55: Metacarpal Shaft Fractures

Published on 19/04/2015 by admin

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Procedure 55 Metacarpal Shaft Fractures

Randy R. Bindra, Micah K. Sinclair

imageSee Video 39: Metacarpal Shaft Fractures

Indications

image Displaced fracture

image Unstable fracture pattern (long spiral oblique)

image Multiple metacarpal fractures

image Angulation greater than 15 degrees

image Rotational deformity

image Shortening with loss of normal cascade

image Open injuries

image Polytrauma patient

image Early rehabilitation in the athlete

Examination/Imaging

Clinical Examination

image Note swelling and bruising over the dorsum of the hand.

image Multiple metacarpal fractures predispose to compartment syndrome of the hand.

image Look carefully for any wounds—may indicate an open fracture.

image Look carefully for rotational deformity with fingers flexed as much as possible and compare with opposite hand.

image Ensure circulation is adequate by checking capillary refill.

image Test and document digital sensation.

image Ask patient to flex and extend the interphalangeal joints within limits of pain to confirm continuity of flexor and extensor tendons.

Imaging

image Obtain posteroanterior, oblique, and true lateral films.

image Angulation must be measured against the dorsal cortex on a true lateral view.

image Shortening is assessed by evaluating alignment of the metacarpal heads—the distal ends of the small, ring, and long fingers form a straight line.

Surgical Anatomy

image Metacarpals can be easily accessed through the dorsal approach (Fig. 55-1).

image Dorsal cutaneous nerves and veins are located in the subcutaneous plane and must be identified and preserved.

image The extensor tendons are surrounded by paratenon and can be easily separated by dividing the juncturae tendinum that interconnect them at the level of the metacarpal necks (Fig. 55-2).

image

FIGURE 55-1

image

FIGURE 55-2

Positioning

image The patient is positioned supine with the arm on a hand table.

image The surgeon is seated on the cephalad side of the table with the forearm pronated to allow access to the dorsum of the hand.

image A tourniquet is used for the procedure.

Positioning Equipment

Intraoperative imaging is critical in this procedure. The mini C-arm is draped sterilely and placed at the axillary side of the table and is brought in when needed during the case.

Exposures

image A longitudinal incision is marked along the dorsum of the metacarpal. The incision is centered over the fracture and equals the length of the plate.

image In open injuries, the open wound is incorporated in the incision and excised as needed.

image For fixation of multiple fractures, two incisions on the dorsum in the second and fourth web space will provide access to adjacent metacarpals and allow decompression of the interosseous compartments if needed. Alternatively, a transverse incision across the back of the hand may be used as an extension of a preexisting traumatic wound (Fig. 55-3).

image After spreading dissection, the extensors are exposed and retracted (Fig. 55-4).

image The periosteum at the fracture site is elevated circumferentially to allow accurate reduction and remove any interposed soft tissue.

image

FIGURE 55-3

image

FIGURE 55-4

Pearls

For plating of adjacent metacarpals, a single skin incision between the metacarpals will allow access to both fractures (Fig. 55-5).

Careful spreading dissection is necessary after skin incision to preserve subcutaneous nerves and veins.

Paratenon around the extensor tendons must be preserved to minimize postoperative tendon adhesions.

Juncturae tendinum between tendons may need to be divided to facilitate retraction of the extensor tendons.

In case of excessive comminution, periosteum around the fracture is left intact, and the implant is secured distally and proximally. Figure 55-6 shows the bridge plating technique used in a comminuted metacarpal fracture due to a gunshot wound.

image

FIGURE 55-5

image

FIGURE 55-6

Pitfalls

Injury to cutaneous nerves.

Procedure

Step 1: Principles and Methods of Fixation

image In oblique and spiral fractures, achieve provisional reduction and stabilize with a K-wire (Fig. 55-7).

image Temporary fixation of transverse fractures is not usually possible. After a trial reduction is performed, proceed with fixation of the plate to one fragment.

image Type of fixation depends on the fracture geometry.

image Transverse fractures are treated with compression plating (Fig. 55-8).

image Short oblique fractures are held with reduction forceps and stabilized with a lag screw. The fixation is then reinforced with a contoured plate without additional compression through the plate (neutralization plate). If the plane of the fracture allows insertion of the lag screw through the plate, this is preferred.

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