Metacarpal Fracture and Dislocation

Updated: Sep 07, 2018
Author: David R Steinberg, MD; Chief Editor: Craig C Young, MD 

Overview

Background

For as much as we use our hands, it is surprising that they are not injured more frequently. Sports-related metacarpal fractures most commonly occur during participation in contact sports, such as football, rugby, or basketball, in which the hands are unprotected. A direct fall onto the hand (FOOSH injury) while cycling, running, or skiing may also result in a fracture.

See the images below.

Displaced fourth and fifth metacarpal fractures, a Displaced fourth and fifth metacarpal fractures, anteroposterior view.
Displaced fourth and fifth metacarpal fractures, l Displaced fourth and fifth metacarpal fractures, lateral view.
Fourth and fifth metacarpal fractures, oblique vie Fourth and fifth metacarpal fractures, oblique view.

For patient education resources, see the Fractures and Broken Bones Center, as well as Boxer's Fracture, Broken Hand, Cast Care, Finger Dislocation, Finger Injuries, and Human Bites.

Related Medscape Reference topics:

Fracture, Hand

Hand, Fracture and Dislocations: Metacarpal [in the Plastic Surgery section]

Hand, Fracture and Dislocations: Phalangeal

Metacarpal Fractures [in the Orthopedic Surgery section]

Related Medscape topics:

Resource CenterAdolescent Medicine

Resource CenterExercise and Sports Medicine

Specialty SiteOrthopaedics

Conservative Treatment for Closed Fifth (Small Finger) Metacarpal Neck Fractures

Until the early 20th century, metacarpal fractures were treated exclusively by nonoperative means. Surgery was first suggested as an alternative treatment for certain fracture patterns in the 1920s.[1, 2]

Epidemiology

Frequency

United States

Metacarpal and phalangeal fractures are the most common fractures of the upper extremity. They account for approximately 10% of all orthopedic fractures.[2, 3] Most occur in young adults, usually as a result of direct blunt trauma, axial loading, or throwing a punch during an altercation. The thumb and small finger are the most frequently injured.

Functional Anatomy

The finger metacarpals describe a gentle arch in both the axial and coronal planes. Each bone is relatively straight along its dorsal cortex and concave along the palmar surface.

The carpometacarpal (CMC) joints consist of 5 metacarpal bases that articulate with the trapezoid, trapezium, capitate, and hamate. Articular congruity of the joint surfaces, in combination with the strong interosseous and extrinsic palmar and dorsal ligaments, provides stability to the CMC joint. The CMC joints of the index and long fingers are essentially fixed, whereas those of the ring and small fingers enjoy 20-30° of motion in flexion-extension. The thumb is extremely mobile at the CMC joint.

The opposing saddle shapes of the metacarpal base and the articulating trapezium allow for flexion, extension, abduction, and adduction. The joint capsule and ligaments permit a small degree of rotation. The most important soft-tissue support for the first CMC joint is the anterior oblique ligament, which runs from the tubercle of the trapezium to the volar beak of the metacarpal. This ligament may be ruptured in a dislocation, but it is most commonly avulsed by a fragment of bone from the ulnar corner of the metacarpal (Bennett fracture).[4]

Sport-Specific Biomechanics

The anatomic relationships described above maintain proper rotational alignment of the fingers and allow for the smooth production of power grip and the ability to clench the fist, functions that are required in many sports. The high mobility of the thumb enables both pinching (squeezing small equipment or objects between the thumb and the forefinger) and grasping of large objects.

Bennett fractures are unstable because of the deforming forces of the intrinsic and extrinsic muscles. The anterior oblique ligament stabilizes the volar-ulnar fragment, but the thenar muscles and abductor pollicis longus displace the remaining metacarpal in the proximal, dorsal, and radial directions.[5]

An analogous situation exists with the reverse Bennett fracture of the small-finger metacarpal. Intermetacarpal ligaments stabilize the radial fragment. The hypothenar and the flexor and extensor carpi ulnaris muscles pull the remaining metacarpal proximally and dorsally.

 

Presentation

History

See the list below:

  • The patient with a metacarpal fracture or CMC dislocation presents with dorsal hand pain and swelling.

  • Patients may report having limited motion in their fingers because of pain and/or deformity.

  • Paresthesias are rare, unless they are associated with severe soft-tissue injury, as is seen with multiple metacarpal fractures or with high-energy crushing injuries.

Physical

See the list below:

  • Physical examination in a patient with suspected metacarpal fracture and/or dislocation may reveal diffuse swelling and ecchymosis of the entire dorsal aspect of the hand, or findings may be limited over the involved bone.

  • Tenderness and crepitus can be palpated at the fracture site.

  • The prominence of the metacarpal head is decreased, with apex dorsal angulation of the fracture due to the pull of the intrinsic muscles.

  • Look for a possible malrotation, which is easily missed on radiographs.

  • The nails should be coplanar when the fingers are in extension, and all fingers should point toward the scaphoid tubercle in flexion.

  • Finger crossover (scissoring) during flexion indicates a malrotation.

  • As with any evaluation of the upper extremity, the neurovascular status should be documented.

  • The skin should be evaluated for lacerations or puncture wounds, which suggest an open fracture.

Related Medscape topics:

Resource CenterVascular Surgery

Specialty SiteNeurology & Neurosurgery

Causes

See the list below:

  • A sudden, forceful axial load or direct trauma can lead to transverse fractures of the metacarpal neck or shaft, as well as CMC fracture-dislocations.

  • Torsional forces may produce spiral or oblique fractures of shaft. These injuries are most likely to be associated with a rotational deformity.[6]

  • A clenched-fist injury is commonly associated with metacarpal neck fractures ("boxer fractures").[7] The usual mechanism is punching a wall or an assailant (often in the mouth).

  • High-energy crush injuries (which are rarely seen in sporting activities) lead to associated soft-tissue damage and often involve multiple metacarpal fractures.

 

DDx

 

Workup

Imaging Studies

Radiography

Standard views for all hand injuries are those obtained in the posteroanterior (PA), lateral, and oblique planes.

Acquisition of images in the Brewerton view may be indicated to evaluate the patient for CMC dislocations or for suspected avulsion of the collateral ligament.[8] To obtain Brewerton images, anteroposterior (AP) imaging is performed with the MCPJ flexed 65°, with the tube angled 15° from the radial aspect to the ulnar aspect.

The Bora view, a special oblique view of the hand, is useful for assessing suspected fracture-dislocations of the fourth or fifth CMC joint, which are difficult to delineate on standard PA radiographs. This view is obtained with AP imaging of the hand with the forearm pronated 30° from full supination. With CMC injuries, a standard oblique view should also be included in a trauma imaging series of the hand.

Computed tomography (CT) scanning

CT scanning may be indicated for investigating intra-articular fractures of the metacarpal head or the metacarpal at the base of thumb in association with multiple fragments (Rolando fracture).

CT scans may also aid in evaluating CMC fracture-dislocations, injuries to the central digits, and injury to the fifth digit (reverse Bennett fracture).

With subtle injuries of the CMC joints, CT scanning may be required to aid the clinician in determining the diagnosis and in making management decisions.

 

Treatment

Acute Phase

Rehabilitation Program

Physical Therapy

In the acute phase, minimally displaced or angulated fractures of the index finger through the small fingers should be immobilized in a forearm-based splint or cast for 3-4 weeks. The metacarpophalangeal joint (MCPJ) is flexed at 60-70°, and the proximal interphalangeal joint (PIPJ) is in the resting position (0-15°).

Injuries to which these principles apply include fractures and/or dislocations of the structures, as listed below, with their angulations.

  • Metacarpal head

  • Metacarpal neck (The exact amount of acceptable angulation may be controversial.)

    • Index and/or long finger (< 10-15°)

    • Ring finger (< 30°)

    • Small finger (< 40-50°)

  • Metacarpal shaft (The exact amount of acceptable angulation may be controversial.)

    • Index and/or long finger (< 10°)

    • Ring finger (< 20°)

    • Small finger (< 30°)

Minimally displaced or angulated extra-articular fractures of the thumb metacarpal (< 30°) can be immobilized in a forearm-based thumb spica cast for approximately 4 weeks. The IPJ is free, and the MCPJ is in 0-10° degrees of flexion. A satisfactory outcome can be expected, even with angulation up to 30°. A thumb metacarpal fracture angulated >30° may require surgical intervention. This fracture differs from intra-articular fractures of the thumb metacarpal (Bennett fracture or Rolando fracture), most of which require surgical stabilization.[9, 10]

CMC fracture-dislocations require the application of a forearm-based cast, usually for 6 weeks. Direct pressure can be applied dorsally to the metacarpal base to reduce the CMC joint.

Radiographs should be obtained immediately after the cast is applied and weekly for the first 3 weeks to ensure that the reduction of these usually unstable injuries is maintained.

Occupational Therapy

Gentle active range of motion (ROM) of the uninvolved digits, as well as the shoulder and elbow, should be encouraged. The physician, trainer, or therapist can instruct the patient to perform these exercises on a daily basis at home. Formal therapy is usually unnecessary at this point.

Minimally displaced avulsion injuries of the collateral ligament in the MCPJ can be treated with early buddy taping to the adjacent uninjured finger for 3 weeks. A hand-based splint may provide additional protection at nighttime during sleep.

Medical Issues/Complications

Malrotation, if present, must be corrected. This condition remains a clinical diagnosis because radiographs often inadequately demonstrate rotational deformities. In extension, the fingernails should be within 10° of alignment. Scissoring (crossover) of the digits should be absent during simultaneous finger flexion. Make sure to examine both hands, as some individuals have a normal degree of small-finger overlap with the ring finger in flexion.

Penetrating injuries caused by a tooth (see Human Bites) are often encountered in association with fractures of the metacarpal neck and head that are sustained during an altercation. Maintain a high level of suspicion, carefully obtain the patient's history, and closely look for a small, dorsal laceration over the MCPJ. If penetrating injuries are not diagnosed and treated early with irrigation and debridement, the incidence of infection is high (see Human Bite Infections). This is particularly true of penetrating injuries into the joint, which require surgical arthrotomy to prevent septic arthritis. These injuries are also associated with extensor tendon injuries.

CMC dislocations can easily be missed. As subluxations, in particular, they may be difficult to diagnose. Have a high level of suspicion when a patient presents with dorsal tenderness and swelling of the proximal portion of the hand. An isolated fracture of the ring metacarpal should suggest a possible concomitant injury to the fifth CMC joint.[11] The dorsal prominence of the metacarpal base may be palpable. Lateral and oblique radiographs must be examined closely. Strongly consider CT scanning if the radiographic findings are inconclusive.

With an isolated metacarpal fracture, a border digit obtains intact skeletal and ligamentous support from only 1 neighboring metacarpal, a situation that renders it more unstable than a central digit. In addition, a transverse fracture is more unstable and vulnerable to malrotation than is an oblique fracture, which has an increased area of bony contact and an increased likelihood of fragment interdigitation.

Surgical Intervention

Surgical intervention is indicated to treat the following injuries:

  • Fractures of the metacarpal shaft and neck with unacceptable amounts of angulation or malrotation

  • Unstable injuries

    • Most CMC dislocations

    • Intra-articular fractures of the thumb metacarpal base (Bennett fracture, Rolando fracture)

    • Fracture of the fifth metacarpal base (reverse Bennett fracture)

  • Fractures associated with human bites (involvement of the MCPJ)

  • Metacarpal head fractures with a clinically significant articular step-off

A variety of surgical approaches are available. The choice of procedure depends on the nature of the fracture and the preference or experience of the surgeon. Fixation techniques described in the literature include these:

  • Open reduction and internal fixation (ORIF) to treat a displaced metacarpal head

  • Closed treatment or traction to manage a comminuted metacarpal head

  • Closed reduction and percutaneous pinning to treat an injury of the metacarpal neck

  • Closed reduction and percutaneous pinning and/or intramedullary fixation versus ORIF to manage an injury to the metacarpal shaft

Intra-articular fractures of the thumb metacarpal base usually require surgical intervention, namely, reduction and percutaneous pinning for a Bennett fracture, and pinning or ORIF for a Rolando fracture. Closed reduction is achieved with a combination of traction, extension, pronation, and direct application pressure on dorsum of the metacarpal base. Comminuted fractures may require external fixation or oblique traction through the thumb metacarpal. A study by Pomares et al reported success with arthroscopically assisted percutaneous screw fixation for intra-articular fractures.[12]

 

CMC dislocations or fracture-dislocations are poorly maintained in a splint or cast. Isolated injuries, particularly those involving the small finger, frequently require closed reduction and percutaneous pinning.[13] Multiple CMC dislocations often require open reduction. Mini external fixators are useful in severely comminuted CMC fractures. To minimize posttraumatic arthritis, pay attention to the articular step-offs of the relatively mobile ring and small fingers.

Potentially contaminated open fractures require irrigation and debridement to prevent osteomyelitis or an infected nonunion. A fight bite, in which an apparently clean laceration is most likely caused by an assailant’s tooth indicates that penetration of the MCPJ is likely. If this injury is suspected, arthrotomy and irrigation of the MCPJ is indicated to prevent septic arthritis. If elevated compartment pressures are suspected on the basis of clinical findings or measured intracompartmental pressures, urgent fasciotomy is indicated.

A retrospective study compared clinical and radiographic outcomes between intramedullary nail fixation and percutaneous K-wire fixation for fractures in the distal third portion of the metacarpal bone. The study concluded that intramedullary nailing fixation is advisable for these fractures. The authors advise that intramedullary nailing fixation provides early recovery of the range of motion, an earlier return to work, and lower complication rates.[14]

Related Medscape Reference topics:

Compartment Pressure Measurement

Compartment Syndromes

Compartment Syndrome, Upper Extremity

Consultations

A hand surgeon or an orthopedic surgeon should be consulted if the patient has any injury that requires surgery or if the diagnosis is unclear. Immediate consultation is indicated when the injuries are open or irreducible or when neurovascular compromise of the digit is present. After closed reduction is successfully accomplished, arrange for follow-up within 1 week with an orthopedic surgeon or hand surgeon.

Recovery Phase

Rehabilitation Program

Occupational Therapy

The program of occupational therapy following a metacarpal fracture and/or dislocation should be supervised and should include the following elements:

  • Progressive range of motion

    • Active

    • Active assisted

    • Gentle passive

  • Strengthening exercises

  • Management of edema

  • Thermal modalities

Medical Issues/Complications

See the list below:

  • During the recovery phase, stiffness and weakness are the most clinically significant problems encountered.

  • Persistent or previously unrecognized malrotation may also become evident as digital motion increases.

Surgical Intervention

Therapy is usually effective in overcoming stiffness after metacarpal fractures and dislocations occur. If clinically significant functional problems persist after a minimum of 3 months, surgical intervention can be considered. Surgery can be delayed for an additional 3 months if the patient desires it, because continued improvement with therapy can be seen as long as 6 months after the injury.

Surgery to manage persistent adhesions and/or contractures usually consists of extensor tenolysis and dorsal MCPJ capsulotomy. This is immediately followed by an aggressive program of hand therapy.

Consultations

A hand surgeon should be consulted for any problem that is not responding appropriately to a supervised therapy program.

 

Medication

Medication Summary

The goals of pharmacotherapy in patients with metacarpal fractures and/or dislocations are to reduce morbidity and prevent complications.

Analgesics

Class Summary

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and enables physical therapy regimens. Many analgesics have sedating properties, which are beneficial for patients that have sustained injuries.

Related Medscape Reference topic:

Toxicity, Acetaminophen

Related Medscape topics:

Resource CenterAdverse Drug Events Reporting

Resource CenterPain Management: Advanced Approaches to Chronic Pain Management

Resource CenterPain Management: Pharmacologic Approaches

Acetaminophen and codeine (Tylenol with Codeine)

Combines the analgesic effects of centrally acting opium-derived alkaloid (codeine) and peripherally acting nonopioid analgesic (acetaminophen). Indicated for the treatment of mild to moderate pain.

Acetaminophen (Aspirin Free Anacin, Feverall, Tempra, Tylenol)

DOC for pain in patients who have documented hypersensitivity to aspirin or NSAIDs, who have upper GI disease, or who are taking oral anticoagulants.

Effective in relieving mild to moderate acute pain but has no peripheral anti-inflammatory effects. May be preferred in elderly patients because of reduced GI and renal adverse effects.

 

Follow-up

Return to Play

The patient recovering from a metacarpal fracture and/or dislocation may be able to return to nonstrenuous activities at 6-8 weeks. Unprotected participation in contact sports should be avoided for 3 months.

Complications

See the list below:

  • Painful or prominent hardware may need to be removed after the metacarpal fracture has fully healed.

  • Angular or rotational malunions that substantially affect hand function may be treated with osteotomy.

  • Nonunions are rare. Patients who desire to avoid surgery can try using external bone-growth stimulators. Definitive treatment usually consists of surgical take-down of the nonunion, followed by stabilization and bone grafting.

  • Posttraumatic arthritis may occur after any intra-articular injury.

    • Conservative treatment consists of joint protection, activity modification, and judicious use of corticosteroid injections.

    • Standard pharmacologic treatment for arthritis may also be considered.

    • Relatively severe cases may require surgery, including osteotomy, arthroplasty, or arthrodesis.

Prevention

Hand injuries are difficult to completely prevent in active individuals, particularly those involved in high-risk contact sports. Buddy-taping of previously injured fingers may help prevent further fractures and dislocations.

Prognosis

After an appropriate period for healing and rehabilitation, most patients regain relatively normal use of the hand. Some residual stiffness or weakness is not entirely unusual.