Lumbar Stenosis Without Spondylolift - A Review

Transcription

1 J Neurosurg: Spine 2: , 2005 Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 10: fusion following decompression in patients with stenosis without spondylolisthesis DANIEL K. RESNICK, M.D., TANVIR F. CHOUDHRI, M.D., ANDREW T. DAILEY, M.D., MICHAEL W. GROFF, M.D., LARRY KHOO, M.D., PAUL G. MATZ, M.D., PRAVEEN MUMMANENI, M.D., WILLIAM C. WATTERS III, M.D., JEFFREY WANG, M.D., BEVERLY C. WALTERS, M.D., M.P.H., AND MARK N. HADLEY, M.D. Department of Neurosurgery, University of Wisconsin, Madison, Wisconsin; Department of Neurosurgery, Mount Sinai Medical School, New York, New York; Department of Neurosurgery, University of Washington, Seattle, Washington; Department of Neurosurgery, Indiana University, Indianapolis, Indiana; Departments of Orthopedic Surgery and Neurosurgery, University of California at Los Angeles, California; Department of Neurosurgery, University of Alabama at Birmingham, Alabama; Department of Neurosurgery, Emory University, Atlanta, Georgia; Bone and Joint Clinic of Houston, Texas; and Department of Neurosurgery, Brown University, Providence, Rhode Island KEY WORDS lumbar spine stenosis spondylolisthesis fusion practice guidelines Recommendations Standards. There is insufficient evidence to recommend a treatment standard. Guidelines. There is insufficient evidence to recommend a treatment guideline. Options. 1) In situ posterolateral lumbar fusion is not recommended as a treatment option in patients with lumbar stenosis in whom there is no evidence of preexisting spinal instability or likely iatrogenic instability due to facetectomy. 2) In situ lumbar PLF is recommended as a treatment option in addition to decompression in patients with lumbar stenosis without deformity in whom there is evidence of spinal instability. 3) The addition of pedicle screw instrumentation is not recommended in conjunction with PLF following decompression for lumbar stenosis in patients without spinal deformity or instability. Rationale Abbreviations used in this paper: PLF = posterolateral fusion; RCT = randomized controlled trial. 686 The surgical management of patients with lumbar stenosis without spondylolisthesis has traditionally involved posterior decompressive procedures including laminectomy or laminotomy and judicious use of partial medial facetectomies and foraminotomies, with or without discectomy. In a subset of patients who have undergone lumbar laminectomy progressive vertebral displacement and slippage at or adjacent to the decompressed levels will be demonstrated. This has led some surgeons to recommend the routine use of PLF, with or without placement of instrumentation, to achieve an in situ arthrodesis following decompression. Given the additional blood loss and fusion-related risk, its use as an adjunct in patients with lumbar stenosis without deformity remains controversial. The purpose of this review is to examine the literature concerning the use of PLF after decompression in patients with lumbar stenosis without deformity. The following two key questions are examined. 1) Is there evidence that the addition of PLF improves outcome compared with decompression alone in patients with lumbar stenosis without deformity? If so, which patients with lumbar stenosis are likely to benefit from the use of adjunctive spinal fusion? 2) Is there evidence that the application of spinal instrumentation, in addition to PLF, improves outcome compared with fusion without instrumentation in this patient population? Search Criteria A computerized search of the database of the National

2 Spinal stenosis without spondylolisthesis Library of Medicine from 1966 to March 2003 was conducted using the search terms lumbar stenosis and fusion and spinal surgery or lumbar stenosis and arthrodesis. The search was restricted to the English language and yielded 204 references. The titles and abstracts of each reference were reviewed, and papers not concerned with decompression and fusion for lumbar stenosis were discarded. Thirty-two references were identified that provided either direct or supporting evidence relevant to the use of spinal fusion in the treatment of lumbar stenosis without spondylolisthesis. These papers were reviewed, and relevant references from their bibliographies were identified. All papers providing Class III medical evidence or better regarding the use of fusion and decompression for nondeformity-based lumbar stenosis are summarized in Table 1. Additional supportive data are provided by references listed in the bibliography. Scientific Foundation In the treatment of symptomatic lumbar stenosis lumbar decompression has been demonstrated to have a clinical efficacy of between 60 and 75% in RCTs. 29 In their metaanalysis of the available literature, Turner, et al., 29 identified an overall 64% good outcome rate for all surgically treated patients with lumbar stenosis. The surgery-derived benefit decreased over time, however, with increased patient dissatisfaction with a longer follow-up duration. 24,29 In the lumbar stenosis population, several subgroups have been consistently identified and subcategorized. These include patients with preexisting spondylolisthesis, scoliosis, prior destabilizing laminectomies, and the presence of segmental vertebral motion on flexion extension radiographs. 1,3,4,15 21 Longitudinal studies have identified a discreet proportion of patients with lumbar stenosis without deformity who have undergone decompression and in whom progressive lumbar spinal instability, deformity, and/or spondylolisthesis have developed. The reported incidence of this progressive slippage has ranged from as low as 9% in patients with no evidence of preoperative lumbar spinal instability 15 to as high as 73% in those with preoperative evidence of spondylolisthesis. 8 In an analysis of 100 laminectomy-treated patients, Caputy and Luessenhop 4 found that the main risk factor for 5- year clinical and radiographic failure was preoperative spondylolisthesis. In topic reviews and metaanalyses of the literature, several authors have stressed the importance of identifying spondylolisthesis and scoliosis as significant risk factors for delayed clinical and radiographic failure after lumbar decompressive procedures. 8,25,27,29 Multilevel laminectomies and extensive (wide) decompression have also been shown to have a positive correlation with an increased incidence of progressive spondylolisthesis. 13,26 Whereas spondylolisthesis and scoliosis are easily identified on radiography as potential risks for postdecompression instability, several techniques have been advocated as a means by which to identify more subtle forms of preoperative spinal hypermobility or deformity. The most popular of these methods are criteria based on dynamic lateral flexion extension images. 10,11,31,32 In general, PLF at the time of lumbar decompression has been reserved for patients with lumbar stenosis and preoperative radiographic evidence of hypermobility or deformity in an attempt to minimize the chance of delayed symptomatic spondylolisthesis or deformity. 3,7,28,30 Jolles, et al., 15 reported that only in 9% of 155 decompression-treated patients without preoperative evidence of instability did delayed slippage eventually develop. Hopp and Tsou 13 as well as others 3,8 have reported that aggressive wide decompression and facetectomy performed at the time of the decompression result in iatrogenic destabilization in certain patients and may account for delayed deformity in those with stenosis and normal preoperative alignment. At the time of lumbar decompression in patients without instability PLF has been performed to prevent lateonset instability and potentially to improve outcome. Cornefjord, et al., 6 retrospectively reviewed 124 patients of whom 96 were available for follow up. Three treatment groups were described: 59 patients underwent lumbar spinal fusion with or without placement of supplemental instrumentation, in addition to decompression. In all surgical patients statistically significant benefits were demonstrated for walking tolerance, leg pain, and back pain (p 0.001), with an overall 65% satisfaction rate at 7 years. No significant differences in outcome were identified between those who underwent fusion and those who did not. This paper provides Class III medical evidence suggesting that the addition of fusion does not improve longterm outcomes in patients with stenosis and no evidence of preoperative spinal instability. Grob, et al., 10 randomized 45 patients with stenosis but no evidence of preoperative spondylolisthesis or instability into three treatment groups: decompression alone (Group 1), decompression and singlesegment fusion (Group 2), and decompression and multisegment fusion (Group 3). In all three treatment groups patients reported significant improvement in ambulatory status and pain (p 0.001). Blood loss and operative duration were, however, higher in the lumbar fusion groups. No differences among the three groups were noted on a patient satisfaction survey administered at the last follow-up evaluation. This paper provides Class III medical evidence (due to the small sample size and nonvalidated outcome measure) suggesting that the addition of PLF does not improve outcome following decompression in patients with lumbar stenosis and no preoperative deformity or instability. Herron and Mangelsdorf 12 reported their experience with a retrospective cohort study of 140 patients treated for symptomatic lumbar stenosis. Nine patients underwent fusion in addition to decompression. Because of this extremely small sample, the authors were unable to demonstrate a significant benefit to fusion. Rompe, et al., 24 reviewed their results with 117 consecutive patients in whom they performed surgery for lumbar stenosis: 90 patients underwent decompression only and 27 underwent decompression and fusion. Both groups of patients reported improved walking endurance and pain scores (p 0.01). There were no statistical differences in outcome between the fusion and nonfusion groups. Nasca 21 first reported a retrospective series of 80 patients, and 2 years later he described 114 patients treated with lumbar stenosis. 22 He classified patients based on the anatomical location of stenosis, either in the lateral recess, central canal, or both, and noted the presence of associated scoliosis or deformity. In addition to decompression, fusion was performed in 51 patients and decompression alone was per- 687

3 D. K. Resnick, et al. TABLE 1 Summary of studies involving postdecompression fusion in patients with degenerative lumbar disease* Authors & Year Class Description Comment Tile, et al., 1976 III Retrospective series of 90 patients w/ lumbar stenosis. All had improvement in claudication symptoms. Patients No comparison of fusion vs no fusion in matched w/ DS tended to have progressive slip. Recommended fusion in this group. groups. Recommended fusion in patients w/ listhesis. Shenkin & Hash, 1979 III Retrospective series of 59 patients w/ intractable pain multilevel laminectomies. Although progressive slip noted Laminect alone associated w/ good outcomes, parin 6 15% of patients, overall results of laminect alone were good. ticularly in older patients. Hutter, 1985 III Retrospective review of 142 patients treated w/ PLIF: 78% good result. Technical report & case series. Nasca, 1987 III Retrospective review of 80 patients w/ lumbar stenosis. Paper very similar to that published in 1989 (see Nasca, 1989). Hopp & Tsou, 1988 III Retrospective study of 334 patients. Authors noted 17% reop rate for instability. Preop predictors of instability in- Recommended sparing dorsal elements as much as clude traction spurs, decreased disc height, listhesis, & scoliosis. possible during decompression. Recommended fusion in cases w/ preop risk factors. Nasca, 1989 III Retrospective review of 114 patients w/ lumbar stenosis. Divided into 4 groups: lat recess stenosis (15) (unilat de- Overall, noticed trend of better outcomes in each subcompression, 2 needed delayed fusion), central mixed (45 [16 fused]), prior lumbar surgery (43 [22 fused]), group w/ fusion except isolated recess stenosis. scoliosis (11/11 fused over major curve) overall good results achieved in 70%. The authors identified the fol- Subgroups identified who did better w/ fusion lowing groups who did better w/ fusion than decompression alone: listhesis, degenerated facets w/ collapsed than decompression alone. disc, radiographic instability, or scoliosis. Conley, et al., 1990 III Retrospective review of 25 patients, w/ 2-yr FU. All had intraop instability noted. Knodt rod facet fusions done. Basically a technique paper. Hypothesized better axial LBP outcomes. 15/25 had some movement on preop radiographs. Flawed by physician assessments. 72% fusion rate. Herkowitz & Kurz, 1991 III Primarily a listhesis paper. Included in prior metaanalysis & discussed here as supporting data regarding influ- Progressive deformity following decompression is ence of listhesis progression on outcome. associated w/ poor outcomes. Fusion prevents progressive deformity. Herron & Mangelsdorf, 1991 III Retrospective review of 140 patients. Only 9 underwent fusion. No correlation of outcome w/ fusion using 2 No conclusions drawn from this report. multivariate analysis. Caputy & Luessenhop, 1992 III Retrospective series of 100 patients treated w/ laminect alone; 5-yr FU in 88 patients. 27% failure rate at 5 yrs, Case series. No significant conclusions can be 29% listhesis. Main risk factor for poor outcome was listhesis. reached. Louis & Nazarian, 1992 III Retrospective review of 350 patients, 280 w/ 2-yr FU. Initially used fusion w/ screws/plates in 43% cases, then The use of fusion was associated w/ better relief of dropped to 17% of cases. Again only listhesis, instability, wide undercutting. Observed trend of better ob- LBP in some patient groups. jective patient criteria 85 vs 65% in patients w/ fusion. Mixed bag, sparse data. Turner, et al., 1992 III Metaanalysis on op for stenosis included 74 articles. Commented on poor quality of available studies very dif- Authors reported an overall 64% good outcome rate ferent outcome variables, op techniques. Of 74 articles 37 had fusion as op option. Critical of outcome measures used. for op of lumbar stenosis. Could not make statements regarding role of fusion. Bridwell, et al., 1993 III Pseudorandomized study of patients w/ stenosis due to DS. Patients who underwent instrumented PLF did better. Instrumented PLF valuable for patients w/ stenosis due to DS. Grob, et al., 1995 III RCT of 45 patients w/ stenosis & no instability or deformity. Patients divided into 3 groups: laminect, laminect No advantage to fusion in this population. fusion, laminect fusion w/ instrumentation. All patients had better walking & pain (p 0.001). Nonvalidated outcome measure used. Fox, et al., 1996 III Retrospective series of 124 patients treated w/ laminect; 32 treated w/ fusion as well. Mean FU was 5.8 yrs. Listhesis was major predictor of delayed slip/failure/ 31% of patients w/ normal alignments treated w/ laminect alone suffered a delayed slip; 73% had delayed reop. Motion was also important. 91% treated w/ slip if listhesis identified preop. fusion had good outcomes vs 75% w/ laminect alone. Yone, et al., 1996 III Retrospective series of 34 patients, mean age 68 yrs. Used flex ext films to assess instability. Patients divided into Concluded criteria useful in identifying those at risk 3 groups: 1 stable w/ laminect only, 7 unstable w/ laminect only, 10 unstable w/ laminect/instrumented fusion; for instability. In these patients, fusion improved JOA scores, Steffee/Knodt rods; groups similar preop in pain/functional scores. outcome (p 0.05). Patients w/ unstable fusion did just as well when fused as those w/o instability & w/o fusion. Katz, et al., 1997 III 272 patients mailed questionnaires 6 yrs postop. 71% had been treated w/ laminect alone, 14% in situ fusion, Fusion appeared to have a benefit. No clear benefit 15% instrumented fusion. Fusion patients were younger w/ greater preop pain. Similar leg pain, walking ca- of supplemental instrumentation was demonstrated. pacity, sickness profiles, & comorbidity. Niggemeyer, et al., 1997 III Metaanalysis of 30 articles that described 1668 cases: decompression, decompression & in situ fusion; decompres- Recommended least invasive op for patients w/ sion instrumented fusion). Used unique outcome measure. 2 subgroups compared based on length of preop shorter duration of symptoms. Longer would sugsymptoms. Patients w/ shorter duration of symptoms did better w/ decompression alone; those w/ longer du- gest instrumentation (p 0.05). ration of symptoms did better w/ decompression instrumented fusion. At 8 yrs: decompression alone best. Continued 688

4 Spinal stenosis without spondylolisthesis TABLE 1 Continued Authors & Year Class Description Comment Gibson, et al., 1999 III Cochrane review of 14 RCTs for DS/stenosis. 3 of the identified RCTs analyzed adjunct fusion w/ 139 patients No difference btwn laminect fusion vs laminect total w/ 99% FU at 2 3 yrs. only when combined analysis of 3 RCTs performed (OR 0.8, 95% CI ). Katz, et al., 1999 III 199 of 305 patients sent questionnaire 2 yrs postop replied. Patients were treated w/ laminect only (138), lamin- Recommendation for surgery was strong. ect in situ fusion (31), or laminect instrumented fusion (30). Fusion cases had better outcome; no difference btwn instrumented & noninstrumented groups. Rompe, 1999 III Retrospective review of 117 consecutive patients divided into 3 groups: laminect & undercutting decompres- Main conclusion was that good results are achieved sion (39), laminect w/ foraminotomies (n = 51), & decompression & fusion (27). 8-yr FU. Walking capacity w/ various ops but that the benefits of op decline (p 0.001) & pain (p 0.01) improved in all groups; however, improvements declined over time. over time. Vitaz, et al., 1999 III Retrospective review of 65 patients: 21% laminect, 79% laminect/fusion. Specifically looked at older (age 75 No comparison btwn groups. yrs). Fused patients w/ 50% facet removal, severe LBP, instability, or listhesis. Good clinical outcomes achieved in 89 90%; 96% fusion rate. Yone & Sakou, 1999 III Retrospective. Extension of prior paper. 60 patients: 33 unstable (19 fused, 14 only laminect) & 22 stable by Patients w/ unstable fusion had similar outcomes flex ext criteria. Again, good results for laminect only in stable group & laminect fusion in patients w/ de- to those w/o instability treated w/ decompression formity or instability. alone. Cornefjord, et al., 2000 III Retrospective review of 124 patients. 96 available for FU. Independent questionnaires. Parameters: satisfaction, No statistical differences btwn those fused or not LBP, leg pain, & walking capacity. Op benefited all parameters especially walking by 50% (p 0.001) & fused. No difference btwn treatment w/ instruleg back pain (p 0.001). Long FU, 7.1 yrs. Overall 65% reported satisfaction. 42 had instrumented PLF. mented vs noninstrumented fusion. 17 had only in situ fusions. Fusion based on preop deformity or iatrogenic instability. Jolles, et al., 2001 III Retrospective review of 155 patients, 77 had 6.5-yr FU. Roland & Prolo scales used. 79% had decrease in pain 9% of patients w/o preop evidence of instability went w/ excellent outcomes. 9% had delayed slip. 12 w/ fusion who had preop evidence of instability had no delayed slips. on to have delayed slip after laminect w/o fusion. Sheehan, et al., 2001 III Topic review authors concluded that there is no benefit derived from the addition of fusion to decompression Topic review. alone in the absence of segmental instability. Instrumentation was recommended only for scoliosis or severe slips w/ high risk of progression. Other indications for fusion included scoliosis, 50% facet resection, or listhesis. * CI = confidence interval; DS = degenerative spondylolisthesis; flex ext = flexion extension; FU = follow up; JOA = Japanese Orthopaedic Association; laminect = laminectomy; LBP = low-back pain; listhesis = spondylolisthesis; OR = odds ratio; PLIF = posterior lumbar interbody fusion. formed in 58 patients. He reported an overall good outcome rate of 70%. There was a trend toward better results with fusion in patients with spondylolisthesis, scoliosis, severely degenerated facet joints, collapsed disc spaces, and preoperative movement noted on dynamic spinal radiographs. These trends, however, did not achieve statistical significance, even in the subgroup in which these identified risk factors were present. All of the aforementioned papers provide Class III medical evidence suggesting that PLF is not necessary or beneficial in the majority of patients undergoing decompression for symptomatic lumbar stenosis without deformity or instability. Because of the retrospective nature of all of these studies, the fact that patient selection criteria for fusion compared with no fusion were not standardized, and the relatively small number of patients involved in each study, definitive conclusions regarding the role of fusion in this patient population cannot be made. Fox, et al., 8 performed a retrospective analysis of 124 patients they had treated for symptomatic lumbar stenosis. They observed that 91% of those who had undergone laminectomy and fusion reported good outcomes compared to 75% of those treated with laminectomy alone. The majority of patients selected for fusion were reported to have preoperative instability or spondylolisthesis. Only two patients without instability or spondylolisthesis underwent fusion. Their mean follow-up duration was 5.8 years; they were administered a patient satisfaction survey. This paper provides Class III medical evidence supporting the use of lumbar fusion in patients with lumbar stenosis, particularly those with evidence of preoperative instability. Herkowitz and Kurz 11 alternately assigned a group of 50 patients with stenosis and varying degrees of spondylolisthesis to laminectomy alone or laminectomy combined with in situ noninstrumented fusion (25 patients in each group). Fusion-treated patients fared much better than those treated with laminectomy alone at the 2.4-year follow up in terms of satisfaction and pain control (visual analog scale, p ). Progressive spondylolisthesis and segmental vertebral angulation were noted more frequently in the laminectomy-alone group and were associated with poor outcomes. This paper provides Class II medical evidence that the addition of a noninstrumented fusion improves outcomes in patients with lumbar stenosis and spondylolisthesis. In terms of patients without preoperative deformity or instability, this paper provides Class III medical evidence in favor of the addition of fusion at the time of decompression in that poor outcomes were associated with late-onset deformity. Katz, et al., 16 reported on 272 patients who had undergone treatment for lumbar stenosis. In a multicenter retrospective trial, 71% of patients were treated with laminectomy alone and 29% with instrumented/noninstrumented fusion. At 6 months, the authors observed that fusiontreated patients fared better with regard to back pain scores (p 0.004) and walking tolerance (p 0.05), but this benefit deteriorated by the time of the 24-month follow up (p 0.01 low-back pain; p 0.09 walk tolerance). For the subset of patients with preoperative spondylolisthesis or scoliosis, the benefit of fusion was statistically significant and more stable over time (p ). In a different prospective nonrandomized observational trial, Katz, et al., 17 reported a similar benefit of 689

5 D. K. Resnick, et al. fusion in 199 patients with lumbar stenosis, 61 of whom were treated with fusion (31 in situ and 30 instrumented). These two studies provide Class III medical evidence in support of a beneficial effect derived from adding fusion at the time of decompression in patients with stenosis and concomitant spinal deformity. Gibson, et al., 9 performed a metaanalysis on the subject of spinal stenosis for the Cochrane review. They identified three RCTs with a total of 139 patients; 99% of patients were available for follow up at 2 to 3 years (these studies have been discussed in previous paragraphs). 2,10,11 In their metaanalysis Gibson and colleagues concluded that no significant benefit existed for lumbar fusion in the treatment of patients with lumbar stenosis (odds ratio 0.8, 95% confidence interval ). The rationale used to justify the combined analysis of these studies with disparate patient populations (for example, Grob, et al., 10 and Bridwell, et al., 2 treated completely different patient populations) is not well described. Turner, et al., 29 attempted a separate metaanalysis regarding this issue and concluded that the medical evidence available from the 74 papers they reviewed could not be combined to provide definitive conclusions regarding the use of fusion as an adjunct in the treatment of patients with lumbar stenosis. They reported that the primary problem was the heterogeneous outcome measures utilized among the different patient series. A third metaanalysis performed on this subject revealed the potential influence of symptom duration. Niggemeyer, et al., 22 demonstrated that among patients with symptoms of less than 8 years duration, decompression alone yielded the best outcomes; however, in patients with symptoms of stenosis for longer than 15 years duration, instrumentation-augmented fusion and decompression yielded the best results (p 0.05). Because of the previously cited difficulty in combining data from different studies involving different outcome measures, these observations must be considered with caution. Several retrospective series were identified that describe the results of various procedures for instrumented spinal fusion in addition to decompression for spinal stenosis in patients without deformity. 5,23 For example, Conley, et al., 5 retrospectively reviewed the use of Knodt rods as a routine adjunct to decompression in patients with stenosis and reported a 66% excellent outcome rate and a 72% radiographic fusion rate. In general, these series offer little insight into the advantage of adding modern segmental instrumentation to a PLF during the treatment of lumbar stenosis. A few series have compared the use of instrumented fusion and decompression with lumbar decompression alone. Louis and Nazarian 18 summarized their experience with 350 patients of whom nearly 34% underwent fusion supplemented with pedicle screw fixation in addition to decompression in patients with preoperative spondylolisthesis or instability, and in cases in which a wide decompression was accomplished. In terms of lumbar pain, they were able to demonstrate a trend toward better outcomes in patients treated with decompression and pedicle screw augmented fusion (85%) compared with those who underwent decompression alone (65%). No patient underwent noninstrumented fusion in this cohort. Yone, et al., 31,32 performed a retrospective analysis of 60 patients with lumbar stenosis. Thirty-three patients were identified as having preoperative spinal instability based on lateral flexion extension radiography. Three groups were assessed: patients with stenosis and instability treated with laminectomy and instrumented fusion (some pedicle screws and some Knodt rods), those with stenosis and instability treated with laminectomy alone, and those with stenosis and no instability treated with laminectomy alone. In patients with stenosis and instability, improvements in low-back pain outcomes were significantly greater (p 0.05) in the fusion group. The authors observed similar rates of good outcomes (80%) among fusion-treated patients with preoperative instability or deformity and those without instability or deformity who underwent decompression alone. Cornefjord, et al., 6 performed a retrospective review of 124 patients who underwent surgery for lumbar stenosis. Fiftynine patients underwent fusion, of whom 42 also received supplemental pedicle screw instrumention. No differences were observed between patients in the fusion and nonfusion groups or between patients in the instrumentation-augmented fusion group and those in the noninstrumented fusion group. Because of differences in selection criteria for instrumentation, the use of nonvalidated outcome measures, and the retrospective nature of these reports, all of their medical evidence regarding the use of supplemental instrumentation for PLF following decompression in patients with lumbar stenosis and without deformity is considered Class III. Summary Based on the medical evidence derived from the scientific literature on this topic, there does not appear to be evidence to support the hypothesis that fusion (with or without instrumentation) provides any benefit over decompression alone in the treatment of lumbar stenosis in patients in whom there is no evidence of preoperative deformity or instability. A single report provides Class II medical evidence and several papers provide Class III medical evidence suggesting that the addition of fusion to decompression in patients with lumbar stenosis and instability evidenced by movement on preoperative flexion extension radiographs does improve outcome. There are also reports (Class III medical evidence) indicating that patients with lumbar stenosis, without deformity or instability, treated with wide decompression or facetectomy may suffer iatrogenic lumbar instability. Fusion in these patients may improve outcome. There is conflicting Class III medical evidence regarding the application of instrumentation in addition to PLF in patients treated for lumbar stenosis without deformity or preoperative instability. Future Research Directions Clinical outcome in patients without deformity or instability undergoing decompression for lumbar stenosis should be radiographically confirmed in patients with and without evidence of instability on preoperative x-ray films. Such patients could be randomized into fusion or nonfusion groups, thus allowing accrual of Class I evidence to support or refute the hypothesis that the added expense, operative time, and increased morbidity associated with fusion is justified by a clinical benefit. The study should use validated 690

6 Spinal stenosis without spondylolisthesis clinical outcome measures for both decompression- (such as walking tolerance) and fusion- (such as back pain and disability scales) related outcomes. If the value of fusion is convincingly demonstrated, then the issue of supplemental internal fixation can be addressed. References 1. Benz R, Garfin S: Current techniques of decompression of the lumbar spine. Clin Orthop Relat Res 384:75 81, Bridwell K, Sedgewick TA, O Brien MF, et al: The role of fusion and instrumentation in the treatment of degenerative spondylolisthesis with spinal stenosis. J Spinal Disord 6: , Brunon J, Chazal J, Chirossel J, et al: When is spinal fusion warranted in degenerative lumbar spinal stenosis? Rev Rhum Engl Ed 63:44 50, Caputy A, Luessenhop A: Long-term evaluation of decompressive surgery for degenerative lumbar stenosis. J Neurosurg 77: , Conley F, Cady C, Lieberson R: Decompression of lumbar spinal stenosis and stabilization with Knodt rods in the elderly patient. Neurosurgery 26: , Cornefjord M, Byrod G, Brisby H, et al: A long-term (4- to 12- year) follow-up study of surgical treatment of lumbar spinal stenosis. Eur Spine J 9: , DiPierro C, Helm G, Shaffrey C, et al: Treatment of lumbar spinal stenosis by extensive unilateral decompression and contralateral autologous bone fusion: operative technique and results. J Neurosurg 84: , Fox MW, Onofrio BM, Onofrio BM, et al: Clinical outcomes and radiological instability following decompressive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone. J Neurosurg 85: , Gibson J, Grant I, Waddell G: The Cochrane review of surgery for lumbar disc prolapse and degenerative lumbar spondylosis. Spine 24: , Grob D, Humke T, Dvorak J: Degenerative lumbar spinal stenosis: decompression with and without arthrodesis. J Bone Joint Surg Am 77: , Herkowitz H, Kurz L: Degenerative lumbar spondylolisthesis with spinal stenosis. J Bone Joint Surg 73: , Herron L, Mangelsdorf C: Lumbar spinal stenosis: results of surgical treatment. J Spinal Disord 4:23 33, Hopp E, Tsou P: Postdecompression lumbar instability. Clin Orthop Relat Res 227: , Hutter C: Spinal stenosis and posterior lumbar interbody fusion. Clin Orthop Relat Res 193: , Jolles B, Porchet F, Theumann N: Surgical treatment of lumbar spinal stenosis. Five-year follow-up. J Bone Joint Surg Br 87: , Katz J, Lipson S, Lew R, et al: Lumbar laminectomy alone or with instrumented or noninstrumented arthrodesis in degenerative lumbar spinal stenosis. Patient selection, costs, and surgical outcomes. Spine 22: , Katz J, Stucki G, Lipson S, et al: Predictors of surgical outcome in degenerative lumbar spinal stenosis. Spine 24: , Louis R, Nazarian S: Lumbar stenosis surgery: the experience of the orthopaedic surgeon. Chir Organi Mov 77:23 29, Nasca R: Lumbar spinal stenosis: surgical considerations. J South Orthop Assoc 11: , Nasca R: Rationale for spinal fusion in lumbar spinal stenosis. Spine 14: , Nasca R: Surgical management of lumbar spinal stenosis. Spine 12: , Niggemeyer O, Strauss J, Schulitz K: Comparison of surgical procedures for degenerative lumbar spinal stenosis: a metaanalysis of the literature from 1975 to Eur Spine J 6: , Ray C: Transfacet decompression with dowel fixation: a new technique for lumbar lateral spinal stenosis. Acta Neurochir Suppl 43:48 54, Rompe J, Eysel P, Zollner J, et al: Degenerative lumbar spinal stenosis. Long-term results after undercutting decompression compared with decompressive laminectomy alone or with instrumented fusion. Neurosurg Rev 22: , Sheehan J, Shaffrey C, Jane JA Sr: Degenerative lumbar stenosis: the neurosurgical perspective. Clin Orthop Relat Res 384: 61 74, Shenkin H, Hash C: Spondylolisthesis after multiple bilateral laminectomies and facetectomies for lumbar spondylosis. J Neurosurg 50:45 47, Sonntag V, Marciano F: Is fusion indicated for lumbar spinal disorders? Spine 20 (24 Suppl):S138 S142, Tile M, McNeil S, Zarins R, et al: Spinal stenosis. Results of treatment. Clin Orthop Relat Res 115: , Turner J, Ersek M, Herron L, et al: Surgery for lumbar spinal stenosis. Attempted meta-analysis of the literature. Spine 17: 1 8, Vitaz T, Raque G, Shields C, et al: Surgical treatment of lumbar spinal stenosis in patients older than 75 years of age. J Neurosurg (Spine 2) 91: , Yone K, Sakou T: Usefulness of Posner s definition of spinal instability for selection of surgical treatment for lumbar spinal stenosis. J Spinal Disord 12:40 44, Yone K, Sakou T, Kawauchi Y, et al: Indication of fusion for lumbar spinal stenosis in elderly patients and its significance. Spine 21: , 1996 Manuscript received December 7, Accepted in final form April 11, Address reprint requests to: Daniel K. Resnick, M.D., Department of Neurological Surgery, University of Wisconsin Medical School, K4/834 Clinical Science Center, 600 Highland Avenue, Madison, Wisconsin Resnick@neurosurg.wisc.edu. 691