What Is Chronic Recurrent Multifocal Osteomyelitis?

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare bone disorder that causes chronic inflammation of the bones. While CRMO is treatable, it may slow down childhood bone growth and lead to permanent bone deformities in both adults and children.

There is conflicting evidence about the true prevalence of CRMO because little is known about it, and researchers believe a great number of people with the condition are likely undiagnosed.

What researchers do know is that CRMO affects both adults and children, although symptoms often begin in childhood. The average age of diagnosis is around 9 to 10 years of age.

CRMO Symptoms

Chronic recurrent multifocal osteomyelitis will initially present with bone pain and bone lesions (areas of bone that have changed or become damaged). It can affect any bone in the body. Some people can have many affected areas, while others only a few affected bones.

CRMO commonly affects the long bones of the body. These are the bones that are longer than they are wide. They are hard and dense and provide strength, structure, and mobility. The femur, tibia, and fibula in the lower limbs and the humerus bone, the ulna bone, and the radius bone of the upper limbs are all long bones.

Symptoms of CRMO in children include:

• Deep aching pain
• Limping
• Tenderness of affected areas
• Spine, ankle, and foot problems

Additional symptoms caused by CRMO affecting both adults and children include:

• Periodic fevers
• Skin diseases such as acne, palmoplantar pustulosis (a skin condition that causes blisters and fluid-filled bumps on the hands and feet), and psoriasis (an inflammatory skin condition)
• Eye inflammation—usually a condition called uveitis that affects the middle of the eye
• Digestive symptoms including abdominal pain and diarrhea­­—some people with CRMO may develop, inflammatory bowel disease, a condition that causes chronic, ongoing inflammation of the digestive tract
• Joint pain and swelling
• Chronic fatigue

Left untreated, chronic recurrent multifocal osteomyelitis can cause bony lumps to grow on the bones of the spine or joints, bone deformity, and disability. CRMO may also affect bone growth in children, resulting in leg length discrepancy from bone lesions on growth plates.

Causes

CRMO is considered an autoinflammatory disorder—and not an autoimmune disease. Autoinflammatory diseases are caused by gene mutations in molecules involved in regulating immune system responses. With CRMO, the immune system attacks the bones causing inflammation, although there is no infection.

Specific causes for CRMO are unknown, but researchers believe genetic factors might play a role. In fact, there is a significant genetic contribution in CRMO disease risk, according to a 2017 Pediatric Rheumatology report. Additionally, there are many instances where more than one family member is afflicted with CRMO.

Diagnosis

Your healthcare provider will use a variety of tests to help make a diagnosis, but there are no unique or specific tests that can confirm a diagnosis of CRMO.

Lab testing is usually normal with CRMO but may show anemia (a lack of healthy red blood cells to carry adequate oxygen to your body's tissues) and elevated markers of inflammation.

Damaged or altered bone can be seen on X-rays, bone scans, and magnetic resonance imaging (MRI) scans. A bone biopsy may show acute (short-term) or chronic inflammation. 

For diagnosing and treating this condition, it is best to work with someone who is familiar with inflammatory bone diseases, such as a rheumatologist. Ask your healthcare provider for a referral.

CRMO should not be confused with osteomyelitis, which is an infection of the bone. While it can be serious, osteomyelitis is caused by a specific bacterium called Staphylococcus aureus. It often results after an injury or surgical procedure that exposes the bone to infection. Fortunately, osteomyelitis can be successfully treated with antibiotics.

Treatment

There is no cure for CRMO, but the condition is treatable. The goals of treatment for both adults and children are to reduce pain, manage mobility, prevent bone lesions and bone deformities, and to improve quality of life.

The first-line treatment for chronic recurrent multifocal osteomyelitis is nonsteroidal anti-inflammatory drugs (NSAIDs). Common NSAIDs used for CRMO are naproxen, meloxicam, and indomethacin.

If NSAIDs aren’t helpful, antirheumatic drugs like corticosteroids, methotrexate, and or sulfasalazine are next-line therapy. These medications are available in pill form and methotrexate can be given as either a pill or an injection.

If symptoms continue or you have a co-occurring immune-related disease, your healthcare provider may suggest biologic drugs called TNF inhibitors. TNF inhibitors like etanercept, adalimumab, and infliximab are given either by injection or intravenously through a vein.

Bisphosphonates, including pamidronate and zoledronic acid, can also treat CRMO and reduce the risk for bony growth and deformities. These medicines are given intravenously. Research shows bisphosphonates may lead to remission in 73% of people with CRMO after NSAID and corticosteroid failure.

Bisphosphonates may also be considered if the vertebrae is involved.

While medications can help, they are not the only treatments used for managing chronic recurrent multifocal osteomyelitis. For example, a physiotherapist can work both adults and children to teach them exercises to help keep their muscles strong and their joints moving.

An occupational therapist can suggest changes to make everyday tasks easier at home, at school, or on the job. A mental health therapist can help with managing the emotional changes of a chronic illness.

A Word From Verywell

The outlook for chronic recurrent multifocal osteomyelitis varies from person to person based on disease activity (symptoms) and treatment responses. For most people with CRMO, they will be taking medications and having follow-up visits with their healthcare providers for the rest of their lives.

Work with your healthcare provider or your child’s practitioner to keep CRMO controlled and follow-up when chronic pain seems worse or if medications aren’t helping. These are the best ways to feel better and to continue with everyday activities.