Volar Approach to the Flexor Tendons

Volar Approach to the Flexor Tendons

The volar approach provides the best possible exposure of the flexor tendons within their fibrous sheaths.32 It also provides excellent exposure of both neurovascular bundles in the finger. The skin incision can be extended into the palm, the volar surface of the wrist, and the anterior surface of the forearm, making it a suitable approach in cases of trauma, where many levels may have to be exposed. Its other major advantage is that many skin lacerations can be incorporated into the skin incision. Its uses include the following:

1. Exploration and repair of flexor tendons

2. Exploration and repair of digital nerves and vessels

3. Exposure of the fibrous flexor sheath for drainage of pus

4. Excision of tumors within the fibrous flexor sheath

5. Excision of palmar fascia in Dupuytren contracture

 

Position of the Patient

 

Place the patient supine on the operating table with the arm abducted and lying on an arm board. Adjust the height of the table to make sitting comfortable. Most right-handed surgeons prefer to sit on the ulnar side of the affected arm. An exsanguinating bandage and tourniquet, as well as good lighting, are essential (see Fig. 5-15).

 

Landmarks and Incision

Landmarks

Three major skin creases traverse the fingers: The distal phalangeal crease, just proximal to the distal interphalangeal joint; the proximal phalangeal crease, just proximal to the proximal interphalangeal joint; and the palmar digital crease, well distal to the metacarpophalangeal joint. The course of the volar zigzag incision takes these creases into account, running diagonally across the finger between creases (Fig. 5-44).

Incision

Before the fingers are incised, mark the skin with methylene blue to outline the proposed site. The angles of the zigzag should be about 90 degrees to each other (or to the transverse skin crease); angles considerably less than 90 degrees to each other may lead to necrosis of the corners (Fig. 5-45A). The angles should not be placed too far in a dorsal direction; otherwise, the neuromuscular bundle may be damaged when the skin flaps are mobilized (see Fig. 5-45B). Of course, the basic zigzag pattern should be modified to accommodate any pre-existing lacerations (Fig. 5-46).

 

 

 

Figure 5-44 The relationship of the skin creases to the tendons and joints of the wrist and hand is seen.

 

 

Figure 5-45 A: Basic zigzag incision for exposure of the flexor tendons of the palm and fingers. B: If an incision is placed too far laterally or medially, the neurovascular bundle may be damaged.

 

 

 

Figure 5-46 The basic zigzag pattern should be adapted to pre-existing lacerations for exploration of the underlying structures. When adapting the skin incisions to previously existing lacerations, attempt to maintain an angle of about 90 degrees to prevent necrosis of the corners of the incision (inset).

 

Internervous Plane

There is no true internervous plane. The skin at the site of the incision is innervated by nerves coming from either side of the incision, so no areas of anesthesia are created.

 

Superficial Surgical Dissection

 

Reflect the skin flaps carefully with a skin hook, starting at the apex. Elevate the flaps along with some underlying fat. Do not mobilize the flaps widely until the level of the flexor sheath is reached, to ensure thick flaps and reduce the risk of skin flap necrosis (Fig. 5-47).

 

Deep Surgical Dissection

 

To expose the flexor tendons, carefully incise the subcutaneous tissues along the midline in a longitudinal fashion (Fig. 5-48). The flexor tendons lie directly underneath, within their fibrous flexor sheaths.

To expose the digital nerve and vessel, gently separate the subcutaneous tissues at the lateral border of the fibrous flexor sheath. The neurovascular bundle is separated from the volar subcutaneous flap by a thin layer of fibrous tissue known as Grayson ligament. This layer must be opened for full exposure of the neurovascular bundle. The easiest way to pry the tissues apart is to open gently a small pair of closed scissors so that the blades separate the tissues in a longitudinal plane. The blades actually are working along the line of the digital nerve, maximizing exposure of the nerve while minimizing the chance of accidental laceration (Fig. 5-49; see Fig. 5-47).

Although the approach can be deepened to expose the bone this extension is not recommended for the treatment of most bony injuries. Surgery on the osseous structures is usually safer through a midlateral or dorsal incision (Fig. 5-50). The exceptions are the repair of the volar plate of the proximal interphalangeal joint and the treatment of some fracture dislocations of the proximal interphalangeal joint. To approach the volar surface of the joint, divide the C1, A3, and C2 pulleys. Gently retract the flexor tendons using a vascular loop taking care to preserve the vinculae. The volar plate is now exposed. Ensure that the divided pulleys are reconstructed during closure (Fig. 5-51).

Incising the fibrous flexor sheath, retracting the tendons, and incising the periosteum from the volar surface of the bone lead to adhesions within the fibrous flexor sheath. It is very important to note that the consequences of this will be the loss of full function of the finger. Therefore, every effort

should be made to avoid this at all costs.

 

 

 

Figure 5-47 Elevate thick skin flaps. Stay as close to the sheath as possible to prevent damage to the laterally placed neurovascular structures.

 

 

Figure 5-48 Expose the flexor tendons in a longitudinal fashion. The digital nerves lie lateral to the tendons. Maintain the A2 and A4 pulleys.

 

 

 

Figure 5-49 Identify the neurovascular bundles and preserve them.

 

 

 

Figure 5-50 A: Incision for the midlateral approach to the finger. The incision lies between the proper digital nerve, which runs toward the palm, and its dorsal branch. The incision also can be made with the finger flexed; connect the dorsal portions of the interphalangeal creases (inset). B: Lateral view of the anatomy of the finger. Note the division of the proper (common) digital nerve into dorsal and palmar branches, the relationship of the palmar division of the nerve to the flexor tendon sheath, and the insertion of the lumbrical and interossei muscles into the hood mechanism.

 

 

Dang

 

 

Digital nerves and vessels can be damaged if the skin mobilization extends too far in a dorsal direction.

Skin flaps should not be cut at too acute an angle, and skin sutures should be meticulous to ensure closure. Skin flaps should be thick enough to avoid skin necrosis (see Fig. 5-46). The tourniquet should be removed and hemostasis secured before closure is undertaken.

 

How to Enlarge the Approach

Proximal Extension

The zigzag skin incision can be extended onto the palm, eventually joining the curved incision parallel to the thenar crease that is used for exposure of the structures of the palm, volar surface of the wrist, and anterior surface of the forearm. The key to making these incisions is to avoid crossing flexion creases at 90 degrees, thus preventing the development of flexion contractures, and to leave skin flaps with substantial corners (see Fig. 5-46).

 

 

 

Figure 5-51 The C1, A3, and C2 pulleys have been divided to allow retraction of the flexor tendons and exposure of the volar plate.