Metacarpal Fracture

A metacarpal fracture or broken metacarpal is a fracture (break) of the tubular bones within the palm (metacarpals). They classically occur in the small finger metacarpal bone in boxers or athletes of other sports or activities. This type of fracture has therefore become to be known as a “boxer’s fracture.” Each of the digits of the hand has a corresponding metacarpal bone associated with it, and any of these metacarpals may be fractured during a high energy impact to an athlete’s hand.

These injuries are also common in other sports besides boxing. For example Ronnie Brown of the Miami Dolphins and Tony Romo of the Dallas Cowboys each spent time on the IR from suffering a metacarpal fracture as did the Mavericks Jason Terry who had surgery to fix his metacarpal fracture.

Anatomy of metacarpal

The metacarpals are the tubular bones that comprise most of the space in the palm. Each of the fingers (digits) has a corresponding metacarpal that links the wrist bones to the phalanges (individual bones of the fingers). There are flexor tendons on the palm side of the metacarpals that act to flex, or bend the fingers as in making a fist. There are extensor tendons on the back of the hand that act to extend or straighten the fingers. In between the metacarpal bones are the small intrinsic muscles (the interosseous and lumbrical muscles) that further help to control fine finger motion. When a metacarpal fracture happens, the finger flexors and the intrinsic muscles act together to bend the fracture toward the palm (apex dorsal angulation). How much the fracture bends is somewhat dependant on how much force caused the injury in the first place. A higher force injury can lead to more bending (displacement of the fracture).

In an athlete’s normal uninjured hand, there is less motion at the joints of the index and long finger and more motion at the ring and small fingers. The increased motion at the two smaller fingers allows for more angulation to be acceptable as the fracture heals. This is because the increased normal motion of these two metacarpal bones can allow the hand to adapt to any permanent deformity. On the other hand, the index and long fingers’ have lesser ability to adapt to metacarpal fracture bending because they have less natural motion. The normal motion of the metacarpals can be seen when one makes a tight fist while watching the ring and small finger side of the back of the hand bend further inward.