What is it: Fractures involving the metacarpal bone are usually divided into neck, shaft and base fractures and treatment is dependent upon location.
How does it present: Fractures of the metacarpals are often due to punching something or a blow to the hand. Metacarpal neck fractures are classically from punching something and have therefore been termed "Boxer's Fractures." Patients will often have pain, swelling and discomfort over the injured area. They may complain of decreased grip strength.
Common exam findings: Exam should evaluate for location of tenderness, presence of crepitus or obvious deformity. In cases of metacarpal neck fractures, the knuckle of the associated metacarpal may be less prominent when the hand is in a closed fist position. Malrotation should also be evaluated for clinically. When the hand is in a closed fist position, with the fingers should all point in the same direction, generally towards the radial styloid. If one finger is angulated in the wrong direction, it is often overlapping other fingers and will cause problems with function if it remains malrotated. Fractures with evidence of malrotation will need manipulation and orthopedic evaluation. Neurovascular status should always be evaluated and documented.
Tests and treatment: X-rays should be sufficient to evaluate for metacarpal fractures. A lateral x-ray is needed to evaluate for angulation. Displaced fractures of the metacarpal bases will need manipulation and referral to orthopedics. Non-displaced fractures of the base of the second through fourth metacarpals can be treated with splinting and then casting in a short arm cast, checking closely for displacement, ulnar nerve injury and malrotation. Fractures at the base of the fifth metatarsal are quite unstable and should be referred to orthopedics for possible pin fixation. Treatment of metacarpal neck fractures also depends on which metacarpal is involved. Non-displaced and non-angulated fractures without shortening and malrotation can be treated by placing in a gutter splint and then casting with the wrist in 30 degrees of extension and the MCP in 70 to 90 degrees of flexion. Fractures of the fourth and fifth metacarpal necks can tolerate up to 30 and 40 degrees of angulation, respectively without requiring manipulation. Manipulation can be attempted to reduce the angulation, but is often hard to maintain. They should be splinted in a gutter splint or casted as above. Fractures of the second or third metacarpal necks are unable to tolerate much angulation due to the lack of compensatory motion at the CMC joint. Angulated fractures in this location should be splinted and referred to orthopedics. Similarly, management of fractures of the metatarsal shafts depends on which metacarpal is involved and how proximal the fracture is on the shaft. Less then 10 degrees of angulation is acceptable in fractures of the second and third metatarsal shafts and less than 20 degrees is acceptable for fourth and fifth metatarsal shafts. However, if the fracture is more proximal, even less angulation may be tolerated. Angulation greater than acceptable requires manipulation and consideration of referral to orthopedics. Non-angulated metatarsal shaft fractures without displacement, shortening or malrotation can be treated with gutter splinting or casting with the wrist in 30 degrees of extension and MCP flexed to 70 to 90 degrees. General length of immobilization for all of the metacarpal fractures is about four weeks.