Tendon inflammation, instability, fracture and arthritis are main causes of shoulder pain, states the American Academy of Orthopaedic Surgeons. Tumors, infection and nerve-related issues are less common causes. Rotator cuff tendinitis, which is an inflammation of the tendons, is the most common cause of shoulder pain, according to Healthline.
Excessive use of the shoulder or aging can cause painful inflammation of the tendons in the shoulder, explains the AAOS. The tendons may also tear due to impact or injury. Bursitis, which is inflammation of the fluid-filled sacs cushioning the shoulder joint, may also occur with overuse. If the top of the shoulder blade presses on the rotator cuff tendons and the bursa, creating a condition known as impingement, an individual may experience pain and limited range of motion.
A sudden injury or overuse can cause the upper arm bone to become dislocated from the socket, a condition that is painful, indicates the AAOS. If this occurs repeatedly, the adjacent muscles, tendons and ligaments loosen or tear, causing additional pain and movement issues. Motor vehicle accidents, sports injuries and falls can cause fractures of the collarbone, shoulder blade or upper arm, resulting in shoulder pain, swelling and bruising.
Osteoarthritis may develop in the shoulder due to injury or age, according to the AAOS. Sometimes, it develops slowly and becomes more intense as time passes. Patients can restrict shoulder movement to avoid pain, but this potentially causes surrounding tissues to tighten or stiffen. This leads to additional pain and restricted movement known as frozen shoulder, advises Healthline.