Controversies about interspinous process devices in the treatment of degenerative lumbar spine diseases: past, present, and future

Stand-Alone Percutaneous Pedicle Screw Lumbar Fixation to Indirectly Decompress the Neural Elements in Spinal Stenosis: A Radiographic Assessment Case Series

BACKGROUND

 The ideal surgical treatment of lumbar canal stenosis remains controversial. Although decompressive open surgery has been widely used with good clinical outcome, minimally invasive indirect decompression techniques have been developed to avoid the complications associated with open approaches. The purpose of this study was to evaluate the radiologic outcome and safety of the indirect decompression achieved with stand-alone percutaneous pedicle screw fixation in the surgical treatment of lumbar degenerative pathologies.

METHODS

 Twenty-eight patients presenting with spinal degenerative diseases including concomitant central and/or lateral stenosis were treated with stand-alone percutaneous pedicle screw fixation. Radiographic measurements were made on axial and sagittal magnetic resonance (MR) images, performed before surgery and after a mean follow-up period of 25.2 months. Measurements included spinal canal and foraminal areas, and anteroposterior canal diameter.

RESULTS

 Percutaneous screw fixation was performed in 35 spinal levels. Measurements on the follow-up MR images showed statistically significant increase in the cross-sectional area of the spinal canal and the neural foramen, from a mean of 88.22 and 61.05 mm2 preoperatively to 141.52 and 92.18 mm2 at final follow-up, respectively. The sagittal central canal diameter increased from a mean of 4.9 to 9.1 mm at final follow-up. Visual analog scale (VAS) pain score and Oswestry Disability Index (ODI) both improved significantly after surgery (p < 0.0001).

CONCLUSION

 Stand-alone percutaneous pedicle screw fixation is a safe and effective technique for indirect decompression of the spinal canal and neural foramina in lumbar degenerative diseases. This minimally invasive technique may provide the necessary decompression in cases of common degenerative lumbar disorders with ligamentous stenosis.

Innovative technologies in thoracolumbar and lumbar spine surgery failing to reach standard of care: state-of-art review

PURPOSE

To evaluate previously popular technologies in the field of spine surgery, and to better understand their advantages and limitations to the current standards of care. Spine surgery is an ever-evolving field that serves to resolve various spinal pathologies in patients of all ages. While there are established treatments for various conditions, such as lumbar spinal stenosis, idiopathic scoliosis, and degenerative lumbar disease, there is always further research and development in these areas to produce innovative technologies that can lead to better outcomes. As this process progresses, we must remind ourselves of previously tried and tested inventions and their outcomes that have fallen short of becoming a standard to ensure we are able to learn lessons from the past.

METHODS

A thorough literature review was conducted with the aim of compiling literature of previously utilized technologies in spine surgery. Biomedical databases were utilized to gather relevant articles including PubMed, MEDLINE, and EMBASE. Emphasis was placed on gathering articles with technologies or therapeutics aimed at treating common spinal pathologies including lumbar spinal stenosis (LSS), adolescent idiopathic scoliosis (AIS), and other degenerative lumbar spine diseases. The keywords used were: "failed technologies", "historical technologies", "spine surgery", "spinal stenosis", "adolescent idiopathic scoliosis", and "degenerative lumbar spine disease". A total of 47 articles were gathered after initial review.

RESULTS

Different technologies pertaining to spine surgery were identified and critically evaluated. Some of these technologies included X-STOP, Vertiflex, Vertebral Body Stapling, and Dynesys. These technologies were evaluated for their strengths and limitations across their spinal pathology applications. While each type of technology had their benefits, the data tended to be mixed with various limitations across studies.

CONCLUSION

These technologies have been trialed in the field of spine surgery across various spinal pathologies, but still prove of limited efficacy and shortcomings to the current standards of care.

Advancing the design of interspinous fixation devices for improved biomechanical performance: dual vs. single-locking set screw mechanisms and symmetrical vs. asymmetrical plate designs

Background

Interspinous devices were introduced in the field of spine surgery as an alternative to traditional pedicle screw fixation in selected patients for treatment of spinal stenosis and fixation. These devices designs have evolved from non-fixated extension blocks to sophisticated interspinous fixation devices (IFDs). There is an absence of literature comparing the biomechanical fixation strength of different IFD plate designs and the role of set screw locking systems. The aim of this study was to evaluate fixation strengths by bench testing static disassembly and pullout strength of two dissimilar IFD designs and locking mechanisms. We hypothesized that the InSpan (InSpan LLC, Burlington, MA, USA) dual-locking symmetrically IFD plate designed will have stronger fixation than the Aspen (ZimVie, Parsippany, NJ, USA) single-locking asymmetric IFD plate design.

Methods

We conducted two biomechanical bench tests to evaluate the load to failure locking characteristics of symmetrical InSpan and asymmetrical Aspen IFD designs. Static pullout testing involved locking each IFD to the stainless steel and 40 pcf cellular polyurethane foam and measuring pullout load and displacement six times. Seven InSpan and two Aspen IFDs (including the "used" IFDs from the pullout testing) underwent static disassembly tests using a pair of disassembly fixtures positioned between the IFD plates to measure disassembly force and displacement. All tests were performed under ambient conditions using an INSTRON 8874 Bi-Axial Tabletop Servohydraulic Dynamic Testing System (INSTRON, Norwood, MA, USA), and data was collected at a 0.2 mm/s displacement control rate until the test was stopped when there was a drop in the continuously increasing force against resistance (gross failure).

Results

The InSpan IFD experienced 94.81% higher resistance to pullout compared to the Aspen IFD in static pullout testing (P<0.05), owing to its notably larger footprint area of 69.8%. Gross failure for both IFD implant designs occurred at the foam block-block interface. In static disassembly testing, pristine InSpan required 60.7% higher force over pristine Aspen and 401.3% for "used" IFDs. Gross failure was characterized by the gradual distraction of the plates and material removal at the set screw contact points. Implant failure at the block-implant interface emphasized the pivotal role of teeth design and the contact surface area of the plates in ensuring stability.

Conclusions

The dual-locking symmetrical InSpan IFD outperformed single-locking asymmetric Aspen IFD in both static disassembly and pullout bench tests. This highlights the benefits of InSpan's improved design and its potential for enhanced long-term stability in spinal fixation applications.

Effectiveness of Interspinous Process Devices in Managing Adjacent Segment Degeneration Following Lumbar Spinal Fusion: A Systematic Review and Meta-Analysis

Background: Adjacent segment degeneration (ASD) is a significant complication following lumbar spinal fusion, often necessitating further surgical interventions and impairing patient outcomes. Interspinous process devices were introduced as an alternative treatment for spinal stenosis and degenerative spondylolisthesis and can potentially reduce the incidence of ASDd. This systematic review and meta-analysis aims to evaluate the effectiveness of interspinous process devices or IPDs in managing ASD following a previous spinal fusion compared to traditional fusion techniques. Methods: Electronic databases, including PubMed, Embase, and the Cochrane Library, were queried for studies assessing IPDs against traditional lumbar fusion methods for managing ASD after previous lumbar fusion, which had been published between January 2014 and the present. Statistical analysis was conducted using Review Manager 5.4. Results: Seven retrospective cohort studies involving 546 patients met the inclusion criteria. The analysis revealed that IPDs were associated with a statistically significant reduction in the incidence of ASD (OR = 0.28, 95% CI: 0.16 to 0.51, p < 0.0001, and I2 = 0% after excluding outliers). The ODI demonstrated a non-significant trend towards improved outcomes with IPDs at the 2-year follow-up (SMD = -3.94; 95% CI: -11.72 to 3.85). Range of motion (ROM) was better preserved with IPDs compared to fusion (SMD = 0.00, 95% CI: -0.41 to 0.41, p = 1.00, I2 = 60%). The visual analogue scale or VAS lower back pain scores were significantly reduced at the 2-year follow-up (SMD = -0.69, 95% CI: -1.18 to -0.19, p = 0.006, and I2 = 74%). VAS leg pain showed consistent improvements (SMD = -0.29; 95% CI: -0.63 to 0.04). Intraoperative blood loss was significantly lower with IPDs (SMD = -2.07; 95% CI: -3.27 to -0.87, p = 0.0007, and I2 = 95%), and operation times were shorter (SMD = -2.22, 95% CI: -3.31 to -1.12, p < 0.0001, and I2 = 94%). Conclusions: The judicious use of IPDs might benefit a subset of patients, particularly those who are not suitable candidates for major corrective surgery.

24-Month Outcomes of Indirect Decompression Using a Minimally Invasive Interspinous Fixation Device versus Standard Open Direct Decompression for Lumbar Spinal Stenosis: A Prospective Comparison

Purpose

An early-stage, multi-centre, prospective, randomised control trial with five-year follow-up was approved by Health Research Authority to compare the efficacy of a minimally invasive, laterally implanted interspinous fixation device (IFD) to open direct surgical decompression in treating lumbar spinal stenosis (LSS). Two-year results are presented.

Patients and Methods

Forty-eight participants were randomly assigned to IFD or decompression. Primary study endpoints included changes from baseline at 8-weeks, 6, 12 and 24-months follow-ups for leg pain (visual analogue scale, VAS), back pain (VAS), disability (Oswestry Disability Index, ODI), LSS physical function (Zurich Claudication Questionnaire), distance walked in five minutes and number of repetitions of sitting-to-standing in one minute. Secondary study endpoints included patient and clinician global impression of change, adverse events, reoperations, operating parameters, and fusion rate.

Results

Both treatment groups demonstrated statistically significant improvements in mean leg pain, back pain, ODI disability, LSS physical function, walking distance and sitting-to-standing repetitions compared to baseline over 24 months. Mean reduction of ODI from baseline levels was between 35% and 56% for IFD (p<0.002), and 49% to 55% for decompression (p<0.001) for all follow-up time points. Mean reduction of IFD group leg pain was between 57% and 78% for all time points (p<0.001), with 72% to 94% of participants having at least 30% reduction of leg pain from 8-weeks through 24-months. Walking distance for the IFD group increased from 66% to 94% and sitting-to-standing repetitions increased from 44% to 64% for all follow-up time points. Blood loss was 88% less in the IFD group (p=0.024) and operating time parameters strongly favoured IFD compared to decompression (p<0.001). An 89% fusion rate was assessed in a subset of IFD participants. There were no intraoperative device issues or re-operations in the IFD group, and only one healed and non-symptomatic spinous process fracture observed within 24 months.

Conclusion

Despite a low number of participants in the IFD group, the study demonstrated successful two-year safety and clinical outcomes for the IFD with significant operation-related advantages compared to surgical decompression.

Pacific Spine and Pain Society (PSPS) Evidence Review of Surgical Treatments for Lumbar Degenerative Spinal Disease: A Narrative Review

INTRODUCTION

Interventional treatment options for the lumbar degenerative spine have undergone a significant amount of innovation over the last decade. As new technologies emerge, along with the surgical specialty expansion, there is no manuscript that utilizes a review of surgical treatments with evidence rankings from multiple specialties, namely, the interventional pain and spine communities. Through the Pacific Spine and Pain Society (PSPS), the purpose of this manuscript is to provide a balanced evidence review of available surgical treatments.

METHODS

The PSPS Research Committee created a working group that performed a comprehensive literature search on available surgical technologies for the treatment of the degenerative spine, utilizing the ranking assessment based on USPSTF (United States Preventative Services Taskforce) and NASS (North American Spine Society) criteria.

RESULTS

The surgical treatments were separated based on disease process, including treatments for degenerative disc disease, spondylolisthesis, and spinal stenosis.

CONCLUSIONS

There is emerging and significant evidence to support multiple approaches to treat the symptomatic lumbar degenerative spine. As new technologies become available, training, education, credentialing, and peer review are essential for optimizing patient safety and successful outcomes.

Biomechanical investigation of a customized interspinous spacer system in the treatment of degenerative disc diseases: A finite element analysis

BACKGROUND

A novel interspinous fixation system based on anatomical parameters and incorporating transfacetopedicular screws, was developed to treat degenerative disc diseases. The biomechanical characteristics of the novel system were evaluated using finite element analysis in comparison to other classical interspinous spacers.

METHODS

The L1-S1 lumbar spine finite element models were surgically implanted with the novel system, Coflex and DIAM devices at the L4/L5 segment to assess the range of motion, the pression distribution of intervertebral disc, the peak stresses on the spinous process and implant during various motions.

FINDINGS

Range of motions of the L4/L5 surgical segment were reduced by 29.13%, 61.27%, 77.35%, 33.33%, and the peak stresses of intervertebral disc were decreased by 36.82%, 67.31%, 73.00%, 69.57% for the novel system in flexion, extension, lateral bending, and axial rotation when compared with the Coflex, and they were declined by 34.53%, 57.86%, 75.81%, 25.21%; 36.22%, 67.31%, 75.01%, 71.40% compared with DIAM. The maximum stresses of the spinous process were 29.93 MPa, 24.66 MPa, 14.45 MPa, 24.37 MPa in the novel system, and those of Coflex and DIAM were 165.3 MPa, 109 MPa, 84.79 MPa, 47.66 MPa and 52.59 MPa, 48.78 MPa, 50.27 MPa, 44.16 MPa during the same condition.

INTERPRETATION

Compared to other interspinous spacer devices, the novel interspinous fixation system demonstrated excellent stability, effectively distributing load on the intervertebral disc, and reducing the risk of spinous process fractures. The personalized design of the novel interspinous fixation system could be a viable option for treating degenerative disc diseases.

Characterizing utilization patterns and reoperation risk factors of interspinous process devices: analysis of a national claims database

INTRODUCTION

Interspinous process devices (IPDs) were developed as minimally invasive alternatives to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates, there has been minimal adoption by spine surgeons. This study leveraged a national claims database to characterize national IPD usage patterns and postoperative outcomes after IPD implantation.

METHOD

Using the PearlDiver database, we identified all patients who underwent 1- or 2-level IPD implantation between 2010 and 2018. Univariate and multivariable logistic regression was performed to identify predictors of the number of IPD levels implanted and reoperation up to 3 years after the index surgery. Right-censored Kaplan-Meier curves were plotted for duration of reoperation-free survival and compared with log-rank tests.

RESULTS

Patients (n = 4865) received 1-level (n = 3246) or 2-level (n = 1619) IPDs. Patients who were older (adjusted odds ratio [aOR] 1.02, 95% confidence interval [CI] 1.01-1.03, P < .001), male (aOR 1.31, 95% CI 116-1.50, P < .001), and obese (aOR 1.19, 95% CI 1.05-1.36, P < .01) were significantly more likely to receive a 2-level IPD than to receive a 1-level IPD. The 3-year reoperation rate was 9.3% of patients when mortality was accounted for during the follow-up period. Older age decreased (aOR 0.97, 95% CI 0.97-0.99, P = .0039) likelihood of reoperation, whereas 1-level IPD (aOR 1.37, 95% CI 1.01-1.89, P = .048), Charlson Comorbidity Index (aOR 1.07, 95% CI 1.01-1.14, P = .018), and performing concomitant open decompression increased the likelihood of reoperation (aOR 1.68, 95% CI 1.35-2.09, P = .0014).

CONCLUSION

Compared with 1-level IPDs, 2-level IPDs were implanted more frequently in older, male, and obese patients. The 3-year reoperation rate was 9.3%. Concomitant open decompression with IPD placement was identified as a significant risk factor for subsequent reoperation and warrants future investigation.

Is the interspinous process device safe and effective in elderly patients with lumbar degeneration? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND CONTEXT

Lumbar spinal stenosis is one of the most common diseases affecting the elderly that is characterized by the narrowing of the spinal canal and peripheral neural pathways which may cause back pain and neurogenic intermittent claudication in affected patients. Recently, as an alternative treatment between conservative therapy and decompression surgery, interspinous process device (IPD) such as X-stop, Coflex, DIAM, Aperius, Wallis, etc., has gained enough popularity.

PURPOSE

The purpose of this study was to evaluate the efficacy and safety of IPD in the treatment of degenerative lumbar spinal stenosis compared with decompression surgery.

STUDY DESIGN

This study was a systematic review and meta-analysis of randomized controlled trials.

PATIENT SAMPLE

555 patients' samples were collected for this study.

OUTCOME MEASURES

The Visual Analogue Scale and the Oswestry Disability Index were analyzed, as well as the Zurich Claudication Questionnaire For efficacy evaluation. Complication and reoperation rate was utilized for the assessment of safety.

METHODS

A comprehensive literature search was performed through Pubmed, EMBASE, Web of Science, and Cochrane Library until October 2023. Among the studies meeting the eligible criteria, any study in which IPD was utilized in the treatment of degenerative lumbar spinal stenosis was included in the current review. For efficacy evaluation, the Visual Analogue Scale and the Oswestry Disability Index were analyzed, as well as the Zurich Claudication Questionnaire. Complication and reoperation rates were utilized for the assessment of safety.

RESULTS

Five randomized controlled trials with 555 patients were included. There were no significant differences in VAS leg pain (SMD - 0.08, 95% CI - 0.32 to 0.15) and back pain (SMD 0.09, 95%CI-0.27 to 0.45), ODI scores (MD 1.08, 95% CI - 11.23 to 13.39) and ZCQ physical function (MD-0.09, 95% CI-0.22 to 0.05) for IPD compared with decompression surgery. In terms of ZCQ symptom severity (MD - 0.22, 95% CI - 0.27 to - 016), decompression surgery showed superior to the IPD. As for complications (RR 1.08, 95% CI 0.36 to 3.27), the IPD had no advantages compared to decompression surgery, whereas inferior to it in reoperation rate (RR 2.58, 95% CI 1.67 to 3.96).

CONCLUSIONS

This systematic review and meta-analysis indicated no superiority in the clinical outcome for IPD compared with decompression surgery. However, more clinical studies are warranted to determine the efficacy and safety of IPD.

Bibliometric analysis of interspinous device in treatment of lumbar degenerative diseases

In recent years, with the introduction of the concept of lumbar non-fusion, the interspinous device has emerged. The purpose of this study is to bibliometrically analyze the state, areas of interest, and emerging trends in the usage of interspinous devices for the treatment of lumbar degeneration disease, as well as related research fields. Between January 1, 2000 and June 14, 2023, a comprehensive collection of publications on the topic of interspinous devices in the treatment of lumbar degenerative disease (IDTLDD) was procured from the Web of Science. A bibliometric analysis and visualization were subsequently conducted, utilizing various tools including HisCite, VOSviewer, CiteSpace, and bibliometrix package. This process involved the gathering of data on the country, institution, author, journal, reference, and keywords. A comprehensive analysis of 401 publications sourced from 149 journals was conducted, with 1718 authors affiliated with 1188 institutes across 240 countries/regions. Notably, the United States emerged as the leading contributor with 134 published articles on interspinous devices in the treatment of lumbar degenerative disease (33.42%). The most productive institution was Capital Medical University, with (10, 2.49%) publications. The author with the highest publication output was Block, Jon E, with 10 publications. European Spine Journal demonstrated the highest level of productivity, with a publication of (n = 39, 9.73%). The term "X-Stop" was the most frequently utilized keyword, followed by "Lumbar spinal stenosis." The study identified various topics of current interest, such as "Invasive decompression" and "Coflex." The present study provides a comprehensive survey of research trends and developments in the application of interspinous device for the treatment of lumbar degenerative diseases, including relevant research findings and collaborative efforts among authors, institutions, and countries.

15-year survivorship analysis of an interspinous device in surgery for single-level lumbar disc herniation

BACKGROUND

Interspinous devices have been introduced as alternatives to decompression or fusion in surgery for degenerative lumbar diseases. This study aimed to investigate 15-year survivorship and risk factors for reoperation of a Device for Intervertebral Assisted Motion (DIAM) in surgery for 1-level lumbar disc herniation (LDH).

METHODS

A total of 94 patients (54 men and 40 women) underwent discectomy and DIAM implantation for 1-level LDH, with a mean follow-up of 12.9 years (range, 6.3-15.3 years). The mean age was 46.2 years (range, 21-65 years). Sixty-two patients underwent DIAM implantation for L4-5, 27 for L5-6, and 5 for L3-4. Reoperations due to any reason associated with DIAM implantation level or adjacent levels were defined as failure and used as the end point of determining survivorship.

RESULTS

During the 15-year follow-up, 8 patients (4 men and 4 women) underwent reoperation due to recurrence of LDH at the DIAM implantation level, a reoperation rate of 8.5%. The mean time to reoperation was 6.5 years (range, 0.8-13.9 years). Kaplan-Meier analysis showed a cumulative survival rate of the DIAM implantation of 97% at 5 years, 93% at 10 years, and 92% at 15 years after surgery; the cumulative reoperation rate of the DIAM implantation was 3% at 5 years, 7% at 10 years, and 8% at 15 years after surgery. Mean survival time was predicted to be 14.5 years (95% CI, 13.97-15.07). The log-rank test and Cox proportional hazard model showed that age, sex, and location did not significantly affect the reoperation rate of DIAM implantation.

CONCLUSIONS

Our results showed that DIAM implantation significantly decreased reoperation rate for LDH in the 15-year survivorship analysis. We suggest that DIAM implantation could be considered a useful intermediate step procedure for LDH surgery. To the best of our knowledge, this is the longest follow-up study in which surgical outcomes of interspinous device surgery were reported.

A Radiological Evaluation of Lumbar Spinous Processes and Interspinous Spaces, Including Clinical Implications

Background and objective

The aim of this study was the examination of morphometry of the spinous process (SP) and interspinous space (ISS) of the lumbar region to help provide a basis for the design and implantation of interspinous devices.

Methods

Between 2017 and 2019, 215 individuals underwent magnetic resonance imaging of the lumbar region for various reasons. No pathology was detected in these images, and the participants' age, height, and weight information when available were included in the study. From these images, the height and length of the SP and ISS in the lumbar region were noted. The heights of the SP and ISS were measured at three levels as anterior, middle, and posterior (respectively, anterior height of the spinous process [AHSP], middle height of the spinous process [MHSP], as well as posterior height of the spinous process [PHSP] for the height of SP, and anterior ISS, middle ISS and posterior ISS for the height of ISS). All measurements were compared according to the gender, age, weight, height, and body mass index of the individuals.

Results

The level with the lowest SP height and length was L5 vertebra. The ISS height and length were lowest at L4-L5. In addition, we observed a statistically significant difference at multiple levels with age, weight, height, and body mass index of the reference ranges.

Conclusion

We think that these changes should be considered when designing and implanting interspinous devices. Since there are few studies examining all these correlations, we think that the results of this study will make a unique contribution to the literature.

Current concepts of spondylosis and posterior spinal motion preservation for radiologists

Spinal fusion is performed to eliminate motion at a degenerated or unstable segment. However, this is associated with loss of motion at the fused levels and increased stress on adjacent levels. Motion-preserving implants have been designed in effort to mitigate the limitations of fusion. This review will focus on posterior spinal motion-preserving technologies. In the cervical spine, laminoplasty is a posterior motion-preserving procedure used in the management of myelopathy/cord compression. In the lumbar spine, motion-sparing systems include interspinous process devices (also referred to as interspinous process spacers or distraction devices), posterior dynamic stabilization devices (also referred to as pedicle screw/rod fixation-based systems), and posterior element replacement systems (also referred to as total facet replacement devices). Knowledge of the intended physiologic purpose, hardware utilized, and complications is important in the assessment of imaging in those who have undergone posterior motion preservation procedures.

Interspinous Process (ISP) Devices in Comparison to the Use of Traditional Posterior Spinal Instrumentation

A systematic literature review was conducted on studies comparing interspinous process (ISP) devices to traditional methods of posterior spinal instrumentation (pedicle screw-rod construct), in terms of indications of use, complications, pain assessment, estimated blood loss, length of hospital stay, reoperation rates, and return to work. The objective was to analyze, evaluate and summarize the current published literature on the proposed efficacy and clinical and surgical long-term outcomes of the ISP device in comparison to the traditional posterior spinal instrumentation (pedicle screw-rod construct). The ISP device is a minimally invasive and less disruptive alternative to traditional methods of posterior spinal instrumentation (pedicle screw-rod construct). However, very few published literature studies to date have reported the comparison of ISPs in terms of efficacy and clinical and surgical outcomes, to traditional posterior spinal instrumentation. A systematic literature review was performed in PubMed and Google Scholar to evaluate the results of published research that meet the defined inclusion and exclusion criteria and to analyze clinical indications and surgical outcomes of the ISP device compared to traditional methods of posterior spinal instrumentation (pedicle screw-rod construct). Inclusion criteria included keywords such as "ISP device, ISP, posterior spinal instrumentation, pedicle screw fixation, bilateral pedicle screws, interbody fusion with posterior spinal instrumentation, lumbar spinal stenosis, and posterior lumbar stability." No exclusion criteria keywords were included in this literature review. ISPs provide a high degree of spinal stability in multiple planes, including a decreased range of motion restriction in flexion-extension, and comparable results to bilateral pedicle screw (BPS) in axial rotation. The use of the ISP device in adjunct with an interbody fusion, ensures less estimated operative blood loss (EBL), shorter operative time, less bony exposure without the need for extensive soft tissue or muscle retraction, a decrease in the rate of pseudoarthrosis, and a shorter length of hospital stay (LOHS) when compared to the traditional posterior instrumentation (pedicle screw-rod construct). Based on the various published literature reviews noted throughout this research paper, it is safe to conclude, that an ISP device that is accompanied by interbody fusion, including posterior approaches posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF); anterior approaches such as anterior interbody fusion (ALIF), and lateral approaches including direct lateral interbody fusion (DLIF), lateral lumbar interbody fusion (LLIF), extreme lateral interbody fusion (XLIF), is considered a credible and an effective minimally invasive option for the treatment of mild to moderate lumbar stenosis and stable low-grade spondylolisthesis (less than two) when compared to the traditional posterior spinal instrumentation of a pedicle screw-rod construct. Surgeons that are relatively new to the ISP technologies for spinal instrumentation would likely benefit from more clinical and surgical evidence of safety and efficacy in published peer-reviewed medical literature. Further clinical trials are needed to manifest the efficacy of ISPs regarding postoperative outcomes when compared to traditional posterior instrumentation techniques (pedicle screw-rod construct) with adjunct interbody fusions.

Determination of Work Relative Value Units for Management of Lumbar Spinal Stenosis by Open Decompression and Interlaminar Stabilization

BACKGROUND

Effective January 1, 2017, open surgical decompression and interlaminar stabilization (ILS) received a Category I Current Procedural Terminology (CPT®) code 22867. The current work relative value units (wRVUs) assigned to the procedure of 13.5 are not reflective of the amount of work involved. During the survey process, CPT® 22867 was erroneously assessed with a percutaneous "sister" code (CPT® 22869), which is performed with no decompression (but within the same new "family") and primarily by nonsurgeons. However, similar CPT® code descriptors assigned to each of these new codes undermined their procedural differences during the survey process and generated confusion among physician survey responders, the American Medical Association/Specialty Society Relative Value Scale Update Committee (RUC), and ultimately the Centers for Medicare and Medicaid Services (CMS) regarding the value of ILS. The resulting physician payment determination for the ILS procedure has had severe deleterious effects on this procedure being offered to lumbar spinal stenosis (LSS) patients. Our independent society-driven survey presents new data that assess the accuracy of the assigned wRVUs for CPT® 22867.

METHODS

An independent survey was driven by the International Society for the Advancement of Spine Surgery (ISASS) in November 2018 and sent to 58 US surgeons with experience performing open decompression with ILS (CPT® 22867) and without financial conflicts of interest as analogous to RUC survey financial disclosure requests. Respondents were asked to compare CPT® 22867 with a list of 10 other comparator CPT® codes reflective of common spine surgeries. The survey presented each comparator CPT® code with its code descriptor and corresponding wRVUs alongside the code descriptor for CPT® 22867. A patient vignette was also provided that describes a typical clinical scenario for the surveyed procedure. Respondents were then asked to indicate which comparator CPT® code on the reference list is most similar to the survey code descriptor and typical patient/service vignette provided, as well as specify estimated wRVUs for CPT® 22867 relative to their selected comparator CPT® code. The surgeons' responses were analyzed to determine comparator CPT® codes and estimated wRVUs.

RESULTS

Among the 28 surgeons who responded to the survey, both open decompression codes (57.1%) and fusion codes (42.9%) were chosen as most similar to the typical patient/service for CPT® 22867. Furthermore, the laminectomy procedure (CPT® 63047) was chosen as the surveyed surgeons' model response for a reference procedure in terms of similar work intensity and time for CPT® 22867. After calculating the difference between the selected comparator codes and estimated wRVUs, nearly all respondents had a positive calculated difference, indicating that surgeons selected wRVUs lower than they deemed appropriate as a result of the listed CPT® codes they were required to use. In the spirit of the Rasch analysis, the regression analysis estimated wRVUs for CPT® 22867 that are greater than its assigned wRVUs (13.5) and its most comparable procedure (CPT® 63047; reference wRVUs: 15.37).

DISCUSSION AND CONCLUSIONS

The survey results indicate that the wRVUs assigned to CPT® 22867 are significantly undervalued at 13.50 and have directly resulted in the underreimbursement for surgeons performing the ILS procedure. This misvaluation of the code has created a supply-and-demand anomaly in which the rate of ILS procedures has flatlined despite increasing rates of fusion procedures and an increasing older population. This anomaly is a cause of concern for policy makers and the health care community for the future of safeguarding patient welfare and procedural innovation. Therefore, understanding the clinical economic impact and appropriately addressing potential misvalued codes, such as the ILS procedure, are critical to protecting the future of patient care.

Effect of different designs of interspinous process devices on the instrumented and adjacent levels after double-level lumbar decompression surgery: A finite element analysis

Recently, various designs and material manufactured interspinous process devices (IPDs) are on the market in managing symptomatic lumbar spinal stenosis (LSS). However, atraumatic fracture of the intervening spinous process has been reported in patients, particularly, double or multiple level lumbar decompression surgery with IPDs. This study aimed to biomechanically investigate the effects of few commercial IPDs, namely DIAM^TM, Coflex^TM, and M-PEEK, which were implanted into the L2-3, L3-4 double-level lumbar spinal processes. A validated finite element model of musculoskeletal intact lumbar spinal column was modified to accommodate the numerical analysis of different implants. The range of motion (ROM) between each vertebra, stiffness of the implanted level, intra stress on the intervertebral discs and facet joints, and the contact forces on spinous processes were compared. Among the three implants, the Coflex system showed the largest ROM restriction in extension and caused the highest stress over the disc annulus at the adjacent levels, as well as the sandwich phenomenon on the spinous process at the instrumented levels. Further, the DIAM device provided a superior loading-sharing between the two bridge supports, and the M-PEEK system offered a superior load-sharing from the superior spinous process to the lower pedicle screw. The limited motion at the instrumented segments were compensated by the upper and lower adjacent functional units, however, this increasing ROM and stress would accelerate the degeneration of un-instrumented segments.

Transforaminal Endoscopic Discectomy Combined With an Interspinous Process Distraction System for Spinal Stenosis

BACKGROUND

The combination of the percutaneous transforaminal endoscopic decompression (PTED) with an interspinous process distraction system (IPS) may offer additional benefit in the treatment of spinal stenosis in patients who have failed nonsurgical treatment.

METHODS

We retrospectively reviewed the medical records of 33 patients diagnosed with lumbar stenosis and radiculopathy and treated them with transforaminal endoscopic lumbar decompression between 2013 and 2017. Primary outcome measures were modified Macnab as well as preoperative and postoperative visual analog scale (VAS) criteria and the Oswestry Disability Index (ODI). Only patients with a minimum follow-up of 2 years were included.

RESULTS

A total of 28 patients were treated with a combination of PTED and percutaneous IPS (group A), and 5 patients were treated with PTED and mini-open IPS (group B). In group A patients, there was a 4.48 reduction in the VAS score. The ODI changed from 50.25 preoperatively to 18.2 postoperatively, and excellent and good Macnab outcomes were obtained in 78% of patients. In group B patients, the mean VAS reduction was 5.2 points. The ODI changed from 44.34 preoperatively to 14.62 postoperatively, and 80% of group B patients achieved excellent and good Macnab outcomes. No complications related to PTED or IPS were observed throughout the 2-year follow-up.

CONCLUSIONS

The addition of IPS to the PTED procedure in select patients may offer additional benefits to patients being treated for lumbar lateral stenosis and foraminal stenosis with low-grade spondylolisthesis.

LEVEL OF EVIDENCE

3.

CLINICAL RELEVANCE

Feasibility study.

New combination of IntraSPINE device and posterior lumbar interbody fusion for rare skipped-level lumbar disc herniation: a case report and literature review

Posterior lumbar interbody fusion is an open surgical technique that has been widely used for the treatment of degenerative lumbar disease. However, traditional lumbar spinal fusion, especially long-segment fusion surgery, is associated with several complications. The IntraSPINE (Cousin Biotech, Wervicq-Sud, France) is a new device for non-fusion lumbar spine surgery that is used as an alternative for the treatment of degenerative lumbar disease. Although the designer of the IntraSPINE proposed indications for its use, including combination of the device with lumbar spinal fusion for the treatment of degenerative lumbar disease, use of the IntraSPINE has not been reported in the clinical literature. In the present case, we boldly combined the IntraSPINE device and posterior lumbar interbody fusion for the treatment of skipped-level lumbar disc herniation to explore the indications of the IntraSPINE and report its clinical outcomes.

Degenerative Lumbar Spinal Stenosis

Degenerative lumbar spinal stenosis is the most frequent cause of low back pain and/or sciatica in the elderly patient. Epidemiology, pathophysiology, clinical manifestations and testing are reviewed in a wide current bibliographic investigation. The importance of the relationship between clinical presentation and imaging study, especially magnetic resonance imaging (MRI), is emphasized. Prior to treatment indication, it is necessary to identify the precise location of pain, as well as the differential diagnosis between neurological and vascular lameness. Conservative treatment combining medications with various physical therapy techniques solves the problem in most cases, while therapeutic testing with injections, whether epidural, foraminal or facetary, is performed when pain does not subside with conservative treatment and before surgery is indicated. Injections usually perform better results in relieving sciatica symptoms and less in neurological lameness. Equine tail and/or root decompression associated or not with fusion is the gold standard when surgical intervention is required. Fusion after decompression is necessary in cases with segmental instability, such as degenerative spondylolisthesis. When canal stenosis occurs at multiple levels and is accompanied by axis deviation, whether coronal and/or sagittal, correction of axis deviations should be performed in addition to decompression and fusion, especially of the sagittal axis, in which a lumbar lordosis correction is required with techniques that correct the rectified lordosis to values close to the pelvic incidence.

An Algorithmic Approach to Treating Lumbar Spinal Stenosis: An Evidenced-Based Approach

OBJECTIVE

Lumbar spinal stenosis (LSS) can lead to compression of the neural and vascular elements and is becoming more common due to degenerative changes that occur because of aging processes. Symptoms may manifest as pain and discomfort that radiates to the lower leg, thigh, and/or buttocks. The traditional treatment algorithm for LSS consists of conservative management (physical therapy, medication, education, exercise), often followed by epidural steroid injections (ESIs), and when nonsurgical treatment has failed, open decompression surgery with or without fusion is considered. In this review, the variables that should be considered during the management of patients with LSS are discussed, and the role of each treatment option to provide optimal care is evaluated.

RESULTS

This review leads to the creation of an evidence-based practical algorithm to aid clinicians in the management of patients with LSS. Special emphasis is directed at minimally invasive surgery, which should be taken into consideration when conservative management and ESI have failed.

Cost-effectiveness and Safety of Interspinous Process Decompression (Superion)

Objective

There are several treatment options for patients suffering from lumbar spinal stenosis, including surgical and conservative care. Interspinous spacer decompression using the Superion device offers a less invasive procedure for patients who fail conservative treatment before traditional decompression surgery. This review assesses the current cost-effectiveness, safety, and performance of lumbar spinal stenosis treatment modalities compared with the Superion interspinous spacer procedure.

Methods

EMBASE and PubMed were searched to find studies reporting on the cost-effectiveness, safety, and performance of conservative treatment, including medicinal treatments, epidural injections, physical therapy, and alternative methods, as well as surgical treatment, including laminectomy, laminectomy with fusion, and interspinous spacer decompression. Results were supplemented with manual searches.

Results

Despite substantial costs, persistent conservative treatment (>12 weeks) of lumbar spinal stenosis showed only minimal improvement in pain and functionality. When conservative treatment fails, surgery is more effective than continuing conservative treatment. Lumbar laminectomy with fusion has considerably greater cost than laminectomy alone, as the length of hospital stay increases, the costs for implants are substantial, and complications increase. Although laminectomy and the Superion have comparable outcomes, the Superion implant is positioned percutaneously. This approach may minimize the direct and indirect costs of outpatient rehabilitation and absenteeism, respectively.

Conclusions

Superion interspinous lumbar decompression is a minimally invasive procedure for patients with lumbar spinal stenosis who have failed conservative treatment. Compared with extending conservative treatment or traditional spinal surgery, interspinous lumbar decompression reduces the direct and indirect costs associated with lumbar spinal stenosis.

How I do it: step-by-step BacJac™ posterior interspinous spacer placement

BACKGROUND

BacJac™ is a posterior interspinous spacer for selected cases of degenerative lumbar spine diseases. It blocks the metameric vertebral segment in terminal extension, restoring foraminal heights.

METHODS

The authors provide a detailed step-by-step description of the surgical technique, shedding light on surgical tips and pitfalls of this procedure. An accurate pre-operative patient selection is analyzed, defining meticulously surgical indications. A high-quality video of the surgical procedure is provided.

CONCLUSION

BacJac™ interspinous device allows a safe, mini-invasive, and effective treatment of selected cases of degenerative lumbar spine disease.

Mobility-Preserving Surgery for Lumbar Spinal Stenosis: WFNS Spine Committee Recommendations

Background

Although decompression is the basis of surgical treatment for lumbar spinal stenosis (LSS), under various circumstances instrumented fusion is performed as well. The rationale for mobility-preserving operations for LSS is preventing adjacent segment disease (ASD). We review the rationale for mobility preservation in ASD and discuss related topics such as indications for fusion and the evolving role of minimally invasive approaches to lumbar spine decompression. Our focus is on systematic review and consensus discussion of mobility-preserving surgical methods as related to surgery for LSS.

Methods

Groups of spinal surgeons (members of the World Federation of Neurosurgical Societies Spine Committee) performed systematic reviews of dynamic fixation systems, including hybrid constructs, and of interspinous process devices; consensus statements were generated based on the reviews at 2 voting sessions by the committee several months apart. Additional review of background data was performed, and the results summarized in this review.

Results

Decompression is the basis of surgical treatment of LSS. Fusion is an option, especially when spondylolisthesis or instability are present, but indications remain controversial. ASD incidence reports show high variability. ASD may represent the natural progression of degenerative disease in many cases. Older age, poor sagittal balance, and multilevel fusion may be associated with more ASD. Dynamic fixation constructs are treatment options that may help prevent ASD.

An evaluation of the host response to an interspinous process device based on a series of spine explants: Device for Intervertebral Assisted Motion (DIAM®)

Background

The objective of this study was to evaluate the host response to an interspinous process device [Device for Intervertebral Assisted Motion (DIAM^®)] based on a series of nine spine explants with a mean post-operative explant time of 35 months.

Methods

Explanted periprosthetic tissues were processed for histology and stained with H&E, Wright-Giemsa stain, and Oil Red O. Brightfield and polarized light microscopy were used to evaluate the host response to the device and the resultant particulate debris. The host response was graded per ASTM F981-04. Quantitative histomorphometry was used to characterize particle size, shape, and area per ASTM F1877-05. The presence or absence of bone resorption was also evaluated when bony tissue samples were provided.

Results

Periprosthetic tissues demonstrated a non-specific foreign body response composed of macrophages and foreign body giant cells to the DIAM^® device in most of the accessions. The foreign body reaction was not the stated reason for explantation in any of the accessions. Per ASTM F981-04, a "very slight" to "mild" to "moderate" chronic inflammatory response was observed to the biomaterials and particulate, and this varied by tissue sample and accession. Particle sizes were consistent amongst the explant patients with mean particle size on the order of several microns. Osteolysis, signs of toxicity, necrosis, an immune response, and/or device related infection were not observed.

Conclusions

Cyclic loading of the spine can cause wear in dynamic stabilization systems such as DIAM^®. The fabric nature of the DIAM^® device's polyethylene terephthalate jacket coupled with the generation of polymeric particulate debris predisposes the device to a foreign body reaction consisting of macrophages and foreign body giant cells. Although not all patients are aware of symptoms associated with a foreign body reaction to a deeply implanted device, surgeons should be aware of the host response to this device.

The MIST Guidelines: The Lumbar Spinal Stenosis Consensus Group Guidelines for Minimally Invasive Spine Treatment

BACKGROUND

Lumbar spinal stenosis (LSS) can lead to compression of neural elements and manifest as low back and leg pain. LSS has traditionally been treated with a variety of conservative (pain medications, physical therapy, epidural spinal injections) and invasive (surgical decompression) options. Recently, several minimally invasive procedures have expanded the treatment options.

METHODS

The Lumbar Spinal Stenosis Consensus Group convened to evaluate the peer-reviewed literature as the basis for making minimally invasive spine treatment (MIST) recommendations. Eleven consensus points were clearly defined with evidence strength, recommendation grade, and consensus level using U.S. Preventive Services Task Force criteria. The Consensus Group also created a treatment algorithm. Literature searches yielded 9 studies (2 randomized controlled trials [RCTs]; 7 observational studies, 4 prospective and 3 retrospective) of minimally invasive spine treatments, and 1 RCT for spacers.

RESULTS

The LSS treatment choice is dependent on the degree of stenosis; spinal or anatomic level; architecture of the stenosis; severity of the symptoms; failed, past, less invasive treatments; previous fusions or other open surgical approaches; and patient comorbidities. There is Level I evidence for percutaneous image-guided lumbar decompression as superior to lumbar epidural steroid injection, and 1 RCT supported spacer use in a noninferiority study comparing 2 spacer products currently available.

CONCLUSIONS

MISTs should be used in a judicious and algorithmic fashion to treat LSS, based on the evidence of efficacy and safety in the peer-reviewed literature. The MIST Consensus Group recommend that these procedures be used in a multimodal fashion as part of an evidence-based decision algorithm.

Utilization of Interspinous Devices Throughout the United States Over a Recent Decade: An Analysis of the Nationwide Inpatient Sample

STUDY DESIGN

Retrospective database study.

OBJECTIVES

Analysis of economic and demographic data concerning interspinous device (ID) placement throughout the United States to improve value-based care and health care utilization.

METHODS

The National Inpatient Sample (NIS) database was queried for patients who underwent insertion of an interspinous process spinal stabilization device (ICD-9-CM 84.80) between 2008 and 2014 across 44 states. Demographic and economic data were obtained which included the annual number of surgeries, age, sex, insurance type, location, and frequency of routine discharge. The NIS database represents a 20% sample of discharges from US hospitals, which is weighted to provide national estimates.

RESULTS

There was a 73% decrease in ID implanted from 2008 to 2014. The mean cost associated with insertion of the device increased 28% from $13 653 in 2008 to $17 515 in 2014. The mean length of stay (LOS) increased from 1.8 to 2.4 days. Patients aged 45 to 64 years increased from 14.1% to 34.3% while patients aged 65 to 84 years decreased from 74.4% to 60.6%. By region, 34% of ID placement occurred in the South followed by 19.7% that occured in the Northeast. When stratifying by median income for patient zip code, the procedure was performed more in cities designated as higher rather than lower income areas (74.2% and 19.5%, respectively).

CONCLUSIONS

Throughout the United States, there was a progressive decline in the insertion of interspinous spacers by 73% over the study period. The total costs for the procedure increased by 28% while the aggregate national charges decreased by 55.6% between 2008 and 2014.

Comparison of two FDA-approved interspinous spacers for treatment of lumbar spinal stenosis: Superion versus X-STOP-a meta-analysis from five randomized controlled trial studies

BACKGROUND

Decompressive laminectomy (DI) is a standard operation for lumbar spinal stenosis (LSS) patient with severe claudication symptoms for many years. However, patients whose symptom severity does not meet undergoing invasive surgery make therapeutic options into dilemma. Interspinous spacers (ISP) bridge the gap between surgical interventions and CC in management of LSS. In our study, we aim to systematically assess the two FDA-approved interspinous spacers for treatment of lumbar spinal stenosis: Superion versus X-STOP.

METHODS

Electronic databases, including PubMed, Embase, MEDLINE, Cochrane Library were searched to retrieve clinical trials concerning the comparison between Superion and X-STOP in treatment for lumbar spinal stenosis before April 2017. The following outcome measures were extracted: (1) Zurich Claudication Questionnaire (ZCQ) patient satisfaction score, (2) axial pain severity, (3) extremity pain severity, (4) back-specific functional impairment, (5) reoperation, and (6) complication. The data analysis was conducted with Review Manager 5.3.

RESULTS

Five randomized controlled trials (RCTs) with 1118 patients were included in this meta-analysis. The pooled analysis indicated that the Superion group is superior to X-STOP in axial pain severity (SMD: 0.03; 95% CI 0.15, 0.45; p < 0.0001, I² = 41%, p = 0.16), ZCQ patient satisfaction score (SMD: 0.23; 95% CI 0.08, 0.38; p = 0.002, I² = 0%, p = 0.61). However, Superion group showed similarity outcome in extremity pain severity (SMD: 0.18; 95% CI - 0.06, 0.43; p = 0.14, I² = 62%, p = 0.05), back-specific functional impairment (SMD: 0.04; 95% CI - 0.10, 0.19; p = 0.56, I² = 0%, p = 0.77), reoperation rate (RR: 1.10; 95% CI 0.82, 1.48; p = 0.51, I² = 19%, p = 0.30), and complication (RR: 0.98; 95% CI 0.63, 1.53; p = 0.92, I² = 0%, p = 0.83).

CONCLUSION

Both the Superion and X-STOP interspinous spacers can relieve symptoms of LSS. In addition, the Superion spacer may represent a promising spacer for patient with LSS. As we know, the effectiveness and safety of ISP is still considered investigational and unfavor clinical results in the medical literature may continue to limit the appeal of IPS to many surgeons in the future. However, because of the advantage of IPS technique, it will win a wide place in the future degenerative lumbar microsurgery.

Surgical treatment of bilateral nondisplaced isthmic lysis by interlaminar fixation device

STUDY DESIGN

Spondylolysis is a defect in the portion of pars interarticularis. The latter affects approximately 6% of the population. It is caused by repetitive trauma in hyperextension. Low back pain is the most common symptom.

METHODS

We implanted interspinous process devices in 12 patients with isthmic lysis without spondylolisthesis for low back pain. The purpose of the surgery was to conduct a minimally invasive procedure.

RESULTS

In eight cases, patients became asymptomatic. In two cases, there has been a considerable improvement. In two cases, no change had been noted.

CONCLUSION

This good result motivates us to consider this approach a part of therapeutic arsenal for some cases of spondylolysis.

Survival analysis of the Wallis interspinous spacer used as an augment to lumbar decompression

OBJECT

The Wallis fixed interspinous spacer may augment traditional decompression in the treatment of lumbar spinal stenosis. The aim of this study was to determine factors influencing survival of the Wallis interspinous spacer and to identify specific modes and predictors of failure.

METHODS

We performed a retrospective cohort study of 244 Wallis interspinous spacers implanted in 195 consecutive patients with a mean age of 56 years (range 21-87) to augment single or multi-level decompression. We examined patient demographics, indications for surgery, surgical techniques and pathology on magnetic resonance imaging (MRI). A Kaplan-Meier survival analysis was performed.

RESULTS

Median follow-up was 4.5 years (range 2-8). Sixteen patients were lost to follow-up. Repeat MRI was performed in 98 patients (50%). A recurrent stenosis was found in 21% of patients (41/195) and occurred at a similar incidence at the level of the spacer and at adjacent spinal levels. Revision decompression was performed in 19 patients (10%) at 2.8 ± 1.8 years (range 6 months-6 years) with implant removal in 15 and conversion to fusion in 4 patients. No specific patient factors or pre-operative MRI findings predicted failure. Five-year survival was 91% (95% CI: 79-96%).

CONCLUSIONS

The Wallis implant is generally implanted without complication when used as an adjunct to decompression with a good medium term survival. Though disc heights were maintained, the Wallis spacer did not however appear to reduce the incidence of recurrent spinal or foraminal stenosis from that expected from decompression alone.

Interspinous implants to treat spinal stenosis

PURPOSE OF REVIEW

Lumbar spinal stenosis has historically been treated with open decompressive surgery which is associated with significant morbidity and may give rise to various complications. Interspinous spacers (ISS) have been developed as a less invasive strategy which may serve to avoid many of these risks. The two current spacers that are FDA approved and commercially available are the Coflex and Superion devices. The goal is to review these two implants, their indications, and patient selection.

RECENT FINDINGS

The Coflex device has been shown to be analogous to decompression and fusion when treating moderate spinal stenosis. It provides dynamic stability after a decompression is performed, without the rigidity of pedicle-screw instrumentation. Recent results show improved outcomes in Coflex patients at 3 years of follow-up, as compared to decompression and fusion. The Superion implant is placed percutaneously in the interspinous space with minimal disruption of spinal anatomy. When compared to the X-Stop device (which is no longer available), the Superion implant shows improved outcomes at 3 years of follow-up. ISS are lesser invasive options as compared to formal decompression and fusion for the treatment of lumbar spinal stenosis.

Change of sagittal spinal alignment and its association with pain and function after lumbar surgery augmented with an interspinous implant

BACKGROUND

Interspinous spacer/implants like the Device for Intervertebral Assisted Motion (DIAM™) are controversially yet commonly used in the surgical treatment of lumbar degenerative pathologies. Criticism is based on ill-defined indications, lack of superiority over decompression, and a poorly understood mechanical effect. Yet, continued use by surgeons implies their perceived clinical merit. We examined radiographic spinal alignment for 12 months, and pain and function for 24 months, after DIAM-augmented surgery to improve the understanding of the mechanical effect relating to clinical outcomes in patients.

METHODS

We undertook a single-surgeon prospective, longitudinal study of 40 patients (20 F, 20 M) who received DIAM-augmented surgery in treatment of their symptomatic lumbar degenerative condition. Outcomes measured included sagittal spinal alignment (lumbar lordosis, sacral inclination, primary (PDA), supradjacent (SDA) disc angles, and regional sagittal balance (RSB; standing lateral radiographs), and back and leg pain (visual analogue scale; VAS) and function (Oswestry Disability Index; ODI). Responders were identified as those with clinically meaningful improvement to pain (>20%) and function (>15%) at 24 months postoperatively; features of sagittal spinal alignment between responders and non-responders were examined.

RESULTS

Sagittal alignment was unchanged at 12 months. At 6 weeks postoperatively, PDA (mean (SD)) reduced by 2.2° (4.0°; p < 0.01) and more-so in back pain non-responders (3.8° (3.2°)) than responders (0.7° (4.4°); p < 0.05). Positive preoperative RSB in responders (26.7Rmm (42.3Rmm); Rmm is a system-relative measure) decreased at 6 weeks (by 3.1Rmm (9.1Rmm)). Non-responders had a negative RSB preoperatively (-1.0Rmm (32.0Rmm)) and increased at 6 weeks (11.2Rmm (15.5Rmm); p < 0.05). Clinically meaningful improvement for the whole cohort for back pain and function were observed to 24 months (back pain: 25.0% (28.0); function: 15.4% (17.6); both p < 0.0001).

CONCLUSIONS

Unaltered sagittal alignment at 12 months was not related to symptoms after DIAM-augmented lumbar surgery. Subtle early flattening at the index disc angle was not maintained. Preoperative and early post-operative sagittal alignment may indicate response after DIAM-augmented surgery for mixed lumbar pathologies. Further investigation toward defining indications and patient suitability is warranted.

Evaluation of Coflex interspinous stabilization following decompression compared with decompression and posterior lumbar interbody fusion for the treatment of lumbar degenerative disease: A minimum 5-year follow-up study

Few studies have compared the clinical and radiological outcomes between Coflex interspinous stabilization and posterior lumbar interbody fusion (PLIF) for degenerative lumbar disease. We compared the at least 5-year clinical and radiological outcomes of Coflex stabilization and PLIF for lumbar degenerative disease. Eighty-seven consecutive patients with lumbar degenerative disease were retrospectively reviewed. Forty-two patients underwent decompression and Coflex interspinous stabilization (Coflex group), 45 patients underwent decompression and PLIF (PLIF group). Clinical and radiological outcomes were evaluated. Coflex subjects experienced less blood loss, shorter hospital stays and shorter operative time than PLIF (all p<0.001). Both groups demonstrated significant improvement in Oswestry Disability Index and visual analogue scale back and leg pain at each follow-up time point. The Coflex group had significantly better clinical outcomes during early follow-up. At final follow-up, the superior and inferior adjacent segments motion had no significant change in the Coflex group, while the superior adjacent segment motion increased significantly in the PLIF group. At final follow-up, the operative level motion was significantly decreased in both groups, but was greater in the Coflex group. The reoperation rate for adjacent segment disease was higher in the PLIF group, but this did not achieve statistical significance (11.1% vs. 4.8%, p=0.277). Both groups provided sustainable improved clinical outcomes for lumbar degenerative disease through at least 5-year follow-up. The Coflex group had significantly better early efficacy than the PLIF group. Coflex interspinous implantation after decompression is safe and effective for lumbar degenerative disease.

Interspinous process spacers versus traditional decompression for lumbar spinal stenosis: systematic review and meta-analysis

BACKGROUND

Interspinous spacers are used in selected patients for the treatment of lumbar spinal stenosis. The uses of interspinous devices are still debated, with reports of significantly higher reoperation rates and unfavourable cost-effectiveness compared to traditional decompression techniques.

METHODS

Six electronic databases were searched from their date of inception to December 2015. Relevant studies were identified using specific eligibility criteria and data was extracted and analyzed based on predefined primary and secondary endpoints.

RESULTS

Eleven comparative studies were obtained for qualitative and quantitative assessment, data extraction and analysis. There was no significant difference in VAS back pain, leg pain or ODI scores for standalone interspinous process device (IPD) vs. bony decompression. However, standalone IPD was associated with lower surgical complications (4% vs. 8.7%, P=0.03) but higher long-term reoperation rates (23.7% vs. 8.5%, P<0.00001). IPD as an adjunct to decompression had comparable patient-reported scores, complications and reoperation rates to decompression alone.

CONCLUSIONS

Current evidence indicates no superiority for mid- to long-term patient-reported outcomes for IPD compared with traditional bony decompression, with lesser surgical complications but at the risk of significantly higher reoperation rates and costs.

Lumbar lateral shift in a patient with interspinous device implantation: a case report

BACKGROUND

Lumbar lateral shift (LLS) is a common clinical observation but has rarely been described in a patient with a history of lumbar surgery. The purpose of the current case report was to describe the use of the McKenzie Method of Mechanical Diagnosis and Therapy (MDT) in the multi-modal treatment of a patient with an LLS and a history of multiple surgical procedures in the lumbar spine, including interspinous process device (IPD) implantation.

CASE DESCRIPTION

A 72-year-old female with chronic low back pain (LBP) and a surgical history in the lumbar spine was referred to physical therapy for radiating leg pain and presented with a right LLS. Her chief complaints included sitting for long periods, vacuuming and ascending stairs into her home.

OUTCOMES

The patient was treated during eight visits over 30 days. Treatment interventions included manual shift correction, self-correction and management, joint mobilisation below the level of IPD implantation ,neurophysiology education, and development of a home exercise programme. At discharge, her leg pain was resolved and all goals had been met. The patient reported maintenance of gains at 6-month follow-up.

DISCUSSION

Utilisation of the MDT approach, including LLS correction, produced positive outcomes in a complex patient with previous IPD implantation. Future research should investigate treatment and outcomes after invasive spinal procedures in similar patient populations to better inform clinical management.

LEVEL OF EVIDENCE

4.

INTERSPINOUS SPACER IN PERSISTENT DISCOGENIC PAIN: PERCUTANEOUS APPROACH OR OPEN TECHNIQUE

ABSTRACT Objective: To compare the postoperative clinical course of placement of interspinous spacer with open technique (ISO) with percutaneous interspinous spacer (PIS). Methods: Quasi-experimental, longitudinal study of 42 patients with discogenic pain uncontrolled with analgesics, aged 35-55 years old, 21 women, and 21 men. Clinical history, location of pain, VAS scale before and after surgery, Oswestry Disability Index and Macnab modified scale at 6 months were used. Results: When performing quantitative analysis statistical significance (p = 0.0478, 0.0466, 0.0399) was demonstrated with Student's t test between the results according to VAS scale; in the qualitative analysis with the Oswestry index and Macnab modified scale it was demonstrated the hypothesis that the results is dependent of the surgical technique. Conclusions: According to the results, we can conclude that there is a statistically significant difference depending on the surgical technique used with respect to the rate of disability and functionality in daily life as well as in the improvement of pain symptoms.

Interspinous process devices for the treatment of neurogenic intermittent claudication: a systematic review of randomized controlled trials

The aim of this study is to compare interspinous process device (IPD) implantation to other methods for the treatment of neurogenic intermittent claudication (NIC). PubMed and Cochrane library were searched in December 2014. Randomized controlled trials (RCTs) comparing IPD implantation and nonoperative therapy or laminectomy with/without spinal fusion for the treatment of NIC due to spinal stenosis or low-grade degenerative spondylolisthesis were included. Meta-analysis and qualitative analysis were conducted as appropriate. Eleven articles (eight RCTs) were included, with two having high risk of bias. These RCTs were divided into three groups according to control cohort interventions: IPD implantation was compared with nonoperative treatment (group 1, n = 3), laminectomy (group 2, n = 3), and laminectomy associated with instrumented spinal fusion (group 3, n = 2). Group 1 studies reported better Zurich Claudication Questionnaire (ZCQ) scores for the IPD group. In group 2, two studies reported comparable ZCQ scores and one revealed comparable visual analog scale (VAS) and Oswestry Disability Index (ODI) scores; pooled analysis showed a higher reoperation rate in patients treated with IPD. In group 3, one study found that more patients in IPD group gained more than 25 % improvement in VAS and ODI, with lower complication rate; the other reported better ZCQ scores in the IPD group and comparable complication and reoperation rates. IPD implantation is more effective than the other methods, but not superior to laminectomy in treating NIC.

The cost effectiveness of dynamic and static interspinous spacer for lumbar spinal stenosis compared with laminectomy

BACKGROUND

The present study aims to evaluate the cost-effectiveness of Dynamic Interspinous Spacer (Coflex®) and Static Spacer (X-STOP ®) compared to Laminectomy (LAMI) in patients with lumbar spinal stenosis.

METHODS

A decision-analysis model was developed to estimate the cost-effectiveness. The effectiveness parameters were obtained from a systematic literature review in relevant databases including PUBMED and EMBASE. A meta-analysis was performed using the STATA statistical package and a random model was used to collect measures of mean difference of visual analogue scale (VAS) pain score before and after intervention in X-stop, Coflex and LAMI (95% confidence intervals). Cost data were obtained from provider and associated literature based on health care provider prospective. We assumed that the probability of the success rate of surgery in each intervention from associated literature and calculated Incremental cost effectiveness ratio. A one-way sensitivity analysis was also carried out.

RESULTS

Twenty-four out of 294 studies are included in the Meta-analysis. The overall pooled estimate of the mean difference of VAS pain score were 3.49 (95% CI 3.7-4.2) and 4.14 (95% CI 3.09- 5.19) for X-stop and Coflex, respectively. In addition, we assumed the overall pooled estimate of 5.3 (95% CI 2.15-7.4) on the basis of literature for LAMI. The average cost per LAMI surgery, X-stop and Coflex was US$ 3019, US$ 2022 and US$ 2566, respectively. Incremental cost effectiveness ratio of X-stop and Coflex versus LAMI was US$ 665.9 and US$ 780.7, respectively.

CONCLUSION

Static Interspinous Spacer (X-stop) appears to be the most cost-effective treatment strategy in base case scenario with success rate of LAMI (range between (55%-70%). A sensitivity analysis shows that the increase probability of success rate of LAMI was more than 70 % and less than 55% which lead to the cost effectiveness of the Coflex intervention.

Interspinous spacers versus posterior lumbar interbody fusion for degenerative lumbar spinal diseases: a meta-analysis of prospective studies

PURPOSE

Our aim is to evaluate the safety and effectiveness of interspinous spacers versus posterior lumbar interbody fusion (PLIF) for degenerative lumbar spinal diseases.

METHODS

A comprehensive literature search was performed using PubMed, Web of Science and Cochrane Library through September 2015. Included studies were performed according to eligibility criteria. Data of complication rate, post-operative back visual analogue scale (VAS) score, Oswestry Disability Index (ODI) score, estimated blood loss (EBL), operative time, length of hospital stay (LOS), range of motion (ROM) at the surgical, proximal and distal segments were extracted and analyzed.

RESULTS

Ten studies were selected from 177 citations. The pooled data demonstrated the interspinous spacers group had a lower estimated blood loss (weighted mean difference [WMD]: -175.66 ml; 95 % confidence interval [CI], -241.03 to -110.30; p < 0.00001), shorter operative time (WMD: -55.47 min; 95%CI, -74.29 to -36.65; p < 0.00001), larger range of motion (ROM) at the surgical segment (WMD: 3.97 degree; 95%CI, -3.24 to -1.91; p < 0.00001) and more limited ROM at the proximal segment (WMD: -2.58 degree; 95%CI, 2.48 to 5.47; p < 0.00001) after operation. Post-operative back VAS score, ODI score, length of hospital stay, complication rate and ROM at the distal segment showed no difference between the two groups.

CONCLUSIONS

Our meta-analysis suggested that interspinous spacers appear to be a safe and effective alternative to PLIF for selective patients with degenerative lumbar spinal diseases. However, more randomized controlled trials (RCT) are still needed to further confirm our results.

Use of subtransverse process polyester bands in pediatric spine surgery: a case series of 4 patients with a minimum of 12 months' follow-up

OBJECT In a previous study, the authors reported on their experience with the use of sublaminar polyester bands as part of segmental spinal constructs. However, the risk of neurological complications with sublaminar passage of instrumentation, such as spinal cord injury, limits the use of this technique. The present study reports the novel use of subtransverse process polyester bands in posterior instrumented spinal fusions of the thoracic and lumbar spines and sacrum or ilium in 4 patients. METHODS The authors retrospectively reviewed the demographic and procedural data of patients who had undergone posterior instrumented fusion using subtransverse process polyester bands. RESULTS Four patients, ranging in age from 11 to 22 years, underwent posterior instrumented fusion for neuromuscular scoliosis (3 patients) and thoracic hyperkyphosis (1 patient). There were 3 instances of transverse process fracture, with application and tensioning of the polyester band in 1 patient. Importantly, there was no instance of spinal cord injury with subtransverse process passage of the polyester band. The lessons learned from this technique are discussed. CONCLUSIONS This study has shown the "Eleghia" technique of passing subtransverse process bands to be a technically straightforward and neurologically safe method of spinal fixation. Pedicle screws, laminar/pedicle/transverse process hooks, and sublaminar metal wires/bands have been incorporated into posterior spinal constructs; they have been widely reported and used in the thoracic and lumbar spines and sacrum or ilium with varying success. This report demonstrates the promising results of hybrid posterior spinal constructs that include the Eleghia technique of passing subtransverse process polyester bands. This technique incorporates technical ease with minimal risk of neurological injury and biomechanical stability.

Interspinous process stabilization with Rocker via unilateral approach versus X-Stop via bilateral approach for lumbar spinal stenosis: a comparative study

BACKGROUND

Rocker is a novel interspinous process stabilization (IPS) that can be installed via unilateral approach by virtue of its unique design. This controlled study compared the clinical outcome of Rocker versus X-Stop to access the feasibility and validity of the novel IPS.

METHODS

From March 2011 to September 2012, 32 patients treated with Rocker and 30 patients treated with X-Stop were enrolled in this study. The primary clinical outcome measure was Oswestry Disability Index (ODI) score. The secondary clinical outcome measure was Japanese orthopaedics association (JOA) score. Disc height index (DHI) and foraminal height index (FHI) were measured for postoperative radiographic evaluation. Implant failures were also recorded.

RESULTS

There were 55 patients with complete data during 24 months follow-up. Among the 55 patients, 38 patients underwent IPS in combination with microdecompression. At the final follow-up, 49 patients achieved a minimal clinical important difference (≥ 8 points ODI improvement). The mean operative time was 53.6 min (range, 30 to 90 min) in Rocker group and 63.1 min (range, 30 to 100 min) in X-Stop group. The average blood loss was 111 ml (range, 50 to 400 ml) in Rocker group and 138 ml (range, 50 to 350 ml) in X-Stop group. ODI score were significantly improved from preoperative 46.8 ± 9.2 to 12.2 ± 2.6 at 24 months follow-up in the Rocker group and from preoperative 45.8 ± 9.8 to 11.8 ± 2.4 at 24 months follow-up in the X-Stop group. JOA score also improved significantly in both groups. The radiographic parameters of DHI and FHI in both groups increased immediately postoperatively, however, the improvements seemed to revert toward initial value during follow-up. Two patients in Rocker group demonstrated implant dislocation within one week postoperatively and one patient in X-Stop group demonstrated implant migration at two months postoperatively.

CONCLUSIONS

Preliminary clinical and radiographic outcome was similar between Rocker and X-Stop group. For patients of lumbar spinal stenosis with unilateral nerve root involved or mild-to-moderate central canal stenosis, Rocker offers a new alternative with less damage.

Failure rates and complications of interspinous process decompression devices: a European multicenter study

OBJECT

Spacers placed between the lumbar spinous processes represent a promising surgical treatment alternative for a variety of spinal pathologies. They provide an unloading distractive force to the stenotic motion segment, restoring foraminal height, and have the potential to relieve symptoms of degenerative disc disease. The authors performed a retrospective, multicenter nonrandomized study consisting of 1108 patients to evaluate implant survival and failure modes after the implantation of 8 different interspinous process devices (IPDs).

METHODS

The medical records of patients who had undergone placement of an IPD were retrospectively evaluated, and demographic information, diagnosis, and preoperative pain levels were recorded. Preoperative and postoperative clinical assessments in the patients were based on the visual analog scale. A minimum of 3 years after IPD placement, information on long-term outcomes was obtained from additional follow-up or from patient medical and radiological records.

RESULTS

One thousand one hundred eight patients affected by symptomatic 1- or 2-level segmental lumbar spine degenerative disease underwent placement of an IPD. The complication rate was 7.8%. There were 27 fractures of the spinous process and 23 dura mater tears with CSF leakage. The ultimate failure rate requiring additional surgery was 9.6%. The reasons for revision, which always involved removal of the original implant, were acute worsening of low-back pain or lack of improvement (45 cases), recurrence of symptoms after an initial good outcome (42 cases), and implant dislocation (20 cases).

CONCLUSIONS

The IPD is not a substitute for a more invasive 3-column fusion procedure in cases of major instability and spondylolisthesis. Overdistraction, poor bone density, and poor patient selection may all be factors in the development of complications. Preoperatively, careful attention should be paid to bone density, appropriate implant size, and optimal patient selection.

Characterization of lumbar spinous process morphology: a cadaveric study of 2,955 human lumbar vertebrae

BACKGROUND CONTEXT

Despite the interest in lumbar spinous process (SP)-based surgical innovation, there are no large published studies that have characterized the morphometry of lumbar SPs.

PURPOSE

To provide accurate level-specific morphometric data with respect to human lumbar SPs using a human cadaveric lumbar spine model and to describe the morphometric variation of lumbar SPs with respect to gender, race, and age.

STUDY DESIGN

An anatomic observational study.

METHODS

This study used 2,955 cadaveric lumbar vertebrae from 591 adult spines at the Hamann-Todd Human Osteological Collection. Specimens were aged 20 to 79 years. Each vertebra was photographed in standardized positions and measured using ImageJ software. Direct measurements were made for the SP length, width, height, slope, and caudal morphology. Gender, race, and age were recorded and analyzed.

RESULTS

Spinous process length was 24.8±4.6 mm (L5) to 33.9±3.9 mm (L3). Effective length varied from 19.5±2.6 mm (L1) to 24.6±3.3 mm (L4). Height was shortest at L5 (18.2±2.7 mm). Caudal width was greater than the cranial width. Slope, caudal morphology, and radius measures showed large interspecimen variation. Slope at L5 was steeper than other levels (23.7°±10.5°, p<.0001). Most specimens demonstrated convex caudal morphology. L4 had the highest proportion of convexity (80.7%). L1 was the only level with predominantly concave morphology. Measurements for female SPs were smaller, but the slope was steeper. Anatomic and effective SP lengths were longer for specimens from white individuals. Specimens from black individuals had larger width and height, as well as steeper slope. Black specimens had more convex morphology at L4 and L5. With increasing age, the SP length, effective length, and width increased. Height increased with age only at L4 and L5. Slope and caudal radius of curvature decreased with age, and increasingly convex morphology was noted at most levels.

CONCLUSIONS

This large cadaveric study provides level-specific morphometric data regarding the osseous dimensions of lumbar SPs relevant to techniques and devices targeting the lumbar SPs or the interspinous space. Of particular importance is the recognition that L5 has relatively different morphology when compared with more cranial levels. Potentially important differences were noted comparing women with men, black with white, and aging populations.

Role of IL-17 in nucleus pulposus cell proliferation and metabolism cultured in vitro

OBJECTIVE

To explore the role of cytokine, interleukin-17 (IL-17) in human degenerative disc disease.

METHODS

Through magnetic resonance imaging, human degenerative disc tissues were confirmed from the isolated nucleus pulposus cells, which were then cultured in vitro. The cells were cultured with and without different concentrations of IL-17. 2 ng/mL, 5 ng/mL, 10 ng/mL, 15 ng/mL and 20 ng/mL IL-17 concentrations were used for stimulation. After 72 hours, the inhibition rate of proliferation was measured by MTS method. For 48 and 96 hours, the nucleus pulposus cells were cultured with and without the appropriate IL-17 concentrations. The mRNA and protein expression levels of the matrix macromolecules and degrading tissue genes were measured by Real-time PCR and Western blot analysis.

RESULTS

It was noted that nucleus pulposus cell proliferation was inhibited after culturing in vitro with IL-17 stimulation, and it was further observed that the inhibition effect was significantly stronger with 15 ng/mL IL-17 concentration. With the dosage of 15 ng/mL, IL-17 stimulation induced multiple cellular responses, such as the significant increase in mRNA expression for both aggrecan (ACAN) and type I collagen (COLLA1) genes (P<0.05), and the significant decrease in mRNA expression of both degrading tissue genes, MMP3 and TIMP3 (P<0.05). Western blot results also showed that the protein level of COL1A1 was significantly decreased (t=3.199, P=0.006), while the protein level of one peptidases (ADAMTS5) significantly increased (t=2.667, P=0.021).

CONCLUSIONS

These findings suggest that IL-17 can inhibit proliferation and affect the metabolism of the cultured nucleus pulposus cells in vitro, and these findings could possibly contribute to the degenerative changes that occur in DDD through extracellular matrix synthesis inhibition, promoting nucleus pulposus extracellular matrix degradation and disrupting the metabolic balance.