Do you experience bone pain, especially when resting? This may be a symptom of bone marrow edema (BME) — fluid buildup in your bones — which can be associated with ankylosing spondylitis (AS).

This article will discuss what BME is, how it relates to AS, and the ways it’s treated. Knowing the signs and symptoms of BME can help you get treatment sooner and live a more comfortable life.

Types of Pain in Ankylosing Spondylitis

AS, also called radiographic axial spondyloarthritis or r-axSpA, is an autoimmune inflammatory condition that affects the spine’s joints and ligaments. The inflammation can cause many types of pain, especially pain and stiffness in the spine. In severe cases, this spinal inflammation can cause the bones or vertebrae in the lower spine to fuse (known as ankylosis or “bamboo spine”). Fusion limits mobility and range of flexibility (including when you breathe) and increases stiffness and pain in the part of the lower back called the lumbar spine.

In addition to the inflammatory back pain, which is the most frequent symptom of AS, people may experience pain in other joints, such as:

• Buttocks (sacroiliac joints)
• Shoulders
• Ankles
• Small joints of the hands or feet

They may also experience pain caused by:

• Inflammation of a tendon or entheses (where tendons or ligaments attach to bones), most frequently the Achilles tendon
• Swelling of the fingers, known as dactylitis (also called “sausage fingers”)
• Bone pain due to BME

Other types of pain connected to AS, which are felt in areas outside the joints, include:

• Uveitis (pain and redness of the eye)
• Inflammatory bowel disease (abdominal pain)

Bone pain from BME can be intense. One member of MySpondylitisTeam wrote about their son’s experience. “When the pain became intolerable and he couldn’t walk, I insisted on an MRI,” they said. “Then the diagnosis was AS, degeneration in the SI joint [sacroiliac joint, where the lower part of the spine connects with the pelvis], and spinal bone marrow edema.”

What Is Bone Marrow Edema?

The bone marrow is the soft, spongy tissue inside your bones that makes new blood cells. In healthy adults, it’s made of 50 percent fat and 50 percent water. However, people with inflammatory diseases, certain types of cancer, and infections may have more water than fat in their bone marrow. This condition is known as BME. The skewed ratio in BME puts pressure on the bones, leading to pain and swelling. Edema is the medical term for fluid buildup.

BME can be diagnosed with MRI scans. If you’re experiencing bone pain that gets worse while you’re sitting or lying down, talk with your doctor. They can perform an MRI to look for signs of BME.

How Are BME and AS Related?

People with AS often develop BME in the sacroiliac joint, which connects your lower spine and pelvis. Extra fluid from BME in the sacroiliac joint can contribute to your lower back pain and stiffness while living with AS. Inflammation of the sacroiliac joint is known as sacroiliitis. In the lumbar spine, when there’s active sacroiliitis, it leads to swelling and the buildup of fluid as seen with BME.

What Causes BME in AS?

The inflammatory response in AS leads to swelling and bones not forming correctly. The inflammatory response is the way your body reacts to harmful things like injuries, infections, or diseases. Your immune system sends special cells to the affected area to try to fix the problem. During spondylitis flares (periods of more intense symptoms and disease activity), the immune system releases chemicals such as tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-17 (IL-17).

These chemicals tell cells to break down bones. Bone erosion can lead to low bone mineral density and osteoporosis. It also creates inflammatory lesions (damage to bones), which further increases BME. This improper immune response can travel throughout the body, leading to symptoms like joint pain, gastrointestinal issues, and eye problems.

How Does AS Affect Your Bone Density?

BME has been associated with low bone mineral density — a measure of the amount of minerals in your bones. Because of the inflammation that affects the entire body and the increased chance of fractures due to limited movement, individuals with AS are more prone to developing osteoporosis. Bones with low mineral density can hold on to fluids, which can lead to BME.

How Does AS Affect Osteoporosis?

Osteoporosis develops in as many as 36 percent of people with AS because the inflammation caused by AS can lead to bone breakdown. When your bones lose density, they become more prone to breaks and fractures.

Diagnosing osteoporosis in people with AS can be challenging because AS may cause increased bone formation. This new bone formation can be harmful, as it can cause the spinal bones to fuse improperly. As a result, you might feel stiff, have trouble moving around, and find it hard to breathe. Because spinal fusion (new bone formation) and osteoporosis (breakdown of the bones) can occur at the same time, bone mineral density can be high in some parts of the body and low in other parts. Imaging techniques can help to diagnose these differences.

If you have osteoporosis, taking calcium and vitamin D supplements can help prevent bone erosion. Other ways to reduce your risk of osteoporosis include eating a healthy diet and exercising.

How Is Bone Marrow Edema Managed?

BME can get better on its own with rest and time. However, when BME is caused by an overactive immune system — such as with AS — you may need additional treatment.

Typical treatments include nonsteroidal anti-inflammatory drugs (NSAIDs), physical therapy, or steroid injections. NSAIDs are typically the first treatment choice for BME. NSAIDs help to control inflammation that may be caused by BME. It’s also important to stick to your AS treatment plan prescribed by your rheumatologist (specialist in autoimmune and musculoskeletal disorders such as AS).

NSAIDs

NSAIDs can help lessen swelling, stiffness, and pain. These medicines do this by stopping your body from making chemicals that cause inflammation. You can find over-the-counter NSAIDs like ibuprofen (Advil, Motrin) and naproxen (Aleve) in your local grocery store or pharmacy.

Disease-Modifying Antirheumatic Drugs

If NSAIDs aren’t effective in treating your BME, your rheumatologist may prescribe a disease-modifying antirheumatic drug (DMARD) to reduce inflammation and bone erosion. DMARDs are a group of drugs that adapt the immune system to lower inflammation and pain, reduce tissue damage, and slow down the advancement of AS. There are three types of DMARDs:

• Conventional synthetics — This type of medicine helps control inflammation and pain by changing how the immune system works. Examples include sulfasalazine and leflunomide, which are used when joints other than the spine are affected.
• Biologic therapy — Biologics are medicines made from living cells that help control inflammation. Common biologic medications for AS are TNF blockers and IL-17 inhibitors. Examples of TNF blockers include infliximab (Remicade), etanercept (Enbrel), and adalimumab (Humira). IL-17 inhibitors include secukinumab (Cosentyx) and ixekizumab (Taltz).
• Targeted synthetic therapy — These medications block specific factors causing inflammation. Janus kinase (JAK) inhibitors block chemical signaling that contributes to joint inflammation in AS. JAK inhibitors include tofacitinib (Xeljanz) and upadacitinib (Rinvoq).

Talk to Your Doctor About BME

If you have bone pain, talk to your doctor. They can run additional tests and perform an MRI to check for BME. The medications for BME might also be part of your treatment for AS. When taken correctly, DMARDs can improve your AS and BME symptoms.

Find Your Team

MySpondylitisTeam is the social network for people with spondylitis and their loved ones. On MySpondylitisTeam, more than 93,000 members come together to ask questions, give advice, and share their stories with others who understand life with spondylitis.

Are you experiencing bone pain with ankylosing spondylitis? Have you discussed bone marrow edema with your doctor? Share your experience in the comments below, or start a conversation by posting on your Activities page.