9: Staged Flexor Tendon Reconstruction

Published on 18/04/2015 by admin

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Procedure 9 Staged Flexor Tendon Reconstruction

Brent M. Egeland, Sandeep J. Sebastin, Kevin C. Chung

image See Video 6: Staged Flexor Tendon Reconstruction

Indications

image Finger that is not amenable to primary or delayed primary repair or a single-stage tendon graft procedure, as in the following cases:

• Extensive crush injury with underlying unstable fracture or skin loss
• Soft tissue contractures leading to tissue deficiency (Fig. 9-1)
• Joint contractures (Fig. 9-2)
• Inadequate pulley system requiring pulley reconstruction

image Failure of previous treatment

• Late presentation of ruptured primary or delayed primary tendon repair
• Failure of single staged tendon graft

image Late presentation (>3 weeks) of a flexor digitorum profundus (FDP) avulsion injury (type 1 and type 4)

image Staged reconstruction of flexor tendons is a technically demanding procedure that should be undertaken cautiously, especially in patients with an intact flexor digitorum superficialis (FDS). Patient selection is key to the success of this procedure. Results are likely to be better in young motivated individuals with good passive range of joint motion and commitment to therapy.

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FIGURE 9-1

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FIGURE 9-2

Examination/Imaging

Clinical Examination

image The patient should be examined to identify specific tendon involvement and reconstructive needs. Patients will present with loss of active distal interphalangeal (DIP) and proximal interphalangeal (PIP) joint flexion if both the FDP and FDS are divided, or loss of only DIP joint flexion if only FDP has been injured. On inspection, the normal finger cascade is lost, with the affected digit in an extended position (see Fig. 9-2).

image The metacarpophalangeal (MCP) and interphalangeal (IP) joints should have full passive range of motion, or they will require capsulotomy before tendon reconstruction (Figs. 9-3 and 9-4).

image The patient must have adequate soft tissue cover, or soft tissue reconstruction may also be necessary.

image The patient must be examined for the presence of the palmaris longus (PL), which is the most frequently used tendon graft. Other options include plantaris, extensor indicis proprius, extensor digiti minimi, and fascia lata. The toe flexors and the proximal FDS from the injured finger are possible sources of intrasynovial tendon grafts.

• Palmaris longus: It is absent in 5% to 15% of the population. Many tests have been described for determining the presence of the PL, and we find the Mishra test easy to apply and reliable. The Mishra test is performed by holding the patient’s wrist and fingers in hyperextension while asking the patient to flex the wrist. This stretches the palmar aponeurosis and makes the PL taut when the patient attempts wrist flexion (Fig. 9-5).
• Plantaris: The absence of plantaris cannot be predicted preoperatively and has been reported in up to 6% to 20% of the population. The distal end of the plantaris is located over the deep medial aspect of the Achilles, midway between the medial malleolus and the posterior margin of the leg.
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FIGURE 9-3

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FIGURE 9-4

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FIGURE 9-5

Imaging

image Preoperative imaging studies are not typically necessary for tendon reconstruction but may be required for commonly associated injuries.

Surgical Anatomy

image The lumbrical muscle prevents further proximal retraction of the FDP tendons. For this reason, the proximal juncture of the tendon graft is usually placed in the palm to the FDP, just distal to the lumbrical origin. The median innervated first and second lumbricals are unipennate and arise from the radial and palmar surface of the FDP tendons to the index and long finger. The ulnar innervated third and fourth lumbricals are bipennate and arise from contiguous surfaces of the long/ring finger FDP tendon and ring/small finger FDP tendon, respectively. If the palm is involved in trauma, the proximal juncture is placed in the forearm.

Positioning

image The patient is placed supine on the operating table with the affected arm placed on a hand table.

image A lead hand is very useful during dissection.

image Access to the plantaris tendon may be necessary during the second stage if the palmaris is absent or a longer tendon graft is required.

Stage I: Exploration, Pulley Reconstruction, and Placement of Silicone Rod

Exposures

image Bruner incisions are designed from the mid-distal phalanx to the distal palm. Incisions are planned such that they incorporate any previous scars (Fig. 9-6).

image Thick skin flaps are raised in a plane superficial to the tendon sheath to expose the tendon sheath from the A1 pulley to the DIP joint (Fig. 9-7).

image

FIGURE 9-6

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FIGURE 9-7

Pearls

If pulley reconstruction is not necessary, two separate incisions may be used: the first for distal palm exposure and the second for exposure of the tendon sheath in the finger.

The neurovascular bundles should be identified outside the zone of injury (related to previous scars) and protected when flaps are raised, as well as for the remainder of the operation.

Procedure

Step 1: Assessment of Pulleys

image The tendon sheath is dissected carefully in an attempt to preserve any remnants of the A2 and A4 pulleys. Usually there is moderate to severe scarring, making it impossible to preserve good-quality pulleys (Fig. 9-8).

image

FIGURE 9-8

Step 2: Débridement of Scar Sheath and Tendons

image The remnants of the scarred FDS and FDP tendons are excised distal to the lumbrical origin. Approximately 1 cm of the distal FDP insertion (if available) is preserved to provide a distal anchor point for the silicone rod.

image Poor-quality scarred tendon sheath is also excised. An attempt is made to preserve remnants of the A2 and A4 pulleys on the lateral aspect of the phalanges to provide soft tissue for anchoring sutures during pulley reconstruction.

image Joint release via closed capsulotomies or direct release of tight collateral or check-rein ligaments can be performed to achieve full range of motion.

Step 2 Pearls

Excised good-quality remnants of the FDS or FDP should be saved for later use in pulley reconstruction.

Step 3: Pulley Reconstruction

image We use excised remnants of the FDS and FDP harvested from the finger or from FDS tendon in the palm or forearm to reconstruct the pulley.

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