Vascularized Tendon Graft for Extensor Tendon Reconstruction

Chapter 37 Vascularized Tendon Graft for Extensor Tendon Reconstruction

Roberto Adani, MD, Luigi Tarallo, MD, Massimo Corain, MD, Jean Claude Guimberteau, MD

Outline

This chapter describes different vascularized composite tissue graft procedures incorporating tendons to reconstruct the tendons and overlying soft tissue defects in the hand. The options are the dorsalis pedis flap, the radial forearm flap, and the ulnar artery–based island flap. The radial island fasciotendinous flap is an excellent evolution of the radial forearm flap for coverage of soft tissue defects of the hand; we recommend this composite fascial flap to reconstruct the dorsum of the hand that requires simultaneous grafts of two or three tendons.

Composite tissue loss of the hand involving tendon defects represents a great clinical challenge. These injuries require restoration of both skin coverage and tendon function. These injuries are approached by different ways: multistage reconstructions of soft tissue then tendon, or single-stage vascularized composite tissue grafting.¹

Multistage reconstructions include skin coverage with distant flaps and tendon grafting in a later stage.² Nonvascularized tendon grafts in conjunction with pedicled flaps or free tissue transfer are termed partially vascularized tissue transfer.¹ Skin,³^–⁸ fascial,⁹^–¹¹ and muscle flaps^12,¹³ can be used for this purpose. A completely vascularized single-stage reconstruction uses a composite flap in which different tissue components (skin, tendon, and nerve) are included.

In 1979, Taylor and Towsend ¹⁴ described for the first time a composite free flap, with attached vascularized segments of the extensor hallucis brevis to the great toe and the extensor digitorum longus to the second toe. Subsequently, several authors¹⁵^–¹⁹ have described good results for the treatment of compound injuries with the dorsalis pedis composite flap; this flap provides four vascularized tendons (extensor digitorum communis [EDC]) of adequate length.

Reid and Moss ²⁰ modified the radial artery forearm flap to include flexor tendons from forearm. The tendons can be included are the palmaris longus (PL) and a strip of the brachioradialis tendons along with fascia and skin, and a slip of flexor carpi radialis (FCR) tendon.^21,²² The ulnar island flap of the forearm allows for the inclusion of the PL and a strip of the flexor carpi ulnaris (FCU) tendons.^23,²⁴

Operative Techniques

Dorsalis Pedis Cutaneotendinous Free Flap

The surgical procedure uses two operative teams: one to harvest the cutaneotendinous free flap and the other to prepare the recipient site. A pattern outlining the soft tissue defect on the dorsum of the hand is transferred to the dorsum of the foot centered on the second metatarsal bone using Doppler examination. It is helpful to also outline the venous drainage. Flap elevation begins distally between the first and the second toes, identifying the first dorsal metatarsal artery that is tied and sutured to the distal skin margin. The flap is elevated from distal to proximal and laterally to medially below the level of the first dorsal metatarsal artery. The flap is dissected to include in continuity, the long toe extensors to the second through fifth toes tendons, keeping the areolar tissue around the tendons, vessels, and nerves with the flap. The extensor digitorum tendons are followed proximally and are divided, according to the number of destroyed tendons in the hand. Care should be taken to preserve the paratenon on the extensor hallucis longus tendon, which is left on the foot. During elevation, the long saphenous vein or median dorsal vein is preserved, In addition, the superficial peroneal nerve must be included in the flap. Finally, the extensor retinaculum is divided and the dorsalis pedis artery can be traced until a sufficient pedicle length is obtained.

Radial Artery Forearm Island Flap With Vascularized Tendons

This is a modification of the radial artery forearm flap. Preoperatively, an Allen test must be done to ensure the presence of a complete vascular palmar arch. The presence of a PL tendon is also confirmed. The pattern of the dorsal defect is outlined around the radial vessels, and the flap is raised including skin and fascia. Two 7- to 8-cm-long strips of FCR tendon and brachioradialis tendons might be included in the flap with the PL tendon, if it is present. Care is taken to preserve the areolar tissue around the tendons, which receive their blood supply from the deep fascia. The radial artery and its venae comitantes are ligated proximally, and the flap is mobilized distally. Due to cosmetic reasons, this flap is less favored by many surgeons in recent years.

Ulnar Artery–Based Island Flap With Vascularized Tendons (Used by J.C.G.)

At the distal third of the wrist, just proximal to the flexor retinaculum, the ulnar artery on its lateral side gives off one or two branches of around 1 mm in diameter to the distal part of the FCU tendon. Two types of arterial branching can be observed, either directly from the ulnar artery or from the dorsal branch of the ulnar artery. These vascular branches are constant and easily identified on the lateral side of the pedicle. It is possible to carry out not only tendinous vascular transfers but also a cutaneotendinous transfer, and even the triple transfer of skin, tendon, and bone.

Preoperative evaluation includes the Allen test and Doppler testing to ascertain that the radial artery provides adequate blood supply to the hand. Angiography of the arm is also advisable. A bayonet-shaped incision is first traced and then made on the medial side of the forearm, the axis of the incision overlying the lateral border of the flexor carpi ulnaris (Figure 37-1). The ulnar pedicle is dissected and all its branches are carefully separated and divided.

Figure 37-1 Skin incision for harvesting the ulnar artery-based skin flap incorporating half of the FCU tendon.

First, the cutaneous branches between the ulnar artery and the skin, emerging from the volar aspect of the pedicle and which are the principal components of the ulnar forearm flap, are then carefully isolated. Then, the ulnar pedicle is separated from the ulnar nerve on its dorsal aspect along its whole length from the lower third of the forearm to Guyon’s canal. This ulnar skin flap is raised together with the FCU tendon.

The FCU tendon is longitudinally split into two parts. One is maintained in place with the muscle and the other one (i.e., the medial part) is transected at its distal insertion on the triquetrum. The proximal portion is transected at the musculotendinous junction. All the other branches of the ulnar artery are ligated, except branches to the skin flap on the anterior side and to the periosteum in the event of a bone transfer. The ulnar pedicle is dissected distally and the combined tendon–skin transfer is performed (Figure 37-2).

Figure 37-2 Ulnar artery island skin flap with the FCU tendon connecting to the flap by fascia.

The FCU and ulnar skin transfer is generally used as a retrograde flap by preserving the inflow from the distal portion of the ulnar artery. One method is by transposing to the anterior and radial side for thumb and index reconstruction. The other method is transposing to the ulnar and posterior direction. Because the transfer is oriented on the lateral side of the hand, caution has to be taken concerning the sensory branches of the radial nerve. Sutures for extensor tendon reconstruction are various, from simple sutures to Pulvertaft weaves.

Postoperative Care

We perform split-thickness skin grafting on the defect immediately following flap harvesting. When the dorsalis pedis flap is used, the ankle, foot, and toes are splinted to prevent movement under the graft. When the radial forearm flap is used, the wrist and the fingers are immobilized for 10 days with the wrist in 20° to 30° of extension with the metacarpophalangeal (MCP) joints in 50° of flexion and the interphalangeal (IP) joints in extension.⁴

Initially, the hand is splinted with the wrist at 30° of extension and MCP and IP joints in 0°. In our case series, these injuries have been managed with variable periods of immobilization after repair; nevertheless, rehabilitation of the extensor tendon has recently been settled in favor of early mobilization.²⁵

Mobilization is started after 1 week, allowing 0° to 30° movements at MCP joints with IP joints free to move during exercise. The flexion movement of MP joints is gradually increased, and after 5 weeks MCP and IP joints are left free to move during the day with night splinting. The splint is continued for 6 weeks. Patient motivation is very important: without the patient’s active participation, functional recovery could be very limited.

Outcomes

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Tags: Tendon Surgery of the Hand

Mar 5, 2016 | Posted by admin in Hand surgery | Comments Off

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