Positioning

The level of the spine being operated upon dictates positioning for thoracic and lumbar decompressive surgery. Exposure of the upper thoracic spine requires that the patient be prone with the neck moderately flexed, the arms at the side, and the shoulders depressed ( Fig. 78-1 ). Middle and lower thoracic spine exposures require that the patient be prone, with the arms either at the side or abducted at the shoulders and flexed at the elbows ( Fig. 78-2 ). For lengthy surgical procedures, we recommend that head tongs, such as Gardner-Wells tongs (Novo Surgical Inc., Oak Brook, IL), be used to allow the head to hang freely, thereby avoiding external pressure on the eyes and reducing intraocular pressure. In addition, we prefer that the head of the bed be elevated to reduce facial swelling, which can contribute to airway edema (see Fig. 78-2B ). Lumbar exposure may be performed in the prone position (see Fig. 78-2 ), kneeling position ( Fig. 78-3 ), knee-chest position, or lateral decubitus position. The important common feature of all of these positions is the absence of abdominal compression, thereby reducing intra-abdominal pressure and epidural bleeding. It is also important to limit hip and knee flexion to approximately 90 degrees or slightly greater to avoid hyperflexion of the knees, which can result in calf swelling and possible compartment syndrome ( Fig. 78-3C ). The prone and kneeling position, as compared with the lateral decubitus position, allows complete exposure of the dorsal elements from the cranium to the sacrum. It allows the surgical assistant to have a view of the surgical field equal to that of the primary surgeon and thereby facilitates surgical exposure and assistance. For these and other reasons, posterior surgeries are currently rarely done in the lateral decubitus position.

Prone position for upper thoracic laminectomy.

Note that the patient’s head is secured in three-point skeletal fixation (Mayfield tongs), and the patient is placed in reverse Trendelenburg (head up) position to reduce facial swelling. The knees are slightly flexed to relieve tension on the sciatic nerve.

A, Prone position for middle and lower thoracic laminectomy. B, Prone position on a Jackson operating table with Gardner-Wells tongs to suspend the head to reduce the risk of ocular injury and facial swelling. Note that the abdomen is hanging freely and that the head of the table is elevated in relation to the feet to further reduce the amount of facial swelling.

A, Knee-chest position on an Andrews operating table for lumbar laminectomy. B, Patient in a kneeling position using a fabricated kneeling frame. This position allows the abdomen to hang freely, thereby reducing intra-abdominal pressure and epidural venous pressure. Note that the hips and knees are flexed to only slightly more than 90 degrees. C, Patient is positioned with hips and knees hyperflexed. Note that this position promotes excessive flexion at the knees, thereby risking a compartment syndrome in the lower leg.

There are, however, potential disadvantages of the prone position. These include restriction of thoracic expansion, compression of the abdominal viscera (producing increased venous pressure in the epidural venous plexus with resulting increased bleeding with lumbar surgeries), and the potential for ocular and peripheral nerve compression. Some of these disadvantages can be obviated by use of a Jackson operating table (Mizuho OSI, Union City, CA) with Gardner-Wells skull traction, as was noted previously (see Fig. 78-2B ). This setup allows the abdomen to hang freely, thereby eliminating abdominal compression, and suspends the head, thereby eliminating the potential for ocular pressure and facial abrasions.

To position for upper thoracic procedures (T1-5), the head is placed in three-point fixation using Mayfield tongs (Integra LifeSciences Corporation, Cincinnati, OH) to provide stability to the lower cervical and upper thoracic spine (see Fig 78-1 ). Ophthalmic ointment is applied to the eyes, which are taped shut prior to prone positioning. If head tongs are not employed, plastic goggles may be utilized to minimize the risk of pressure on the eyes. Compression stockings and serial venous compression devices should be placed on the patient’s legs to reduce the likelihood of deep venous thrombosis and possible pulmonary embolus. In turning the patient to the prone position and onto the operating table, care is taken to prevent neck extension, which can cause spinal cord compression in patients with cervical stenosis. The patient is logrolled onto soft bolsters that extend from the shoulders to the pelvis, allowing the weight to be borne at these four points, allowing the chest to expand, and allowing the abdomen to be free from compression. The skeletal head holder frame is positioned so that the cervical spine is mildly flexed in a “military position” (see Fig. 78-1 ). All bony prominences, particularly the elbows, are padded, and the arms are tucked to the side. The knees are slightly flexed in order to release tension on the sciatic nerve. Exposure of the upper thoracic spine can be facilitated by using 3-inch-wide adhesive tape to depress the shoulders by extending the tape from one shoulder to the opposite side of the table distally in either a straight longitudinal or a crisscross fashion, ensuring that the adhesive tape does not obscure the operative field distally. Care must be exercised to avoid extreme shoulder depression, which can produce a traction injury to the brachial plexus. The operative table is then tilted in a mild, reverse Trendelenburg position to elevate the head in relation to the feet and to place the upper thoracic vertebrae parallel to the floor (see Figs. 78-1 and 78-2B ).

Positioning for exposure of the lower thoracic spine is identical to that for the upper thoracic spine except that the arms may be either left at the side or abducted to 90 degrees at the shoulder with the elbows flexed 90 degrees. If the arms will be abducted intraoperatively, it is important to check the patient’s shoulder motion preoperatively to be sure that the shoulders are capable of 90 degrees of abduction. In addition, care must be exercised to avoid shoulder abduction beyond 90 degrees, which can result in a painful shoulder postoperatively.

Positioning for lumbar spine exposure may be prone, in the lateral decubitus position, in a kneeling position, or in the knee-chest position. Our preference is the kneeling position on an Andrews operating table (Mizuho OSI, Union City, CA) (see Fig. 78-3A ), on a modified kneeling frame (see Fig. 78-3B ), or in the knee-chest position. These positions avoid abdominal compression, thereby reducing epidural bleeding. It is important to check preoperatively that the patient is able to flex both hips and knees to 90 degrees. This can be an issue with patients who have had prior knee surgery. For most adults, this is an excellent method of positioning for lumbar exposures. The authors have used this position without difficulty for patients in the late stages of pregnancy. The kneeling types of positioning are generally not appropriate for patients who weigh more than 300 pounds because of the risk of pressure blisters on the knees with prolonged kneeling. If the Andrews table is used, it is important to measure the chest-to-knee distance accurately before turning the patient to the prone position. As with all facedown positioning, eye protection is necessary. Venous compression stockings and alternating leg compression devices (pneumatic compression stockings) should be used, as in other spine surgeries. The patient’s feet should be padded before they are placed in the stirrups of the Andrews table. As the patient is being slid into the knee-chest position, it is important to keep sliding until the thighs are flexed to approximately 90 degrees or slightly greater. The buttocks board should be placed high on the buttocks so that it does not compress the sciatic nerves in the upper thigh. The arms are abducted 90 degrees at the shoulders, and the elbows are flexed 90 degrees, with padding of the axilla and the elbow to prevent peripheral nerve compression.