55: Metacarpal Shaft Fractures

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Procedure 55 Metacarpal Shaft Fractures

Randy R. Bindra, Micah K. Sinclair

See Video 39: Metacarpal Shaft Fractures

Examination/Imaging

Clinical Examination

Note swelling and bruising over the dorsum of the hand.

Multiple metacarpal fractures predispose to compartment syndrome of the hand.

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

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

Ensure circulation is adequate by checking capillary refill.

Test and document digital sensation.

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

Imaging

Obtain posteroanterior, oblique, and true lateral films.

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

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

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

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

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).

FIGURE 55-1

FIGURE 55-2

Positioning

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

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

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

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.

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

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).

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

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

FIGURE 55-3

FIGURE 55-4

Pitfalls

Injury to cutaneous nerves.

Procedure

Step 1: Principles and Methods of Fixation

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

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

Type of fixation depends on the fracture geometry.

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

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.

For insertion of a lag screw, first drill the thread hole through both cortices. Then drill near the cortex with a lag hole and countersink near the cortex. Countersinking minimizes the risk for fracture of the near cortex when the screw is tightened by distributing force more evenly the around screw hole. Screw length is measured and the appropriate screw inserted.

Long oblique and spiral fractures that are longer than two times the diameter of the bone are stabilized with a series of lag screws. Plating is not necessary (Fig. 55-9).

When multiple lag screws are to be placed, generally the smaller fragment is lagged to the larger piece.

FIGURE 55-7

FIGURE 55-8

FIGURE 55-9

Step 1 Pearls

Initial stabilizing K-wire is helpful in fractures in which anatomic reduction is possible.

In the face of comminution, the proximal shaft fragment is stabilized with the plate first, and then the metacarpal is distracted to its correct length and rotation before fixation to the distal fragment.

Step 1 Pitfalls

In a short oblique fracture, the lag screw placement interferes with plate placement. If the fracture is in the coronal plane, the plate is fixed to bone first, and then the lag screw is passed through the plate.

Avoid aggressive countersinking of the near cortex using powered instruments to prevent weakening the cortex.

Placing a screw too close to the fracture line may result in additional comminution. Stay at least two screw head diameters away from the fracture line.

Step 2: Dynamic Compression Plate

A transverse diaphyseal fracture without comminution is best treated with compression plating.

A dynamic compression plate of adequate length is selected to ensure a minimum fixation of four cortices (two screws) on either side of the fracture.

The plate is prebent slightly so that it stands off the fracture by 2 mm to ensure that the far cortex does not gap when compression is applied.

The oval holes in the plate enable application of compression as the screws are tightened.

A trial reduction is first performed, and then the plate is fixed to one fragment with a single screw close to the fracture site. The screw is drilled and inserted in the center of the drill hole.

The plate is then aligned with the long axis of the bone, and the opposite fragment is fixed. Using an eccentric drill guide, the drill hole for the screw is made at the edge of the oval hole away from the fracture.

As the screw is inserted and centers within the plate hole, it moves the fragment closer to the fracture, thereby compressing the fracture by about 1 mm.

The remaining screws are then drilled in the center of each hole (neutral position).

Step 2 Pearls

• Ensure that the plate is aligned with the shaft before fixation.

• Use a drill guide to make all drill holes to ensure that the neutral and compression holes are drilled accurately.

• To achieve added compression, compression holes can be drilled on either side of the fracture.

Step 2 Pitfalls

Failure to prebend the plate will result in gapping at the fracture site at the opposite surface. If this situation occurs, it can be addressed with insertion of cancellous bone graft into the gap.

Inaccurate drilling of screw holes can result in distraction at the fracture when the screws are fully seated.

Axial compression with eccentric screw placement is not possible if done later in the fixation because the fragments already are fixed rigidly to the plate.

Step 3: Neutralization Plate

A neutralization plate is applied after initial fracture compression with a lag screw.

If the lag screw is to be applied through the dorsal surface of the metacarpal for a coronal fracture, the plate is applied first, and the lag screw is inserted through the plate hole.

The neutralization plate is contoured to adapt exactly to the dorsal surface of the bone. No prebending is necessary because the lag screw will prevent fracture distraction at the far cortex.

All screws must be inserted through the center of each hole to avoid inadvertent distraction at the fracture and stripping of the lag screw.

The screws farthest from the fracture are inserted first to ensure alignment of the plate with the bone.

If a lag screw is to be inserted through the plate, it is done after initial stabilization of the plate and before completion of fixation.

Step 3 Pearls

When seating the plate, position plate holes carefully—avoid leaving an empty hole alongside the fracture, which creates a weak spot for potential failure.

If a lag screw through the plate is planned, position the plate to ensure that a hole is situated at the optimal spot for lag screw insertion.

Step 3 Pitfalls

When placing a lag screw across the fracture for compression, failure to drill near the cortex with a gliding hole may result in distraction rather than compression.

Additional Steps

Transverse pinning of a metacarpal shaft fracture is an alternative treatment for fractures that can be reduced by closed manipulation (Fig. 55-10).

Fractures are usually angulated with the apex dorsal.

Reduction is achieved by closing the fingers into a fist and stabilizing the hand with all digits in corrected rotation. A dorsally directed force is applied to the flexed proximal interphalangeal joint to push the distal metacarpal fragment dorsally.

Reduction is achieved by resolution of the palpable bump and confirmed with an image intensifier.

With the surgeon holding the patient’s fingers in a closed fist with one hand, wires are introduced with the other.

A stab incision for each K-wire is made over the subcutaneous border of the metacarpal shaft (ulnar for small finger and radial border of hand for index finger), followed by blunt dissection.

Using a power driver, a K-wire is inserted transversely from the ulnar side of the small finger into the ring finger metacarpal close to the metaphalangeal joint. The wire is stopped at the ulnar cortex of the long finger metacarpal. Reduction and wire position are checked with imaging. Rotational alignment of the digit is checked again.

Two pins are inserted distal to the fracture site, and a third is inserted proximal to the fracture (Fig. 55-11).

Each K-wire should capture both cortices of the injured and neighboring uninjured metacarpal and abut against the next metacarpal shaft. The K-wire should go through four cortices and stop at the next intact one (Fig. 55-12). This will prevent late migration of the wire and ensure easy retrieval of the wires after 3 weeks.

Maintenance of reduction and pin placement are confirmed fluoroscopically.

K-wires are cut short and bent outside the skin for removal in the clinic.

FIGURE 55-10

FIGURE 55-11

FIGURE 55-12

Pearls

Attention to pain and edema control is essential in the early postoperative period.

Splinting with metacarpophalangeal joints in flexion is essential to prevent contracture.

When passing K-wire, it is important to count the number of cortices drilled to avoid incorrect trajectory of the K-wire. It should be confirmed that four cortices are passed and the K-wire stops at the outer cortex of the next intact metacarpal (fifth cortex).

Pitfalls

The tip of the K-wire, if it is not abutting the cortex of the adjacent (fifth cortex) metacarpal, may migrate.

Postoperative Care and Expected Outcomes

The hand is rested in a plaster splint for the first 5 to 7 days after surgery.

Following open reduction and plate fixation, active motion is commenced by the end of the first week after surgery. Between exercises, the injured digit and adjacent finger are immobilized in a thermoplastic splint in a functional intrinsic-plus position.

If the fracture is treated with closed reduction and percutaneous fixation, the hand is immobilized in a cast for 3 weeks, with the concern that this mode of fixation is not rigid enough to initiate active motion within 1 week. Motion is started as described previously with a protective splint thereafter. The K-wires are removed in the clinic after 3 weeks.

Most patients can be expected to regain functional motion after about 6 weeks and nearly full range of motion by 3 months.

Strengthening exercises are commenced after about 2 to 3 months when the fracture is nontender and the patient has satisfactory motion.

Pearls

Pain and edema control are essential in the immediate postoperative period.

Resting the hand with the metaphalangeal joint in flexion will prevent extension-contracture of the joint.

Pitfalls

Aggressive motion in the face of pain and swelling in the immediate postoperative period will only exacerbate symptoms and lose patient cooperation.

Fusetti C, Meyer H, Borisch N, et al. Complications of plate fixation in metacarpal fractures. J Trauma. 2002;52:535-539.

Retrospective review of 81 patients with 104 extra-articular finger metacarpal fractures treated with open reduction and plate fixation according to AO technique. Follow-up interval was an average of 13.6 months. Surgical indications included fractures that were unstable, open, multiple, or associated with multiple injuries, or additional fractures on ipsilateral extremity. Plates used included straight plates, T plates, and condylar plates. They found that 32% of fractures treated with open reduction and plating had at least one complication. Nineteen percent of patients had one or more major complications, including nonunion, stiffness, plate loosening, CPRS, and infection. Sixteen percent of patients had one or more minor complications. None could be correlated with the type of plate or fracture morphology. All were correctable. (Level V evidence)

Omokawa S, Fujitani R, Dohi Y, et al. Prospective outcomes of comminuted periarticular metacarpal and phalangeal fractures treated using a titanium plate system. J Hand Surg [Am]. 2008;33:857-863.

This is a prospective study with 51 patients with isolated comminuted metaphyseal, metacarpal, or phalangeal fractures and a 1-year follow-up period. Open fractures were included in this study. Twelve patients with metacarpal fractures achieved 91% of total active motion (TAM). Decreased TAM had significant correlation to patient age and intra-articular fracture. Grip strength was 87% of the contralateral uninjured side postoperatively. All fractures went on to union. Plates were removed from 30 patients owing to discomfort, joint stiffness, infection, and hardware breakage. (Level IV evidence)

Ouellette EA, Freeland AE. Use of the minicondylar plate in metacarpal and phalangeal fractures. Clin Orthop Relat Res. 1996;327:38-46.

Retrospective review of the treatment of 68 total fractures, 41 of which were metacarpal fractures: 12 proximal fractures, 12 shaft fractures, and 17 distal fractures. Open fractures were included in this study. Follow-up period was an average of 17 months. Range of motion was excellent in 52% and good/fair in 51% of the metacarpal fractures. All fractures went on to union, the infection rate was low (12% of all patients, including phalangeal fractures), and most complications were minor. (Level V evidence)

Page SM, Stern PJ. Complications and range of motion following plate fixation of metacarpal and phalangeal fractures. J Hand Surg [Am]. 1998;23:827-832.

Retrospective review of open reduction and internal fixation of metacarpal and/or phalangeal fractures over an 8-year period that included 66 metacarpal fractures. Surgical indications used for plate fixation included multiple fractures, open fractures with soft tissue damage, unstable fractures, bone loss, and malalignment. Thirty-six percent of patients with metacarpal fractures experienced complications, half of which were major, which included four cases of extensor lag/stiffness greater than 35 degrees and five cases of major contracture greater than 35 degrees. Plate fixation yielded a total active motion of greater than 220 degrees in 76% of fractures. Higher complication rates were associated with open fractures, periarticular fractures, and use of minicondylar plates. (Level V evidence)

Soeur JS, Mudgal CS. Plate fixation in closed ipsilateral multiple metacarpal fractures. J Hand Surg [Br]. 2008;33:740-744.

Retrospective review of 19 patients with 43 displaced and/or angulated multiple metacarpal fractures treated by early open reduction and internal fixation with 2-mm plates. Eighteen patients recovered full range of motion within 2 months of surgery; 1 patient was lost to follow-up. Implant removal was performed in two metacarpals in 2 patients, owing to extensor tenosynovitis or inhibited adjacent joint range of motion, resulting in complete resolution of symptoms. (Level V evidence)

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