By: Rachel Herrmann, PT, DPT
The shoulder is a complex region of the body made up of 3 joints, 4 muscles of the rotator cuff and over 10 other muscles that attach around the bones/joints that make up the shoulder. This means there has to be a lot of body parts in good working condition in order to have a healthy and happy shoulder.
One common shoulder issue is called impingement. This is when the muscles of the rotator cuff become subjected to repeated pinching in between the rounded head of the humerus bone and the acromion process, a bony prominence from the shoulder blade that forms a roof over top of the ball and socket joint. Initially, this pinching may only be a discomfort or may not even produce pain, but with repetition over time, the rotator cuff muscles will become inflamed. Further repetitive pinching, or impingement of the rotator cuff can gradually lead to small or even large tears of the rotator cuff muscles.
So, why does impingement occur? There can be a few contributing factors to this condition.
- Repetitive and/or prolonged overhead movements can place the shoulder in a position where it is more likely to be impinged, such as when swimming, hanging holiday decorations, painting tall walls or ceilings.
- Posture will also impact the positioning of the shoulder blade and therefore the positioning of the bony roof of the shoulder. If the bony roof hangs forward over the shoulder more than it should, any upward reaching position would be more likely to produce impingement.
- The underlying anatomy of one’s shoulder can also affect the likelihood of impingement. Some people have more rounded acromion processes and some have bone spurs or other degenerative changes that can make impingement and rotator cuff muscle irritation more likely.
- Another factor contributing to impingement is the strength and control of the rotator cuff muscles. The role of the rotator cuff muscles is to not only help move the shoulder in various directions, but also to help provide stability of the ball and socket joint. The socket part of the joint is actually fairly shallow. So as the arm is reaching upward, if the rotator cuff does not have adequate strength or control, the ball end of the arm can slip upward resulting in impingement.
- Additionally, if the muscles around the shoulder blade are weak or do not coordinate well with the rest of the shoulder, then you are going to end up with an unstable foundation on which the rotator cuff muscles work. This muscle weakness or incoordination can also contribute to impingement.
The good news is that physical therapy can help. A physical therapist is trained to be able to determine if you are experiencing impingement related shoulder pain and to assess posture, flexibility, muscle strength, stability, coordination, joint mobility, and muscle tone in order to determine which factors are contributing to this impingement. After that assessment, a physical therapist can then help teach you how to address the underlying issues contributing to your pain in order to help you be able to move and use your arm without further irritation of the rotator cuff muscles. This is definitely a condition that in the majority of cases can get better, but is best treated sooner rather than later so that the impingement does not lead to rotator cuff tears.
