Thorascopic Spine Surgery

Published on 26/03/2015 by admin

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Last modified 26/03/2015

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CHAPTER 31 Thorascopic Spine Surgery

The applications of endoscopic spine surgery have been expanded since the first publications spanning nearly two decades.16 Operating techniques have been standardized and unified and today are safe procedures with low complication rates that are comparable to those of open procedures, presuming the existence of adequate training and manual skills of the surgeon.7 Thus, endoscopic operations on the spinal column no longer represent exceptional interventions but have become standard procedures in spine surgery. Thoracoscopic techniques can be used to approach the anterior column of the spine in the area between the third thoracic vertebra and the third lumbar vertebra because endoscopic splitting of the diaphragm also allows the exposure of the upper sections of the lumbar spine. The application potential includes anterior release procedures, with incision and resection of ligaments and intervertebral disks; removal of fragmented disks or sections of vertebrae, including anterior decompression of the spinal canal; replacement of vertebral bodies with biologic or alloplastic materials; and ventral stabilization procedures with implants designed for use in endoscopic spine surgery. In addition, percutaneous endoscopic techniques are used for minimally invasive treatment of degenerative disk disease of the thoracic and lumbar spine.

Technical Requirements

Instruments

image Complete sets of instruments for soft tissue and bone preparation are manufactured by contemporary instrument manufacturers (Fig. 31-2). Instruments should have a nonreflective surface and a depth scale on both sides and be ergonomically designed with big handles for safe control and handling. The technique by which they are used is called the three-point anchoring technique, which means that every sharp and potentially dangerous instrument is guided by both hands; one hand is based on the chest wall, always controlling and sometimes neutralizing unexpected forces and movements of the instrument (see Video 31-9).

Preoperative Requirements

Marking the Portals

imageAs a routine, four portals are used: scope portal, working portal, suction-irrigation portal, and retractor portal (Video 31-2). Their location and, in particular, the position of the working portal are crucial for the endoscopic operation to proceed in the optimal fashion. For this reason, the lesion is first displayed in the lateral projection (with reference to the patient’s body) under precise adjustment of the image intensifier, and a marker is used to draw the injured spinal section onto the lateral thoracic wall (Fig. 31-4). The working portal is drawn in directly above the lesion. The trocar for the endoscope is marked either caudal or cranial to the working portal, depending on the height of the lesion, and following the axis of the spine. The distance from the working portal is approximately two intercostal spaces. The entry points for suction and irrigation and for the retractor are then located ventral from these portals.

imageAfter skin disinfection and sterile draping, single-lung ventilation is begun in consultation with the anesthetist. As the first approach, the portal in the farthest cranial position is always selected because the risk of injury to the liver, spleen, and diaphragm is comparatively minor in this position. The approach is made by the mini-thoracotomy technique, providing the possibility of examining the immediate surroundings of the insertion site with the fingers before the trocar is introduced (Video 31-3). The rigid 30-degree endoscope is then carefully inserted, and the thoracic cavity is first inspected to rule out the existence of adhesions or parenchymal lesions. The other three trocars and then the instruments are subsequently introduced under endoscopic control.

Operative Techniques

Approach to the Thoracolumbar Junction

imageThis operation is also performed using single-lung ventilation (Video 31-4).8,11,15,16 Here, too, the approach side is decided by the location of the major vessels, which can be identified from the preoperative computed tomographic scan. In most cases, the best approach to the thoracolumbar junction is from the left. Placement of the trocars and instruments is illustrated in Figure 31-5.

As a first step, the affected section of the spine is drawn onto the skin of the lateral abdominal and thoracic wall under image intensifier control. Careful attention is paid to correct projection of the vertebrae, whose end plates and anterior and posterior margins should be displayed in the central beam, in sharp focus with no double contour. This marking is taken as the sole reference for subsequent placement of the portals.

The working portal is situated directly above the lesion; the portal for the endoscope is located over the spine two or three intercostal spaces away from the working portal in a cranial direction. The portals for the retractor and the suction-irrigation instrument are situated ventrally from this point.

The dome-like diaphragm is firmly connected at its margins with the sternum, ribs, and spine and arches up into the thoracic cavity. Topographically speaking, the attachment sites of the diaphragm to the spine are at the level of the first lumbar vertebra, whereas the lowest point of the thoracic cavity projects with the phrenicocostal sinus at the level of the baseplate of the second lumbar vertebra (Fig. 31-6). This makes it possible to place a trocar intrathoracically in the phrenicocostal sinus, which, after incision of the diaphragm attachment to the spine, provides access to the retroperitoneal section of the thoracolumbar junction down to the baseplate of the second lumbar vertebra. This requires a 4- to 5-cm–long incision following the attachment of the diaphragm; access to the L1-2 intervertebral disk can be obtained with a shorter incision of 2 to 3 cm (Fig. 31-7).1517

To prevent a postoperative diaphragmatic hernia, an incision that runs parallel to the diaphragmatic attachment is preferred. Because of the dome-like architecture of the diaphragm, an increase in intra-abdominal pressure from a semicircular incision parallel to the attachment causes the resected margins to come together and to adhere spontaneously, whereas a radial incision in direct proximity to the orifices of the aorta and the esophagus weakens the diaphragm fixation and causes the resected margins to gape. In addition, it is recommended that every incision in the attachment longer than 2 cm be sutured endoscopically to prevent hernia formation.

Endoscopic Treatment of Spinal Trauma (Anterior Reconstruction)

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