Chronic Recurrent Multifocal Osteomyelitis (CRMO)


Chronic recurrent multifocal osteomyelitis (CRMO), or chronic nonbacterial osteomyelitis (CNO), is an autoinflammatory disorder that causes bone pain due to inflammation in the bones not caused by infection. Chronic recurrent multifocal osteomyelitis (CRMO) can take months to years to diagnose. CRMO was previously thought to be rare, occurring in about 0.4 out of 100,000 people per year. As recognition of CRMO is increasing, it appears to be more common than that. In fact, CRMO may be nearly as common as bone infections. The average age that CRMO starts is 9 to 10 years. More girls are affected than boys.

What Are the Signs/Symptoms?

Tenderness in the affected area results in complaints of bone pain. The pain can cause the person to avoid using the affected body part. Some people with CRMO can develop arthritis (joint swelling). Fatigue is also a common symptom. A small fraction of people with CRMO has a genetic component. Some families have more than one person with CRMO. Diagnosis is based on exams, imaging (such as x-rays, bone scan or MRI), bone biopsy, and laboratory (blood) tests. CRMO is monitored by the following symptoms and imaging studies. MRI is the best way to assess resolution of active bone lesions and/or detect new lesions.

What Are Common Treatments?

Treatment of CRMO depends on how severe it is and which bones it affects. Treatment usually starts with non-steroidal anti-inflammatory drugs (NSAID), but some patients need additional medications, including methotrexate, biologics (such as etanercept, adalimumab, infliximab, anakinra) and bisphosphonates (pamidronate, zoledronic acid). People taking methotrexate and biologic medications are at a higher risk of infection and should be evaluated by their rheumatology provider if they develop fever or symptoms of infection. Tuberculosis (TB) screening is required prior to starting biologic medications.

Living with CRMO

For people with CRMO, life often involves taking medications and having follow-up visits with a rheumatology provider. Depending on which bones are affected, some people need to limit activities to prevent serious injury or bone damage. People with spine involvement are at risk for serious injury if spine fracture occurs. People with CRMO should discuss activity restrictions with their healthcare provider. In some people, it is possible for CRMO to resolve either for a short period of time or permanently. For others, even though CRMO is controlled, chronic pain (amplified musculoskeletal pain) that does not respond to medications can develop. This type of pain may require additional treatment and physical therapy.

Updated February 2023 by Mohammad Ursani, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.

We use cookies on our website to improve our service to you and for security purposes. By continuing to use our site without changing your browser cookie settings, you agree to our cookie policy and the use of cookies. See ACR Policies