Boutonnière Deformity

To be categorized as a Boutonnière deformity, a finger must experience both of the following problems:

  1. A bent position of the middle joint of a finger or the first joint of the thumb
  2. A bent back position of the end joint of a finger or thumb
Boutonniere deformity of a finger
Figure 1: A Boutonnière deformity

Causes

A Boutonnière deformity can happen for several reasons. It can happen from a cut of the tendon on the back of the finger or the thumb. It can also be due to tearing or weakening of the same tendon due to an injury or from a disease like rheumatoid arthritis. This results in the bent position of the joint.

This bent position causes the small tendons on the side of the finger to slide toward the palm side. This worsens the bent position of the finger's middle joint. There can then be more pull on the end joint of the finger. This causes the small joint to bend further back.

Signs and Symptoms

A cut of the tendon on the back of the middle joint will result in difficulty straightening that joint. The change in position of the end joint may not be seen initially but usually happens over time.

The deformity may become worse over time if not treated. If the deformed position is not treated, it can result in stiffness. This can become permanent if you do not seek treatment.

Anatomy drawing of a boutonniere deformity
Figure 2: The anatomy of a Boutonnière deformity

Treatment

There are many treatments for a Boutonnière deformity. Splinting can be used, particularly if it is started soon after the tendon is injured. Splinting alone may not give a good result in a case where the deformity is caused by rheumatoid arthritis.

Multiple different surgical options have been used to treat this problem. In the case of a cut tendon, the best results are generally seen when the tendon is repaired early. Even with surgery, a normal position of the joints is commonly not seen.

Next step: Your treatment plan will vary, depending on your situation. Visit a hand surgeon to determine the best option for you.

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Source: American Society for Surgery of the Hand / HandCare.org patient education PDF, converted into a responsive webpage format.