Shoulder Arthritis

Shoulder arthritis happens when one or both of the main shoulder joints begin to wear down. The shoulder has two key joints: the ball-and-socket joint, where the top of the arm bone fits into the shoulder blade, and the acromioclavicular (AC) joint, where the collarbone meets the shoulder blade. In a healthy shoulder, cartilage cushions these joints so the bones glide smoothly when you move. Over time, this cartilage can break down, causing the bones to rub together. This leads to pain, stiffness, and a loss of mobility. Different forms of arthritis may affect the shoulder, including osteoarthritis from natural wear and tear, rheumatoid arthritis from inflammation, arthritis that develops after an injury, and arthritis linked to long-term rotator cuff problems.

The development of shoulder arthritis can be influenced by several causes and risk factors. Often, more than one factor is involved.

• Osteoarthritis: This is the most common type, caused by “wear and tear” over time. Cartilage wears away, leading to pain, stiffness, and swelling. Most often affects people in middle age and older.
• Rheumatoid arthritis: An autoimmune disease where the immune system attacks the joints, causing inflammation and damage. Often affects both shoulders and other joints.
• Post-traumatic arthritis: Trauma or injury, including fractures and dislocations, may damage cartilage or joint surfaces directly, increasing the risk of arthritis later.
• Rotator cuff tear arthropathy: Rotator cuff tear arthropathy may develop when the rotator cuff tendons are seriously injured or torn, altering joint mechanics and accelerating wear. Inflammatory arthritis such as rheumatoid arthritis occurs when the body’s immune system attacks its own joint tissues, leading to swelling, cartilage damage, and pain.
• Avascular necrosis (osteonecrosis): Avascular necrosis, or osteonecrosis, is a condition where loss of blood supply to bones in the shoulder leads to bone collapse and secondary cartilage damage. Can result from injury, certain medications, or heavy alcohol use.

Symptoms of shoulder arthritis vary in severity, depending on how advanced the joint degeneration is.

• Pain is often the first symptom. It may occur during activity, such as lifting, reaching, or overhead motion, and as the condition worsens, pain may also occur at rest.
• Night pain is frequent because finding a comfortable sleeping position can be difficult.
• Stiffness and reduced range of motion are also common, making movements such as lifting the arm, reaching overhead, or reaching behind the back harder. Everyday tasks like dressing or combing hair can become more difficult.
• Grinding, clicking, or popping sounds, known as crepitus, occur when the normally smooth surfaces of the joint are roughened or cartilage is lost. Movement becomes irregular.
• Weakness may develop, especially when using the arm in certain directions, as surrounding muscles or the rotator cuff are affected. Many people also notice difficulty with sleep since lying on the shoulder can worsen pain and stiffness.

The shoulder joint is one of the most mobile joints in the body. This wide range of motion makes it more vulnerable to cartilage wear compared to joints that move less. Over years of lifting, reaching, carrying, and overhead motion, the protective cartilage that cushions the ball-and-socket or acromioclavicular joint slowly thins. Once cartilage breaks down, the bones begin to rub directly against each other, which causes the pain, stiffness, and grinding often associated with shoulder arthritis.

Certain risk factors increase the likelihood of developing shoulder arthritis.

• Age is a significant factor, as most people begin to develop symptoms in middle age or later.
• Family history can also play a role, especially with inherited tendencies toward cartilage weakness or inflammatory disease.
• Prior shoulder injuries, surgeries, or repeated stress from activities such as sports or occupations that require overhead motion raise the risk.
• Obesity contributes indirectly by increasing systemic inflammation and joint stress, even though the shoulder is not a weight-bearing joint like the knee or hip.

Diagnosing shoulder arthritis typically involves several steps. At Ortho Illinois, specialists begin with a thorough medical history to understand when symptoms began, how pain behaves, whether there were prior injuries, and how daily activities are affected.

A physical examination follows, during which the physician checks for tenderness, swelling, reduced range of motion, strength, and crepitus. The shoulder is compared to the opposite side, and both the AC and glenohumeral joints are evaluated.

Imaging tests are an important part of diagnosis. X-rays are the first step and can reveal joint space narrowing, bone spurs, changes in bone shape, and misalignment. MRI scans are helpful if soft tissues like the rotator cuff are suspected to be involved, and CT scans may be ordered for more detailed bone evaluation or surgical planning. If inflammatory arthritis is suspected, lab tests may be used to identify markers of inflammation or autoimmunity, and collaboration with rheumatology may be recommended.

Catching shoulder arthritis early helps slow progression, reduce pain, and preserve function. Early non-surgical treatments such as physical therapy, activity modification, rehabilitative exercises, and anti-inflammatory medications are more effective when joint damage is still moderate rather than severe. Delaying care can lead to worsening pain, more limited motion, and the need for more invasive interventions.

Treatment will depend on severity. Mild to moderate cases often respond to non-surgical care such as rest, ice or heat, physical therapy, anti-inflammatory medications, and sometimes corticosteroid injections. More advanced cases may require surgical treatment, which can include joint debridement, partial or total shoulder replacement, or a reverse shoulder replacement if the rotator cuff is compromised.