How does supraspinatus tendinitis happen?
The shoulder joint
The shoulder or glenohumeral joint (GHJ) needs to move in harmony with three other joints to allow full movement. These joints are the:
- Sternoclavicular (SC) joint between the collarbone (clavicle) and breastbone (sternum)
- Acromioclavicular (AC) joint between the collarbone and acromion (part of the shoulder blade)
- The scapula (shoulder blade) also glides on the ribcage to allow free movement of the shoulder joint.
The shoulder is a ball & socket joint. The glenoid, which is part of the shoulder-blade, forms the socket, and the head of the humerus of the upper arm, forms the ball. The socket is very shallow, especially when compared to the hip joint. This allows a lot of movement, but very little stability. Luckily the shoulder joint has help from muscles and ligaments that assist in the stability of the joint.
Harmonious movement of all of these joints allows you to reach overhead. If one joint is stuck it will affect the movement of the others, like one member of an orchestra that plays out of time. More strain will then be placed on the other musicians, or in our case, the other joints. Let’s say the shoulder blade isn’t moving optimally on the ribcage. This may be due to weakness of certain muscles and will limit the lift from the acromioclavicular joint when you elevate your arm. Now the head of the humerus hits the roof of the acromion and pinches the poor supraspinatus tendon in between the bone surface, ouch! Supraspinatus tendon impingement most definitely cause significant tendon pain.
When the load is higher than the tendon junction can tolerate small tears occur. Excessive load in a once off traumatic event, like lifting a too heavy weight during your training. Or small tears accumulate over a longer period of time from repetitive overuse, like perfecting your tennis serve.
Once there are small tears in the tendon inflammation forms around the injured area to aid its recovery. Inflammation is the body’s way of getting all the healing agents where they are needed. Once healing has taken place, inflammation should settle. Repetitive injury sustains this inflammatory reaction which then initiates the tendinopathy continuum, explained later. Insufficient rest or poor movement patterns worsen the problem.
If you get caught in this cycle of exercising or doing an aggravating activity, experience shoulder pain, rest, less pain, go back to participating, you unconsciously create new compensatory movement patterns to adapt. This is the body’s way of avoiding pain. These “new” movements contribute and sustain your supraspinatus tendinitis.