Boutonnière deformity is the result of an injury to the tendons that straightens the middle joint of your finger. The result is that the middle joint of the injured finger will not straighten, while the fingertip bends back. Unless this injury is treated promptly, the deformity may progress, resulting in permanent deformity and impaired functioning.
Boutonnière deformity is generally caused by a forceful blow to the top (dorsal) side of a bent (flexed) middle joint of a finger.
It also can be caused by a cut on the top of the finger, which can sever the central slip (tendon) from its attachment to the bone. The tear looks like a buttonhole (“boutonnière” in French). In some cases, the bone actually can pop through the opening.
Boutonnière deformities may also be caused by arthritis.
Signs of boutonnière deformity can develop immediately following an injury to the finger or may develop a week to 3 weeks later.
Nonsurgical treatment is usually preferred, and may include:
Splints: A splint will be applied to the finger at the middle joint to straighten it. This keeps the ends of the tendon from separating as it heals. It also allows the end joint of the finger to bend. It is important to wear the splint continuously for the recommended length of time — usually 6 weeks for a young patient and 3 weeks for an elderly patient. Following this period of immobilization, you may still have to wear the splint at night.
Exercises: Your physician may recommend stretching exercises to improve the strength and flexibility in the fingers.
Protection: If you participate in sports, you may have to wear protective splinting or taping for several weeks after the splint is removed.
People with boutonnière deformity caused by arthritis may be treated with oral medications or corticosteroid injections, as well as splinting.
While nonsurgical treatment of boutonnière deformity is preferred, surgery is an option in certain cases, such as when:
The deformity results from rheumatoid arthritis.
The tendon is severed.
A large bone fragment is displaced from its normal position.
The condition does not improve with splinting.
Surgery can reduce pain and improve functioning, but it may not be able to fully correct the condition and make the finger look normal. If the boutonniere deformity remains untreated for more than 3 weeks, it becomes much more difficult to treat.