Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

273. Operative Treatment of Metacarpal Fractures

Christopher L. Forthman and Thomas J. Graham

DEFINITION

images Metacarpal fractures are most significant when they disrupt function of the associated digit.

images The treatment of metacarpal fractures affects finger function and must be weighed against the sequelae of the fracture itself.

images Intra-articular fractures may involve the carpometacarpal (CMC) joint or metacarpophalangeal (MCP) joint.

images CMC joint injuries are discussed in other chapters.

images Intra-articular MCP joint fractures have an increased risk of stiffness and posttraumatic arthritis.

ANATOMY

images The metacarpals are long tubular bones with relatively flat surfaces dorsally. The medial and lateral cortices converge volarly, making the cross-section triangular. The bone may be quite narrow in the mid-diaphyseal region, with the fourth metacarpal being particularly gracile.

images Dorsal and volar interossei muscles envelop the medial and lateral surfaces. When undisturbed, the muscles provide abundant blood supply to the underlying bone (FIG 1A). When severely disrupted, the muscles have the potential for disabling scarring and “intrinsic contracture.”

images Deep transverse intermetacarpal ligaments lie at the level of the metacarpal neck and limit deformity with typical lowenergy injuries.

images Intact ligaments limit shortening to about 5 mm.

images

FIG 1  A. Anatomy of the metacarpals. Each metacarpal crosssection is roughly triangular, with intrinsic musculature on both sides and the extensor tendon on the dorsal surface. B. The metacarpophalangeal joint movers. The metacarpophalangeal joint is enveloped by a complex system of motors, including the extension moment generated by the extensor apparatus and the flexion power provided by the intrinsic muscles of the hand.

images The extensor apparatus envelops the MCP joint (FIG 1B). Proper collateral ligaments originate from a tubercle on the metacarpal head and may contribute to posttraumatic MCP joint contracture (see Chapter HA-108). The adjacent lateral furrow or so-called collateral recess allows passage of the interosseous tendon and may serve as a portal of entry for Kirschner wire fixation into the intramedullary canal.

PATHOGENESIS

images Metacarpal fractures typically result from one of two mechanisms of injury:

images Most commonly, an axial load is transmitted from the MCP joint down the shaft of the metacarpal. Such injuries include the spectrum of fractures from a low-energy fifth metacarpal neck “boxer's fracture” to a high-energy comminuted shaft fracture caused by a blow from the steering wheel in a motor vehicle collision.

images The metacarpal less commonly is injured by a crush-type injury that flattens the metacarpal arch bridging the carpus to the phalanges. Crush injuries typically involve multiple metacarpals and are often associated with other fractures and significant soft tissue trauma.4

images Extra-articular fracture orientation may be characterized as transverse, oblique, or spiral, and with or without comminution. As with other long tubular bones, the exact pattern depends on the degree of shear and torsion associated with the applied load. The fracture typically has apex-dorsal malalignment secondary to the flexion force applied by the lumbrical and interossei muscles.

NATURAL HISTORY

images Most metacarpal fractures heal uneventfully without surgery.

images Low-energy transverse or oblique fractures of a single metacarpal usually maintain acceptable alignment and heal without any measurable functional deficit.

images Spiral fractures, comminuted fractures, and fractures of multiple metacarpals are more likely to shorten and rotate, resulting in tendon imbalance and overlapping of the fingers.

images Fractures of the metacarpal neck (usually the fourth or fifth) may have varying degrees of apex-dorsal malalignment.

images Flexion of the fourth or fifth metacarpal heads beyond 30 and 45 degrees, respectively, results in a visible pseudoextensor lag and sometimes pain in the palm during grasping.

images Less angulation is tolerated in the index and middle metacarpals as there is less compensatory motion available at the radial-sided CMC joints.

images Cadaveric studies of fifth metacarpal neck “boxer's fractures” have demonstrated that every 2 mm of shortening causes an average of 7 degrees of extensor lag,6 and 30 degrees of angulation results in 22% loss of finger range of motion.1

images Nevertheless, there is no well-defined relationship between angular fracture malalignment and symptoms. However, rotational malalignment is poorly tolerated as it results in digital scissoring and difficulty with grasp.

PATIENT HISTORY AND PHYSICAL FINDINGS

images Physical examination methods include:

images Inspection. The examiner should visualize the fingers as the patient carries them through an arc of motion. All nail beds should point toward the scaphoid tubercle with finger flexion.

images Extensor lag. The examiner should assess the resting posture of the MCP joint and active MCP extension. Apexdorsal malangulation results in some loss of active MCP joint extension.

images Palpation. The examiner should determine the degree of dorsal fracture eminence or palmar metacarpal head prominence. Dorsal callus is usually only a cosmetic concern. The palmar head prominence may be painful with grasp.

images The examination is not complete without carefully assessing for associated injuries:

images Open wound: The most common (and often missed) open wound results from a tooth puncture into the MCP, the socalled fight bite. These injuries should be treated urgently with surgical débridement beforeinfection develops.

images CMC dislocation: Metacarpal base fractures are often associated with CMC joint subluxation or dislocation. These injuries may go unrecognized until a true lateral radiograph of the hand is inspected.

images Carpal tunnel and compartment syndromes: High-energy fractures may result in compartment syndrome, necessitating fasciotomy of the involved intrinsic muscles. Carpal tunnel syndrome may also result, particularly with an associated wrist injury such as a perilunate dislocation.

IMAGING AND OTHER DIAGNOSTIC STUDIES

images Plain radiographs including AP, lateral, and oblique views usually suffice. Radiographs of the contralateral hand may be valuable for comparison at the time of surgery.

images AP view: Sagittal plane malalignment is underestimated. Any coronal plane angular malalignment is likely to be clinically relevant.

images Lateral view: Metacarpal overlap makes the lateral view difficult to analyze. It may be omitted unless there is specific concern for subluxation at the MCP or CMC joints.

images Oblique view: A partially pronated radiograph is the most telling perspective and may be used to measure flexion deformity at the fracture site.

images Traction views may be performed to assess the degree of comminution at the fracture site or to check the mobility of subacute fractures.

images Cross-sectional imaging (CT or MRI) may be considered to evaluate a potentially pathologic fracture or to further define articular fractures and subluxations.

DIFFERENTIAL DIAGNOSIS

images CMC fracture-dislocation

images MCP dislocation

images Fight bite

images Pathologic fracture (eg, enchondroma)

NONOPERATIVE MANAGEMENT

images Nondisplaced and minimally displaced metacarpal fractures should be protected in a thermoplast splint or cast for 3 to 4 weeks, followed by gradual mobilization. The MCP joints should be immobilized in flexion to (1) relax the intrinsic muscles and prevent further deformity at the fracture site and (2) place the MCP collateral ligaments on stretch.

images Apex-dorsal malalignment of the border metacarpals may be partially corrected with reduction and splinting.

images Rotational malalignment cannot be reliably corrected with nonoperative means.

Jahss Maneuver

images Reduction is accomplished under a hematoma block with this maneuver5 (FIG 2).

images The metacarpal shaft is stabilized and the MCP joint flexed 90 degrees.

images While distracting at the fracture site, upward force is applied to the proximal phalanx and metacarpal head to realign the neck and shaft.

images A splint with three-point molding is applied with dorsal compression at the fracture site and volar support for the metacarpal head and base.

images A cast is applied 10 to 14 days later.

images Joint mobilization begins at 4 weeks.

SURGICAL MANAGEMENT

images Surgical reduction and stabilization is indicated for malrotated fractures, open fractures, unstable fractures (especially involving the border metacarpals), or fractures associated with joint disruption, tendon injury, or neurovascular injury.

images Relative indications for surgery include fractures associated with significant extensor lag, palmar metacarpal head prominence, more than 5 mm of shortening, and the presence of multiple displaced metacarpal fractures.

images

FIG 2  Jahss maneuver: correction of apex dorsal malalignment as shown by Jahss in 1938.

images Percutaneous surgical techniques are often adequate for lowenergy metacarpal shaft fractures and for most metacarpal neck fractures.

images Open reduction and internal fixation should be considered for open fractures, shaft fractures with significant comminution, and fractures associated with joint disruption, tendon injury, or neurovascular injury.

images Dorsal plating is the most biomechanically stable fixation,2 although it is potentially more disruptive to the soft tissues than other methods, such as crossed Kirschner wires or interosseous wires.

images Crush-type injuries flatten the bony arch of the hand, often resulting in open metacarpal neck fractures with varying degrees of soft tissue injury. Carpal and CMC joint injuries also occur and are discussed in other chapters.

images Crush fractures associated with mild to moderate soft tissue injury with or without disruption of the extensor mechanism may be stabilized by conventional pinning techniques or by a T-type plate applied distally up to the proximal margin of the joint capsule (FIG 3A,B).

images Occasionally, crush injuries result in long oblique neck fractures, which may be stabilized with lag screws alone (FIG 3C).

images More stable internal fixation is recommended over percutaneous pins when early motion is necessary (eg, associated extensor laceration).

images Crush fractures associated with severe soft tissue injury or internal degloving are best pinned percutaneously (FIG 3D–F).

images The dorsal soft tissues are often tenuous and surgical incisions can result in necrosis and the need for otherwise unnecessary soft tissue coverage procedures.

images Metacarpal fractures resulting from projectiles are graded as either low or high energy.

images

FIG 3  A. Oblique view of the hand demonstrates fourth and fifth metacarpal shaft fractures. B. Repair may be achieved with conventional plates using a T-shape to gain additional fixation in the metaphyseal bone near the metacarpal head or base. C. Long oblique fractures of the fourth and fifth metacarpal heads have been stabilized with multiple lag screws. An adjacent transverse fracture of the ring finger proximal phalanx has been repaired with a plate. D. Clinical photograph of a crushed hand reveals global swelling and splitting of the skin indicative of severe internal degloving. E. Radiograph confirms fracture of all five metacarpals and the carpus. F. Fractures are stabilized with percutaneous pins to avoid additional trauma from surgical dissection.

images Simple comminuted fractures cased by low-energy projectiles with small entry or exit wounds are best treated with limited exposure and débridement, and fracture pinning (FIG 4A).

images Callus usually forms because the fracture fragments, although comminuted, remain vascularized.

images If there is a large area of bone loss, more rigid plate and screw fixation supplemented with bone graft may be safely performed.3

images Complex, comminuted fractures resulting from high-energy projectiles and associated with large open wounds and metal debris should be carefully cleansed, taking measures to minimize devascularization of the fracture fragments.

images Tendons, nerves, and vessels may need to be repaired.

images Provisional fixation with Kirschner wires may be considered if serial débridements are anticipated.

images If and when soft tissues allow, consideration should be given to rigid stabilization of the fractures with a bridge plate technique to facilitate mobilization (FIG 4B).

images Bone grafting may be necessary but can be delayed until there is minimal risk of wound infection (FIG 4C).

images Simple thumb metacarpal shaft fractures usually heal in acceptable alignment with nonoperative management. The massively comminuted thumb metacarpal may be difficult to control in a splint or cast alone. Spanning external fixators are effective for these injuries in order to maintain the first web space while fracture consolidation occurs (FIG 4D,E).

Preoperative Planning

images A surgical technique is selected based on the clinical examination, radiographs, and the surgeon's preference.

images The “best” technique is usually the method that is least disruptive to the soft tissues while allowing early digital mobilization.

images The “best” technique depends on patient factors. For example, a grossly contaminated and devitalized open metacarpal fracture may be treated with percutaneous Kirschner wires to minimize further soft tissue stripping. In contrast, a simple closed transverse metacarpal fracture in a dentist would be considered for dorsal plating to facilitate a prompt return to work.

images The “best” technique also depends on surgeon factors. A surgeon facile with the technique of collateral recess pinning may quickly stabilize multiple metacarpal fractures. A surgeon inexperienced in this technique may spend considerable time and frustration trying to pass wires. Poorly placed percutaneous wires in any technique may cause more soft tissue problems (eg, infection) than open reduction and fixation.

images

FIG 4  A. A radiograph of the hand shows percutaneous fixation of displaced metacarpal fractures from a gunshot wound. B. Higher-energy projectiles may cause considerable displacement and comminution, as shown in this radiograph. Bridge plating is performed to improve alignment while minimizing soft tissue dissection. C. This index metacarpal developed a nonunion and segmental defect after nonoperative treatment of a gunshot-related fracture. A locking plate applied with cancellous bone graft to fill the void resulted in solid healing. D. Fractures of the first ray, as shown in this radiograph, often result in contraction of the thumb–index web space. E. A clinical photograph shows application of an external fixator to allow fracture consolidation in a functional position.

images In the operating room, the contralateral hand is examined, note is made of the patient's native digital rotation, and contralateral radiographs are reviewed to assess appropriate metacarpal length.

Positioning

images The patient is positioned supine with the affected extremity placed on a hand table. A brachial tourniquet is applied.

images Surgery may be performed under regional or general anesthesia.

Approach

images Percutaneous landmarks are described in the Techniques section.

images A single extra-articular metacarpal fracture is approached with a dorsal longitudinal incision.

images Crossing dorsal sensory nerves are sought and avoided, particularly as they pass over the bases of the border metacarpals.

images The extensor mechanism is retracted to one side and the underlying metacarpal exposed in an extraperiosteal fashion.

images At closure, hardware may often be covered by the fascia of the interosseous muscles.

images Multiple metacarpal fractures are exposed by way of separate dorsal longitudinal incisions placed between affected metacarpals. If necessary, each incision may be extended as a Y distally to facilitate exposure of each metacarpal head and neck. Alternatively, the incision may be designed as a lazy S to facilitate exposure of both metacarpals (FIG 5A,B).

images Intra-articular fractures are approached by longitudinally splitting the extensor tendon over the MCP (FIG 5C).

images

FIG 5  A. A longitudinal incision may have legs distally (or proximally) to facilitate exposure of multiple metacarpal heads (bases). B. A curvilinear or S-shaped incision allows the skin to be sewn back for ease of operating without an assistant. C. The index metacarpophalangeal joint capsule is seen after dividing the interval between the extensor indicis proprius and the extensor digitorum communis.

TECHNIQUES

CLOSED REDUCTION AND PINNING OF METACARPAL FRACTURES

images  A multitude of methods for pinning metacarpal fractures have been described.

images We have found collateral recess pinning to be an expedient and elegant technique for managing the wide spectrum of closed and open, simple and comminuted, single and multiple metacarpal shaft fractures.

images In contrast, a technique called bouquet pinning is uniquely suited for neck fractures of the border metacarpals.

images These two techniques are illustrated in view of the technical challenge associated with these procedures.

Collateral Recess Pinning of Metacarpal Shaft or Neck Fractures

images  Obtain gross alignment in a closed fashion (TECH FIG 1A).

images  Flex the MCP joint to facilitate control of the distal fragment and subsequent pin placement (TECH FIG 1B).

images  Place a 0.045-inch smooth Kirschner wire by hand onto the radial (or ulnar) collateral recess and confirm appropriate placement at the deepest concavity of the collateral recess (TECH FIG 1C).

images An oblique or near true lateral view confirms placement in the sagittal plane.

images

TECH FIG 1  A. Malangulated index and middle metacarpal neck–shaft fractures in an elderly woman after a fall down stairs. B. The typical starting point for a collateral recess pin is more distal and volar than the novice anticipates. The site is best obtained with the metacarpophalangeal joint flexed. C. The starting point is confirmed fluoroscopically. D. A 0.045-inch smooth Kirschner wire is driven to the fracture site. E. The fracture is reduced and the wire advanced across the fracture site, down the medullary cavity, and into the metacarpal base. F. The second wire is placed similarly. G. Collateral recess pinning of the middle digit metacarpal.

images  Advance the wire with power into the shoulder of the metacarpal and down the intramedullary canal to the fracture site (TECH FIG 1D).

images  Reduce the fracture and advance the wire, keeping it intramedullary and seating it in the bone of the metacarpal base (TECH FIG 1E).

images Consider advancing the wire using a mallet rather than power in order to “bounce” off the far cortex and remain intramedullary.

images  Pass a second wire, completing fracture stabilization (TECH FIG 1F,G).

images  Reduction and fixation is optimized when the wires cross the fracture site.

Bouquet Pinning of Metacarpal Neck Fracture

images  Make a longitudinal 2-cm incision over the radial aspect of the second metacarpal base and CMC joint (TECH FIG 2A,B) for the index or on the corresponding ulnar side of the small metacarpal base.

images The wrist extensor is elevated partially but not completely detached.

images  Prepare a 0.045-inch smooth Kirschner wire by cutting off the sharp tip, gently bending the pin along its length, and creating a deflection of the pin in the plane of the original bend about 3 mm from its leading end (TECH FIG 2C).

images

TECH FIG 2  A. The contour of the index metacarpal head is distorted on this radiograph due to flexion of the distal fragment in this metacarpal neck fracture. B. A small incision site is marked at the palpable radial base of the index metacarpal. (continued)

images

TECH FIG 2  (continued) C. A 0.045-inch Kirschner wire is precontoured to permit easy passage down the intramedullary canal. D. The wire is directed distally using the acutely angled tip to navigate into the canal and across the fracture site into the head. E. The fracture has been provisionally reduced and held with a single bouquet pin. F. Additional Kirschner wires refine fracture reduction and stabilization. G. A lateral radiograph confirms correction of the apex-dorsal deformity.

images  Locate an entry site into the medullary canal at the proximal aspect of the metaphysis using fluoroscopy.

images  Enter the canal with a 2-mm drill and enlarge the introitus to about 5 mm.

images  Introduce the precontoured 0.045-inch Kirschner wire and direct it distally, at the most acute angle possible (TECH FIG 2D).

images  Advance and direct the wire down the canal and across the reduced fracture site using two large needle holders (TECH FIG 2E).

images  Insert several additional 0.045 or 0.035-inch Kirschner wires to complete the bouquet and maintain the reduction.

images The goal is to tension the wires off the intact proximal cortex and enter the distal fragment in varied locations, creating a “bouquet” effect.

images  Cut the pins flush with the canal and “nudge” them inside with a bone tamp (TECH FIG 2F).

images  A lateral radiograph confirms correction of the preoperative apex-dorsal angulation (TECH FIG 2G).

Alternative Methods

images  The combination of a longitudinal “collateral recess” pin and a transverse pin is a technically simple method of fixation for certain border metacarpal neck and base fractures (TECH FIG 3).

images

TECH FIG 3  A transverse Kirschner wire may be used in lieu of a second collateral recess pin to stabilize metacarpal neck (A) or shaft fractures (B).

OPEN REDUCTION AND INTERNAL FIXATION OF METACARPAL FRACTURES

images  Traditional AO techniques may be used to stabilize metacarpal fractures: long oblique or spiral fractures are secured with multiple screws, while short oblique and transverse fracture patterns require plate fixation.

Dynamic Compression Plating for Transverse Fractures

images  Dynamic compression plating is performed using a dorsal longitudinal approach.

images Incorporate open wounds or previous incisions as needed (TECH FIG 4A).

images  Identify and protect dorsal sensory nerve branches (TECH FIG 4B).

images  Expose the fracture in an extraperiosteal fashion.

images In addition to the dorsum, visualize both the radial and ulnar margins to help guide reduction.

images  Apply the appropriately sized dynamic compression plate to the dorsum of the distal fracture fragment and clamp it proximally to obtain provisional fracture reduction (TECH FIG 4C).

images Plate size and length depend on the patient and the fracture. The most commonly used are 2.0 to 2.5 mm.

images Add a subtle concave bend to the plate before application to the bone to help compress the volar cortices.

images  Assess sagittal and coronal plane alignment by direct inspection of the fracture site; assess rotation clinically with the aid of tenodesis (TECH FIG 4D).

images  Fill screw holes in compression mode, achieving at least four cortices of fixation in both the proximal and distal fragments (TECH FIG 4E).

images  Fluoroscopy confirms anatomic fracture reduction and appropriate hardware placement (TECH FIG 4F,G).

images  Close the periosteum and interosseous muscle fascia over the plate to provide a smooth gliding surface for the extensor mechanism (TECH FIG 4H).

images

TECH FIG 4  A. A malrotated open index metacarpal fracture from an industrial machine accident. B. A branch of the radial sensory nerve crosses the metacarpal. C. A 2.4-mm dynamic compression plate is secured distally with a screw and proximally with a clamp to obtain provisional reduction. D. Digital rotation is inspected. E. In the absence of comminution, the plate may be applied in compression mode. F,G. AP and lateral views demonstrate anatomic reduction and appropriate screw lengths. H. The plate is covered by fascia to minimize extensor tendon irritation.

Neutralization Plating with Lag Screw Fixation for Short Oblique Fractures

images  A short oblique fracture can be compressed with a lag screw and protected with a neutralization plate. In this case of pathologic fracture, a lag screw crosses an enchondroma cavity filled with bone graft. A T-type plate has been selected to optimize distal fixation without disrupting the MCP joint capsule (TECH FIG 5A).

images  The exposure of short oblique metacarpal fractures is similar to transverse fractures. Adequate bone must be exposed proximal and distal to the fracture site to allow at least four cortices of screw fixation (TECH FIG 5B,C).

images  Provisional fracture reduction can usually be achieved with a fracture reduction clamp. If fracture geometry allows, a plate (2.0 to 2.5 mm) can be contoured and held in place without disturbing the reduction (TECH FIG 5D).

images  A lag screw may be placed alone or through the plate. Lag screw placement through the plate reduces soft tissue dissection and improves stability (TECH FIG 5E,F).

images  Screw holes are filled in the remainder of the plate to protect the fracture site (TECH FIG 5G,H). Standard cortical screws may be used, although many modern plate systems also have the option for locking screws to improve fixation in metaphyseal bone.

images

TECH FIG 5  A. Short oblique fractures can be lagged together before placement of a dorsal plate. B. This cadaver specimen demonstrates a short oblique fracture at the proximal metadiaphyseal junction of the index metacarpal. C. Fluoroscopy reveals the proximity of the fracture to the carpometacarpal joint. D. The unstable distal fragment is controlled by a small pointed clamp to facilitate reduction. The reduction is maintained by a second clamp, which may also be used to hold a plate. E. A screw is inserted across the fracture site with lag technique to achieve optimal compression. F. Fluoroscopy confirms the reduction. G. Additional screws are placed, neutralizing forces at the fracture site. H. Final radiograph.

images  Lag screws obviate the need for excessively long plates (TECH FIG 6A). Ideally, one screw is placed perpendicular to the fracture to maximize compression and another screw is placed perpendicular to the intramedullary axis of the metacarpal to resist axial loads.

images  A long oblique ring metacarpal fracture is exposed enough to see the length of the fracture line; however, further proximal and distal dissection is unnecessary as a plate will not be used (TECH FIG 6B). The distal extent of the volar fracture fragment approaches the metacarpal head as clarified by careful fluoroscopic imaging (TECH FIG 6C).

images  Long spiral and oblique fractures typically key into position easily with the aid of a pointed clamp (TECH FIG 6D).

images  Fluoroscopy may be used to confirm reduction as the entire fracture length may be difficult to visualize (TECH FIG 6E). Rotational alignment should also be assessed clinically as described above.

images  Lag screws are placed in different planes to achieve fracture compression and resist loads applied to the metacarpal (TECH FIG 6F).

images  A final lag screw is placed proximally with strict adherence to good technique in order to avoid splintering of the metacarpal (TECH FIG 6G–I).

images  Live fluoroscopy is best to confirm reduction and screw lengths when there are multiple screws in different planes (TECH FIG 6J).

images

TECH FIG 6  A. Longer oblique and spiral fractures are more securely fixed with screws alone. Plate constructs must be excessively long to provide four cortices of fixation proximal and distal to the fracture site. B. A long oblique ring finger metacarpal fracture extends to the metacarpal head, but dissection distally can be kept to a minimum by using lag screws as the sole means of fixation. C.Fluoroscopy helps define the fracture anatomy, especially at the apex of the volar fragment—an area that will be hidden from direct inspection once the fracture is reduced. D. The pointed clamp secures the reduction while lag screws are placed. E. Fluoroscopy is used to confirm reduction because volar fracture lines may not be easily visible. Long oblique and spiral fractures may look well reduced dorsally while remaining displaced or malrotated. F. Ink marks the proximal extent of the fracture after two lag screws have been placed. G. Careful AO technique is followed to place a third 2.0-mm screw in the small remaining area. A 2.0-mm drill makes a glide hole through the dorsal cortex. (continued)

images

TECH FIG 6  (continued) H. A 1.5-mm drill creates the threaded hole through the volar cortex. I. A countersink disperses forces about the screw head to prevent an iatrogenic fracture of the dorsal lip of bone. J. Radiograph confirms an anatomic reduction.

OPEN REDUCTION AND INTERNAL FIXATION OF METACARPAL HEAD FRACTURES

images  Metacarpal head fractures often occur in the coronal plane (TECH FIG 7A) and may be associated with fractures of the neck or shaft.

images  Make a longitudinal or curvilinear incision over the metacarpal head (TECH FIG 7B).

images  Split the extensor mechanism and incise the capsule longitudinally (TECH FIG 7C).

images  Flex the MCP joint to facilitate exposure of the fracture (TECH FIG 7D).

images  Reduce the fracture with a dental pick or small pointed reduction forceps.

images  Insert guidewires from a cannulated headless screw set to maintain the reduction (TECH FIG 7E).

images  Insert headless screws over the guidewires (TECH FIG 7F).

images  Close the extensor mechanism with 4-0 nonabsorbable suture (TECH FIG 7G).

images  Confirm appropriate screw placement and fracture reduction radiographically (TECH FIG 7H,I).

images

TECH FIG 7  A. A volar coronal shear fracture in an adolescent boy has resulted in several millimeters of joint incongruity. B. A dorsal approach is chosen, although this fracture may also be seen well volarly. C. The extensor mechanism and capsule are incised. D. The fracture fragment is small but critical for flexion stability of the metacarpophalangeal joint. (continued)

images

TECH FIG 7  (continued) E. The fracture has been reduced with the proximal phalangeal base to restore metacarpal head congruity. Provisional fixation is achieved with two guidewires. F. Definitive fixation with cannulated headless screws facilitates early rehabilitation. G. The repaired extensor incision will tolerate active and active assisted motion immediately. H, I. AP and lateral views reveal a smooth articulation.

images

images

POSTOPERATIVE CARE

images Protective splints or casts are typically worn for 4 to 6 weeks after surgery depending on the stability of fixation, the soft tissue envelope, and treatment of associated injuries.

images The interphalangeal joints should undergo immediate active and active assisted motion to promote tendon gliding and prevent capsular contracture.

images It is also important to mobilize the MCP joint as this allows the greatest extensor excursion over the fracture site. If necessary due to swelling, comminution of the metacarpal neck, or troubles with soft tissue healing, the MCP joint may be immobilized in the safe position (flexed 70 degrees) for about 3 weeks.

images Kirschner wires are removed about 4 weeks after surgery. When callus is slow to form on radiographs and the fracture site remains tender, wires may be left in place for several more weeks if the pin sites remain free of infection.

images Bone grafting should be considered if union is not achieved by 8 to 12 weeks.

images Plates may be removed 4 to 6 months after surgery if they are causing pain or extensor tendon irritation.

OUTCOMES

images The literature provides no conclusive evidence that either of the methods of fixation of metacarpal fractures is superior.

images Surgical stabilization of a single closed extra-articular metacarpal fracture generally results in a good functional outcome. Nonoperative management of these injuries will also result in a good functional outcome, behooving the surgeon to identify an appropriate surgical indication—most commonly malrotation.

images Outcome after surgical management of multiple or open metacarpal fractures is less predictable and mostly depends on the patient's long-term digital motion. Peritendinous adhesions and capsular contracture can be minimized by even small amounts of motion during the early postoperative period.

images Nonunion is rare and usually is associated with infection, segmental bone loss, or a compromised soft tissue envelope. Occasionally, an innocuous-appearing transverse fracture may be slow to heal due to the combination of soft tissue stripping for plate fixation and the small surface area of the fracture.

COMPLICATIONS

images Malunion (flexion or rotational deformity)

images Delayed union or nonunion (more common with surgery)

images Pin site or surgical wound infection

images Extensor tendon adhesions or rupture

images MCP or interphalangeal capsular contractures

COMPLICATIONS

images Malunion (flexion or rotational deformity)

images Delayed union or nonunion (more common with surgery)

images Pin site or surgical wound infection

images Extensor tendon adhesions or rupture

images MCP or interphalangeal capsular contractures

REFERENCES

1.     Ali A, Hamman J, Mass DP. The biomechanical effects of angulated boxer's fractures. J Hand Surg Am 1999;24A:835–844.

2.     Black D, Mann RJ, Constein R, et al. Comparison of internal fixation techniques in metacarpal fractures. J Hand Surg Am 1985;10A: 466–472.

3.     Gonzalez MH, McKay W, Hall RF Jr. Low-velocity gunshot wounds of the metacarpal: treatment by early stable fixation and bone grafting. J Hand Surg Am 1993;18A:267–270.

4.     Graham TJ. The exploded hand syndrome: logical evaluation and comprehensive treatment of the severely crushed hand. J Hand Surg Am 2006;31A:1012–1023.

5.     Jahss SA. Fractures of the metacarpals: a new method of reduction and immobilization. J Bone Joint Surg Am 1938;20A:178–186.

6.     Strauch RJ, Rosenwasser MP, Lunt JG. Metacarpal shaft fractures: the effect of shortening on the extensor tendon mechanism. J Hand Surg Am 1998;23A:519–523.



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