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Abstract
A Bennett fracture is a common injury that involves an intra-articular fracture at the base of the first metacarpal. This fracture typically results in a dorsally and radially displaced metacarpal shaft relative to the well-anchored volar ulnar fragment. Most Bennett fractures are treated with operative fixation, including closed reduction and percutaneous fixation, open reduction and internal fixation, or arthroscopically assisted fixation. However, the optimal surgical approach is controversial. There is a paucity of literature comparing the outcomes of the various treatments, leaving the surgeon without a clear treatment algorithm. Moreover, there is no consensus on acceptable reduction parameters, including articular gap or step-off, with some series stating that up to 2 mm of displacement is acceptable.
Edward H. Bennett described the intra-articular fracture-dislocation of the first metacarpal base in 1882.1 He noted the thumb's functional importance, stating "no injury of it is to be lightly regarded."1 Injury to the first metacarpal frequently occurs, accounting for 25% of all metacarpal fractures, 80% of which involve the base, the Bennett fracture being most common.2 The goals of treatment are to maintain motion and the biomechanics of the trapeziometacarpal joint by restoring the joint's anatomic congruity and articular surface and correcting carpometacarpal subluxation or dislocation.3 Investigators postulate that accurate reduction of the CMC joint helps prevent the development of arthritis in an articulation already at increased risk.4,5 For non-displaced fractures, treatment in a thumb-spica cast can be tried.1,6,7 For displaced fractures, closed reduction and percutaneous pinning (CRPP) is preferred for small fragments with minimal articular step-off.8-10 Open reduction and internal fixation (ORIF) is often indicated for large fracture fragments with displacement greater than 2 mm that are irreducible with closed methods.2,4,5,11,12 Recently, investigators have described arthroscopic osteosynthesis of displaced Bennett fractures.13,14 More than 20 methods of treatment have been described, reflecting the lack of clear consensus on optimal treatment.15 The purpose of this article is to review the relevant anatomy, biomechanics, clinical evaluation, classification, treatment options, and controversies that exist for treatment of the Bennett fracture. We also present our preferred treatment methods given the available literature.
Anatomy
The trapeziometacarpal joint is unique in that it is a double "saddle" joint.3,16 The articular surfaces of the thumb metacarpal base and trapezium resemble reciprocally interlocking saddles,...