INTRODUCTION — This topic reviews issues related to fractures of the trapezoid. General overviews of wrist pain and carpal fractures, as well as topics devoted to other specific carpal fractures in adults, are presented 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 perilunate injuries" and "Capitate fractures" and "Pisiform fractures" and "Triquetrum fractures" and "Trapezium 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 upwards of 8 percent of hand fractures [1]. Fractures to bones of the distal carpal row, consisting of the trapezium, trapezoid, capitate, and hamate, are less frequent than fractures of bones in the proximal row (scaphoid, lunate, triquetrum, and pisiform).

The trapezoid is the carpal bone least often fractured, comprising approximately 2 percent of all carpal fractures [1-4]. Trapezoid fractures usually occur in association with other injuries, most commonly fracture of the hamate, capitate, trapezium, or metacarpals [5]. (See 'Differential diagnosis' below.)

PERTINENT ANATOMY — Anatomy of particular relevance to trapezoid fractures is discussed below. A detailed discussion of wrist anatomy is provided separately. (See "Anatomy and basic biomechanics of the wrist".)

The location and shape of the trapezoid convey relative protection, hence the rarity of isolated injury. The trapezoid lies in the distal carpal row and articulates distally with the second metacarpal base, radially with the trapezium, ulnarly with the capitate, and proximally with the scaphoid (image 1 and figure 1 and figure 2). It is keystone shaped, with a dorsal width twice its palmar width. It forms a stable and relatively immobile articulation with the second metacarpal and has strong ligamentous attachments to adjacent carpal bones.

The trapezoid is palpable on the dorsal wrist at the base of the second metacarpal but difficult to distinguish from this metacarpal. It can be located by starting palpation at the distal aspect of the anatomical snuffbox, then moving in an ulnar direction approximately 1 to 2 cm (picture 1).

MECHANISM OF INJURY — Fractures of the trapezoid generally occur with axial loading of the second metacarpal, high-energy trauma, crush injury, or forced wrist flexion or extension [5]. In sport, such forced wrist flexion or extension can occur when a player dives for a ball or opponent with an outstretched arm. Isolated fracture of the trapezoid is unusual [5,6]. More common is dorsal dislocation or concomitant carpal or metacarpal fractures. With axial loading, the wedge-like trapezoid, with its narrowest width at the volar aspect, slips in a dorsal direction. Axial compression also transmits forces to the adjacent scaphoid [7].

SYMPTOMS AND EXAMINATION FINDINGS — The patient with a trapezoid fracture typically presents with radial-dorsal wrist pain. Patients usually have some degree of swelling, and possibly ecchymosis, along the dorsum of the hand; and point tenderness dorsally just proximal to the second metacarpal base (picture 1). Resisted wrist dorsiflexion may cause pain, as the extensor carpi radialis passes over the trapezoid and inserts on the proximal aspect of the second metacarpal.

Examination of surrounding structures is important, as trapezoid fractures are often associated with concomitant injury to other bones, ligaments, tendons, vasculature, and nerves. Concurrent injury is present in over 90 percent of trapezoid fractures. Common associated injuries include fractures of the hamate and metacarpals, as well as the capitate, trapezium, and adjacent phalanges.

In addition to bony palpation, radial artery integrity should be evaluated with palpation of the pulse at the wrist, assessment of color and capillary refill in the fingers, and the Allen test (picture 2). Superficial radial nerve assessment should include testing of the sensation along the radial dorsum of the hand. Median nerve assessment should include testing of the palmar sensation of all digits from the thumb to the ring finger, and the strength of thumb flexion, abduction, and opposition.

RADIOGRAPHIC FINDINGS — Trapezoid fractures often evade detection with plain radiographs, but nevertheless, imaging should begin with standard anteroposterior (AP), lateral, and oblique views of the wrist (image 2). These views are helpful in assessing for dislocation. The AP or oblique views may detect sagittal trapezoid fractures but should not be relied on.  

Studies using computed tomography (CT) as the reference standard have reported that plain radiographs demonstrate poor sensitivity and specificity for detecting trapezoid fractures [2,3]. Plain radiography identified none of four trapezoid fractures in one retrospective series of 137 carpal fractures [3], while another study of 103 consecutive patients with wrist trauma reported that plain radiography failed to identify any of the three trapezoid fractures amongst 38 carpal fractures [2]. Other small retrospective case series have reported 33 [6] to 64 percent [5] sensitivity with plain radiography. Therefore, if plain radiographs are unrevealing but clinical suspicion persists, a CT scan or magnetic resonance imaging (MRI) should be obtained.

A CT scan is highly accurate for identifying fracture or dislocation and for assessing joint surfaces when there is any question of intra-articular fracture with displacement. MRI has additional value in detecting both acute and chronic bony and soft tissue injuries. If significant soft tissue injury (eg, ligament rupture or dislocation) is suspected, MRI should be obtained (image 3A-C).

DIAGNOSIS — The diagnosis of trapezoid fracture may occasionally be made by plain radiography, in conjunction with a suggestive history and examination findings. However, as plain radiographs demonstrate poor sensitivity for these injuries, computed tomography (CT) or magnetic resonance imaging (MRI) is usually needed when fracture is suspected but initial radiographs are normal and a definitive diagnosis is required. In addition, advanced imaging is useful for detecting the concomitant injuries that are frequently present.

DIFFERENTIAL DIAGNOSIS — Diagnoses that may coincide with or be confused with a trapezoid fracture include those described below. The differential diagnosis for acute wrist pain is discussed in detail separately. (See "Evaluation of the adult with acute wrist pain" and "Evaluation of the patient with thumb pain".)

Fracture of the trapezium, capitate, scaphoid, or other carpal bones — Radial-sided wrist pain following trauma may be due to fracture of the scaphoid (the most commonly fractured carpal bone), trapezium, capitate, or any combination of these bones. One large, retrospective series found that 95 percent of trapezoid fractures are associated with concurrent wrist injuries [6]. Tenderness may be diffuse at the radial aspect of the wrist. Snuffbox tenderness (figure 3 and picture 3) is suggestive but not diagnostic of scaphoid fracture (note that the trapezium also lies at the distal end of the snuffbox). Diagnostic imaging to identify such fractures should include standard wrist and scaphoid views (image 4), but advanced imaging is frequently required for definitive diagnosis. (See "Overview of carpal fractures" and "Scaphoid fractures" and "Trapezium fractures" and "Capitate fractures".)

Distal radius fracture — This most common fracture of the wrist and hand is usually sustained from a fall onto an outstretched hand. Tenderness is present at the distal radius, sometimes accompanied by deformity and ecchymosis. Diagnosis is generally made with plain radiographs. Approximately 7 percent of radial fractures have a concomitant carpal fracture, so the clinician should perform a careful search for these injuries [8]. (See "Distal radius fractures in adults".)

Fractures and fracture-dislocations of the second metacarpal — Fracture of the second metacarpal is suggested by pain and dorsal swelling over the base of the bone along its dorsal aspect. Dislocation of the trapezoid may be concomitant. Standard radiographs of the wrist (anteroposterior [AP], lateral, oblique) are typically sufficient for diagnosis, but computed tomography (CT) can be useful to define the position of fragments. (See "Evaluation of the patient with thumb pain".)

Dislocation of the trapezoid — Isolated trapezoid dislocation is rare. Due to the wedge shape of the trapezoid and its wider dorsal dimension, dislocation is usually dorsal. Dislocation causes swelling and possibly gross deformity at the dorsal wrist, and pain at the base of the second metacarpal. Plain radiographs detect some dislocations, but CT may be required. A careful search for concomitant fracture should be performed, as such injury is likely. In addition, a careful neurovascular examination should be performed. Any diminished or absent radial pulse or signs of impaired circulation to the hand should prompt immediate surgical referral for reduction [7].

INDICATIONS FOR SURGICAL REFERRAL — Open fractures and those associated with neurovascular compromise require emergency (ie, immediate) surgical consultation. Any trapezoid fracture associated with comminution, displacement, or dislocation should be referred to a hand surgeon [9-11].

What constitutes significant displacement remains unclear. While one case report describes a fracture with up to 2 mm displacement that was successfully treated nonoperatively [12], another describes a coronal fracture with 1 mm displacement that failed conservative treatment [6]. We suggest referral to a hand surgeon for any degree of fracture displacement.

Dislocations increase the risk of neurovascular injury and long-term complications, and fractures associated with a dislocation should be urgently referred. Even if the hand surgeon cannot see the patient immediately, the case should be discussed with the consulting surgeon by phone as soon as the dislocation is recognized. Primary care clinicians skilled in reducing dislocations may attempt reduction of a dorsally dislocated trapezoid prior to referral. (See 'Initial treatment' below.)

As nearly all trapezoid fractures are associated with other wrist injuries, the clinician should look carefully for such injuries. Once they are identified, the clinician must consider whether indications for referral are present. The presence of multiple injuries lowers the threshold for referral.

INITIAL TREATMENT — Primary care clinicians with experience managing fractures may elect to manage the patient with an isolated, noncomminuted, nondisplaced trapezoid fracture.

Primary care clinicians skilled in reducing dislocations may attempt reduction of a dorsally dislocated trapezoid prior to referral. Reduction can be performed by applying gentle traction to the second metacarpal, followed by simultaneously flexing the wrist and placing direct pressure on the dorsal side of the trapezoid [9]. Following reduction, a volar splint should be applied. If the reduction cannot be maintained, the patient is referred. (See 'Indications for surgical referral' above.)

Treatment of trapezoid fractures is based on expert opinion, as these fractures are rare and the literature is limited to small case reports. It is reasonable to treat isolated, nondisplaced sagittal or coronal linear fractures conservatively with immobilization in a short arm cast (picture 4), once initial swelling has subsided, for four to six weeks [10,11,13,14]. If marked swelling is present initially, a volar splint can be applied for three to five days (figure 4) while ice and elevation are used to reduce such swelling. (See "Basic techniques for splinting of musculoskeletal injuries" and "General principles of definitive fracture management", section on 'Casting'.)

FOLLOW-UP CARE — The patient should be assessed for cast integrity after approximately three weeks, or as needed should symptoms of poor cast fit develop. Biweekly cast checks may be prudent in very active patients. When the cast is removed, healing should be confirmed clinically by the absence of point tenderness. Following four to six weeks of immobilization, plain radiographs should be repeated after cast removal. Displacement can occur following the initial visit, so careful reassessment is important.

Particularly for patients who sustained a fracture-dislocation, it is important to assess for signs of osteonecrosis from disruption of the blood supply to the trapezoid. Signs may consist of persistent pain and changes in the appearance of the bone on plain radiograph, which may not be apparent for several weeks after the injury. Such findings warrant referral to a hand surgeon. (See 'Dislocation of the trapezoid' above and 'Indications for surgical referral' above.)

After four to six weeks of casting, the wrist will have lost strength and mobility. Depending on the clinical circumstances, formal physical or occupational therapy, or a home exercise program, can be used to help the patient regain full function. The patient can stop the program once full mobility and strength are regained.

A basic home exercise program might consist of the following:

●Perform passive stretches twice daily, holding each stretch for 30 seconds. Stretch the wrist in flexion, extension, ulnar deviation, and radial deviation. The hand and wrist can be soaked in very warm water for five minutes prior to stretching to facilitate motion.

●Perform motion and strength exercises after stretching. Exercises should include active wrist circles 10 times in each direction followed by two sets of 15 repetitions using appropriate resistance (eg, elastic band, dumbbell) for each of the following: wrist flexion, wrist extension, ulnar deviation, and radial deviation.

The patient's pain, motion, and function should be assessed about two weeks after cast removal. Those who are having persistent, significant pain and/or functional impairment may benefit from a referral to physical therapy.

COMPLICATIONS — Delayed union, nonunion, and post-traumatic arthritis are possible complications of trapezoid fracture, especially if diagnosis is delayed. Dorsal dislocations may disrupt the dorsal blood supply to the trapezoid, possibly resulting in osteonecrosis [9-11]. As trapezoid fractures are uncommon, data pertaining to their complications are limited, but they appear to be uncommon.

RECOMMENDATIONS FOR RETURN TO SPORT OR WORK — If the patient can perform their work or sport while wearing rigid joint protection (ie, cast), they may proceed with their activities as tolerated during immobilization. Semirigid protection in a brace should be continued for four weeks after rigid immobilization is completed. Unprotected return to full sport or heavy physical labor requires full wrist range of motion and at least 80 percent strength compared with the uninjured extremity. If operative treatment is required, sport and work may resume at approximately 12 weeks postoperatively [9].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Fractures of the skull, face, and upper extremity in adults" and "Society guideline links: Acute pain management".)

SUMMARY AND RECOMMENDATIONS

●Isolated fractures of the trapezoid are rare. Fractures generally occur with axial loading of the second (index) metacarpal or may occur secondary to direct dorsal wrist trauma or forced flexion or extension of the wrist. Concomitant injury, including other carpal fractures and ligament injuries, is common. (See 'Epidemiology' above and 'Mechanism of injury' above.)

●Patients with a trapezoid fracture typically present with radial-dorsal wrist pain and some degree of swelling along the dorsum of the hand. Point tenderness dorsally just proximal to the second metacarpal base is common. (See 'Symptoms and examination findings' above.)

●Standard radiographic views of the wrist may not be sufficient for diagnosis. Oblique projections or computed tomography (CT) scan may be necessary for identification of the fracture. Magnetic resonance imaging (MRI) may be needed to diagnose soft tissue injury. (See 'Radiographic findings' above.)

●The differential diagnosis for trapezoid fracture includes other carpal bone fractures, distal radius fracture, fracture or fracture-dislocation of the second metatarsal, and dislocation of the trapezoid. (See 'Differential diagnosis' above.)

●Indications for immediate surgical referral include open fracture, fracture associated with neurovascular compromise, and carpal dislocation. Any trapezoid fracture associated with comminution, displacement, or dislocation should be referred to a hand surgeon. (See 'Indications for surgical referral' above.)

●Nondisplaced fractures without comminution or significant associated injury can be managed by primary care clinicians and are treated adequately with a short arm cast for four to six weeks followed by removable splinting while range of motion and strength return. (See 'Initial treatment' above and 'Follow-up care' above.)