Metacarpal Fracture
Reduction of a Boxer’s Fracture video 3D animation demonstrating the reduction (setting) of a boxer’s fracture (5th metacarpal neck fracture). Fractures of the First Metacarpal Base video 3D animation with narration describing Bennett’s and Rolando’s fractures. Metacarpal Fracture X-rays picture album X-rays of metacarpal fractures including post-reduction and post-operative x-rays. Boxer’s Fracture video 3D animation of a boxer’s fracture. Boxer’s Fracture picture album Several pictures illustrating 5th metacarpal fractures. 1st Metacarpal Fracture picture album Several pictures illustrating 1st metacarpal fractures.
Fractures at the base of the 1st metacarpal involve the carpometacarpal, or CMC, joint of the thumb.  This joint is very important in gripping and pinching.  A fracture through the base of the metacarpal can damage the joint, causing it to degenerate and become arthritic.  This is known as post-traumatic arthritis.  Two specific fracture patterns have been named.  Bennett's fracture involves the ulnar side of the metacarpal base.  Rolando's fracture is a "Y" or "T" shaped fracture of the metacarpal base that may be very comminuted, meaning that it is broken into many pieces. The CMC joint of the thumb has been described as two interlocking saddles.  This allows for movement in 2 planes.  Among the tendons that attach to the 1st metacarpal are the abductor pollucis longus and the adductor pollucis.  A Bennett's fracture may occur when a violent axial force is applied to the thumb in a slightly flexed position.  The abductor pollucis longus  has a tendency to pull the metacarpal down and out while the adductor pollucis pulls the head of the metacarpal in.  This results in slight dislocation (also known as subluxation) and displacement at the fracture site. Even fractures that initially appear nondisplaced may displace over time because of the tension applied by these tendons.  If the fracture is allowed to heal in this position, it can change the mechanics of the thumb and lead to arthritic changes.  The end result is a weak grip, poor range of motion, and chronic pain. Bennett's fractures are usually treated surgically.  The fracture can be pulled back into alignment either my making an incision and looking right at the bone or closed underneath a fluoroscope (which is like a small x-ray machine.)  Pins or screws are then used to hold the fragments in place.  Several different methods of placing the pins or screws are available depending on the nature of the fracture. Rolando's fractures have a worse prognosis, especially if they are very comminuted.  If there is a simple "T" or "Y" fracture, open reduction and internal fixation is a good option.  An incision is made over the fracture site.  The fracture is reduced, or pulled back into alignment.  A pin is used to hold the fragments in place along with reduction forceps.  A T-shaped plate is then applied and the pin removed. If the fracture is very comminuted, open reduction and internal fixation will likely not lead to a good outcome.  Instead, pins or an external fixator can be used to hold the metacarpal in place, allowing the many fragments to heal.  Even with appropriate treatment, Rolando's fractures may result in post-traumatic arthritis and chronic pain.  If so, the CMC joint can be fused.  This will eliminate the pain caused by the arthritic joint, but will result in limited range of motion.
The long bones of the hand are called the metacarpals.  There are 5 metacarpals -- one for  each finger.  An injury to the hand can break one or more of the metacarpals.  This is known as  a metacarpal fracture. Metacarpal fractures usually result from a traumatic blow to the hand.  Metacarpal fractures  may involve the head, neck, shaft, or base of the metacarpal.  Fractures of the 5th metacarpal  neck are especially common.  They typically occur with punching a hard object and are known  as boxer fractures. Metacarpal fractures are diagnosed based on a history, physical exam, and x-rays.  Patients  may report punching a wall or another traumatic blow to the hand.  Upon physical exam, the hand may be bruised and swollen.  The broken bone will, of course,  be tender to push on.  There may be a deformity at the fracture site.  The knuckle associated  with the broken metacarpal may be less prominent.  The fingers are inspected to look for  rotational deformities. X-rays are important not only to confirm that the hand is broken, but to evaluate the fracture.   Fractures may be non-displaced (just a crack) or displaced.  They may involve the cartilage in  the joints (intra-articular).  They may be angulated (bent at the fracture site).  Non-displaced metacarpal fractures can be treated without surgery.  A cast or splint is applied  to immobilize the affected fingers and limit motion across the fracture site.  This prevents the  broken fragment from displacing (moving out of place) and allows the fracture to heal.  The  fracture takes 4 to 6 weeks to heal. If the metacarpal fracture is displaced or angulated, it must be reduced.  This means that the  fracture is pushed back into alignment.  If a stable reduction can be obtained, a cast or splint is  applied to hold the fragments in place and allow the fracture to heal. If the fracture is too displaced or unstable, especially if it involves the joint surface, an adequate  reduction may not be possible to maintain without surgery.  Surgery sometimes involves  pushing the fracture fragments back into place and then drilling a pin through the skin and  across the fracture site to hold the fragments in position.  This is known as percutaneous  pinning or closed reduction-internal fixation (CRIF).  Pins are usually removed in the office in 3  to 5 weeks. Occasionally, the fracture cannot be successfully reduced without making an incision and  exposing the bone.  This is known as open reduction-internal fixation (ORIF).  Screws or plates  may be used to fix the fragments in place.  These are generally not removed.