Failed Back Surgery Syndrome: Diagnostic Evaluation

Richard D. Guyer, MD Abstract Michael Patterson, MD Failed back surgery syndrome is a common problem with Donna D. Ohnmeiss, DrMed enormous costs to patients, insurers, and society. The etiology of failed back surgery can be poor patient selection, incorrect diagnosis, suboptimal selection of surgery, poor technique, failure to achieve surgical goals, and/or recurrent pathology. Successful intervention in this difficult patient population requires a detailed history, precise physical examination, and carefully chosen diagnostic tests. The diagnostic evaluation should endeavor to accurately identify symptoms, rule out extraspinal causes, identify a specific spinal etiology, and assess the psychological state of the patient. Only after these factors have been assessed can further treatment be planned.

Dr. Guyer is President, Texas Back ailed back surgery syndrome Etiology of Failed Back Institute, and Co-Director, Spine Surgery F(FBSS) is a common condition Fellowship Program, Texas Back Surgery that may arise from several identifi- Institute, Plano, TX. Dr. Patterson is able causes related to the initial sur- The several common identifiable Spine Surgeon, Southern Bone and gery, including poor patient selec- causes of failure of back surgery to Joint Specialists, Hattiesburg, MS. Dr. tion, mismatch of the procedure reduce preoperative symptoms in- Ohnmeiss is President, Texas Back with patient pathology, unrealistic clude poor patient selection, incor- Institute Research Foundation, Texas Back Institute. expectations, failure of the proce- rect diagnosis, wrong procedure, dure to achieve its goals (eg, union), poor technique, failure to achieve None of the following authors or the and iatrogenic complications. FBSS surgical goals, and progressive dis- departments with which they are may also arise from new sources of ease (Table 1). Some overlap exists in affiliated has received anything of value pain that may or may not be related these categories. In some patients, from or owns stock in a commercial to the initial surgery. determination of the cause of ongo- company or institution related directly or Some of the more common types ing complaints or a new symptom indirectly to the subject of this article: of FBSS present as unresolved symp- that arises after surgery may be dif- Dr. Guyer, Dr. Patterson, and Dr. toms or new onset of symptoms fol- ficult. Familiarity with the potential Ohnmeiss. lowing lumbar diskectomy, spinal sources of symptoms in the patient Reprint requests: Dr. Guyer, Texas Back stenosis decompression, or fusion. with failed back surgery can help di- Institute, 6020 West Parker Road, Suite The initial step is to attempt to re- rect appropriate diagnostic evalua- 200, Plano, TX 75093. solve the patient’s symptomatology tion and treatment. In assessing the and to meticulously reassess the pa- patient with FBSS, making a correct J Am Acad Orthop Surg 2006;14: tient. Appropriate history, physical diagnosis is of critical importance 534-543 examination, and radiographic and before initiating further treatment. Copyright 2006 by the American neurodiagnostic evaluation may de- Further surgery based on incomplete Academy of Orthopaedic Surgeons. lineate a potential source and guide or inaccurate diagnosis will com- treatment selection. pound the patient’s problem.

534 Journal of the American Academy of Orthopaedic Surgeons Richard D. Guyer, MD, et al

Table 1 Figure 1 Etiology of Failed Back Surgery

Poor patient selection Abnormal psychometrics Chronic pain behavior Unreachable expectations Incorrect diagnosis Wrong procedure Wrong level Missed spinal stenosis Poor technique Battered root syndrome Iatrogenic instability Residual deformity Failure to achieve goal of surgery Pseudarthrosis Incomplete decompression Incomplete correction of deformity Axial T1-weighted magnetic resonance image demonstrating a conjoined left L5 Progressive disease root (left arrow) and right S1 root (right arrow). Recurrent disk herniation or spinal stenosis Transition syndrome ed that their quantitative analysis of after the index operation. Failure to psychological factors is predictive of diagnose and address foraminal or Poor Patient Selection spine surgery outcome in 82% of pa- lateral recess stenosis in a patient The most common cause of failed tients. with central stenosis is not uncom- back surgery is likely poor patient mon and may result in continued selection, which may be related to Incorrect or Incomplete radicular pain. intrinsic psychological factors. Sev- Diagnosis eral studies have reported that psy- A potential cause of a poor out- Wrong Surgical Procedure chological disturbances that are come is a misdiagnosed or over- The most common type of error documented on the Minnesota looked element of intraspinal pa- in spinal surgery is wrong-level dis- Multiphasic Personality Inventory thology. The pain may be incorrectly kectomy. Failure to correctly identi- (MMPI) can be related to poor out- attributed to radiologic evidence of fy the level of stenosis or incorporat- comes after spine surgery.1-3 The degenerative or age-related changes, ing the wrong levels in a fusion most predictive components are ele- such as disk herniation, spondyloly- are other examples of error. The vation of hysteria, hypochondriasis, sis, or spondylolisthesis, which may Joint Accreditation Commission on and depression scales. Poor results be asymptomatic. The physician Healthcare Organizations mandates are more frequent in patients who must carefully correlate patient that all institutions have a program exhibit abnormal pain behavior, symptoms with the physical exami- to prevent wrong-site surgery. The have clinical depression or nation and imaging studies. When North American Spine Society has anxiety,4-6 or receive worker’s com- these are discordant, the chance of an accepted paradigm for correct site pensation or are involved in failure is markedly increased. For in- spine surgery that includes using in- litigation.7-9 The influence and ex- stance, failure to diagnose a painful traoperative radiologic localization tent of impact of each of these fac- degenerated segment (a transitional in almost all cases.11 tors on outcome is poorly under- segment) above or below an area to Another example of incorrect pro- stood, however. To help predict be fused will result in continued cedure is selecting an operation that outcomes, a comprehensive evalua- pain following surgery. Missed diag- inadequately addresses all of the pa- tion incorporating a variety of med- nosis of a conjoined nerve root (Fig- tient’s symptomatic pathology. De- ical and psychosocial risk factors has ure 1) or far lateral herniation will compression of only one level is gen- been developed. Block et al10 report- result in a failure to relieve leg pain erally inadequate in a patient with

Volume 14, Number 9, September 2006 535 Failed Back Surgery Syndrome: Diagnostic Evaluation

Table 2 quires a fusion for relief of symp- termediate when pain recurs or new toms may have acceptable relief of symptoms occur approximately 1 to Classification of Failed Back pain but experience recurrence with 6 months after surgery; and late Surgeries a symptomatic pseudarthrosis. Sim- when the patient has experienced at Temporal factors ilarly, the patient with both a pseud- least 6 months of acceptable pain re- Early (no improvement) arthrosis and a flat back may have lief. Additional factors in classifying Intermediate (1-6 mos) persistent symptoms with incom- failed surgery include the type of in- Late (>6 mos) plete correction of the flat back. dex spinal surgery performed and the location of the pain. Index surgical procedure Progressive Disease Diskectomy Recurrence of symptoms may be Temporal Factors Spinal stenosis decompression caused by an ongoing degenerative No Relief or Early Onset of Fusion process or accelerated by alterations New Symptoms Deformity correction in spinal biomechanics created by Following surgery, the patient Pain location prior surgery. Recurrent disk herni- should experience some improve- Spine (lower back) ations occur in 5% to 15% of pa- ment in pain even though complete Lower extremity tients;14 almost half occur at a new initial relief postoperatively is not Widespread level or on the contralateral side. anticipated. When no change in The nerve roots may become teth- symptoms is reported, the surgeon ered because of scarring and thus be- must consider that the symptomat- multiple pain origins, such as foram- come less able to adapt to facet hy- ic pathology was not addressed and inal stenosis as well as a herniated pertrophy or other degenerative that wrong-level surgery or the disk, or multiple levels of spinal changes. Stability of a fused segment wrong procedure was performed. stenosis. Another example of select- will increase load onto the adjacent Another possible reason for lack of ing a less-than-optimal procedure is segments and accelerate disk degen- immediate improvement is that the performing a posterior fusion to ad- eration in a process called ″transi- procedure did not adequately address dress discogenic pain. These patients tion syndrome.″15,16 This syndrome the patient’s pathology. The most often have good results after revision occurs within 10 years in up to 25% likely causes are inadequate remov- anterior interbody fusion.12,13 of patients who undergo anterior cer- al of an extruded disk fragment, in- vical fusion.15 In one lumbar spine complete decompression, and failure Poor Technique study with a mean 5-year follow-up, to address pathology at an adjacent Even with correctly identified pa- 31 of 83 patients (36%) had radio- segment. Similarly, failure to identi- thology and an appropriately select- graphic evidence of adjacent seg- fy all of the causes of the patient’s ed procedure, the result will be ment degeneration.16 A similar pro- symptoms may result in immediate poor if the surgery is incompletely or cess may occur with time at the failure. For example, a patient may inappropriately executed (eg, incom- sacroiliac joint after lumbar fusion have continued pain if treatment of plete decompression, creation of with degeneration extended to the L5-S1 spondylolisthesis did not ad- iatrogenic instability). Additional sacrum. In addition to the possibili- dress pain arising from the L4-5 ad- examples are failure to adequately ty of disk changes, stenosis and/or jacent disk. Partial pain relief may be place or recess a transforaminal lum- instability may develop at the adja- related to incomplete diagnostic bar interbody fusion or posterior cent segments. workup and/or a procedure that only lumbar interbody fusion graft so that partially addressed the symptom- it impinges on neural structures. In- Classification of producing pathology. appropriate pedicle screw placement Patients With Failed Severe leg pain or temperature may result in neural impingement Back Surgery differences in the extremities imme- and radiculopathy. Complications diately after surgery warrant special must be diagnosed in a timely fash- There is no accepted classification attention. This may arise from vas- ion and adequately treated. for failed back surgery. Identification cular occlusion or injury or from of several key items may be helpful, compartment syndrome. When puls- Failure to Achieve the Goal such as the length of time between es are not palpable, a Doppler exam- of Surgery surgery and the onset of pain (Table ination of the extremities should be Failed spine surgery occurs when 2). Onset is considered immediate or performed. When none of the above the goals of surgery are not com- early when pain or symptoms either are abnormal, then nerve root injury pletely achieved. The patient with present immediately following sur- should be considered. If pedicle instability or degeneration who re- gery or recur within 2 to 3 weeks; in- screws or fusion cages have been in-

536 Journal of the American Academy of Orthopaedic Surgeons Richard D. Guyer, MD, et al serted, their position should be as- Late Postoperative Pain location of pain is useful. The pa- sessed. Imaging in patients with me- Some patients have an acceptable tient who remains symptomatic af- tallic implants can be difficult to result for up to 6 months postopera- ter stenosis decompression, with lit- interpret because of artifact. In these tively before pain redevelops. The tle or no immediate relief of leg patients, computed tomography most likely cause is recurrent pa- symptoms, may not have been (CT) myelography is helpful in iden- thology at the same or adjacent seg- adequately decompressed, or the tifying compression of the thecal sac ments. In patients who have under- pain may be arising from another or nerve roots. In the case of fusion gone fusion, a nonunion may source. This pain can be caused by cages or interbody bone graft, severe become symptomatic during this wrong-level surgery, failure to diag- radicular pain can be caused by disk time. Not infrequently, increasing nose and decompress the lateral re- tissue displaced by the interbody im- pain develops following completion cess or foraminal stenosis, or failure plants compressing the nerve roots. of rehabilitation and permission to to diagnose and decompress addi- In such cases, early reintervention is return to work. tional locations of stenosis. Early re- indicated to address the offending turn of similar radicular and low implant or disk tissue. Index Surgical Procedure back symptoms may represent either Another cause of persistent leg Diskectomy failure to diagnose preexisting insta- pain may be the stretching of the Microdiskectomy yields good re- bility or the development of iatro- nerve roots during placement of in- sults in 70% of properly selected pa- genic instability. terbody devices. When direct com- tients.17 In the remaining patients, Progressive scoliosis, rotary sub- pression of the nerve roots has been persistent or recurrent pain may be luxation, or spondylolisthesis may ruled out, this may be the most like- related to neurologic compression develop after wide decompression. ly cause of the radicular pain. Typi- that was not reversed by surgery, an One of the most common causes of cally, it resolves over the course of incomplete diskectomy or retained surgical failure is incomplete relief several weeks to months, and rein- disk fragments, recurrent disk herni- of the lateral recess and foraminal tervention is not indicated. ation, or changes related to altered stenosis. During decompressive sur- biomechanics of the operated seg- gery, the areas beneath the facet and Subacute Onset of Pain ment. For patients with significant the foramina should be carefully During the intermediate postop- pain after diskectomy, stratification probed and the mobility of the root erative period (4 weeks to 6 months), into early or late failures is useful to assessed. A methodical approach to some patients do well initially and the surgeon in determining the etiol- probing and inspecting the central then report a recurrence of pain or ogy of the pain. Early failure can canal, lateral recess, and foramen the onset of new symptoms. The lo- point to poor patient selection, such minimizes the chance of inadequate cation and character of the current as psychosocial factors, incorrect di- decompression in both the initial pain should be assessed in relation to agnosis, the wrong procedure, or oc- and salvage operations. the symptoms for which surgery was cult infection. The onset of pain fol- Late causes of pain following a performed. The surgeon also must lowing a good surgical result may be successful initial operation general- determine whether the symptoms indicative of a recurrent disk herni- ly fall into the categories of recur- are related to a specific event or de- ation, instability of the operated seg- rent stenosis at the same level, a veloped gradually. It is not unusual ment, or disease at a different disk new area of stenosis, disk hernia- for patients to report some new pain level. tion, or fibrosis (whether perineural, as they begin an active postoperative A subset of patients following dis- epidural, or arachnoiditis). rehabilitation program. Generally, kectomy experience partial relief this can be addressed with anti- with varying degrees of persistent Lumbar Fusion and Deformity inflammatory medication and/or re- pain. This may be the case in pa- Correction duced activity, followed by a slower tients who had surgery for a long- Failures following lumbar fusion progression to more advanced activ- standing compression of a nerve root are most often related to poor iden- ities. Of greater concern are severe that resulted in chronic intrinsic tification of surgical indications. symptoms that develop suddenly, neuropathy. Back pain following a period of relief particularly after a fall or trauma. from symptoms may be caused by ad- Such symptoms may be related to Lumbar Stenosis jacent segment degeneration, pseud- recurrent disk herniation, or hard- Decompression arthrosis, instrumentation-related ware or graft failure or displacement. As with patients who underwent stress phenomena (eg, spondylolysis, Iatrogenic causes, such as symptoms previous diskectomy surgery, classi- pedicle stress fracture), adjacent seg- from instability, may develop during fication of lumbar stenosis by timing ment instability, instrumentation this postoperative phase. of symptom onset and predominant failure, compression fracture above

Volume 14, Number 9, September 2006 537 Failed Back Surgery Syndrome: Diagnostic Evaluation

Figure 2 cause traction neurapraxia or direct Pain Location trauma to the cauda equina, individ- As in the evaluation of any pa- ual nerve roots, or ganglia. These tient with back pain, careful assess- complications can be recognized by ment of the location and pattern of immediate postoperative symptoms the patient’s pain can provide valu- such as severe radicular pain, motor able information. Generally, it is im- dysfunction, or cauda equina syn- portant to determine whether the drome. Before accepting such a diag- primary complaint is pain in the nosis, however, the surgeon must back or in one or both of the lower determine that all hardware had extremities. Widespread pain pat- been properly inserted. terns more often indicate a psy- Late-onset leg pain is most often chogenic and/or neuropathic compo- related to adjacent segment degener- nent. Although the surgeon must be ation (Figure 2), degenerative spondy- aware of these possibilities, a physi- lolisthesis, or focal spinal stenosis. ologic cause of pain must be deter- Occasionally, hypertrophic pseudar- mined by exclusion, particularly throsis may produce root or thecal when the patient reports symptoms sac impingement. that may be related to problems such Should the instrumentation in- as malpositioned implants, neural clude a sagittal transition area or the compression, infection, or tumor. majority of the lumbar spine, the pa- tient may have flat back syndrome. Lower Extremity This condition is caused by the Lower extremity pain has many shape and rigidity of the rods used to etiologies. Vascular claudication can straighten the deformity. Patients masquerade as neurogenic claudica- may present with difficulty standing tion. Various entrapment syndromes erect. Many patients try to compen- of the sciatic, peroneal, femoral, lat- sate for the flat back by bending at eral femoral cutaneous, tibial, and Standing anteroposterior radiograph of the hips and/or knees, resulting in digital nerves may cause pseudora- a 68-year-old man demonstrating even poorer posture. dicular pain. Diabetic neuropathy degeneration of a segment (L5-S1) Little conclusive data are avail- may simulate radiculopathy. Pelvic adjacent to a previous fusion (L1-L5). able on the role of instrumentation tumors, infections, inflammatory in the presence of a solid fusion as a processes, and aneurysms may com- an instrumented segment, or steno- cause for pain in the absence of mal- press the lumbosacral plexus. sis of an adjacent segment. Several positioned implants. In our experi- Typically, pain radiating below authors have reported that persistent ence, hardware removal often is ben- the knee in a dermatomal pattern is axial pain may be the result of pain- eficial, particularly in patients with the easiest to evaluate. This pain ful disrupted disks within a solidly a positive response to hardware in- pattern is generally related to nerve posteriorly fused segment.12,13 jection (ie, those whose pain was root compression. When the pain is New leg pain following lumbar temporarily relieved by an injection similar to the preoperative pain, the fusion has several possible etiolo- of anesthesia around the implants). surgeon must consider missed pa- gies. Instrument-related causes in- Instrumentation should not be re- thology as the source of ongoing clude misplaced pedicle or translam- moved until the patient has under- pain. The most likely sources in- inar facet screws, and fusion cages or gone an extensive diagnostic workup clude a missed extruded disk frag- structural bone graft placed into the to rule out other potential sources of ment or inadequate decompression neural foramen. Cages or structural pain, including psychological issues. of stenosis. Leg pain appearing im- graft placed through the anterior ap- The mechanism by which instru- mediately after surgery that is differ- proach may displace disk or bone mentation may cause pain is not ful- ent or more severe than the original fragments posteriorly into either the ly understood. Several studies have symptoms suggests malpositioned spinal canal or foramen. Intertrans- demonstrated an inflammatory re- instrumentation, including pedicle verse bone graft may become dis- sponse to metal debris from screws or interbody implants. Recur- placed into the spinal canal or ante- implants.18-20 One study, however, rent disk herniation is a possibility riorly onto the exiting nerve roots. reported that the problem was signif- in the patient who has experienced Use of fusion cages or intervertebral icant only in patients with pseudar- several months or more of pain relief graft via the posterior route may throsis.20 before presenting with onset of pain.

538 Journal of the American Academy of Orthopaedic Surgeons Richard D. Guyer, MD, et al

Figure 3

Lateral spine (A) and anteroposterior pelvis (B) radiographs of a 48-year-old man referred for treatment of lumbar spinal stenosis. Further history revealed groin pain more consistent with hip joint arthritis than neurogenic claudication. A, Spondylosis with foraminal stenosis, predominantly at L4-5 (arrow). B, Advanced arthrosis of both hip joints (arrows).

In the patient with radicular pain in generative conditions of the sacroil- dermatomal distributions or in a different radicular pattern, pathol- iac joint can cause groin, thigh, widespread patterns. Although these ogy may have developed at a differ- and/or back pain (Figure 3). Other po- are characteristics of psychogenic ent spinal level. However, the facet tential sources of back and leg pain pain, physiologic causes must not be joints can also produce pain into the must always be considered, even ruled out too quickly. It would be thigh, and occasionally below the when spinal pathology is evident. unusual for a patient with a relative- knee.21 A less clear clinical presentation ly clear preoperative clinical picture is that of back pain following spine to have a psychogenic presentation Back surgery. The pain may be related to shortly after surgery. One possible Back pain may be caused by pelvic muscle weakness following posteri- cause of the widespread pain is com- and abdominal inflammatory and in- or spine surgery. Pain may also arise plex regional pain syndrome or re- fectious entities, including kidney from a disrupted disk that was not flex sympathetic dystrophy. Sachs et and bladder infections, cholelithiasis/ addressed during the original sur- al22 reported that this occurs in ap- cholecystitis, psoas abscesses, and gery, such as pain from a disk in a pa- proximately 1.2% of patients follow- pancreatitis. Systemic rheumatologic tient operated on for spondylolisthe- ing spine surgery. Such patients problems, such as ankylosing sis. Back pain may also occur as a should be treated by a pain specialist spondylitis, regional enteritis, diffuse result of pain coming from a facet familiar with the diagnosis. idiopathic skeletal hyperostosis, joint. In the patient with an accept- Reiter syndrome, and rheumatoid ar- able result for 1 to 6 months who lat- Patient Evaluation thritis, can be missed or attributed to er reports back pain, instability of an asymptomatic herniated disk the operated segment should be con- Patients with failed back surgery re- found on magnetic resonance imag- sidered. quire careful assessment to deter- ing (MRI) scans. Thoracic and ab- mine the exact cause of symptoms dominal tumors and infections can Widespread Pain Patterns and the effect on the patients’ emo- cause flank and back pain, as can tho- Some patients present with pain tional and functional state. Because racic and abdominal aneurysms. De- either in patterns inconsistent with results of revision back surgery are

Volume 14, Number 9, September 2006 539 Failed Back Surgery Syndrome: Diagnostic Evaluation significantly poorer than those of in- Physical Examination may have neurologic compression dex surgical procedures, a thorough The physical examination is sim- that may require treatment. MRI evaluation is mandatory before pro- ilar to any initial patient evaluation. with and without gadolinium en- ceeding with further surgery. Non- Nonorganic physical findings should hancement is the most sensitive test spinal causes of leg and back pain be assessed, as described by Waddell for evaluating these patients.24 En- must be considered once the spine- et al.23 Waddell signs include behav- hancement with gadolinium results related causes are ruled out. Even ior such as superficial or nonana- in increased signal in vascularized though an obvious nonspinal cause tomic tenderness, overreaction to tissues, especially epidural scar. (eg, psychosocial source) may be stimuli, or reports of pain during Comparing enhanced and nonen- present, a thorough spinal workup evaluations that are designed not to hanced sequences can accurately be painful. More than two Waddell distinguish epidural scar from non- should be performed. Similarly, all findings strongly predicts poor out- enhancing recurrent disk herniation. patients should undergo a thorough come, regardless of spinal pathology. In addition, gadolinium enhance- and detailed expanded history and Standard tests of posture, gait, ten- ment in the intervertebral disk and physical examination. Such an ap- derness, range of motion, nerve root vertebral bodies may demonstrate proach can help avoid serious and tension signs, and neurologic exam- the presence of postoperative infec- potentially devastating omissions. ination are performed. The examina- tion. tion should exclude other common CT myelography is indicated in History causes of leg pain, incorporating ex- the patient with contraindications Details of postoperative symp- amination of the hip and knees for to MRI, with stainless steel hard- toms and their relation to preopera- pain and range of motion as well as ware, or whose images are degraded tive clinical symptoms will provide assessment of peripheral pulses. by titanium hardware. CT myelogra- insight into possible causes of persis- phy is also useful for evaluating the tent low back pain. Careful review of Imaging patient with dynamic problems (eg, medical records, surgical reports, Biplanar standing radiographs are instability, facet impingement) or and radiographs can identify events obtained to evaluate the site of prior whose spine is less well visualized such as wrong-level surgery or incor- surgery, changes in alignment, de- by MRI (eg, patient with scoliosis). rect initial diagnosis. As with all spi- gree of resection of the posterior el- Evaluation of patients who have nal conditions, the degree of noci- ements, and progressive degenera- had spinal fusion, especially with in- ceptive back pain and neuropathic tive changes. When fusion has strumentation, is often difficult. leg pain is essential to planning fur- occurred at L5-S1, an anteroposteri- Pseudarthrosis should be suspected ther treatment. Assessment of the or Ferguson view may be helpful. in the presence of a short period of medical history, review of systems, Flexion-extension radiographs are pain relief followed by progressively and social history can identify co- indicated in the patient who has had increasing mechanical back pain. morbidities and the possibility of so- fusion or has any possibility of insta- Plain radiographs, particularly flex- matization or addiction disorders. bility. The location of implanted ion and extension views, have been Depression is common in most hardware and any loosening or sub- used to assess incorporation of the patients with failed back surgery and sidence should be scrutinized. fusion. Progressive lucency around is assessed by determining the pres- A fused or sclerotic sacroiliac screws or evidence of hardware fail- ence or absence of classic neuropsy- joint may explain buttock and poste- ure is suggestive of pseudarthrosis. chopathic signs, such as sleep distur- rior thigh pain that is unrelieved by Lucencies around the hardware or bance, loss of appetite, weight surgery performed on an asymptom- subsidence have been found to have change, feelings of despair, loss of atic, abnormal-appearing disk. Hip a poor correlation with findings sexual desire, irritability, and inabil- joint pathology, such as osteoarthri- at the time of open revision, ity to make decisions. Other factors tis, osteonecrosis, or unrecognized however.25-27 Pseudarthrosis is likely to assess include substance abuse, stress fractures, may be the true when motion is present on flexion- work history and motivation for re- source of groin pain radiating into extension radiographs. CT with fine- turn to work, and personality disor- the thigh. The iliac crest bone graft section coronal and sagittal recon- ders. Undertaking additional surgery site also should be evaluated clini- structions is generally best to deter- without addressing these psychoso- cally and radiographically to evalu- mine fusion status. As with any cial factors increases the risk for fur- ate the possibility of a pelvic fracture imaging study, however, this may ther failure. Constitutional symp- or sacroiliac joint dysfunction. fail to yield results correlative with toms (eg, night sweats, fever, chills, Neural imaging is indicated in findings at revision, particularly weight loss) may indicate occult in- most patients with FBSS. Even pa- with metallic implants that create fection. tients with pain limited to the back artifacts on imaging.

540 Journal of the American Academy of Orthopaedic Surgeons Richard D. Guyer, MD, et al

In more complex cases, the over- the probability of a poor outcome. havior, and physiologic changes that all sagittal balance should be as- Referral to a psychologist or psychi- cause the wind-up phenomenon, sessed. On standing 36-inch radio- atrist who specializes in chronic with the patient becoming more graphs, the weight-bearing line pain is recommended before further sensitive to pain. should pass from C7 to the sacrum. surgery in many patients with FBSS Until recently, many care provid- Displacement of this line anteriorly who have chronic pain. In general, ers did not have an adequate appreci- may indicate flat back syndrome. the patient with significant abnor- ation for the physical causes of pain malities on psychometric testing is sensitization that can occur in pa- Electrodiagnostic Studies difficult to rehabilitate into a good tients with chronic pain. Previously, Electromyograms (EMGs) and surgical candidate. Depression and pain was described as a hard-wired nerve conduction velocity (NCV) its accompanying sleep disturbance system similar to a telephone, with studies are rarely indicated but may are common and should be treated signals sent from the periphery to be helpful to evaluate extraspinal both pre- and perioperatively. the brain. This may be an appropri- neural compression, assess the se- ate analogy for the patient with verity and location of nerve injury, Diagnostic Block acute pain, but it is an oversimplifi- and discriminate from other causes Selective nerve root blocks are of neuropathic pain, such as periph- helpful to confirm exact localiza- cation for the patient with chronic eral neuropathy. Physical examina- tions of neural abnormalities and pain. With chronic pain, plasticity tion findings are sometimes difficult perhaps to predict outcomes of sur- occurs in the pain modulation sys- to interpret in patients with FBSS, gery. Although important informa- tem, creating increased pain sensiti- and more objective diagnostic tests tion is obtained from both the anes- zation to noxious stimulation. Pain, (eg, EMG, NCV) can be valuable, al- thetic response and, in the long inactivity, change in diet, lack of though they may not be predictive of term, from the corticosteroid re- sleep, and stress can amplify pain outcome of further surgery. sponse, controlled studies docu- and lead to physiologic changes. A menting their ability to predict out- stimulus that generally is not pain- Laboratory Tests come in the patient group with FBSS ful can be painful in the patient with The patient presenting with con- are lacking. The use of provocative chronic pain. Although such pa- stitutional symptoms, a history of diskography is controversial, and the tients can benefit from psychologi- infection, or prolonged wound drain- resultant pain provocation is even cal counseling and participation in a age should be assessed for occult in- less well understood in patients with pain program, a physical cause for at fection. Early or midterm onset of prior surgery. Diskography has iden- least a portion of the ongoing symp- severe low back pain of a different tified painful disk segments after toms cannot be ruled out. In these quality after diskectomy may indi- posterior fusion with good clinical patients, any of the aforementioned cate diskitis. Erythrocyte sedimenta- outcomes following interbody fu- physical problems could be responsi- tion rate and C-reactive protein lev- sion. Diskography also can be used ble for pain related to failed back sur- els are usually elevated, although to identify painful transitional mo- gery. Patients whose symptoms are they are not specific for infection. tion segments. Similarly, diagnostic seemingly out of proportion for their C-reactive protein returns to a nor- facet blocks may be used to identify physical condition may be referred mal level sooner than does the painful transitional motion seg- to a psychologist or psychiatrist for erythrocyte sedimentation rate, usu- ments. evaluation and possible interven- ally in 14 days, and may be useful in determining response to treatment. tion. Components of the evaluation Chronic Pain may include a structured interview Psychological Assessment The psychological component of and formal testing for personality The psychological state of the pa- failed surgery and its impact on pa- profile, depression, and coping skills. tient with FBSS is assessed by care- tients’ lives cannot be overlooked. The psychologist often can play a ful review of the medical history and Chronic pain and disability often helpful role in identifying behavior- physical examination. A low thresh- lead to depression and anxiety and al components of the patient’s pain old for more careful analysis is indi- can result in interference with daily and strategies to manage them. Such cated in this population. Although activities, recreation, and sleep. problems may include stress at many techniques are available to Medications to treat chronic pain of- work, problems with the health care measure psychological distress, the ten have the undesired effect of ag- system, or issues with family mem- most popular is the MMPI. High gravating these psychologic condi- bers. Intervention may include re- scores on the scales of hysteria, de- tions. All these factors can put a laxation therapy and assistance with pression, and hypochondria predict patient on a spiral of pain, pain be- coping skills.

Volume 14, Number 9, September 2006 541 Failed Back Surgery Syndrome: Diagnostic Evaluation

Prevention eratively, any complication should found, a well-thought-out and exe- be identified promptly and treated cuted plan may provide a good result. The best patient management is the aggressively even if revision is re- prevention of failed back surgery. quired. Delays often lead to further References The most important element in pre- neural injury. vention is presurgical patient assess- Citation numbers printed in bold type indicate references published ment. Symptoms should be of suffi- Summary cient severity and character to within the past 5 years. warrant surgery. In most patients, Because of the very nature of their 1. Block AR, Gatchel RJ, Deardorff WW, surgery is indicated for disabling problem, patients with FBSS fall into Guyer RD: The Psychology of Spine radicular or mechanical axial pain, a high-risk category for failure fol- Surgery. Washington, DC: American neurologic changes, or progressive lowing subsequent surgical treat- Psychological Association, 2003. 2. Spengler DM, Freeman C, Westbrook deformity. The symptoms must cor- ment. Lack of success in addressing R, Miller JW: Low-back pain follow- relate with physical examination ab- the original problem, accompanied ing multiple lumbar spine procedures: normalities and the imaging studies. by new problems stemming from the Failure of initial selection? Spine The physical examination should as- index procedure, can lower the like- 1980;5:356-360. sess findings of pain behavior (ie, lihood and degree of success of sub- 3. Wiltse LL, Rocchio PD: Preoperative psychological tests as predictors of Waddell signs) as well as other diag- sequent intervention. Often, the pa- success of chemonucleolysis in the noses (eg, hip arthrosis, vascular dis- tient presents with a complex treatment of the low-back syndrome. ease, peripheral neuropathy) that history of multiple failed operations J Bone Joint Surg Am 1975;57:478- would explain the pain symptoms. for conflicting diagnoses. Documen- 483. At surgery, a time-out should be tation and studies are often incom- 4. Dhar S, Porter RW: Failed lumbar spi- nal surgery. Int Orthop 1992;16:152- used in which the correct level to be plete. The surgeon must persist in 156. operated on is confirmed by the cir- delineating the causes of pain and 5. Trief PM, Grant W, Fredrickson B: A culating nurse, anesthesiologist, and failure of the previous operation. For prospective study of psychological surgeon. Usually, this is confirmed some diagnoses, such as recurrent predictors of lumbar surgery out- radiographically at the time of the herniation, pseudarthrosis, or adja- come. Spine 2000;25:2616-2621. 6. Waddell G, McCulloch JA, Kummel surgical procedure. Confusion is cent segment degeneration, the re- E, Venner RM: Nonorganic physical most likely to occur when the pa- sults of revision surgery may be grat- signs in low-back pain. Spine 1980;5: tient has a transitional vertebra. This ifying. Other conditions, such as 117-125. can be avoided when, during surgical arachnoiditis and epidural/perineural 7. Klekamp J, McCarty E, Spengler DM: planning, the surgeon is aware of po- fibrosis, once regarded as having a Results of elective lumbar discecto- my for patients involved in the work- tential confusion and carefully iden- bleak outlook, are now treated suc- ers’ compensation system. J Spinal tifies intraoperative landmarks. Cor- cessfully with spinal cord stimula- Disord 1998;11:277-282. rectly identifying the levels in the tion in some patients.28 Because pa- 8. Taylor VM, Deyo RA, Ciol M, et al: thoracic spine is more difficult than tients with FBSS have chronic pain Patient-oriented outcomes from low in the lumbar or cervical regions. and may have emotional problems back surgery: A community-based study. Spine 2000;25:2445-2452. Scout imaging that includes the related to their longstanding health 9. Waddell G, Main CJ, Morris EW, Di craniocervical or lumbosacral junc- problems, evaluation by a psycholo- Paola M, Gray ICM: Chronic low- tion facilitates counting from an eas- gist familiar with patients who have back pain, psychologic distress, and ily discernible point. In addition, chronic back pain is helpful. Preop- illness behavior. Spine 1984;9:209- identification and matching of other erative screening by a psychologist 213. 10. Block AR, Ohnmeiss DD, Guyer RD, landmarks, such as fractures or os- can help avoid additional surgery in Rashbaum RF, Hochschuler SH: The teophytes, can be helpful in confirm- patients whose personality or emo- use of presurgical psychological ing the appropriate treatment level. tional state is likely to preclude a fa- screening to predict the outcome of Following spine decompression, vorable surgical result. spine surgery. Spine J 2001;1:274- the nerve root should be checked for Careful diagnosis of the cause of 282. 11. Wong DA: Present initiatives and fu- mobility and the neuroforamina pal- persistent pain is invariably the first ture directions: How best to serve our pated to ensure adequate opening. step in appropriate treatment. An or- patients and members. North Ameri- When instrumentation has been ganized evaluation plan for patients can Spine Society Presidential Ad- placed, the spinal cord and neurofo- with FBSS should include assessing dress, San Diego, CA. Spine J 2004;4: ramina should be inspected for mis- details of any pain-free interval, the 8-14. 12. Weatherley CR, Prickett CF, O’Brien placed metal; if possible, the posi- location of the pain, and appropriate JP: Discogenic pain persisting despite tion of the instrumentation should use of imaging, injection, and neural solid posterior fusion. J Bone Joint be verified radiographically. Postop- studies. Should a clear diagnosis be Surg Br 1986;68:142-143.

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13. Barrick WT, Schofferman JA, Rey- 18. Johnson D, Tucci M, McGuire R, MR imaging of the postoperative lum- nolds JB, et al: Anterior lumbar fusion Hughes J: Evaluation of the bar spine: Assessment with gadopen- improves discogenic pain at levels of biomaterial-interface of screw tetate dimeglumine. AJRAmJ prior posterolateral fusion. Spine threads in patients having clinical Roentgenol 1990;155:867-872. 2000;25:853-857. pain. Biomed Sci Instrum 1996;32: 25. Brodsky AE, Kovalsky ES, Khalil MA: 14. Carragee EJ, Han MY, Suen PW, Kim 127-133. Correlation of radiologic assessment D: Clinical outcomes after lumbar 19. Mody DR, Esses SI, Heggeness MH: A of lumbar spine fusions with surgical discectomy for sciatica: The effects of histologic study of soft-tissue reac- exploration. Spine 1991;16(6 suppl): fragment type and anular compe- tions to spinal implants. Spine 1994; S261-S265. tence. J Bone Joint Surg Am 2003;85: 19:1153-1156. 26. Blumenthal SL, Gill K: Can lumbar 102-108. 20. Wang JC, Yu WD, Sandhu HS, Betts F, spine radiographs accurately deter- 15. Hilibrand AS, Carlson GD, Palumbo Bhuta S, Delamarter RB: Metal debris mine fusion in postoperative pa- MA, Jones PK, Bohlman HH: Radicu- from titanium spinal implants. Spine tients? Correlation of routine radio- lopathy and myelopathy at segments adjacent to the site of a previous ante- 1999;24:899-903. graphs with a second surgical look at rior cervical arthrodesis. J Bone Joint 21. Mooney V, Robertson J: The facet syn- lumbar fusions. Spine 1993;18:1186- Surg Am 1999;81:519-528. drome. Clin Orthop Relat Res 1976; 1189. 16. Kumar MN, Baklanov A, Chopin D: 115:149-156. 27. Larsen JM, Rimoldi RL, Capen DA, Correlation between sagittal plane 22. Sachs BL, Zindrick MR, Beasley RD: Nelson RW, Nagelberg S, Thomas JC changes and adjacent segment degen- Reflex sympathetic dystrophy after Jr: Assessment of pseudarthrosis in eration following lumbar spine fu- operative procedures on the lumbar pedicle screw fusion: A prospective sion. Eur Spine J 2001;10:314-319. spine. J Bone Joint Surg Am 1993;75: study comparing plain radiographs, 17. Atlas SJ, Keller RB, Chang Y, Deyo 721-725. flexion/extension radiographs, CT RA, Singer DE: Surgical and nonsurgi- 23. Waddell G, McCulloch JA, Kummel scanning, and bone scintigraphy with cal management of sciatica secondary E, Venner RM: Nonorganic physical operative findings. J Spinal Disord to a lumbar disc herniation: Five-year signs in low-back pain. Spine 1980;5: 1996;9:117-120. outcomes from the Maine Lumbar 117-125. 28. LeDoux MS, Langford KH: Spinal cord Spine Study. Spine 2001;26:1179- 24. Ross JS, Masaryk TJ, Schrader M, stimulation for the failed back syn- 1187. Gentili A, Bohlman H, Modic MT: drome. Spine 1993;18:191-194.

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