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Capitate fractures

Author
Kevin deWeber, MD, FAAFP, FACSM
Section Editors
Patrice Eiff, MD
Chad A Asplund, MD, FACSM, MPH
Deputy Editor
Jonathan Grayzel, MD, FAAEM

INTRODUCTION

The capitate is a major bone of the wrist that may be injured during falls onto an outstretched hand or from other trauma. This topic will review the presentation, diagnosis, and non-operative management of capitate fractures. General overviews of wrist pain and carpal fractures, as well as topics devoted to other specific carpal fractures in adults, are discussed separately. (See "Evaluation of the adult with acute wrist pain" and "Evaluation of the adult with subacute or chronic wrist pain" and "Overview of carpal fractures" and "Scaphoid fractures" and "Hamate fractures" and "Lunate fractures" and "Trapezoid fractures".)

EPIDEMIOLOGY

Hand fractures are among the most common of the extremity injuries, accounting for approximately 18 percent of all fractures. Carpal bone fractures comprise between 8 and 19 percent of hand fractures [1]. Fractures to the bones of the distal carpal row (trapezium, trapezoid, capitate, and hamate) are less frequent than fractures of bones in the proximal row (scaphoid, lunate, triquetrum, and pisiform). Capitate fractures account for approximately three percent of all carpal fractures, based primarily on large series in which computed tomography was used for definitive diagnosis [1-4].

CLINICAL ANATOMY

The capitate is the largest carpal bone. Distally, it articulates primarily with the base of the third metacarpal and a small portion of the fourth; radially with the trapezoid; proximally with the scaphoid and lunate; and on its ulnar side with the hamate (image 1 and figure 1 and figure 2 and figure 3). The capitate resembles the scaphoid in that its blood supply at the proximal pole is provided by vessels coursing distal to proximal, possibly increasing the risk of fracture complications from interruption of the blood supply. The anatomy of the wrist is reviewed in detail separately. (See "Anatomy and basic biomechanics of the wrist".)

MECHANISM OF INJURY

Capitate fractures occur from a number of mechanisms. Falls onto an outstretched hand and motor vehicle crashes are most commonly cited. Cadaver studies suggest that an injury sustained with the wrist in marked extension and radial deviation can cause the dorsal lip of the distal radius to contact the scaphoid, causing a fracture at its waist, and transmitting force to the capitate, which can fracture at its neck [5,6]. The following image depicts this relatively complex mechanism of injury (figure 4). Excessive palmar flexion during trauma may also predispose the capitate to injury [7]. Isolated fractures can occur from a dorsal blow or crush injury. Of note, injuries sustained from excessive palmar or dorsiflexion under a load (eg, falling onto an outstretched hand) may involve dislocations or fracture dislocations, and involve other carpal bones (eg, scaphoid). (See "Scaphoid fractures".)

Isolated capitate fracture is uncommon; concomitant carpal or metacarpal fractures and/or dislocations are much more common. In the largest series reported (53 capitate fractures), only 20 percent of capitate fractures were isolated [8]. The most common injury pattern reported is a "scaphocapitate syndrome." This hyperextension injury involves a force exerted on the radial styloid that causes fractures of both the scaphoid waist and proximal capitate. Depending upon the force, this injury can extend to perilunate dislocation, in which the proximal fragment of the capitate dislocates dorsally and rotates 180 degrees [9]. Other concomitant injuries can include fractures of the distal radius, hamate, metacarpal, or triquetrum most commonly; and the distal ulna, trapezoid, trapezium, lunate, pisiform, or phalanges less commonly [8]. (See "Evaluation of the adult with acute wrist pain", section on 'Perilunate and lunate dislocations'.)

               

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Literature review current through: Nov 2016. | This topic last updated: Wed Nov 16 00:00:00 GMT 2016.
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References
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