fractures of the metacarpal

introduction

this is one of the most common fracture presentations to the ED
accounts for ~10% of all hand fractures
commonly called “boxer's fracture” as this is usually caused by striking a solid object with a closed fist such as an untrained person's attempt to punch someone or an object using a “round-house” action
trained boxers generally use a “proper punch” with most of the impact passing through the stronger 2nd and 3rd metacarpals rather than the 5th metacarpal and thus generally do not sustain these fractures
less commonly, the neck of the 4th MC may be fractured as well as or instead of the 5th MC neck
these fractures remain unstable despite any attempts to reduce any angulation in the ED and as such this is not usually worthwhile attempting

Xray and diagnosis
any patients with compound injuries, particularly injuries over the MCP joint area should be considered at serious risk for infection particularly if there is a chance they could have been caused by impact with a recipient's tooth. Such injuries generally should be managed with iv antibiotics with coverage for oral flora and referred to plastic surgery that day for wash out in theatre.
patients with closed injuries may be placed in a volar slab and referred to plastic surgery within a week for consideration of ORIF, although some patients may elect to accept the minor deformity of loss of the 5th knuckle to avoid having the problems of K-wires interfering with their work, and risk of osteomyelitis.

may be caused by axial loading, direct blow or torsional loading producing either transverse, oblique or spiral fractures
remember to clinically examine for rotational deformity by flexing fingers and looking for mis-direction of the involved finger
displaced fractures with more than 3-4mm displacement or more than 10deg angulation, or any rotational deformity usually require reduction and thus referral to plastic surgery for ORIF
undisplaced or minimally displaced fractures may be managed with plaster slab or perhaps supportive stocking and elevation

caused by axial loading on the thumb
intra-articular fracture subluxation of the thumb carpometacarpal (CMC) joint
early diagnosis and referral to plastic surgery (usually for ORIF) is important to prevent long term morbidity

analagous to the Bennett's fracture except involving the 5th CMC jt
usually due to axial load
most mobile of the 4 ulnar CMC jts and thus most prone to arthrosis from articular incongruity
thus refer to plastic surgery for possible ORIF

may occur with or without fracture and usually require strong forces and thus there is a high risk of other injuries which should be sought
may be reduced in the ED and referred to plastic surgery for definitive management

may be reduced in the ED and referred to plastic surgery for definitive management