1. INTRODUCTION

 

Extra-articular metacarpal fractures are the most common fractures of the hand and are usually seen in young adults. Most of them are amenable to nonoperative treatment but some require open surgery. Adequate reduction and stabilization is necessary to allow early mobilization that is essential to prevent potential complications such as oedema, joint stiffness, tenoperiosteal adhesions. Overlooking these fractures may have disastrous consequences.

 

The goal of surgical treatment is to restore proper length and alignment of the injured metacarpal.

 

Surgeons can choose the most appropriate option for each location according to the type of fracture among a wide range of fixation methods.

 

2. MECHANISM OF INJURY AND CLASSIFICATION

 

These fractures are usually due to a direct impaction force.

 

They are classified according to anatomic region to help the surgeon select the appropriate treatment option (Fig. 1).

 

 

Fig. 1 : Fracture pattern a : Transverse shaft fracture b : Oblique shaft fracture c : Spiral shaft fracture d : Metacarpal base fracture e : Metacarpal head fracture f : Comminuted fracture

3. DIAGNOSIS

 

Physical examination - When the patient is asked to close hand, the metacarpal head is depressed due to the action of interossei, and its normal prominence disappears (dropped knuckle). A rotation problem can be easily identified by finger overlapping when making the hand into a fist (Fig. 2). Another symptom is localized swelling.

Fig. 2 : Rotation problem when making a partial fist (D4 crosses over D5)

Imaging - Diagnosis is based on AP and lateral x-rays (and additionally oblique views of the hand in some cases). These two views provide all necessary information on type and location of the fracture.

 

4. SURGICAL TREATMENTS AND INDICATIONS

 

 

The goal of surgical treatment is anatomic reduction of the fracture. All long finger tips pointing to the scaphoid tubercle indicates that rotational deformity (if any) has been corrected. Restoration of metacarpal length is mandatory to maintain the transverse arch and grip strength.

 

The internal fixation procedure must be technically perfect to provide a durable anatomic reduction that will permit early active range of motion.

In summary, the amount of displacement that is acceptable in such fractures depends on the involved metacarpal bone. Setting upper limits of acceptability has allowed surgeons to define indications for nonoperative and operative treatment ^[1]:

 

• dorsal angulation less than 35° for the ring and small finger
• dorsal angulation less than 10° for the index and middle finger
• 2 mm shortening
• no metacarpal rotation (any metacarpal bone).

Postoperatively, the hand is immobilized in a thermoformed orthosis in the intrinsic plus position with the wrist in extension, MCPs in 50 degrees of flexion, and syndactyly of the long fingers past PIPs, so that the potential risk of secondary displacement is minimized. Mobilization of PIPs and DIPs can be instituted immediately for approximately 3 to 6 weeks.

 

4.1. Intramedullary pinning

Fig. 3 : Transverse fracture of the neck of the fifth metacarpal - Lateral view

Fig. 4 : Transverse fracture of the neck of the fifth metacarpal - AP view

• Indication:

• Transverse or oblique fracture of the neck of the second metacarpal with angulation of more than 15 degrees, and of the fifth metacarpal with a volar angulation of more than 35 degrees (Figs. 3, 4, 5).
• Short oblique shaft fracture (Fig. 5).
• Transverse shaft fracture (Fig. 6).

Fig. 5 : Short oblique shaft fracture of the second metacarpal

Fig. 6 : Transverse shaft fracture

• Method of fixation:

Intramedullary pinning was performed using the 1976 Foucher's technique [2,3,4] and Hacketal nailing principles. This technique uses 1.0 mm or 1.2 mm K-wires with tips bent to 20 degrees using pliers and slightly trimmed to make them blunt (Fig. 7).

Fig. 7 : 1.0 mm K-wire with a bent tip

Alternatively, break-off titanium nails with a prebent tip can be used.

 

This straightforward and minimally aggressive technique provides a very satisfactory anatomical and functional outcome.

 

• Surgical approach:

 

Patient is positioned supine on the operating table with the injured upper limb placed on a radiolucent table positioned perpendicular to the patient's body.

 

The procedure is performed under local anesthesia by nerve block, with a tourniquet placed at the upper arm.

The first step is determination of the entry point for the awl under fluoroscopic guidance (Fig. 8). This point is usually located in the distalmost wrist fold (with the wrist in dorsoulnar inclination).

 

Figure 8 : Determination of the entry point under fluoroscopic guidance

A stab incision is made on the dorsolateral aspect of the hand. In order to avoid damage to the dorsal digital branches of ulnar nerve and fifth metacarpal extensor tendons, these are carefully divided using Halstead forceps and safely retracted.

• Surgical Technique:

A Velpeau bandage or folded towel is placed under the hand to raise the hand and thus avoid interference with surgical instruments. Then, a pilot hole is made by inserting a fine awl into the posteromedial border of the involved metacarpal, perpendicular to the bone surface, as close as possible to the carpal bones. The hand is placed in radial inclination to provide easy access to the base of the fifth metacarpal. The awl is advanced a few millimeters parallel to the long axis of the metacarpal (Fig. 8).

Fig. 9 : Narrow metacarpal shaft

The hole must be large enough to accommodate two intramedullary wires. The number of wires depends on the diameter of the shaft. Difficulties may be encountered in narrow shafts than can only accommodate one single wire (Fig. 9).

Fig. 10 : The wire is advanced into the medullary canal up to the fracture site

Each wire is inserted into the medullary canal and advanced up to the fracture site pending reduction (Fig. 10).

Fig. 11 : Jahss maneuver

After the fragments have been disimpacted by applying axial traction, reduction is performed using the Jahss maneuver (Fig. 11). This maneuver involves flexion of the MCP joint to 90 degrees. Then, upward pressure is applied along the proximal phalanx while counter-pressure is applied along the dorsal aspect of the metacarpal.

 

The intramedullary wire is attached to the T-handle and slowly pushed upwards using a clockwise and counterclockwise twisting motion to facilitate penetration of the distal metacarpal epiphysis.

 

Fig. 12 : Reduction and fixation of the metacarpal fracture

The bent tip of the intramedullary wire should end up in the subchondral bone (Fig. 12).

 

Wires are divergently positioned. Impaction of the fracture site eliminates the risk of having a residual interfragmentary gap.

 

Fig. 13 : Wire end is trimmed

The trailing end of the wire is bent to 90° and cut to lie a few millimeters under the skin surface (Fig. 13).

Fig. 14 : Position of intramedullary wires - AP and lateral views

Correct position of the intramedullary wires is checked on AP and lateral image intensifier views (Fig. 14).

 

After surgery, the hand is immobilized in the intrinsic plus position with syndactyly of the operated metacarpal and adjacent finger for 3 weeks.

Fourty-five days after surgery, if sound union has been achieved, the wires can be removed.

 

 

4.2. Retrograde pinning (Kapandji technique) ^[5]

•  Indication:

This technique is indicated for the treatment of transverse thumb metacarpal base fractures.

• Method of fixation:

Fixation is achieved using two 1.5 mm precontoured intramedullary wires with bent tips.

• Surgical approach:

The first step is determination of the entry point for the awl under fluoroscopic guidance. Then, two dorsolateral stab incisions are made. In order to avoid damage to the dorsal digital branches of radial nerve, these are safely retracted using Halstead forceps.

• Surgical Technique:

Two entry holes are made with a fine awl at the epiphyseal-metaphyseal junction. A first 1.5 mm wire is attached to the T-handle and inserted into the ulnar side of the distal metaphysis of the first metacarpal. The wire is advanced toward the base of the first metacarpal to within 1 mm of the fracture line (Fig. 15).

Fig. 15: Position of the wire pending reduction

Reduction is achieved by placing the affected metacarpal in abduction position while applying counter-pressure with the thumb on the distal end of the metacarpal (Fig. 16).

Fig. 16 : Reduction maneuver

Fig. 17a : Wires are anchored in the cancellous bone of the proximal epiphysis of the first metacarpal

The tip of the first wire should be anchored in the cancellous bone of the proximal epiphysis, flush with the articular surface of the metacarpal bone. The second wire (1.5 mm diameter) is inserted into the radial side of the first metacarpal and advanced in a similar manner (Fig. 17).

Fig. 17b : Both wires are anchored in the cancellous bone of the proximal epiphysis of the first metacarpal

The trailing ends of the wires are bent to 90° and cut to lie a few millimeters under the skin surface.

 

4.3. La plate system [1,2,4,6,8]

• Indication:

- Unstable long oblique/spiral metacarpal shaft fractures (Fig. 18).

Fig. 18a : Spiral metacarpal shaft fracture

Fig. 18b : Spiral metacarpal shaft fracture

- Thumb metacarpal base fracture (Fig. 19).

Fig. 19 : Thumb metacarpal base fracture

• Method of fixation:

 

Fixation is provided by 1 mm thick malleable cuttable plates, and self-tapping cortical screws with a diameter of 1.7 mm.

 

Straight plates are used for shaft fractures and L-plates for thumb metacarpal base or shaft fractures (Figs. 20 & 21).

 

• Surgical approach:

A longitudinal incision is made parallel to the extensor muscle, centered over the metacarpal bone (Fig. 20). The Gedda-Moberg volar approach should be preferred to gain easy access to the base of the thumb (Fig. 21). Periosteal stripping at fracture site should be minimal.

Fig. 20a : Fixation of a metacarpal shaft fracture using a straight plate

Fig. 20b : Fixation of a metacarpal shaft fracture using a straight plate

Fig. 20c : Fixation of a metacarpal shaft fracture using a straight plate

Fig. 20d : Fixation of a metacarpal shaft fracture using a straight plate

Fig. 20e : Fixation of a metacarpal shaft fracture using a straight plate

• Surgical Technique:

The plate is contoured and placed on the lateral aspect of the metacarpal bone (Figs. 21 & 22) to avoid potential impingement upon the extensor muscle. Partial release of the interosseous is necessary. Reduction is maintained with a clamp. The plate is secured with two cortical screws either side of the fracture.

 

Fig. 21a : Use of an L-plate for fixation of a thumb metacarpal base or shaft fracture

Fig. 21b : Use of an L-plate for fixation of a thumb metacarpal base or shaft fracture

Fig. 21c : Use of an L-plate for fixation of a thumb metacarpal base or shaft fracture

Fig. 21c : Use of an L-plate for fixation of a thumb metacarpal base or shaft fracture

Fig. 22a : Percutaneous transverse pinning of a comminuted fracture of the fourth metacarpal base

Fig. 22b : Percutaneous transverse pinning of a comminuted fracture of the fourth metacarpal base

4.4. Percutaneous pinning [1,2,6,8]

• Indication:

Percutaneous pinning is indicated for fixation of unstable transverse fractures of the base or shaft of the second and fifth metacarpals.

• Method of fixation:

Metacarpal fracture is fixed with 1 mm or 1.2 mm K-wires.

• Surgical approach:

K-wires are inserted percutaneously, taking care to avoid damage to neurovascular pedicles, flexor and extensor tendons.

• Surgical Technique:

Wires should be inserted using a powerful but low speed driver to avoid heat necrosis of the cortical bone. Wires must not interfere with healthy joints. In order to avoid distraction of the fracture during insertion, two wires placed in a cross pattern are necessary to stabilize the fracture site and avoid creation of an axis of rotation. Their position is checked using the image intensifier. Both wires are trimmed just underneath the skin as they must be long enough to be easily removed later on.

 

4.5. Transverse pinning ^[1]

• Indication:

• Unstable fracture of the fifth metacarpal neck (or neck of other metacarpals)
• Metacarpal shaft defect (with bone grafting performed concomitantly, whenever possible, or secondarily)
• Comminuted metacarpal head, shaft or base fracture.

• Method of fixation:

Fixation is provided by two 1.2 mm or 1.5 mm K-wires.

• Surgical approach:

K-wires are inserted percutaneously or through stab incisions. Care must be taken to retract and protect sensory nerve branches throughout the procedure.

 

• Surgical Technique:

Reduction is performed using the Jahss maneuver or axial traction. Both wires are inserted using a low speed power tool in the following order:

• first wire is placed proximally to secure the injured metacarpal to the adjacent metacarpal
• second wire is placed distally (Figs. 22 & 23).

Fig. 23

In metacarpal head fractures, the distal wire should be placed at some distance from the collateral ligaments to avoid postoperative joint stiffness

 

4.6. Screws [1,2,4,6,8]

• Indication:

Long oblique/spiral metacarpal fractures.

• Method of fixation:

Fixation is provided by 1.7 mm diameter self-tapping cortical screws.

• Surgical approach:

The injured metacarpal is approached through a longitudinal incision centered over the bone shaft.

• Surgical Technique:

 

Full exposure of the fracture site is necessary to evaluate the length of the spiral. Minimal periosteal stripping is performed along the spiral. Reduction is achieved with axial traction of the finger to restore the length of the bone.

 

Anatomic reduction is mandatory as malaligned bone fragments are a source of rotation problems. Reduction is maintained with the help of two Verbrugge clamps. One must carefully check axial alignment of the finger, and the absence of rotation when making a fist. A minimum of two bone screws are used. Offset screw placement is necessary as screws must always be placed perpendicular to the fracture line. In no case should they weaken the spiral. This fixation method is highly reliable and permits early mobilization with a syndactyly device in place (Fig. 24).

 

 

Fig. 24a : Long oblique fractures fixed with bone screws

Fig. 24b : Long oblique fractures fixed with bone screws

Fig. 24c : Long oblique fractures fixed with bone screws

Fig. 24d : Long oblique fractures fixed with bone screws

4.7. External fixator [1,6,7]

• Indication:

Open, comminuted, complex, double fractures or fractures associated with bone and/or skin loss (Figs. 25 & 26).

Fig. 25a : Beaubourg external fixation device used in an open comminuted fracture of the first metacarpal

Fig. 25b : Beaubourg external fixation device used in an open comminuted fracture of the first metacarpal

Fig. 26a : Fifth metacarpal fracture with bone loss treated by external fixation

Fig. 26b : Fifth metacarpal fracture with bone loss treated by external fixation

Fig. 26c : Fifth metacarpal fracture with bone loss treated by external fixation

• Method of fixation:

Fixation is provided by a Beaubourg external fixation device consisting of 1.0 mm or 1.2 mm K-wires fixed to each other using acrylic cement (Figs. 25 & 26), by a plastic tube filled with cement, or by the Hoffmann mini fixator.

• Surgical approach:

K-wires are inserted obliquely through a dorsal incision in order to preserve joint motion.

• Surgical Technique:

The wires are interconnected using thin rods. After reduction, each connection is secured with bone cement. This permits early mobilization. The goal is to achieve alignment of the fracture site and maintain the length of the digital segment.

 

5. CONCLUSION

 

 

Metacarpal bones form the bony framework of the middle section of the hand.

 

Each type of fracture should be appropriately treated, which means : appropriate surgical approach, appropriate device, and proper positioning of the device. The goal of surgical management of metacarpal injuries is to achieve adequate reduction and perfect stability of the fracture site(s), which is essential to allow early mobilization.