Frozen Shoulder and Thyroid Disease

It often starts with difficulty moving your shoulder or a dull, aching pain in your shoulder area. If these symptoms sound familiar, you could have adhesive capsulitis, a condition more commonly referred to as frozen shoulder. Though it's not clear why, frozen shoulder is more common in people with endocrine problems, including thyroid diseases.

The bones, ligaments, and tendons that make up the shoulder joint are wrapped in a capsule of connective tissue. Frozen shoulder occurs when this capsule thickens and becomes inflamed, causing it to contract and form scar tissue.

Having an endocrine condition such as diabetes or thyroid disease, including both hyperthyroidism and hypothyroidism, is a risk factor for frozen shoulder. And though the link between thyroid disease and frozen shoulder remains uncertain, research has revealed some possible connections with both hyperthyroidism and hypothyroidism.

A 2014 study concluded that hyperthyroid patients have 1.22 times the risk of developing adhesive capsulitis compared to the general population. The study followed 4,472 people with hyperthyroidism over seven years. Within that period,162 of them developed adhesive capsulitis.

The researchers speculated that these findings might be related to an inflammatory process— stimulated by the production of proteins known as cytokines—that is characteristic of both hyperthyroidism and adhesive capsulitis. Conceivably, one could trigger the other, or they could occur in tandem.

Another study evaluated 93 patients with frozen shoulder and 151 without the condition. Higher serum levels of thyroid-stimulating hormone (TSH), typically found in people with hypothyroidism, were also found in the participants with frozen shoulder.

Finally, it is known that muscle pain (myopathy) is common in both hypothyroidism and hyperthyroidism. Whether this is related to frozen shoulder specifically, however, is not clear.

Other risk factors or potential causes of frozen shoulder include:

• Having a shoulder injury, shoulder surgery, shoulder trauma, or an immobilized shoulder
• Having a surgery that immobilizes your shoulder, such as breast surgery or open heart surgery
• Hormonal changes, such as perimenopause and menopause
• Cervical disk disease of the neck

Frozen shoulder symptoms usually develop slowly over time and worsen gradually. Often, the condition begins with mild pain over the course of several months. It typically goes through three different stages, with different symptoms evident at each stage:

• Freezing stage: This is usually the most painful stage, with pain most severe in your outer shoulder area. In some cases, you may also have pain radiating down into your upper arm. Moving your shoulder can be painful, so daily activities that require you to lift your arm—such as brushing your hair or reaching something on a high shelf—can become difficult. You may have pain while sleeping as well. Your range of motion in the shoulder is also typically reduced.
• Frozen stage: During this stage, the range of motion of your shoulder is even more limited and your shoulder becomes stiffer. It can become increasingly difficult to lift up your arms or move your arms backward. Over time, the shoulder can become so stiff that it is almost impossible to move. You may notice a lessening of pain, however, as your shoulder becomes less mobile. 
• Thawing stage: You typically will have less pain at this point, and range of motion will improve over time.

Diagnosing frozen shoulder can be tricky because the main symptoms—pain and stiffness—are characteristic of numerous other conditions, including rotator cuff injuries. In fact, frozen shoulder is often misdiagnosed as a tear in the rotator cuff. Furthermore, people with frozen shoulder sometimes compensate for reduced shoulder joint movement by moving their shoulder blades and spine in certain ways, adding to the challenge of getting an accurate diagnosis.

Your doctor will likely inject your shoulder with a numbing medicine in order to assess your range of motion without causing pain. You will be asked to move your arm around in different ways; this is known as "active" range of motion. Your doctor may also manipulate your arm to determine what's known as passive range of motion. Frozen shoulder affects both.

Imaging tests, such as X-rays or magnetic resonance imaging (MRI), may also be done to rule out other problems.

Frozen shoulder usually resolves on its own over time, but this can involve several years of pain and restricted mobility until the shoulder returns to normal. In some cases, full range of motion in the shoulder never returns.

When frozen shoulder is identified and diagnosed early, a cortisone injection directly into the frozen joint can help restore range of motion and may help speed the healing time dramatically. Gentle stretching, as opposed to more aggressive physical therapy, is recommended to complement the effects of cortisone treatment.

In some cases, nonsteroidal anti-inflammatory drugs (NSAIDs) along with physical therapy and home exercises, can be effective. This approach may help to restore the range of motion and relieve pain, but it can take as long as a year to get full relief.

Surgery for frozen shoulder is the last resort but may be recommended if other options are not effective. Surgery—often performed arthroscopically—focuses on removing scar tissue and adhesions in the shoulder. Following surgery, a period of physical therapy is typically necessary to restore and maintain the range of motion in the shoulder.

There are a few promising newer options to consider for frozen shoulder as well. They include transcutaneous electrical stimulation (TENS), which has been shown to significantly increase range of motion. Low-power laser therapy and deep heating (diathermy treatment) with stretching may also provide relief.