cause pain on the front or outside of your shoulder.
Impingement syndrome is a bit more complicated. With impingement syndrome, the space between your arm bone and the acromion gets smaller – and the rotator cuff tendon can rub against the bottom of the acromion and get irritated.
Digging a Little Deeper (muscle imbalances, etc)
Let’s take a closer look at what happens when you move your shoulder. When you lift your arm, the ball at the head of your arm bone rotates. It also slides upward and forward a little bit. The infraspinatus and subscapularis muscles help control this movement and make sure that it isn’t excessive.
There are lots of interesting things that happen with the scapulothoracic joint, too. When you raise your arm to the side, the shoulder blade has to rotate upward 1 degree for every 2 degrees that the GH joint moves. This is called the “scapulohumeral rhythm”. The shoulder blade also needs to slide around the rib cage in a controlled way. Near the top of arm elevation, the shoulder blade has to be able to tip backward a a bit to low full range of motion.
So what happens when there are muscle imbalances?
Clearly, movements of shoulder are complex. Imagine a symphony. If one of the musicians is playing out of time, the whole thing ends up not sounding good. That’s sort of how the shoulder works. For instance, if the rotator cuff muscles are weak (or there is a problem with the joint capsule), the head of the humerus (the “ball”) can move upward too much.
Lots of things can happen at the scapulothoracic joint. For instances imbalances between the different portions of the trapezius muscle in your upper back or with the serratus anterior (the muscle between your shoulder blade and the rib cage) can keep our shoulder blade from rotating properly. A tight pectoralis minor can keep your shoulder blade from tipping backward the way it is supposed to. Any of these cases, can adversely affect the movement of your GH joint, leading to impingement or other painful conditions of the shoulder.
Other things can cause shoulder pain. One of the more common ones is a “hooked acromion.” This is where part of the acromion (the bone that the tendon passes under), bulges downward, making the subacromial space smaller. Traditionally, this was thought to be genetic. Some recent research has suggested that it might be something that develops secondarily to other shoulder pathology. Either way, it is believed to increase the likelihood that your supraspinatus tendon will get irritated.
Any of these three conditions can produce shoulder pain. The most common area of pain is the front and the outside of your shoulder. It may also spread down the outside of your arm to your elbow and occasionally even to your wrist. Pain may be worse with work or sports activities, or when you lift your arm or lower it from a lifted position. Pain may be constant and aching, or it may be sudden and sharp with lifting overhead, reaching behind your back or other specific movements. It may interfere with sleeping.
Myofascial pain is one of the most common causes of shoulder pain that I see in my clinic. It is pain is pain referred from muscles and the fascia – the “shrink wrap” around your muscles. Referred pain is pain that originates in one place, but is felt in another. Referred pain is often coming from “Trigger Points.”
Trigger points are sore spots in tight bands in your muscles. Normally, they shouldn’t be there. Injury, infections, stress, over training and about a hundred other things can cause them to form. They’re different from regular tight muscles. Trigger points are basically little inflammation factories. What’s even weirder, trigger points can cause pain and other symptoms in totally different parts of the body – away from where the real problem is.
Several studies have shown that the rotator cuff muscles have trigger points in the majority of patients with impingement syndrome. The muscles can form trigger points in the absence of impingement, too. What’s more, neck muscles like the scalenes, the pectoral muscles of the chest and the biceps muscle of the arm can also cause shoulder pain.
If you’ve been suffering from shoulder pain, you may want to contact a qualified healthcare practitioner, like a sports acupuncturist. The good news is that shoulder pain often responds well to conservative treatment.
When you come in for your appointment, we’ll examine your your shoulder. We’ll see how it is moving and see what muscles might not be working properly. We’ll screen for more serious problems and look for trigger points that may be referring to your shoulder or causing muscles to “shut down”.
The techniques that we specialize in and teach are unique. While most traditional acupuncture styles focus on balancing out the body’s organ systems, and focusing on overall health, modern Orthopedic Acupuncture specifically targets the muscles, joints, and the nerve pathways that affect them. The goal is to restore normal, pain-free movement and get you back to doing what you love!
The Trigger points and muscle imbalances that often underlie shoulder pain usually respond well to the dry needling, orthopedic acupuncture and tuina soft tissue therapies that we specialize in. If you think you may be suffering from Give us a call at (315) 935-5700 to schedule your appointment today!