Overview
Shoulder arthritis occurs when the articular cartilage—the smooth surface covering the ends of the bones—gradually wears away. I often explain arthritis using the example of a tile floor. The concrete slab represents the bone, while the smooth ceramic tiles represent the articular cartilage. As long as the tiles remain smooth and intact, everything glides effortlessly. Once the tiles crack, chip, or wear away, the smooth surface is lost. Arthritis is damage to the "tiles," not the concrete underneath.
The shoulder has two smooth cartilage surfaces that normally glide against one another—one covering the ball (humeral head) and the other covering the socket (glenoid). When either or both surfaces become damaged, arthritis develops. The most common type is degenerative arthritis (osteoarthritis). Other forms include rheumatoid arthritis and post-traumatic arthritis. Although the causes differ, the end result is the same—the smooth cartilage surface becomes damaged.
Presentation
Symptoms usually develop gradually over many years. Patients commonly experience increasing pain, night pain, pain even at rest, progressive stiffness, and grinding or catching within the shoulder. Unlike most rotator cuff problems, strength is often well preserved while loss of motion becomes the primary limitation.
Conservative Treatment
Treatment may include activity modification, anti-inflammatory medications, and therapy focused on maintaining shoulder range of motion. The cornerstone of non-operative treatment is a corticosteroid injection into the glenohumeral joint, which often provides significant pain relief but does not restore cartilage or improve motion. Unlike a repairable rotator cuff tear, an arthritic shoulder is not "on the clock." Treatment is based primarily on pain, stiffness, function, and quality of life.
Surgical Treatment
When pain and loss of function become unacceptable, shoulder arthroplasty is an excellent option. The damaged joint surfaces are removed and replaced with smooth artificial surfaces. The type of shoulder arthroplasty depends primarily on the condition of the rotator cuff.
Patients with a healthy, functioning rotator cuff are candidates for an anatomic total shoulder arthroplasty, which recreates the normal anatomy of the shoulder. Patients with an irreparable rotator cuff tear require a reverse total shoulder arthroplasty. In this procedure, the ball is placed on the socket (glenoid) side and the socket is placed on the arm (humeral) side, placing the shoulder in a position where it can function well without a normal rotator cuff. The procedure generally takes 45–60 minutes, and most patients return home the same day.
Recovery
Patients begin light use of the arm in front of the body immediately after surgery while following lifting restrictions. Typical milestones include sling removal at approximately six weeks, moderate activities at three months, and maximum recovery by six months.
Most patients experience tremendous pain relief following shoulder arthroplasty. In addition, most regain significant shoulder motion and return to many daily activities that had become painful or impossible before surgery.