FRACTURES OF THE CARPAL BONES EXCLUDING THE SCAPHOID BY MUNIR A. SHAH, MD, AND STEVEN F. VIEGAS, MD Carpal fractures excluding the scaphoid can cause morbidity that is dispropor- tionate to their incidence because they are easily overlooked and are often harbingers of a wider wrist injury. Failure to recognize a more global injury pattern can result in undertreatment and permanent wrist dysfunction. Diagnosis requires a high index of suspicion,familiarity with carpal topography to guide the physical examination,and judicious use of specialized radiographic views and ancillary imaging techniques. Copyright © 2002 by the American Society for Surgery of the Hand racture of the carpal bones, excluding the topography to guide the physical examination and scaphoid, account for approximately 40% of judicious use of specialized radiographic views and Fall carpal fractures.1 Paradigms for evaluation ancillary imaging techniques based on clinical sus- and treatment of the fractured scaphoid are well picion. Second, such fractures are often harbingers delineated in the literature. The less common frac- of significant ligamentous disruption or associated tures of other carpal bones have received consider- carpal fractures. Failure to recognize a more global ably less attention. However, these injuries can injury pattern can result in undertreatment and produce morbidity that is disproportionate to their permanent wrist dysfunction. incidence for several reasons. First, carpal fractures We examine the incidence, mechanisms of injury, excluding the scaphoid may have a subtle clinical associated osseous and ligamentous injuries, physical and radiographic presentation and are easily over- examination findings, useful radiographic views, and looked. Diagnosis requires familiarity with carpal ancillary imaging techniques and management prin- ciples of these often overlooked carpal fractures. From the Division of Hand Surgery,Department of Orthopaedics and Rehabilitation,University of Texas Medical Branch,Galveston, TRIQUETRUM TX. Address reprint requests to Munir A. Shah,MD,Department of Orthopaedics,Rebecca Sealy Hospital,Room 2.616,301 University riquetral fractures are probably the most com- Blvd,Galveston,TX 77555-0165. E-mail: [email protected] Tmon carpal fracture excluding the scaphoid. In a population-based study conducted in Bergen, Nor- Copyright © 2002 by the American Society for Surgery of the Hand 1531-0914/02/0203-0003$35.00/0 way, triquetral fractures comprised 31% of all carpal doi:10.1053/jssh.2002.34795 fractures.1 JOURNAL OF THE AMERICAN SOCIETY FOR SURGERY OF THE HAND ⅐ VOL. 2,NO. 3,AUGUST 2002 129 130 CARPAL FRACTURES (EXCLUDING SCAPHOID) ⅐ SHAH & VIEGAS Triquetral fractures can involve the dorsal rim or body.2 Fractures of the dorsal rim can result from avulsion of the dorsal intercarpal, dorsal radiocar- pal, or lunotriquetral ligaments during a hyperflex- ion/radial deviation injury to the wrist. Alterna- tively, hyperextension/ulnar deviation injuries can produce an impaction fracture when the ulnar styloid or hamate chisel into the dorsal triquetral rim (Fig 1).3,4 Triquetral body fractures most commonly involve the medial tuberosity, typically caused by a direct blow to the ulnar border of the wrist. Other fracture patterns involving the body include comminuted, transverse, or sagittal fractures and are commonly associated with higher energy mechanisms of injury. Triquetral body fractures may be the sole radiographic manifestation of a more global wrist injury including axial disruption of the carpus secondary to severe dorsopalmar crush or a perilunate greater arc injury (Fig 2).5,6 Physical examination reveals dorsoulnar wrist ten- derness over the triquetrum. Standard wrist radio- graphs are typically diagnostic. The oblique view is the most useful for visualizing dorsal rim fractures.2 Occasionally, bone scan or computed tomography (CT) may be necessary to corroborate clinical suspi- cion. Cast immobilization is sufficient for dorsal avul- sion/chisel fractures and nondisplaced fractures of the triquetral body if carpal instability has been excluded. Patients should be counseled that dorsal rim fractures may produce prolonged soreness.2 In addition, pro- gression to symptomatic nonunion may occur and can be treated with fragment excision and ligament repair. Isolated, nondisplaced body fractures can be treated with cast immobilization. Triquetral body fractures that are displaced or are part of a broader ligamentous insult require surgical treatment to reduce and stabi- lize the fracture and, when necessary, address carpal instability.6-8 HAMATE FIGURE 1. Mechanisms of triquetral avulsion fractures. amate fractures constitute approximately 7% of (CMC) joints (Fig 3).9 The typical mechanism is axial Hcarpal fractures and can involve the hamular loading of the flexed CMC joints (eg, striking an process (hook) or, more commonly, the body.1 Body unyielding object with a clenched fist), that produces fractures are typically associated with a broader hand a coronally oriented fracture of the dorsal, distal and/or wrist injury, most commonly dorsal fracture hamate with variable degrees of comminution.10 Body dislocation of the 4th and/or 5th carpometacarpal fractures also may be associated with greater arc peri- CARPAL FRACTURES (EXCLUDING SCAPHOID) ⅐ SHAH & VIEGAS 131 FIGURE 2. (A) Anteroposterior wrist radiograph shows a seemingly isolated triquetral fracture (arrow). However, there is disruptions of Gilula’s arcs, a minute fleckavulsion from the radial styloid and palmar flexion of the lunate as evidenced by its triangular radiographic appearance. (B) Lateral wrist radiograph shows a dorsal perilunate dislocation. Triquetral fractures can represent an osseous component of a wider ligamentous injury. lunate injuries or axial carpal dislocations.8 The latter often, over the dorsal aspect of the hamate.12-14 Pain injury is associated with dorsopalmar crush and flat- can be elicited with resisted ring and small finger tening of the carpal arch, which produces sagittal- distal interphalangeal joint flexion when the wrist is oblique hamate body fracture.5 in ulnar deviation (Fig 4). Pain is relieved when the Fractures of the hamular process are typically iso- test is performed with the wrist in radial deviation.15 lated injuries. The mechanism of injury is classically Patients with delayed presentation may have flexor direct trauma to the patient’s nondominant hand by tendon rupture that should be specifically excluded the base of a golf club, bat, or racquet.10-13 Falls on an during the initial examination. Patients with hamular outstretched hand can also produce hook fractures, process and hamate body fractures require a thorough either by direct trauma or flattening of the carpal arch evaluation of ulnar nerve function, particularly the with avulsion by the transverse carpal ligament. The deep motor branch, because both injuries can be as- hook of the hamate may fracture at the tip, waist, or sociated with ulnar neuropathy. Associated carpal tun- base. nel syndrome has also been reported.12,13 Physical examination of the typical body fracture Hamate body fractures are usually apparent on (CMC joint fracture dislocation) reveals dorsoulnar standard wrist radiographs, particularly the oblique wrist swelling. Tenderness is well localized to the and lateral views.16 When associated with a fracture CMC joints. Loss of knuckle prominence from abnor- dislocation of the CMC joints, the metacarpals are mal flexion of the metacarpal(s) or abrasions over the usually flexed, with their bases residing in an abnor- metacarpal heads may be present. Poorly localized mal dorsal position and relative to the intact carpus tenderness should alert suspicion for additional liga- and adjacent metacarpals. Hamular process fractures mentous disruptions, particularly in patients with are notoriously difficult to visualize with standard a history of high-energy injury (eg, dorsopalmar radiographs. The carpal tunnel and 30° supinated crush).5 oblique views are valuable additional radiographic In contrast, patients with hook of the hamate frac- projections that may visualize hook of hamate frac- tures may have a subtle initial presentation, and the tures (Fig 5).13,17 Transverse CT images or bone scan injury can be easily overlooked. Diagnosis requires a should be obtained if the diagnosis remains in ques- high index of suspicion. Patients may complain of tion.18 poorly localized palmar wrist pain aggravated by Nondisplaced, isolated hamate body fractures may power grip.13 Examination reveals tenderness over the be treated with immobilization. More commonly, hamular process (radial and distal to the pisiform) and, these fractures are part of a larger injury, and surgical 132 CARPAL FRACTURES (EXCLUDING SCAPHOID) ⅐ SHAH & VIEGAS FIGURE 3. Fracture-dislocations of the 4th and 5th CMC joints often have minimal findings on the (A) anteroposterior wrist radiograph except increased overlap of the 5th metacarpal and hamate. The (B) oblique and (C) lateral views show a flexed posture of the 5th metacarpal, abnormal dorsal prominence of the metacarpal bases and a coronally oriented fracture of the dorsal, distal hamate (C, arrow). Postoperative (D) anteroposterior and (E) lateral wrist radiographs show reduction of the CMC joints and restoration of hamate articular congruity. A dorsal, coronally oriented capitate fracture resulted from this injury because the capitate has a facet for articulation with the 4th metacarpal. This patient had a complete, preoperative motor