Dear Doctor: One of the moms in our car pool had to drop out because she has a frozen shoulder. I’ve never heard of that. What is it, and how did she get it?
Dear Reader: Frozen shoulder, also known as adhesive capsulitis, is a common and painful condition in which the connective tissues around the shoulder joint gradually become thickened and inflamed. It’s more common in women than men, and it more commonly occurs in people from ages 40 to 60. With a frozen shoulder, previously simple activities like raising your arms to slip into a T-shirt or even reaching up to scratch your head become very difficult.
To understand the condition, let’s start with the shoulder joint itself. It’s a ball-and-socket joint, which means that the rounded head of the humerus, which is the upper arm bone, fits into a cuplike structure located on the scapula, or shoulder blade. Cartilage, which is smooth and elastic, covers the surfaces of the bones where they meet. It acts as a shock absorber, and its sleek surface helps to reduce friction and smooth movement. Meanwhile, strong ligaments that attach to the “ball” of the humerus and to the shallow “socket” on the scapula hold the parts of the shoulder joint in place. Taken together, this allows for a wide range of motion. In fact, the ball-and-socket joint offers the most freedom of movement of any type of joint in the body.
When inflammation causes the connective tissues within the shoulder joint to become thick and stiff, the capsule tightens. In some cases, scar tissue forms, which further limits range of motion. All of this makes any kind of movement within the joint, whether active or passive, both difficult and painful.
Frozen shoulder can develop when injury, trauma or surgery have forced long-term immobility. It is also seen more often in people at risk of developing diabetes, and those with chronic inflammatory arthritis. The condition begins with localized discomfort or pain, which gradually increases over time. It can take from two to 10 months for a frozen shoulder to develop. During the “frozen” stage of the condition, which can also last for months, the joint becomes difficult, if not impossible, to move. The good news is that during this time, pain from the condition may decrease. Eventually, range of motion begins to return to the joint.
In order to eliminate other potential causes, imaging tests like an MRI or an X-ray may also be used. Treatment focuses on alleviating pain and recovering range of motion. This entails the use of various anti-inflammatory medications, and possibly injections of corticosteroids into the joint capsule. Patients are also taught exercises to stretch the joint capsule, and when recovery begins, strengthening exercises. Infrequently, surgery may be required. Most cases of frozen shoulder resolve within a year or two.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.
