Significant previous cardiopulmonary disease with limited cardiopulmonary function and associated contraindications for single-lung ventilation; acute posttraumatic lung failure; significant hemostatic disturbances.

In cases with previous operative interventions or infectious diseases of the lung and mediastinum, extensive adhesions may be encountered and present a relative contraindication for thoracoscopy.³, ⁴, ⁵, ⁶

The truncal spine lies embedded almost in the center of the thoracic and abdominal cavity which is separated from each other by the diaphragm. The domelike diaphragm is connected firmly by the margins to the sternum, ribs, and spine, and arches up into the thoracic cavity. Viewed topographically, the diaphragm attaches to the spine at the level of the first lumbar vertebra, whereas the lowest point of the thoracic cavity projects with the costophrenic sinus at the level of the lower endplate of L2. This makes it possible to place a trocar intrathoracically in the costophrenic sinus, which, after partial detachment of the diaphragm, provides access to the retroperitoneal section of the spine down to the lower endplate of L2. Another anatomic feature that must be considered for each patient is the course of the aorta which will vary from person to person. The aortic arch is located approximately at the level of T5 and the descending aorta lies closely adjacent to the left side of the thoracic spine. Usually, at the level of T8, the aorta changes its position and lies directly anterior to the spine where it remains through the thoracolumbar section of the spine.

Instruments specially designed for the endoscopic technique are used for soft tissue preparation as well as disk and bone resection. Soft reusable threaded trocars—11 mm in diameter—serve to protect the soft tissue, intercostal nerve, and vascular bundle. Such instruments are offered by several manufacturers as a set.

For ventral instrumentation, we use a constrained plate system that can be applied both for endoscopic and open procedures. For vertebral body replacement, we mostly use a distractible titanium cage with fully adaptable endplates or a Harms Cage. The latter is preferred in the setting of spondylodiscitis and is filled with cancellous bone and antibiotics.¹

The operation is performed under general anesthesia, complete relaxation, and double lumen intubation. All operations on the thoracic spine and the thoracolumbar junction are performed with the patient lying on his/her side with the ipsilateral lung collapsed. The approach side is determined using preoperative computed tomography (CT) scans and depends primarily on the position of the major and the surgical pathology (Fig. 17.2A and B). At the thoracolumbar junction, we generally prefer the left-sided approach.

Specific preparation of the patient is required on the day before surgery. Pulmonary function and breathing tests are commonly performed preoperatively to assess the patient’s vital parameters. Routine bowel preparation is commonly used to decrease intraabdominal pressure and tension on the diaphragm.

The patient is stabilized in a true lateral decubitus position with four supports at the symphysis, sacrum, and scapula, as well as with an arm rest and a special U-shaped cushion for the legs (Fig. 17.3A and B). It is also possible to use a vacuum mattress (bean bed). A radiolucent table with free access for the C-arm in both planes is mandatory.

We typically use four portals:

The location, particular of the working portal, is crucial for the endoscopic operation. For this reason, we begin by obtaining a true lateral image of the operative vertebra and use
a K-wire to mark the affected vertebral projection onto the skin of the lateral thoracic wall (Fig. 17.5). The working portal is made directly above the lesion. The trocar for the endoscope is marked cranially (thoracolumbar section) or caudally (thoracic section) to the working portal 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 to these portals.

After skin disinfection and sterile draping, single-lung ventilation is begun. To start, we always select the portal located most cranially, since the risk of injury to the liver, spleen, and diaphragm is least in this location. The approach is made using a minithoracotomy technique, providing the possibility of examining the immediate surroundings of the insertion site with the fingers before introducing the trocar. The rigid 30 degrees 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 direct endoscopic visualization.

Access to the subdiaphragmatic section of the spine down to L2 requires a 4 to 5 cm long incision and partial detachment of the diaphragm at its attachment at the spine. Access to the L1/L2 intervertebral disk can be obtained with a shorter incision of 2 to 3 cm (Fig. 17.6).

To prevent the occurrence of a postoperative diaphragmatic hernia, we prefer an incision that runs parallel to the diaphragmatic attachment. In addition, we recommend that every incision that detaches more than 2 cm of the diaphragm be sutured endoscopically to reduce the risk of a diaphragmatic hernia.

As a first step, the landmarks are identified with the image intensifier after having mobilized the psoas muscle in a ventrodorsal direction. These landmarks serve as orientation points for the surgeon and cameraman during the subsequent course of the operation. For this, we use the K-wires belonging to the implant set (e.g., MACS-II Plate System, Modular-Anterior-Construct-System, Aesculap), which are then replaced by cannulated screws with integrated clamping elements. Thus, these K-wires also define the later position of the screws, and they are placed near to the endplates between the posterior and central thirds of the vertebra (Fig. 17.7A and B).

The location of the anterior border of the vertebra and the spinal canal can be calculated from the position of the K-wires. With this information and knowledge of the anatomic structures the surgeon can create a so-called “safe working area” (Fig. 17.8).

After defining the safe working area, the next steps can be carried out.

To achieve the correct position of the K-wires in the thoracolumbar junction region, we mobilize the psoas muscle from ventrally to dorsally, thus avoiding irritation of the nerve roots of the lumbar plexus. Through positioning the K-wires close to the endplates, we both avoid injury to the segment vessels and anchor the screws in a region with higher bone density.

Following the connecting line between the K-wires, we open the pleura and expose the segment vessels using a Cobb raspatory. We mobilize these vessels subperiosteally from both sides and ligate them twice with titanium clips ventrally and dorsally, raising them slightly with a nerve hook. The vessels are dissected with the endoscopic hook scissors. The lateral aspects of the vertebral body and the disks are exposed with the raspatory.

The extent of the planned partial vertebrectomy is defined with an osteotome starting with the anterior osteotomy first using a slightly angled osteotome in order to avoid any injury to the greater vessels in front. This is followed by the posterior osteotomy using a straight osteotome. The disk spaces are opened to define the cranial and caudal borders of the vertebra. After resection of the intervertebral disk(s), the fragmented portion of the vertebra is removed carefully with a rongeur. Radical removal of non-fractured parts of the vertebral body should be avoided. If decompression of the spinal canal is necessary, the lower border of the pedicle should first be identified with a blunt hook. The base of the pedicle is then resected in a cranial direction with a Kerrison rongeur and the thecal sac can be identified. Next, the posterior fragment, which occupies the spinal canal, can be removed, pulling the fragment away from the spinal cord with a small curved curette.

For vertebral body replacement, especially in bisegmental reconstructions, a distractible cage is used. The titanium cage, we use, comes with fully adaptable endplates in order to reduce the risk of subsidence (Fig. 17.9A).

Before the vertebral replacement device is implanted, complete preparation of the implant site in the anterior/posterior dimension, as well as the depth should be verified by palpation with a probe hook and image intensifier control.

Two Langenbeck hooks are inserted into the incision for the working portals and the incision are widened slightly. The vertebral body replacement device is then gradually introduced through the chest wall into the thoracic cavity and positioned over the defect in the vertebral body with a holder. We now check once again that no soft tissue, in particular the ligated segment vessels, has slipped between the corpectomy defect and the vertebral body replacement. With carefully regulated blows on a tamp, the device is introduced into the defect. Through this process the image intensifier is used to ensure that the device is aligned well and is seated into a central position within the spine and provides appropriate distraction of the collapsed level (Fig. 17.9B). The implant is surrounded with the cancellous bone harvested from partial corpectomy. An antibiotic medium (e.g., gentamicin collagen) can be added to the cancellous bone in the setting of an infection like spondylodiscitis. After the corpectomy defect has been filled, it is covered with a fibrin fleece.

Since the screws and so-called clamping elements belonging to the implant were placed into position at the initial operative step (before beginning the partial corpectomy), the plate (e. g., MACS-II Plate System, Modular-Anterior-Construct-System, Aesculap) is able to be fastened to the ventral screws. The distance between the screws is defined with a special measuring instrument in order to select a plate of the correct length (Fig. 17.10A). This is introduced lengthways into the thoracic cavity through the incision for the working portal, laid onto the clamping elements using a holding forceps and definitively fixed with nuts which are torqued to 15 Nm.³,⁶ The plate can be brought into direct bone contact with the lateral vertebral body wall by tightening the bone screws. The ventral screws are inserted after temporary fixation of a targeting device and opening of the cortex (Fig. 17.10B). Because of the heart shape of the vertebral body, the ventral screws are usually 5 mm shorter than the dorsal screws. Insertion of a locking screw locks the polyaxial mechanism of the dorsal screws and completes the construct (Fig. 17.10C).