Ever have a doctor tell you, you have an impingement in your shoulder? And another says you that it’s bursitis and tendonitis…maybe some arthritis, while another say you have a rotator cuff tear? What exactly is going on? What does it mean by “impingement”?
A crash course on the anatomy of the shoulder would help you fully understand this term. The shoulder is actually made up of 3 bones: the clavicle (collar bone), scapula (shoulder blade), and the humerus (upper arm bone). These bones actually form not just one or 2 joints but 4 all in all. Don’t want to get too technical here, but throwing in some pretty long words is inevitable; the joints are:
- Acromioclavicular (between the collarbone and the upper portion of the shoulder blade)
- Sternoclavicular (between the breastbone and collarbone)
- Glenohumeral (this is the actual shoulder joint, between the socket formed by the shoulder blade and the ball in the upper portion of the arm)
- Scapulothoracic (between the shoulder blade and the ribcage).
Another noteworthy area in the shoulder is the subacromial space (the area between the uppermost portion of the shoulder blade and the tip of the clavicle). Structures in this area include: a bursa and 2 tendons— that of the supraspinatus and long head of the biceps. Bridging this space at the top is an arch (coracoacromial ligament).
The shoulder is the most mobile joint in the body. The ball formed by the upper arm bone is usually larger than the socket formed by the shoulder blade (the socket only covers ¾ of it). The upper arm bone is basically just suspended, but not too worry, the famous (or rather infamous), rotator cuff stabilizes it.
The rotator cuff is a group of muscles (four in all) that pushes the ball formed by the upper arm bone into the socket and clears the subacromial space. Without these muscles, moving your arm overhead will result in constant abutment against the “bridge” (coracoacromial ligament) causing what we call “impingement”. Impingement causes inflammation of structures in this area— thus you can also have bursitis and tendinitis. If you already have an impingement and continue to use your arm, it further weakens your tendon like the fraying of a rope, going from a partial tear to a complete tear. So what would cause impingement?
Factors:
- Irregularities in the bones that you maybe born with.
- Weakness in the rotator cuff due to degeneration and arthritis in the joint — yea, we’ll blame age again.
- Overuse, repetitive activities (playing tennis, painting, etc), and forceful movements (throwing a baseball).
You can’t take impingement lightly, if ever you raise your arm overhead and your shoulder hurts, don’t ignore it. Medical and Physical Therapy management is your first line of defense.