Think of your rotator cuff tendons as a rope that has to glide through a small opening. The smaller the opening the more the friction on the rope. This continuous friction will ultimately lead to damage of the structure of the rope. Eventually, the rope will start to fray and one day it could tear off completely. That is how shoulder impingement syndrome works as well.
Shoulder impingement syndrome can be described as: the compression of soft tissue (rope), against the subacromial arch (opening). There are two ways that subacromial impingement could happen; the subacromial space could get smaller or the soft tissue underneath it could get bigger. Or both of these things could happen at the same time. Either way, it prevents soft tissue like your rotator cuff tendons to glide freely and causes pain, inflammation, swelling and impingement.
Shoulder impingement isn’t actually a diagnosis
The term impingement actually describes why you feel pain. Shoulder impingement syndrome describes a few different conditions that can be classified under it namely: subacromial bursitis, rotator cuff tendon calcification, rotator cuff tendinopathy, rotator cuff tears or even degeneration. These conditions have symptoms that overlap and all of them can cause impingement, but ultimately it is separate diagnoses. That is why it is so important to diagnose the real underlying reason for your shoulder impingement, because it will affect your treatment.
Subacromial impingement can be classified into external and internal impingement.
External Impingement (smaller space)
• Primary External Subacromial Impingement happens when there is a change in the structure of the surrounding bones which in turn narrows the subacromial opening. It is an abnormality that you can be born with or it could happen with time. Examples of this is: abnormal shape of the acromion or clavicle or an osteophyte (bone spur) growing into the space.
• Secondary External Subacromial Impingement is related to abnormal movement of your shoulder joint. With muscle weakness, instability or muscle imbalance your shoulder joint won’t be kept in a safe, neutral position. Instead, it might be pulled in a certain direction and when you move your arm it forcibly decreases the subacromial space.
Internal Impingement (increased soft tissue size)
• This type of impingement is caused by rotator cuff tendons against the upper side of the humerus and shoulder joint due to increased size of the tendons. Overuse, swelling or scar tissue in the these tendons could cause them to increase in size. The same way muscles get bigger with exercise, tendons get bigger when they work harder. However, the structure of the tendon gets damaged with overuse. In an attempt to heal a tendon, your body produces more new collagen cells. This leads to tendon thickening, loss of flexibility and ultimately weakening of the collagen structure. If the load isn’t reduced there is more and more damage to the tendon until it eventually fails and tears.
Compensating leads to more problems
With subacromial impingement, you’ll want to rest your arm. Because without movement, there’s no impingement. However, with more rest, your rotator cuff muscles get weak and your body compensates by using other muscles like your deltoid, biceps, trapezius or latissimus dorsi. An example of this would be when you lift your arm up to put on a shirt. If it is too painful, you’ll find ways to cheat. By tensing your neck muscles or bending sideways with your upper body, you’ll be able to lift your arm with more ease. However, these muscles will also become overworked and sore with time. Once you reach that point, your movement becomes very limited and tasks which should be easy daily things, becomes impossible to do. Combing your hair, drinking a cup of coffee, working behind a desk or even simply driving your car. It’s a vicious cycle that you don’t want to get stuck in.
Don’t let your shoulder impingement syndrome get to this point. You won’t be able to lift a finger