Mallet finger is a deformity in which the fingertip is curled in and cannot straighten itself.
This deformity usually results from injury, which either damages the tendon or tears the tendon from the bone. It can affect one or more fingers. A doctor can make the diagnosis by examining the finger. An x-ray is usually taken to be sure that there is no fracture. The usual treatment is placing a splint on the finger with the finger straightened. The tendon may take 6 to 10 weeks to heal. Mallet finger rarely requires surgery, unless a large fragment of bone has broken off or the joint is partially dislocated.
Swan-neck deformity is a bending in (flexion) of the base of the finger, a straightening out (extension) of the middle joint, and a bending in (flexion) of the outermost joint.
The most common cause is rheumatoid arthritis. Other causes include untreated mallet finger, looseness (laxity) of the fibrous plate inside the hand at the base of the fingers or of the finger ligaments, muscle spasm affecting the hands, and misalignment in the healing of a fracture of the middle bone of the finger. Normal bending of the finger may become impossible. The deformity can therefore result in considerable disability.
True swan-neck deformity does not affect the thumb, which has one less joint than the other fingers. However, in a variant of swan-neck deformity, called duck-bill deformity, the top joint of the thumb is severely overstraightened with a bending in of the joint at the base of the thumb to form a 90° angle. If duck-bill deformity and swan-neck deformity of one or more fingers occur together, the ability to pinch can be seriously reduced.
A doctor makes the diagnosis by examining the hand and finger.
Treatment is aimed at correcting the underlying disorder when possible. Mild deformities may be treated with finger splints (ring splints), which correct the deformity while still allowing a person to use the hand. Problems with the ability to pinch can be greatly improved by surgically realigning the joints or by fusing the thumb or finger joints together (called interphalangeal arthrodesis) into positions that allow for optimal function.
Boutonnière deformity (buttonhole deformity) is a deformity in which the middle finger joint is bent in a fixed position inward (toward the palm) and the outermost finger joint is bent excessively outward (away from the palm).
This disorder most often results from rheumatoid arthritis (see Joint Disorders: Rheumatoid Arthritis (RA)) but can also occur from injury (such as deep cuts, joint dislocation, or fractures) or osteoarthritis (see Joint Disorders: Osteoarthritis (OA)). People with rheumatoid arthritis can develop the disorder because they have long-standing inflammation of the middle joint of a finger. If the deformity is caused by an injury, the injury usually occurs at the base of a tendon (called the middle phalanx extensor tendon). As a result, the middle joint (called the proximal interphalangeal joint) becomes “buttonholed” between the outer bands of the tendon that runs to the end of the finger. The deformity can, but need not, interfere with hand function. The doctor makes the diagnosis by examining the finger.
A boutonnière deformity caused by an extensor tendon injury can usually be corrected with a splint that keeps the middle joint fully extended for 6 weeks. When splinting is ineffective, or when boutonnière deformity is due to rheumatoid arthritis, surgery may be needed.
Dupuytren’s contracture (palmar fibromatosis) is a progressive tightening of the bands of fibrous tissue (called fascia) inside the palms, causing a curling in of the fingers that eventually can result in a clawlike hand.
Dupuytren’s contracture develops in people who are genetically predisposed.
Treatment involves injection of a corticosteroid into a tender nodule or, if the hand is already scarred, surgery to correct contracted (clawed) fingers.
Dupuytren’s contracture is a common hereditary disorder that occurs particularly in men, especially after age 45. However, having the abnormal gene does not guarantee that someone will have the disorder. About 5% of people in the United States have Dupuytren’s contracture. The disorder affects both hands in 50% of people. When only one hand is affected, the right hand is involved twice as often as the left.
Dupuytren’s contracture is more common among people with diabetes, alcoholism, or epilepsy. The disorder is occasionally associated with other disorders, including thickening of fibrous tissue above the knuckles (Garrod’s pads), shrinking of fascia inside the penis that leads to deviated and painful erections (penile fibromatosis [Peyronie’s disease]—see Penile and Testicular Disorders: Peyronie’s Disease), and nodules on the soles of the feet (plantar fibromatosis). However, the precise mechanism that causes the fascia of the palm to thicken and curl in is unknown.
The first symptom is usually a tender nodule in the palm (most often at the third or fourth finger). The nodule may initially cause discomfort but gradually becomes painless. Gradually, the fingers begin to curl. Eventually, the curling worsens, and the hand can become arched (clawlike). The doctor makes the diagnosis by examining the hand.