Overview of carpal fractures

INTRODUCTION — The carpals are the bones of the wrist between the radius and ulna proximally, and the metacarpals distally. These eight bones are collectively termed the carpus and are commonly divided into the proximal carpal row—scaphoid, lunate, triquetrum, and pisiform—and the distal row—trapezium, trapezoid, capitate and hamate. In general, carpal fractures occur from either direct or indirect trauma.

This topic provides an overview of basic carpal anatomy, mechanisms of injury, general principles of examination and imaging, and the initial care of adults with carpal fractures. More detailed discussions of common and important wrist injuries are presented separately. (See "Evaluation of the adult with subacute or chronic wrist pain" and "Evaluation of the adult with acute wrist pain" and "Distal radius fractures in adults" and "Scaphoid fractures" and "Triquetrum fractures" and "Lunate fractures and perilunate injuries" and "Capitate fractures" and "Hamate fractures".)

EPIDEMIOLOGY— Hand fractures are among the most common of extremity injuries, accounting for about 18 percent of all fractures. Carpal fractures comprise upwards of 8 percent of hand fractures [1-3]. Scaphoid fractures are by far the most common of the carpal fractures, and account for 10 percent of all hand fractures and about 55 percent of all carpal fractures [1,4-8]. The triquetrum is the second most common carpal fracture, comprising about 21 percent. Fractures of the hamate, lunate, capitate, trapezium, pisiform, and trapezoid follow in prevalence, in that order, ranging from 2 to 7 percent of carpal fractures [1,6-8].

CLASSIFICATION AND CLINICAL PRESENTATION — Carpal fractures are classified primarily by the anatomic location of the fracture (see 'Clinical anatomy' below) and secondarily based upon the features of the injury, including associated displacement, dislocation, and the number of fragments produced by the fracture (comminuted versus noncomminuted).

It is important to note that a significant proportion of carpal fractures involve multiple carpal bones, so if one carpal is fractured, the clinician should search for others.

Isolated fractures through the distal radius or ulna, although described in lay terms as "wrist fractures," do not involve the carpal bones. (See "General principles of fracture management: Bone healing and fracture description".)

Brief description of fractures — Issues related to fractures of the eight carpal bones (image 1) are discussed separately in the appropriate topic reviews that are listed below:

●Fracture of the scaphoid (image 2) ‒ The scaphoid is the most commonly fractured carpal bone, accounting for 55 percent of all carpal fractures. The most common mechanism involves a fall onto an outstretched hand with the wrist extended and radially deviated. Patients typically present with radial sided wrist pain, swelling, limited range of wrist motion, tenderness in the anatomic snuff box (figure 1), and pain with axial loading along the thumb. The diagnosis and management of scaphoid fractures are discussed separately. (See "Scaphoid fractures".)

●Fracture of the lunate (image 3) ‒ Acute lunate fractures most often occur from a fall onto an extended wrist, or from some other type of wrist hyperextension injury. Patients typically present with wrist pain that is aggravated by wrist motion or gripping. Because of the intracapsular location of the lunate, swelling may be minimal. If presentation is late, stiffness or decreased range of motion of the wrist may be the only complaint. The diagnosis and management of lunate fractures are discussed separately. (See "Lunate fractures and perilunate injuries".)

●Fracture of the triquetrum (image 4) ‒ Triquetrum fractures are the second most common carpal bone fracture and are usually ligamentous avulsion fractures. The patient typically presents with a history of trauma and pain at the ulnar aspect of the wrist. On examination, there is generally point tenderness either dorsally (picture 1) or along the distal ulnar border of the wrist. The diagnosis and management of triquetrum fractures are discussed separately. (See "Triquetrum fractures".)

●Fracture of the pisiform (image 5) ‒ Most commonly, the pisiform is injured in a fall onto an outstretched hand with the wrist in extension, or when the heel of the hand is used like a hammer. Patients typically present with pain and swelling at the palmar and ulnar aspects of the wrist. Tenderness is present at the pisiform (picture 2) and over the hypothenar eminence. The diagnosis and management of pisiform fractures are discussed separately. (See "Pisiform fractures".)

●Fracture of the trapezium (image 6) ‒ Trapezium fractures often occur from a fall onto an outstretched hand. The patient typically presents with minimal swelling but may have significant discomfort (more than expected from other carpal bone fractures). There is pain and weakness with pinching (eg, making an "OK" sign, or touching the thumb to the tip of the little finger). The diagnosis and management of trapezium fractures are discussed separately. (See "Trapezium and trapezoid fractures".)

●Fracture of the trapezoid (image 7) ‒ Fractures of the trapezoid generally occur from axial loading of the second (index) metacarpal, or may rarely occur as a result of direct dorsal trauma. Patients usually present with some degree of swelling on the dorsum of the hand, and point tenderness dorsally just proximal to the second metacarpal base (picture 3). The diagnosis and management of trapezoid fractures are discussed separately. (See "Trapezium and trapezoid fractures".)

●Fracture of the capitate (image 8) ‒ The capitate is the largest carpal bone. Isolated capitate fractures typically result from falling on a clenched fist. The patient presents with pain and swelling at the dorsum of the hand. There is usually tenderness dorsally over the area of the capitate (just proximal to the third metacarpal). The diagnosis and management of capitate fractures are discussed separately. (See "Capitate fractures".)

●Fracture of the hamate (image 9) ‒ Hamate fractures can involve either the hook or the body of the bone. Hook fractures are more common and result from a fall onto an outstretched hand or swinging sports, such as tennis, golf, or baseball, during which the base of the racquet or club handle can injure the bone. Patients present with tenderness deep in the palm over the hook of the hamate (picture 4). The diagnosis and management of hamate fractures are discussed separately. (See "Hamate fractures".)

CLINICAL ANATOMY — A detailed discussion of wrist anatomy is provided separately. (See "Anatomy and basic biomechanics of the wrist".)

There are eight carpal bones that comprise approximately 3 cm of the proximal hand (image 1). The carpal bones are subdivided into a proximal and distal row.

The proximal row carpal bones (from radial to ulnar) are:

●Scaphoid

●Lunate

●Triquetrum (dorsal)

●Pisiform (volar)

The distal row (from radial to ulnar) is comprised of the:

●Trapezium

●Trapezoid

●Capitate

●Hamate

MECHANISM OF INJURY — If the patient can describe the way in which the wrist was injured, this may suggest which of the carpal bones has/have been injured and affect decisions about initial imaging studies [2,3,9]. Note that the descriptions below involve only carpal bone fractures and these mechanisms may result in other injuries (eg, fall onto extended wrist causing distal radius fracture).

Axial loading — Axial loading of the wrist may cause fractures of the scaphoid and can result in disruption of the scapholunate ligaments, resulting in scapholunate dissociation (image 10). Axial loading of the first metacarpal (thumb) is associated with vertical intra-articular fractures of the trapezium, while axial loading of the index metacarpal is associated with fracture of the trapezoid, with which it articulates. (See "Evaluation of the adult with acute wrist pain", section on 'Scapholunate instability' and "Trapezium and trapezoid fractures".)

Wrist hyperextension — An injury involving hyperextension of the wrist, as can occur with a fall onto an outstretched hand, can force the scaphoid over the dorsum of the radius leading to fracture (image 2). The lunate and triquetrum may also be fractured due to hyperextension injuries. (See "Scaphoid fractures" and "Lunate fractures and perilunate injuries" and "Triquetrum fractures".)

A linear fracture of the pisiform may occur due to a fall onto the hand but this injury is more likely due to a direct blow to the bone itself rather than wrist hyperextension. Less commonly, hyperextension of the wrist may cause an avulsion fracture of the pisiform, typically at the distal attachment of the flexor carpi ulnaris tendon. (See "Pisiform fractures".)

Wrist hyperflexion — Hyperflexion of the wrist may cause avulsion fractures involving the ligamentous attachments to the triquetrum. (See "Triquetrum fractures".)

Deviation, traction, or rotation — Injury due to forceful deviation, traction or rotation of the wrist, or of the first metacarpal, may cause ligamentous or capsular stresses that can result in avulsion fractures of any of the carpal bones.

Direct blow to the palmar surface — Compression of the pisiform against the triquetrum due to a direct blow (as when the hand is used as a hammer) may result in a pisiform fracture or cause chondral damage to the dorsal articular surface of the pisiform bone. (See "Pisiform fractures".)

The hook of the hamate is also vulnerable to direct pressure upon the transverse carpal ligament, which can avulse the hook from the body of the hamate. The hamate can also sustain a fracture from a fall onto the hand or a force transmitted by the end of a club, racquet, or bat that is pressed against the hamate hook. (See "Hamate fractures".)

Combinations of forces — The combination of axial loading and hyperflexion or hyperextension, as may occur with falling onto a clenched fist, can result in capitate fractures, often with associated dislocation. (See "Capitate fractures".)

SYMPTOMS AND EXAMINATION FINDINGS — Important questions when evaluating the patient with acute wrist pain include the location of the pain, the patient's dominant hand, their occupation or sport, and which movements exacerbate pain. The presentation and history-taking of patients presenting with wrist pain are discussed in detail separately. (See "Evaluation of the adult with acute wrist pain" and "Evaluation of the adult with subacute or chronic wrist pain".)

The location of pain and tenderness helps to determine which bone or bones are most likely to have been injured and can guide requests for imaging studies (image 1 and figure 2 and figure 3). Tenderness in the anatomic snuffbox (picture 5 and figure 1) suggests a scaphoid injury but may also indicate a trapezium or distal radius injury. Palpation of the Lister tubercle on the dorsal radius (figure 2 and picture 6) is helpful for locating the scapholunate articulation, which is located just distal to the tubercle. Palmar-predominant pain is more likely to involve the pisiform (at the base of the hypothenar eminence (picture 2)) or hamate hook (within the hypothenar eminence (picture 4)), or the distal, volar pole of the scaphoid at the base of the thenar eminence (picture 7).

After carpal fracture, the ensuing pain often causes a reduction in wrist motion and in the strength of wrist flexion and extension, and hand grip. Neurovascular function should be assessed, as fractures and dislocations can damage adjacent nerves or blood vessels. Any possible fracture with neurovascular compromise warrants emergency treatment and consultation with hand surgery. Other specific examination tests are discussed in detail in topics devoted to specific fractures.

IMAGING

Plain radiographs — When a carpal fracture is suspected, standard plain radiographs should be obtained. However, plain radiographs are insensitive, detecting fewer than half of all carpal fractures [6,7]. The standard wrist radiograph series includes posteroanterior (PA) (image 1), oblique (picture 8), and true lateral (image 11) views. Other views are indicated depending upon the suspected site of the fracture; these additional views are discussed in more detail in the topics devoted to specific injuries. Summarized briefly, the following additional plain radiographs may be informative in certain situations:

●A scaphoid view (PA view of the wrist with maximal ulnar deviation) is useful for suspected scaphoid fractures (image 12). (See "Scaphoid fractures".)

●A carpal tunnel view is useful for identifying fractures of the hook of the hamate (image 9). (See "Hamate fractures".)

●A PA clenched fist view is helpful in demonstrating scapholunate instability caused by rupture of the scapholunate ligament. The space between carpal bones is usually 2 to 3 mm and a space of more than 3 mm suggests ligamentous disruption (image 13) [10]. (See "Evaluation of the adult with acute wrist pain", section on 'Scapholunate instability'.)

●A Bett view (anteroposterior, with approximately 20 degrees of pronation) can help to identify trapezium fractures when suspected clinically.

Computed tomography and magnetic resonance imaging — The sensitivity of plain radiographs for detecting carpal fractures is poor – less than 50 percent for most carpal bones [6,7]. Therefore, if radiographs are unrevealing but clinical suspicion of a fracture persists (eg, bony tenderness and a plausible mechanism of injury), a computed tomography (CT) or magnetic resonance imaging (MRI) study should be obtained. CT is highly accurate for identifying carpal fracture or dislocation, and for assessing joint surfaces when there is a question of intra-articular displacement [11]. MRI has additional value in detecting both acute and chronic bony and soft tissue injuries [12]. If significant soft tissue injury (eg, ligament rupture or dislocation) is suspected, MRI should be obtained.

Cone beam computed tomography — Cone beam CT (CBCT), a technique with higher resolution, 90 percent less radiation exposure, and faster scanning time that conventional CT, is more sensitive for detecting radiocarpal fractures than plain radiographs. A meta-analysis of studies (n = 5; 439 patients) of clinically suspected radiocarpal fractures but negative plain radiographs (ie, occult fracture) reported that CBCT had high sensitivity and specificity for occult carpal fractures using MRI as a reference standard [13]. When available, CBCT may be a rapid and cost-effective imaging modality for suspected wrist fracture, especially occult fracture, but requires further study before it can be recommended in place of MRI, CT, or bone scan.

Ultrasonography — In skilled hands, ultrasound (US) is a useful adjunct for diagnosing a number of wrist injuries, including fractures of the carpal bones. Studies of US in diagnosis of occult scaphoid fractures (normal radiographs) show moderate sensitivity and high specificity. (See "Scaphoid fractures".) A prospective study of US in evaluating acute wrist injuries in the emergency department showed that US was 94 percent sensitive and 94 percent specific in identifying fractures [14]. Cortical disruption and adjacent joint effusion are diagnostic indicators. Performance of the wrist ultrasound examination is discussed in detail separately. (See "Musculoskeletal ultrasound of the wrist".)

DIFFERENTIAL DIAGNOSIS — In addition to fractures, other traumatic injuries that the wrist can sustain include:

●Sprain of the wrist capsule

●Sprain of any of the numerous inter-carpal ligaments, which may result in subluxation or dislocation of the carpal bones

●Injury of any of the numerous tendons crossing the wrist

●Contusions of superficial soft tissues

●Contusion of the bone without fracture ("bone bruise")

●Nerve injuries (radial, ulnar, median)

●Contusions and tears of the triangular fibro-cartilage complex (TFCC)

●Rupture of a pre-existing ganglion cyst

●Exacerbation of preexisting inflammatory joint disease (eg, rheumatoid arthritis)

A more thorough discussion of the how to evaluate the patient with wrist pain is provided separately. (See "Evaluation of the adult with acute wrist pain" and "Evaluation of the adult with subacute or chronic wrist pain".).

INDICATIONS FOR SURGICAL REFERRAL — The indications for surgical referral vary according to the bone involved and the nature of the injury. These issues are discussed in the individual topics devoted to specific carpal injuries. The basic indications for immediate referral remain unchanged and include any persistent vascular or neurologic deficit, open fracture, displaced fracture, fracture associated with dislocation or bony instability, and the development of any significant complication. (See "General principles of fracture management: Early and late complications".)

MANAGEMENT — The general principles of fracture management apply to carpal fractures. The following are recommended:

●Minimize further tissue injury, particularly of neural and vascular structures, by immobilizing the fracture. Because substantial soft tissue swelling may occur as a result of the fracture, initial immobilization is generally achieved by applying a removable plaster or fiberglass or moldable thermoplastic splint. The splint can later be removed to allow reduction, fixation, and casting. (See "Basic techniques for splinting of musculoskeletal injuries".)

●Apply ice to the injured area to minimize swelling. (See "General principles of acute fracture management".)

●Most patients obtain adequate pain relief from immobilization, ice, and over-the-counter analgesics, such as acetaminophen. Opioid analgesics are occasionally needed to control pain during the first three to five days. Patients requesting opioids beyond this time should be reevaluated for irritation from a poorly fitting splint or cast, a missed injury, or a fracture complication. (See "General principles of acute fracture management", section on 'Pain management' and "General principles of fracture management: Early and late complications".)

The effects of nonsteroidal antiinflammatory drugs on fracture healing remain a source of debate, but these drugs are best avoided with known or suspected acute fractures to minimize the risk of nonunion. These issues are reviewed separately. (See "Nonselective NSAIDs: Overview of adverse effects", section on 'Healing of musculoskeletal injury'.)

Rehabilitation of the wrist after immobilization for a carpal fracture is extremely important. Without quality rehabilitation, return to full function can be slow and possibly incomplete, resulting in chronic disability. Whenever possible, we recommend referral to an occupational or physical therapist with experience managing wrist injuries.

Treatment and rehabilitation of a carpal fracture generally consists of the following phases:

●Inflammatory and reparative phases – These occur while the fracture is immobilized, as outlined above.

●Transition-to-maturation phase – After immobilization the wrist is stiff and sore. Treatments such as heat (soaking in hot water or paraffin wax for a few minutes) can be helpful prior to gentle passive range-of-motion exercises. These exercises are done in three planes of wrist motion: flexion-extension, ulnar-radial deviation, and pronation-supination. If needed, attention should be paid to restoring finger mobility. Several weeks may be needed to regain full wrist mobility, but marked gains are often made after one to two weeks.

●Maturation phase – Once fracture healing is complete and mobility has been regained, the patient spends approximately two to eight weeks working to restore strength to the muscles about the wrist and hand. These include wrist flexors and extensors, ulnar and radial deviators, pronators and supinators, and finger flexors and extensors. This can be accomplished using elastic resistance bands, manual resistance provided by the uninjured hand, or specially designed devices found in physical therapy clinics. Therapists can also transition the patient into activities that replicate occupational or sport-specific tasks that need to be re-mastered.

ADDITIONAL RESOURCES — Additional discussion of carpal fractures may be found in texts that address the issue from an orthopedic surgical standpoint [9,15], the primary care perspective [16], and with relation specifically to fractures in athletes [3,10,17].

ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of definitive fracture management".)

●(See "General principles of acute fracture management".)

●(See "General principles of fracture management: Early and late complications".)

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".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Fractures (The Basics)" and "Patient education: Common wrist injuries (The Basics)" and "Patient education: How to care for your cast (The Basics)" and "Patient education: How to care for your child's cast (The Basics)")

●Beyond the Basics topic (see "Patient education: Cast and splint care (Beyond the Basics)")

SUMMARY

●Carpal fractures are classified by anatomic location and fracture characteristics. The eight carpal bones are subdivided into a proximal and distal row (image 1). Each carpal bone fracture is discussed in greater detail in individual topics devoted to these injuries. (See 'Classification and clinical presentation' above and 'Clinical anatomy' above.)

●The location of pain and mechanism of injury provide clues to the site of injury. Particular mechanisms and examination findings are associated with specific fractures, which are described in the text. (See 'Mechanism of injury' above and 'Symptoms and examination findings' above.)

●Standard plain radiographs to obtain when a carpal fracture is suspected include posteroanterior and true lateral views of the wrist. Additional views are indicated depending upon the suspected site of the fracture, but the overall sensitivity of plain radiographs is poor. With skilled operators, ultrasound is a useful screening tool. If clinical suspicion persists despite negative initial radiographs, the wrist can be splinted and repeat radiographs obtained in 7 to 10 days, or advanced imaging studies (eg, CT or MRI) can be performed. (See 'Imaging' above.)

●Initial treatment consists of immobilization, ice, and analgesia. Once the fracture is healed, proper physical therapy is essential in order to regain mobility and strength. (See 'Management' above.)