Metacarpal head fractures

INTRODUCTION — Metacarpal fractures are common injuries [1]. They account for 30 to 40 percent of all hand fractures. This topic will review issues related to metacarpal head fractures, which are usually the result of direct trauma.

Fractures of the metacarpal head are reviewed here. Other types of metacarpal fractures and a general overview are presented separately. (See "Overview of metacarpal fractures" and "First (thumb) metacarpal fractures" and "Metacarpal shaft fractures" and "Metacarpal base fractures" and "Metacarpal neck fractures".)

CLINICAL ANATOMY — General anatomy of the metacarpals is reviewed separately; anatomy of particular relevance to fractures of the metacarpal head are described here. (See "Overview of metacarpal fractures", section on 'Anatomy'.)

Metacarpal heads articulate with their corresponding phalanx. Thus, a fracture of the head is, by definition, an intraarticular fracture. The heads of the metacarpals are bulbous and "cam" shaped, thereby permitting adduction, abduction, flexion, extension and passive rotation of the fingers. The collateral ligaments join the metacarpal to the proximal phalanx and are taut in flexion, while having some laxity in extension (figure 1). The second metacarpal serves as a "border metacarpal" for the hand and is fixed at its base to the distal carpal row, making it the metacarpal head most susceptible to injury [1,2].

MECHANISM OF INJURY — Fractures of the metacarpal heads are relatively uncommon and usually result from a direct blow, crush injury, or projectile. During an altercation, a metacarpal head fracture may be sustained when the patient strikes someone or something with a closed fist. The second metacarpal head (ray of index finger) is most commonly involved, and the first metacarpal head (ray of thumb) is rarely fractured. In some patients, rupture of the collateral ligaments through a torsional, valgus, or varus stress can result in avulsion fractures at the metacarpal head. First metacarpal fractures are discussed separately. (See "First (thumb) metacarpal fractures".)

CLINICAL PRESENTATION AND EXAMINATION — Patients who have sustained a metacarpal head fracture typically present complaining of pain and swelling at the distal aspect of the metacarpal following trauma. Prominent swelling, decreased range of motion at the metacarpophalangeal (MCP) joint, focal tenderness over the distal metacarpal, along with occasional palpable defect or crepitus in some cases, are noted on examination. Axial loading of the MCP joint worsens pain.

If significant pain or laxity is noted during valgus or varus stress of the MCP joint, collateral ligament injury or an avulsion fracture may have occurred. During the examination, it is important to assess for rotational deformity and any skin lesion suggesting an open fracture.

Rotational alignment — Even small rotational deformities can produce significant disability. Rotational alignment should be carefully assessed with the MCP joint in flexion. The rotational alignment of the metacarpals can be assessed in two ways:

●With a semi-clenched fist (flexion to 90 degrees at the MCP and proximal interphalangeal [PIP] joints), normal alignment will enable each finger to point toward the scaphoid pole and show convergence of the digits but not necessarily to a single point (picture 1A-B).

●With the MCP joint flexed 90 degrees and the PIP and distal interphalangeal [DIP] joints in full extension, the plane of the fingernails should be aligned and can be compared with the contralateral side (picture 2).

Skin integrity — Special attention must be paid to skin integrity near the metacarpal head since this site is particularly prone to injury caused by a tooth during an altercation and are accordingly known as "fight bites." Any evidence of laceration or skin breakdown requires aggressive decontamination to avoid potentially disastrous intraarticular infections. Prophylactic antibiotics appear to be beneficial with hand bites. (See "Human bites: Evaluation and management".)

DIAGNOSTIC IMAGING — A standard hand series (anteroposterior [AP], lateral, and oblique views) should be ordered if a metacarpal head fracture is suspected. In addition, for skilled practitioners, point-of-care ultrasonography provides an accurate and rapid method for establishing a preliminary diagnosis of metacarpal fracture. An observational study of 66 patients presenting to the emergency department with suspected metacarpal fracture reported a sensitivity of 92 percent and specificity of 87 percent using plain radiographs as the gold standard [3]. While ultrasound can be helpful for initial diagnosis, it may not provide adequate fracture detail [4].

If neither plain films nor ultrasound reveal abnormalities of the metacarpal heads, but the clinician suspects an occult fracture or other bony injury based on mechanism and clinical examination, a non-contrast computed tomography [CT] is the imaging study of choice to define this injury. Magnetic resonance imaging [MRI] is helpful for the evaluation of soft-tissue injuries, but CT is superior for the evaluation of bony anatomy.  

Of note, metacarpal head fractures often are significantly comminuted (image 1) and may occur in conjunction with metacarpal neck fractures. (See "Metacarpal neck fractures".)

If a collateral ligament avulsion fracture is suspected (eg, laxity identified with varus or valgus stress of MCP joint) but not visualized on standard views, a Brewerton view (metacarpophalangeal [MCP] joint flexed at 65 degrees with the proximal phalanx flat on the cassette and the beam directed 15 degrees ulnar) can be helpful.  

DIAGNOSIS — Fractures of the metacarpal head are diagnosed by diagnostic imaging, typically plain radiograph, but possibly CT. Ultrasound may serve as a useful screening tool. Clinicians should suspect such injuries in patients who have sustained direct trauma to the area around the metacarpal head, and manifest pain, swelling, and focal tenderness at the site.

DIFFERENTIAL DIAGNOSIS

Metacarpophalangeal dislocation/subluxation — Metacarpophalangeal (MCP) joint dislocation or subluxation typically presents with an acutely painful and swollen MCP joint following trauma and can mimic the presentation of an MCP fracture. However, dislocations typically manifest more prominent deformity, and patients are unable to flex and extend at the MCP joint. Dislocations most commonly involve the second MCP joint, are dorsal, and caused by a hyperextension injury. Radiographs clearly distinguish between fracture and dislocation; the lateral view is best for identifying dislocation.

Acute gout — Although uncommon, isolated gouty flares of the MCP joint present with swelling, redness, and exquisite pain, made markedly worse with range of motion testing of the joint. The key to distinguishing between acute gout and fracture is the presence or absence of trauma. Gout flares arise in the absence of trauma; metacarpal head fractures are caused by trauma and are apparent on radiograph. (See "Clinical manifestations and diagnosis of gout" and "Treatment of gout flares".)

Acute synovitis — The swelling, pain, redness, and painful motion caused by non-gouty synovitis can mimic a metacarpal head fracture. The presence or absence of trauma is the key to distinguishing between the two conditions. Non-gout synovitis is more common in patients with underlying rheumatologic condition. Metacarpal head fractures are caused by trauma and are apparent on radiograph.  

INDICATIONS FOR SURGICAL REFERRAL — Immediate surgical consultation is required for all open fractures and for all fractures with associated vascular compromise or nerve injury. Associated neurovascular injury is uncommon with isolated metacarpal head fractures. In addition, early referral is needed for patients with a metacarpal head fracture associated with a complete tendon laceration. It is best to discuss the case directly with the hand surgeon who will assume care to determine the timing for follow up. (See "General principles of fracture management: Early and late complications".)

Most metacarpal head fractures require referral because they are intraarticular and typically comminuted [5,6]. If the fragments are small and multiple, nonoperative management may be considered, but consultation should be sought before pursuing this approach. Any rotational deformity requires correction. (See 'Rotational alignment' above.)

Small avulsion fractures caused by collateral ligament injuries can be treated nonoperatively if the fragment is small and displaced no more than 3 mm. These injuries can be treated appropriately using the measures outlined below.

INITIAL TREATMENT — The following discussion describes the initial therapeutic approach in patients who do not require immediate fracture reduction or orthopedic referral as described above. Basic initial treatment for fractures is reviewed separately. (See 'Indications for surgical referral' above and "General principles of acute fracture management".)

Splinting is used in the initial immobilization of, and sometimes is the definitive treatment for, metacarpal fractures [1,7]. A detailed description of the techniques for applying splints is presented separately. (See "Basic techniques for splinting of musculoskeletal injuries" and "Patient education: Cast and splint care (Beyond the Basics)".)

Acute management of metacarpal head fractures involves use of an ulnar (picture 3 and figure 2) or radial gutter splint (metacarpophalangeal [MCP] joints in 50 to 60 degrees of flexion; wrist in approximately 10 to 20 degrees extension; proximal and distal interphalangeal joints in full extension) or a bulky hand dressing in a position of function. Ulnar gutter splints are used for fourth and fifth metacarpal head fractures, while radial gutter splints are used for injuries to the second and third metacarpals. Icing and elevation are employed during the first 48 to 72 hours to minimize swelling. Metacarpal head fractures should be reassessed within one week. (See "Overview of finger, hand, and wrist fractures", section on 'Splint placement and position'.)

FOLLOW-UP CARE — Non-displaced metacarpal head fractures typically are immobilized for two to three weeks using a gutter splint prior to initiation of range of motion exercises [7]. Prolonged immobilization is avoided in order to prevent chronic stiffness, which is the most common complication of non-displaced metacarpal head fractures. Repeat radiographs should be performed at one week and at the time immobilization is completed (two to three weeks). If fragments displace at any time, orthopedic referral is indicated.

While joint stiffness due to scarring of the ligamentous structures is a common complication, avascular necrosis (AVN) is the most significant morbidity associated with fractures of the metacarpal head. AVN occurs more often in displaced or horizontal fractures. We suggest obtaining radiographs one year following injury or if the patient is experiencing any suggestive symptoms to rule out AVN [8]. (See "Treatment of nontraumatic hip osteonecrosis (avascular necrosis of the femoral head) in adults".)

RETURN TO SPORT OR WORK — Return to active use depends upon the type of activity in which the patient will engage. Advice differs for returning to sports and work.

●Athletes should have full, pain-free range of motion and radiographic evidence of healing prior to return to sports. It is important to inform athletes that discontinuation of splinting at two to three weeks to allow range of motion does not mean that the fracture has completely healed. When evidence of bony healing is apparent, athletes can return to play but should wear protective padding or an orthosis for four to six weeks after the initial period of immobilization is complete. They can expect to be out of competition for four to six weeks.

●Patients requiring regular use of the fractured hand at work can return to full duty when they have functional range of motion, are pain-free, and non-tender.

PEDIATRIC CONSIDERATIONS — Pediatric metacarpal head fractures are uncommon and typically caused by axial load, often with a rotational component [2]. As with adults, close attention must be paid to rotational alignment, particularly with "border" digits (ie, second and fifth metacarpal heads). (See 'Rotational alignment' above.)

The collateral ligaments at the MCP joint originate and insert on the epiphysis, leaving the growth plate of skeletally immature patients vulnerable to injury. Metacarpal head fractures involving the collateral ligaments are typically Salter Harris Type II fractures and these sometimes occur in teenagers. Epiphyseal and physeal fractures of the second and third metacarpal heads are uncommon.  

Joint effusion is an important consideration in skeletally immature patients with a metacarpal head fracture. An effusion can constrict the blood vessels that supply the epiphysis, ultimately leading to avascular necrosis (AVN), which is characterized by exquisite pain. Any metacarpal fracture associated with severe pain and an effusion in this population should be referred immediately to an orthopedic surgeon. As with adults, malaligned, displaced, and comminuted fractures should also be referred promptly. Nondisplaced avulsion fractures and minimally displaced Salter Harris Type II fractures may be treated conservatively with a radial or ulnar gutter splint, typically for two to three weeks, as in adults. (See 'Indications for surgical referral' above and "Treatment of nontraumatic hip osteonecrosis (avascular necrosis of the femoral head) in adults".)

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".)

SUMMARY AND RECOMMENDATIONS

●Mechanism of injury – Metacarpal head fractures are typically intraarticular fractures that occur from crush injury or a direct blow. Avulsion fractures involving the metacarpal head result from torsional, varus, or valgus stress at the metacarpophalangeal (MCP) joint. (See 'Mechanism of injury' above.)

●Clinical presentation and examination – Patients with a metacarpal head fracture typically complain of pain and swelling at the distal aspect of the metacarpal following trauma. Prominent swelling, decreased range of motion at the MCP joint, and focal tenderness over the distal metacarpal are common findings. Examination should include assessment of rotational alignment and skin integrity. (See 'Clinical presentation and examination' above.)

●Imaging and diagnosis – A standard hand series of plain radiographs (anteroposterior [AP], lateral, and oblique views) is sufficient to diagnose a metacarpal head fracture in the large majority of cases, and to distinguish it from common alternative diagnoses. Ultrasound may serve as a useful screening tool. (See 'Diagnostic imaging' above and 'Differential diagnosis' above.)

●Need for surgical referral – Metacarpal head fractures are often displaced, comminuted, and/or intra-articular and accordingly warrant orthopedic or hand surgery referral. They typically are not managed by primary care clinicians. (See 'Indications for surgical referral' above.)

●Minor avulsion fractures – Small avulsion fractures caused by collateral ligament injuries can be treated nonoperatively if the fragment is small and displaced no more than 3 mm. (See 'Initial treatment' above and 'Follow-up care' above.)

●Minor non-displaced fractures – Small, non-displaced fractures can be splinted for two to three weeks, followed by rapid initiation of range of motion exercises to prevent stiffness.

●Management of wounds from human teeth – Puncture wounds or lacerations due to human teeth ("fight bites") warrant aggressive treatment to prevent serious intraarticular infection. (See "Human bites: Evaluation and management", section on 'Evaluation'.)

●Avascular necrosis – Avascular necrosis (AVN) is the most significant morbidity associated with fractures of the metacarpal head. AVN occurs more often in displaced or horizontal fractures. We suggest obtaining plain radiographs at one year or if the patient is symptomatic during follow up to evaluate for AVN. (See 'Follow-up care' above.)