What is CRMO?
Chronic Recurrent Multifocal Osteomyelitis (CRMO) is a rare inflammatory disease that affects the bones.
It is not caused by infection.
Doctors may also use the name Chronic Non-bacterial Osteomyelitis (CNO).
- Chronic means the condition lasts more than 3 months.
- Recurrent means symptoms come and go over time.
- Multifocal means more than one part of the body is affected.
- Osteomyelitis means inflammation inside the bone.
Sometimes the term CNO is used when only one bone area is affected, and CRMO when several areas are affected.
Who can get CRMO?
CRMO most often begins in children aged 7 to 10 years.
It affects about twice as many girls as boys.
However, adults can also have CRMO.
Because CRMO is rare and symptoms can look like other illnesses, many people wait a long time for a correct diagnosis.
The most common symptom is bone pain.
Bone pain from CRMO often:
- feels deep or sharp
- lasts longer than muscle pain
- may not improve with movement or rest
Pain can occur in many bones. Common areas include:
- knees
- ankles
- spine (back bones)
- jaw
- collarbone
- pelvis
Symptoms often flare up for several days, then improve.
Other symptoms
Some people may also have:
- swelling around painful bones or joints
- fever
- nausea
- fatigue (extreme tiredness)
- heavy sweating or night sweats
Skin and other conditions
Some people with CRMO also develop:
- severe acne
- skin blisters
- psoriasis
- inflammatory bowel disease (IBD)
CRMO happens when the body’s inflammation system becomes overactive.
Inflammation is the body’s normal response to injury or illness. In CRMO, the body triggers inflammation even when there is no infection.
In some people, CRMO is linked to changes(variants) in certain genes that control inflammation.
Two examples are genes related to the interleukin-1 (IL-1) pathway, which helps regulate inflammation.
When these genes do not work normally, the inflammation signal can stay switched on, causing repeated bone inflammation.
Not everyone with CRMO has a known genetic change. Doctors can still diagnose CRMO based on symptoms and medical tests.
Research into the causes of CRMO is ongoing.
Is CRMO autoimmune or autoinflammatory?
CRMO is an autoinflammatory disease.
This means the innate immune system (the body’s early defence system) becomes overactive.
This is different from autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues.
There is no single test that confirms CRMO.
Doctors usually diagnose it by:
- Reviewing symptoms
- Examining the patient
- Ruling out other conditions
This process can take time.
Tests may include:
- blood tests
- X-rays
- MRI scans
- CT scans
- bone scans
- sometimes a bone biopsy
Doctors must rule out conditions that can look similar, such as:
- bone infections
- bone cancer
- other inflammatory diseases
International guidelines from the European Alliance of Associations for Rheumatology and the American College of Rheumatology provide criteria doctors can use to help diagnose children with CNO/CRMO.
There is no cure for CRMO, but treatments can help reduce pain and inflammation.
Common treatments include:
Anti-inflammatory medicines
Doctors often prescribe non-steroidal anti-inflammatory drugs (NSAIDs) such as:
- Ibuprofen
- Naproxen
These help reduce pain and swelling.
Corticosteroids
Short courses of steroids may be used during severe flare-ups.
Bone medicines (bisphosphonates)
Medicines such as:
- Pamidronate
- Zoledronic acid
may be used to help control bone inflammation.
Biologic medicines
If other treatments do not work, doctors may prescribe biologic medicines that block inflammatory signals.
These target parts of the immune system that cause inflammation.
CRMO can be painful and difficult to live with, but symptoms often come and go.
Many people experience:
- flare-ups (when symptoms get worse)
- remission (when symptoms improve or disappear)
These ups and downs can affect:
- school or work
- sports and physical activity
- social life
- mental wellbeing
People with CRMO often see several specialists, including:
- rheumatologists
- orthopaedic doctors
- immunologists
- dermatologists
- a general practitioner (GP), who coordinates care
Support from family, friends, teachers and employers can make a big difference.
Helpful resources:
These organisations provide information and support for people with CRMO and their families.
IMPORTANT NOTE:
Currently, not all medications commonly used to treat SAIDs are available in Australia and New Zealand, and those available may be difficult to access.
ANZFAID is committed to continuing to advocate for improved options, and timely and affordable access to treatment.