Arthritis

Overview
Shoulder arthritis is a condition in which the normally smooth cartilage covering the ball and socket of the shoulder joint is lost due to disease, wear and tear, injury, or surgical misadventure.  The result is that there is bone one bone rubbing between these two joint surfaces.

Causes
Degeneration (wear and tear)
Osteoarthritis
Rheumatoid arthritis
Rotator cuff tears
Surgery for recurrent dislocations

Symptoms
Pain and stiffness in the shoulder

Diagnosis
Physical examination and medical history consultation
X-rays

Treatment
Physical therapy
Surgery

Source: https://orthop.washington.edu/