Another fun thing about middle age: Frozen shoulder

Formally known as “adhesive capsulitis," frozen shoulder is a painful condition where inflammation immobilizes the shoulder joint for months or even years. Doctors don’t know exactly what causes it. Unlike many other orthopedic problems, it’s not often triggered by overuse. Midlife women are especially prone to it.

At least 2% to 5% of people experience a frozen shoulder in their lives, according to studies, though the condition isn’t well-tracked. A 2022 study found a nearly 40% increase in frozen-shoulder diagnoses during the first year of the pandemic compared with the previous year. Some doctors say they are seeing more patients with frozen shoulder as the population ages and rates of diabetes and other health problems that can contribute to the condition increase.

Its propensity in midlife women, some doctors say, could be linked to declining estrogen levels during menopause, which hurts bones and muscles. Preliminary data suggests that hormone therapy could help prevent it.

What is it?

Frozen shoulder sometimes happens after an injury or surgery, but it often develops out of the blue. The condition occurs when the shoulder’s capsule becomes stiff and tight as adhesions—thick bands of tissue—develop.

Symptoms come in three stages: The “freezing" stage typically occurs first, with worsening pain that makes it hard to move your shoulder. During the second—or “frozen"—stage, pain lessens but stiffness remains, and your range of motion is limited. The final, “thawing" phase is when your range of motion returns to normal.

Frozen shoulder can last from three months to two years. On average, it lasts six to nine months, says Dr. Laura Moore, a sports-medicine surgeon at the Hospital for Special Surgery’s Women’s Sports Medicine Center. Treatments, aiming to reduce inflammation and improve pain and function, can vary, she says. Her go-to is a combination of steroid injections, an oral anti-inflammatory and physical therapy.

Frozen shoulder isn’t visible in an X-ray, but sometimes it’s visible on an MRI. Usually doctors diagnose it through a clinical exam.

The sooner you treat frozen shoulder, the better the outcome, says Dr. Jocelyn Wittstein, a professor at Duke University’s Department of Orthopaedic Surgery. If you catch a case in which the shoulder is very inflamed but not yet superstiff—usually within the first three months—a corticosteroid injection can reverse it. Starting treatments after the shoulder is very frozen isn’t as effective, she says. In rare cases, people need surgery.

Who gets it?

Frozen shoulder overwhelmingly affects midlife women. People with health problems associated with big changes in hormones, such as Type 2 diabetes and thyroid disorders, are also more at risk, doctors say. So are people with nerve issues, those who have had neck surgery or stroke, and people with Parkinson’s disease, says Moore.

Shoulder injuries can occur when a vaccine is administered incorrectly, doctors say. Occasionally that injury can trigger frozen shoulder, but such cases resolve more quickly than typical ones.

People often confuse frozen shoulder with other orthopedic problems, particularly rotator cuff tears or injuries, says Moore. It can also be mistaken for a shoulder impingement, tendinitis and osteoarthritis.

The hallmark feature of frozen shoulder is stiffness, while people with rotator cuff injuries can generally raise their arms without getting that feeling of hitting a wall, says Dr. Quin Throckmorton, a professor of shoulder and elbow surgery and vice chief of staff at the University of Tennessee-Campbell Clinic.

Why women at midlife?

Dr. Anne Ford, an obstetrician and gynecologist at Duke and division chief of Duke Women’s Health Raleigh, commonly asks her middle-aged female patients if they have joint issues. She estimates up to 20% of her perimenopausal and menopausal patients say they do—including frozen shoulder.

Estrogen receptors are present throughout the body, and estrogen has an anti-inflammatory effect, Wittstein says. So when women’s estrogen levels plummet during the menopause transition, that weakens the musculoskeletal system, leading to bone and muscle issues, she says.

In a study, Ford and Wittstein found that women who didn’t use hormone therapy—typically estrogen and progesterone supplementation—were twice as likely to develop frozen shoulder. But because the raw numbers of women taking hormone therapy were so small compared with the number who didn’t, the finding didn’t quite reach statistical significance.

Now, the doctors are working on a registry that they hope to use to do a larger study.

Adrianna Berlin, a 45-year-old in Grand Rapids, Mich., says she started experiencing perimenopausal symptoms earlier this year. But when she started feeling pain in her shoulder, she chalked it up to gym workouts.

She started using hormone therapy to help with such perimenopausal symptoms as night sweats and irritability. Three weeks later she says her shoulder problems went away. She had a lapse in her medication once, and noticed that her shoulder started acting up again.

“The pain in my shoulder is gone when I’m back on my medication constantly," she says. “How am I supposed to know that this is perimenopause?"

Write to Sumathi Reddy at Sumathi.Reddy@wsj.com