Shoulder Osteoarthritis

Shoulder osteoarthritis involves the progressive degeneration of the smooth articular cartilage lining the humeral head (ball) and the glenoid cavity (socket). As the cartilage wears down, friction between exposed bone surfaces results in mechanical pain, secondary joint inflammation, and peripheral osteophyte (bone spur) formation.

Primary shoulder osteoarthritis is commonly associated with aging and genetic predisposition. Secondary causes include post-traumatic damage (prior fractures or recurrent dislocations), chronic massive rotator cuff tears leading to cuff tear arthropathy, avascular necrosis (AVN) of the humeral head, and systemic inflammatory arthritis such as rheumatoid arthritis.

The most frequent symptoms include deep, aching joint pain exacerbated by activity, prominent night pain that disturbs sleep when lying on the affected side, progressive stiffness with restricted range of motion (especially external rotation and overhead elevation), and palpable or audible crepitus (grinding/clicking sensations).

In rotator cuff tendinopathy or impingement, pain typically occurs during specific active arcs of motion, while passive range of motion (when the clinician moves the arm) is largely preserved. In glenohumeral osteoarthritis, both active and passive motion are progressively restricted due to mechanical osteophytes and capsular contracture.

Diagnosis begins with a focused clinical history and physical examination. Standard plain radiographs (true AP/Grashey, axillary, and scapular Y views) remain the gold standard, demonstrating joint space narrowing, subchondral sclerosis, cyst formation, and inferior humeral osteophytes. CT scans are utilized for surgical planning to evaluate glenoid bone loss and version, while MRI evaluates the integrity of the rotator cuff muscles and tendons.

First-line conservative strategies include activity modification (avoiding repetitive overhead loading), targeted physical therapy focusing on capsular stretching and periscapular stabilization, non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen, thermal modalities (ice/heat), and intra-articular injections.

Intra-articular injections (such as corticosteroids, hyaluronic acid/viscosupplementation, or platelet-rich plasma [PRP]) do not reverse cartilage loss or restore worn cartilage. Instead, they provide targeted symptomatic pain relief and decrease synovitis, opening a therapeutic window for physical rehabilitation and improving daily function.

Surgical intervention is indicated when conservative measures have failed to control persistent, severe pain (particularly intractable nocturnal pain), and when structural joint destruction significantly impairs basic activities of daily living.

Anatomic Total Shoulder Arthroplasty (TSA) replicates native anatomy by replacing the ball with a metal prosthetic head and the socket with a plastic glenoid component; it requires a functioning, intact rotator cuff. Reverse Total Shoulder Arthroplasty (rTSA) reverses the ball and socket configuration (placing a spherical glenosphere on the socket and a concave cup on the humerus); this design allows the deltoid muscle to lift the arm when the rotator cuff is deficient, torn, or severely compromised.

Patients are advised to keep objects close to the body when lifting, avoid sudden heavy ballistic loading or repetitive overhead strain, maintain daily low-impact range-of-motion exercises (such as pendulum or pulley stretches), optimize sleeping posture using supporting pillows, and maintain good thoracic and cervical spine alignment.