DEFINITION

There are a multitude of different reasons why a patient may need to undergo revision lumbar surgery. Of all patients who have an operation for degenerative lumbar disease, approximately 15% will require a

revision surgery.6

The term failed back syndrome (FBS) has been used to describe patients that experience poor clinical outcomes following lumbar surgery for degenerative causes, usually involving the intervertebral disc.8

Although this is a significant diagnosis in patients requiring lumbar revision surgery, it is not all inclusive in that it typically does not include patients with trauma, tumor, infection, or nondegenerative deformity who require reoperation.

 

 

ANATOMY

 

It is mandatory to obtain weight-bearing preoperative films to visualize the anatomy and to aid in localization. This is especially true when identifying hardware and intact bony elements as landmarks for the correct level to be operated on.

 

When reoperating on patients having had previous back surgery, spinal anatomy can be considerably distorted. In most cases, the normal bony landmarks and natural anatomic planes are often not present and may be replaced with dense fibrous scar. The dura underlying the scar can be densely adherent to it, and the surgeon can easily cause an unintended durotomy if dissection is not carried out with caution.

 

In general, the key to exposing a previously operated spine is to identify the normal anatomy and to ultimately identify the lateral wall of the bony canal which is a key landmark in identifying the neural elements. Residual bone lateral to the spinal canal (eg, the facet joints or bony fusion mass) and implanted instrumentation can also serve as valuable and reliable landmarks.

 

When reoperating on the lumbar spine, especially if hardware is in place, dissection is best started laterally by identifying the facets or hardware. From here, the surgeon can work medially to remove scar and identify dura, if necessary.

 

In patients without implanted hardware, it is safest to extend the original incision, exposing normal anatomy above and below the previous operative site. This makes it easier to identify the correct level, and dissection can proceed toward the area where the anatomy is uncertain.

 

PATHOGENESIS

 

The risk of developing a recurrent lumbar disc herniation after discectomy is approximately 5% to 18%.1,2

 

Some common causes for persistent or recurrent symptoms after lumbar surgery include failure to identify or address all of the pathology (eg, lateral recess stenosis, foraminal stenosis, or disc herniation), postoperative instability (eg, spondylolisthesis, scoliosis, kyphosis, and flat back deformity), adjacent level disease, and scar

formation.3

 

Some element of scarring occurs after all surgeries. The presence of peridural fibrosis following decompressive spinal surgery does not necessarily implicate it as a cause of the patient's symptoms, therefore. However, patients undergoing lumbar revision surgery tend to have poor outcomes when significant

fibrosis is present.4

 

Pseudarthrosis in the setting of spinal fusion surgery refers to the radiologic failure of new bone to form across the intended joint space.

 

The underlying reason why a patient may require lumbar revision surgery can be suggested by evaluating the duration of symptom relief following the initial surgery.

 

 

If the patient had no symptom relief following surgery, either the surgeon did not address the genesis of the pain or an inadequate surgical procedure was performed.

 

Transient relief of symptoms (<6 months) suggests the development of scar tissue as a cause of recurrence of symptoms.

 

If the patient experienced a long duration of relief of his or her symptoms (typically longer than 6 to 12 months), this suggests development of new pathology at either the same level or at a new level.

 

NATURAL HISTORY

 

The natural history of recurrent pathology following initial surgery is not completely known but is likely similar to that of the original condition. In other words, the natural history of a recurrent disc herniation, for example, is likely similar to that of the original herniation: spontaneous resolution of symptoms in many cases.

 

Therefore, conservative treatment should be tried before surgical intervention.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

It is important to determine that the patient has been correctly diagnosed and treated.

 

 

The three broad questions that need to be determined and asked, based on the history and physical examination, are as follows:

 

 

Was the original diagnosis correct?

 

 

Was the choice of type of surgery appropriate? Was the actual surgical technique appropriate?

 

When evaluating a patient with persistent symptoms after lumbar surgery, it is important to carefully review his or her medical and surgical history.

 

 

It is useful to categorize the patient's chief complaint into one of three groups: leg pain predominant, back pain

 

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predominant, or leg and back pain equal. This will aid the physician in determining the potential source of the patient's continuing symptoms and guide his or her medical decision making appropriately.

 

Predominant leg pain, for example, suggests a neurogenic cause for the pain.

 

Predominant back pain, on the other hand, is likely not due to a neurogenic cause and the genesis of which is much more difficult to identify.

 

A detailed history of present illness and past medical history should be obtained.

 

 

In particular, it is important to establish a surgical timeline. The onset and characteristics of initial symptoms, a detailed description of all spinal surgical interventions, and the presence or absence of symptom-free periods should be documented.

 

All medications, especially narcotic analgesics and anticoagulants, must be recorded.

 

It is important to review the patient's original presenting symptoms and compare these to the surgical procedure performed to ensure that the correct procedure was chosen.

 

In this regard, it is extremely helpful to review preoperative clinical notes and operative reports. These should be obtained whenever possible. The operative note should be scrutinized for comments about potential intraoperative adverse events such as durotomy.

 

The presence of additional factors that could affect outcome or recurrence of symptoms should be investigated.

 

 

These include the presence of a work-related injury, particularly if associated with a pending compensation claim.

 

The likelihood of secondary gain is a potentially significant factor in these patients.

 

The surgeon must also be cognizant of psychosocial issues before planning a revision operation. This includes depression and narcotic addiction.

 

 

The presence of these psychosocial factors (worker's compensation, depression, anxiety, litigation, etc.) can have a significant negative impact on patient outcome after lumbar surgery.9

 

When in doubt about potential significance of such psychosocial factors, a psychological evaluation should be obtained.

 

 

The quality and pattern of the patient's pain can provide significant information about the nature of the pain.

 

Leg pain that is described as burning, for example, suggests neuropathic pain, which is generally unresponsive to further surgical intervention.

 

Similarly, leg pain that is present constantly and is unchanged by activity generally suggests the presence of underlying changes in the nerve that are unlikely to be significantly changed by additional surgery. Such nonmechanical pain is not typical of neurogenic pain that is amenable to surgery, which is generally mechanical in nature.

 

In patients with leg pain, careful examination of the lower extremity joints and pulses is important to rule out nonspinal causes of this pain. This is particularly important in older patients in whom spinal disease frequently coexists with other degenerative conditions such as peripheral vascular disease and joint arthritis.

 

The presence of Waddell signs should also be documented, if present. One of the more significant Waddell signs is overreaction to pain. Other signs include superficial skin tenderness, regional disturbances, distraction phenomena, and simulation.

 

 

The presence of three or more Waddell signs indicates that the patient's pain is likely nonorganic and portends a poor prognosis, particularly with further surgery.10

 

Distraction testing includes the “flip test” in which a patient demonstrates a positive straight-leg raise test in the supine position but not in the seated position (FIG 1). A straight-leg raise test in a patient who is exhibiting pain behavior will be easily achieved to 90 degrees, whereas a patient with pain from a true

radiculopathy will “flip” back on their hands when attempting a sitting straight-leg raise in order to relieve tension in the sciatic nerve.7

 

With simulation, anticipatory behavior can be elicited through simulated movement. For example, the patient will report back pain through maneuvers that do not typically move the back such as mild trunk rotation through hip rotation (Table 1).

 

 

 

 

FIG 1 • Flip test. Patient should flip back on hands if straight-leg raise test is truly positive.

 

IMAGING STUDIES

 

Ideally, all of the patient's preoperative and immediate postoperative films should be reviewed. This ensures that surgically correctable pathology was initially present and that it was addressed surgically, both in terms of operating at the correct level and by doing an adequate decompression.

 

All patients being evaluated for revision lumbar surgery should have a current standing anteroposterior (AP) and lateral plain x-ray of their lumbar spine.

 

This should also include a coned-down spot lateral view of the lumbosacral level, especially in patients with prior

 

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surgery at L5-S1. This provides valuable information about sagittal and coronal alignment, hardware position and integrity, and bony anatomy.

 

Examination

Vascular

Neurogenic

 

Walking distance	Fixed	Variable
Palliative factors	Standing	Sitting/bending
Provocative factors	Walking	Walking/standing
Walking uphill	Painful	Painless
Bicycle test	Positive (painful)	Negative (painless)
Pulses	Absent	Present
Skin	Loss of hair/shiny	Normal
Back pain	Occasionally	Commonly
Back motion	Normal	Limited
Pain character	Cramping/distal to proximal	Numbness/aching/proximal to distal
Atrophy	Uncommon	Occasionally

 

Table 1 Vascular versus Neurogenic Claudication

 

 

If iatrogenic injury to the pars interarticularis is suspected, oblique views of the lumbar spine can be useful.

 

Flexion-extension lateral views of the lumbar spine can be useful to evaluate for segmental instability.

 

Most patients who have persistent back pain or leg pain after lumbar surgery will have a magnetic resonance imaging (MRI) of their lumbar spine.

 

 

In patients with a suspected recurrence of a disc herniation, it is important to make the distinction between recurrence and scar because the former is potentially amenable to surgery, whereas the latter is generally not. A precontrast and postcontrast (gadolinium) MRI is helpful to distinguish scar from recurrent disc herniation. Disc material is avascular and therefore will not enhance after gadolinium administration. Scar, on the other hand, is vascular and will therefore enhance with gadolinium.

 

In patients with older stainless steel implants, MRI is generally not useful because of significant metal

artifact that obscures detail. Under such circumstances, a combined myelogram/computed tomography (CT) scan study is useful.

 

Distortion with titanium implants is less of an issue, but in some cases, distortion from titanium implants can occur, requiring a myelogram/CT scan to identify neural compression.

 

Patients who have an implantable pacemaker or internal defibrillator or who are claustrophobic are not candidates for MRI and should have a myelogram/CT scan to visualize compressive pathology.

 

CT without myelography using coronal and sagittal reconstructions is useful to evaluate hardware placement (especially pedicle screws) and to evaluate an interbody fusion for evidence of pseudarthrosis.

 

Three-foot long AP and lateral scoliosis x-rays are sometimes useful and are mandatory to evaluate overall spinal alignment.

 

DIFFERENTIAL DIAGNOSIS

 

Wrong diagnosis

 

 

Pathology not present at time of original surgery Surgery performed for poor indications

 

 

Pathology originally present but not adequately addressed Wrong-level surgery

 

Inadequate surgery (pathology incompletely addressed)

 

New pathology

 

At same level as prior surgery

 

 

Recurrent herniated nucleus pulposus Recurrent stenosis

 

 

Arachnoiditis Epidural scar tissue

 

At different level

 

 

Herniated nucleus pulposus Stenosis

 

 

Adjacent level disease (including spondylolisthesis) Other pathology (eg, tumor)

 

 

Complications Infection

 

 

Discitis Osteomyelitis

 

 

Superficial or deep wound infection Infection associated with hardware

 

Hardware failure

 

 

Hardware breakage or loosening Hardware misplacement

Pseudarthrosis Durotomy Neural injury

Iatrogenic instability or deformity Iatrogenic flat back

Pars destabilization and resulting spondylolisthesis

Other

Noncompressive pathology

Nonspinal pathology (eg, neuropathy, hip pathology)

Psychosocial issues (including chronic pain behavior, depression, worker's compensation, or litigation) Sacroiliac disease or extraspinal joint disease

Peripheral nerve syndromes

 

 

NONOPERATIVE MANAGEMENT

 

It is advisable to try a course of conservative management, similar to that used for the index condition, for recurrent disc herniation or stenosis.

 

 

Many patients will improve with physical therapy, nonsteroidal anti-inflammatory drugs, injection therapy, or other pain management treatments.

 

Injections with a local analgesic and steroid may provide relief in patients with sacroiliac disease or other extraspinal joint disease, such as hip arthritis.

 

 

Spinal epidural injections are unpredictable in the setting of failed back surgery, although they may have a role.

 

Transforaminal injections may be useful as a diagnostic aid in localizing radicular pain to a particular nerve root.

 

Patients with multilevel degenerative disease and primary back pain refractory to other treatments may benefit from a multidisciplinary chronic pain management program. These programs typically include pain management specialists, physical therapists, physiatrists, and psychiatrists/psychologists

 

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who focus on a physical and cognitive approach to chronic back pain treatment.

 

 

Spinal cord stimulation is an option in patients with persistent and refractory back or leg pain in whom no identifiable cause for the pain can be identified.

 

SURGICAL MANAGEMENT

Preoperative Planning

 

Carefully consider the initial indication for surgery. Operating on the wrong patient or for the wrong indication is a recipe for failure.

 

Evaluation of the patient's symptoms, physical examination, and radiographic findings will help the surgeon tailor the operative plan most appropriately.

 

It is imperative that the surgeon performs a careful history and physical examination and that imaging findings are correlated with clinical findings.

 

Patients who have predominant back pain and a prior failed fusion surgery may have a pseudarthrosis or another hardware-related problem that might explain the pain.

 

Patients with leg pain as their primary complaint may have neural compression from stenosis or disc herniation.

 

It is important for the surgeon to correlate preoperative and postoperative clinical and imaging findings.

 

Positioning

 

It is generally important that the patient's abdomen be free of compression to minimize epidural bleeding. There are many options to accomplish this, and the authors prefer a Jackson table (Mizuho OSI, Union City, CA).

 

 

This table allows the abdomen to hang freely, thereby reducing intra-abdominal pressure and minimizing epidural bleeding. It also facilitates achieving lumbar lordosis (FIG 2A).

 

The kneeling position can also be used for simple revision decompressions and discectomies (FIG 2B). It is not advised for multilevel revision fusions as it produces pressure on the knees and may result in iatrogenic flat back.

 

Gardner-Wells tongs are recommended for lengthy procedures in order to avoid pressure on the globe and to reduce the likelihood of pressure or abrasions on the patient's face.

 

 

 

 

FIG 2 • A. The Jackson table allows the patient's abdomen to hang freely below the surgical field, minimizing epidural bleeding and enhancing lumbar lordosis. This position is preferred for lumbar fusion cases to preserve lumbar lordosis during instrumentation. B. The abdomen is also allowed to hang freely in the kneeling position. This position is advantageous for revision discectomies or decompressions not requiring instrumentation and fusion, as this position flattens the lumbar spine, distracting the posterior elements and facilitating approach to the disc.

 

 

Elevate the head of the bed to reduce facial edema and reduce intraocular pressure.

 

Padding of all bony prominences is advised to prevent compressive neuropathies. This included the ulnar nerve at the elbow and the lateral femoral cutaneous nerve at the level of the anterior superior iliac spine.

 

Approach

 

In general, when possible, try to avoid operating through a prior anterior or lateral exposure for revision unless absolutely necessary. The scar tissue from these procedures can make the revision approach difficult and dangerous.

 

 

If an anterior approach is absolutely required, the approach can be made from the opposite side.

 

The posterior approach is generally preferred, as this is the most familiar surgical approach for most surgeons and most pathology in patients having had prior surgery can be easily dealt with through this approach. The posterior approach gives the surgeon easy access to the pedicles in case instrumentation is needed, permits exposure of the entire lumbar and thoracolumbar spine if needed, and provides adequate access to the intervertebral discs.

 

Bleeding during revision lumbar surgery is variable. To some extent, the present of avascular scar tissue reduces the amount of bleeding. On the other hand, the amount of dissection is generally considerable, and the extent of the construct is often significant. To a large extent, the amount of bleeding is directly related to the length of the incision and the length (duration) of the surgery. In many, if not most, posterior revision cases, both are considerable.

 

 

Careful hemostasis is mandatory. This can be facilitated by the use of the Aquamantys (Medtronic, Portsmouth, NH), which is a hemostatic device that uses a combination of radiofrequency and saline to reduce blood loss.

 

Additional blood conservation can be achieved by the use of cell salvage in which intraoperative blood loss is given back to the patient.

 

Anterior or lateral procedures can be used to augment a posterior procedure in order to increase fusion rates by directly accessing the intervertebral disc. The anterior approach can be useful to treat a pseudarthrosis following a posterior

 

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fusion by providing direct access to the disc through an unoperated tissue plane. In addition, the anterior approach enables a more thorough removal of disc material and facilitates placement of a large graft to increase the likelihood of achieving fusion. This avoids the potential difficulty of trying to achieve a posterior fusion in the presence of a previously operated and scarred posterior fusion site.

 

The anterior or lateral approach may be used in unusual situations such as to address an anteriorly extruded intervertebral graft or cage.

 

The major disadvantage to the lateral and anterior approach is that they generally provide a more limited exposure to the lumbar spine than a posterior approach. They are therefore often reserved for focal revision lumbar surgery when the initial approach was posterior.

 

Minimally invasive techniques can be used for selected patients requiring lumbar revision surgery.

 

 

This may include obese patients with a recurrent disc herniation or a new herniation at a different level.

 

It is generally not advisable to perform a minimally invasive surgery in a patient requiring extensive reconstruction and instrumentation for deformity or pseudarthrosis, although exceptions do exist.

 

TECHNIQUES

Posterior Approach: Laminectomy and Discectomy

Positioning

After induction of anesthesia and intubation, the patient is positioned with the abdomen hanging freely,

 

either prone on a Jackson table or on another frame that eliminates abdominal compression such as a Wilson frame or a four-poster frame.

 

A Wilson frame offers the advantage of reducing lumbar lordosis and distracting the posterior elements, thereby facilitating the approach to the intervertebral discs.

 

Alternatively, the patient may be placed in the kneeling position.

 

For lengthy cases, it is recommended that the patient be placed on a Jackson table with the head placed in Gardner-Wells tongs with 10 pounds of traction. It is imperative that all extremities and bony prominences are carefully padded.

Exposure

 

The preoperative films should be studied to provide optimal exposure.

 

Generally, the surgeon will be going through the same incision as the previous surgery.

 

However, the normal bony landmarks may be significantly distorted or absent. In cases in which the posterior bony elements have been completely removed, the surgeon may choose to lengthen the incision proximally or distally to include adjacent normal bony landmarks as a reference.

 

It is generally safer to proceed from normal anatomy to abnormal (previously operated) levels.

 

The incision is deepened, identifying any remnants of normal anatomy that may be present such as the spinous processes, laminae, and facet joints. Care must be taken to avoid injury to the dura, which may be unprotected if a prior laminectomy has been performed.

 

In many revision surgeries, there will be significant scar tissue present, which may be firm and adherent to surrounding structures (including the dura).

 

In general, dissection should be carried out laterally along the bony wall of the canal rather than diffusely in the midline because the area of interest is the nerve root. Separation of the lateral edge of the dural sac and nerve root is facilitated by the use of either a no. 1 Penfield or a small curette.

 

Care must be taken not to carry the dissection too far laterally so as to avoid inadvertent injury to the pars. Some surgeons prefer to identify the lateral extent of the pars in order to visualize it, thereby minimizing the risk of injury to it.

 

The nerve should be followed along its entire course, including the lateral recess and neural foramen, if necessary.

Decompression

 

As with nonrevision surgery, the key to proper orientation is identifying the pedicle because the nerve passes beneath the pedicle. This is more important in revisions because other landmarks are often absent.

 

At the end of the decompression, the nerve should be relatively easily retractable medially, and a probe should be able to be passed dorsally and ventrally to the nerve root. The pedicles can be palpated with a Woodson.

Posterior Approach: Fusion and Instrumentation

Positioning

 

The patient is positioned prone on a Jackson table. Pressure points are padded and care is taken to ensure that the chest pad is not compressing breast tissue in female patients.

 

Standard Jackson table attachments (iliac and thigh pads) are used to allow maximum natural lumbar lordosis and allow the abdomen to hang freely.

Exposure

 

The presence of normal anatomy, such as preexisting spinous processes that were not removed during the previous surgery, is an excellent starting point for dissection. The amount, if any, of any such bone remaining varies depending on the type and extent of the previous surgery.

 

Because implanted hardware provides an excellent known landmark for exposure, it is generally useful to initially identify and expose laterally placed hardware.

 

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TECH FIG 1 • When performing revision exposure, the safest strategy is to proceed from normal anatomy above or below and from lateral to medial, identifying the edges of the prior laminectomy from known to unknown.

 

 

After the dissection is carried through the deep fascial layer, the dissection should be skived (angled) laterally toward the hardware rather than plunging deeply toward the unprotected dura.

 

This will bring the dissection down to the rods and screw heads.

 

Once the screw heads are exposed, the facets are easily identified (TECH FIG 1).

 

Care should be taken to avoid inadvertent injury to facet joints proximal and distal to the existing fusion unless they are to be included in an extension of the fusion. Once the hardware is visualized, the lateral

edge of the bony canal is easily identified. From here, dissection can be carried out medially.

 

Attention is first turned to separating the scar and pseudomembrane from the lateral bony canal. There is generally little to be gained by trying to remove scar from the midline dura and such attempts may lead to inadvertent durotomy.

Screw and Rob Replacement

 

Once the hardware is exposed, the next step is to remove the screws and rods. Corresponding screw widths and lengths should be recorded at each level.

 

The preexisting posterior fusion mass is then exposed, noting any evidence of pseudarthrosis.

 

Fibrous tissue within the pseudarthrosis is removed using curettes in order to preserve the intact fusion mass as much as possible.

 

Preexisting holes that contained the pedicle screws are probed to check integrity and length of the hole measured.

 

When possible, it is recommended that a slightly longer and wider diameter screw be used for the revision hardware.

 

If larger diameter screws are not available, additional augmentation may be provided by the application of polymethylmethacrylate bone cement, especially in osteoporotic patients.

 

If broken screws are encountered, several solutions are possible.

 

If the broken screw is in the middle of a construct, that level can usually be skipped, and a cross-connector can be added to provide additional stability.

 

If the broken screw is at the terminal end of a construct, the instrumentation may be extended at a level below or above the involved level, if feasible.

 

If it is thought that instrumentation at the level of the broken screw is necessary, the screw can be removed using a removal kit or by removing additional bone to expose the broken screw. The latter may necessitate additional augmentation with cement (TECH FIG 2).

 

Fusion mass may be augmented by the use of autologous iliac crest bone graft, by local bone from laminectomy if available, by graft extenders such as demineralized bone matrix, or by the off-label use of bone morphogenetic protein (BMP).

 

 

 

TECH FIG 2 • Salvage technique for saw removal.

 

 

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Transforaminal Lumbar Interbody Fusion

 

Pseudarthrosis after a posterolateral instrumented fusion is often most optimally treated by the addition of an interbody fusion through nonoperated and therefore unscarred tissue. This provides a healthy focus for fusion.

 

When a posterior approach is being used, this is most efficiently achieved through a transforaminal lumbar interbody fusion (TLIF).

 

A TLIF may not be advisable or possible in the presence of significant scar from prior surgery. But if scarring is minimal, a TLIF provides a safe and effective way to achieve additional anterior column support to facilitate fusion.

 

This is achieved by a unilateral (or if desired, bilateral) facetectomy with a pedicle-to-pedicle exposure, thereby unroofing the neural foramen entirely and allowing the root and thecal sac to be gently retracted medially.

 

The intervertebral disc is then sharply incised with a scalpel, and the disc is removed piecemeal using curettes and pituitary rongeurs.

 

The cartilaginous endplates are then removed by using a special set of dilators and scrapers.

 

Once cartilage has been removed from the bony endplates, spacers are used to estimate proper graft size. An interbody graft or synthetic cage (usually a polyetheretherketone or PEEK) is then filled with

autologous bone, allograft bone, and/or a collagen sponge soaked in BMP used in an off-label manner and placed in the disc space.

 

Placement is verified using x-ray, and the interbody graft or cage is locked into place by compressing across the previously placed pedicle screws and rods.

• Anterior Approach

   

  Anterior lumbar interbody fusion (ALIF), when feasible, provides excellent exposure to the intervertebral disc and allows the surgeon maximal access to the disc space. It is a good adjunct to a posterior fusion, especially in the presence of a pseudarthrosis after posterolateral instrumented fusion.

   

  The ALIF allows access to disc spaces that may be difficult to access posteriorly because of tenacious scar. It also allows the placement of larger grafts that can be inserted through a TLIF approach; this maximizes endplate contact with the graft and increases the chances of fusion, especially when

  combined with a posterior instrumented fusion.5

   

  A standard anterior retroperitoneal approach to the lumbar spine is used.

   

  Revision anterior procedures in patients with previous anterior lumbar surgery can be difficult and dangerous due to significant scarring. The risk of vascular injury is significant, and exposure by an experienced vascular surgeon is recommended.

• Anterolateral Retroperitoneal Approach

 

This approach is beneficial to address interbody pathology that is not otherwise accessible from a purely anterior or posterior approach.

 

The patient is placed on a standard operating room table in a right lateral decubitus position. The hip is positioned behind the table break so as to create separation between the ribcage and the iliac crest.

 

This position can treat pathology from L3 to L5. If L2 exposure is needed, it will likely be necessary to resect the 12th rib.

 

In certain circumstances, it may be advantageous to approach from the right side, but in general, avoidance of the inferior vena cava and the liver via the right lateral decubitus position is favorable.

 

The patient is secured to the table with cloth tape. The left arm is suspended in an arm sling and padded and secured to the sling with tape.

 

Fluoroscopy is used to demarcate the level of pathology. This general area is marked on the skin to plan the incision.

 

A curvilinear incision is planned beginning in front and superior to the iliac crest, curving under the 12th rib and following this rib to the insertion on the spine.

 

Once the incision is made, the subcutaneous tissue is retracted, and the first muscle that is visible will be the latissimus dorsi. This muscle is sharply divided and retracted.

 

The next layer will be the posterior inferior serratus muscle and the internal and external oblique muscles. These muscles are also divided sharply by using Bovie cautery. Care must be taken not to violate the peritoneum directly below these muscles.

 

The peritoneal layer is retracted anteriorly while the ureter and the kidney are retracted to the right, bringing into view the quadratus lumborum. The 12th rib is also identified and may be resected if higher approaches are to be attempted. The neurovascular bundle should be preserved; if this is not possible, it can be tied off and divided.

 

 

The retroperitoneal tissue overlying the lumbar spine is bluntly dissected and brought anteriorly. Care is taken to preserve the ilioinguinal and iliohypogastric nerves that will run between the

quadratus lumborum and the psoas muscle.

Once this is performed, the lateral surfaces of the lumbar vertebrae are brought into view.

 

 

PEARLS AND PITFALLS

Diagnostic ▪ Account for proper pathology

pitfalls ▪ Double check surgical indications.

• Take into account other pathology (vascular, joints, etc.)

• Back pain versus radiculopathy recurrence: Back pain is much less amenable to reoperation than radiculopathy.

Surgical

planning pitfalls

• Obtain proper imaging studies. Pre- and postgadolinium MRI should be performed

  on patients evaluated for recurrent disc pathology or stenosis. If there is a question of global imbalance or deformity, obtain standing 3-foot x-rays.

• Select correct procedure.

• Examine all old medical records.

• Ensure proper operating room tools are available (eg, a universal driver set for removing hardware).

• Prepare the iliac crest in every patient for possible use.

Surgical

technique pitfalls

• Properly position the patient. Elevate the head of the bed and ensure the abdomen

  hangs free in the prone position to minimize epidural bleeding. Use a head holder with pins if prolonged surgery is planned.

• Address neural compression.

• Pay attention to overall alignment. Standing x-rays can help the surgeon evaluate this.

• Start at the bone and work toward the unknown.

• No central scar tissue removal, stay lateral where there is bone present, and work toward the midline

• Ensure adequate lateral gutter decompression.

 

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POSTOPERATIVE CARE

 

Standard postoperative care of spine surgery patients is indicated in most patients undergoing revision surgery.

 

Pain control can be a significant issue in patients undergoing revision lumbar surgery because frequent significant preoperative narcotic requirements can make postoperative pain control difficult and because of the sheer magnitude of the surgery.

 

 

When possible, the use of an epidural pain catheter should be considered. This may not always be possible if there is significant epidural scar tissue present, making the passage of the catheter difficult.

 

Another option for pain control is patient-controlled analgesia, in which the patient controls, within certain predetermined limits, the amount of narcotic analgesic delivered.

 

If the surgery was lengthy (6 hours or more) and required significant amounts of blood products and fluids, it is usually advantageous to leave the patient intubated overnight and admitted to an intensive care unit.

 

 

The reason for prolonged postoperative intubation is often related to the amount of facial and airway swelling present. The use of the Jackson table with Gardner-Wells tongs and head of bed elevation results in a significant reduction in facial and airway edema, making it more likely that the patient can be extubated in the operating room.

 

Multilevel revision surgery or extensive front-back procedures also usually require an admission to intensive care.

 

Standard neurologic checks in the immediate postoperative period are performed to assess for neural recovery or new deficits.

 

Upright x-rays are obtained in patients with hardware placement. These are usually performed within a few days of surgery or as soon as the patient is able to comfortably stand for the x-rays.

 

OUTCOMES

Patient outcomes depend largely on initial patient diagnosis. There is a wide variety of pathology that a patient can present with after lumbar surgery, and the surgeon must carefully assess all of the information at hand to make the most informed decision.

The patient with recurrent leg pain or leg pain in a different distribution than preoperative has a good

chance of benefitting from a second operation.10 Recurrent leg pain in the same distribution as preoperative suggests reherniation of the same disc, whereas new leg pain may represent a different disc herniation.

The patient with predominant axial back pain (and normal sagittal and coronal alignment), however, will most likely not benefit from another operation. In these patients, it is very difficult for the surgeon to pinpoint the source of the back pain.

 

 

 

COMPLICATIONS

Neural injury is one of the most feared complications of revision surgery. To a large extent, the magnitude of this risk is dictated by the distortion of the normal anatomy and by the presence of scar tissue. Careful adherence to the principles outlined in this chapter will help reduce this risk.

Durotomy is a relatively common occurrence in revision lumbar surgery as the dura is often adherent to and obscured by the overlying scar and pseudomembrane.

When a durotomy is encountered, it should be repaired immediately, if possible. Failure to repair a durotomy promptly can result in the loss of thecal sac turgor and the tamponade effect that a turgid sac produces on the epidural veins. This can result in more blood loss and more difficulty with repair of the durotomy.

If the overlying scar is thick enough, it may be included in the suture line. If not, work to expose the free edges of the dura and close primarily.

A patch of muscle or fascia may be sewn under the suture line to attempt to tightly appose the defect. An absorbable hemostatic agent such as Surgicel (Ethicon, Menlo Park, CA) and/or fibrin glue may be used to cover the suture line as well.

 

Infection is always possible after revision surgery. It should be treated in the standard manner that all spine postoperative

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infections are treated: antibiotics and surgical débridement and washout if the wound is frankly purulent and draining.

With an initial infection following an instrumented fusion, it is generally recommended that the instrumentation be kept in place if it is providing stability. This requires a period of parenteral antibiotics often followed by prolonged period of oral antibiotics, with some infectious disease consultants recommending that oral antibiotics be continued indefinitely as long as the hardware is present. In general, the initial surgical débridement is accompanied by wound closure.

If a subsequent episode of infection occur, use of vacuum dressing may be required with delayed wound closure.

Pseudarthrosis may occur following an initial surgery or revision surgery. Smokers have a higher risk of pseudarthrosis than nonsmokers do. Consequently, patients should be counseled to stop smoking preoperatively. Our current practice is to mandate that patients stop smoking 3 months prior to surgery and for at least 3 months postoperatively.

 

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