Smith and Barton Fractures
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Direct answer
A Smith fracture is a reverse Colles fracture of the distal radius, with volar displacement of the distal fragment after a fall on a flexed wrist. A Barton fracture is an intra-articular shearing fracture of the distal radial rim with subluxation of the radiocarpal joint, most often volar. Barton fractures are usually fixed operatively with a plate because the articular rim cannot be held reliably by a cast.
What you must remember
- Smith fracture: extra-articular, with volar displacement and volar tilt of the distal fragment, giving the garden-spade deformity.
- Mechanism of Smith: a fall onto the back of a flexed wrist, which drives the distal fragment into volar displacement.
- Barton fracture: intra-articular, a rim fragment sheared off the radius with the carpus subluxing with it.
- Volar Barton: the commoner variant, in which the volar rim fragment and carpus displace volarly and proximally.
- Smith treatment: closed reduction and cast for stable patterns, with fixation when the fracture is unstable or intra-articular.
- Barton treatment: open reduction and internal fixation, usually with a volar buttress plate, because the rim is too small and too unstable for casting.
- Complications: median nerve compression, malunion, post-traumatic arthritis of the radiocarpal joint and tendon rupture.
Where the exam tries to catch you
Most lost marks come from calling a Barton fracture a simple Colles or from casting an unstable rim.
- Trap: a volar displaced distal radius fracture is a Colles fracture. Correct: volar displacement is a Smith fracture, the reverse of the dinner-fork Colles pattern.
- Trap: a Barton fracture is treated like a simple Colles with a cast. Correct: Barton is intra-articular with radiocarpal subluxation and usually needs open reduction and plating.
- Trap: a Smith fracture is always extra-articular and stable. Correct: most Smith fractures are extra-articular, but unstable patterns exist and may need fixation.
Frequently asked questions
How does a Smith fracture differ from a Colles fracture?
A Smith fracture displaces the distal fragment volarly after a fall on a flexed wrist, while a Colles fracture displaces it dorsally after a fall on an outstretched hand. The Smith fracture is therefore called a reverse Colles fracture, with a garden-spade deformity.
What is a Barton fracture?
A Barton fracture is an intra-articular shearing fracture of the distal radial rim, usually volar, with subluxation of the radiocarpal joint. The carpus moves with the rim fragment, so the joint surface is directly involved.
Why is plating usual for a Barton fracture?
Plating is usual for a Barton fracture because the articular rim is small and unstable, and a cast cannot hold it against the displacing force. A volar buttress plate restores the articular surface and supports the subluxing carpus.
Is a Smith fracture always treated with a cast?
A Smith fracture is not always treated with a cast, since stable extra-articular patterns can be reduced and casted, while unstable patterns need fixation. The decision depends on the stability of the reduction and on whether the joint is involved.