Chronic Nonbacterial Osteomyelitis (CNO)/Chronic Recurrent Multifocal Osteomyelitis (CRMO)

How to pronounce it:

Osteomyelitis - os-tee-oh-mEYE-uh-lai-tis


AiArthritis defines CNO/CRMO as:


Chronic Nonbacterial Osteomyelitis (CNO)/Chronic Recurrent Multifocal Osteomyelitis (CRMO) is an autoinflammatory disease where the bones become inflamed without any bacterial infection. They cause persistent bone pain and swelling, primarily in areas like long bones, pelvis, shoulder, and spine. Cytokines like IL-1β and IL-10 play a role in the disease. This disease is mostly found in children.

Symptoms

Symptoms of AiArthritis Diseases Regardless of Diagnosis

Common in All AiArthritis Diseases



  • Periods of worsening symptoms are called flares. A flare can last for hours, days, weeks, or months.
  • Condition improves with activity and exercise and worsens with rest.
  • When inflammation is left uncontrolled due to lack of proper treatment, comorbidities can develop. 70% of patients with chronic, lifelong disease will develop comorbidities, including dual or triple diagnoses.

 “Auto” Symptoms






  • Severe fatigue or exhaustion that may not be helped by caffeine/stimulants and can happen even after a long period of rest.
  • “Brain fog” - or periods of time where thinking gets clouded and it becomes difficult to concentrate.
  • Flu-like symptoms, without having the flu- nausea, muscle weakness, and general malaise.
  • Fever, typically low grade in autoimmune and higher grade in autoinflammatory (% strongly varies per disease).


Reference: Early Symptoms of AiArthritis Study, AiArthritis, 2019.


View Early Symptoms Study

Inflammatory Arthritis Symptoms


  • Severe stiffness in one or more joints, especially in the morning or after sitting for long periods of time. 
  • Episodes of joint pain that may last for hours, days, or even weeks, that can appear and disappear suddenly. Often described as “jumping pain” into different locations.


Typically the joint pain will coincide with one or more “Auto” symptoms and start and stop suddenly - for no apparent reason (which is called a "flare").  Some people will experience all of the above symptoms, others only a few.  If you have any of the arthritis features, and at least one of the “Auto” features, please consult your physician about a referral to a rheumatologist.


Symptoms Often Associated with CNO/CRMO:

  • Bone pain particularly in the long bones, knee, ankle, wrist, back, pelvis or collarbone
  • Exudate (fluid that leaks out of blood vessels into nearby tissues)
  • Synovial thickening
  • Damage to articular cartillage
  • Swelling and warmth on skin where bones are painful
  • May be associated with inflammatory skin disorders such as psoriasis vulgaris, palmoplantar pustulosis, acne, pyoderma gangrenosum and rarely
  • May be associated with Sweet's syndrome, and/or Crohn's disease, or ulcerative colitis


What fellow patients want you to know

Do you have CNO/CRMO? Let us know what YOU would want those others or those who are not yet diagnosed to know!

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More About CNO/CRMO

Diagnosing CNO/CRMO

There’s no single definitive test that can confirm a CNO/CRMO diagnosis, so rheumatologists look at a combination of physical exam, blood tests (ESR and CRP), imaging (x-ray, MRI, CT, nuclear bone scan), and bone biopsy along with a family history of autoimmune or autoinflammatory disease. CNO/CRMO diagnosis also includes the exclusion of other possible diseases because the symptoms overlap with several others.

Interesting Facts about this Disease

  • 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.
  • The average age that CRMO starts is 9 to 10 years. More girls are affected than boys.

Other Resources

In an effort to ensure this page has the most accurate and up-to-date information, this page is currently awaiting medical review. Some information is subject to change.


Page Last Updated: 9/1/2023

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