There are 5 metacarpal bones in the hand which join the wrist bones to the fingers and thumb.
These bones are susceptible to fractures in combat sports. These can occur from loading the bone from a force across the knuckle or a direct blow to the side of the bone. The bone most commonly involved is the 5th metacarpal (the bone at the base of the little finger). This fracture most commonly occurs from improper alignment of the hand when punching through the 4th and 5th metacarpals rather than the 2nd and 3rd metacarpals. These abnormal forces to the bones can also occur when the hand is not in line with the forearm such as during a hook or upper cut punch. The side of the metacarpal bone maybe fractured with a direct blow during a knife hand strike. Fractures of the thumb or 1st metacarpal occurs more commonly when the thumb is pulled away from the hand and bent outward or jammed from the end of the thumb when punching or from a direct side blow such as during a ridgehand strike.
Types of Metacarpal Fractures
Fractures can occur anywhere along the bone. The most common occurs along the neck of the metacarpal bone at its weakest point. This is called a “Boxer’s” fracture.
The next most common break occurs in the middle portion or shaft of the bone.
The fracture can extend into the joint and usally occurs back towards the wrist: common at the base of the thumb (Bennett’s fracture) or at the base of the 5th metacarpal.
Symtoms of Metacarpal fractures
- Deformity with a prominence at the top of hand or loss of knuckle appearance
- Rotational abnormality with overlapping of the involved digit under the adjacent digit
Treatment of Metacarpal fractures
Most fractures will heal in the position they are but in many cases there is displacement or angulation across the break and, if left uncorrected, can lead to permanent weakness in the hand. Fractures take 4-6 weeks to heal. Boxer’s fractures of the 5th metacarpal are usaully treated with a splint accepting angulation up to 70 degrees. There is usally no funcational abnormality accepting a loss of knuckle prominence. Surgical repair of these fractures is usually avoided since the placement of pins so close to the knuckle joint would most likley lead to joint stiffness and loss of function. Fractures of the shaft usually are angulated and crooked and need alignment restored with surgical placement of stainless steel or titanium pins, screws and/or plates. Fractures at the base of the metacarpal frequently extend into the joint and must be repaired surgically as perfectly as possible to prevent traumatic arthritis from developing.
Recovery after Metacarpal fractures
A splint or cast is applied during the 4-6 week healing period. After healing of the fracture, therapy is usually necessary to relieve stiffness and restore strength to the hand.The overall recovery before return to combat striking is approximately 3 months from the time of injury depending on the type of fracture and whether surgery was required.
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