10: Extensor Tendon Repair in Zones 1 to 5

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Procedure 10 Extensor Tendon Repair in Zones 1 to 5

Pao-Yuan Lin, Sandeep J. Sebastin, Kevin C. Chung

See Video 7: Turnover Tendon Flap for PIP Extensor Tendon Injury

Indications

Open wound with divided extensor tendon involving more than 50% of the width of the tendon

Examination/Imaging

Imaging

Radiographs of the hand should be obtained to rule out any associated foreign bodies or fractures (Fig. 10-1).

FIGURE 10-1

Surgical Anatomy

Extensor tendon injuries are divided into nine zones for the fingers and seven zones for the thumb numbered from distal to proximal (Fig. 10-2A). An easy way to remember these zones is to bear in mind that the odd-numbered zones are located over the joints. Therefore zones 1, 3, 5, and 7 are located over the distal interphalangeal (DIP) joint, proximal interphalangeal (PIP) joint, metacarpophalangeal (MCP) joint, and wrist, respectively.

The extensor tendon is thick over the MCP joint but becomes broad and thin over the dorsum of the proximal phalanx, where it divides into three portions. The central portion becomes the central slip that inserts into the base of the middle phalanx, and the lateral portions join the lateral bands. The tendons of the lumbrical and interosseous muscles form the lateral bands. These lateral bands come together over the middle phalanx and form the most distal part of the extensor tendon that inserts into the base of the distal phalanx (Fig. 10-2B).

At the MCP joint, the extensor tendon is held in position by the sagittal bands, which arise from the volar plate of the MCP joint and the intermetacarpal ligaments, to insert on the extensor hood. Injury to the sagittal bands may result in subluxation of the extensor tendon.

There is very little excursion of the extensor tendon over the fingers (11 to 17 mm at the MCP joint, 6 to 8 mm at the PIP joint, and 4 to 5 mm at the DIP joint). It is therefore important to do an accurate repair and avoid bunching up the tendon. It is usually possible to pass a core suture through the extensor tendon in the proximal half of zone 4 and in zone 5. However, only a simple suture is possible in zones 1, 2, and 3.

Lacerations to the extensor pollicis longus (EPL) tendon cannot be tested by simply examining extension of the thumb interphalangeal (IP) joint. The IP joint may be extended by the extensor pollicis brevis (EPB) and the thenar intrinsic muscles via their insertions on the extensor expansion. The EPL is tested by placing the patient’s hand flat on a table and asking the patient to lift the thumb off the table (Fig. 10-3).

FIGURE 10-2

FIGURE 10-3

Positioning

Extensor tendon repairs can be done under a digital block (zones 1, 2, and 3) or a wrist block (zones 4 and 5). The use of a forearm tourniquet (placed distally over the nonmuscular portion of the forearm) will allow the patient to tolerate the tourniquet for a longer period (30 to 40 minutes) compared with the usual placement over the arm (20 to 30 minutes). The patient is positioned supine with the affected extremity on a hand table.

Exposures

The existing lacerations are incorporated to raise wide flaps with a broad tip.

Full-thickness skin flaps are raised superficial to the paratenon.

Pitfalls

Do not raise a flap with a narrow tip. This may lead to tip necrosis and exposure of the repair.

Zone 1 Injury

Clinical Examination

Patients present with a flexed posture of the DIP joint (mallet finger) and inability to actively extend the DIP joint (Fig. 10-4).

Patients with an untreated mallet finger, especially those with a preexisting hyperextensible PIP joint, can develop a compensatory swan-neck deformity because of extensor force being directed toward the central slip and leading to hyperextension at the PIP joint.

Doyle has classified mallet finger into four types (Table 10-1).

FIGURE 10-4

Table 10-1 Classification of Mallet Finger

Procedure

Step 1

The proximal end of the tendon is mobilized for 5 to 8 mm such that the tendon ends lie close to each other with the joint in neutral position.

Step 1 Pearls

If there is a gap, a small extensor retinaculum graft can be used to bridge the defect.

If there is not enough distal terminal tendon for suturing, a bone anchor can be used. The bone anchor must be passed before the joint is pinned.

Step 2

The DIP joint is pinned in extension or slight hyperextension using a 0.045-inch K-wire (Fig. 10-5A).

FIGURE 10-5

Step 2 Pearls

Pinning the joint before tendon repair is optional. It takes the stress off the repair and is valuable in patients who cannot be relied on to wear a splint.

It may be easier to pass the K-wire retrograde by flexing the DIP joint. This will also avoid any bone anchor that has been used for repair.

Step 3

A 4-0 Ethibond horizontal mattress suture is used for tendon repair (Fig. 10-5B).

Step 4

The tourniquet is released and hemostasis secured. Skin is closed with 5-0 nylon interrupted sutures.

The K-wire may be cut short and buried under the skin.

A thermoplastic splint is also provided to immobilize the DIP joint and protect the tip of the K-wire. Additional immobilization of the PIP joint in extension may be required in patients who have an associated swan-neck deformity.

Step 4 Pearls

A type III injury with loss of overlying skin will need flap coverage. Available options include a local transposition flap or a reverse dermis cross-finger flap from the adjacent digit.

Postoperative Care and Expected Outcomes

The K-wire should be maintained for 6 weeks, after which time it is removed and the patient is started on gradual mobilization of the DIP joint. The splint is maintained for an additional 4 weeks.

Patients should be advised to continue mobilizing the PIP joint during the period of DIP joint splintage.

Seventy percent to 80% of patients with zone 1 extensor tendon injuries have an excellent (no lag) to good (<10-degree lag) outcome (Fig. 10-5C).

Zone 2 Injury

Clinical Examination

Patients usually do not develop a mallet deformity because one or both of the lateral bands are spared, and the laceration usually involves only the triangular ligament.

This injury is frequently associated with a fracture of the middle phalanx (see Fig. 10-1).

Postoperative Care and Expected Outcomes

The K-wire and/or the splint is maintained for 6 weeks. Gradual mobilization is started thereafter, with splintage for an additional 4 weeks (Fig. 10-6C).

Zone 3 Injury

Clinical Examination

Patients with an injury to the central slip (zone 3) but with intact lateral bands and triangular ligament will be able to extend the PIP joint through the lateral bands that are still dorsal to the axis of the PIP joint. However, if untreated, the triangular ligament is gradually attenuated over a period of 2 to 3 weeks, and the lateral bands sublux volar to the axis of the PIP joint. This results in the lateral bands becoming a flexor of the PIP joint. The patient will now be unable to extend the PIP joint and will present with a boutonnière deformity (flexion of the PIP joint and hyperextension of the DIP joint) (Fig. 10-7).

The Elson test is useful in diagnosing a central slip injury early (before the development of a boutonnière deformity) and in differentiating a boutonnière deformity from edema of the PIP joint or a PIP joint flexion contracture. The examiner passively flexes the PIP joint to 90 degrees over a tabletop and asks the patient to attempt active extension of the PIP joint while the examiner resists PIP joint extension. Acute rupture of the central slip results in no extension power being felt at the PIP joint and significant extension power, or hyperextension, produced at the DIP joint (Fig. 10-8).

FIGURE 10-7

FIGURE 10-8

Procedure

Step 1

The tendon ends are exposed (Fig. 10-9A).

FIGURE 10-9

Step 2

The PIP joint is pinned with a 0.045-inch K-wire.

Step 4

The tourniquet is released and hemostasis secured. Skin is closed with 5-0 nylon interrupted sutures.

A thermoplastic splint is also provided to immobilize the PIP and DIP joints.

Postoperative Care and Expected Outcomes

The K-wire and/or splint is maintained for 6 weeks. Intermittent gentle active DIP joint motion is permitted. The PIP joint is mobilized after the K-wire is removed. Gradual mobilization is started with splintage for an additional 4 weeks.

Zone 4 Injury

Clinical Examination

These are similar to zone 2 injuries and are frequently associated with an underlying fracture.

There may not be any appreciable extension lag at the PIP joint owing to the continuity of the lateral bands and intrinsic tendons.

Postoperative Care and Expected Outcomes

The splint is maintained for 4 weeks, and the patient is started on mobilization thereafter. If a core suture repair was possible, the patient can be started on mobilization earlier.

Zone 5 Injury

Clinical Examination

A human bite injury should always be suspected in an open zone 5 tendon injury. These patients present with a small puncture wound over the knuckle that is associated with extensor tendon dysfunction, pain out of proportion to the presentation (owing to underlying joint infection), and a suspicious history.

A closed rupture of the sagittal band should be suspected in patients who present with an inability to extend the finger after blunt trauma to the dorsum of the hand. This can be confirmed by passively placing the patient’s digit in extension and observing whether the patient can actively maintain the position. If the patient can maintain the position, it indicates a rupture of the sagittal band; if the patient cannot maintain the position, it indicates an extensor tendon rupture (or a nerve palsy).

The ability to extend the MCP joint does not necessarily mean that the extensor tendon is in continuity. The patient may still be able to extend the finger using the adjacent extensor tendon via the juncturae tendineae.

Procedure

Step 1

The skin flaps are mobilized to expose the divided tendon ends (Fig. 10-12A).

FIGURE 10-12

Step 1 Pearls

The joint is exposed and inspected by dividing the sagittal band and the joint capsule longitudinally on the lateral aspect of the extensor tendon when a human bite injury is suspected. A wound culture should be obtained before a thorough débridement and washout.

Step 2

The MCP joint is put in full extension with a modified Kessler repair using a 4-0 Ethibond horizontal mattress core suture (Fig. 10-12B).

Step 2 Pearls

If a human bite injury is suspected, a tendon repair should not be carried out. The wounds should be left open over a drain and a delayed primary closure considered once the infection has been cleared.

Step 3

The tourniquet is released and hemostasis secured. Skin is closed with 5-0 nylon interrupted sutures.

A splint to immobilize the wrist in slight extension and the MCP joint in full extension is provided. The PIP joint is left free.

Postoperative Care and Expected Outcomes

Patients are started on a graduated therapy protocol 1 week after repair. The splint is maintained for 4 to 6 weeks (Fig. 10-12C and D).

Newport ML, Blair WF, Steyers CMJr. Long-term results of extensor tendon repair. J Hand Surg [Am]. 1990;15:961-966.

A retrospective analysis in 62 patients with 101 digits having extensor tendon injury was conducted. Sixty percent of all fingers sustained an associated injury (fracture, dislocation, joint capsule or flexor tendon damage). Patients without associated injuries achieved 64% good/excellent results and Total Active Motion of 212 degrees. Distal zones (1 to 4) had a significantly poorer result than more proximal zones (5 to 8). (Level IV evidence)

Woo SH, Tsai TM, Kleinert HE, et al. A biomechanical comparison of four extensor tendon repair techniques in zone IV. Plast Reconstr Surg. 2005;115:1674-1681.

Twelve fresh-frozen cadaver hand-forearm units (48 fingers) were randomly assigned to four suture repair treatments: the double figure-of-eight, the double modified Kessler, the six-strand double-loop, and the modified Becker suturing techniques. The modified Becker suture technique, although not easily performed, proved to be the strongest repair, with a significantly greater resistance to 1-mm and 2-mm gap and the greatest ultimate strength on maximal loading. (Level IV evidence)

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Operative Techniques Hand and Wrist Surgery