Metacarpal Fractures




Fractures of the metacarpals are the second most common type of fracture seen in a primary care setting. They are classified according to the anatomic location of the fracture: head, neck, shaft, and base. The neck and shaft are the most common fracture sites for the second through fifth metacarpals. Most first metacarpal fractures occur at the base. The treatment of fractures involving the first metacarpal differs from that involving fractures of the second through fifth metacarpals, because the biomechanics of the thumb are distinct from those of the other fingers. Management of fractures of the first metacarpal is discussed separately.


See Appendix for stepwise instructions for gutter and thumb spica splints and short arm casts used in the treatment of metacarpal fractures.


Go to Expert Consult for the electronic version of a patient instruction sheet named “Broken Hand or Wrist,” which covers the steps of care from pain relief to rehabilitation exercises. This can be copied to hand out to patients to assist them during the treatment period.


Metacarpal Head


Anatomic Considerations


The head of the metacarpal is cam shaped; that is, the radius of the pivot point from the metacarpal to the phalanx is greater in flexion than in extension. This allows the collateral ligaments joining the metacarpal to the proximal phalanx to be relaxed in extension, permitting slight lateral motion, and to become taut in flexion ( Fig. 4-1 ). If the metacarpophalangeal (MCP) joint is immobilized in extension, the collateral ligaments shorten, and the MCP joint becomes stiff. The metacarpal heads are weakly joined by the distal transmetacarpal ligament.




FIGURE 4-1


The collateral ligaments of the metacarpophalangeal joint are relaxed in extension but become taut in full flexion.


Mechanism of Injury


Fractures of the metacarpal head are usually caused by crush injuries or direct blows. The second metacarpal is the most likely to be injured, presumably because of its position as a “border metacarpal” and the fact that its base is fixed to the distal carpal row. Fractures of the first metacarpal head are rare.


Clinical Presentation


During examination, the MCP appears tender and swollen with poor range of motion (ROM), and pain is exacerbated by axial compression of the affected digit. The patient should be examined for any rotational deformity. Careful inspection of the soft tissue over the MCP joint is necessary to detect whether contact with a tooth has caused a small laceration. These lacerations can lead to serious infection if not treated with aggressive wound exploration and cleansing.


Imaging


A standard three-view hand series (anteroposterior [AP], lateral, and oblique) is usually adequate to diagnose a fracture of the metacarpal head. Occasionally, a 10-degree pronated or supinated lateral view is helpful. All metacarpal head fractures are intraarticular. Most are comminuted, and only infrequently is a two-part fracture observed. Fractures of the head are often combined with neck fractures ( Fig. 4-2 ). Collateral ligament avulsion fractures may also be seen.




FIGURE 4-2


A, Anteroposterior view. B, Oblique view of the hand demonstrating a fracture of the fifth metacarpal head and neck ( arrows ).


Indications for Orthopedic Referral


Patients with displaced and comminuted metacarpal head fractures should be referred to an orthopedist for surgical fixation. If the comminution is severe, the patient may do just as well with splint immobilization followed by early active motion, but the consultant should decide between surgical and conservative treatment.


Initial Treatment


Table 4-1 summarizes the management guidelines for metacarpal head fractures. The acute management of these fractures should include ice, elevation, analgesics, and immobilization in a radial or ulnar gutter splint ( see Appendix for a stepwise description of how to apply a gutter splint) or a soft bulky hand dressing with the hand in a position of function. A position of function is with the wrist in 20 to 30 degrees of extension and the fingers and thumb in a slightly flexed position. The hand should be immobilized until the patient is seen by the orthopedist or returns for a follow-up visit in 1 week.



Table 4-1

Management Guidelines for Metacarpal Head Fracture







































initial treatment
Splint type and position Gutter splint: wrist, 30 degrees of extension; metacarpophalangeal, 70 to 90 degrees; proximal interphalangeal or DIP, 5 to 10 degrees; or bulky hand dressing
Initial follow-up visit 1 week
Patient instruction Icing, elevation of hand above level of heart
follow up care
Cast or splint type and position Gutter splint
Length of immobilization 2 to 3 weeks
Healing time 4 to 6 weeks
Follow-up visit interval Every 2 weeks
Repeat radiography interval


  • 1 week after injury to check for alignment



  • At completion of immobilization to document healing

Patient instruction Begin active ROM exercises after immobilization
Indications for orthopedic consult


  • Displaced fractures



  • Comminuted fracture


DIP, distal interphalangeal; ROM, range of motion.


Follow-up Care


Nondisplaced fractures of the metacarpal head should be treated with a gutter splint for approximately 2 weeks (prolonged immobilization should be avoided). Repeat radiographs should be obtained within a week of injury to ensure that the fragments are not displaced, and active ROM exercises should be started after immobilization. Patients with displacement at any time during the healing process should be referred to an orthopedic surgeon.


Complications


Chronic stiffness caused by tendon adhesions, collateral ligament shortening, or dorsal capsular contracture is the most common complication of these intraarticular fractures. Comminuted metacarpal head fractures may result in moderate to severe loss of ROM. Avascular necrosis can occur, especially after occult compression fractures from decreased blood flow to the fracture site.


Return to Work or Sports


Fractures of the metacarpal head are difficult to treat, and rehabilitation efforts must be closely monitored to promote full ROM. The patient should begin ROM exercises at the MCP joint as early as possible, initially under the direct supervision of an experienced physical therapist or hand therapist. Early motion helps mold fracture fragments into an acceptable articular surface. Rehabilitation can then be advanced to help patients regain fine hand movements and functional grip strength. Patients may be ready to resume work 6 to 8 weeks after injury, but treatment must be individualized.


Pediatric Considerations


Epiphyseal and physeal fractures of the fifth metacarpal head are not uncommon, especially among patients 12 to 16 years of age. When these injuries occur, they are most usually Salter-Harris type II fractures ( Fig. 4-3 ); epiphyseal and physeal fractures of the second and third metacarpal heads rarely occur. Anatomic considerations are particularly important for injuries to the metacarpal head in this age group. The collateral ligaments at the MCP joint originate and insert almost exclusively on the epiphysis. The growth plate is thus relatively unprotected from injury, and a tense effusion can occur after fracture of the metacarpal epiphysis. This pressure can tamponade the vessels supplying the epiphysis, leading to necrosis and growth arrest.




FIGURE 4-3


Salter-Harris type II fracture of metacarpal head ( arrow ).

(From Thornton A, Gyll C. Children’s Fractures: A Radiological Guide to Safe Practice . Philadelphia, WB Saunders, 1999.)


The typical mechanism of injury is an axial load to the finger, usually accompanied by some rotational component. The dorsum of the child’s hand should be examined carefully for significant swelling, which may not be immediately apparent. During physical examination, the patient’s finger should be evaluated for malalignment because the “border digits” (i.e., the second and fifth metacarpals) are particularly prone to malalignment injuries. A small amount of displacement in the metacarpal head can cause significant malrotation of the distal portion of the finger.


Nondisplaced avulsion fractures caused by the collateral ligaments or minimally displaced type II fractures can be treated conservatively. The patient’s hand should be immobilized for 2 to 3 weeks in an ulnar or radial gutter splint with the wrist in slight extension, the MCP joints in full flexion, and the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints in full extension. Active ROM exercises should be started after immobilization. Splinting for nondisplaced and minimally displaced fractures yields consistently positive results.


Displaced fractures should be splinted and the patients referred promptly for definitive treatment by orthopedic surgeons.


Intraarticular head-splitting Salter-Harris type II, type III, and type IV fractures are rare. As mentioned earlier, the rich blood supply of the epiphyseal and periphyseal areas can lead to avascular necrosis caused by intracapsular bleeding. The treating physician should consider aspiration of the MCP joint effusion to reduce the risk of pressure necrosis. Reducible but unstable fractures may require pin fixation, and displaced intraarticular fractures may require open reduction and internal fixation. In such cases, the referring physician may consider joint aspiration before referral.




Metacarpal Neck


Anatomic Considerations


The dorsal and volar interosseous muscles originate from the shafts of the metacarpals and act as flexors of the MCP joints. After a metacarpal neck fracture, the action of the interosseous muscles causes volar displacement of the metacarpal head (apex dorsal angulation). Some degree of angulation (20 to 40 degrees) of the neck can be accepted in the fourth and fifth metacarpals, because compensatory motion at the carpometacarpal (CMC) joint is available. The bases of the second and third metacarpals are practically fixed at the distal carpal row with virtually no motion. Thus, no angulation is tolerated in neck fractures of the second and third metacarpals.


Mechanism of Injury


Metacarpal neck fractures usually result from a direct axial force such that is caused by punching a solid object or wall with a clenched fist. The fifth metacarpal neck fracture is by far the most common hand fracture encountered and is referred to as a boxer’s fracture.


Clinical Presentation


When a metacarpal neck fracture occurs, the dorsum of the hand is tender and swollen, sometimes quite significantly. The MCP joint is depressed because of the apex dorsal angulation of the fracture. If the angulation is severe (>40 degrees), the displaced metacarpal head may interfere with the normal function of the extensor apparatus, causing pseudoclawing. Hyperextension of the MCP joint and flexion of the PIP joint as the patient attempts to extend the finger ( Fig. 4-4 ) confirm the presence of pseudoclawing.




FIGURE 4-4


Comminution of the volar cortex in metacarpal neck fractures allows volar displacement of the metacarpal head. This may in turn disrupt the extensor mechanism, causing the so-called pseudoclawing phenomenon.


Malrotation often accompanies a metacarpal neck fracture, and the patient should be examined carefully to detect this type of displacement. Malrotation occurs more commonly in the border metacarpals (i.e., the second and fifth metacarpals). With the fingers in a semiflexed position, the plane of the fingernails should be aligned; in the fully flexed position, the fingers should all point toward the distal radius. The hand must be examined for any evidence of teeth marks that may result from a punching injury because this is a source for infection and should be treated as an open fracture.


Imaging


Three views of the hand are usually adequate to visualize a metacarpal neck fracture (AP, lateral, and oblique views). The fracture is often comminuted on the volar side. The typical apex dorsal angulation should be measured on the lateral view ( Fig. 4-5 ). The normal metacarpal neck angle is 15 degrees, so a measurement of 40 degrees of apex dorsal angulation represents true angulation of only 25 degrees.




FIGURE 4-5


A, Anteroposterior view ( arrow ). B, Lateral view of a boxer’s fracture. Forty degrees of apex dorsal angulation is observed on the lateral view.


Indications for Orthopedic Referral


Patients with angulated or displaced fractures of the second or third metacarpal neck require referral for operative treatment. Patients who have metacarpal neck fractures with rotational malalignment must also be referred. If any degree of residual angulation is unacceptable to the patient, referral for internal fixation is indicated.


Initial Treatment


Table 4-2 summarizes management guidelines for metacarpal neck fractures. The best method of treating angulated fractures of the fourth or fifth metacarpal has not been universally established. Although reduction of these fractures is relatively easy, maintaining the reduction is often difficult. Virtually all neck fractures are inherently unstable because of deforming forces of the interosseous muscles and comminution of the volar cortex. The only position of the MCP joint that adequately holds the reduction is full extension. However, the MCP joint is prone to significant stiffness if held in extension for longer than 7 to 10 days. The risk of disabling loss of joint mobility outweighs the benefits of this positioning, so it is recommended to place the MCP joints in 70 to 90 degrees of flexion.



Table 4-2

Management Guidelines for Metacarpal Neck Fracture







































initial treatment
Splint type and position Gutter splint: wrist, 30-degree extension; MCP, 70 to 90 degrees; PIP or DIP, 5 to 10 degrees
Initial follow-up visit Within 4 to 5 days for second or third metacarpal
Within 7 to 10 days for fourth or fifth metacarpal
Patient instruction Icing, elevation
follow up care
Cast or splint type and position Gutter splint
Length of immobilization 3 to 4 weeks
Healing time 4 to 6 weeks
Follow-up visit interval Every 2 weeks
Repeat radiography interval At initial follow-up to check for angulation or malrotation
Every 2 weeks to document position and healing
Patient instruction


  • Begin ROM exercises after immobilization (handgrip strengthening)



  • Avoid contact sports for 4 to 6 weeks after immobilization or use orthotic protection

Indications for orthopedic consult


  • Angulated or displaced fractures of second or third metacarpal



  • Malrotation



  • Angulation unacceptable to patient after closed reduction



  • Unable to hold reduction position



  • Malunion with painful grip or pseudoclawing


DIP, distal interphalangeal; MCP, metacarpophalangeal; PIP, proximal interphalangeal; ROM, range of motion.


Fractures requiring that the patient be referred to an orthopedic surgeon should be immobilized in a radial or ulnar gutter splint with the MCP joints in 70 to 90 degrees of flexion and the PIP and DIP joints in slight flexion until the patient is seen by the consultant.


Nondisplaced Fractures (Second or Third Metacarpal) and Fractures with Mild Angulation (Fourth or Fifth Metacarpal)


Patients with nondisplaced fractures of the second or third metacarpal or mildly angulated fractures of the fourth or fifth (<30 degrees) metacarpal can have the injured hand immobilized in a radial or ulnar gutter splint. Several alternatives to rigid splint immobilization in the treatment of metacarpal neck fractures have been proposed in small trials, including elastic bandaging, functional taping, molded bracing, and functional treatment. None of these treatments has been shown to be definitively superior to rigid splinting, but they are good alternatives to those who may not tolerate the stiffness associated with immobilization.


Fractures with Significant Angulation or Pseudoclawing (Fourth or Fifth Metacarpal)


An attempt at closed reduction is mandatory if pseudoclawing is apparent during physical examination. Patients with significant angulation (>30 degrees) but no pseudoclawing often benefit from closed reduction. However, they may also achieve good clinical healing from immobilization without reduction. Patients should be advised that residual angulation and deformity are likely despite closed reduction. The deformity is usually cosmetic and causes no functional impairment. Patients may decide against reduction if they accept these possible outcomes.


Other factors to consider in decision making regarding reduction include the amount of soft tissue padding in the palm (a petite hand may not tolerate as much residual deformity), occupational recreational demands of the hand (especially gripping or use of hand tools), and length of time from the injury to time of treatment.


Method of Reduction


Anesthesia can be administered by either a hematoma block at the site of the fracture or an ulnar nerve block at the wrist. For a hematoma block, a Betadine scrub of the skin is performed over the fracture site. The local anesthetic (5 to 8 mL of 1% lidocaine without epinephrine) is injected gradually by alternate injection, with half the volume of anesthetic injected initially. The blood from the hematoma is then withdrawn up to the original volume. The mixture of blood and lidocaine is repeatedly injected and reaspirated until the anesthetic is dispersed in the hematoma. The final aspirate should be equal to the original anesthetic volume so that the volume of fluid in the hematoma has not been increased.


A complete ulnar nerve block involves injections for both the ulnar nerve at the wrist and the dorsal sensory branch of the ulnar nerve. Performance of an ulnar nerve block begins with a sterile scrub of the skin over the ulnar side of the wrist. The provider palpates the pisiform bone, a prominence felt just beyond the distal wrist crease on the ulnar side of the wrist with the wrist in extension. Between 2 and 3 mL of 1% lidocaine without epinephrine is injected into the subcutaneous tissues just proximal to the pisiform bone between the proximal and distal creases of the wrist ( Fig. 4-6 ). The dorsal sensory branch of the ulnar nerve is anesthetized by injection of a wheal of lidocaine around the ulnar aspect of the wrist to the dorsum of the ulnar styloid at the level of the distal wrist crease.




FIGURE 4-6


Correct needle position for an ulnar nerve block. Lidocaine is injected just proximal to the pisiform bone between the proximal and distal creases of the wrist.


After adequate anesthesia has been achieved and plaster or fiberglass splints are ready for application, reduction can be attempted. If finger traps are available, they are helpful in disimpacting the fracture fragments before reduction.


The patient holds the elbow adducted to the side, the wrist is extended, and the MCP joint is flexed maximally. The examiner grasps the shaft of the flexed proximal phalanx and uses it as a lever arm to push the metacarpal head dorsally. At the same time, the examiner applies counterpressure just proximal to the fracture site at the dorsum of the metacarpal ( Fig. 4-7 ).




FIGURE 4-7


Method of reduction for metacarpal neck fracture. The metacarpophalangeal joint is flexed, and the proximal phalanx is used to help reduce the metacarpal neck fracture.


Another reduction technique, the so-called 90-90 method, is also effective. With this method, the MCP, PIP, and DIP joints all are flexed to 90 degrees for the reduction maneuver only. Dorsally directed pressure is applied over the flexed PIP joint while at the same time a volar directed force is applied over the area of the fractured metacarpal ( Fig. 4-8 ). After reduction, the hand should be immobilized in an ulnar gutter splint. The wrist should be positioned at 30 degrees of extension with the MCP joint at 90 degrees and the interphalangeal (IP) joints in extension (if using a gutter splint). A postreduction lateral view radiograph of the splinted hand should be taken to check for fracture alignment.




FIGURE 4-8


The 90-90 method of reducing a metacarpal neck fracture. The metacarpophalangeal, proximal interphalangeal (PIP), and distal interphalangeal joints all are flexed to 90 degrees. Dorsally directed pressure is applied to the flexed PIP joint while a volar-directed force is applied over the apex of the fracture.


Follow-up Care


Nondisplaced fractures of the second or third metacarpal need follow-up radiographs within 4 to 5 days to look for angulation or malrotation. Any amount of change in position is an indication for prompt orthopedic referral. For fourth or fifth metacarpal fractures, repeat AP and lateral radiographs should be obtained within 7 to 10 days to evaluate whether the reduction position has been maintained. If the fracture is significantly more angulated than in the prereduction radiographs or the reduction has slipped back to its original position, orthopedic referral should be considered. If fracture alignment is maintained, the patient can be seen again in another 2 to 3 weeks.


Most metacarpal neck fractures heal after 4 weeks of immobilization. If compliance with a splint is a concern or the patient prefers a cast, the splint can be converted to a cast. A short-arm cast is applied with the wrist in 30 degrees of extension and MCP joints in 90 degrees of flexion. The cast extends to the palmar crease on the volar side and to the PIP joints on the dorsal side. If gutter splinting is used, PIP and DIP motion are begun when the splint is discontinued.


Complications


Stiffness of the MCP and PIP joints is not uncommon after a metacarpal neck fracture. The stiffness may be the result of prolonged immobilization, tendon adhesions, or interosseous muscle contracture. More aggressive hand rehabilitation under the supervision of a physical or occupational therapist will help the patient regain motion and function. Malunion with apex dorsal angulation can occur; the farther the fracture is from the MCP joint, the more likely it is that the deformity will cause a painful grip, a prominence of the metacarpal head in the palm, or pseudoclawing. Rotational malunion also occurs and is more common in the second and fifth metacarpals. Patients with a symptomatic malunion should be referred for consideration of a corrective wedge osteotomy.


Return to Work or Sports


After immobilization, the patient should begin ROM exercises of the MCP joint and handgrip strengthening (e.g., squeezing a rubber ball). Patients should avoid contact sports for 4 to 6 weeks after immobilization to reduce the risk of reinjury.


Major determinants for return to sports participation include the fracture type and stability, as well as the athlete’s sport and position played. The athlete may return to play after full or near-normal ROM has been achieved and clinical (although not necessarily radiographic) evidence of fracture healing exists. This usually requires 4 to 6 weeks. Depending on the athlete’s sports and position played, the athlete may return to play earlier with adequate external protection.


An alternative therapeutic option for athletes who wish to continue to compete during the period of immobilization is the so-called glove cast. A fiberglass cast is applied just distal to the distal palmar crease of the wrist. The cast extends to the neck of the metacarpals and is circumferential across the dorsal and palmar sides of the hand, including the thenar aspect and the ulnar border ( Fig. 4-9 ). This cast allows maximal finger and wrist function while still protecting the fracture site.


Mar 11, 2019 | Posted by in CRITICAL CARE | Comments Off on Metacarpal Fractures
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