The shoulder is a very strong and flexible joint; however, it requires considerable support from surrounding muscles and tendons.

The shoulder requires, and therefore is built for, a large degree of flexibility. This flexibility allows us to reach objects overhead as well as behind our backs. The design cost of this increased flexibility is that the shoulder is not as stable as some of the other joints, such as the hip.

It is therefore not surprising that the shoulder is prone to injury, dislocation and separation, and that many people have shoulder pain due arthritis as well as soft-tissue problems, such as shoulder bursitis and rotator cuff injuries.

Shoulder Joint Anatomy and Pain

The shoulder is located where the arm meets the torso and is comprised of and functions with the following basic components:

• Shoulder bones. The bones must maintain their strength and smooth surface in order to move easily against each other. Development of boney growths, called osteophytes or bone spurs, may impede this function and cause pain.
• Shoulder cartilage. The cartilage must be smooth and strong to allow the bones to move against each other without too much friction.
• Shoulder muscles. Muscles both support joints and enable movement.
• Shoulder ligaments and tendons. The multiple ligaments and tendons around the shoulder must be strong to bind the shoulder joints together and encapsulate them in a tough but flexible structure.

Shoulder problems occur when any one of these components starts to degenerate or is in some way compromised or irritated. The root cause is often overuse (which often comes with age), dislocation, or an accident, such as using the arms to break a fall, impacting the shoulder joint.

While the shoulder is less prone to osteoarthritis than weight-bearing joints, such as the hip or knee, shoulder arthritis that impacts function of the shoulder joint is still relatively common.

Moreover, because the shoulder is involved in most arm and hand movements, shoulder arthritis pain can severely impede one’s ability to function in everyday activities and the pain can be debilitating.