Shoulder Osteoarthritis

Shoulder osteoarthritis is the gradual wearing of the articular cartilage lining the glenohumeral joint — the ball-and-socket joint formed by the humeral head and the glenoid. It is less prevalent than hip or knee arthritis but causes significant pain and loss of motion. Primary (idiopathic) cases occur in older adults; secondary arthritis follows prior trauma, instability, rotator cuff tears, or inflammatory arthritis.

Posterior glenoid erosion — wearing down the back of the socket — is the characteristic pattern. This shifts the contact point of the ball posteriorly and worsens internal rotation loss.

Diffuse shoulder pain, progressive loss of internal rotation, and crepitus. Pain with passive rotation distinguishes glenohumeral arthritis from rotator cuff or acromial problems. X-rays show joint-space narrowing, subchondral sclerosis, and osteophytes. MRI evaluates glenoid bone loss, rotator cuff integrity, and fatty infiltration — critical for replacement planning.

1. Glenohumeral corticosteroid injection

   Intra-articular injection — effective for short-term pain relief.

2. PRP or viscosupplementation

   Options for patients wishing to delay surgery.

Progressive arthritis that significantly limits daily activities and does not respond to conservative management is the main indication for shoulder replacement.

External patient-education references and related OSI pages for additional background:

• Britannica — Osteoarthritis
• Britannica — Shoulder (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language