Surgical Preparation

Before undertaking any surgical procedure, a careful history and physical examination are essential, along with proper diagnostic imaging. For lesions that can be approached via LECA, imaging should consist of plain radiographs, MRI, and possibly CT. MRI is most useful for disc surgery and tumors, and CT is often obtained to evaluate fractures and the size and orientation of the pedicles if transpedicular instrumentation is planned for augmentation. The importance of plain radiographs in preoperative evaluation cannot be overstated because it is vitally important to understand with certainty the true number of ribs that the patient has before undertaking LECA. Overall spinal alignment is also important and best assessed with plain radiographs. In the case of tumors, consideration must be given to preoperative angiography with embolization (just before surgery, if possible) to prevent excessive blood loss.

Operative Technique

Following the induction of general anesthesia, the patient should have a Foley catheter placed and appropriate preoperative antibiotics administered. The Jackson table provides optimal padding and available positioning for LECA, and all pressure points should be checked after positioning. The patient should be safely secured to the table at all points because the bed will be rotated later in the case. For discectomy or fractures, the use of intraoperative monitoring is not essential; for deformity correction and tumor cases, such monitoring may provide an additional measure of safety. Following induction and proper positioning, the next step is appropriate fluoroscopic localization of the lesion. This is critical because the exposure provides a direct view of specific vertebrae, and extending the exposure more than one level in either direction can be difficult. It is imperative to have a clear understanding of the bony anatomy on radiograph before surgery to aid in localization. The typical anatomy of the rib and thoracic spine interface is also an important fact to keep in mind. In most patients a rib abuts disc space in the thoracic spine, and this rib typically corresponds to the caudal vertebrae at the segment.¹¹ For example, at T7, the rib typically articulates with the T6-7 disc space. This anatomy holds true down to the T10-11 space. The 11th and 12th ribs typically articulate with the corresponding vertebral bodies below the disc spaces. It is generally advisable to count ribs in the thoracic spine from above and below and to compare this count with preoperative radiographs for confirmation.

Once the location has been confirmed and marked, attention is given to planning the incision. Various shapes have been used (Fig. 51-6), but the hockey stick–type incision is generally performed. The incision should generally extend from at least one segment cranial to the pathology to one segment caudal to it, with the caudal limb angling out toward the pathologic side with attention paid to the need for approaching the dorsal elements or placing instrumentation. For procedures involving dorsal fixation and fusion, the straight midline portion of the planned incision should extend to the segments to be included in the construct. In the case of single-level discectomy without a need for dorsal exposure, a paramedian incision may be used and may be as small as 5 cm in length.

FIGURE 51-6 Two variants of the standard hockey stick–style incision for the lateral extracavitary approach.

The incision is opened down to and just through the thoacodorsal fascia so that a flap consisting of skin, subcutaneous tissue, and fascia can be retracted laterally. At this point, with the erector spinae muscles visible, the rib of interest can be palpated just lateral to the bulk of the muscle. This should be marked and confirmed again with a radiograph. Once this is done, the muscles overlying the rib can be retracted medially to expose the costovertebral junction.

After the incision is made, the approach varies little. Usually one rib should be exposed for discectomy; two ribs must be exposed to widen the field for tumor or fracture where a vertebrectomy is planned. At this point, a Doyen rib-stripping tool is used to free the rib of soft tissue and the intercostal vein, artery, and nerve complex that travels on the caudal surface of the rib. The rib is then cut approximately 10 cm from its insertion and disarticulated at the costovertebral joint (Fig. 51-7). This piece can often be removed intact and should be kept for possible use as graft. For lumbar spine pathology, the same general approach applies, with the transverse processes serving the localizing function for which the ribs are used in the thoracic spine. Careful attention must be paid to the location of the nerve roots and possibly prefixed lumbosacral plexus.

FIGURE 51-7 View provided via lateral extracavitary approach following rib and pedicle removal.

At this point, it is helpful to rotate the table 20 to 30 degrees away from the surgeon so that the vertebral body comes into view. The lateral surface of the body can be cleared with blunt dissection and bipolar cautery. With the rib removed, the intercostal nerve is followed proximally to the neural foramen, which should then be enlarged with a Kerrison rongeur. There may be a vascular bundle at the foramen, which can usually be coagulated safely. With the foramen enlarged, attention is turned to the exposed pedicle. It should be thinned with a drill and removed completely, which will allow full visualization of the lateral thecal sac and exposure of the disc space and cranial portion of the vertebral body. For vertebrectomy, the rib and pedicle caudal to the lesion can be removed as well. At this point, it is wise to reconfirm the level of interest with a radiograph.

LECA then proceeds in a logical sequence of decompression, stabilization, and fusion. If the surgery is for discectomy, the operation may proceed in a standard fashion at this point, with an anular incision followed by removal of herniated fragments. This incision can be continued through LECA until the opposite side of the thecal sac is visualized. Down-pushing curettes across the disc space may help in accomplishing this. If the goal of the surgery is vertebrectomy, the entire affected body may be removed using a combination of high-speed drill, curettes, and rongeurs. In the case of fractures, it is sometimes safer to leave a few millimeters of bone attached to the dura to prevent injury. To achieve adequate vertebrectomy and proper fusion bed preparation, the disc spaces above and below must also be cleared until the end plates of the rostral and caudal vertebrae are visible (Fig. 51-8). These can then be decorticated using the drill or curettes. After this, the graft material of choice is inserted and lateral plating applied to the upper and lower vertebral bodies. In the case of discectomy, no additional instrumentation is necessary and fusion in the absence of overt instability is unnecessary. If fusion is necessary, the removed rib pieces can be used as structural autograft or alternately taken to the back table and morselized for use with expandable cages (Fig. 51-9). If necessary, dorsal instrumentation can be used as well for further support if overt instability is noted. This instrumentation should be compressed very little to avoid loosening the ventral graft and is best placed before the addition of the interbody or other ventral graft.¹²

FIGURE 51-8 Lateral extracavitary approach following partial vertebrectomy.

FIGURE 51-9 One possible method of grafting using structural autograft following partial vertebrectomy.

The wound is then irrigated with saline, and attention should be paid to the presence of bubbles in the field, which may signal a pneumothorax. If one is suspected, careful observation of the pleural fascia should be undertaken and any visible defects repaired. The retractor holding the spinae muscles can then be removed, and the muscle bundle allowed to lie in its normal anatomic position. The fascia and skin should be closed in the standard fashion.

A chest radiograph should be taken in the recovery room to check for pneumothorax, even in the absence of frank pleural wall breech. Patients can be mobilized after recovery from anesthesia, and the average length of stay following discectomy alone is 1 day.¹² Length of stay for trauma and neoplasm is longer and often depends on the patient’s other comorbidities. The incidence of pneumothorax following LECA is about 8% (although some report a higher incidence), and infection rates are less than 2%.^12,13 Vascular and pleural injuries are rare but possible complications; subarachnoid pleural fistula has been reported but is also rare.¹⁴ Postoperative atelectasis and pneumonia are also a concern, as is ileus.^1,13,15 If roots must be sacrificed, care should be taken to divide them proximal to the dorsal root ganglion to avoid excessive pain afterward.¹⁵

LECA is a technically demanding and sometimes time-consuming procedure, but it offers an unparalleled view of vertebral and disc pathology while avoiding some of the morbidity of transabdominal or transthoracic exposure. Decompression, tumor removal, and fixation can all be accomplished via a well thought out and executed LECA, which make it an invaluable tool in spinal surgery.