A clinical study of degenerative spondylolisthesis. Radiographic analysis and choice of treatment

Degenerative lumbar spondylolisthesis: review of current classifications and proposal of a novel classification system

PURPOSE

To review existing classification systems for degenerative spondylolisthesis (DS), propose a novel classification designed to better address clinically relevant radiographic and clinical features of disease, and determine the inter- and intraobserver reliability of this new system for classifying DS.

METHODS

The proposed classification system includes four components: 1) segmental dynamic instability, 2) location of spinal stenosis, 3) sagittal alignment, and 4) primary clinical presentation. To establish the reliability of this system, 12 observers graded 10 premarked test cases twice each. Kappa values were calculated to assess the inter- and intraobserver reliability for each of the four components separately.

RESULTS

Interobserver reliability for dynamic instability, location of stenosis, sagittal alignment, and clinical presentation was 0.94, 0.80, 0.87, and 1.00, respectively. Intraobserver reliability for dynamic instability, location of stenosis, sagittal alignment, and clinical presentation were 0.91, 0.88, 0.87, and 0.97, respectively.

CONCLUSION

The UCSF DS classification system provides a novel framework for assessing DS based on radiographic and clinical parameters with established implications for surgical treatment. The almost perfect interobserver and intraobserver reliability observed for all components of this system demonstrates that it is simple and easy to use. In clinical practice, this classification may allow subclassification of similar patients into groups that may benefit from distinct treatment strategies, leading to the development of algorithms to help guide selection of an optimal surgical approach. Future work will focus on the clinical validation of this system, with the goal of providing for more evidence-based, standardized approaches to treatment and improved outcomes for patients with DS.

Radiographic and Clinical Outcomes After Stand-Alone Anterior Lumbar Interbody Fusion for Symptomatic L5-S1 Retrolisthesis

BACKGROUND AND OBJECTIVES

Degenerative lumbar spondylolisthesis is associated with significant pain and disability. The literature on the treatment options and clinical outcomes for lumbar anterolisthesis is robust, but very few reports specifically evaluate lumbar retrolisthesis. This study investigated surgical outcomes for symptomatic L5-S1 retrolisthesis treated with stand-alone L5-S1 anterior lumbar interbody fusion (ALIF).

METHODS

All patients with symptomatic L5-S1 retrolisthesis treated with stand-alone L5-S1 ALIF at a single institution over a 7-year period were identified. Exhaustive nonoperative management had failed for all patients. Patients with previous lumbar fusion were excluded. Preoperative and postoperative radiographic images and patient-reported outcome measures for 20 patients (14 males and 6 females; mean [SD] age, 50.3 [13.7] years) were analyzed.

RESULTS

The mean (SD) follow-up was 43.0 (23.7) months (range, 12.1-102.5 months). Patients experienced postoperative improvements in L5-S1 retrolisthesis (P = .048), L5-S1 disk height and angle (P < .001), L5 foraminal height (P < .001), L5-S1 lordosis (P < .001), and lumbar lordosis (P = .01). There were no significant changes in spinopelvic parameters. At the most recent follow-up, minimal clinically important differences in Oswestry Disability Index score, 36-Item Short-Form Survey (SF-36), and numerical rating scale score for leg pain were achieved in 11 of 20 (55%), 7 of 14 (50%), and 7 of 13 (54%) patients, respectively. All patients demonstrated fusion with no graft subsidence at up to 32 months. No patient experienced intraoperative complications, was readmitted, or required a subsequent posterior decompression or fusion because of refractory symptoms.

CONCLUSION

In our cohort, stand-alone L5-S1 ALIF was associated with radiographic and clinical improvement in patients with symptomatic L5-S1 retrolisthesis.

Sequential MRI Changes After Lateral Lumbar Interbody Fusion in Spondylolisthesis with Mild and Severe Lumbar Spinal Stenosis

OBJECTIVE

We assessed the sequential magnetic resonance imaging changes of indirect neural decompression after minimally invasive lumbar lateral interbody fusion (LIF) combined with posterior percutaneous pedicle screw (PPS) fixation for degenerative spondylolisthesis (DS) according to the severity of preoperative lumbar spinal stenosis.

METHODS

A total of 43 patients (mean age, 68.7 years; 16 men and 27 women) with DS who had undergone LIF and closed reduction with PPS fixation were enrolled. The intervertebral levels were divided into the moderate stenosis (MS) group (preoperative cross-sectional area [CSA] of the thecal sac >50 mm²) and severe stenosis (SS) group (CSA ≤50 mm²). The CSA, ligamentum flavum thickness, and diameter of the thecal sac at the affected level were measured on cross-sectional magnetic resonance images at baseline, immediately postoperatively, and 2 years postoperatively.

RESULTS

For the 31 and 29 intervertebral levels in the MS and SS groups, the mean CSA at baseline, immediately postoperatively, and 2 years postoperatively was 76.9 mm² and 35.8 mm², 104.3 mm² and 81.4 mm², and 130.9 mm² and 105.7 mm², respectively. The mean ligamentum flavum thicknesses at 2 years postoperatively became thinner than that immediately after surgery in both groups (P < 0.01). The mean diameter of the thecal sac at 2 years was longer than that immediately after surgery in both groups (MS group, P < 0.05; SS group, P < 0.01) The expansion ratio of the CSA at 2 years postoperatively was significantly greater in the SS group than that in the MS group (P < 0.01).

CONCLUSIONS

Sequential enlargement of the spinal canal was obtained by the thinning of the ligamentum flavum after LIF and PPS fixation in patients with DS with both mild and severe stenosis. The effect of indirect neural decompression was equivalent even in those with severe lumbar spinal stenosis.

Contraindication of Minimally Invasive Lateral Interbody Fusion for Percutaneous Reduction of Degenerative Spondylolisthesis: A New Radiographic Indicator of Bony Lateral Recess Stenosis Using I Line

Study Design

Retrospective cohort study.

Purpose

This study aimed to evaluate aggravated lateral recess stenosis and clarify the indirect decompression threshold by combined lateral interbody fusion and percutaneous pedicle screw fixation (LIF/PPS).

Overview of Literature

No previous reports have described an effective radiographic indicator for determining the surgical indication for LIF/PPS.

Methods

A retrospective review of 185 consecutive patients, who underwent 1- or 2-level lumbar fusion surgery for degenerative spondylolisthesis (DS). According to their symptomatic improvement, they were placed into either the “recovery” or “no-recovery” group. Preoperative computed tomography (CT) images were evaluated for the position of the superior articular processes at the slipping level, followed by a graded classification (grades 0–3) using the impingement line (I line), a new radiographic indicator. All 432 superior articular facets in 216 slipped levels were classified, and both groups’ characteristics were compared.

Results

There were 171 patients (92.4%) in the recovery group and 14 patients in the no-recovery group (7.6%). All patients in the no-recovery group were diagnosed with symptoms associated with deteriorated bony lateral recess stenosis. All superior articular processes of the lower vertebral body in affected levels reached and exceeded the I line (I line-; grade 2 and 3) on preoperative sagittal CT images. In the recovery group, most superior articular processes did not reach the I line (I line+; grade 0 and 1; p=0.0233).

Conclusions

In DS cases that are classified as grade 2 or greater, the risk of aggravated bony lateral recess stenosis due to corrective surgery is high; therefore, indirect decompression by LIF/PPS is, in principle, contraindicated.

Management of symptomatic degenerative low-grade lumbar spondylolisthesis

Degenerative low-grade lumbar spondylolisthesis is the most common form of spondylolisthesis.

The majority of patients are asymptomatic and do not require surgical intervention.

Symptomatic patients present with a combination of lower back pain, radiculopathy and/or neurogenic claudication and may warrant surgery if non-operative measures fail.

There is widespread controversy regarding the indications for surgery and appropriate treatment strategies for patients with this type of spondylolisthesis.

This article provides a comprehensive evidence-based review of the available literature to support the management of degenerative low-grade spondylolisthesis.

Cite this article: EFORT Open Rev 2018;3:620-631. DOI: 10.1302/2058-5241.3.180020.

Stand-alone anterior lumbar interbody fusion: indications, techniques, surgical outcomes and complications

INTRODUCTION

Anterior lumbar interbody fusion (ALIF) is a well-established technique to achieve lumbar spine fusion with various indications including degenerative disk disease, spondylolisthesis, recurrent disk herniation, adjacent level disease, pseudoarthrosis, as well as being used as part of the overall strategy to restore sagittal balance. ALIF can be an extremely useful tool in any spine surgeon's armamentarium. However, like any surgical procedure, proper patient selection is key to success. A solid understanding of the biomechanics, careful surgical planning, along with clear knowledge of the advantages and disadvantages of stand-alone ALIF will ensure optimal clinical outcome. Stand-alone ALIF may be a suitable surgical option in carefully selected patients that can provide good clinical results and adequate fusion rates without the need for posterior instrumentation. Areas covered: A brief overview of the indications, techniques, biomechanics, surgical outcome and complications of stand-alone ALIF is provided in this article with a review of the pertinent literature. Expert commentary: In this review we discuss the clinical evidence of using a stand-alone ALIF compared to other fusion techniques of the lumbar spine. The development of interbody cages with integrated screws has increased the arthrodesis rate and improved clinical outcomes while decreasing morbidity and operative time.

RNA Sequencing Reveals a Role of TonEBP Transcription Factor in Regulation of Pro-inflammatory Genes in Response to Hyperosmolarity in Healthy Nucleus Pulposus Cells: A HOMEOSTATIC RESPONSE?

Transcription factor tonicity-responsive enhancer-binding protein (TonEBP/NFAT5) is critical for osmo-adaptation and extracellular matrix homeostasis of nucleus pulposus (NP) cells in their hypertonic tissue niche. Recent studies implicate TonEBP signaling in inflammatory disease and rheumatoid arthritis pathogenesis. However, broader functions of TonEBP in the disc remain unknown. RNA sequencing was performed on NP cells with TonEBP knockdown under hypertonic conditions. 1140 TonEBP-dependent genes were identified and categorized using Ingenuity Pathway Analysis. Bioinformatic analysis showed enrichment of matrix homeostasis and cytokine/chemokine signaling pathways. C-C motif chemokine ligand 2 (CCL2), interleukin 6 (IL6), tumor necrosis factor (TNF), and nitric oxide synthase 2 (NOS2) were studied further. Knockdown experiments showed that TonEBP was necessary to maintain expression levels of these genes. Gain- and loss-of-function experiments and site-directed mutagenesis demonstrated that TonEBP binding to a specific site in the CCL2 promoter is required for hypertonic inducibility. Despite inhibition by dominant-negative TonEBP, IL6 and NOS2 promoters were not hypertonicity-inducible. Whole-disc response to hypertonicity was studied in an ex vivo organ culture model, using wild-type and haploinsufficient TonEBP mice. Pro-inflammatory targets were induced by hypertonicity in discs from wild-type but not TonEBP-haploinsufficient mice. Mechanistically, NF-κB activity increased with hypertonicity and was necessary for hypertonic induction of target genes IL6, TNF, and NOS2 but not CCL2 Although TonEBP maintains transcription of genes traditionally considered pro-inflammatory, it is important to note that some of these genes also serve anabolic and pro-survival roles. Therefore, in NP cells, this phenomenon may reflect a physiological adaptation to diurnal osmotic loading of the intervertebral disc.

Surgical options for lumbar spinal stenosis

BACKGROUND

Hospital charges for lumbar spinal stenosis have increased significantly worldwide in recent times, with great variation in the costs and rates of different surgical procedures. There have also been significant increases in the rate of complex fusion and the use of spinal spacer implants compared to that of traditional decompression surgery, even though the former is known to incur costs up to three times higher. Moreover, the superiority of these new surgical procedures over traditional decompression surgery is still unclear.

OBJECTIVES

To determine the efficacy of surgery in the management of patients with symptomatic lumbar spinal stenosis and the comparative effectiveness between commonly performed surgical techniques to treat this condition on patient-related outcomes. We also aimed to investigate the safety of these surgical interventions by including perioperative surgical data and reoperation rates.

SEARCH METHODS

Review authors performed electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED, Web of Science, LILACS and three trials registries from their inception to 16 June 2016. Authors also conducted citation tracking on the reference lists of included trials and relevant systematic reviews.

SELECTION CRITERIA

This review included only randomised controlled trials that investigated the efficacy and safety of surgery compared with no treatment, placebo or sham surgery, or with another surgical technique in patients with lumbar spinal stenosis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the studies for inclusion and performed the 'Risk of bias' assessment, using the Cochrane Back and Neck Review Group criteria. Reviewers also extracted demographics, surgery details, and types of outcomes to describe the characteristics of included studies. Primary outcomes were pain intensity, physical function or disability status, quality of life, and recovery. The secondary outcomes included measurements related to surgery, such as perioperative blood loss, operation time, length of hospital stay, reoperation rates, and costs. We grouped trials according to the types of surgical interventions being compared and categorised follow-up times as short-term when less than 12 months and long-term when 12 months or more. Pain and disability scores were converted to a common 0 to 100 scale. We calculated mean differences for continuous outcomes and relative risks for dichotomous outcomes. We pooled data using the random-effects model in Review Manager 5.3, and used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We included a total of 24 randomised controlled trials (reported in 39 published research articles or abstracts) in this review. The trials included 2352 participants with lumbar spinal stenosis with symptoms of neurogenic claudication. None of the included trials compared surgery with no treatment, placebo or sham surgery. Therefore, all included studies compared two or more surgical techniques. We judged all trials to be at high risk of bias for the blinding of care provider domain, and most of the trials failed to adequately conceal the randomisation process, blind the participants or use intention-to-treat analysis. Five trials compared the effects of fusion in addition to decompression surgery. Our results showed no significant differences in pain relief at long-term (mean difference (MD) -0.29, 95% confidence interval (CI) -7.32 to 6.74). Similarly, we found no between-group differences in disability reduction in the long-term (MD 3.26, 95% CI -6.12 to 12.63). Participants who received decompression alone had significantly less perioperative blood loss (MD -0.52 L, 95% CI -0.70 L to -0.34 L) and required shorter operations (MD -107.94 minutes, 95% CI -161.65 minutes to -54.23 minutes) compared with those treated with decompression plus fusion, though we found no difference in the number of reoperations (risk ratio (RR) 1.25, 95% CI 0.81 to 1.92). Another three trials investigated the effects of interspinous process spacer devices compared with conventional bony decompression. These spacer devices resulted in similar reductions in pain (MD -0.55, 95% CI -8.08 to 6.99) and disability (MD 1.25, 95% CI -4.48 to 6.98). The spacer devices required longer operation time (MD 39.11 minutes, 95% CI 19.43 minutes to 58.78 minutes) and were associated with higher risk of reoperation (RR 3.95, 95% CI 2.12 to 7.37), but we found no difference in perioperative blood loss (MD 144.00 mL, 95% CI -209.74 mL to 497.74 mL). Two trials compared interspinous spacer devices with decompression plus fusion. Although we found no difference in pain relief (MD 5.35, 95% CI -1.18 to 11.88), the spacer devices revealed a small but significant effect in disability reduction (MD 5.72, 95% CI 1.28 to 10.15). They were also superior to decompression plus fusion in terms of operation time (MD 78.91 minutes, 95% CI 30.16 minutes to 127.65 minutes) and perioperative blood loss (MD 238.90 mL, 95% CI 182.66 mL to 295.14 mL), however, there was no difference in rate of reoperation (RR 0.70, 95% CI 0.32 to 1.51). Overall there were no differences for the primary or secondary outcomes when different types of surgical decompression techniques were compared among each other. The quality of evidence varied from 'very low quality' to 'high quality'.

AUTHORS' CONCLUSIONS

The results of this Cochrane review show a paucity of evidence on the efficacy of surgery for lumbar spinal stenosis, as to date no trials have compared surgery with no treatment, placebo or sham surgery. Placebo-controlled trials in surgery are feasible and needed in the field of lumbar spinal stenosis. Our results demonstrate that at present, decompression plus fusion and interspinous process spacers have not been shown to be superior to conventional decompression alone. More methodologically rigorous studies are needed in this field to confirm our results.

Acquired Degenerative Changes of the Intervertebral Segments at and Supradjacent to the Lumbosacral Junction

In earlier evolutionary times, mammals were primarily quadrupeds, although other bipeds have been represented during the course of the Earth's several billion-year history. In many cases, either the bipedal stance yielded a large tail and hypoplastic upper extremities (e.g., Tyrannosaurus rex, the kangaroo), or it culminated in hypoplasia of the tail and further development and specialization of the upper extremities (e.g., nonhuman primates and human beings). In the human species this relatively recently acquired posture resulted in a more or less pronounced lumbosacral lordosis. In turn, certain compensatory anatomic features have since occurred. These include the normal characteristic posteriorly directed wedge-shape of the L5 vertebral body and the L5-S1 intervertebral disc; the L4 vertebral body and the L4-L5 and L3-4 disc may be similarly visibly affected.

These compensatory mechanisms, however, have proved to be functionally inadequate over the present long-term of the human life span. Upright posture leads to increased weight bearing in humans that progressively causes excess stresses at and suprajacent to the lumbosacral junction. These combined factors result in accelerated aging and degenerative changes and a predisposition to frank biomechanical failure of the subcomponents of the spinal column in these spinal segments.

One other specific problem that occurs at the lumbosacral junction that predisposes toward premature degeneration is the singular relationship that exists between a normally mobile segment of spine (i.e., the lumbar spine), and a normally immobile one (i.e., the sacrum). It is well known that mobile spinal segments adjacent to congenitally or acquired fused segments have a predilection toward accelerated degenerative changes. The only segment of the spine in which this is invariably normally true is at the lumbosacral junction (i.e., the unfused lumbar spine adjoining the fused sacrum).

Nevertheless, biomechanical failures of the human spine are not lethal traits; in most cases today, mankind reaches sexual maturity before spinal biomechanical failure precludes sexual reproduction. For this gene-preserving reason, degenerative spinal disorders will likely be a part of modern societies for the foreseeable eternity of the race.

The detailed alterations accruing from the interrelated consequences of and phenomena contributing to acquired degenerative changes of the lumbosacral intervertebral segments as detailed in this discussion highlight the extraordinary problems that are associated with degenerative disease in this region of the spine. Further clinicoradiologic research in this area will progressively determine the clinical applications and clinical efficacy of the various traditional and newer methods of therapy in patients presenting with symptomatic acquired collapse of the intervertebral discs at and suprajacent to the lumbosacral junction and the interrelated degenerative alterations of the nondiscal structures of the spine.

Guideline summary review: An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spondylolisthesis

BACKGROUND CONTEXT

The North American Spine Society's (NASS) Evidence-Based Clinical Guideline for the Diagnosis and Treatment of Degenerative Lumbar Spondylolisthesis features evidence-based recommendations for diagnosing and treating degenerative lumbar spondylolisthesis. The guideline updates the 2008 guideline on this topic and is intended to reflect contemporary treatment concepts for symptomatic degenerative lumbar spondylolisthesis as reflected in the highest quality clinical literature available on this subject as of May 2013. The NASS guideline on this topic is the only guideline on degenerative lumbar spondylolisthesis included in the Agency for Healthcare Research and Quality's National Guideline Clearinghouse (NGC).

PURPOSE

The purpose of this guideline is to provide an evidence-based educational tool to assist spine specialists when making clinical decisions for patients with degenerative lumbar spondylolisthesis. This article provides a brief summary of the evidence-based guideline recommendations for diagnosing and treating patients with this condition.

STUDY DESIGN

A systematic review of clinical studies relevant to degenerative spondylolisthesis was carried out.

METHODS

This NASS spondyolisthesis guideline is the product of the Degenerative Lumbar Spondylolisthesis Work Group of NASS' Evidence-Based Guideline Development Committee. The methods used to develop this guideline are detailed in the complete guideline and technical report available on the NASS website. In brief, a multidisciplinary work group of spine care specialists convened to identify clinical questions to address in the guideline. The literature search strategy was developed in consultation with medical librarians. Upon completion of the systematic literature search, evidence relevant to the clinical questions posed in the guideline was reviewed. Work group members used the NASS evidentiary table templates to summarize study conclusions, identify study strengths and weaknesses, and assign levels of evidence. Work group members participated in webcasts and in-person recommendation meetings to update and formulate evidence-based recommendations and incorporate expert opinion when necessary. The draft guidelines were submitted to an internal peer review process and ultimately approved by the NASS Board of Directors. Upon publication, the Degenerative Lumbar Spondylolisthesis guideline was accepted into the NGC and will be updated approximately every 5 years.

RESULTS

Twenty-seven clinical questions were addressed in this guideline update, including 15 clinical questions from the original guideline and 12 new clinical questions. The respective recommendations were graded by strength of the supporting literature, which was stratified by levels of evidence. Twenty-one new or updated recommendations or consensus statements were issued and 13 recommendations or consensus statements were maintained from the original guideline.

CONCLUSIONS

The clinical guideline was created using the techniques of evidence-based medicine and best available evidence to aid practitioners in the care of patients with degenerative lumbar spondylolisthesis. The entire guideline document, including the evidentiary tables, literature search parameters, literature attrition flow chart, suggestions for future research, and all of the references, is available electronically on the NASS website at https://www.spine.org/Pages/ResearchClinicalCare/QualityImprovement/ClinicalGuidelines.aspx and will remain updated on a timely schedule.

Degenerative Spondylolisthesis: An Analysis of the Nationwide Inpatient Sample Database

STUDY DESIGN

Analysis of the Nationwide Inpatient Sample database.

OBJECTIVE

To investigate national trends, risks, and benefits of surgical interventions for degenerative spondylolisthesis (DS).

SUMMARY OF BACKGROUND DATA

The surgical management of DS continues to evolve whereas the most clinically and cost-effective treatment is debated. With an aging US population and growing restraints on a financially burdened health care system, a clear understanding of national trends in the surgical management of DS is needed.

METHODS

The Nationwide Inpatient Sample database was queried for patients with DS undergoing lumbar fusions from 2001 to 2010, using International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and procedure codes. Analyses compared instrumented posterolateral fusion (PLF), posterolateral fusion with anterior lumbar interbody fusion (ALIF + PLF), PLF with posterior interbody fusion (P/TLIF + PLF), anterior instrumented interbody fusion (ALIF), and posterior interbody fusion with posterior instrumentation (P/TLIF). Clinical data were analyzed representing the initial acute phase care after surgery.

RESULTS

There were 48,911 DS surgical procedures identified, representing 237,383 procedures. The percentage of patients undergoing PLF, ALIF + PLF, or ALIF increased whereas the percentage of P/TLIF or P/TLIF + PLF decreased over time. Total charges were less (P < 0.001), average length of hospital stay was shorter (P < 0.01), and average age was older (P < 0.01) for patients who underwent PLF compared with any other procedure. Type of procedure varied on the basis of the geographic region of the hospital, teaching versus nonteaching hospital, and size of hospital (P < 0.01). Patients who had P/TLIF + PLF or ALIF had a higher risk of mortality than patients who had PLF (odds ratios: 5.02, 2.22, respectively). Patients were more likely to develop a complication if they had ALIF + PLF, P/TLIF + PLF, ALIF, and P/TLIF than if they had PLF (odds ratios: 1.45, 1.23, 1.49, 1.12, respectively).

CONCLUSION

Variation in the surgical management of DS related to patient demographics, hospital charges, length of hospital stay, insurance type, comorbidities, and complication rates was found within the Nationwide Inpatient Sample database. During the acute phase of care immediately after surgery, PLF procedures were found to reduce length of hospital stay, hospital charges, and postoperative complications.

LEVEL OF EVIDENCE

3.

Stand-alone anterior lumbar interbody fusion for treatment of degenerative spondylolisthesis

We sought to evaluate the clinical and radiologic efficacy of stand-alone anterior lumbar interbody fusion (ALIF) for low grade degenerative spondylolisthesis, the favoured surgical management approach at our institution. The optimal approach for surgical management of spondylolisthesis remains contentious. We performed a prospective analysis of all consecutive patients with low grade lumbar spondylolisthesis who underwent ALIF between 2009 and 2013 by a single surgeon (n=27). The mean age was 64.9 years with a male to female ratio of 14:13. There were 32 levels operated and the average preoperative spondylolisthesis was 14.8%, which reduced to 6.4% postoperatively and 9.4% at the latest follow-up (p=0001). Postoperative disc height was increased to 175% of preoperative values and was statistically significant (p<0.001) and remained improved with an overall change of 139% at the latest follow-up. The radiological fusion rate was 91%. The 12-Item Short Form Health Survey (SF-12) mental and physical component summary improved from 31.7 to 43.0 (p=0.007) and from 35.4 to 51.7 (p=0.0026), respectively. The mean visual analogue scale pain score improved from 7.6 to 2.2 (p<0.001), and the mean Oswestry disability index improved from 56.9 to 17.8% (p<0.0001). The overall clinical success rate was 93%. The posterior disc height correlated with spondylolisthesis reduction (p=0.04) and the only clinical factor affecting reduction was body mass index (p=0.04). The present study provides encouraging short term results for stand-alone ALIF as a procedure for low grade lumbar degenerative spondylolisthesis. Future studies should include adequately powered, prospective, multicentre registry studies with long term follow-up to allow a better assessment of the relative benefits and risks.

Defining the inherent stability of degenerative spondylolisthesis: a systematic review

OBJECT A range of surgical options exists for the treatment of degenerative lumbar spondylolisthesis (DLS). The chosen technique inherently depends on the stability of the DLS. Despite a substantial body of literature dedicated to the outcome analysis of numerous DLS procedures, no consensus has been reached on defining or classifying the disorder with respect to stability or the role that instability should play in a treatment algorithm. The purpose of this study was to define grades of stability and to develop a guide for deciding on the optimal approach in surgically managing patients with DLS. METHODS The authors conducted a qualitative systematic review of clinical or biomechanical analyses evaluating the stability of and surgical outcomes for DLS for the period from 1990 to 2013. Research focused on nondegenerative forms of spondylolisthesis or spinal stenosis without associated DLS was excluded. The primary extracted results were clinical and radiographic parameters indicative of DLS instability. RESULTS The following preoperative parameters are predictors of stability in DLS: restabilization signs (disc height loss, osteophyte formation, vertebral endplate sclerosis, and ligament ossification), no disc angle change or less than 3 mm of translation on dynamic radiographs, and the absence of low-back pain. The validity and magnitude of each parameter's contribution can only be determined through appropriately powered prospective evaluation in the future. Identifying these parameters has allowed for the creation of a preliminary DLS instability classification (DSIC) scheme based on the preoperative assessment of DLS stability. CONCLUSIONS Spinal stability is an important factor to consider in the evaluation and treatment of patients with DLS. Qualitative assessment of the best available evidence revealed clinical and radiographic parameters for the creation of the DSIC, a decision aid to help surgeons develop a method of preoperative evaluation to better stratify DLS treatment options.

Health-related quality of life following decompression compared to decompression and fusion for degenerative lumbar spondylolisthesis: a Canadian multicentre study

BACKGROUND

Decompression alone (D) is a well-accepted treatment for patients with lumbar spinal stenosis (LSS) causing neurogenic claudication; however, D is controversial in patients with LSS who have degenerative spondylolisthesis (DLS). Our goal was to compare the outcome of anatomy-preserving D with decompression and fusion (DF) for patients with grade I DLS. We compared patients with DLS who had elective primary 1-2 level spinal D at 1 centre with a cohort who had 1-2 level spinal DF at 5 other centres.

METHODS

Patients followed for at least 2 years were included. Primary analysis included comparison of change in SF-36 physical component summary (PCS) scores and the proportion of patients achieving minimal clinically important difference (MCID) and substantial clinical benefit (SCB).

RESULTS

There was no significant difference in baseline SF-36 scores between the groups. The average change in PCS score was 10.4 versus 11.4 (p = 0.61) for the D and DF groups, respectively. Sixty-seven percent of the D group and 71% of the DF group attained MCID, while 64% of both D and DF groups attained SCB. There was no significant difference between D and DF for change in PCS score (p = 0.74) or likelihood of reaching MCID (p = 0.81) or SCB (p = 0.85) after adjusting for other variables.

CONCLUSION

In select patients with DLS, the outcome of D is comparable to DF at a minimum of 2 years.

Indications for anterior lumbar interbody fusion

Anterior lumbar interbody fusion (ALIF) has become a widely recognized surgical technique for degenerative pathology of the lumbar spine. Spinal fusion has evolved dramatically ever since the first successful internal fixation by Hadra in 1891 who used a posterior approach to wire adjacent cervical vertebrae in the treatment of fracture-dislocation. Advancements were made to reduce morbidity including bone grafting substitutes, metallic hardware instrumentation and improved surgical technique. The controversy regarding which surgical approach is best for treating various pathologies of the lumbar spine still exists. Despite being an established treatment modality, current indications of ALIF are yet to be clearly defined in the literature. This article discusses the current literature on indications on ALIF surgery.

Complications, reoperation rates, and health-care cost following surgical treatment of lumbar spondylolisthesis

BACKGROUND

Surgery remains the mainstay for management of lumbar spondylolisthesis and is considered an effective therapeutic modality following unsuccessful nonoperative treatment. Surgical procedures include decompression, decompression with instrumented arthrodesis, and decompression with noninstrumented arthrodesis. The purpose of this study was to examine the complications, reoperation rates, and health-care costs associated with each of these procedures.

METHODS

The MarketScan database was utilized to identify 16,556 patients with a primary diagnosis of lumbar spondylolisthesis who underwent surgical treatment from 2000 to 2009. Outcomes were evaluated in propensity score-matched cohorts, with complication rates analyzed with the chi-square test, reoperation rates analyzed using the Mantel-Haenszel test, and health-care resource use analyzed using the Wilcoxon signed-rank test.

RESULTS

Complication rates were significantly higher in patients who underwent arthrodesis compared with those who had decompression alone during the initial hospitalization (8.3% versus 4.8%; p < 0.0001) and at the time of the ninety-day follow-up (9.6% versus 5.5%; p < 0.0001). Complication rates were similar for those who received instrumented and noninstrumented arthrodesis. Patients who underwent decompression alone had higher reoperation rates at two years or more than those who received arthrodesis (15.7% versus 11.9%; p = 0.034). Patients with instrumented arthrodesis trended to have higher reoperation rates than those without instrumentation at five years or more (18.4% versus 10.6%; p = 0.063). Initial hospital costs and two-year and five-year overall costs (in 2009 U.S. dollars) were higher for patients managed with arthrodesis than for those who had decompression only ($102,906 versus $89,337; p = 0.0018). Also, patients who received instrumentation had higher hospitalization costs than those without instrumentation ($39,997 versus $27,309; p = 0.023) and higher overall costs at two years ($73,482 versus $60,394; p < 0.0001), although the difference was not significant at five years (p = 0.29).

CONCLUSIONS

Patients with lumbar spondylolisthesis who underwent decompressive laminectomy and spinal arthrodesis had lower reoperation rates but higher overall costs than patients treated with laminectomy alone. Noninstrumented arthrodesis was also associated with lower long-term reoperation rates and health-care costs compared with instrumented arthrodesis. The long-term outcomes and costs of these procedures should be evaluated in conjunction with clinical efficacy to ensure the most cost-effective treatment is utilized.

LEVEL OF EVIDENCE

Therapeutic level III. See Instructions for Authors for a complete description of levels of evidence.

Use of recombinant human bone morphogenetic protein-2 with local bone graft instead of iliac crest bone graft in posterolateral lumbar spine arthrodesis

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

Compare fusion rates between recombinant human bone morphogenetic protein-2 (rhBMP-2) and iliac crest bone graft (ICBG) with rhBMP-2 and local bone graft (LBG) (±bone graft extenders) in posterolateral fusion.

SUMMARY OF BACKGROUND DATA

Previous reports have shown higher fusion rates when adding rhBMP-2 to ICBG in lumbar posterolateral fusion, compared with ICBG alone. We compared the fusion success rates between rhBMP-2 delivered with ICBG versus that with LBG.

METHODS

Fusion rates were compared in patients with degenerative spondylolisthesis (1-2 levels) with accompanying lumbar stenosis. RhBMP-2 (INFUSE, Medtronic) was delivered on an absorbable collagen sponge (6 mg/side at 1.5 mg/mL) with ICBG alone or with LBG wrapped inside the sponge. Thin slice computed tomographic scans were assessed at 6, 12, and 24 months.

RESULTS

In a consecutive series, 16 patients (30 levels) received ICBG with rhBMP-2 and 35 patients (49 levels) received LBG with rhBMP-2. For the ICBG cohort, 80.0%, 93.4%, 96.7% of levels were fused at 6, 12, and 24 months. In contrast, for the local bone with rhBMP-2 cohort, 87.7%, 98.0%, and 98.0% were fused at 6, 12, and 24 months. There was no statistically significant difference in fusion success rates between the 2 groups at any time point. As for fusion quality, the fusion mass showed superior quality in ICBG group than in the local bone group at each time point.

CONCLUSION

This study validates the high fusion success rates previously reported by adding rhBMP-2 to ICBG and shows that local bone may be safely substituted for ICBG in 1- to 2-level posterolateral fusion. The fusion rates were comparable. The avoidance of ICBG harvest has implications for operative time, blood loss, and morbidity. Lastly, this is the first study that directly compares the fusion success rate and quality using local bone with rhBMP-2 versus ICBG with rhBMP-2 at various times.

LEVEL OF EVIDENCE

4.

SURGICAL MANAGEMENT OF DEGENERATIVE LUMBAR SPONDYLOLISTHESIS: A COMPARATIVE STUDY OF OUTCOMES FOLLOWING DECOMPRESSION WITH FUSION AND MICROENDOSCOPIC DECOMPRESSION

Fifty consecutive patients with degenerative lumbar spondylolisthesis were treated surgically. The first 17 patients (FU group) underwent decompression with fusion, the second 33 patients (MED group) underwent microendoscopic decompression (MED), and the outcomes following the two surgical methods were compared. The duration of follow-up ranged from 27 to 40 months in the FU group and from 25 to 40 months in the MED group. Clinical outcomes were evaluated with use of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire. Although statistically not significant, the degrees of improvement in all five functional scores were greater in the MED group than in the FU group. There was no influence of instability before MED to the clinical outcome, and a large percentage of slipping in the neutral position could lead to inadequate improvement in low back pain after MED, but MED is a useful, minimally invasive operation and can lead to a good clinical outcome for degenerative lumbar spondylolisthesis. Considering the lower invasiveness of MED, this procedure is recommended in case of degenerative lumbar spondylolisthesis with less than 20% slipping. Posterior decompression and fusion using pedicular screws is recommended in case of degenerative lumbar spondylolisthesis with over 20% slipping.

Cost-utility of lumbar decompression with or without fusion for patients with symptomatic degenerative lumbar spondylolisthesis

BACKGROUND CONTEXT

The most common surgical treatment of symptomatic degenerative lumbar spondylolisthesis (DLS) is decompression and instrumented fusion. However, contemporary, midline-sparing, microdecompressive techniques have shown good results for selected patients with stable Grade 1 DLS. Growing concerns over the rising cost and rates of spinal fusion warrant both clinical and economic comparative effectiveness research in this common spinal diagnosis.

PURPOSE

To determine the relative cost-utility of decompression with and without concomitant instrumented fusion for selected patients with DLS.

STUDY DESIGN/SETTING

Comparative cost-effectiveness study.

PATIENT SAMPLE

Probabilities and utilities were estimated from an observational cohort study and the current literature. Costing information was obtained from our institution (microcase costing data/patient) and the literature. Probabilities considered were perioperative and general mortality, probability of clinical improvement and clinical worsening, and reoperation.

OUTCOME MEASURES

The primary outcome was the incremental cost/utility ratio (ICUR) expressed as the differential cost per relative gain in quality-adjusted life-year (QALY).

METHODS

A Markov model with 10-year follow-up was developed. The analyses were carried out from the hospital's perspective. Sensitivity analysis was used to test the robustness of the model.

RESULTS

The cost-utility of decompression with fusion and decompression alone at 10 years postintervention was $3,281/QALY and $1,040/QALY, respectively. Compared with decompression alone, decompression plus instrumented fusion was associated with an improvement in quality of life at a cost of $185,878 per QALY in the base-case analysis. The ICUR was invariant to changes in clinical effectiveness of decompression alone, percentage of inpatient decompressions, and varying cost or QALY discounting rates. The ICUR was sensitive to change in QALY and cost structure changes.

CONCLUSIONS

For a select subgroup of patients with DLS (leg-dominant pain with a stable Grade 1 spondylolisthesis), decompression without fusion is significantly more cost effective than instrumented fusion and provides an opportunity for increased service delivery and/or cost savings for this growing population.

To fuse or not to fuse in lumbar degenerative spondylolisthesis: do baseline symptoms help provide the answer?

INTRODUCTION

Clinical symptoms in lumbar degenerative spondylolisthesis (LDS) vary from predominantly radiating pain to severe mechanical low back pain. We examined whether the outcome of surgery for LDS varied depending on the predominant baseline symptom and the treatment administered [decompression with fusion (D&F) or decompression alone (D)].

METHODS

213 consecutive patients (69 ± 9 years; 155f, 58 m) participated. Inclusion criteria were LDS, maximum three affected levels, no previous surgery at the affected level, and D (N = 56) or D&F (N = 157) as the operative procedure. Pre-op and at 12 months' follow-up (FU), patients completed the multidimensional Core Outcome Measures Index (COMI) including 0-10 leg-pain (LP) and LBP scales. At 12 months' FU, patients rated global outcome which was then dichotomised into "good" and "poor".

RESULTS

Pre-operatively, LBP and COMI scores were significantly worse (p < 0.05) in the D&F group than in the D group. The improvement in COMI at 12 months' FU was significantly greater for D&F than for D (p < 0.001) and was not influenced by the patient's declared "main problem" at baseline (back pain, leg pain, or neurological disturbances) (p > 0.05). There was a higher proportion (p = 0.01) of "good" outcomes at 12 months' FU in D&F (86%) than in D (70%). Multiple regression analysis, controlling for possible confounders, revealed treatment group to be the only significant predictor of outcome (adding fusion = better outcome).

DISCUSSION

Our study indicated that LDS patients showed better patient-based outcome with instrumented fusion and decompression than with decompression alone, regardless of baseline symptoms. This may be due to the fact that the underlying slippage as the cause of the stenosis is better addressed with fusion.

Single-level instrumented posterolateral fusion versus non-instrumented anterior interbody fusion for lumbar spondylolisthesis: a prospective study with a 2-year follow-up

BACKGROUND

Surgery for lumbar spondylolisthesis is widely performed. However, there have been no reports comparing posterolateral and anterior interbody fusion prospectively. We compared instrumented posterolateral fusion with anterior interbody fusion for L4 spondylolisthesis in a prospective study.

METHODS

Forty-six patients diagnosed with L4 degenerated spondylolisthesis were divided into two groups. Twenty-two consecutive patients underwent non-instrumented anterior interbody fusion using an iliac bone graft (ALIF; L4-L5 level), and 24 consecutive patients underwent instrumented posterolateral fusion with local bone (PLF; L4-L5 level). The rates of bone union, visual analog scale (VAS) score, Japanese Orthopedic Association (JOA) score, Oswestry Disability Index (ODI), surgical invasion, and complications were evaluated before and 2 years after surgery.

RESULTS

Age, VAS score, JOA score, and ODI were not significantly different between the two groups before surgery (P > 0.05). Success of bone union between the two groups was not significantly different (P > 0.05). Blood loss during surgery was significantly less; however, periods of bed rest and hospital stay were significantly longer in the ALIF group (P < 0.05). Overall patient satisfaction, and low back and leg pain in both groups were significantly improved after surgery; however, low back pain showed greater improvement in the ALIF group compared with the PLF group (P < 0.05). Complications such as donor site pain (4 patients in the ALIF group) and dural tearing (3 patients in the PLF group) were observed.

CONCLUSIONS

If single level fusion for L4 spondylolisthesis is performed, both anterior and posterior methods reduce patients' low back and leg pain. Improvement of low back pain was significantly greater after ALIF; however, periods of hospital stay and of bed rest were significantly longer.

A radiographic assessment of the ability of the extreme lateral interbody fusion procedure to indirectly decompress the neural elements

STUDY DESIGN

Prospective nonrandomized clinical study on the decompressive effect of the extreme lateral interbody fusion (XLIF) procedure.

OBJECTIVE

This study evaluates the results of interbody distraction from a lateral retroperitoneal approach for the treatment of lumbar degenerative conditions inclusive of central and/or lateral stenosis.

SUMMARY OF BACKGROUND DATA

Traditional treatment for symptomatic lumbar stenosis has been by direct posterior decompression (i.e., removal of ligamentum flavum, laminotomy/laminectomy, facetectomy, as needed). Stenotic symptoms may also be alleviated indirectly, through correction of intervertebral and foraminal height and correction of spinal alignment. Anterior-only spinal procedures rely on this indirect decompression when used in patients with radicular symptoms.

METHODS

Consecutive patients presenting with degenerative conditions that included concomitant lumbar stenosis were consented and treated via stand-alone XLIF. Pre- and postoperative radiographic measurements were made from plain lateral radiographs and sagittal and axial magnetic resonance imaging views by an independent radiologist using medical imaging software. Measurements included disc height, foraminal height, foraminal area, and canal diameter.

RESULTS

In all, 7 male and 14 female patients (mean age, 67.6 years; range, 40-83) underwent XLIF at 43 lumbar levels in an average operative time of 47 minutes and with an average 23 mL estimated blood loss per level. There were no intraoperative complications. Mean hospital stay was 29.5 hours. Transient postoperative psoas weakness occurred in 3 (14.3%) of the cases. Substantial dimensional improvement was evidenced in all radiographic parameters, with increases of 41.9% in average disc height, 13.5% in foraminal height, 24.7% in foraminal area, and 33.1% in central canal diameter. Two patients (9.5%) required a second procedure for additional posterior decompression and/or instrumentation.

CONCLUSION

The XLIF procedure provides the necessary decompression for the treatment of central and/orlateral stenosis in a minimally disruptive way, avoiding, in most cases, the need for the direct resection of posterior elements and associated morbidities. Indirect decompression may be limited in cases of congenital stenosis and/or locked facets. Its effect may also be reduced by postoperative subsidence and/or loss of correction.

Degenerative lumbar spondylolisthesis: evolution of surgical management

Watters III WC, Bono CM, Gilbert TJ, et al. An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spondylolisthesis. Spine J 2009;9:609-14 (this issue).

An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spondylolisthesis

BACKGROUND CONTEXT

The objective of the North American Spine Society (NASS) evidence-based clinical guideline on the diagnosis and treatment of degenerative lumbar spondylolisthesis is to provide evidence-based recommendations on key clinical questions concerning the diagnosis and treatment of degenerative lumbar spondylolisthesis. The guideline is intended to address these questions based on the highest quality clinical literature available on this subject as of January 2007. The goal of the guideline recommendations is to assist the practitioner in delivering optimum, efficacious treatment of and functional recovery from this common disorder.

PURPOSE

To provide an evidence-based, educational tool to assist spine care providers in improving the quality and efficiency of care delivered to patients with degenerative lumbar spondylolisthesis.

STUDY DESIGN

Systematic review and evidence-based clinical guideline.

METHODS

This report is from the Degenerative Lumbar Spondylolisthesis Work Group of the NASS Evidence-Based Clinical Guideline Development Committee. The work group was comprised of multidisciplinary spine care specialists, all of whom were trained in the principles of evidence-based analysis. Each member participated in the development of a series of clinical questions to be addressed by the group. The final questions agreed on by the group are the subject of this report. A literature search addressing each question and using a specific search protocol was performed on English language references found in MEDLINE, EMBASE (Drugs and Pharmacology) and four additional, evidence-based, databases. The relevant literature was then independently rated by at least three reviewers using the NASS-adopted standardized levels of evidence. An evidentiary table was created for each of the questions. Final grades of recommendation for the answer to each clinical question were arrived at via face-to-face meetings among members of the work group using standardized grades of recommendation. When Level I-IV evidence was insufficient to support a recommendation to answer a specific clinical question, expert consensus was arrived at by the work group through the modified nominal group technique and is clearly identified as such in the guideline.

RESULTS

Nineteen clinical questions were formulated, addressing issues of prognosis, diagnosis, and treatment of degenerative lumbar spondylolisthesis. The answers to these 19 clinical questions are summarized in this document. The respective recommendations were graded by the strength of the supporting literature that was stratified by levels of evidence.

CONCLUSIONS

A clinical guideline for degenerative lumbar spondylolisthesis has been created using the techniques of evidence-based medicine and using the best available evidence as a tool to aid practitioners involved with the care of this condition. The entire guideline document, including the evidentiary tables, suggestions for future research, and all references, is available electronically at the NASS Web site (www.spine.org) and will remain updated on a timely schedule.

The surgical management of degenerative lumbar spondylolisthesis: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To identify whether there is an advantage to instrumented or noninstrumented spinal fusion over decompression alone for patients with degenerative lumbar spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The operative management of degenerative spondylolisthesis includes spinal decompression with or without instrumented or noninstrumented spinal fusion. Evidence on the operative management of degenerative spondylolisthesis is still divisive.

METHODS

Relevant RCT and comparative observational studies between 1966 and June 2005 were identified. Abstracted outcomes included clinical outcome, reoperation rate, and solid fusion status. Analyses were separated into: 1) fusion versus decompression alone and 2) instrumented fusion versus noninstrumented fusion.

RESULTS

Thirteen studies were included. The studies were generally of low methodologic quality. A satisfactory clinical outcome was significantly more likely with fusion than with decompression alone (relative risk, 1.40; 95% confidence interval, 1.04-1.89; P < 0.05). The use of adjunctive instrumentation significantly increased the probability of attaining solid fusion (relative risk, 1.37; 95% confidence interval, 1.07-1.75; P < 0.05), but no significant improvement in clinical outcome was recorded (relative risk, 1.19; 95% confidence interval, 0.92-1.54). There was a nonsignificant trend toward lower repeat operations with fusion compared with both decompression alone and instrumented fusion.

CONCLUSION

Spinal fusion may lead to a better clinical outcome than decompression alone. No conclusion about the clinical benefit of instrumenting a spinal fusion could be made. However, there is moderate evidence that the use of instrumentation improves the chance of achieving solid fusion.

Use of Recombinant Human Bone Morphogenetic Protein-2 as an Adjunct in Posterolateral Lumbar Spine Fusion

INTRODUCTION

This study determines whether recombinant human bone morphogenetic protein-2 (rhBMP-2) (12 mg at the rate of 1.5 mg/mL) delivered on an absorbable collagen sponge with an added bulking agent can increase posterolateral lumbar spine fusion success rates and decrease time for fusion with autogenous bone grafts.

METHOD

A prospective, single institution, clinical case-matched, radiographic, cohort study was undertaken. A total of 52 patients underwent posterolateral lumbar arthrodesis with pedicle screw instrumentation. The experimental group (n=41) underwent placement of Iliac crest bone graft (ICBG) with InFUSE (12 mg/level at the rate of 1.5 mg/mL). The control group (n=11) consisted of sex-matched patients, consecutively collected over the same time period with an instrumented posterolateral arthrodesis and ICBG placed in the intertransverse space.

OUTCOME MEASURES

Thin-cut (2 mm) axial, coronal, and sagittal reconstructions were blindly evaluated for evidence of bridging bone and cortication of the fusion mass by 3 separate reviewers. Fusions were graded and an overall score was given to the quality of the fusion mass.

RESULTS

Fifty patients (ICBG alone n=11; ICBG/rhBMP-2 n=39) were available for CT evaluation at 2-year follow-up. An overall 97% (68/70 levels; Definite+Probably Fused) fusion rate in the rhBMP-2 group was achieved as compared to the 77% fusion rate (17/22 levels) in the ICBG alone group (P<0.05). In the rhBMP-2 group, 92% of the patients (36/39 patients) received an overall excellent subjective fusion rating as compared to 27% (3/11) in the control group (P<0.05). There was no computed tomographic evidence of soft-tissue ossification, dural ossification, or laminar bone regrowth in any patient.

CONCLUSIONS

The adjunctive use of rhBMP-2 and ICBG seems to be safe and results in significantly larger and more consistent posterolateral fusion masses.

Degenerative spondylolisthesis: review of current trends and controversies

STUDY DESIGN

A literature-based review.

OBJECTIVES

To review management and controversies and to present authors recommendations.

SUMMARY OF BACKGROUND DATA

There is considerable controversy regarding indication for surgery, role for decompression alone, and decompression with fusion with or without instrumentation.

METHODS

Review of English language medical literature.

RESULTS

The condition may stabilize itself with the collapse of the disc spaces and osteophytes but may continue to progress in nearly a third of the cases. It may cause predominantly back pain due to segmental instability, or radicular pain/neurogenic claudication secondary to root entrapment or spinal stenosis. When conservative treatment fails, the mainstay of surgical treatment is decompressive laminectomy and fusion, with or without instrumentation.

CONCLUSIONS

Decompression primarily relieves radicular symptoms and neurogenic claudication whereas fusion primarily relieves back pain by elimination of instability. The goals for instrumentation are to promote fusion and to correct deformity. Fusion has a better long-term outcome than decompression alone. There is evidence that instrumentation improves fusion rate but does not improve clinical outcome in a relatively short-term follow-up. However, outcome of pseudarthrosis cases deteriorates over time and solid fusion produces better long-term outcome. The benefit of instrumentation comes with a price of higher postoperative morbidity and complication rate. Bone morphogenetic proteins are being tried to increase the rate of fusion, without increasing the complication rate, but the cost is prohibitive. More recently, dynamic stabilization with instrumentation but without fusion has been introduced as an alternative treatment. The current trends of surgical treatment and controversies are discussed.

Predictors of outcomes after posterior decompression and fusion in degenerative spondylolisthesis

No consensus has been reached regarding surgical management of degenerative spondylolisthesis. The optimal type of surgical procedure and surgical indications have not been precisely defined. In order to screen for predictors of outcome, we retrospectively studied patient outcomes after posterior decompression and fusion for isolated lumbar degenerative spondylolisthesis. Twenty-four consecutive patients (age range 50-78 years) underwent primary surgery for isolated lumbar degenerative spondylolisthesis. The surgical procedure consisted of posterior decompression and pedicle screw instrumented fusion using autogeneous bone graft, with or without interbody fusion. Clinical and radiologic status were assessed using the Beaujon functional score and plain AP and lateral radiographs. A multivariate analysis was used to correlate the functional score increase with surgical procedure modifications and preoperative clinical and radiologic features in order to determine which of them led to better results. Eighteen patients completed the evaluation. Six others were lost to follow-up after a minimum of 0.87 years. Combining all the results, the mean follow-up was 2.87 years. The Beaujon score was improved in the 24 patients (P<0.001), and fusion was successful in all cases. Additional interbody fusion and preoperative leg pain were significantly correlated with larger score increase (P=0.016 and P=0.003). Posterior decompression and fusion is successful in treating lumbar degenerative spondylolisthesis. From this study, circumferential fusion improves the outcomes and leg pain is a fair indication for surgery.

Percutaneous ventral decompression for L4-L5 degenerative spondylolisthesis in medically compromised elderly patients: technical case report

OBJECTIVE AND IMPORTANCE:

To evaluate the efficacy of percutaneous ventral decompression for the treatment of elderly and medically compromised patients with degenerative lumbar spondylolisthesis (DLS).

CLINICAL PRESENTATION:

We present three cases of elderly and medically compromised patients with DLS. Each patient had one or more of the following disorders: diabetes, hypertension, or congestive heart failure. The mean age of the patients was 74.3 years (range, 66–84 yr). All three patients had compressive central canal stenosis on magnetic resonance imaging at the level of DLS. Their symptoms were bilateral buttock pain, leg pain, and back pain.

TECHNIQUE:

Percutaneous ventral decompression without violation of the posterior bony structure was performed under local anesthesia. After the surgery, the symptoms were relieved in all three patients. There was no further progression of spondylolisthesis or neurological complications during the follow-up period.

CONCLUSION:

Percutaneous ventral decompression is an alternative method of treating DLS in elderly and medically compromised patients, especially when general anesthesia is not recommended.

Acquired degenerative changes of the intervertebral segments at and suprajacent to the lumbosacral junction

A review of the imaging features of normal and degenerative anatomy of the spine on medical imaging studies shows features that have been largely overlooked or poorly understood by the imaging community in recent years. The imaging methods reviewed included computed tomography (CT) with multiplanar reconstructions and magnetic resonance imaging (MRI). A routine part of the MRI examination included fat-suppressed T2 weighted fast-spin- or turbo-spin-echo acquisitions. As compared to the normal features in asymptomatic volunteers, alterations in the observed CT/MRI morphology and MR signal characteristics were sought in symptomatic individuals. Findings in symptomatic subjects which departed from the normal anatomic features of the posterior spinal elements in asymptomatic volunteers included: rupture of the interspinous ligament(s), neoarthrosis of the interspinous space with perispinous cyst formation, posterior spinal facet (zygapophyseal joint) arthrosis, related central spinal canal, lateral recess (subarticular zone) and neural foramen stenosis, posterior element alterations associated with various forms of spondylolisthesis, and perispinal muscle rupture/degeneration. These findings indicate that the posterior elements are major locations of degenerative spinal and perispinal disease that may accompany or even precede degenerative disc disease. Although not as yet proven as a reliable source of patient signs and symptoms in all individuals, because these observations may be seen in patients with radicular, referred and/or local low back pain, they should be considered in the evaluation of the symptomatic patient presenting with a clinical lumbosacral syndrome. Imaging recommendations, in addition to the usual close scrutiny of these posterior spinal elements and perispinal soft tissues on CT and MRI, include the acquisition of high-resolution multiplanar CT reconstructions, and fat-suppressed T2 weighted fast-spin- or turbo-spin-echo sequence MRI in at least one plane in every examination of the lumbar spine.

The clinical usefulness of intraoperative spinal stiffness measurements

STUDY DESIGN

Determination of clinical results at least 2 years after lumbar spine surgery during which spinal stiffness measurements were made.

OBJECTIVES

To determine whether spine stiffness is predictive of clinical results after lumbar spine surgery for spinal stenosis, disc herniation, or degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The implied clinical wisdom is that instability of the spine portends a poor prognosis for relief of back pain after surgery in the absence of a fusion. The possibility that an objective measure of lumbar spinal motion segment unit stiffness could aid the surgeon in predicting satisfaction with treatment was considered.

METHODS

A total of 298 patients were measured intraoperatively with the spinal stiffness gauge to determine motion segment stiffness. Intraoperative spinal stiffness was analyzed to determine the influence of this measurement on clinical results.

RESULTS

Statistical analysis revealed that stiffness measurements did not correlate with clinical results of surgery. Patients with loose motion segment units before decompression did not demonstrate a significantly different level of satisfaction with surgical results a minimum of 2 years after surgery, whether they were fused or not fused. Based on stiffness measurements, a diagnosis of herniated nucleus pulposus or degenerative spondylolisthesis was indicative of a more unstable spine than a diagnosis of spinal stenosis.

CONCLUSIONS

Intraoperative spinal stiffness measurements did not predict clinical results after lumbar spine surgery.

Predicting complications in elderly patients undergoing lumbar decompression

A retrospective chart review of 68 patients 70 years of age or older who underwent decompressive procedures of the lumbar spine with or without fusion for benign conditions was performed to determine the ability of preoperative assessment of medical comorbidities to predict early postoperative complications. Patients 70 years of age or older who underwent decompressive procedures on the lumbar spine with or without fusion from January 1, 1990 to June 30, 1996 were identified. A chart review focused on preoperative comorbid diseases and early postoperative complications. A telephone survey was performed to assess patient satisfaction. Thirty-four women and 34 men with an average of 76.5 years averaged 1.6 comorbidities. Thirteen patients did not have comorbidities. The weighted comorbidity index resulted in an average score of 1.9. Eighty-five percent of the patients underwent posterolateral fusion. The total complication rate was 40%. Serious complications potentially affecting quality of life occurred in 12% of patients. The early mortality rate was 1.4%. The authors were unable to show a significant relationship between comorbidities and postoperative complications. Seventy-one percent of the 44 patients who were contacted at an average 42 months postoperatively were satisfied with their outcome. Elderly patients can safely undergo lumbar spinal procedures with an outcome similar to younger patients.

Quantitative changes in spinal canal dimensions using interbody distraction for spondylolisthesis

STUDY DESIGN

An experimental study was performed using cadaveric lumbar spines to evaluate the effect of anteriorly or laterally placed interbody distraction implants on the alteration of spinal canal and neuroforaminal dimensions.

OBJECTIVES

To quantify changes in the spinal canal and neuroforaminal dimensions using interbody fusion devices inserted at various configurations in cadaveric lumbar spines exhibiting degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Although several clinical studies have demonstrated successful treatment of degenerative spondylolisthesis with anterior interbody fusion, no study has shown the role of interbody distraction in improving lumbar spinal canal and foraminal stenosis.

METHODS

Five fresh cadaver lumbar spines exhibiting a degenerative spondylolisthesis or retrospondylolisthesis were used for the study. Computed tomography scans of each specimen and a silicon mold of the left intervertebral foramens were repeated in a consistent manner after pure compressive load (150 lb) was applied to simulate physiologic load (intact case), after two BAK (Sulzer SpineTech Inc., Minneapolis, MN) distraction plugs were anteriorly inserted into the intervertebral disc space (anterior distraction cases), and after one long BAK cage was laterally inserted from the left side (lateral distraction case). The cross-sectional area of the spinal canal was measured from computed tomography images using National Institutes of Health image software (Bethesda, MD). The spinal canal volume was calculated using the cross-sectional area and total scan thickness. Left intervertebral foraminal volumes were calculated from the weight of the silicon mold injected into the foramen. Descriptive statistics and a Student's t test were used to detect statistical differences in the spinal canal and neuroforaminal volumes before and after interbody distraction.

RESULTS

The cross-sectional canal area was significantly increased after anterior distraction (35.11%) and lateral distraction (33.14%). The spinal canal volume was markedly increased with anterior distraction (19.92%) and lateral distraction (21.96%). Left foraminal volume was also enhanced by 40.25% for anterior distraction and 41.03% for lateral distraction.

CONCLUSIONS

Interbody distraction either by anteriorly inserted plugs or laterally inserted threaded cagescan immediately improve the narrowed canal area and increase spinal canal, as well as foraminal volume for lumbar degenerative spondylolisthesis or retro- spondylolisthesis.

Acquired degenerative changes of the intervertebral segments at and suprajacent to the lumbosacral junction. A radioanatomic analysis of the nondiskal structures of the spinal column and perispinal soft tissues

In earlier evolutionary times, mammals were primarily quadrupeds. However, other bipeds have also been represented during the course of the Earth's several billion year history. In many cases, either the bipedal stance yielded a large tail and hypoplastic upper extremities (e.g., Tyrannosaurus rex and the kangaroo), or it culminated in hypoplasia of the tail and further development and specialization of the upper extremities (e.g., nonhuman primates and human beings). In the human species this relatively recently acquired posture resulted in a more or less pronounced lumbosacral kyphosis. In turn, certain compensatory anatomic features have since occurred. These include the normal characteristic posteriorly directed wedge-shape of the L5 vertebral body and the L5-S1 intervertebral disk; the L4 vertebral body and the L4-L5 disk may be similarly visibly affected. These compensatory mechanisms, however, have proved to be functionally inadequate over the long term of the human life span. Upright posture also leads to increased weight bearing in humans that progressively causes excess stresses at and suprajacent to the lumbosacral junction. These combined factors result in accelerated aging and degenerative changes and a predisposition to frank biomechanical failure of the subcomponents of the spinal column in these spinal segments. One other specific problem that occurs at the lumbosacral junction that predisposes toward premature degeneration is the singular relationship that exists between a normally mobile segment of spine (i.e., the lumbar spine) and a normally immobile one (i.e., the sacrum). It is well known that mobile spinal segments adjacent to congenitally or acquired fused segments have a predilection toward accelerated degenerative changes. The only segment of the spine in which this is invariably normally true is at the lumbosacral junction (i.e., the unfused lumbar spine adjoining the fused sacrum). Nevertheless, biomechanical failures of the human spine are not lethal traits; in most cases today, mankind reaches sexual maturity before spinal biomechanical failure precludes sexual reproduction. For this gene-preserving reason, degenerative spinal disorders will likely be a part of modern societies for the foreseeable eternity of the race. The detailed alterations accruing from the interrelated consequences of and phenomena contributing to acquired degenerative changes of the lumbosacral intervertebral segments as detailed in this discussion highlight the extraordinary problems that are associated with degenerative disease in this region of the spine. Further clinicoradiologic research in this area will progressively determine the clinical applications and clinical efficacy of the various traditional and newer methods of therapy in patients presenting with symptomatic acquired collapse of the intervertebral disks at and suprajacent to the lumbosacral junction and the interrelated degenerative alterations of the nondiskal structures of the spine.

Prospective study of surgical treatment of degenerative spondylolisthesis: comparison between decompression alone and decompression with graf system stabilization

STUDY DESIGN

A prospective study of patients with degenerative spondylolisthesis who underwent decompression of the spine, with and without stabilization using the Graf system.

OBJECTIVES

To assess the clinical result of decompression alone and decompression using the Graf system.

SUMMARY OF BACKGROUND DATA

The clinical outcome of lumbar stabilization for degenerative spondylolisthesis remains uncertain. There is no prospective study of differences in clinical outcome between patients who undergo decompression alone and those who undergo decompression and stabilization using the Graf system.

METHODS

Eighty-eight patients with degenerative spondylolisthesis were included in this study. All patients reported leg symptoms. Decompression alone (Group D) was performed in 42 patients during a 5-year period from 1988 through 1992. Decompression and stabilization with the Graf system (Group G) was performed in 46 patients during a 4-year period from 1993 through 1996. There was no statistical difference regarding sex, the age at operation, compensable cases, and preoperative duration between two groups. The two groups were evaluated at follow-up examinations 1 and 3 years after surgery. The clinical results were evaluated for all patients by means of a 4-grade scale, visual analog scale, recurrence of leg symptoms, and persistent low back pain. The radiographic and clinical findings were examined by an independent investigator.

RESULTS

The results according to the 4-grade scale deteriorated with time in both groups. There was no statistical difference between the two groups in the 4-grade scale, visual analog scale, or recurrence of leg symptoms at each follow-up time. Persistent low back pain in Group G was significantly lower than that in Group D at both the 1- and 3-year follow-ups.

CONCLUSIONS

Although lumbar Graf stabilization had no effect in preventing the recurrence of leg symptoms, there was a significant effect on reduction of low back pain at the 1- and 3-year follow-ups.

Clinical and pathologic characteristics of lumbar disk herniation in the elderly

The clinical and pathologic characteristics of lumbar disk herniation in 23 elderly patients (15 men and 8 women) who required surgical treatment were investigated. Average age at surgery was 67.3 years, and average follow-up was 23 months. Preoperatively, the predominant symptom was severe unilateral leg pain, and 13 patients were nonambulatory because of leg pain. Operative treatment included wide laminectomy in 8, hemilaminectomy in 3, fenestration in 10, and osteoplastic laminectomy in 2 patients. Four (17%) patients had disk herniation at the L2-L3 or L3-L4 level. Sequestered herniation with or without migration was observed in 15 (65%) patients. Of 14 sequestered disk fragments examined histologically, 8 (57%) specimens contained cartilaginous or bony end plate with anulus fibrosus or nucleus pulposus. Postoperatively, results were rated as excellent in 11 patients and good in 12; no patient was rated as fair or poor. Severe leg pain affecting activities of daily life is a predominant symptom of disk herniation in the elderly. For patients in whom conservative treatment has failed, operative treatment should be considered. In lumbar disk herniation in the elderly, the incidence of cephalad and lateral herniation is higher than in younger patients. In addition, sequestered and migrated herniations including end plate are frequent.

Patient outcomes after decompression and instrumented posterior spinal fusion for degenerative spondylolisthesis

STUDY DESIGN

A retrospective study of patient outcomes after decompression and fusion for degenerative spondylolisthesis, using the SF-36 survey and a functional questionnaire.

SUMMARY OF BACKGROUND DATA

In recent studies, patient outcomes have been examined more specifically; however, detailed functional outcomes are not available nor have widely used outcomes instruments been administered.

METHODS

Thirty patients aged more than 40 years (average, 60.1 years) who had degenerative spondylolisthesis were evaluated after decompression and instrumented posterior fusion. Charts and radiographs were also reviewed. Questionnaires were administered by telephone, and consisted of the Medical Outcomes Study short form (SF-36) and 27 questions designed to evaluate function, quality of life, medication usage, and satisfaction with surgical results.

RESULTS

Ninety-three percent of patient's were satisfied with their outcomes. Patients improved significantly in their ability to perform heavy and light activities, participate in social activities, sit, and sleep (P < 0.001) and also improved in pain, depression, and medication usage (P < 0.0001). SF-36 data showed significantly better overall assessment of health in all categories than that in a published cohort of patients with low back pain. The current study group also showed no difference in seven of eight categories when compared with the general population. Fusion rate was 93% at an average of 128 days. Three patients required reoperation: two for pseudarthrosis and one for a deep infection. A poorer outcome, scored by the SF-36, was associated with greater preoperative stenosis (P < 0.05) or occurrence of a complication (P < 0.05).

CONCLUSIONS

Patients treated with decompression and fusion for degenerative spondylolisthesis had improved functional outcomes, when measured by a disease-specific questionnaire and by widely used instruments.

Microdecompression and uninstrumented single-level fusion for spinal canal stenosis with degenerative spondylolisthesis

STUDY DESIGN

A retrospective review was completed on 21 patients who had a "least invasive" (one or two level) microdecompression and uninstrumented single-segment lumbar fusion for spinal canal stenosis with degenerative spondylolisthesis.

OBJECTIVE

To determine whether a "least invasive" approach to lumbar spinal canal stenosis and degenerative spondylolisthesis would yield acceptable results.

SUMMARY OF BACKGROUND DATA

The prevailing surgical technique for symptomatic spinal canal stenosis with degenerative spondylolisthesis is a wide midline decompression and instrumented fusion.

METHODS

On an average of 38 months postoperatively, 21 patients were personally assessed on four scores: 1) their overall satisfaction with the outcome of surgery, 2) an analog back and leg pain scale, 3) a functional evaluation scale, and 4) Ferguson (upshot) anterior-posterior lumbosacral and lateral flexion-extension radiographs.

RESULTS

The overall satisfactory outcome on all four scales was 16 (76%) of 21. Twenty of twenty-one patients had relief of their claudicant leg pain; the overall fusion rate was 18 (86%) of 21. Two of three patients with a pseudarthrosis had a successful outcome on the patient-oriented outcome (1, 2, and 3) scales (excluding the radiograph scale), and one was a failure. One patient with a solid fusion was a failure because of continuing back pain. One patient with a solid fusion was a failure because of continuing leg pain. The overall satisfactory outcome on the nonradiographic scales was 18 of 21, for an 86% patient satisfaction rate.

CONCLUSIONS

In this retrospective study, a "least invasive" surgical approach to lumbar degenerative spondylolisthesis with spinal canal stenosis causing claudicant leg pain produced acceptable results.

A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: Five-year follow-up by an independent observer

STUDY DESIGN

A prospective and consecutive study of surgical results obtained during serial follow-up investigations in patients who underwent surgery for central lumbar spinal stenosis.

OBJECTIVES

To evaluate the result after surgical decompression for lumbar spinal stenosis, at regular intervals after surgery, and to correlate these results with values for preoperative parameters; special interest was focused on the results in relation to the degree of constriction of the spinal canal.

SUMMARY OF BACKGROUND DATA

The outcome after surgery for spinal stenosis is debatable; long-term follow-up investigations have indicated deterioration with passing time. Results of studies in nonsurgical patients have demonstrated that the symptoms do not progress with time. Results of a meta-analysis of the literature on surgical results have demonstrated a wide variation of outcomes.

MATERIAL AND METHODS

In a prospective study, 105 consecutive patients who underwent surgical decompression (laminectomy with facet-preserving technique, but no fusion) were evaluated at follow-up examinations 4 months and 1, 2, and 5 years after surgery. At the follow-up examinations, the patient's opinion on the surgical result was registered, using a four-grade scale. The occurrence of pain at rest and at night was registered, as well as the patient's walking ability. Statistical analysis was performed, relating the surgical results to patient age, gender, preoperative duration of symptoms and radiographically observed constriction as described in Part I of this study. The radiologist was blinded to patient outcome. Logistic regression analysis was performed.

RESULTS

During the follow-up period, 19 patients underwent reoperation, consisting of fusion to treat lumbar pain (n = 4), repeat decompression because of progressive stenosis (n = 13), and repairs in response to surgical complications (n = 2). Follow-up results: The result, related to the recurrence of leg symptoms, deteriorated with passing time. Excellent results were reported by 63% to 67% at 4-month and 2-year follow-ups compared with 52% at the 5-year follow-up. There was a correlation between the constriction of the spinal canal and the outcome at all intervals. Patients with an anteroposterior diameter of 6 mm or less at the narrowest site had significantly better results. The logistic regression analysis demonstrated a significant correlation between a severe reduction of the anteroposterior diameter and excellent results and a tendency toward better results in patients with a shorter preoperative duration of symptoms. Improvement of walking ability was also associated with a pronounced constriction of the spinal canal.

CONCLUSION

The results after surgical decompression in patients with central spinal stenosis deteriorated with time. There was a significant correlation between good result and pronounced constriction of the spinal canal. Patients with a preoperative duration of symptoms of less than 4 years and patients with no preoperative back pain tended to have better surgical outcomes. The reoperation rate was 18% within 5 years. When surgery for spinal stenosis is contemplated, these prognostic factors should be taken into consideration: The "ideal patient" has a pronounced constriction of the spinal canal, insignificant lower back pain, no concomitant disease affecting walking ability, and a symptom duration of less than 4 years.

Seven- to 10-year outcome of decompressive surgery for degenerative lumbar spinal stenosis

STUDY DESIGN

Retrospective review and prospective follow-up of 88 patients who had decompressive laminectomy with or without fusion from 1983 to 1986.

OBJECTIVE

To determine the 7- to 10-year outcome of surgery for degenerative lumbar spinal stenosis.

SUMMARY OF BACKGROUND DATA

There is limited information on the impact of surgery for lumbar spinal stenosis on symptoms, walking ability, and satisfaction, as well as reoperation.

METHODS

Patients completed standardized questionnaires in 1993 that included items about reoperations, back pain, leg pain, walking capacity, and satisfaction with surgery. Associations between preoperative demographic and clinical variables and outcomes 7 to 10 years after surgery were evaluated in univariate and multivariate analyses.

RESULTS

Average preoperative age was 69 years and eight patients received fusion. Of 88 patients in the original cohort, 20 (23%) were deceased and 20 (23%) had undergone reoperation by 7- to 10-year follow-up. Fifty-five patients answered questionnaires. Average duration of follow-up was 8.1 years. Thirty-three percent of the respondents had severe back pain at follow-up, 53% were unable to walk two blocks, and 75% were satisfied with the results of surgery. The severity of current spine-related symptoms was a stronger correlate of physical functional status at the time of follow-up than age or nonspinal comorbid conditions.

CONCLUSIONS

Seven to 10 years after decompressive surgery for spinal stenosis, 23% of patients had undergone reoperation and 33% of respondents had severe back pain. Despite a high prevalence of nonspinal problems in this elderly cohort, spinal symptoms were the most important correlate of reduced functional status.

Outcome after laminectomy for lumbar spinal stenosis. Part I: Clinical correlations

All patients who underwent decompressive lumbar laminectomy in the Washtenaw County, Michigan metropolitan area during a 7-year period were studied for the purpose of defining long-term outcome, clinical correlations, and the need for subsequent fusion. Outcome was determined by questionnaire and physical examination from a cohort of 119 patients with an average follow-up evaluation interval of 4.6 years. Patients graded their outcome as much improved (37%), somewhat improved (29%), unchanged (17%), somewhat worse (5%), and much worse (12%) compared to their condition before surgery. Poor outcome correlated with the need for additional surgery, but there were few additional significant correlations. No patient had a lumbar fusion during the study interval. The outcome after laminectomy was found to be less favorable than previously reported, based on a patient questionnaire administered to an unbiased patient population. Further randomized, controlled trials are therefore necessary to determine the efficacy of lumbar fusion as an adjunct to decompressive lumbar laminectomy.