Anterior (Transthoracic) Approach to the Thoracic Spine

The transthoracic approach to the thoracic spine offers unrivaled exposure of the anterior portions of the vertebral bodies, from T2 to T12. Nevertheless, this approach seldom is used, mainly because of its dangers. A surgeon who uses the transthoracic approach only occasionally should operate with a thoracic surgeon who is accustomed to dealing with the hazards of the area.25–27

The approach is effective in the following situations:

1.   Treatment of infections, such as tuberculosis of the thoracic vertebralbodies28

2.   Fusion of the vertebral bodies

3.   Resection of the vertebral bodies for tumor and reconstruction with bonegrafting

4.   Correction of scoliosis

5.   Correction of kyphosis

6.   Osteotomy of the spine

7.   Anterior spinal cord decompression

8.   Biopsy

Position of the Patient

Place the patient on his or her side on the operating table, stabilizing the patient with a kidney rest or sandbags. Move the hand and arm on the side to be approached above the patient’s head or onto an airplane splint (Fig. 6-89). Place a small pad in the axilla of the dependent side to avoid compression of the axillary artery and vein. Feel for a radial pulse after positioning; make sure that there is no venous obstruction in the arm. The surgeon can be positioned in front of or behind the patient.

Although the thoracic vertebrae can be approached from either side, approaching from the right side is easier because the aortic arch and aorta can be avoided.

Landmarks and Incision

Landmarks

Palpate the tip of the scapula with the patient in the lateral position. Remember that the scapula is mobile and the position of the tip will vary from patient to patient. Palpate the spines of the thoracic vertebrae. They are long and slender. Observe the inframammary crease on the anterior chest wall.

Incision

Begin the incision two fingerbreadths below the tip of the scapula and curve it forward toward the inframammary crease. Complete the incision by extending it backward and upward toward the thoracic spine, ending at a point halfway up the medial border of the scapula and halfway between the spine and the scapula. The incision usually overlies the seventh or eighth rib (Fig. 6-90).

Superficial Surgical Dissection

Divide the latissimus dorsi muscle posteriorly in line with the skin incision (Fig. 6-91). Then divide the serratus anterior muscle along the same line down to the ribs (Fig. 6-92). This allows the scapula to be elevated and muscles to be cut proximally to expose the underlying ribs (Fig. 6-93). It seldom is necessary to cut the more posterior rhomboid muscles. Because the operation is not performed in an intermuscular plane, bleeding is a problem; cutting cautery (diathermy) can be used to control it (Figs. 6-98 and 6-99).

The thoracic cavity can be reached either through an intercostal space or by resection of one or more ribs. Rib resection creates a better exposure, and the cut ribs can be used for bone grafting.

Figure 6-89 Place the patient on his or her side for the anterior transthoracic approach to the spine. On the side to be approached, move the patient’s hand and arm above his or her head.

Figure 6-90 Begin the incision two fingerbreadths below the tip of the scapula. Curve the incision forward toward the inframammary crease. Complete the incision by extending it backward and upward toward the thoracic spine. The incision usually overlies the seventh rib.

The level at which the chest is entered depends on the location of the pathology to be treated. Unless the vertebrae involved are low (between T10 and T12), use the fifth intercostal space (between the fifth and sixth ribs) for entering the chest, because the scapula easily overrides the healing site and will not cause clicking. For pathology at T10 to T12, use the sixth intercostal space, which provides better exposure of the lower vertebral bodies. During its range of motion, however, the scapula may have to jump over the callus formed at the healing site, causing a click.

To use an intercostal approach, cut down onto the rib with cutting diathermy. Cut the periosteum on the upper border of the rib and into the pleura in this line. Entering the pleura from above the ribs avoids damage to the intercostal nerve and vessels, which lie along its lower border (Fig. 6-94; see Fig. 6-93). For greater exposure, strip all muscular attachments from either the cephalad or the caudad rib (usually the fifth), using a periosteal elevator or cautery, and resect the posterior three-fourths of the rib as far posterior as necessary (Fig. 6-95).

Insert a rib spreader during either approach to hold the ribs apart; spread the ribs slowly to allow the muscles to adapt. Incising the paraspinal muscles seldom is necessary. Ensure complete hemostasis, especially in the posterior angle, before proceeding.

Deep Surgical Dissection

Ask the anesthesiologist to deflate the lung. Then, gently retract it anteriorly, using moist lap pads to protect it. Under it lies the posterior mediastinum. Incise the pleura over the lateral side of the esophagus so that the esophagus can be retracted and the anterior part of the spine reached (Fig. 6-96). The esophagus is easy to mobilize with finger dissection; retract it from the anterior surface of the spine with two Penrose drains. The intercostal vessels cross the operative field; one or more may have to be tied off (Fig. 6-97). Tying off more intercostal vessels than is necessary should be avoided, however, because the blood supply to the spinal cord from these vessels varies. Damage from ischemia may occur on rare occasions if more than two sequential intercostal vessels are ligated close to the vertebral bodies. Approaching the vertebral body from the right side obviates the need to ligate both the left and right segmental intercostal arteries. Approaching the vertebrae from the right side is safer and simpler than is trying to move the aorta itself (Fig. 6100B).

Figure 6-91 Divide the latissimus dorsi posteriorly in line with the skin incision.

Figure 6-92 Divide the serratus anterior along the line of the skin incision down to the ribs.

Figure 6-93 Elevate the scapula with the cut attached muscles proximally to expose the underlying ribs. Cut the periosteum on the upper border of the rib.

Dangers

Vessels

The intercostal vessels are vulnerable at two stages. They are damaged most often during rib resection, when they run along the undersurface of the rib; they also may be damaged during exposure to the vertebrae within the chest and must be tied off carefully before they are transected and allowed to retract (see Figs. 6-94 and 6-100A).

Lungs

About every 30 minutes, ask the anesthesiologist to expand the lungs to help prevent microatelectasis postoperatively. Before closing, make sure that the lung is expanded fully.

How to Enlarge the Approach

Local Measures

If the intercostal incision is inadequate, dissect the rib below it, resect it, and spread the rib cage further apart.

Extensile Measures

This incision cannot be extended, although it can provide good access to vertebrae from T2 to T12. In the lower part of the incision, part of the diaphragm may need to be resected to enhance the exposure. To accomplish this, remove the arcuate ligament from its origin on the transverse process of L1. Note that the risks of surgery increase in this area, because two major body cavities may be entered. Reattach the diaphragm before closing.

Figure 6-94 Enter the pleura from above the rib to avoid damage to the intercostal nerve and vessels that lie along this lower border. Insert a rib spreader to hold the ribs apart.

Figure 6-95 Resect the posterior three-fourths of the ribs as far posterior as necessary for greater exposure.

Figure 6-96 Retract the deflated lung anteriorly. Identify the esophagus over the vertebral bodies. Incise the pleura over the lateral side of the esophagus to enable it to be retracted. A: View from surgeon standing dorsal to the spine. B: Axial view of exposure with patient in the decubitus position.

Figure 6-97 Mobilize the esophagus and retract it from the anterior surface of the spine. The intercostal vessels that cross the operative field are ligated.

Figure 6-98 The superficial muscles of the posterolateral aspect of the thorax.

Figure 6-99 The superficial muscles of the posterior wall of the thorax (the trapezius, serratus anterior, latissimus dorsi, and teres major) have been resected to reveal the rib cage and the intercostal muscles.

Figure 6-100 A: The ribs and lung have been resected, as well as the posterior pleura, to reveal the esophagus, azygos vein, and intercostal arteries and nerves. Note the position of the sympathetic chain. B: A detailed view of the anterolateral aspect of the thoracic spine. It is surgically significant that the azygos vein and esophagus overlie the vertebral bodies and must be mobilized to expose them.