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Surgical Incisions, Positioning, and Retraction


Summary of Key Points

  • Surgical positions, incisions, and retractors are reviewed for cervical, thoracic, lumbar, and sacral operations.

  • Technical details of various surgical approaches are outlined.

  • The anatomy of ventral, dorsal, and combined approaches and how to avoid complications are discussed. Minimally invasive techniques are also outlined.

  • Ventral approaches to craniocervical junction include the transoral approach, the endoscopic transnasal approach, median labiomandibular glossotomy, the transmandibular and transthyroid approach, the ventrolateral retropharyngeal approach, and the lateral cervical approach.

  • Ventral approaches to the subaxial cervical spine include the ventromedial and ventrolateral approaches.

  • Ventral approaches to the cervicothoracic junction include the transsternal, transmanubrial, transverse supraclavicular, transclavicular, transaxillary extrapleural, lateral parascapular extrapleural, transpleural transthoracic, and trapdoor approaches.

  • Dorsal approaches to the thoracic spine are reviewed, including thoracic laminectomy, the transpedicular approach, costotransversectomy, the lateral extracavitary approach, and dorsal en bloc total spondylectomy.

  • Ventral approaches to the thoracic and thoracolumbar junction include transpleural thoracotomy, extrapleural thoracotomy, the transdiaphragmatic approach, and the ventrolateral retroperitoneal approach.

  • Ventral approaches to the lumbar and lumbosacral spine include the lateral transpsoas, pelvic brim extraperitoneal, and transperitoneal approaches.

  • Ventral approaches to the sacrum include the retroperitoneal, transperitoneal, and combined abdominosacral approaches.

A variety of ventral and dorsal incisions and approaches are used to gain access from the upper cervical to the lower sacral spine. Appropriate positioning plays an important role in minimizing blood loss and providing adequate exposure of the spine. Tissue retraction plays an equally important role. Table 80.1 presents an overview of approaches and corresponding incisions. This chapter focuses on surgical decisions, patient positioning, and retraction techniques to avoid complications during surgery.

TABLE 80.1
Classification of Surgical Approaches and Commonly Used Incision Types
Region Exposure Incision
High Cervical Spine
Dorsal approaches Suboccipital craniectomy C1–C2 laminectomy Dorsal midline
Lateral transcondylar approach Hockey-stick, retromastoid
Ventral approaches Transoral approach Midline pharynx
Median labiomandibular glossotomy Median lower lip, mandible, tongue
Transthyroidal approach Transverse below hyoid bone
Ventrolateral retropharyngeal approach T-shaped submandibular or hockey-stick
Lateral approaches Sternocleidomastoid muscle (SCM) may be cut L-shaped incision below mastoid process
Subaxial Cervical Spine (C3‒T1)
Dorsal approaches Laminoforaminotomy for cervical disc disease Dorsal paramedian
Laminectomy Dorsal midline
Laminoplasty Dorsal midline
Ventral approaches Ventromedial approach Parallel to skin crests or SCM
Ventrolateral approach––medial to the carotid artery Parallel to SCM
Ventrolateral approach––lateral to the carotid artery Parallel to SCM
Cervicothoracic Junction (C7‒T3)
Dorsal approaches Laminectomy Dorsal midline
Ventral approaches Lower ventral-medial cervical approach Parallel to SCM
Transsternal approach T-shaped; extending midsternum
Transmanubrial approach T-shaped; or parallel to SCM extending midsternum
Transverse supraclavicular approach Parallel to clavicle
Transaxillary extrapleural approach Subaxillary, parallel to T3 rib
Transpleural-transthoracic approach Parallel to T3 rib
Thoracic and Thoracolumbar Spine
Dorsal approaches Thoracic laminectomy Dorsal midline
Transpedicular approach Dorsal midline
Costotransversectomy Curved to one side paramedian
Lateral extracavitary approach Curved to one side paramedian or hockey-stick
Dorsal en bloc total spondylectomy Dorsal midline
Ventral approaches Transpleural thoracotomy Parallel to rib
Transdiaphragmatic approach Flank incision
Ventrolateral retroperitoneal approach Flank incision
Lumbar and Lumbosacral Spine
Dorsal approaches Lumbar laminectomy Dorsal midline
Paraspinal approach Paramedian
Lateral extracavitary approach Paramedian
Ventral approaches Extreme lateral interbody fusion approach or ventrolateral transpsoas approach Lateral lumbar
Pelvic brim extraperitoneal approach Lower flank incision
Transperitoneal approach Midline/horizontal subumbilical laparotomy incision
Sacrum
Dorsal approaches Dorsal approach Dorsal midline
Ventral approaches Retroperitoneal approach U-shaped suprapubic incision
Transperitoneal approach Midline subumbilical laparotomy incision

Patient Positioning

Appropriate patient positioning in the operating room is optimally determined by the combined efforts of the surgeon and the anesthesia team.

Sitting Position

An advantage of the sitting position is that it directs blood away from the surgical site. The risk of air embolism, however, is a major disadvantage. Furthermore, if the patient is quadriplegic (with a decrease in sympathetic tone), the resulting hemodynamic changes and hypoperfusion associated with the sitting position may compromise perfusion of the spinal cord. Therefore the sitting position requires a competent anesthetist, as well as right atrial and pulmonary artery catheterization, Doppler ultrasound heart monitoring, and end-tidal CO 2 monitoring.

Ventral Cervical Operations

A bolster beneath the neck and the interscapular region enhances cervical extension. Cervical distraction may be achieved by cervical traction or interbody distraction techniques.

Lateral Approaches

In the lateral decubitus position, the table may either be neutral or slightly bent to extend the rib cage. In this position, care should be taken to avoid compression of the brachial plexus; therefore, a roll should be placed under the axilla. The upper arm should be abducted no more than 90 degrees. The elbow must be properly padded ( Fig. 80.1 ).

Fig. 80.1, Lateral decubitus position is used for thoracotomy or retroperitoneal approach. A pad under the desired vertebral level and another pad under the axilla are placed. Note that the ipsilateral hip is flexed.

Retractors

Three major types of retractors are used in spine surgery: handheld retractors, patient-mounted self-retaining retractors, and table-mounted self-retaining retractors. Because intraoperative radiographs are commonly used in spine surgery, radiolucent retractors may be very helpful.

Transoral Retractors

Self-retaining retractors are usually necessary to maintain an open mouth and to depress the tongue. Self-retaining retractor rings are fixed on the upper and lower teeth. Table-mounted retractors are attached to the operating table to retract both the palate and the tongue. These retractors may also hold the neck in a fixed position; thus, they may eliminate the need for additional skeletal traction.

Ventral Cervical Retractors

Handheld retractors with blunt tips are useful for the dissection phase of the operation. For subsequent phases of ventral cervical operations, the most commonly used self-retaining retractors are the Caspar (Aesculap, Tuftlingen, Germany; Fig. 80.2 ), Apfelbaum (Aesculap; Fig. 80.3 ), Cloward (Codman, Raynham, MA), and Farley-Thompson retractors (Thompson Surgical Instruments, Traverse City, MI; Fig. 80.4 ).

Fig. 80.2, The Caspar retractor system for ventral cervical approaches (Aesculap).

Fig. 80.3, Apfelbaum self-retaining retractor for ventral odontoid screw fixation (Aesculap).

Fig. 80.4, Table-mounted retractor system of the Thompson-Farley type.

The transverse blades of self-retaining retractor systems often have teeth that should be placed under the longus colli muscles to avoid damage to the esophagus and carotid artery. The longitudinal blades are smooth.

A modified Caspar retractor has been recommended for ventrolateral foraminotomy; it enables retraction of the longus colli muscle laterally and facilitates vertebral artery retraction. Table-mounted retractors have also been used in some anterior cervical surgeries, especially during anterior odontoid screw fixation.

Ventral Thoracic and Lumbar Retractors

A crank-type retractor is useful to distract the ribs. The lungs as well as the diaphragm or retroperitoneal organs are retracted with lung and abdominal handheld retractors. Although they may narrow the operating space, the placement of laparotomy sponges under retractor blades helps to prevent damage to the viscera. The disadvantages of handheld retractors include the risk of visceral organ damage and the difficulty of manually maintaining sufficient retraction force. Table-mounted systems retract both the rib cage and the lungs.

Dorsolateral Thoracic and Lumbar Retractors

The lateral extracavitary approach to the thoracic and lumbar spine requires significant retraction. A rostral and caudal self-retaining tissue-mounted retractor may be used to medially retract the paraspinous muscles. A wide-diameter, malleable retractor can be used to laterally retract the muscles of the chest wall or the lumbodorsal muscles. Either handheld or table-mounted retractors may be used.

Tube Retractors

During the era of application of minimally invasive techniques for all kinds of surgeries, “tube retractors” have been popular for posterior spine surgeries. They were first introduced by Foley and Smith in 1997. The main advantage of this technique is dilatation of muscles and the ability to fix a tube in different angles. For discectomy and decompression of canal stenosis, 14–18-mm diameter tubes may be chosen. For screw fixation and transforaminal lumbar interbody fusion surgery, 20- to 28-mm diameter tubes are preferred. Through-tube working can be done either with an endoscope or microscope. Conventional microinstruments are used in these approaches. Most often, these specialized instruments have nonglare features.

Approaches

Dorsal Approaches to the Upper Cervical Spine

Midline Dorsal Approach

Either the sitting or the prone position can be used in a midline dorsal approach. If skull traction is required, the prone position with a horseshoe attachment should be considered.

The dorsal scalp and cervical regions are prepared for incision. If a fusion is planned, the area for the bone harvest (usually the dorsal iliac crest) should also be prepared. A midline incision is made from the external occipital protuberance to the midcervical spinous processes (C5 or C6, or the most appropriate level). Avoid unnecessary dissection, especially of the interspine and ligaments. Two deep-seated self-retaining retractors are usually satisfactory. Menezes has recommended using two retractors placed at 90 degrees to each other to prevent motion of the occipitocervical and atlantoaxial joints.

Lateral Transcondylar Approach

The lateral transcondylar approach is also termed the extreme lateral transcondylar approach or the far lateral approach. With this approach, it is possible to reach the lower clivus, the ventral foramen magnum, and the craniovertebral junction without significant retraction of the lower brain stem, the cervical spinal cord, or the cerebellum.

The sitting, lateral park-bench, or prone position may be used. In the prone position, the head should be turned to the side of the lesion (at least 20 degrees), and a rigid three-pin head holder should be used. The sitting position provides an excellent exposure, but it carries the risk of air embolism.

The lateral position is a viable option, because the cerebellum falls away from the operating site, and venous drainage is optimized. If a modified park-bench position is preferred, the head is rotated downward, flexed, and tilted away from the shoulder.

A straight dorsolateral incision may be used, although an inverted J-shaped incision is preferred. This incision begins at the mastoid process, extends rostrally and medially, and then extends caudally in the midline to the level of C6. Because the occipital muscles cover the craniectomy after the use of an inverted J-shaped incision (compared with a linear incision placed over a craniectomy), this incision is useful in preventing postoperative cerebrospinal fluid leakage.

Hooks are useful for retracting the bulky cervical musculature. A self-retaining cerebellar retractor works well.

One of the most difficult aspects of this operation is the development of a dissection plane along the lateral aspect of C1 and C2 without causing injury to the vertebral artery or associated venous structures.

To avoid the introduction of occipitocervical instability, it is recommended not to remove more than one half of the occipital condyle. The roots of C2 may be sectioned. Only a slight retraction of the vertebral artery, if any, is usually necessary. The cerebellum and the brain stem should not be retracted. Some surgeons find that removing the occipital condyle is not necessary and use the term posterolateral suboccipital retrocondylar approach. ,

Salas and colleagues have defined four varieties of dorsolateral craniocervical approaches. The transfacetal approach is used to treat extradural and intradural lesions ventral to the upper cervical spinal cord. The retrocondylar approach is performed for intradural lesions that are located predominantly lateral or ventrolateral to the spinomedullary region or to expose the extradural portion of the vertebral artery. The partial transcondylar approach is performed to treat lesions that are located predominantly ventral to the spinomedullary junction. The complete transcondylar approach is performed to treat extradural lesions. The extreme lateral transjugular approach is performed to supplement the traditional lateral transtemporal approach for the treatment of jugular foramen lesions.

Ventral Approaches to the Upper Cervical Spine

Transoral Approach

A standard placement is to have the surgeon at the side and the anesthetic equipment and anesthetist at the head of the patient. Alternatively, the anesthetic equipment may be placed at the foot, and the surgeon may be at the head of the patient. The patient is positioned supine, and intubation is performed with a small endotracheal tube, which is securely fastened. Intubation when the patent is awake may be necessary if the spine is unstable. Slight extension facilitates the approach.

Although tracheotomy is not routinely used, an elective tracheotomy should be considered if the mouth does not allow adequate space for an endotracheal tube within the operating field. Because the predominant difficulty with the transoral approach is the depth and narrowness of the operative field, a self-retaining retractor is imperative. Retraction of the uvula is also frequently necessary.

The soft palate may be held away from the surgical trajectory by a retractor or by suturing its border with the uvula to the dorsal palate. Alternatively, a rubber catheter may be passed through the nose and into the mouth. The distal tip of the catheter is sutured to the uvula, and upward traction is applied by gently pulling the catheter through the nose.

An incision is made in the midline of the dorsal pharynx after infiltration with a local anesthetic containing epinephrine to decrease oozing from the pharyngeal walls. The incision is carried along the tubercle of the atlas to the prominence of the C2‒C3 disc space. The incision may be extended, if needed, onto the soft palate and to one side of the uvula.

After dissection of the ventral surfaces of the atlas and axis laterally, a second self-retaining retractor is held to open the dorsal pharyngeal wall along the long axis of the spine. Stay sutures may be used to provide lateral retraction.

This surgery is relatively straightforward. Once the pharyngeal mucosa and prevertebral muscles have been cleared away, this approach offers an excellent view of the upper ventral cervical spine, which is relatively avascular. The primary difficulty with this approach is related to working with long instruments in a deep opening. The assistance of an endoscope may be quite useful because this can decrease the need for extensive soft-palate splitting, hard-palate resection, or extended maxillotomy. ,

Endoscopic Approach

Endoscopic or endoscopy-assisted approaches have been popular for this region. There are three main techniques. ,

  • Endoscopic transoral Approach. Transoral surgery may be done with assistance of a 30-degree endoscope. This may be considered a very useful adjunct to a microscope, not an alternative. In addition, it can be used with a wider working channel.

  • Endoscopic endonasal approach (EEA). The EEA and odontoidectomy have gained popularity. A binostril approach can be used, in which the endoscope is inserted from one nostril and the instruments from the other. Neuronavigation can help to localize the tip of the odontoid and midline structures.

    • The main advantage of a transnasal approach is to avoid transection of the palate, which would be required during a transoral operation and can cause velopharyngeal insufficiency and dysphagia. As transoral retractors are not used, tongue swelling, tooth injuries, tracheal swelling, prolonged intubation, and dysphonia are avoided. Oral feeding can be started just after surgery. In addition, using the EEA the upper limit of the inferior third of the clivus can be decompressed.

    • However, local mucosal bleeding can be quite severe, and may require nasal packing. The incidence of infection, dural tears, and vertebral artery injury is similar to that observed with classical transoral odontoidectomy.

  • Endoscopic Transcervical Approach. Assistance of an endoscope may be used during the anterolateral retropharyngeal transcervical approach.

    • The limits of these approaches are depicted in Fig. 80.5 .

      Fig. 80.5, Various endoscopic approaches and their limits which can be used for ventral decompression of the craniocervical junction.

Median Labiomandibular Glossotomy

Median labiomandibular glossotomy provides a wide ventral exposure from the clivus to the lower cervical spine. A midline vertical incision starts from the lower lip, extends caudally, turns around the chin prominence, and again passes medially in the neck. The mandible is cut in a stepwise configuration for subsequent approximation. The tongue is incised longitudinally from the central raphe, and the oropharyngeal mucosa is incised laterally.

When the mandible, mucosa, and tongue are divided, all the medial structures may be retracted laterally, and the dorsal structures, such as the epiglottis and the dorsal pharynx, are visualized.

Because of high morbidity rates, this technique is preferred mostly in cases with primary malignant or aggressive benign tumors.

Bilateral Sagittal Split Mandibular Osteotomies

This approach is performed in orthognathic surgery to repair a variety of facial and jaw deformities. Because all the incisions made in this approach are intraoral, they are not associated with the cosmetic deformities. It is an adjunct to the transoral approach, and the retraction plane is rostrocaudal instead of lateral. Lingual or inferior alveolar nerve injuries are common complications.

Transthyroid Approach

The transthyroid approach may provide access to the first four cervical vertebrae. A transverse incision is made along the upper neck crease, between the hyoid bone and the thyroid cartilage, and is extended laterally. The platysma and sternohyoid muscles are divided, and the thyrohyoid membrane is detached from the hyoid bone, while the epiglottis is protected.

The internal laryngeal nerves are protected, and the ventral pharynx is entered. Rostral retraction of the hyoid bone and caudal retraction of the thyroid cartilage are performed. After incision of the dorsal pharyngeal wall, a self-retaining retractor exposes the vertebral bodies from C1 to C4. Because of the potential for significant morbidity, this approach is used infrequently. It has been associated with damage to the superior and internal laryngeal nerves and involves a significant risk of damaging the epiglottis.

Ventrolateral Retropharyngeal Approach

The ventral retropharyngeal approach provides access to structures from the clivus to the third cervical vertebrae without entering the oral cavity. , The advantages of this approach are a lower risk of infection and more extensive exposure of the upper cervical spine.

The patient is positioned supine, and if the incision is on the right side, the head is turned to the left. Moderate extension of the head facilitates the approach to the upper cervical structures. The upper transverse portion of a T-shaped incision is made just under the mandible. The vertical portion of the incision meets the sternocleidomastoid muscle caudally. Another option is a V-shaped incision.

This ventral retropharyngeal approach may be called retrovascular or prevascular surgery ( Fig. 80.6 ). Prevascular surgery involves an access medial to the carotid sheath and traverses the same fascial planes as in the ventrolateral lower cervical spine surgery (see Fig. 80.6B ). It allows adequate spinal cord decompression up to the clivus and reconstruction of the anterior column of the spine with strut grafts and internal fixation.

Fig. 80.6, A, The ventromedial retropharyngeal approach may be accomplished by two different approaches. B, The prevascular route is taken medial to the carotid artery and internal jugular vein. C, Retrovascular surgery is performed lateral to these vascular structures.

The dissection is medial to the sternocleidomastoid muscle and the carotid artery. The submandibular gland may be resected. The facial, lingual, hypoglossal, and superior laryngeal nerves should be identified and protected. After rostral and lateral retraction of these nerves, the hyoid bone and hypopharynx may be retracted medially.

After the platysma muscle is incised, the inferior division of the facial nerve and submandibular gland may be divided. The carotid sheath is identified and protected. The dorsal belly of the digastric muscle is traced and transected near its tendon. To retract the larynx, the stylohyoid muscle is transected. The hypoglossal nerve is identified and protected. The retropharyngeal space is opened and bluntly dissected. After retraction of the longus colli muscles, a self-retaining retractor is positioned. , It may be difficult to place a self-retaining retractor in this opening. A table-mounted system may be useful in this region.

This approach may also be performed in a minimally invasive fashion with a tubular retractor placed through a window between the hypoglossal nerve and the superior laryngeal nerve.

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