Shoulder Arthritis

The shoulder is a ball-and-socket joint where the rounded head of the upper arm bone (humerus) meets the shallow socket of the shoulder blade (glenoid). A smooth layer of cartilage covers both surfaces, allowing them to glide against each other without friction. Shoulder arthritis occurs when this cartilage breaks down, causing the bones to rub together, which produces pain, grinding, and stiffness that can significantly limit everyday activities.

Unlike the hip or knee, the shoulder is not a weight-bearing joint, which is why arthritis here is often tolerated for years before it is diagnosed. Patients frequently notice the loss of motion, especially reaching behind the back, before they identify the pain as arthritis.

The type of arthritis present shapes the entire treatment plan, particularly the choice of implant if a replacement eventually becomes necessary.

• Osteoarthritis: The most common form, this “wear and tear” arthritis develops gradually over time. The socket typically wears unevenly, most often toward the back, which is an important consideration in surgical planning.
• Post-traumatic arthritis: Arthritis that follows a prior shoulder injury or surgery, including fractures, dislocations, and instability procedures. It often affects younger patients than osteoarthritis does.
• Rheumatoid and inflammatory arthritis: Autoimmune conditions that attack the joint lining, frequently affecting both shoulders and often accompanied by rotator cuff deficiency and bone loss.
• Rotator cuff tear arthropathy: A distinct pattern in which a long-standing, massive rotator cuff tear allows the ball of the joint to migrate upward and erode against the underside of the shoulder blade. Because the cuff is no longer functioning, these patients often cannot lift the arm at all, and their treatment differs fundamentally from that of osteoarthritis with an intact cuff.
• Avascular necrosis: Loss of blood supply to the humeral head, which causes the bone beneath the cartilage to collapse. It can follow fracture, steroid use, or certain medical conditions.

Most shoulder arthritis develops gradually as cartilage wears down with age and use. Factors that increase the risk include prior shoulder fracture or dislocation, previous shoulder surgery, a long-standing rotator cuff tear, heavy overhead work or lifting over many years, inflammatory joint disease, and a family history of arthritis. Patients who had shoulder instability surgery decades ago are a particular group at risk, as certain older procedures altered shoulder mechanics in ways that accelerate wear.

Shoulder arthritis typically develops gradually, and symptoms often worsen over time without treatment. Dr. Rynecki Baker encourages patients not to dismiss early symptoms, as timely evaluation opens the door to treatments that preserve motion and quality of life. Common symptoms include:

• Deep, aching pain: Usually felt within the shoulder and upper arm, worse with activity and often present at rest or waking patients from sleep in advanced cases.
• Stiffness and loss of motion: Difficulty reaching overhead, behind the back, or across the body. Loss of outward rotation is often the earliest sign.
• Grinding or clicking: A grinding or crunching sensation, called crepitus, as roughened joint surfaces move against each other.
• Weakness: Pain and stiffness make lifting and daily tasks progressively more difficult.
• Inability to lift the arm: A shoulder that shrugs rather than elevates, which suggests rotator cuff tear arthropathy.

Accurate diagnosis begins with a thorough evaluation by Dr. Rynecki Baker. She will take a detailed history, including prior injuries, surgeries, and any inflammatory joint conditions, and perform a physical examination assessing range of motion in each direction, strength, and the integrity of the rotator cuff. Distinguishing arthritis of the ball-and-socket joint from acromioclavicular joint arthritis, stiff shoulder, and rotator cuff disease is a central part of the evaluation, as these conditions frequently coexist and are commonly confused.

Imaging confirms the diagnosis and guides treatment: X-rays are the primary tool for diagnosing shoulder arthritis, revealing joint space narrowing, bone spur formation, and upward migration of the ball in cuff tear arthropathy. MRI is obtained when additional information is needed about the surrounding soft tissues, particularly the rotator cuff, which determines which type of replacement is appropriate. CT scan provides a detailed, three-dimensional picture of bone anatomy, including the pattern of socket wear and bone loss, and is used in planning shoulder replacement.

Shoulder arthritis is a progressive condition, and the decisions made about the timing and type of treatment have long-term consequences. The right operation depends on the state of the rotator cuff, the pattern of wear in the socket, and the patient’s age and demands. Dr. Rynecki Baker’s training at NYU Langone Health and Hospital for Special Surgery, her dedicated focus on shoulder surgery and sports medicine, and her published research mean patients are evaluated by a specialist with deep knowledge of shoulder mechanics and reconstruction.

Dr. Rynecki Baker approaches every patient with shoulder arthritis as an individual, taking the time to understand each person’s symptoms, goals, and lifestyle before recommending any course of treatment, and she is candid about when it makes sense to wait.