Operative Treatment of Metacarpal Fractures
Operative Treatment of Metacarpal Fractures
DEFINITION
Hand metacarpals can fracture at their base, shaft, neck, or head. Such fractures can lead to shortening, rotation, or angulation.
Metacarpals provide a base for each finger and injury to a metacarpal can severely compromise independent digital function.
Treatment strategy for metacarpal injuries must consider the ability of the human hand to compensate for such injuries.
ANATOMY
The thumb metacarpal (first) is highly independent and is stabilized by its carpometacarpal (CMC) joint and supporting muscles.
The other four metacarpals (second to fifth) are tightly connected through the CMC joints proximally and the deep transverse metacarpal ligaments distally. These ligaments connect the volar plate and head of each metacarpal to the adjacent metacarpal. The ligaments also have a significant role in preventing shortening and rotation of fractures of the central (third to fourth) metacarpals (FIG 1).
The thumb metacarpal has a round cross-sectional shape, whereas the other metacarpals tend to have a triangular shape with a dorsal, anterolateral, and anteromedial facets (FIG 2A).
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FIG 1 • The deep transverse metacarpal ligaments (shaded yellow) protect the fractured metacarpal from excessive shortening and rotation.
The dorsal and volar interosseous muscles cover the ulnar and radial surfaces of each metacarpal (see FIG 2A). These muscles provide blood supply to the metacarpals but are also at risk of contracture in cases of injury leading to severe hand edema and compartment syndrome.
The deep palmar arch and the deep branch of the ulnar nerve lie just volar to the metacarpals and are at risk during fracture and surgery.
On either side of the metacarpal head, there are fossae and tubercles that create a recess from which the collateral ligaments of the metacarpophalangeal (MP) joint arise (FIG 2B).
The extensor tendons lie just superficial to the base and shaft of each metacarpal. At the level of the metacarpal head, they contribute to the dorsal extensor apparatus of each finger (see FIG 2B).
PATHOGENESIS
Axial load is the most common injury mechanism for a metacarpal fracture. Due to the normal curvature of the fifth metacarpal, such an axial load will include a bending
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component and lead to an apex dorsal fracture at the neck, also known as a boxer's fracture (FIG 3A).
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FIG 2 • A. The metacarpals have a triangular shape. The interosseous muscles cover the radial and ulnar surfaces of the metacarpals. The extensor tendons are in close proximity to the dorsal surface. B. The dorsal apparatus covers the MP joint. The extrinsic extensor tendons extend the MP joint and the intrinsic tendons flex it.
Axial loads may also be transmitted proximally on the metacarpal and lead to a CMC fracture-dislocation. Torsional injuries will lead to spiral oblique fractures (FIG 3B).
Bending injuries from direct impact may lead to short oblique or transverse metacarpal fractures (FIG 3C). The addition of butterfly fragments and comminution is dependent on a combination of additional loads.
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FIG 3 • A. Fracture of the neck of the fifth metacarpal with a flexed, apex dorsal angulation (boxer's fracture).
B. Torsional injuries lead to long oblique fractures with a risk for malrotation. C. Short transverse fracture from a direct impact. D. Crush injuries can lead to a combination of injuries with an increased risk of compartment syndrome and significant stiffness. The shortened fourth metacarpal pulls the head of third metacarpal in a proximal and ulnar direction through deep transverse metacarpal ligament. E. Neglected fight bite injury ultimately leading to loss of the metacarpal head.
Crush injuries can lead to comminuted fractures with significant soft tissue injuries and a heightened risk of compartment syndrome (FIG 3D).
NATURAL HISTORY
Metacarpal fractures are mainly affected by shortening and rotation. The effect of these two components is minimized in the central metacarpals due to the stabilizing effect of
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the deep transverse metacarpal ligaments and the bordering intact metacarpals. This stabilizing effect is lost in
cases of multiple metacarpal fractures and more severe injuries (see FIG 3D).
Shaft fractures of the third and fourth metacarpals tend to do well with minimal intervention. Border metacarpals are more prone to shortening and rotation.
Every 2 mm of shortening of the metacarpal can lead to a 7-degree lag at the MP joint.12
Fractures of the metacarpal neck typically result in apex dorsal angulation, which may lead to significant shortening. The increased mobility afforded by the ulnar CMC joints allows more tolerance of angulation in the ulnar metacarpals (fourth and fifth). Whereas some have accepted up to 70 degrees, most authors have
recommended intervention if the angulation exceeds 30 to 40 degrees.4,6,9 The radial metacarpals (second to third) have stiffer CMC joints, and correspondingly, the tolerance for angulation is reduced to only 10 to 15
degrees.7
Thumb metacarpal extra-articular base and shaft fractures can easily tolerate 30 degrees of angulation due to its highly mobile CMC joint.1
Fractures of the metacarpal head with a significant gap or step-off, or fractures that involve a significant portion of the articular surface, should be considered for open reduction and stabilization.2
PATIENT HISTORY AND PHYSICAL FINDINGS
History: Note the mechanism of injury, time since injury, and any treatment received so far. Also, note the age, vocation, and hobbies of the patient. Comorbidities should also be recorded.
Inspection: The skin needs to be checked for any signs of an open fracture. A small laceration near the MP joint may be the only sign of a “fight bite” injury which requires urgent débridement to prevent joint and bone infection (FIG 3E). Also, note digit malrotation and extension lag at the MP and proximal interphalangeal (PIP) joints. A severely edematous hand may signal compartment syndrome or an internal degloving injury.
Palpation: The neurovascular examination should include checking activation of the first dorsal interosseous muscle to confirm activity of the motor branch of the ulnar nerve. Tense compartments and pain with passive motion may signal a developing compartment syndrome.
IMAGING AND OTHER DIAGNOSTIC STUDIES
The posteroanterior (PA) view can show shortening, especially relative to the adjacent metacarpals. Fracture angulation can be seen on the lateral view but is often best seen on the oblique view. Fractures of the base of the fifth metacarpal are best seen on the pronated oblique view.
Specialized views of the metacarpal head can show the volar aspect (Brewerton) or the dorsal aspect (skyline).
Traction views in the anesthetized patient may help elucidate pattern and extent of injury.
Computed tomography (CT) scan can help in extensively comminuted fractures or articular injuries.
DIFFERENTIAL DIAGNOSIS
Open fractures
Fight bite with bacterial inoculation of the MP joint Pathologic fractures
NONOPERATIVE MANAGEMENT
Shaft fractures that are not displaced and not angulated can be treated with a brief period of immobilization followed by protected activities. Those with angulation of greater than 20 degrees (30 on the small finger) deserve an attempt at closed reduction (FIG 4A).
Acute (<7 to 10 days), isolated fourth or fifth metacarpal neck fractures angled more than 30 to 40 degrees benefit from reduction and immobilization. Only 15 degrees should be accepted for the second or third metacarpals. A dorsally directed force can be applied to the head of the metacarpal through the Jahss maneuver (FIG 4B) or directly on the metacarpal head (FIG 4C).
The position of the MP joint during immobilization for treatment of fifth metacarpal neck fractures has not been
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shown to affect the final mobility of the MP joint.14 It is often easier to immobilize the MP joint in extension while applying direct pressure on the metacarpal head (FIG 4D,E).5
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FIG 4 • A. Angled metacarpal shaft fractures deserve an attempt at closed reduction. B. Jahss maneuver. A dorsally directed force is applied to the flexed PIP joint while the metacarpal is stabilized proximally. (continued)
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FIG 4 • (continued) C. Metacarpal neck reduction applying force at the metacarpal head itself while stabilizing the metacarpal shaft proximally. D. Fourth metacarpal shaft fracture reduction being stabilized with pressure directly on the metacarpal head. Note the MP joint is maintained in extension. E. MP flexion on the day of cast removal after being casted for 4 weeks.
Be aware that prolonged immobilization of MP joints in extension may lead to collateral ligament contracture and result in difficulty regaining MP flexion.
SURGICAL MANAGEMENT
Indications for surgery include open fractures, open joint injuries (such as fight bites), malrotated fractures, unstable fractures, and those associated with other injuries that need surgery such as tendon or nerve lacerations.
Relative indications for surgery include extensor tendon lag, metacarpal shortening, prominence of the metacarpal head in the palm, multiple metacarpal fractures, and intraarticular fractures.
Contraindications for internal fixation include grossly contaminated fractures and infirmed patients.
Contaminated fractures should be débrided and temporarily stabilized until definitive fixation can be performed.
Percutaneous pins have the advantage of minimizing soft tissue injury. However, the fracture must be reducible through closed means.
Percutaneous pins can be placed in a retrograde direction from distal to proximal entering the metacarpal through the collateral recesses. This technique allows stabilization of proximal neck or shaft fractures. Flexion of the MP joint facilitates access to the collateral ligament recesses.
Antegrade pin fixation (bouquet pinning) from proximal to distal can provide stability to shaft and neck fractures. This technique has the advantage of avoiding the MP joints altogether, which, if enough stability is present, may even permit early motion. In the treatment of neck fractures, it may lead to less MP stiffness
compared to retrograde (collateral recess) pinning.10 However, placement of the antegrade wires can be more challenging technically.
There are many occasions when the fracture cannot be easily reduced through closed techniques and open approach is required. Such an approach allows for an anatomic reduction and placement of stable fixation. However, it also introduces a degree of soft tissue insult.
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Screws provide rigid fixation while at the same time minimizing implant bulk. However, they are appropriate only for long oblique or spiral fractures whose lengths are at least twice the diameter of the bone at the level of the fracture.
Plates provide rigid fixation in short oblique and transverse fractures but require significant soft tissue dissection. Rarely, the hardware will have to be removed once the fracture is healed.
External fixators allow treatment of more complex fractures while minimizing soft tissue injury but do not allow precise control of the fracture fragments. External fixation may be desirable in the treatment of injuries with massive soft tissue disruption.
Preoperative Planning
The fracture itself and its character will dictate much of the approach to the fracture. However, respect of the soft tissue is of utmost importance.
Crush injuries with significant degloving of the soft tissues may be best managed with limited or percutaneous approaches to limit further embarrassment of the tissue envelope.
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FIG 5 • A. Missing fourth metacarpal shaft and base after gunshot wound. Patient had tenuous dorsal skin. Metacarpal head temporarily stabilized with buried pins from fifth metacarpal. B. Once the soft tissues stabilized, the metacarpal was grafted from the iliac crest and stabilized with plate and screws to the hamate.
C. Dorsal sensory branch of the ulnar nerve travelling through the center of the wound on a different patient.
Grossly contaminated wounds, or those with tenuous soft tissues, may be best managed initially with limited fixation until more definitive fixation can be performed (FIG 5A).
Bone grafting may also need to wait until the soft tissues have stabilized (FIG 5B).
The need to address nerve, vessel, or tendon injuries may also affect the approach (FIG 5C).
Positioning
Most hand fractures are addressed with the patient supine and the hand on a hand table. Concomitant injuries or conditions may affect access to the hand.
Regional or general anesthesia is most commonly used for metacarpal fractures. Local anesthesia may be
appropriate in some circumstances.
Approach
Most fractures are approached dorsally due to the proximity of the bone to the skin and the ease of handling the extensor tendons and dorsal sensory nerves. The border metacarpals may also be approached through their respective subcutaneous borders to further minimize soft tissue insult.
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Dorsal incisions provide excellent exposure of the dorsal aspect of the metacarpals. The incision is best made to the side of the metacarpal, on its border, to minimize extensor tendon irritation. In case of adjacent fractures, the incision is made between the metacarpals. A proximal incision provides access to the base of the metacarpal for percutaneous pinning and a distal incision can give access to the head of the metacarpal. The extensor tendons are retracted to either side for base and shaft fractures.
A dorsal approach to the head and neck will often require division of the juncturae tendinum, which should be repaired at the end of the procedure. If the MP joint must be exposed, the extensor tendon is best split longitudinally. In the case of the index finger, the split is made between the extensor digitorum communis (EDC) and extensor indicis proprius (EIP). For the small finger, the exposure will be between the EDC and extensor digitorum minimi (EDM) (FIG 6).
Coronal shear fractures of the head and neck may require a volar approach. A volar longitudinal incision is made similar to a trigger finger incision. The A1 pulley is opened. The approach is extended proximally and the flexor tendons are retracted to reveal the neck of the metacarpal.
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FIG 6 • Dorsal approach to the MP joint of an index finger. Extensor tendon beneath top retractor. Capsule grabbed by pickup forceps. Articular cartilage seen deep to capsule.
TECHNIQUES
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Closed Reduction and Pin Fixation of Metacarpal Fractures
Retrograde Collateral Recess Pinning
Retrograde fixation (TECH FIG 1A) can be used in proximal and some distal metacarpal shaft fractures (TECH FIG 1B,C).
The MP joint is flexed 70 to 90 degrees, and a 0.035 to 0.045 smooth Kirschner wire (K-wire) is inserted through the skin and the collateral recess into the distal metacarpal. The position of the wire is confirmed with fluoroscopy.
The fracture is anatomically reduced using closed means which can include three-point bend, traction, and rotation.
The wire is advanced into the neck, across the fracture, to the base of the metacarpal while maintaining the reduction. A second wire is placed through the opposite recess in a similar manner (TECH FIG 1D,E).
The K-wires are either cut below the skin (author's preference) or left external, and the hand is immobilized with a forearm-based splint with the MP joint in 70 to 90 degrees of flexion while allowing motion of the interphalangeal (IP) joints.
The pins are removed at 4 weeks and a motion program is instituted. A removable splint is used for an additional 2 weeks.
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TECH FIG 1 • A. Retrograde (collateral recess) pinning. B,C. Angled distal metacarpal fracture. (continued)
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TECH FIG 1 • (continued) D,E. Fracture stabilized with two pins that have been advanced to the base of the metacarpal. (Copyright Thomas R. Hunt III, MD, DSc.)
Antegrade Bouquet Pinning
This technique requires a rotationally stable fracture that can be reduced through closed means (TECH FIG 2A).
An incision is made at the base of the metacarpal. Careful dissection is carried through the soft tissues protecting the cutaneous nerve branches. The extensor tendons are retracted and the metaphysis of the base of the metacarpal is exposed.
In the case of a fifth metacarpal, it is easier to make this approach straight ulnar as opposed to dorsal (TECH FIG 2B).
A unicortical 2.7- or 3.5-mm tunnel is made with a drill. This tunnel is created angled in a proximal to distal direction (TECH FIG 2C).
Commercially available sets include an awl that helps in establishing the tunnel through which the definitive fixation is placed.
Two or three prebent wires (TECH FIG 2D) are then advanced through the tunnel, across the fracture, and lodged into the metacarpal head subchondral bone (TECH FIG 2E).
Great care must be exercised advancing the wires to prevent them from penetrating through the opposite cortex.
The wires can be advanced with a needle holder or a pin holder using some gentle oscillation.
The hand is initially immobilized in a forearm-based splint with the MP joint in 70 to 90 degrees of flexion while allowing some motion of the IP joints.
If stable fixation is accomplished early, MP joint motion is initiated. The affected finger can be buddy taped to the adjacent finger to avoid rotational forces across the fracture.
The wires may be removed after 4 weeks or, if cut at the level of the bone, they may be left in place indefinitely.
Transverse Pinning
Transverse wires are sometimes necessary because the medullary canal of the metacarpal is too small to accommodate intramedullary wires (TECH FIG 3A).
This technique can be used to stabilize distal metacarpal base and shaft fractures that have an adjacent intact metacarpal. It
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is appropriate for border metacarpals with enough intact distal (or proximal) metacarpal to accommodate two distal wires.
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TECH FIG 2 • A. Angled metacarpal neck fracture. B. Incision at the ulnar base of the fifth metacarpal, exposing the insertion of the extensor carpi ulnaris (ECU) on the base of the metacarpal. Incision located on ulnar aspect of metacarpal to minimize irritation of the extensor tendons. C. Unicortical tunnel at the base of the metacarpal. D. Sample of prebent pin. Tip is angled to facilitate passage through the shaft. E. In metacarpal neck fractures or those at risk of shortening, it is important to bring the pins to the subchondral bone of the metacarpal head but not violate the head.
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TECH FIG 3 • A. Second metacarpal fracture with an intact adjacent metacarpal and a narrow medullary canal. B. Fixation using one proximal pin to secure the shaft and two distal pins to secure the distal fragment. C,D. Fracture where the narrow medullary space made it difficult to pass a second wire through the canal. Supplemental fixation achieved through a transverse pin on the distal fragment.
The fracture is anatomically reduced through closed means.
The proximal fragment is first stabilized by pinning it to the adjacent intact metacarpal.
Use the nick and spread technique while placing the wires to minimize the risk of iatrogenic cutaneous nerve injury.
Keep pressure between the adjacent metacarpals to prevent convergence between the metacarpals as the wire is advanced.
Be mindful of the arch-like arrangement of the metacarpals.
The distal fragment is stabilized by placing two wires through the distal fragment into the adjacent intact metacarpal (TECH FIG 3B).
The hand is immobilized in a forearm-based splint with the MP joints flexed 70 to 90 degrees while the pins are in place. The pins are kept for 3 to 4 weeks. The IP joints are left free to move.
The pins are removed at 3 to 4 weeks, and the hand is placed in a removable splint for an additional 2 weeks.
Alternatively, transverse pins can be used to augment other forms of fixation or control rotation (TECH FIG 3C,D).
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Open Reduction and Plate/Screw Stabilization of Metacarpal Fractures
Dorsal Approach for Fixation
Fractures that cannot be reduced through closed means require an open approach (TECH FIG 4A-C).
A longitudinal incision is made parallel and adjacent to the metacarpal. If two metacarpals are fractured, the incision can be made between the metacarpals.
The sensory nerve branches are protected. The extensor tendons are retracted. If a junctura tendinum is in the area of the fracture, it can be divided but should be repaired at the end of the procedure.
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TECH FIG 4 • A-C. Patient with torsional injury to long and ring fingers leading to spiral fractures of the third and fourth metacarpals. The combined injury made it possible for malrotation to develop. D.
Reduction is maintained with a reduction clamp. E,F. Fracture stabilized with 1.5-mm screws. One screw is perpendicular to the fracture to compress fracture and the other is perpendicular to the metacarpal to stabilize axial loads. (continued)
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TECH FIG 4 • (continued) G,H. Motion at 6 weeks after surgery.
The periosteum is elevated at the fracture site to assist with assessment of fracture reduction. As much of the interosseous muscle is left attached to the metacarpal as feasible to preserve blood supply to the bone.
The fracture is reduced and provisionally stabilized with reduction clamps (TECH FIG 4D).
Lag Screw Fixation
Long oblique and spiral fractures whose lengths are at least twice the diameter of the bone at the level of the fracture are amenable to limited fixation with screws only (see TECH FIG 4A-C).
Appropriately sized lag screws (1.4 to 2.7 mm) are placed. Typically, two or three screws are used (TECH FIG 4E,F).
The first screw is placed perpendicular to the fracture in order to compress it and the second screw is placed perpendicular to the bone to resist longitudinal forces.
In order to get proper compression with a lag screw construct, it is important to overdrill the near cortex.
When using a 2.0-mm screw system, a 1.5-mm drill bit is used to drill both cortices. The near cortex is then overdrilled with a 2-mm drill bit.
A countersink is used to maximize contact between the head of the screw and the bone. The size of the screw is measured and an appropriately sized screw is placed.
The periosteum and interosseous muscle fascia are reapproximated to cover the screws. The juncturae tendinum are repaired and the skin is closed in standard fashion.
The hand is then immobilized with the MP joints flexed 70 to 90 degrees with a forearm-based splint. Early motion can be started as early as 4 to 7 days, depending on fracture stability (TECH FIG 4G,H).
Plate and Screw Fixation
Short oblique and transverse fractures that require an open reduction are well stabilized with plates and screws.
Short oblique fractures are most often treated using a neutralization plate combined with lag screws (TECH FIG 5A-D).
Transverse fractures benefit from compression plating (TECH FIG 5E,F).
Using the approach detailed earlier, the fracture is exposed and the periosteum is elevated at the fracture site to assist with the fracture reduction.
The fracture is then provisionally stabilized with a reduction clamp or wires.
Short Oblique Fractures
In the case of a short oblique fracture, the fracture is stabilized using the lag screw technique mentioned earlier. A neutralization plate is added for additional stability (see TECH FIG 5C,D).
Typically, 2.0- to 2.7-mm plates and screws are used (see TECH FIG 5D).
The plate should be prebent into a slight concave configuration to accommodate the normal curvature of the metacarpal and to provide mild compression when indicated.
The fixation should include at least two bicortical screws on either side of the fracture.
When drilling in a dorsal to volar direction at the base of metacarpals, it is important to very carefully drill the opposite cortex. The motor branch of the ulnar nerve is in the vicinity and can be injured. Using the drill in the oscillating mode can help prevent such injuries.
In some cases, the lag screw may be placed through a hole in the plate depending on fracture configuration and plate placement.
The plate is first secured to one fragment with one or two centrally drilled bicortical screws. Two additional screws are then placed in the opposite fragment.
If the fracture has already been compressed through a lag screw, these final screws can be placed centrally in the plate holes in a static mode (see TECH FIG 5C,D).
Fracture fixation is completed once at least two bicortical screws are placed on either side of the fracture.
Transverse Fractures
Transverse fractures do not provide the opportunity to compress the fracture through lag screws. In such situations, the fracture is compressed using the compression plate technique (see TECH FIG 5E,F).
The plate is bent into a slight concave configuration to allow compression of the far cortex once the plate is secured to
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the bone. It is positioned about the fracture such that at least four cortices of fixation can be obtained both proximal and distal to the fracture.
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TECH FIG 5 • A,B. Short oblique fracture of the metacarpal. C,D. Fracture stabilized with a lag screw and a neutralization plate. E,F. Short transverse fracture of the second metacarpal stabilized with a compression plate. (C,D: Copyright Thomas R. Hunt III, MD, DSc.)
The first bicortical screw is placed in one of the screw holes closest to the fracture.
The second screw is placed on the opposite side of the fracture in the screw hole on that side that is closest to the fracture. This screw is placed in a compression mode.
The screw hole is drilled eccentrically in the hole, as far from the fracture as possible.
The remaining screws may be placed in either a compression or static mode.
In cases of simple fractures with minimal comminution, nonlocking plates are appropriate, but locking plates may be considered in fractures with osteopenic or missing bone.
The periosteum is closed over the plate to protect the overlying tendons. The juncturae tendinum are repaired. The skin is closed in a standard fashion.
A splint in the functional position is applied to maintain the MP joints flexed 70 to 90 degrees for 4 to 7
days. The patient is then able to start a motion program.
Radiographic confirmation of consolidation of transverse fractures can be delayed in which case clinical judgment has to be made as to when to allow unrestricted activities.
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Dorsal Approach with Stabilization of Metacarpal Head Fractures
Displaced intra-articular fractures can benefit from an open reduction and fixation (TECH FIG 6A,B). A dorsal approach is performed with a longitudinal incision over the metacarpal head.
In the case of the third and fourth metacarpals, the extensor digitorum is split longitudinally.
In the case of the second metacarpal, the extensor tendon is split between the fibers of the EDC and EIP.
In the case of the fifth metacarpal, the extensor is split between the fibers of the EDC and the EDM.
The tendon fibers are separated from the underlying capsule. The capsule is split longitudinally and the fracture is exposed (TECH FIG 6C).
The fracture is then visualized and disimpacted.
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TECH FIG 6 • A,B. Intra-articular head fracture of the fourth metacarpal. C. Dorsal approach to an MP joint. Extensor tendon beneath top retractor. Capsule grabbed by pickup forceps. Articular cartilage seen deep to capsule. D,E. Intra-articular fracture stabilized with headless screws. (continued)
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TECH FIG 6 • (continued) F,G. Intra-articular head fracture stabilized with extra-articular screws.
Once reduction is attained, it is maintained with a reduction clamp.
A guidewire for a cannulated headless screw is then placed perpendicular to the fracture.
The size of the bony fragment should also be at least three times the diameter of the desired screw. The wire is advanced up to the cortex in the opposite fragment.
A depth gauge is used to determine the proper length of the screw. The screw should be 2 to 4 mm shorter than the measured length.
A cannulated drill bit is then used to prepare the track for the screw.
The guidewire can be advanced through the opposite cortex to prevent accidental removal while drilling for the screw.
A properly sized screw is placed across the fracture and advanced beneath the articular surface (TECH FIG 6D,E).
An additional screw can be placed for increased stability.
Alternatively, the fracture can be stabilized with traditional-headed screws (1.5 to 2.4 mm) (TECH FIG 6F,G). These are placed from the nonarticular portion of the fracture after drilling up to, but not through, the articular surface. If a headed screw has to be placed through the articular surface, it must be countersunk beneath the cartilage.
The capsule is closed with absorbable suture. The split in the extensor tendon is repaired with nonabsorbable suture. The skin is closed in standard fashion.
The patient is then splinted with the MP joints flexed 70 to 90 degrees for 4 to 7 days. The patient may then begin an early motion program.
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Volar Approach with Stabilization of Metacarpal Head Fractures
Coronal fractures that extend into the metacarpal neck provide the opportunity to address the fracture without opening the MP joint and therefore minimizing the risk of MP joint contracture (TECH FIG 7A,B).
A longitudinal incision is made on volar aspect of the A1 pulley. The pulley is opened and the flexor tendons are retracted.
The metacarpal neck and the fracture are exposed. This will require division of the periosteum and volar plate.
The fracture is reduced and held in place with a reduction clamp or temporary K-wires.
The fracture is then stabilized with at least two bicortical screws (1.5 to 2.0 mm) using the lag screw technique previously discussed (TECH FIG 7C,D).
The screws must be countersunk.
The volar plate and periosteum are then repaired to cover the screw heads. The A1 pulley is left open. The skin is closed in standard fashion.
The patient is then splinted with the MP joints flexed 70 to 90 degrees for 4 to 7 days. The patient may then begin an early motion program.
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TECH FIG 7 • A,B. Coronal intra-articular fracture that extends to the metacarpal neck. C,D. If there is no comminution, the fracture can be addressed through a volar approach and stabilized with lag screws.
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PEARLS AND PITFALLS |
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Natural ▪ Many metacarpal fractures can do exceedingly well with minimal intervention. history
Fight bites ▪ Be vigilant of small lacerations near the MP joint, which may be the only sign of a fight bite that needs urgent débridement to prevent a devastating infection.
Severe ▪ Polytrauma patients with severe hand injuries are at risk of missed injuries, open trauma fractures, compartment syndrome, and intrinsic contracture. |
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Mobilization ▪ Allow tendon-gliding exercises as early as possible to minimize scar formation.
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Critical structures can be protected during drilling by using the oscillation mode.
Drilling
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Pins can be used to manipulate the fracture to a reduced position.
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Sometimes, it is easier to apply the plate to one side of the fracture and then perform the reduction and fixation to the opposite side of the fracture.
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Always check finger rotation prior to completing fixation.
Fracture reduction
POSTOPERATIVE CARE
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Immobilization in the postoperative period will depend on the stability of the reconstruction and the status of the soft tissues.
Fractures stabilized with retrograde (collateral recess) or transverse pins should be immobilized with the MP joints flexed 70 to 90 degrees for 3 to 4 weeks while the pins are in place. The IP joints should be allowed to move to minimize stiffness.
Fractures stabilized with antegrade (bouquet) pins should be immobilized with the MP joints flexed 70 to 90 degrees for 3 to 4 weeks. Some authors allow early motion of the MP joint with bouquet pinning,
understanding that there may be some loss of reduction.3
Fractures that have been stabilized with rigid fixation such as plates or screws should be immobilized in a splint with the MP joints flexed 70 to 90 degrees for 4 to 7 days. An early motion program can then be instituted. A removable splint in the functional position should be used for protection until fracture stability.
A hand therapist can be consulted if significant stiffness or lack of progress is noted during the early recovery period. However, in patients with severe injuries, it is often best to start therapy early.
Protected activities should continue until fracture stability, which is often at least 4 to 6 weeks. In cases of delayed union, bone grafting can be considered.
If plates are bothersome, they can be removed as early as 4 to 6 months after fracture consolidation.
OUTCOMES
Metacarpal shaft fractures with limited shortening (2 to 5 mm) do well without surgery due to the stabilizing effect of the adjacent metacarpal and supporting ligaments.8
Fractures of the fifth metacarpal neck that have healed with significant angulation of up to 70 degrees can have satisfactory outcomes.6,15
Percutaneous pins can stabilize the reduction of many distal and proximal metacarpal shaft fractures. In the treatment of metacarpal neck fractures, antegrade (bouquet) pinning may lead to less stiffness of the MP joint compared to retrograde (collateral recess) and transverse pinning.10,16
Plate fixation of short oblique, transverse, or multiple metacarpal fractures can provide the necessary stability to start an early motion program but on occasion will require hardware removal.11
Screw fixation of articular head fractures can stabilize the fracture, but a degree of stiffness of the MP joint is expected.13
COMPLICATIONS
Some degree of stiffness affects the surgical treatment of most metacarpal fractures.
Stiffness of the MP joint can originate from contracture of the collateral ligaments and capsule after a period of immobilization. It may also occur from adhesions of the extensor tendons, especially after an open approach. Early mobilization as tolerated by the fixation can minimize it.
Extension lag may develop from fracture shortening or tendon adhesions. Loss of articular congruity of the metacarpal head may block motion.
Malrotation is poorly tolerated by most patients and should be addressed surgically.
The dorsal sensory branches of the ulnar and radial nerve are very sensitive to manipulation.
The deep motor branch of the ulnar nerve can be caught in the cutting tips of an inadvertent drill passage.
Even though nonunions of metacarpal are rare, delayed unions can be seen, especially in short transverse fractures treated with a plate. If a nonunion does develop and the plate breaks, consideration should be given to bone grafting and revision fixation.
Pin site infections can often be treated with oral antibiotics until the pins can be safely removed.
REFERENCES
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