Interspinous Process Research Articles

MRI evaluation of dural sac enlargement by interspinous process spacers in patients with lumbar spinal stenosis: Does it play a role in the long term?

BackgroundTo investigate dural sac enlargements and spinal alignments in patients who underwent indirect decompression with interspinous spacers. MethodsThe subjects were 20 patients who underwent indirect decompression using an interspinous spacer (X-STOP) without laminectomy. Of these 20 patients, 1 patient underwent implant removal surgery 1 month after X-STOP surgery and two patients dropped out. Ultimately, 17 patients were included in this study. MRI and X-ray images were investigated before surgery, 1 week after surgery, 3 months after surgery, and 2 years after surgery. ResultsOn MRI, the mean cross-sectional areas of the dural sac were 52.7 mm2 before surgery, 73.2 mm2 1 week after surgery, 62.4 mm2 3 months after surgery, and 58.3 mm2 2 years after surgery. There was a significant 37% increase at 1 week postoperatively compared with that before surgery, but there were no significant differences between 3 months postoperatively and 2 years postoperatively. The disc angle in an extension posture was significantly decreased at 1 week after surgery compared with that before surgery, but there were no significant differences between before surgery, 3 months after surgery, and 2 years after surgery. ConclusionsThe interspinous process spacer increased the dural sac area by 37% 1 week after surgery, but the enlargement was not maintained at 3 months or 2 years after surgery. The use of interspinous process spacers produced an enlargement of the dural sac by limiting extension of the stenotic level only. However, its effect diminished 2 years after surgery.

Posterior Cervical Muscle-Preserving Interspinous Process Approach and Decompression: More Minimally Invasive and Modified Shiraishi's Selective Laminectomy

The cervical extensor musculature is important in cases of neck pain and loss of cervical lordosis after laminoplasty. Therefore, various surgical methods have been developed to preserve the muscle during laminoplasty. We have developed a posterior cervical muscle-preserving interspinous process (MIS) approach and decompression method. We have described the operation details and clinical outcomes of selected patients who have undergone this procedure. The MIS approach and decompression method were performed in 20 consecutive patients who had only required central decompression for cervical stenosis. This procedure includes an approach to the interspinous space that is similar to Shiraishi's method but includes decompression without fracturing the spina bifida. The patients had no complications and did not require conversion to conventional laminoplasty. The mean operative time and mean blood loss was 53.0 minutes and 63.0 mL per level, respectively, and the mean hospital stay was 4.0 days. The mean preoperative and 3-month postoperative modified Japanese Orthopedic Association scores were 12.6 and 16.2, and the mean preoperative and 3-month postoperative neck disability index scores were 15.4 and 2.5, respectively. The postoperative neck visual analog scale score was 0.8. The mean preoperative and postoperative sagittal vertical axis was 1.6 and 1.8 cm, respectively. The mean loss of lordosis was 1.0°, and the mean cervical range of motion did not change from preoperatively to postoperatively. The MIS approach and decompression method was less invasive than both conventional laminoplasty and Shiraishi's selective laminectomy. It is a safe and effective minimally invasive technique for central stenosis caused by cervical spondylotic myelopathy.

155. Interspinous process decompression with the Superion® Spacer for lumbar spinal stenosis: real world experience from a device registry

BACKGROUND CONTEXT Interspinous process decompression (IPD) with stand-alone spacers has demonstrated excellent long-term clinical benefit for patients with lumbar spinal stenosis (LSS). PURPOSE Real-world experience with interspinous process decompression. The primary aim of the registry is to prospectively collect a set of perioperative and clinical outcomes among patients treated with stand-alone IPD for symptomatic LSS. STUDY DESIGN/SETTING Stand-alone IPD using the Superion Indirect Decompression System (Vertiflex, Carlsbad, CA USA). Perioperative and clinical data were captured via a registry for patients treated with IPD for LSS with intermittent neurogenic claudication. Seventy-five physicians at 53 clinical sites in the US participated. Outcomes included intraoperative blood loss, procedural time, leg and back pain severity, self-defined functional objective, and patient satisfaction at 3 weeks, 6 and 12 months. PATIENT SAMPLE To date, 722 patients have undergone IPD and enrolled in the PRESS registry with a mean age of 73.0 ± 10.7 years including 379 females (53%). The maximum number of patients providing pain severity data was 603, 521, 184 and 53 at baseline, 3 weeks, 6 and 12 months, respectively. OUTCOME MEASURES Patient-reported outcomes included leg and back pain severity by 100 mm Visual Analog Scale prior to IPD as well as at 3 weeks, 6 and 12 months, postoperatively. At each follow-up interval, patients were also asked to indicate the extent to which they had achieved their Self-Defined Functional Objective, on a 1 to 5 scale, with 1 indicating no progress at all, and 5 indicating complete achievement. Additionally, patient satisfaction with IPD was queried as satisfied, somewhat satisfied, somewhat dissatisfied, or dissatisfied. Treatment approval with IPD was characterized as definitely yes, probably yes, probably not or definitely not with respect to whether the patient would repeat the treatment. METHODS Perioperative and clinical data were captured via a registry for patients treated with IPD for LSS with intermittent neurogenic claudication. RESULTS To date, 722 patients have undergone IPD and enrolled in this registry with a mean age of 73.0 ± 10.7 years including 379 females (53%). Average intraoperative blood loss was 6.1 ± 7.7 mL; median operative duration was 39.0 minutes (range: 7.0 to 210.0 mins). Mean leg pain severity decreased from 67.3 ± 26.5 mm preoperatively to 28.7 ± 33.0 mm at 12 months, reflecting an overall 57% improvement. Corresponding responder rates were 64% (335 of 521), 61% (113 of 184) and 66% (35 of 53) at 3 weeks, 6 and 12 months, respectively. Back pain severity improved similarly from 67.9 ± 25.9 mm preoperatively to 28.6 ± 31.3 mm at 12 months (58% improvement); 12-month responder rate of 64% (34 of 53). Functional objective responder rates were 63%, 67% and 81% at 3 weeks, 6 and 12 months, respectively. For patient satisfaction at 3 weeks, 6 and 12 months, 89%, 84%, and 91% were satisfied or somewhat satisfied with their treatment and 91%, 80%, and 87% would definitely or probably undergo the same treatment again. In a phone survey, the rate of revision or reoperation was 4% (21 of 517). CONCLUSIONS These registry findings support the clinical adoption of IPD in patients considering minimally-invasive options to manage chronically recalcitrant LSS symptoms. FDA DEVICE/DRUG STATUS Superion Indirect Decompression System (Approved for this indication).

250. Interspinous process distraction compared to nonoperative care for moderate lumbar degenerative disc disease: results of the FDA IDE clinical trial

BACKGROUND CONTEXT Interspinous process distraction (IPD) devices aim to alleviate back and leg pain by limiting extension and unloading the 3-joint complex at the affected lumbar level. IPDs may offer a treatment option for painful degenerative disc disease (DDD) that is not yet indicated for fusion or disc replacement. PURPOSE To compare the safety and effectiveness of IPD and nonoperative treatment after 2 years for the treatment of moderate lumbar DDD. STUDY DESIGN/SETTING A prospective, randomized, controlled FDA IDE clinical trial at 23 US centers (ClinicalTrials.gov: NCT00456378). PATIENT SAMPLE A total of 278 patients with moderate low back pain for less than 1 year and radiographic evidence of single-level DDD between L2 and L5 who failed at least 6 weeks but less than 6 months of conservative management were randomized and treated with investigational IPD (n=181) or control nonoperative treatment (n=97). OUTCOME MEASURES The primary endpoint was Overall Success, a composite variable that included: 1) Oswestry Disability Index (ODI) score improvement of ≥ 15 points; and 2) no serious adverse event (AE) caused by the implant or by both the implant and surgical procedure (IPD) or caused by the nonoperative treatment (control); and 3) no secondary surgery (IPD) or treatment surgery (control) at the involved level. Additional safety and effectiveness endpoints included back and leg pain numerical (0-20) rating scales, SF-36 PCS/MCS, AEs and secondary surgeries. METHODS Investigational treatment consisted of the IPD implantation (without decompression) and nonoperative treatments, as necessary. Control treatment consisted of information/ education on low back pain, medication, physical therapy, and epidural and/or facet joint steroidal injections. Clinical and radiographic assessments were performed preoperatively, intra-operatively, and postoperatively up to 2 years. Statistical analyses used Bayesian methods with non-informative priors. Last observation was carried forward (LOCF) for patients lost to follow-up including patients receiving surgery (control crossovers) or additional surgery (IPD investigational) at the involved level. RESULTS Baseline demographic characteristics and outcomes scores were not statistically different between the two groups, except back pain (16.8 for investigational vs 16.1 for control, p=0.033). The IPD rate of Overall Success at 24-months was statistically superior to control (observed rate of 63.0% vs 13.4%, respectively; posterior probability of superiority (pps) > 99.9%). The improvement in outcomes for IPD was statistically superior to control (pps > 99.9%) for: ODI (26.4 vs 1.1), back pain (8.4 vs 1.2), leg pain (4.9 vs -1.1, PCS (12.6 vs.1.4), and MCS (4.4 vs -0.8). Spinous process bony erosion increased slowly to 33.7% (61/181) of patients but was not related to clinical outcomes. Treatment-related serious AEs in the control group were associated with increasing low back pain. Fifteen (8.3%) IPD and 34 (35.1%) control patients experienced a treatment-related serious AE. Twenty (11.0%) IPD patients had secondary surgery and 10 (10.3%) control patients had treatment surgery at the index level. After 6 months of nonoperative treatment, control patients had the option to crossover to IPD: 57 (58.8%) control patients had crossed over by 24 months. CONCLUSIONS These analyses support the superiority of this IPD over conservative care for moderate back pain in appropriately selected patients. FDA DEVICE/DRUG STATUS DIAM™ Spinal Stabilization System (Investigational/Not approved)

Toward a cure for lumbar spinal stenosis: The potential of interspinous process decompression

There is a growing impetus to treat aging as a disease in the quest to significantly extend the human life span through cellular regeneration methods. This approach, while promising, overlooks the fact that the evolutionary adaptation to bipedalism puts the human body in a distinctively vulnerable biomechanical and functional position. Orthograde human posture places unusually-high axial compressive loads on the weight-bearing joints of the skeleton, resulting in arthritic deterioration with aging. The effects are particularly robust in the lumbar spine were age-related degeneration, most commonly lumbar spinal stenosis (LSS), is ubiquitous among the elderly. It is postulated that re-establishing a favorable mechanical environment via interventions that unload the affected spinal joint complex may mitigate and potentially reverse the structural damage that is the cardinal pathoanatomical feature of this disease. The hypothesis of this paper is that a minimally-invasive surgical procedure, interspinous process decompression (IPD), which utilizes a stand-alone intervertebral spacer, effectively unloads the diseased spinal motion segment providing a healthy micro-environment to reverse and repair age-related and genetic deterioration of the spinal motion segment. Several lines of supporting evidence are provided from long-term follow-up results of a randomized controlled trial of IPD safety and effectiveness of the Superion® device including clinical outcomes, reoperation rates, opioid analgesic usage and advanced imaging utilization. All of these outcomes show uniquely-favorable trends with time that imply that the benefits of IPD are structural. The compendium of evidence suggests that IPD offers both a durable palliative effect due to direct blocking of back extension and a disease-modifying effect due to unloading of the spinal joint complex.

Percutaneous Interspinous Spacer in Spinal-Canal-Stenosis Treatment: Pros and Cons.

A comprehensive description of the literature regarding interspinous process devices (IPD) mainly focused on comparison with conservative treatment and surgical decompression for the treatment of degenerative lumbar spinal stenosis. Recent meta-analysis and articles are listed in the present article in order to establish IPD pros and cons.

Predictive Value of Computed Tomography Scan for Posterior Ligamentous Complex Injuries in Patients with Thoracolumbar Spinal Fractures.

Thoracolumbar spinal fractures include a range of injuries of various severities from simple apophyseal fractures to neurological injury and complex fractures associated with vertebral dislocation. The treatment of thoracolumbar fractures is challenging, especially due to the difficulty of evaluating the posterior ligamentous complex (PLC). The purpose of this study was to evaluate the diagnostic value of computed tomography (CT) scan in predicting PLC injuries in the patients with thoracolumbar spinal fractures referring to the referral center of spinal trauma in the east north of Iran in 2016. This retrospective study was conducted on patients with thoracolumbar injuries referring to Shahid Kamyab Hospital in Mashhad, east north of Iran, in 2016. The data were collected by entering the data of medical records into special forms. The classification of spinal fractures was accomplished using the AO Spine Classification System. According to the results, 71 (71.7%) patients were male, and the subjects had a mean age of 44.6±17.7 years. The PLC injury was observed in 28 (28.3%) patients. The PLC injury showed a significant relationship with facet joint widening, increased interspinous process distance, and spinous process avulsion fracture (P<0.05). As the findings of this study indicated, the diagnostic results of PLC injury by means of CT scan was similar to those obtained by magnetic resonance imaging in patients with thoracolumbar spinal fractures.

An Affordable and Feasible Technique for Minimally Invasive Tubular Lumbar Discectomy

The benefits of minimally invasive spine surgery are attainable only if hospitals have the financial resources to acquire essential equipment. We present a surgical approach readily available to countries where unacceptably expensive materials are the main limitation for use of minimally invasive spine surgery. This retrospective study included 30 patients who underwent minimally invasive spine surgery using syringes as dilators and retractors for posterior lumbar approaches. Inclusion criteria were lumbar radicular/back pain, degenerative disc, spondylolysis, unilateral approach, and maximum of 2 affected spine levels. Demographic characteristics, affected radicular level, diagnosis, type and length of surgery, hospital length of stay, MacNab criteria, complications, and resumption of daily activities were analyzed. Of 30 patients, 17 (56.6%) presented with S1 radicular pain. Pain was mainly due to posterolateral hernia (70%; n= 21) requiring 1-level discectomy. In 6 patients (20%), discectomy and an interspinous process device were required. One patient (3.33%) underwent 2-level discectomy. All surgeries were performed using syringes as dilators and retractors. Maximum syringe diameter used was 2 cm (20-mL syringes) in 29 patients (96.6%) and 3 cm (60-mL syringe) in 1 patient. Average length of surgery was 1.5 hours, and average hospital stay was 1.8 days. Based on MacNab criteria, excellent, good, and fair outcomes were achieved in 25 patients (83%), 3 patients (10%), and 2 patients (6.7%). Complications were observed in 5 patients (16.7%). This is a safe and feasible technique with excellent results obtained at low cost and is becoming an attractive surgical option in developing countries.

Application of an interspinous process device after minimally invasive lumbar decompression could lead to stress redistribution at the pars interarticularis: a finite element analysis

BackgroundAn interspinous process device, the Device for Intervertebral Assisted Motion (DIAM™) designed to treat lumbar neurogenic disease secondary to the lumbar spinal stenosis, it provides dynamic stabilization after minimally invasive (MI) lumbar decompression. The current study was conducted using an experimentally validated L1-L5 spinal finite element model (FEM) to evaluate the limited decompression on range of motion (ROM) and stress distribution on a neural arch implanted with the DIAM.MethodsThe study simulated bilateral laminotomies with partial discectomy at L3-L4, as well as unilateral and bilateral laminotomies with partial discectomy combined with implementation of the DIAM at L3-L4. The ROM and maximum von Mises stresses in flexion, extension, lateral bending, and axial torsion were analyzed in response to the hybrid protocol in comparison with the intact model.ResultsThe investigation revealed that decreased ROM, intradiscal stress, and facet joint force at the implant level, but considerably increased stress at the pars interarticularis were found during flexion and torsion at the L4, as well as during extension, lateral bending, and torsion at the L3, when the DIAM was implanted compared with the defect model.ConclusionThe results demonstrate that the DIAM may be beneficial in reducing the symptoms of stress-induced low back pain. Nevertheless, the results also suggest that a surgeon should be cognizant of the stress redistribution at the pars interarticularis results from MI decompression plus the application of the interspinous process device.

Biomechanical Analysis of Different Lumbar Interspinous Process Devices: A Finite Element Study

Recently, interspinous stabilization with the interspinous process device (IPD) has become an alternative to treat lumbar spinal stenosis. The biomechanical influence of different design features of IPDs on intradiscal pressure (IDP) and facet joint force (FJF) has not been fully understood. The aim of this study was to investigate the biomechanical performance of different IPDs using finite element (FE) method. A FE model of the L1-5 segments was developed and validated. Four surgical FE models were constructed by inserting different implants at the L3-4 segment (Coflex-F, DIAM, Wallis, and pedicle screw system). The 4 motion modes were simulated. The IPDs decreased range of motion (ROM) at the surgical level substantially in flexion and extension, but little influence was found in lateral bending and torsion. Compared with the DIAM and Wallis devices, the Coflex-F device showed advantages in stabilizing the surgical level, especially in flexion and extension, while it increased FJF at adjacent levels by 26%-27% in extension. Among the 3 IPDs, the DIAM device exhibited the most comparable ROM, IDP, and FJF at adjacent levels compared with the intact lumbar spine. The influence of the Wallis device was between that of the Coflex-F and DIAM devices. Compared with rigid fixation, the IPDs demonstrated less compensation at adjacent levels in terms of ROM, IDP, and FJF, which may lower the incidence of adjacent segment degeneration in the long term.

Adjustable Rigid Interspinous Process Fixation: A Biomechanical Study of Segmental Lordosis and Interbody Loading in the Lumbar Spine.

BackgroundRigid interspinous process fixation (ISPF) may serve as a minimally disruptive adjunct to lumbar interbody fusion. Previous biomechanical assessments of ISPF have demonstrated particularly advantageous outcomes in stabilizing the sagittal plane. However, ISPF has not been well characterized in regard to its impact on interbody load, which has implications for the risk of cage migration or subsidence, and sagittal alignment. The purpose of this study was to biomechanically assess in vitro the interbody load (IBL), focal lordosis (FL), and spinous process loading generated by in situ compression/distraction with a novel ISPF device capable of incremental in situ shortening/extension. Bilateral pedicle screw fixation (BPSF) was used as a control.MethodsTwo fresh frozen human lumbar spines were thawed and musculature was removed, leaving ligaments intact. Seven functional spinal units were iteratively tested, which involved a standard lateral discectomy, placement of a modified lateral cage possessing two load cells, and posterior fixation. BPSF and ISPF were performed at each level, with order of fixation was randomized. BPSF was first performed with maximum compressive exertion followed by 75% exertion to represent clinical application. The ISPF device was implanted at a neutral height and incrementally shortened/extended in situ in 1-mm increments. IBL and FL were measured under each condition. Loads on the spinous processes were estimated through bench-top mechanical calibration.ResultsNo significant differences in IBL were observed, but the ISPF device produced a significantly greater change in FL compared to the clinically relevant BPSF compression. IBL, as a function of ISPF device height, expressed linear behavior during compression and exponential behavior during distraction.ConclusionsThe novel ISPF device produced clinically effective IBL and FL, performing well in comparison to BPSF. Additionally, incremental ISPF device manipulation demonstrated predictable and clinically safe trends regarding loading of the interbody space and spinous processes.

Neurogenic Claudication: a Review of Current Understanding and Treatment Options.

With an aging population and increased prevalence of the disease, we set out to evaluate the validity of current diagnostic criteria for neurogenic claudication as well as the efficacy of the treatment options for the main cause, lumbar spinal stenosis (LSS). Epidural steroid injections (ESI) were most efficacious when the injectate is a steroid combined with lidocaine or lidocaine only. There are promising results regarding the efficacy of the minimally invasive lumbar decompression (MILD) procedure as well as interspinous process spacers (IPS) compared to surgical alternatives. Spinal cord stimulators are gaining ground as an effective alternative to surgery in patients with lumbar spinal stenosis that is not responsive to conservative measures or epidural injections. We found that there continues to be a lack of consensus on the diagnostic criteria, management, and treatment options for patients with LSS. The Delphi consensus is the most current recommendation to assist clinicians with making the diagnosis. Physical therapy, NSAIDs, gabapentin, and other conservative therapy measures are unproven in providing long-lasting relief. In patients with radicular symptoms, an ESI may be indicated when a combination of lidocaine with steroids is used or using lidocaine alone. In addition, there is not enough high-quality evidence to make a recommendation regarding the use of MILD versus interspinous spacers for neurogenic claudication. There remains a need for high-quality evidence regarding the efficacy of different conservative treatments, interventional procedures, and surgical outcomes in patients with neurogenic claudication in LSS.

Inter-spinous process distance: a novel parameter predicting segmental lordosis during posterior cervical spine deformity surgery.

To investigate the normative value of distance between the spinous processes (inter-spinous process distance, ISPD), correlations between patients' demographics and ISPD, and determine cutoff ISPD values that result in segmental lordosis in posterior cervical-thoracic arthrodesis with instrumentation. We reviewed patients with visible lower cervical and cervicothoracic spinous processes (C5-T2) on dynamic X-rays. Radiographic measurements included segmental Cobb angles (S-Cobb) and ISPD, defined as the distance between midpoints of the spinous processes. Correlations between patient demographics and ISPD were evaluated. In addition, the cutoff ISPD values that predict segmental lordosis (S-Cobb < 0°) were determined using the receiver operating characteristics (ROC) curve and linear regression model. We evaluated a total of 153 films on 51 patients. The mean ISPDs in neutral position were 16.0, 20.7, 23.2, and 26.0mm at C5/6, C6/7, C7/T1, and T1/T2, respectively There were no or only weak correlations between ISPD and age, race, height, body weight, and BMI. We observed significant difference between male and female ISPDs at C7/T1 and T1/T2 (P < 0.05). The ISPDs had moderate/strong correlations with S-Cobb at each segment (- 0.450 ≤ r ≤ - 0.705). Based on the ROC curves, the following cutoff values of ISPD provided 100% positive predictive value for segmental lordosis: < 10mm at C5-6; < 15mm at each level from C6 to T2. ISPD is a simple and useful parameter that correlates with the segmental Cobb angle. During posterior cervical deformity surgery, surgeons can intraoperatively predict adequate segmental lordosis by utilizing the vertebral level specific cutoff values of ISPD. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical testing of different posterior fusion devices on lumbar spinal range of motion

BackgroundRecent minimal-invasive posterior fusion devices are supposed to provide stability and obtain fusion in combination with interbody cages in the instrumented segment. The aim of the present study is to evaluate the primary stability of two minimal-invasive posterior prototypes compared to an established spinous process plate and standard pedicle screw instrumentation. MethodsSeven fresh frozen human cadaver lumbar spines (L2–L5) were tested in a spinal testing device with a moment of 7.5 Nm. Spinal stability was determined as mean range of motion (RoM) in the segment L3/L4 during extension-flexion, lateral bending and axial rotation. The RoM was measured during five conditions: 1. intact; 2. working prototype composed of an interspinous device and process plates; 3. an established spinous process fixation device 4. working prototype of facet fixation and 5. pedicle screw fixation. FindingsAll devices caused a significant reduction of RoM during extension-flexion. The RoM during lateral bending was significantly reduced to 37% (of intact) by pedicle screws and 68% by facet fixation prototype. During axial rotation the RoM was significantly reduced to 52% by pedicle screws and to 86% by facet fixation prototype. The other devices had no significant influence on RoM during lateral bending and axial rotation. InterpretationThe facet fixation prototype provided less primary stability compared to pedicle screws, but had significant advantages over spinous process fixation techniques. The results encourage further testing of this implant as a minimal-invasive approach for posterior fixation.

Interspinous process decompression is associated with a reduction in opioid analgesia in patients with lumbar spinal stenosis.

BackgroundLumbar spinal stenosis (LSS) causes significant pain and functional impairment, and medical management has increasingly included the prescription of opioid-based analgesics. Interspinous process decompression (IPD) provides a minimally-invasive treatment option for LSS.MethodsThis study estimated the type, dosage, and duration of opioid medications through 5 years of follow-up after IPD with the Superion Indirect Decompression System (Vertiflex Inc., Carlsbad, CA USA). Data were obtained from the Superion-treatment arm of a randomized controlled noninferiority trial. The prevalence of subjects using opiates was determined at baseline through 60 months. Primary analysis included all 190 patients randomized to receive the Superion device. In a subgroup of 98 subjects, we determined opioid-medication prevalence among subjects with a history of opioid use.ResultsAt baseline, almost 50% (94 of 190) of subjects were using opioid medication. Thereafter, there was a sharp decrease in opioid-medication prevalence from 25.2% (41 of 163) at 12 months to 13.3% (20 of 150) at 24 months to 7.5% (8 of 107) at 60 months. Between baseline and 5 years, there was an 85% decrease in the proportion of subjects using opioids. A similar pattern was also observed among subjects with a history of opiates prior to entering the trial.ConclusionStand-alone IPD is associated with a marked decrease in the need for opioid medications to manage symptoms related to LSS. In light of the current opiate epidemic, such alternatives as IPD may provide effective pain relief in patients with LSS without the need for opioid therapy.

RADIOFREQUENCY FACILITATED MANUAL SEMI-ENDOSCOPIC DISCECTOMY UTILIZING THE DISC FX® SYSTEM IN THE TREATMENT OF DISC-PREDOMINATE LUMBAR SPINAL STENOSIS

Background: Lumbar spinal stenosis (LSS) occurs with increasing prevalence in the elderly population. The American Academy of Orthopedic Surgeons has estimated that by 2021, 2.4 million adults in the United States (8-11% of the population) will be affected by this condition. Surgical options for LSS are being performed with increased frequency, high cost, and substantial risk of life-threatening complications. While nonsurgical treatment options for LSS are available, they are limited by patient selection (ligamentum flavum hypertrophy) or high rates of reoperation (Interspinous process spacer devices). This study is the first to suggest a minimally invasive treatment option for disc-predominate lumbar central canal stenosis. Objectives: To evaluate the clinical efficacy of radiofrequency facilitated manual semi-endoscopic discectomy utilizing the Disc FX® system in the treatment of disc-predominate lumbar spinal stenosis. Study Design: Single center, prospective, observational study. Setting: Multi-specialty private practice clinic. The Medical Group of South Florida, Jupiter, FL. Methods: This study involved 6 patients with disc-predominant lumbar central spinal stenosis. All patients were treated with the Disc FX® system. Radiographic evidence of central lumbar stenosis was confirmed by measurement of minimum AP canal diameter (mm) performed by 1 board-certified neuroradiologist. Inclusion criteria included absence of lumbar surgery, physical therapy within the previous 6 months, failure of epidural steroid injections (3) within the previous 8 months, spondylolisthesis limited to Grade I, disc height &gt; 50%, presence of low back axial pain + leg pain exacerbated by walking, and relieved with sitting or forward flexion, absence of dermatomal radicular leg pain, radiographic evidence of disc displacement &gt; 4 mm from disc endplate. Zurich claudication (symptom severity and physical function scale was administered 1 week preoperatively, and again 6 months postoperatively. There were no patients lost to follow up. Results: All patients in the study demonstrated moderate-severe or severe central canal stenosis, with an average AP canal diameter of 6.63 mm for all treated disc levels and 5.5 mm for the most severe levels. There was a mean improvement of 57% in a symptom severity scale and 56% in the physical function scale at 6 months. This exceeds the improvement reported with interspinous spacer devices. Limitations: Limitations include very small sample size, observational design, non-randomization, absence of share controls, short follow-up period. Conclusion: For patients suffering from discpredominant lumbar spinal stenosis, The Disc FX® System provides an effective, low-cost alternative to surgical intervention. Key words: Spinal, stenosis, claudication, disc, Disc FX®, operative, minimally invasive, Zürich claudication score

Interspinous process devices for treatment of degenerative lumbar spine stenosis: A systematic review and meta-analysis.

BackgroundDegenerative lumbar spinal stenosis is a condition related to aging in which structural changes cause narrowing of the central canal and intervertebral foramen. It is currently the leading cause for spinal surgery in patients over 65 years. Interspinous process devices (IPDs) were introduced as a less invasive surgical alternative, but questions regarding safety, efficacy, and cost-effectiveness are still unanswered.ObjectivesThe aim of this study was to provide complete and reliable information regarding benefits and harms of IPDs when compared to conservative treatment or decompression surgery and suggest directions for forthcoming RCTs.MethodsWe searched MEDLINE, EMBASE, Cochrane Library, Scopus, and LILACS for randomized and quasi-randomized trials, without language or period restrictions, comparing IPDs to conservative treatment or decompressive surgery in adults with symptomatic degenerative lumbar spine stenosis. Data extraction and analysis were conducted following the Cochrane Handbook. Primary outcomes were pain assessment, functional impairment, Zurich Claudication Questionnaire, and reoperation rates. Secondary outcomes were quality of life, complications, and cost-effectiveness. This systematic review was registered at Prospero (International prospective register of systematic reviews) under number 42015023604.ResultsThe search strategy resulted in 17 potentially eligible reports. At the end, nine reports were included and eight were excluded. Overall quality of evidence was low. One trial compared IPDs to conservative treatment: IPDs presented better pain, functional status, quality of life outcomes, and higher complication risk. Five trials compared IPDs to decompressive surgery: pain, functional status, and quality of life had similar outcomes. IPD implant presented a significantly higher risk of reoperation. We found low-quality evidence that IPDs resulted in similar outcomes when compared to standard decompression surgery. Primary and secondary outcomes were not measured in all studies and were often published in incomplete form. Subgroup analysis was not feasible. Difficulty in contacting authors may have prevented us of including data in quantitative analysis.ConclusionsPatients submitted to IPD implants had significantly higher rates of reoperation, with lower cost-effectiveness. Future trials should improve in design quality and data reporting, with longer follow-up periods.

Interspinous Process Decompression Improves Quality of Life in Patients with Lumbar Spinal Stenosis.

Lumbar spinal stenosis has been shown to negatively impact health-related quality of life. Interspinous process decompression (IPD) is a minimally invasive procedure that utilizes a stand-alone spacer to serve as a joint extension blocker to relieve neural compression in patients with spinal stenosis. Using the 5-year results from an FDA randomized controlled trial of IPD, the quality of life in 189 patients treated with the Superion® spacer was evaluated with the SF-12. Physical and mental component summary (PCS, MCS) scores were computed preoperatively and at annual intervals. For the PCS, mean scores improved from 29.4 ± 8.1 preoperatively to 41.2 ± 12.4 at 2 years (40%) and to 43.8 ± 11.6 at 5 years (49%) (p<0.001 for both comparisons). At 2 years, 81% (103 of 128) of subjects demonstrated maintenance or improvement in PCS scores. The mean MCS score improved from 50.0 ± 12.7 preoperatively to 54.4 ± 10.6 and 54.7 ± 8.6 at 2 and 5 years, respectively (p>0.10 for both comparisons). These results demonstrate that the significant impairment in physical well-being found in patients with lumbar spinal stenosis can be ameliorated, in large part, by IPD treatment.

Coflex interspinous implant placement leading to synovial cyst development: case report.

Interspinous process devices (IPDs) have been developed as less-invasive alternatives to spinal fusion with the goal of decompressing the spinal canal and preserving segmental motion. IPD implantation is proposed to treat symptoms of lumbar spinal stenosis that improve during flexion. Recent indications of IPD include lumbar facet joint syndrome, which is seen in patients with mainly low-back pain. Long-term outcomes in this subset of patients are largely unknown. The authors present a previously unreported complication of coflex (IPD) placement: the development of a large compressive lumbar synovial cyst. A 64-year-old woman underwent IPD implantation (coflex) at L4-5 at an outside hospital for low-back pain that occasionally radiates to the right leg. Postoperatively, her back and right leg pain persisted and worsened. MRI was repeated and showed a new, large synovial cyst at the previously treated level, severely compressing the patient's cauda equina. Four months later, she underwent removal of the interspinous process implant, bilateral laminectomy, facetectomy, synovial cyst resection, interbody fusion, and stabilization. At the 3-month follow-up, she reported significant back pain improvement with some residual leg pain. This case suggests that facet arthrosis may not be an appropriate indication for placement of coflex.

Percutaneous Interspinous Spacer vs Decompression in Patients with Neurogenic Claudication: An Alternative in Selected Patients?

BACKGROUNDStandalone interspinous process devices (IPDs) to treat degenerative lumbar spinal stenosis with neurogenic intermittent claudication (NIC) have shown ambiguous results in the literature.OBJECTIVETo show that a minimally invasive percutaneous IPD is safe and noninferior to standalone decompressive surgery (SDS) for patients with degenerative lumbar spinal stenosis with NIC.METHODSA multicenter, international, randomized, controlled trial (RCT) was con- ducted. One hundred sixty-three patients, enrolled at 19 sites, were randomized 1:1 to treatment with IPD or SDS and were followed for 24 mo.RESULTSThere was significant improvement in Zurich Claudication Questionnaire physical function, as mean percentage change from baseline, for both the IPD and the SDS groups at 12 mo (primary endpoint) and 24 mo (−32.3 ± 32.1, −37.5 ± 22.8; and −37.9 ± 21.7%, −35.2 ± 22.8, both P < .001). IPD treatment was not significantly noninferior (margin: 10%) to SDS treatment at 12 mo (P = .172) but was significantly noninferior at 24 mo (P = .005). Symptom severity, patient satisfaction, visual analog scale leg pain, and SF-36 improved in both groups over time. IPD showed lower mean surgical time and mean blood loss (24 ± 11 min and 6 ± 11 mL) compared to SDS (70 ± 39 min and 189 ± 148 mL, both P < .001). Reoperations at index level occurred in 18.2% of the patients in the IPD group and in 9.3% in the SDS group.CONCLUSIONConfirming 3 recent RCTs, we could show that IPD as well as open decompression achieve similar results in relieving symptoms of NIC in highly selected patients. However, despite some advantages in secondary outcomes, a higher reoperation rate for IPD is confirmed.