Lumbar posterolateral fusion alone or with transpedicular instrumentation in L4--L5 degenerative spondylolisthesis

Instrumented Versus Uninstrumented Posterolateral Fusion for Lumbar Spondylolisthesis: A Randomized Controlled Trial

BACKGROUND

In Scandinavia, spinal fusion is frequently performed without instrumentation, as use of instrumentation in the elderly can be complicated by poor bone quality and the risk of screw pull-out. However, uninstrumented fusion carries the risk of nonunion. We performed a randomized controlled trial in an attempt to determine if use of instrumentation leads to better outcomes and fusion rates when spinal fusion is performed for degenerative spondylolisthesis in the elderly.

METHODS

This was a randomized, single-center, open-label trial of patients with symptomatic single-level degenerative spondylolisthesis who were assigned 1:1 to decompression and fusion with or without instrumentation after at least 12 weeks of nonoperative treatment had failed. The primary outcome was the change in the Oswestry Disability Index (ODI), and secondary outcomes included fusion rates within 1 year, reoperation rates within 2 years, and changes in the EuroQol-5 Dimension-3 Level (EQ-5D) score.

RESULTS

Fifty-four subjects were randomized to each of the 2 groups, which had similar preoperative demographic and surgical characteristics. We found similar improvements in the ODI (p = 0.791), back pain, leg pain, and quality of life between groups at 1 and 2 years of follow-up. Solid fusion on computed tomography (CT) scans was noted in 94% of the patients in the instrumented group and 31% in the uninstrumented group (p < 0.001). One patient (2%) in the instrumented group and 7 (13%) in the uninstrumented group (p = 0.031) had a reoperation within 2 years after the index surgery.

CONCLUSIONS

We found no difference in patient-reported outcomes when we compared instrumented with uninstrumented fusion in patients with degenerative spondylolisthesis. The uninstrumented group had a significantly higher rate of nonunion and reoperations at 2 years.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Instrumented Versus Noninstrumented Spinal Fusion for Degenerative Lumbar Spondylolisthesis: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

This systematic review compares radiographic and clinical outcomes between instrumented and noninstrumented posterolateral lumbar spine fusions for the treatment of degenerative lumbar spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The optimal method of fusion for instability from degenerative lumbar spondylolisthesis remains to be an area of debate amongst spine surgeons. There are no prior comprehensive systematic review of comparative studies that compares outcomes between instrumented and noninstrumented posterolateral spine fusions for the treatment of degenerative lumbar spondylolisthesis.

MATERIALS AND METHODS

A systematic review was registered with PROSPERO and performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using the PubMed, SCOPUS, and Ovid MEDLINE databases. All level I-III comparative studies published in the English language investigating the clinical outcomes between instrumented and noninstrumented posterolateral spine fusions for the treatment of degenerative lumbar spondylolisthesis were included.

RESULTS

Seven studies (672 patients, 274 noninstrumented, 398 instrumented) were analyzed. One randomized study was level I evidence, 2 randomized studies were level II, and 4 nonrandomized studies were level III. Mean follow-up ranged from 1.4 to 5.9 years. Instrumented patients had a higher rate of solid fusion (87.6% vs. 77.1%, P=0.023) and a lower rate of definitive pseudarthrosis (5.3% vs. 19.9%, P<0.001). However, there was no difference in overall functional improvement at final follow-up between the 2 treatment groups (75.0% vs. 81.7%, P=0.258). In addition, there was no difference in reoperation or complication rates.

CONCLUSIONS

For the treatment of degenerative lumbar spondylolisthesis, there are significantly higher rates of fusion among patients undergoing instrumented posterolateral fusion compared with noninstrumented posterolateral fusion. However, there is no difference in overall functional improvement, pain-related outcome scores, reoperation rates, or complication rates between the 2 treatment groups.

LEVEL OF EVIDENCE

Level III-systematic review of level I-III studies.

Degenerative Spondylolisthesis: When to Fuse and When Not to? A New Scoring System

STUDY DESIGN

A prospective cohort.

OBJECTIVE

The objective of this study was to develop a scoring system for lumbar degenerative spondylolisthesis (LDS) that would guide decision-making.

BACKGROUND

The management protocol for LDS has been under debate, with no guidelines. Most studies oversimplify LDS as a homogenous entity.

MATERIALS AND METHODS

A retrospective analysis of 131 patients who underwent surgery for LDS between July 2007 and October 2011 with a minimum follow-up of 3 years was carried out on the basis of clinical, radiologic, and technical factors. A scoring system was conceptualized. Clinical: back pain score-2, age younger than 70 years-1, high-demand activity-1. Radiologic: segmental kyphosis-1.5, segmental dynamic translation-1, disk height >50% of adjacent level-1, facet effusion-1, sagittal facet-orientation-1. Technical: feasibility to decompress without causing instability-1.5. Its reliability was ascertained by a univariate analysis. The benchmark was set at 5.5 according to the Youden Index. This was followed by a prospective study for reliability analysis between November 2011 and January 2017 of 52 patients who underwent stand-alone decompression in LDS with a minimum follow-up of 24 months. Outcomes were evaluated using the Oswestry Disability Index and the Visual Analog Scale. Interobserver variability was determined. None of the patients in the retrospective or prospective group had undergone any lumbar surgery previously.

RESULTS

The mean Oswestry Disability Index and Visual Analog Scale of both the groups in the retrospective and the stand-alone decompression groups in prospective studies showed significant improvement. The interobserver reliability was high, with a κ value of 0.847.

CONCLUSIONS

The proposed scoring system helps view LDS as a heterogenous condition and assists in tailoring treatment for individual patients. For a select subgroup of patients with LDS, minimally invasive decompression (unilateral laminotomy and bilateral decompression using a minimally invasive surgery tubular retractor system) without fusion is adequate.

LEVEL OF EVIDENCE

Level III.

Computer-assisted surgical navigation is associated with an increased risk of neurological complications: a review of 67,264 posterolateral lumbar fusion cases

Background

Pedicle screw malposition may result in neurological complications following posterolateral lumbar fusions (PLF). While computer-assisted navigation (NAV) and intraoperative neuromonitoring (ION) have been shown to improve safety in deformity surgeries, their use in routine PLFs remain controversial. This study assesses the risk of complications and reoperation for pedicle screw revision following PLF with and without ION and/or NAV surgery.

Methods

Retrospective analyses were performed using the Truven Health MarketScan^® databases to identify patients that had primary PLF with and without NAV and/or ION for degenerative lumbar disorders from years 2007-2015. Patients undergoing concomitant interbody fusions, spinal deformity surgery or fusion to the thoracic spine were excluded. Complications and reoperation for pedicle screw revision within 90 days of surgery were assessed.

Results

During the study period, 67,264 patients underwent PLFs. NAV only was used in 3.5% of patients, ION only in 17.9% and both NAV and ION in 0.8% of patients. In univariate analyses, there was a difference in the risk of neurological injuries among groups (NAV only: 1.4%, ION only: 0.8%, NAV and ION: 0.5%, No NAV or ION: 0.6%, P<0.001). In multivariable models, the use of NAV was associated with a higher risk of neurological complications when compared to ION only or no ION or NAV [NAV vs. ION only: odds ratio (OR) and 95% confidence interval (CI) =2.1 (1.4, 3.2), P=0.002; NAV vs. no ION or NAV: OR and 95% CI =2.5 (1.7, 3.5), P<0.001]. There was no difference in reoperation rates among the groups (P=0.135).

Conclusions

Although the overall risk of neurological complications following PLFs is low, the use of NAV only was associated with an increased risk of neurological complications. No differences were observed in the rates of pedicle screw revision among groups.

Lumbar Spine Fusion Rates With Local Bone in Posterolateral and Combined Posterolateral and Interbody Approaches

Posterolateral lumbar fusion (PLF) used to treat degenerative lumbar conditions still faces pseudarthrosis. Bone graft choice is a key factor; a traditional choice has been autologous iliac crest bone graft (ICBG), but complication rates are quoted up to 39%. Local bone from laminectomy eliminates ICBG harvesting complications.

Methods

Two hundred forty-one patients underwent either PLF or PLF with interbody at a single lumbar level with a prospective, multicenter, randomized controlled trial only using local bone graft. Fusion was assessed with radiographs and CT.

Results

PLF fused bilaterally in 18% and unilaterally in 28.8% at 6 months and 35.7% and 50.3% at 12 months, respectively. At 6-month PLF + interbody, 1.1% fused bilaterally and 11.7% unilaterally; at 12 months, 5.4% fused all three areas, and 50.8% fused at least one area.

Discussion

Local bone fused substantially less than the "benchmark" ICBG.

Summary of Guidelines for the Treatment of Lumbar Spondylolisthesis

Degenerative lumbar spondylolisthesis is a common cause of low back pain, affecting about 11.5% of the United States population. Patients with symptomatic lumbar spondylolisthesis may first be treated with conservative management strategies including, but not limited to, non-narcotic and narcotic pain medications, epidural steroid injections, transforaminal injections, and physical therapy. For well-selected patients who fail conservative management strategies, surgical management is appropriate. This article summarizes the guidelines for the treatment of lumbar spondylolisthesis.

Decompression Versus Fusion for Grade I Degenerative Spondylolisthesis: A Meta-Analysis

STUDY DESIGN

Meta-analysis of evidence level I to IV studies.

OBJECTIVE

To compare decompression alone versus decompression plus fusion in the treatment of grade I degenerative spondylolisthesis (DS).

METHODS

Following established guidelines, we systematically reviewed 3 electronic databases to assess studies evaluating patients with grade I DS. We stratified all patients into 2 cohorts; the first cohort underwent a decompression-type surgery, and the second cohort underwent decompression plus fusion. We noted clinical outcomes, complications, reoperations, and surgical details such as blood loss. Descriptive statistics and random-effects models were used to determine the specified outcome metrics with 95% confidence intervals (CIs).

RESULTS

In both cohorts, the pain (legs and lower back) significantly decreased and the physical component of the Short Form 36 showed better patient clinical outcomes. The decompression cohort had a 5.8% complication rate (95% CI = 1.7-2.1), and the decompression plus fusion cohort had an 8.3% complication rate (95% CI = 5.5-11.6). The reoperation rate was higher in the decompression-only cohort (8.5%; 95% CI = 2.9-17.0) compared with the decompression plus fusion cohort (4.9%; 95% CI = 2.5-7.9).

CONCLUSIONS

There does not appear to be any advantage of one procedure over the other. Patients undergoing decompression alone tended to be older with a higher percentage of leg pain, whereas patients additionally undergoing fusion tended to be younger with more lower back pain. The decompression-only cohort had fewer complications but a higher revision rate.

Lateral lumbar interbody fusion in the elderly: a 10-year experience

OBJECTIVEElderly patients, often presenting with multiple medical comorbidities, are touted to be at an increased risk of peri- and postoperative complications following spine surgery. Various minimally invasive surgical techniques have been developed and employed to treat an array of spinal conditions while minimizing complications. Lateral lumbar interbody fusion (LLIF) is one such approach. The authors describe clinical outcomes in patients over the age of 70 years following stand-alone LLIF.METHODSA retrospective query of a prospectively maintained database was performed for patients over the age of 70 years who underwent stand-alone LLIF. Patients with posterior segmental fixation and/or fusion were excluded. The preoperative and postoperative values for the Oswestry Disability Index (ODI) were analyzed to compare outcomes after intervention. Femoral neck t-scores were acquired from bone density scans and correlated with the incidence of graft subsidence.RESULTSAmong the study cohort of 55 patients, the median age at the time of surgery was 74 years (range 70-87 years). Seventeen patients had at least 3 medical comorbidities at surgery. Twenty-three patients underwent a 1-level, 14 a 2-level, and 18 patients a 3-level or greater stand-alone lateral fusion. The median estimated blood loss was 25 ml (range 5-280 ml). No statistically significant relationship was detected between volume of blood loss and the number of operative levels. The median length of hospital stay was 2 days (range 1-4 days). No statistically significant relationship was observed between the length of hospital stay and age at the time of surgery. There was one intraoperative death secondary to cardiac arrest, with a mortality rate of 1.8%. One patient developed a transient femoral nerve injury. Five patients with symptomatic graft subsidence subsequently underwent posterior instrumentation. A lower femoral neck t-score < -1.0 correlated with a higher incidence of graft subsidence (p = 0.006). The mean ODI score 1 year postoperatively of 31.1 was significantly (p = 0.003) less than the mean preoperative ODI score of 46.2.CONCLUSIONSStand-alone LLIF can be safely and effectively performed in the elderly population. Careful evaluation of preoperative bone density parameters should be employed to minimize risk of subsidence and need for additional surgery. Despite an association with increased comorbidities, age alone should not be a deterrent when considering stand-alone LLIF in the elderly population.

Transcranial Motor Evoked Potential Alarm Criteria to Predict Foot Drop Injury During Lumbosacral Surgery

STUDY DESIGN

A retrospective cohort analysis.

OBJECTIVE

This study aims to investigate whether waveform alterations in transcranial motor evoked potentials (TCMEPs) can reliably predict postoperative foot drop.

SUMMARY OF BACKGROUND DATA

Nerve injury leading to foot drop is a potential complication of lumbosacral surgery. Very limited data exist on the use of intraoperative TCMEPs to identify iatrogenic foot drop.

METHODS

We retrospectively reviewed neuromonitoring data from 130 consecutive spine surgeries with instrumentation involving L4-S1. TCMEP waveform analysis included amplitude (A), area under the curve (AUC), latency (L), and duration (D). Patient outcomes were correlated with neuromonitoring results. Intraoperative alert criteria were established on the basis of observed intraoperative changes.

RESULTS

Three patients developed severe foot drop with a muscle weakness functional grade ranging from 0/5 to 3/5. Two patients developed a mild foot drop with functional grade 4/5. Twenty-three patients had preoperative weakness in an L5 distribution. One-hundred two patients who had neither preoperative nor postoperative neurological complications served as a control group. Amplitude significantly decreased in patients with a severe postoperative deficit (P = 0.005) as did AUC and duration (P < 0.05). Intraoperative alert criteria defined as a >65% decrease in AUC resulted in a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100%, 91.4%, 12%, and 100%, respectively. When defining an alert criteria as a >50% decrease in amplitude, sensitivity, specificity, PPV, and NPV were 100%, 87.9%, 8.8%, and 100%, respectively.

CONCLUSION

Reduction of TCMEP waveform associated with postoperative severe foot drop can be detected during lumbar surgery. Other waveform parameters such as AUC may predict foot drop better than the amplitude. Additional examinations in larger samples of foot drops are needed to validate these alert threshold findings.

LEVEL OF EVIDENCE

4.

Complication rates associated with open versus percutaneous pedicle screw instrumentation among patients undergoing minimally invasive interbody fusion for adult spinal deformity

OBJECTIVE

High-quality studies that compare outcomes of open and minimally invasively placed pedicle screws for adult spinal deformity are needed. Therefore, the authors compared differences in complications from a circumferential minimally invasive spine (MIS) surgery and those from a hybrid surgery.

METHODS

A retrospective review of a multicenter database of patients with spinal deformity who were treated with an MIS surgery was performed. Database inclusion criteria included an age of ≥ 18 years and at least 1 of the following: a coronal Cobb angle of > 20°, a sagittal vertical axis of > 5 cm, a pelvic incidence–lumbar lordosis angle of > 10°, and/or a pelvic tilt of > 20°. Patients were propensity matched according to the levels instrumented.

RESULTS

In this database, a complete data set was available for 165 patients, and after those who underwent 3-column osteotomy were excluded, 137 patients were available for analysis; 76 patients remained after propensity matching (MIS surgery group 38 patients, hybrid surgery group 38 patients). The authors found no difference in demographics, number of levels instrumented, or preoperative and postoperative radiographic results. At least 1 complication was suffered by 55.3% of patients in the hybrid surgery group and 44.7% of those in the MIS surgery group (p = 0.359). Patients in the MIS surgery group had significantly fewer neurological, operative, and minor complications than those in the hybrid surgery group. The reoperation rates in both groups were similar. The most common complication category for the MIS surgery group was radiographic and for the hybrid surgery group was neurological. Patients in both groups experienced postoperative improvement in their Oswestry Disability Index and visual analog scale (VAS) back and leg pain scores (all p < 0.05); however, MIS surgery provided a greater reduction in leg pain according to VAS scores.

CONCLUSIONS

Overall complication rates in the MIS and hybrid surgery groups were similar. MIS surgery resulted in significantly fewer neurological, operative, and minor complications. Reoperation rates in the 2 groups were similar, and despite complications, the patients reported significant improvement in their pain and function.

Osteogenic Potential of Tauroursodeoxycholic Acid as an Alternative to rhBMP-2 in a Mouse Spinal Fusion Model

The non-union rate after lumbar spinal fusion is potentially as high as 48%. To support efficient bone regeneration, recombinant human bone morphogenetic protein-2 (rhBMP-2) is commonly used as it is regarded as the most potent bone-inducing molecule. However, recently, there have been increasing concerns on the use of rhBMP-2 such as serious complications, including seroma and heterotopic ossification, and the low quality of bone at the center of fusion mass. Thus, many studies were conducted to find and to develop a potential alternative to rhBMP-2. In this study, we investigated the osteogenic potential of tauroursodeoxycholic acid (TUDCA) in the mouse fusion model and compared its effects with rhBMP-2. Twenty-four mice underwent bilateral posterolateral lumbar spinal fusion bone formation at L4-L5. Collagen sponge infused with saline, TUDCA, or rhBMP-2 was implanted at the fusion area. Two and 4 weeks postimplantation, bone formation and tissue regeneration were evaluated via micro-computed tomography and histological analysis. Compared with the TUDCA-treated group, the rhBMP-2 treatment produced a higher amount of bone fusion formation after 2 weeks but also showed higher resorption of the centralized bone after 4 weeks. Interestingly, the TUDCA-treated group developed higher trabecular thickness compared with rhBMP-2 after 4 weeks. Moreover, TUDCA treatment showed distinct angiogenic activity in human umbilical vein endothelial cells as confirmed by an in vitro tube formation assay. Our findings suggest that TUDCA is comparable to rhBMP-2 in supporting bone regeneration and spinal bone formation fusion by increasing trabecular thickness and promoting angiogenesis. Finally, our results indicate that TUDCA can be utilized as a potential alternative to rhBMP-2.

Kirschner Wire and Bone Cement is a Viable Alternative to Reconstruction of Large Iliac Bone Defects After Strut Bone Graft Harvesting

STUDY DESIGN

A retrospective study.

OBJECTIVE

To assess the safety and efficacy of iliac crest defect reconstruction using Kirschner wire (K-wire)/polymethylmethacrylate (PMMA) versus traditional autologous rib graft reconstruction.

SUMMARY OF BACKGROUND DATA

The iliac crest has been the preferred donor site for strut bone graft for various spinal fusion surgeries.

METHODS

Seventy-three patients (44 males and 29 females; average age: 57.2 y) were divided into 2 groups: the rib group (35 patients) and the K-wire/PMMA group (38 patients). All operations involved anterior spinal interbody fusion. Patients were followed-up, on average, for 34.2 months using plain radiographs and both pain and cosmesis visual analog scales (VAS) to assess the clinical results after surgery.

RESULTS

Almost all patients had pain VAS scores of ≤1 and grade 1 cosmesis VAS scores with no significant difference between the 2 groups in terms of either pain or cosmesis (P=1.00 and 0.505, respectively). In addition, few complications were noted in both groups. Radiographic complications in the rib group and the K-wire group numbered 4 (11%) and 2 (5%), respectively; however, did not significantly differ between the 2 groups (P=0.418). One case required intraoperative revision of the length of the K-wire and 1 case needed reoperation for iliac ring fracture and K-wire migration. An additional case required revision due to a bad fall.

CONCLUSIONS

K-wire and bone cement reconstruction is an effective and safe alternative method for large iliac bone defect repair when autologous rib graft is not available.

Utility of Intraoperative Neuromonitoring for Lumbar Pedicle Screw Placement Is Questionable: A Review of 9957 Cases

STUDY DESIGN

A retrospective database study.

OBJECTIVE

The goal of this study was to (1) evaluate the trends in the use of electromyography (EMG) for instrumented posterolateral lumbar fusions (PLFs) in the United States and (2) assess the risk of neurological injury following PLFs with and without EMG.

SUMMARY OF BACKGROUND DATA

Neurologic injuries from iatrogenic pedicle wall breaches during screw placement are known complications of PLFs. The routine use of intraoperative neuromonitoring (ION) such as EMG during PLF to improve the accuracy and safety of pedicle screw implantation remains controversial.

METHODS

A retrospective review was performed using the PearlDiver Database to identify patients who had PLF surgery with and without EMG for lumbar disorders from years 2007 to 2015. Patients undergoing concomitant interbody fusions or spinal deformity surgery were excluded. Demographic trends and risk of neurological injuries were assessed.

RESULTS

During the study period, 2007 to 2015, 9957 patients underwent PLFs. Overall, EMG was used in 2495 (25.1%) of these patients. There was a steady increase in the use of EMG from 14.9% in 2007 to 28.7% in 2009, followed by a steady decrease to 21.9% in 2015 (P < 0.0001). The risk of postoperative neurological injuries following PLFs was 1.35% (134/9957) with a risk of 1.36% (34/2495) with EMG and 1.34% (100/7462) without EMG (P = 0.932). EMG is used most commonly for PLFs in the Southern part of the United States.

CONCLUSION

In this retrospective national database review, we found that there was a steady increase in the routine use of EMG for PLFs followed by a steady decline. Regional differences were observed in the utility of EMG for PLFs. The risk of neurological complications following PLF in the absence of spinal deformity is low and the routine use of EMG for PLF may not decrease the risk.

LEVEL OF EVIDENCE

4.

Correlations of Japanese Orthopaedic Association Scoring Systems with Gait Parameters in Patients with Degenerative Spinal Diseases

OBJECTIVE

Japanese Orthopaedic Association (JOA) scoring systems were developed to evaluate the neurological function of patients with cervical or lumbar degeneration. As patient-based and multi-dimensional clinical evaluation tools, these systems should be capable of reflecting the walking disability of patients. The association between JOA scores and gait parameters, however, are not well characterized. The purpose of this study was to determine the correlations between JOA scores and gait parameters of patients with cervical spondylotic myelopathy (CSM) and lumbar intervertebral disc herniation (LDH).

METHODS

A total of 32 CSM and 30 LDH patients with gait dysfunction were recruited for the present study. All patients were diagnosed by two senior orthopaedic doctors and evaluated with JOA scoring systems. A body-mounted motion analyzer, the Intelligent Device for Energy Expenditure and Activity (IDEEA), was applied to measure gait parameters of patients across 30 m of flat floor in an orthopaedic ward. A linear regression model was used to determine the correlations between JOA scores and gait parameters. Multiple linear regressions were used to identify the relationships between subsections of the JOA systems and gait parameters.

RESULTS

Japanese Orthopaedic Association scores of LDH patients from the JOA lumbar scoring system are significantly correlated with gait speed (R ² = 0.557, P < 0.001) and stride length (R ² = 0.544, P < 0.001). JOA scores are also correlated with double support duration, step duration, cycle duration and cadence, and weakly correlated with single support duration. For the four subsections of the JOA lumbar scoring system, "restriction of activities of daily living" is the significant predictor of all gait parameters, especially gait speed (R ² = 0.573, P < 0.001) and stride length (R ² = 0.553, P < 0.001). However, JOA scores of CSM patients from the JOA cervical scoring system are only weakly correlated with these measures (all R ² < 0.3). For the four subsections of the JOA cervical scoring system, "motor function of the lower extremity" is a weak predictor of gait parameters (all R ² < 0.3).

CONCLUSIONS

There is a significant correlation between gait parameters and functional disability as measured by the JOA lumbar scoring system, which indicates that the JOA lumbar scoring system can reflect gait impairment. The JOA cervical scoring system, however, may need to be improved for efficiently evaluating the walking ability of CSM patients in the assessment of motor function of the lower extremity.

Is There a Role for Decompression Alone for Treating Symptomatic Degenerative Lumbar Spondylolisthesis?: A Systematic Review

BACKGROUND CONTEXT

A posterior decompression with an instrumented fusion is one of the most common surgical procedures performed for treating symptomatic spinal stenosis associated with degenerative spondylolisthesis (DS). However, some patients may benefit from a decompression alone, avoiding complications related to instrumentation and fusion.

OBJECTIVE

To identify the characteristics of patients with symptomatic DS who may be successfully treated with an isolated decompression.

STUDY DESIGN

A systematic literature review of studies including patients who underwent decompression without instrumentation for treatment of DS.

METHODS

A systematic review of the Medline database was performed. Retrospective and prospective studies of patients with DS who underwent a decompression were included, as well as studies comparing decompression with instrumented decompression. All the articles were classified according to their level of evidence.

RESULTS

Thirteen studies met all inclusion and exclusion criteria. We identified several characteristics that may be associated with a less favorable outcome after a decompression alone: a facet angle >50 degrees, a disk space of >6.5 mm, presence of low back pain rather than lower extremity symptoms, presence of hypermobility in the listhetic level on dynamic radiographs (>1.25 to 2 mm), and resection of the posterior elements. The majority of the studies comparing decompression alone to decompression and instrumented fusion included in our review suggested similar clinical outcomes with both procedures; however, with long-term follow-up, fusion may provide better outcomes. Decompression with a noninstrumented fusion is also a good alternative to improve symptoms in selected patients, potentially decreasing the risk of reoperation compared with an instrumented fusion.

CONCLUSIONS

Satisfactory clinical outcome can be achieved with an isolated decompression in selected patients, avoiding the additional risks and costs of instrumentation and spinal fusion. Noninstrumented fusion is also an interesting alternative to instrumented fusion for well-selected patients to decrease complications related to instrumentation.

Comparison of Allograft and Autograft in Lumbar Fusion for Lumbar Degenerative Diseases: A Systematic Review

Purpose/Aim of the study: The purpose of this analysis was to compare the clinical outcomes of vertebral fusion with allograft versus autograft bone.

MATERIALS AND METHODS

Medline, PubMed, Cochrane, EMBASE, and Google Scholar databases were searched until July 27, 2015 using the keywords: lumbar vertebrae, surgery, spondylolisthesis, bone transplantation, allograft, autograft. Inclusion criteria were randomized controlled trials (RCTs), two-arm prospective studies, retrospective studies, and cohort studies comparing the results of autograft and allograft in patients receiving lumbar spinal fusion. The outcomes were changes of Oswestry Disability Index (ODI) and visual analogue scale (VAS) pain scores from baseline at 1, 2, and 3 years after surgery and fusion rates.

RESULTS

Of 154 studies identified in the database searches, five were included in the quantitative analysis (one RCT, one prospective, and three retrospective studies). The mean patient age ranged from approximately 40 to 65 years, and approximately half of the patients were males. The total number of patients who received allografts was 333 and the total that received autografts was 175. The analysis revealed the change of ODI and VAS pain score at 1, 2 and 3 years was similar between the allograft and autograft groups (all, p > .05), as were the fusion rates (p > .05).

CONCLUSIONS

Both allograft and autograft provide acceptable outcomes for spinal fusion.

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.

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.

Good clinical outcomes and fusion rate of facet fusion with a percutaneous pedicle screw system for degenerative lumbar spondylolisthesis: minimally invasive evolution of posterolateral fusion

STUDY DESIGN

A retrospective clinical and radiographical study.

OBJECTIVE

To assess the clinical outcomes and fusion rate of facet fusion (FF) for degenerative lumbar spondylolisthesis (DLS).

SUMMARY OF BACKGROUND DATA

On the basis of the long-term clinical and radiological follow-up studies of posterolateral fusion (PLF)-that is, intertransverse process fusion with pedicle screw instrumentation-for DLS, we recognized that FF alone would be sufficient for spinal fusion.

METHODS

Eighty-eight patients who underwent FF for single-level DLS were retrospectively reviewed after at least 1 year of follow-up. The control group comprised 21 patients who underwent conventional PLF. The operative technique involved a 5-cm midline skin incision, bilateral laminar fenestration, and FF with autologous bone harvested from the spinous process. Percutaneous pedicle screws were then inserted through the fascia. The fusion rate of FF was evaluated using computed tomography, and the change in the range of motion at the fused level was assessed on flexion-extension lateral radiographs. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire was used to assess the therapeutic effectiveness of FF. The results of the Roland-Morris Disability Questionnaire and the visual analogue scales of low back pain, buttock and lower limb pain, and buttock and lower limb numbness were evaluated.

RESULTS

The fusion rate was 88.6% (78/88 cases). Among 10 patients with inadequate fusion, the average range of motion significantly decreased from 14.4° preoperatively to 4.3° postoperatively. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire category scores demonstrated therapeutic effectiveness in 93.0% of the patients for walking ability and in 73.0% of the patients for low back pain. The average preoperative scores of the Roland-Morris Disability Questionnaire and the visual analogue scales of low back pain, buttock and lower limb pain, and buttock and lower limb numbness were significantly reduced postoperatively in the FF group.

CONCLUSION

FF achieved good clinical outcomes that were superior to those of conventional PLF with a comparable fusion rate. It is useful for managing DLS and is a minimally invasive evolution of PLF.

LEVEL OF EVIDENCE

3.

Risk Factors For the Development of a Mobile Degenerative Spondylolisthesis at L4-L5

OBJECTIVE

The purpose of this study was to identify factors that may be important in determining whether a degenerative spondylolisthesis at L4-L5 is mobile.

SUMMARY OF BACKGROUND DATA

Degenerative scoliosis is a common condition among middle-aged and elderly adults. Sacropelvic morphology and orientation modulate the geometry of the lumbar spine and, consequently, the mechanical stresses at the lumbo-sacral junction. To date, no in vivo data exist to describe the relationship between these pelvic parameters and their association with a mobile spondylolisthesis.

METHOD

Sixty consecutive patients with a degenerative spondylolisthesis (DS) at L4-L5 with adequate imaging were identified. Patient groups were defined on the basis of whether the DS was mobile (Group A) or nonmobile (Group B) when comparing the upright plain lumbar radiograph to the supine magnetic resonance imaging (MRI). We assessed the grade of slip, lumbar lordosis, pelvic parameters, and facet characteristics (angles, tropism, presents of effusion, degenerative score-cartilage and sclerosis values) as well as disc degenerative score (Pfirrmann) at L4-L5.

RESULTS

There were 40 patients in Group A and 20 in Group B. No significant differences were found between groups for pelvic incidence (p = .409), pelvic tilt (p = .476), sacral slope (p = .785), lumbar lordosis (p = .695), degree of facet tropism (p = .38), and magnitude of the facet effusions (p = .01). Facet angle differences between groups approached significance (p = .058). Significant differences between groups were found in cartilage degenerative score (p = .01), facet sclerosis grade (p = .01), and disc degenerative score (p < .0001). In Group A, 10 of 40 (25%) reduced fully and were not apparent on the supine MRI.

CONCLUSIONS

Sagittal pelvic parameters do not play a significant role in differentiating between mobile and nonmobile DS at L4-L5. However, DS does appear to be associated with more sagittally orientated facets, higher Pfirrmann grade, and higher facet cartilage and sclerosis degenerative scores.

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.

Biomechanical stability of lateral interbody implants and supplemental fixation in a cadaveric degenerative spondylolisthesis model

STUDY DESIGN

In vitro cadaveric biomechanical study of lateral interbody cages and supplemental fixation in a degenerative spondylolisthesis (DS) model.

OBJECTIVE

To investigate changes in shear and flexion-extension stability of lateral interbody fusion constructs.

SUMMARY OF BACKGROUND DATA

Instability associated with DS may increase postoperative treatment complications. Several groups have investigated DS in cadaveric spines. Extreme lateral interbody fusion (XLIF) cages with supplemental fixation have not previously been examined using a DS model.

METHODS

Seven human cadaveric L4-L5 motion segments were evaluated using flexion-extension moments to ±7.5 N·m and anterior-posterior (A-P) shear loading of 150 N with a static axial compressive load of 300 N. Conditions were: (1) intact segment, (2) DS simulation with facet resection and lateral discectomy, (3) standalone XLIF cage, (4) XLIF cage with (1) lateral plate, (2) lateral plate and unilateral pedicle screws contralateral to the plate (PS), (3) unilateral PS, (4) bilateral PS, (5) spinous process plate, and (6) lateral plate and spinous process plate. Flexion-extension range of motion (ROM) data were compared between conditions and with results from a previous study without DS simulation. A-P shear displacements were compared between conditions.

RESULTS

Flexion-extension ROM after DS destabilization increased significantly by 181% of intact ROM. With the XLIF cage alone, ROM decreased to 77% of intact. All conditions were less stable than corresponding conditions with intact posterior elements except those including the spinous process plate. Under shear loading, A-P displacement with the XLIF cage alone increased by 2.2 times intact. Bilateral PS provided the largest reduction of A-P displacement, whereas the spinous process plate alone provided the least.

CONCLUSION

This is the first in vitro shear load testing of XLIF cages with supplemental fixation in a cadaveric DS model. The variability in sagittal plane construct stability, including significantly increased flexion-extension ROM found with most fixation conditions including bilateral PS may explain some clinical treatment complications in DS with residual instability.

LEVEL OF EVIDENCE

N/A.

The comparison of instrumented and non-instrumented fusion in the treatment of lumbar spondylolisthesis: a meta-analysis

PURPOSE

This meta-analysis compared whether fusion with or without instrumentation to treat this disease differed with respect to patient-centered outcomes.

METHODS

Medline, Cochrane, EMBASE, Google Scholar data bases were searched for randomized control trials that investigated patients with severe chronic lower back pain resulting from localized lumbar or lumbosacral instability caused by either isthmic spondylolisthesis or degenerative spondylolisthesis. Included randomized studies reported quantitative outcomes for low back pain and functional recovery. The primary outcome was the improvement of function and the secondary outcomes were the improvement of pain, patients' satisfactory level, and the fusion rate.

RESULTS

A significantly lower function change in patients with instrumented compared with non-instrumented from baseline (pooled standardized mean difference; -1.02 (95% CI -1.76 to -0.27); Z -2.67; (P = 0.008)]. There was no significant pain change for patients with instrumented compared with that of non-instrumented from baseline [pooled standardized mean difference; -0.07 (95% CI -1.25 to 1.12); Z -0.11; (P = 0.913)]. There was no significant difference in satisfactory level for patients with instrumented compared with that of non-instrumented [pooled OR; 2.36 (95% CI 0.91-6.11); Z 1.76; (P = 0.078)]. There was significantly higher fusion rate for patients with instrumented compared with that of non-instrumented [pooled OR; 3.28 (95% CI 2.22-4.85); Z 5.96; (P < 0.001)].

CONCLUSIONS

This meta-analysis found that inclusion of fusion surgery with instrumentation provided no benefit as evaluated by patient-reported outcomes in patients with lumbar spondylolisthesis.

LEVEL OF EVIDENCE

Not applicable.

Nerve injury after lateral lumbar interbody fusion: a review of 919 treated levels with identification of risk factors

BACKGROUND CONTEXT

Lateral lumbar interbody fusion (LLIF) has become an increasingly common minimally invasive procedure for selective degenerative deformity correction, reduction of low-grade spondylolisthesis, and indirect foraminal decompression. Concerns remain about the safety of the transpsoas approach to the spine due to proximity of the lumbosacral plexus.

PURPOSE

To address risk factors for iatrogenic nerve injury in a large cohort of patients undergoing LLIF.

STUDY DESIGN

Retrospective analysis of 919 LLIF procedures to identify risk factors for lumbosacral plexus injuries.

METHODS

The medical charts of patients who underwent transpsoas interbody fusion with or without supplemental posterior fusion for degenerative spinal conditions over a 6-year period were retrospectively reviewed. Patients with prior lumbar spine surgery or follow-up of less than 6 months were excluded. Factors that may affect the neurologic outcome were investigated in a subset of patients who underwent stand-alone LLIF.

RESULTS

Four hundred fifty-one patients (males/females: 179/272) met the inclusion criteria and were followed for a mean of 15 months (range, 6-53 months). Average age at the time of surgery was 63 years (range, 24-90 years). Average body mass index was 29 kg/m(2) (range, 17-65 kg/m(2)). A total of 919 levels were treated (mean, 2 levels per patient). Immediately after surgery, 38.5% of the patients reported anterior thigh/groin pain, whereas sensory and motor deficits were recorded in 38% and 23.9% of the patients, respectively. At the last follow-up, 4.8% of the patients reported anterior thigh/groin pain, whereas sensory and motor deficits were recorded in 24.1% and 17.3% of the patients, respectively. When patients with neural deficits present before surgery were excluded, persistent surgery-related sensory and motor deficits were identified in 9.3% and 3.2% of the patients, respectively. Among 87 patients with minimum follow-up of 18 months, persistent surgery-related sensory and motor deficits were recorded in 9.6% and 2.3% of the patients, respectively. Among patients with stand-alone LLIF, the level treated was identified as a risk factor for postoperative lumbosacral plexus injury. The use of recombinant human bone morphogenetic protein 2 was associated with persistent motor deficits.

CONCLUSIONS

Although LLIF is associated with an increased prevalence of anterior thigh/groin pain as well as motor and sensory deficits immediately after surgery, our results support that pain and neurologic deficits decrease over time. The level treated appears to be a risk factor for lumbosacral plexus injury.

Use of demineralized bone matrix in spinal fusion

Spinal fusion remains the gold-standard treatment for several pathological spine conditions. Although, autologous Iliac Crest Bone Grafting is considered the gold-standard graft choice to promote spinal fusion; however, it is associated with significant donor site morbidity and a limited graft quantity. Therefore, several bone graft alternatives have been developed, to augment arthrodesis. The purpose of this review is to present the results of clinical studies concerning the use of demineralized bone matrix (DBM), alone or as a composite graft, in the spinal fusion. A critical review of the English-language literature was conducted on Pubmed, using key word “demineralized bone matrix”, “DBM”, “spinal fusion”, and “scoliosis”. Results had been restricted to clinical studies. The majority of clinical trials demonstrate satisfactory fusion rates when DBM is employed as a graft extender or a graft enhancer. Limited number of prospective randomized controlled trials (4 studies), have been performed comparing DBM to autologous iliac crest bone graft in spine fusion. The majority of the clinical trials demonstrate comparable efficacy of DBM when it used as a graft extender in combination with autograft, but there is no clinical evidence to support its use as a standalone graft material. Additionally, high level of evidence studies are required, in order to optimize and clarify the indications of its use and the appropriate patient population that will benefit from DBM in spine arthrodesis.

Effects on inadvertent endplate fracture following lateral cage placement on range of motion and indirect spine decompression in lumbar spine fusion constructs: A cadaveric study

BACKGROUND

The lateral transpsoas approach to interbody fusion is gaining popularity. Existing literature suggests that perioperative vertebra-related complications include endplate breach owing to aggressive enedplate preparation and poor bone quality. The acute effects of cage subsidence on stabilization and indirect decompression at the affected level are unknown. The purpose of this study was to compare the kinematics and radiographic metrics of indirect decompression in lumbar spines instrumented with laterally placed cages in the presence of inadvertent endplate fracture, which was determined radiographically, to specimens instrumented with lateral cages with intact endplates.

METHODS

Five levels in 5 specimens sustained endplate fracture during lateral cage implantation followed by supplementary fixation (pedicle screw/rod [PSR]: n = 1; anterolateral plate [ALP]: n = 4), as part of a larger laboratory-based study. Range of motion (ROM) in these specimens was compared with 13 instrumented specimens with intact endplates. All specimens were scanned using computed tomography (CT) in the intact, noninstrumented condition and after 2-level cage placement with internal fixation under a 400-N follower load. Changes in disc height, foraminal area, and canal area were measured and compared between specimens with intact endplates and fractured endplates.

RESULTS

Subsidence in the single PSR specimen and 4 ALP specimens was 6.5 mm and 4.3 ± 2.7 mm (range: 2.2-8.3 mm), respectively. ROM was increased in the PSR and ALP specimens with endplate fracture when compared with instrumented specimens with intact endplates. In 3 ALP specimens with endplate fracture, ROM in some motion planes increased relative to the intact, noninstrumented spine. These increases in ROM were paralleled by increase in cage translations during cyclic loading (up to 3.3 mm) and an unpredictable radiographic outcome with increases or decreases in posterior disc height, foraminal area, and canal area when compared with instrumented specimens with intact endplates.

CONCLUSIONS

Endplate fracture and cage subsidence noted radiographically intraoperatively or in the early postoperative period may be indicative of biomechanical instability at the affected level concomitant with a lack of neurologic decompression, which may require revision surgery.

Grade 2 spondylolisthesis at L4-5 treated by XLIF: safety and midterm results in the "worst case scenario"

Spondylolisthesis is one of the most common indications for spinal surgery. However, no one approach has been proven to be more effective in treating spondylolisthesis. Recent advances in minimally invasive spine technology have allowed for different approaches to be applied to this indication, notably extreme lateral interbody fusion (XLIF). The risk, however, of using XLIF in treating grade II spondylolisthesis is the ventral position of the lumbar plexus, particularly at L4-5. Objective. This study reports the safety and midterm clinical and radiographic outcomes of patients with grade II lumbar spondylolisthesis treated with XLIF. Methods. 63 patients with grade II spondylolisthesis and spinal stenosis were treated with XLIF and were available for 12-month followup. Of those, 61 (97%) were treated at L4-5. Clinical (VAS, complications, and reoperation rate) and radiographic (anterolisthesis, disk height, and fusion) parameters were assessed. Study Design. Data were collected via a prospective registry and analyzed retrospectively. Results. Sixty-three patients were available for evaluations at least one year postoperatively. Average pain (visual analog scale) decreased from a score of 8.7 at baseline to 2.2 at 12 months postoperatively. Average anterior slippage was reduced by 73% and was well maintained. Average disk height (4.6 mm pre-op and 9.0 mm post-op) nearly doubled after surgery. Slight settling (average 1.3 mm) occurred over the twelve-month follow-up period. There were no neural injuries and no nonunions noted. Conclusions. XLIF is a safe and effective minimally invasive treatment alternative for grade II spondylolisthesis. Real-time neurological monitoring and attention to technique are mandatory.

An outcome measure of functionality and pain in patients with lumbar disc herniation: a validation study of the Japanese Orthopedic Association (JOA) score

BACKGROUND

Lumbar disc hernia (LDH) is a common cause of low back pain and radicular leg pain. The Japanese Orthopedic Association (JOA) score is a very short instrument for measuring functionality and pain in these patients. This study aimed to translate and validate the JOA score for use in Iran.

METHODS

This was a prospective clinical validation study. Translation of the English version of the questionnaire was performed in accordance with published guidelines. A sample of patients with LDH was asked to respond to the questionnaire at two points in time--at preoperative and postoperative (6 months follow-up) assessments. To test reliability, the internal consistency was assessed by use of Cronbach's alpha coefficient. Validity was evaluated by use of known-groups comparison.

RESULTS

A total of 117 patients with LDH were entered into the study. The mean age of patients was 45 (SD = 11) and Cronbach's alpha coefficients for the JOA score at the preoperative and postoperative assessments were 0.67 and 0.81, respectively. Validity as performed by known-groups analysis also showed the result was satisfactory. The instrument discriminated well between sub-groups of patients who differed in age and in a standard predictive measure of lumbar disc surgery (the Finneson-Cooper score).

CONCLUSIONS

In general, the Iranian version of the JOA score performed well and the findings suggest that it is a reliable and valid measure of functionality and pain among LDH patients.

Grafton and local bone have comparable outcomes to iliac crest bone in instrumented single-level lumbar fusions

STUDY DESIGN

Prospective multicenter randomized clinical trail.

OBJECTIVE

The goal of our 2-year prospective study was to perform a randomized clinical trial comparing the outcomes of Grafton demineralized bone matrix (DBM) Matrix with local bone with that of iliac crest bone graft (ICBG) in a single-level instrumented posterior lumbar fusion.

SUMMARY OF BACKGROUND DATA

There has been extensive research and development in identifying a suitable substitute to replace autologous ICBG that is associated with known morbidities. DBMs are a class of commercially available grafting agents that are prepared from allograft bone. Many such products have been commercially available for clinical use; however, their efficacy for spine fusion has been mostly based on anecdotal evidence rather than randomized controlled clinical trials.

METHODS

Forty-six patients were randomly assigned (2:1) to receive Grafton DBM Matrix with local bone (30 patients) or autologous ICBG (16 patients). The mean age was 64 (females [F] = 21, males [M] = 9) in the DBM group and 65 (F = 9, M = 5) in the ICBG group. An independent radiologist evaluated plain radiographs and computed tomographic scans at 6-month, 1-year, and 2-year time points. Clinical outcomes were measured using Oswestry Disability Index (ODI) and Medical Outcomes Study 36-Item Short Form Health Survey.

RESULTS

Forty-one patients (DBM = 28 and ICBG = 13) completed the 2-year follow-up. Final fusion rates were 86% (Grafton Matrix) versus 92% (ICBG) (P = 1.0 not significant). The Grafton group showed slightly better improvement in ODI score than the ICBG group at the final 2-year follow-up (Grafton [16.2] and ICBG [22.7]); however, the difference was not statistically significant (P = 0.2346 at 24 mo). Grafton showed consistently higher physical function scores at 24 months; however, differences were not statistically significant (P = 0.0823). Similar improvements in the physical component summary scores were seen in both the Grafton and ICBG groups. There was a statistically significant greater mean intraoperative blood loss in the ICBG group than in the Grafton group (P < 0.0031).

CONCLUSION

At 2-year follow-up, subjects who were randomized to Grafton Matrix and local bone achieved an 86% overall fusion rate and improvements in clinical outcomes that were comparable with those in the ICBG group.

Surgical outcomes of degenerative spondylolisthesis with L5-S1 disc degeneration: comparison between lumbar floating fusion and lumbosacral fusion at a minimum 5-year follow-up

STUDY DESIGN

A retrospective clinical and radiographic study was performed.

OBJECTIVE

The purpose of this study was to compare outcomes of patients with degenerative spondylolisthesis and a preexisting degenerative L5-S1 disc treated with a lumbar floating fusion (LFF) versus lumbosacral fusion (LSF).

SUMMARY OF BACKGROUND DATA

Fusion for treatment of degenerative spondylolisthesis often ends at the L5 level. These patients usually had a preexisting L5-S1 disc degeneration; however, no literature mentions the role of prophylactic LSF in degenerative spondylolisthesis associated with L5-S1 disc degeneration.

METHODS

A total of 107 patients with a minimum 5-year follow-up who had lumbosacral or LFF with pedicle instrumentation for degenerative spondylolisthesis were included. UCLA (University of California, Los Angeles) classification was used to evaluate the radiographic results of the L5-S1 segment. The Oswestry Disability Index (ODI) and modified Brodsky's criteria were used to evaluate patients' clinical results. The incidence of adjacent segment disease (ASD) (includes radiographic and clinical ASD) of both ends was recorded.

RESULTS

There were no statistically significant differences in sex, age distribution, or amount of follow-up between the LFF and LSF groups. The LSF group had a higher percentage of patients that underwent total L5 laminectomy with loss of L5-S1 posterior ligament integrity (LSF = 92% vs. LFF = 67%, P = 0.019). The higher incidence of cephalic ASD in the LSF group was statistically significant (LSF = 25% vs. LFF = 9.7%, P = 0.049). Although no patient in the LSF group developed L5-S1 ASD, need for L5-S1 segment revision surgery was not prevented with LSF. Clinical outcomes on the basis of the success rate (LFF = 85.5% vs.LSF = 70.8%, P = 0.103) and ODI difference (LFF = 28.97 ± 15.82 vs. LSF = 23.04 ± 10.97, P = 0.109), there were no statistically significant difference between these two groups.

CONCLUSION

Posterior instrumentation with posterolateral LFF for the treatment of degenerative spondylolisthesis with concomitant L5-S1 disc degeneration results in a high percentage of satisfactory clinical results. Extended fusion to the sacrum did not provide a better clinical result. LSF could not reduce the incidence of revision surgery at the L5-S1 segment and involved greater incidence of cephalic ASD.

Intraoperative and early postoperative complications in extreme lateral interbody fusion: an analysis of 600 cases

STUDY DESIGN

Prospective analysis of 600 extreme lateral interbody fusion (XLIF) approach procedures for intraoperative and perioperative complications.

OBJECTIVE

To delineate and describe complications in a large, prospective series of minimally invasive lateral lumbar fusion procedures (XLIF).

SUMMARY OF BACKGROUND DATA

While some small series of lateral lumbar fusion have discussed complications, no results from large studies have been reported.

METHODS

A total of 600 patients were treated with a lateral approach to fusion (XLIF) for degenerative spinal conditions. Data were collected prospectively on all patients and analyzed for demographic, diagnostic, and hospitalization information to identify operative and early postoperative complications. Documented complication types and rates in this large series were compared with smaller prior reports on lateral approach fusions, as well as other minimally invasive (mini-anterior lumbar interbody fusion and minimally invasive surgical [MIS] transforaminal lumbar interbody fusion) and more traditional fusion approaches (posterior intertransverse fusion, anterior lumbar interbody fusion, posterior lumbar interbody fusion, transforaminal lumbar interbody fusion).

RESULTS

Seven hundred forty-one levels were treated, 80.8% single level, 15.0% 2 level, 4.0% 3 level, 0.2% 4 level; 59.3%, including the L4 to L5 levels. A total of 99.2% included supplemental internal fixation; 83.2% included pedicle screw fixation (predominantly unilateral). Hemoglobin change from pre- to postoperation averaged 1.38. Hospital stay averaged 1.21 days. The overall incidence of perioperative complications (intraoperation and out to 6 weeks postoperation) was 6.2%: 9 (1.5%) in-hospital surgery-related events, 17 (2.8%) in-hospital medical events, 6 (1.0%) out-of-hospital surgery-related events, and 5 (0.8%) out-of-hospital medical events. There were no wound infections, no vascular injuries, no intraoperative visceral injuries, and 4 (0.7%) transient postoperative neurologic deficits. Eleven events (1.8%) resulted in additional procedures/reoperation.

CONCLUSIONS

Compared with traditional open approaches, the MIS lateral approach to fusion by using the XLIF technique resulted in a lower incidence of infection, visceral and neurologic injury, and transfusion as well as markedly shorter hospitalization. Complications in MIS XLIF compare favorably with those from other MIS fusion procedures; duration of hospitalization is shorter than with any previously reported technique.

Dynamically evoked, discrete-threshold electromyography in the extreme lateral interbody fusion approach

OBJECT

because the psoas muscle, which contains nerves of the lumbar plexus, is traversed during the extreme lateral interbody fusion (XLIF) approach, appropriate nerve monitoring is needed to avoid nerve injury during surgery and prevent approach-related neural deficit. This study was performed to assess the effectiveness of dynamically evoked electromyography (EMG) to detect and prevent neural injury during the XLIF approach.

METHODS

one hundred two patients undergoing XLIF at L3-4 and/or L4-5 were enrolled in a prospective, multicenter, nonrandomized clinical study. The EMG threshold values for each of the 3 successive dilators were recorded at the surface of the psoas muscle, mid-psoas, and on the spine. At each location, the dilators were rotated 360°, taking recordings immediately posterior, superior, anterior, and inferior. For each dilator, the authors noted the rotational position (the angle in degrees) at which the lowest threshold was found. Findings of pre- and postoperative neurological examinations were also recorded.

RESULTS

nerves were identified within proximity of the dilators (alert-level EMG feedback) in 55.7% of all cases during the XLIF approach. Although nerves were more commonly identified in the posterior margin (63%), there was significant variability in the location of nerves identified. Despite the fact that the posterior half of the disc space was targeted in 90% of cases, no significant long-lasting neural deficits were identified in any case; 27.5% experienced new iliopsoas/hip flexion weakness and 17.6% experienced new postoperative upper medial thigh sensory loss. Transient motor deficits were identified in 3 patients (2.9%), and all had resolved by the 6-month follow-up visit.

CONCLUSIONS

the ability to identify and report a discrete, real-time EMG threshold during the transpsoas approach helps to avoid nerve injury and is required for the safe performance of the XLIF procedure. Additionally, nerve location is variable, thus reinforcing the need for real-time directional and proximity information.

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 safety and efficacy of OP-1 (rhBMP-7) as a replacement for iliac crest autograft for posterolateral lumbar arthrodesis: minimum 4-year follow-up of a pilot study

BACKGROUND CONTEXT

Although autogenous bone is still considered to be the gold standard graft material for promoting spinal fusion, other bone graft substitutes have been developed in an attempt to improve arthrodesis rates and avoid the complications associated with the procurement of autograft. The bone morphogenetic proteins (BMPs) represent a family of osteoinductive growth factors that are known to stimulate the osteoblastic differentiation of stem cells. Osteogenic protein-1 (OP-1) Putty is a commercially available BMP preparation that is already approved for use in humans. Previous clinical studies involving patients with degenerative spondylolisthesis have reported that the efficacy and safety of OP-1 Putty is comparable to that of autograft at both 1- and 2-year follow-up.

PURPOSE

The purpose of this study was to evaluate the intermediate-term efficacy and safety of OP-1 Putty as an alternative to autogenous bone by comparing the 4-year radiographic, clinical, and safety data of these same patients who underwent decompression and uninstrumented fusion with either OP-1 Putty or iliac crest autograft.

STUDY DESIGN/SETTING

A prospective, randomized, controlled, multicenter clinical pilot study.

PATIENT SAMPLE

Thirty-six patients undergoing decompressive laminectomy and single-level uninstrumented fusion for degenerative spondylolisthesis and symptomatic spinal stenosis were randomized in a 2:1 fashion to receive either OP-1 Putty (24 patients) or autogenous iliac crest bone graft (12 patients).

OUTCOME MEASURES

Patient-reported outcome measures consisting of Oswestry Disability Index and Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) scores were used to evaluate clinical efficacy. Perioperative data including operative time, estimated blood loss, and duration of hospital stay were also recorded for each surgery. Postoperatively, a neurological examination and an assessment of donor-site pain (if applicable) were performed at every follow-up visit. Radiographic fusion success was defined as the presence of continuous bridging bone formation between the transverse processes at the level of the spondylolisthesis with minimal motion evident on dynamic lateral x-ray films. The primary efficacy endpoint was the overall success rate, a composite measure derived from both radiographic and clinical parameters. The safety of OP-1 Putty was confirmed by comparing the nature and frequency of all adverse events and complications that were prospectively observed in either of the groups.

METHODS

Thirty-six patients with degenerative spondylolisthesis and symptoms of neurogenic claudication underwent decompressive laminectomy and single-level uninstrumented fusion with either OP-1 Putty or autograft. All patients were evaluated at 6 weeks and 3, 6, 9, 12, and 24 months, after which time they were instructed to return on a yearly basis. Multiple neuroradiologists blinded to the assigned treatment reviewed static and dynamic X-ray films with digital calipers to assess fusion status according to the presence of continuous bridging bone across the transverse processes as well as the amount of residual motion evident at the level of interest. Oswestry Disability Index surveys and SF-36 questionnaires were used to assess clinical outcomes.

RESULTS

At the 48-month time point, complete radiographic and clinical data were available for 22 of 36 patients (16 OP-1 Putty and 6 autograft) and 25 of 36 patients (18 OP-1 Putty and 7 autograft), respectively. Radiographic evidence of a solid arthrodesis was present in 11 of 16 OP-1 Putty patients (68.8%) and 3 of 6 autograft patients (50%). Clinically successful outcomes defined as at least a 20% improvement in preoperative Oswestry scores were experienced by 14 of 19 OP-1 Putty patients (73.7%) and 4 of 7 autograft patients (57.1%); these clinical findings were corroborated by similar increases in SF-36 scores. The respective overall success rates of the OP-1 Putty and autograft group were 62.5% and 33.3%. In this study, there were no incidents of local or systemic toxicity, ectopic bone production, or other adverse events directly related to the use of OP-1 Putty.

CONCLUSION

Despite the challenges associated with obtaining a solid uninstrumented fusion in patients with degenerative spondylolisthesis, the rates of radiographic fusion, clinical improvement, and overall success associated with the use of OP-1 Putty were at least comparable to that of the autograft controls for at least 48 months after surgery. These results appear to validate the short-term results previously reported for OP-1 Putty and suggest that this material may potentially represent a viable bone graft substitute for certain fusion applications.

Long-term outcomes of two different decompressive techniques for lumbar spinal stenosis

STUDY DESIGN

A prospective study to evaluate the outcomes of 2 different decompressive techniques for lumbar spinal stenosis.

OBJECTIVE

To explore a more effective and less invasive decompression technique without instrument and fusion for lumbar spinal stenosis.

SUMMARY OF BACKGROUND DATA

The traditional surgical decompression of spinal stenosis involves laminectomy or unilateral laminotomy. Even in unilateral laminotomy cases, 85.3% had an excellent-to-fair operative result, and the incidence of complications was 9.8%. Although the addition of instrumentation does not increase the complication rate, but compared to the efficiency, the higher costs was controversial. Minimal invasion and destabilization are recommended.

METHODS

This prospective study included 152 consecutive patients, sequentially divided into 2 groups, underwent Windows technique (group A) and decompressive laminectomy (group B) by 2 groups of surgeons.

RESULTS

The evaluation of the back pain, leg pain, walking tolerance, and neurologic recovery were performed before surgery and after surgery. In group A, at the final evaluation, the overall results were good to excellent in 89% (68/76) of the patients, fair 11% (8/76), and poor 0%. In group B, at the final evaluation, the overall results were good to excellent in 63% (48/76) of the patients, fair 30% (23/76), and poor 7% (5/76).

CONCLUSION

Degenerative spinal stenosis can be decompressed adequately with preserving the posterior elements. The "Windows technique" laminoforaminotomy, which obtained satisfactory long-term outcomes with few complications and low cost, can be a standard procedure for the surgical treatment of the degenerative spinal stenosis even with slight congenital spinal stenosis.

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.

A prospective randomized study of unilateral versus bilateral instrumented posterolateral lumbar fusion in degenerative spondylolisthesis

STUDY DESIGN

Prospective randomized study on 82 patients with degenerative lumbar spondylolisthesis, having undergone posterolateral fusion with bilateral or unilateral instrumentation.

OBJECTIVE

To determine the effectiveness of unilateral pedicle instrumentation in clinical outcome and rate of union in comparison with the classic bilateral system.

SUMMARY OF BACKGROUND DATA

Instrumentation has proved to have advantages and disadvantages related to its rigidity. The use of less rigid systems applied to posterior lumbar fusions proved promising according to the results achieved in both experimental and clinical field.

METHODS

Eighty-two patients were randomized into 2 groups: Group 1 (n = 42) had had bilateral instrumentation, and Group 2 (n = 40) had only had unilateral instrumentation. One case from Group 1, L3-S1 dropped out; only fusions of 1 or 2 levels remained in the study. Length of time spent on operating, blood loss, blood transfusion, hospital stay, complications, clinical results measured by SF-36v2, and radiologic assessment of union and of loss of height of adjacent discs were analyzed and compared by means of chi2 test, t test, and Fisher exact test.

RESULTS

Statistically, there was no significant difference between the 2 groups in relation to demographics, blood loss, need of transfusion, hospital stay, complications, clinical results, rate of union, and effect on adjacent discs. The operating time needed for Group 2 was significantly shorter in than the time needed for Group 1 (P < 0.001). In Group 1, 3 of 186 screws violated the pedicle cortex requiring reoperation because root irritation versus no complication on a total of 90 screws in Group 2.

CONCLUSION

Unilateral instrumentation used for the treatment of degenerative lumbar spondylolisthesis is as effective as bilateral instrumentation when performed in addition to 1- or 2-level posterolateral fusion. The cost of this method is lower, saves time, and reduces possible risk inserting screws in only one side.

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.

A preliminary comparative study of radiographic results using mineralized collagen and bone marrow aspirate versus autologous bone in the same patients undergoing posterior lumbar interbody fusion with instrumented posterolateral lumbar fusion

BACKGROUND CONTEXT

Multiple bone graft substitutes for spinal fusion have been studied with varying results.

PURPOSE

The purpose of this study was to assess the effectiveness of a mineralized collagen matrix combined with bone marrow, versus autologous bone, in the same patients undergoing a posterior lumbar interbody fusion and an instrumented posterolateral lumbar fusion.

STUDY DESIGN/SETTING

A prospective, comparative study.

PATIENT SAMPLE

Patients indicated for one-level posterior lumbar interbody fusion and instrumented posterolateral lumbar fusion, serving as self-controls.

OUTCOME MEASURES

Thin-cut computed tomographic scans with sagittal reconstruction and plain radiographs, including lateral flexion/extension views were performed and assessed at 12 and 24 months after surgery. Oswestry Disability Index and Visual Analog Scale questionnaires were completed by all patients preoperatively and at 12 and 24 months after surgery.

METHODS

After informed consent and failure of nonoperative treatment, 25 consecutive patients requiring one-level instrumented posterolateral fusion combined with posterior interbody fusion were enrolled in the study. Mineralized collagen bone graft substitute combined with bone marrow aspirate was used on one side of the posterolateral fusion, with iliac crest autograft on the contralateral side.

RESULTS

A fusion rate of 84% (21/25) was achieved for the autologous bone grafts and 80% (20/25) for the bone graft substitute. The interbody fusion rate was 92% (23/25). Mean Oswestry Disability Index (ODI) scores decreased 57.2% at 12 months and 55.6% at 24 months, compared with baseline.

CONCLUSIONS

Mineralized collagen bone graft substitute exhibited similar radiographic results compared with autograft in this model. Further trials incorporating bilateral fusion, as well as posterolateral fusion alone without interbody fusion are warranted to confirm the results of this study.

Graft resorption with the use of bone morphogenetic protein: lessons from anterior lumbar interbody fusion using femoral ring allografts and recombinant human bone morphogenetic protein-2

STUDY DESIGN

This is a prospective cohort study examining the results and radiographic characteristics of anterior lumbar interbody fusion (ALIF) using femoral ring allografts (FRAs) and recombinant human bone morphogenetic protein-2 (rhBMP-2). This was compared to a historical control ALIF using FRAs with autologous iliac crest bone graft (ICBG).

OBJECTIVE

To determine whether the use of rhBMP-2 can enhance fusion ALIF with stand-alone FRAs.

SUMMARY OF BACKGROUND DATA

ALIF is a well-accepted procedure in reconstructive spine surgery. Advances in spinal surgery have produced a multitude of anterior interbody implants. The rhBMP-2 has promoted fusion in patients undergoing ALIF with cages and threaded allograft dowels. The FRA still remains a traditional alternative for anterior support. However, as a stand-alone device, the FRA has fallen into disfavor because of high rates of pseudarthrosis. With the advent of rhBMP-2, the FRA may be more attractive because of its simplicity and remodeling potential. It is important to understand the implications when rhBMP-2 is used with such structural allografts.

METHODS

A total of 36 consecutive patients who underwent ALIF with stand-alone FRAs by a single surgeon (E.G.D.) at 1 institute were included. A cohort of 9 consecutive patients who received FRAs filled with rhBMP-2 was followed prospectively. After noticing suboptimal results, the senior author terminated this method of lumbar fusion. A total of 27 prior consecutive patients who received FRAs filled with autogenous ICBG were used for comparison. Analyzing sequential radiographs, flexion-extension radiographs, and computerized tomography with multiplanar reconstructions determined nonunions. Minimum follow-up was 24 months.

RESULTS

Pseudarthrosis was identified in 10 of 27 (36%) patients who underwent stand-alone ALIF with FRAs and ICBG. Nonunion rate was higher among patients who received FRAs with rhBMP-2 (i.e., 5 of 9 [56%]). Statistical significance was not established because of the early termination of the treatment group (P > 0.3). Of interest, radiographs and computerized tomography revealed early and aggressive resorption of the FRAs when used with rhBMP-2. This preceded graft fracture and even disintegration, resulting in instability and eventual nonunion.

CONCLUSION

The use of rhBMP-2 did not enhance the fusion rate in stand-alone ALIF with FRAs. In fact, the trend was toward a higher nonunion rate with rhBMP-2, although this was not significant with the numbers available. This result appears to be caused by the aggressive resorptive phase of allograft incorporation, which occurs before the osteoinduction phase.

Treatment of instability and spondylolisthesis: surgical versus nonsurgical treatment

Spondylolisthesis is a common cause of lower-back pain, radiculopathy, and neurogenic claudication among the adult population. Treatment should begin with nonoperative measures that may include physical therapy, aerobic exercise, epidural steroid injections, and homeopathic remedies. If these treatments fail, surgical intervention may provide the patient pain relief and improvement in neurologic symptoms. The use of instrumentation for posterolateral fusions as well as interbody fusion may improve clinical outcomes for those having surgical intervention. We discuss the current nonoperative modalities and surgical techniques treating degenerative spondylolisthesis.

LEVEL OF EVIDENCE

Level V: Expert Opinion. See the Guidelines for Authors for a complete description of the levels of evidence.

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 9: fusion in patients with stenosis and spondylolisthesis

The best medical evidence available in the literature confirms the utility of fusion for improving patient outcomes following decompression for stenosis associated with spondylolisthesis. The majority of evidence from other studies comparing outcomes after decompression alone or decompression combined with PLF in patients with stenosis and spondylolisthesis also favors the performance of PLF. The medical evidence regarding the use of pedicle screw fixation in this patient population is rated as Class III and is inconsistent. A consistent benefit associated with the use of pedicle screw fixation has been reported in patients with preoperative instability or kyphosis. Iatrogenic instability following decompression is associated with poor outcomes and may also be treated with PLF involving supplemental instrumentation. The precise definition of instability or kyphosis has varied among researchers and requires further study.

Lower dose of rhBMP-2 achieves spine fusion when combined with an osteoconductive bulking agent in non-human primates

STUDY DESIGN

A non-human primate lumbar intertransverse process arthrodesis model was used to evaluate the effectiveness of different formulations of recombinant human bone morphogenetic protein-2 (rhBMP-2) to induce consistent bone formation.

OBJECTIVE

To determine if the combination of rhBMP-2/absorbable collagen sponge (ACS) wrapped around a bulking agent, consisting of a biphasic calcium phosphate/collagen composite, could achieve posterolateral spine fusion with a dose of rhBMP-2 (3.0 mg/side) that previously failed to induce posterolateral fusion in rhesus monkeys with other carriers.

SUMMARY OF BACKGROUND DATA

Successful bone induction in both human and non-human primates has required higher concentrations of BMP than were required in lower order models. The Food and Drug Administration approved concentration of rhBMP-2 for interbody fusion (1.5 mg/mL) when delivered on the ACS alone without a bulking agent (doses 3-9 mg/side) has failed to induce clinically relevant amounts of bone formation in a posterolateral spine fusion model in rhesus monkeys. Previously, a higher concentration of 2.0 mg/mL of rhBMP-2 delivered on stacked sheets of a biphasic calcium phosphate ceramic/collagen compression resistant matrix (CRM) was required to achieve fusion in the rhesus monkey and was the basis for this study (doses of 6-12 mg/side).

METHODS

Nine skeletally mature, rhesus macaque monkeys underwent single level posterolateral arthrodesis at L4-L5. Two different rhBMP-2 doses were evaluated in 3 delivery configurations. The first 3 monkeys received 10 mg/side (2.5 mL at 4.0 mg/mL) of rhBMP-2 loadeddirectly onto a CRM carrier (15% hydroxyapatite/85%beta-tricalcium phosphate ceramic/collagen matrix), resulting in a final concentration of 2.0 mg/mL. The second 3 monkeys received 3 mg/side (2.0 mL at 1.5 mg/mL) of rhBMP-2 loaded directly on the CRM carrier, resulting in a 0.6 mg/mL final concentration. Three additional monkeys also received the 3 mg/side (2.0 mL at 1.5 mg/mL) of rhBMP-2 delivered on an ACS, which was then wrapped around the dry CRM matrix used as a bulking agent, yielding a 1.5 mg/mL final concentration of rhBMP-2 on the sponge wrapped around the bulking agent. The monkeys were euthanized at 24 weeks after surgery. Manual palpation, plain radiographs, computerized tomography, and nondecalcified histology were used to evaluate fusion in a blinded fashion.

RESULTS

The 3 monkeys with 10 mg rhBMP-2 placed directly on the CRM carrier (2.0 mg/mL final concentration) achieved solid fusion. The 3 monkeys that underwent fusion with 3 mg of rhBMP-2 placed directly on the CRM carrier (0.6 mg/mL final concentration) failed to achieve fusion. In contrast, the 3 monkeys that underwent fusion with the same 3 mg dose of rhBMP-2 dispensed only on an ACS that was wrapped around the CRM achieved solid bilateral fusion.

CONCLUSIONS

This study shows the importance of carrier optimization and final implant protein concentration for the successful delivery of rhBMP-2. By combining the properties of the ACS with the CRM, the required dosage of rhBMP-2 was diminished by more than 3-fold in the non-human primate model. This finding suggests that the currently available concentration of rhBMP-2 (1.5 mg/mL) could be successful for achieving posterolateral spine fusion when combined with an osteoconductive bulking agent that can support the induced new bone formation.

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.