Arthritis mutilans is a rare form of inflammatory arthritis that causes severe inflammation. This leads to the wearing down of joints and bone tissues in the hands and feet.

This article will look at the causes of arthritis mutilans (AM), its symptoms, how it is diagnosed, and what treatment options are available.

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Arthritis is an autoimmune disease that causes inflammation, particularly in the joints.

Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are two conditions that can progress to AM.

RA is a long-term, progressive autoimmune disease that causes inflammation throughout the body, especially in the joints.

Also an autoimmune disease, PsA causes joint pain, swelling, and inflammation to the skin. If not controlled, both conditions can lead to joint damage.

As a severe form of RA or PsA, AM destroys bone and cartilage of joints and causes bone resorption. Bone resorption is part of the bone modeling process involving the breakdown and absorption of old bone tissue.

In people with AM, bone tissue rebuilding does not take place. Instead, the soft tissues of the bones collapse.

Arthritis mutilans in PsA and RA

AM is uncommon, affecting about 5 percent of people with PsA and 4.4 percent of people with RA. It mainly affects the smaller joints.

Arthritis mutilans is one of the most severe forms of PsA. It is marked by clear and severe damage to the bone tissue in the joints.

One study found that people with PsA who eventually develop severe joint damage and deformity have higher disease activity when symptoms begin.

In 2003, The New England Journal of Medicine reported on a 94 year old woman who had RA since childhood. When she first sought treatment in her 60s, she presented with AM and severe joint deformity. Imaging showed severe bone resorption in her hands and wrists and collapse of the bone tissue.

This created a condition called “telescoping fingers.” Telescoping fingers occurs when the bones dissolve and soft tissues cannot hold the fingers up and they end up pulling together in a heap-like fashion.

In RA, severe AM deformities are most visible in the hands and wrists. They tend to occur when RA is not properly treated.

Rare cases

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Severe deformities can occur when RA is not treated. These are seen most often in the hands and wrists.

Cases of AM have also been reported in people with the following conditions:

  • systemic lupus erythematosus (SLE)
  • mixed tissue connective disease (MTCD)
  • juvenile idiopathic arthritis (JIA)
  • multicentric reticulohistiocytosis (MRH)

Unfortunately, the research on these types of AM and their prevalence is lacking and often outdated.

In 2008, a rare case of a 45-year old woman with SLE and AM deformities was reported. The woman had destructive changes in both her hands and required multiple surgeries to repair the damage.

A 1978 study in the Annals of the Rheumatic Diseases, reported that one of the 20 people with MTCD had AM. In addition to joint deformities, the person had significant problems with movement.

An article in the journal Internal Medicine reported on a 60 year old woman who was diagnosed with JIA as a teenager. She had a “pencil-in-cup deformity” in her hand and deformed, shortened fingers. A pencil-in-cup deformity is when the tip of a bone becomes pointed like a sharpened pencil. The nearby surface becomes rounded due to wearing away.

MRH is a very rare and destructive type of arthritis with only about 250 reported cases worldwide. MRH can be identified by wearing away in multiple joints, and by lesions on the skin, mucous membranes, and internal organs.

MRH progresses to AM in 45 percent of cases and it affects more women than men. It is resistant to disease modifying drugs (DMARDS) and steroid medications.

The main symptom of AM is severe bone tissue destruction. This leads to permanent joint deformity and an inability to move the joint. Because AM is a progressive disease, it will eventually get worse. It worsens quickly in some people and in a stop-start manner in others.

Deformities caused by AM are often clearly visible in a person’s hands, fingers, feet, and toes. The condition may eventually result in telescoping fingers and toes seen on X-rays. Sometimes the bones do not reabsorb, and the joints fuse together or get worn away. When this happens, the function of the joint is completely lost. This type of fusion is called ankylosis, or an abnormal stiffening of the joints.

In the worst cases, a condition called glass opera hand occurs, where the fingers are pulled out of shape due to severe destruction and bone absorption. The glass opera hand deformities are often seen in advanced cases of RA.

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AM may be treated with intensive physical therapy and medications such as nonsteroidal anti-inflammatory drugs.

Early and aggressive physical therapy, especially in the hands, can help to delay or prevent AM from destroying the joint and stopping the joint from working.

AM can also be treated with medications, including DMARDs, nonsteroidal anti-inflammatory drugs (NSAIDs), and corticosteroids.

Some evidence suggests that AM can be successfully treated with medications called TNF inhibitors. One 2009 follow-up study found AM associated with PsA responded well to TNF inhibitors. The patients experienced joint and skin improvements, although previous deformities could not be treated.

Other medications that have been shown to work on psoriatic arthritis are anti-IL-17 agents, anti-IL-12 and 23 agents, and PDE4 inhibitors. The medications that work on RA are different, so it is thought that the two diseases probably are not caused in the exact same way.

Splinting can reduce inflammation and stabilize joints, but too much splinting can result in weakened muscle tissue.

There has been some research to indicate AM can be repaired with different types of surgery. These included:

  • iliac bone graft procedures: surgical process of repairing damaged bones and joints
  • arthrodesis: surgical fix involving joint fusion of the fingers and toes

A report in the March 2008 issue of Hand outlined research that included surgery on a person with SLE. Both of these surgical techniques were reported in the medical textbook, Plastic and Reconstructive Surgery: Approaches and Techniques as successful and effective treatments for AM.

Arthritis mutilans is a rare form of advanced joint disease. Once a person has been diagnosed with AM, it is not known how the condition will progress.

Treatments will work to slow down the progression of the disease and joint damage and help to improve quality of life. While there is potential for complications, deformity, and loss of movement, research does show that there are people living well into old age with AM.

Diagnosis of AM is best made by looking for evidence of joint deformities in X-rays and MRIs. Doctors will also rely on physical examination of visible joint destruction and blood work to measure disease activity from the underlying condition.