Bennett's fracture
| Bennett fracture | |
|---|---|
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| Bennett fracture on x-ray | |
| Classification and external resources | |
| Specialty | emergency medicine |
| ICD-10 | S62.2 |
| ICD-9-CM | 815.x1 |
| eMedicine | orthoped/19 |
Bennett fracture is a fracture of the base of the first metacarpal bone which extends into the carpometacarpal (CMC) joint. This intra-articular fracture is the most common type of fracture of the thumb, and is nearly always accompanied by some degree of subluxation or frank dislocation of the carpometacarpal joint.
Symptoms of Bennett fracture are instability of the CMC joint of the thumb, accompanied by pain and weakness of the pinch grasp. Characteristic signs include pain, swelling, and ecchymosis around the base of the thumb and thenar eminence, and especially over the CMC joint of the thumb. Physical examination demonstrates instability of the CMC joint of the thumb. The patient will often manifest a weakened ability to grasp objects or perform such tasks as tying shoes and tearing a piece of paper. Other complaints include intense pain experienced upon catching the thumb on an object, such as when reaching into a pants pocket.
Many important activities of daily life are dependent on the ability to grasp, pinch, and oppose the thumb. In fact, thumb function constitutes about 50% of overall hand function. These abilities are in turn dependent on an intact and functional thumb CMC joint. The CMC joint of the thumb allows a wide range of motion while maintaining stability for grasp and pinch.
With this in mind, failure to properly recognize and treat the Bennett fracture will not only result in an unstable, painful, arthritic CMC joint with diminished range of motion: it will also result in a hand with greatly diminished overall function.
In the case of the Bennett fracture, the proximal metacarpal fragment remains attached to the anterior oblique ligament, which in turn is attached to the tubercle of the trapezium bone of the CMC joint. This ligamentous attachment ensures that the proximal fragment remains in its correct anatomical position.
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Wikipedia