Smith Fracture Review

Excerpt

Smith fracture is an eponym for a distal radius fracture with volar displacement or angulation of the distal fragment. This condition is also known as a reverse Colles fracture since the more common Colles fracture features a dorsally displaced distal fracture fragment (see Image. Colles Fracture Versus Smith Fracture).

The wrist joint is a condyloid-type synovial joint. The distal tip of the radius and the articular disk (triangular ligament) of the distal radioulnar joint (DRUJ) articulate with the proximal carpal bones, except for the pisiform. The triangular fibrocartilage complex (TFCC) stabilizes the DRUJ and serves as a shock absorber in the wrist (radiocarpal) joint. The TFCC is composed of the triangular ligament, meniscus homolog, dorsal and volar radioulnar ligaments, ulnocarpal ligaments, and extensor carpi ulnaris (ECU) tendon sheath.

The ulna has a narrow attachment to the triangular ligament but not to any wrist bone, though it is a pivot point during pronation and supination. Most movement occurs around the radiocarpal articulation during flexion and extension.

A Smith fracture produces what is known as an "inverse dinner fork deformity." The median nerve and scaphoid bone can also get injured. The median nerve passes through the carpal tunnel anterior to the wrist. Median nerve injuries diminish hand sensorimotor function. Meanwhile, the scaphoid's poor vascularity predisposes it to slow healing, malunion, and nonunion. DRUJ and TFCC disruption may also complicate volar displacement of the distal radius, leading to pain and weakness on the ulnar side of the forearm and wrist.