Glenohumeral arthritis is the breakdown of cartilage in the main ball-and-socket joint of your shoulder, where the upper arm bone (humerus) meets the shallow cup of the shoulder blade (glenoid). It affects 16% to 20% of middle-aged and older adults, making it one of the more common causes of chronic shoulder pain and stiffness. Unlike arthritis in weight-bearing joints like the knee or hip, shoulder arthritis tends to get less attention, but it can be just as disruptive to daily life.
How the Joint Breaks Down
Your shoulder joint is lined with a smooth layer of cartilage that lets the ball of the humerus glide against the glenoid socket with almost no friction. In glenohumeral arthritis, that cartilage wears away irreversibly. The bone underneath responds by thickening and forming small bony growths called osteophytes along the joint edges. Fluid-filled cysts can also develop in the bone beneath the worn cartilage.
The wear pattern depends on the type of arthritis. In standard osteoarthritis, the cartilage on the humeral head erodes in a central “bald spot” pattern, often surrounded by a ring of remaining cartilage and osteophytes. On the glenoid side, the wear tends to be concentrated toward the back of the socket, which can gradually push the humeral head out of its centered position. In inflammatory arthritis (like rheumatoid arthritis), the destruction is more even, stripping cartilage uniformly across both joint surfaces.
Types and Causes
Primary osteoarthritis is the most common form. It develops gradually with age and use, without a single identifiable trigger. But several other conditions can damage the glenohumeral joint in distinct ways.
- Post-traumatic arthritis develops after a shoulder fracture, dislocation, or other significant injury. The damage may accelerate cartilage loss years after the original event.
- Rheumatoid arthritis is an autoimmune condition that attacks the joint lining. On imaging, it looks different from osteoarthritis: the glenoid erodes toward the center rather than the back, and both shoulders are often affected.
- Rotator cuff tear arthropathy occurs when a large, chronic rotator cuff tear leaves the top of the humeral head unprotected. Without the cuff holding the ball centered in the socket, the humeral head migrates upward and grinds against the bony arch above it. The cartilage erodes from the top down rather than from the center out.
- Capsulorrhaphy arthropathy is a consequence of prior surgery for shoulder instability. If the joint capsule is tightened too much during repair, it forces the humeral head off-center, creating abnormal contact and accelerated wear.
- Avascular necrosis occurs when blood supply to the humeral head is disrupted, causing the bone and cartilage to collapse.
What It Feels Like
Pain is the earliest and most consistent symptom. It typically starts as a deep ache on the side of the shoulder that you notice only during activity. Over time, the pain becomes more frequent, eventually showing up at rest and during sleep. Many people find it increasingly hard to get comfortable at night because any position that puts pressure on the shoulder, or lets the arm shift, triggers pain.
Stiffness follows. You may first notice it as difficulty reaching behind your back or overhead. As the cartilage continues to thin, your range of motion shrinks enough to interfere with everyday tasks like getting dressed, washing your hair, or reaching a high shelf. Grinding, clicking, or popping sensations are also common, caused by roughened bone surfaces moving against each other where smooth cartilage used to be.
The condition progresses through a general pattern. Early on, the cartilage develops small cracks and you feel occasional stiffness with movement. In the moderate stage, cartilage begins to flake away and pain becomes more frequent. Stiffness sets in after any prolonged rest. In advanced stages, the cartilage is largely gone and bone contacts bone directly, which can make even small movements painful.
How It’s Diagnosed
Diagnosis starts with standard X-rays of the shoulder, typically taken from multiple angles. An image taken in the plane of the shoulder blade gives the clearest view of the joint space, which is the gap between the humeral head and the glenoid that represents your remaining cartilage thickness. As arthritis progresses, that gap narrows visibly.
X-rays also reveal the telltale bone changes: osteophytes along the joint margins, thickened bone beneath the cartilage surface, and cysts within the bone. The pattern of wear helps distinguish between types. Posterior glenoid erosion points toward primary osteoarthritis, while medial (inward) glenoid erosion with thinning of the surrounding soft tissues suggests rheumatoid arthritis. Superior migration of the humeral head on the image is a sign that the rotator cuff has failed, pointing toward cuff tear arthropathy.
MRI or CT scans are sometimes added to evaluate the rotator cuff, assess bone quality, or plan surgery, but X-rays alone are often enough to confirm the diagnosis and stage the disease.
Non-Surgical Treatment
There is no way to reverse cartilage loss once it has occurred, so treatment focuses on managing pain and preserving function for as long as possible. The American Academy of Orthopaedic Surgeons notes that physical therapy may benefit patients with glenohumeral osteoarthritis, particularly younger patients who aren’t good candidates for joint replacement (because the implant may not last their lifetime) and older patients who can’t undergo surgery due to other health conditions. The goal of therapy is to optimize mobility, strengthen the muscles around the shoulder, and minimize pain.
Anti-inflammatory medications and corticosteroid injections into the joint are commonly used alongside therapy. Injections can provide temporary relief by reducing inflammation inside the joint, though the effect is variable and tends to diminish with repeated use. Activity modification also plays a role: avoiding overhead movements or heavy lifting that provoke symptoms can slow the cycle of irritation and swelling.
When Surgery Becomes the Next Step
Joint replacement is the primary surgical option when conservative treatment no longer controls pain or maintains acceptable function. The type of replacement depends heavily on the condition of the rotator cuff.
If the rotator cuff is intact, an anatomic total shoulder replacement is the standard approach. This replaces the worn humeral head with a metal ball and resurfaces the glenoid socket with a plastic component, recreating the joint’s natural shape. If the rotator cuff is severely torn or absent, a reverse shoulder replacement is used instead. This design flips the ball-and-socket arrangement, placing the ball on the shoulder blade and the socket on the arm bone. The advantage is that it shifts the joint’s center of rotation in a way that allows the deltoid muscle, the large muscle on the outside of the shoulder, to take over the lifting work that the damaged rotator cuff can no longer perform.
Reverse shoulder replacement is also used for complex fractures of the upper arm bone and for cases where a prior shoulder replacement has failed.
Recovery After Shoulder Replacement
Full recovery from shoulder replacement takes several months. For the first few weeks, you’ll wear a sling to protect the repair. Most people can handle light daily tasks like getting dressed and simple chores within two to three weeks. Physical therapy typically begins a few weeks after surgery, though there is no universally agreed-upon schedule for how often sessions should occur or exactly when specific exercises should be introduced.
More demanding activities, including lifting heavy objects, sports, and intense workouts, are generally off-limits for several months. The timeline varies depending on the type of replacement, the quality of the bone and soft tissue, and how the healing progresses. The goal of rehabilitation is to gradually restore range of motion and strength while protecting the new joint components.