A Patient's Guide to Mallet Finger Injuries
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Introduction
When you think about how much we use our hands, it's not
hard to understand why injuries to the fingers are common.
Most of these injuries heal without significant problems.
One such injury is an injury to the distal interphalangeal,
or DIP, joint of the finger. This joint is commonly injured
during sporting activities such as baseball. If the tip of
the finger is struck with the ball, the tendon that attaches
to the small bone underneath can be injured. Untreated, this
can cause the end of the finger to fail to straighten completely.
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This guide will help you understand
• what parts make up the DIP finger joint
• what types of injuries affect this joint
• how the injury is treated
• what to expect from treatment
Anatomy
What parts of the finger are involved?
 The
finger joints work like hinges when the fingers bend and straighten.
The main knuckle joint is the metacarpophalangeal joint (MCP).
It is formed by the connection of the metacarpal bone in the palm
of the hand with the first finger bone, or proximal phalanx.
Each finger has three phalanges, or small bones, separated by two
interphalangeal (IP) joints. The one closest to the MCP (knuckle)
is called the PIP, or proximal IP joint. The joint near the
end of the finger is called the DIP, or distal IP joint.
The extensor tendon is attached to the base of the distal phalanx.
When it tightens, the finger straightens. Another tendon, the flexor
tendon, is attached to the palm of the finger. When it pulls, the
DIP bends.
View graphic of tendon anatomy
of DIP.
Causes
How do these injuries of the DIP joint occur?
A mallet finger results when the extensor tendon is torn from the
attachment on the bone. When this occurs, a small fragment of bone
may be pulled, or avulsed, from the distal phalanx. The result is
the same in both cases--the end of the finger droops down and cannot
be straightened.
Symptoms
What do mallet finger injuries look and feel like?
Initially, the finger is painful and swollen around the DIP joint.
The end of the finger is bent and cannot be straightened voluntarily.
The finger can be straightened easily with help from the other hand.
Diagnosis
What tests will my doctor do?
Usually the diagnosis is evident from the physical examination.
X-rays are required to see if there is an associated avulsion fracture
since this may change the recommended treatment. No other tests
are normally required.
View graphic of mallet finger.
Treatment
What can be done for the problem?
Nonsurgical Treatment
Treatment for mallet finger is usually nonsurgical. If there is
no fracture, then the assumption is that the end of the tendon has
been ruptured, allowing the end of the finger to droop. Usually
continuous splinting for six weeks followed by six weeks of nighttime
splinting will result in satisfactory healing and allow the finger
to extend.
The key is continuous splinting for the first six weeks. The splint
holds the DIP joint in full extension and allows the ends of the
tendon to move as close together as possible. As healing occurs,
scar formation repairs the tendon. If the splint is removed and
the finger is allowed to bend, the process is disrupted and must
start all over again. The splint must remain on at all times--even
in the shower.
View graphic of stack splint.
While a simple homemade splint will work, there are many splints
that have been designed to make it easier to wear at all times.
In some extreme cases where the patient has to use the hands to
continue working (such as a surgeon), a metal pin can be placed
inside the bone across the DIP joint to act as an internal splint
and allow the patient to continue to use the hand. The pin is removed
at six weeks.
View photo of stack splint.
Splinting will even work when the injury is quite old. Most doctors
will try a six week trial of splinting to see if the drooping lessens
to a tolerable limit before considering surgery.
 Surgery
Surgical treatment is reserved for unique cases. The first is when
the result of conservative treatment isintolerable. If the finger
droops too much, the tip of the finger gets caught as you try to
put your hand in a pocket. This can be quite a nuisance. If this
occurs, the tendon can be repaired surgically, or the joint can
be fused in a fixed position.
The other case is when there is a fracture associated with the
mallet finger. If the fracture involves enough of the joint, it
may need to be repaired. This may require pinning the fracture.
If the damage is too severe, it may require fusing the joint in
a fixed position.
View graphic of reattachment
with pins.
Rehabilitation
What will my recovery be like?
Rehabilitation during and following treatment for a mallet finger
focuses mainly on keeping the other joints mobile and preventing
stiffness from disuse. A physical or occupational therapist may
be consulted to teach you home exercises and make sure the other
joints do not become stiff. Once the mallet finger has healed sufficiently,
exercises may be instituted to strengthen the finger involved and
increase flexibility.
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