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.

Feasibility, safety, and efficacy of a new percutaneous interspinous device: a retrospective multicenter study.

PURPOSE: To evaluate safety and efficacy of the novel percutaneous interspinous device (PID) for the treatment of symptomatic degenerative lumbar spinal stenosis (DLSS) in 3 different centers. METHODS: From November 2016 to March 2020, 255 patients (male 125, mean age 71.2 years old range 49-91 years old) with neurogenic claudication, confirmed by electromyography, related to mono or bi-segmental lumbar central canal and/or foraminal stenosis were enrolled in the study. Magnetic resonance (MR) and/or computer tomography (CT), physical exam, and Visual Analogue Scale (VAS) and Zurich Claudication Questionnaire (ZCQ) were performed before and 6 months after the procedure. All treatments were performed under fluoroscopic guidance with local anesthesia and mild sedation. Technical success was defined as correct placement of the Lobster® (Demetrios Medical, Firenze, Italy) PID as demonstrated by computer tomography (CT) performed immediately after treatment; spinoplasty was performed in selected patients. RESULTS: PID placement was accomplished with a 99.6% success rate (257/258). The one device that was not implanted was due to a spinous process fracture. In 28 patients, more than 1 device was implanted in the same session (max 3 PIDs); 6 patients required a second implant in different session. A total of 172 prophylactic spinoplasties were performed (59.3%). No major complications occurred; 3 device misplacements were successfully treated with percutaneous retrieval and new device deployment. 99.6% of patients experienced clinical improvement. CONCLUSION: Lobster PID is an effective and safe minimally invasive decompression method for central canal and neural foraminal stenosis when patients are correctly selected.

Decompression Alone Versus Interspinous/Interlaminar Device Placement for Degenerative Lumbar Pathologies: Systematic Review and Meta-Analysis.

INTRODUCTION: Interspinous devices (ISDs) and interlaminar devices (ILDs) are marketed as alternatives to conventional surgery for degenerative lumbar conditions; comparisons with decompression alone are limited. The present study reviews the extant literature comparing the cost and effectiveness of ISDs/ILDs with decompression alone. METHODS: Articles comparing decompression alone with ISD/ILD were identified; outcomes of interest included general and disease-specific patient-reported outcomes, perioperative complications, and total treatment costs. Outcomes were analyzed at <6 weeks, 3 months, 6 months, 1 year, 2 years, and last follow-up. Analyses were performed using random effects modeling. RESULTS: Twenty-nine studies were included in the final analysis. ILD/ISD showed greater leg pain improvement at 3 months (mean difference, -1.43; 95% confidence interval, [-1.78, -1.07]; P < 0.001), 6 months (-0.89; [-1.55, -0.24]; P = 0.008), and 12 months (-0.97; [-1.25, -0.68]; P < 0.001), but not 2 years (P = 0.22) or last follow-up (P = 0.09). Back pain improvement was better after ISD/ILD only at 1 year (-0.87; [-1.62, -0.13]; P = 0.02). Short-Form 36 physical component scores or Zurich Claudication Questionnaire (ZCQ) symptom severity scores did not differ between the groups. ZCQ physical function scores improved more after decompression alone at 6 months (0.35; [0.07, 0.63]; P = 0.01) and 12 months (0.23; [0.00, 0.46]; P = 0.05). Oswestry Disability Index and EuroQoL 5 dimensions scores favored ILD/ISD at all time points except 6 months (P = 0.07). Reoperations (odds ratio, 1.75; [1.23, 2.48]; P = 0.002) and total care costs (standardized mean difference, 1.19; [0.62, 1.77]; P < 0.001) were higher in the ILD/ISD group; complications did not differ significantly between the groups (P = 0.41). CONCLUSIONS: Patient-reported outcomes are similar after decompression alone and ILD/ISD; the observed differences do not reach accepted minimum clinically important difference thresholds. ISD/ILDs have higher associated costs and reoperation rates, suggesting current evidence does not support ILD/ISDs as a cost-effective alternative to decompression alone.

Percutaneous removal and replacement of a novel percutaneous interspinous device.

Objective: The aim of this study is to explain the technique used for removing and replacing a novel percutaneous interspinous device (PID).Procedure: Three male patients, with a mean age of 66 years (range 62-72), were included in the study due to displacement (N = 2) or misplacement (N = 1) of the novel PID. This occurred after a mean of 23.3 ± 10.5 days from the initial placement (range 13-34) at the L4-L5 level (N = 1) and L3-L4 level (N = 2). Following the removal of the PID, four new devices were implanted.Conclusion: The novel PID can be safely removed either immediately after its placement during the procedure or after a certain period of days or months from its implantation. The removal procedure can be performed percutaneously under imaging guidance, by closing the four retractable wings, using the same instrumentation as utilized during the initial implantation.

Evaluating 5-year outcomes of interlaminar devices as an adjunct to decompression for symptomatic lumbar spinal stenosis.

PURPOSE: To assess and compare 5-year outcomes following uninstrumented spinal decompression and decompression with interlaminar device (ILD). To determine whether improvement in clinical outcomes correlated with changes in the radiological indices studied. This is because comparative literature between the above two procedures is limited past the 2-year timeframe. METHODS: We conducted a retrospective review of prospectively collected data from a single surgeon across 116-patients who underwent spinal decompression with or without ILD insertion between 2007 and 2015. Patients with symptomatic LSS who met the study criteria were offered spinal decompression with ILD insertion. Patients who accepted ILD were placed in the D + ILD group (n = 61); while those opting for decompression alone were placed in the DA group (n = 55). Clinical outcomes were assessed preoperatively and up to 5-years postoperatively using the ODI, Eq. 5d, VAS back and leg pain, and SF-36. Radiological indices were assessed preoperatively and up to 5-years postoperatively. RESULTS: Both groups showed statistically significant (p < 0.001) improvement in all clinical outcome indicators at all timepoints as compared to their preoperative status. The D + ILD group achieved significant improvement in radiological parameters namely foraminal height and posterior disc height in the immediate postoperative period that was maintained while the DA group did not. CONCLUSION: Our study found that in the management of LSS, clinical outcomes between those patients undergoing decompression alone compared to decompression with ILD showed statistically significant improvement in VAS back pain and radiological parameters namely foraminal height and posterior disc height at the 5-year mark. ILD does not predispose to increased reoperation rates.

Interspinous Process Devices Do Not Reduce Intervertebral Foramina and Discs Heights on Adjacent Segments.

Aim: Interspinous process device (IPD) placement is an attractive treatment option for lumbar spinal and foraminal stenosis. The goal of the treatment is to release the stress on facets joints as well as decompress the nerve roots by enlarging the intervertebral foramina and narrowed canal recesses. Purpose: To evaluate possible structural changes in the lumbar spine after implantation of an IPD on operated and adjacent segments. Patients and Methods: Twenty-two patients were enrolled in the study. Preoperative MRI scans of the lumbar spine evaluated recess and foraminal stenosis prior to the application of an IPD. CT exams were performed and morphometric measurements were made to assess the size of intervertebral foramina after implantation on the operated and adjacent segments. Results: Statistically significant enlargements in diameter and surface area of the intervertebral foramen were seen at the operating level. On the right and left sides, foraminal enlargement after the procedure was 1 mm in diameter. The average enlargement of the foramina surface area at the level of implantation was 10 mm2. The median interspinous distance was significantly enlarged by 3.5 mm. No significant changes in adjacent segments were observed. Clinical improvement was confirmed by the Oswestry Disability Index (ODI) and visual analog scale (VAS). Preoperative disability was reduced (mean ODI from 70.5 (12.25) to 49.5 (23.75)), as well as back pain (mean VAS from 8.0 (1.7) to 4.4 (2.6)) and pain in lower limbs (mean VAS from 7.4 (1.9) to 3.8 (2.9)). Conclusion: Decompression surgery using an IPD is effective in the treatment of lumbar foraminal and canal stenosis. It provides relief of symptoms in short-term observation through enlargement of intervertebral foramina and decompression of neural roots. It reduces overload of facet joints of the operated segment and does not decrease the size of the intervertebral foramina and disc heights of adjacent segments.

Analysis of Long-Term Results of Lumbar Discectomy With and Without an Interspinous Device.

BACKGROUND: Discectomy is the surgical treatment of choice for disc herniation. However, discectomy can lead to disc degeneration and vertebral instability over time. Interspinous devices (ISDs), added to conventional surgery, constitute a low-invasive alternative that attempts to prevent these complications. The aim of this study is to compare the long-term clinical and functional outcomes of patients undergoing conventional discectomy with those who had an ISD added during surgery. METHODS: This analytical-descriptive, retrospective, and transversal studyinvestigated outcomes of 114 patients who underwent surgery for a lumbar disc herniation between 2008 and 2011. The results were evaluated with a minimum follow-up of 8 years (mean, 10 years) by means of different questionnaires: visual analog scale (VAS), Oswestry Disability Index (ODI), consumption of analgesic medication, work status, degree of satisfaction, and complications and reinterventions during the follow-up period. RESULTS: At the end of the follow-up, an overall improvement of VAS of 5 points (71%) and ODI of 36 points (77%) was observed, with a degree of satisfaction of 76% with disc surgery. The analysis between both groups showed a better behavior in VAS and ODI in the implant group, with a pre- and postsurgery difference of 73% and 79% compared to 66% and 77% in the control group, respectively, though this finding was not statistically significant. The current analgesic consumption and the degree of satisfaction were also better in the group with an implant. Compared with the non-implant group, the number of reinterventions at the end of the follow-up was lower (7% vs 15.5%) and the time until the second intervention was higher (81.5 vs 41 months) in the group with an implant, but the differences were not statistically significant. CONCLUSIONS: Lumbar discectomy proved to be a safe technique for the treatment of disc herniation, and results are maintained over time. The additional gesture of adding an ISD to conventional discectomy improves clinical outcomes overall, but not in a statistically significant way. The lower number of reinterventions and the longer period without surgery being required may mean a certain protective effect of the ISD on the intervertebral disc being operated on.

Neurosurgical Management of Interspinous Device Complications: A Case Series.

Background: Best practice guidelines for treating lumbar stenosis include a multidisciplinary approach, ranging from conservative management with physical therapy, medication, and epidural steroid injections to surgical decompression with or without instrumentation. Marketed as an outpatient alternative to a traditional lumbar decompression, interspinous process devices (IPDs) have gained popularity as a minimally invasive stabilization procedure. IPDs have been embraced by non-surgical providers, including physiatrists and anesthesia interventional pain specialists. In the interest of patient safety, it is imperative to formally profile its safety and identify its role in the treatment paradigm for lumbar stenosis. Case Description: We carried out a retrospective review at our institution of neurosurgical consultations for patients with hardware complications following the interspinous device placement procedure. Eight cases within a 3-year period were identified, and patient characteristics and management are illustrated. The series describes the migration of hardware, spinous process fracture, and worsening post-procedural back pain. Conclusions: IPD placement carries procedural risk and requires a careful pre-operative evaluation of patient imaging and surgical candidacy. We recommend neurosurgical consultation and supervision for higher-risk IPD cases.

Decompression Surgery versus Interspinous Devices for Lumbar Spinal Stenosis: A Systematic Review of the Literature.

In this retrospective review study, the authors systematically reviewed the literature to elucidate the efficacy and complications associated with decompression and interspinous devices (ISDs) used in surgeries for lumbar spinal stenosis (LSS). LSS is a debilitating condition that affects the lumbar spinal cord and spinal nerve roots. However, a comprehensive report on the relative efficacy and complication rate of ISDs as they compare to traditional decompression procedures is currently lacking. The PubMed database was queried to identify clinical studies that exclusively investigated decompression, those that exclusively investigated ISDs, and those that compared decompression with ISDs. Only prospective cohort studies, case series, and randomized controlled trials that evaluated outcomes using the Visual Analog Scale (VAS), Oswestry Disability Index, or Japanese Orthopedic Association scores were included. A random-effects model was established to assess the difference between preoperative and the 1-2-year postoperative VAS scores between ISD surgery and lumbar decompression. This study included 40 papers that matched our criteria. Twenty-five decompression-exclusive clinical trials with 3,386 patients and a mean age of 68.7 years (range, 31-88 years) reported a 2.2% incidence rate of dural tears and a 2.6% incidence rate of postoperative infections. Eight ISD-exclusive clinical trials with 1,496 patients and a mean age of 65.1 (range, 19-89 years) reported a 5.3% incidence rate of postoperative leg pain and a 3.7% incidence rate of spinous process fractures. Seven studies that compared ISDs and decompression in 624 patients found a reoperation rate of 8.3% in ISD patients vs. 3.9% in decompression patients; they also reported dural tears in 0.32% of ISD patients vs. 5.2% in decompression patients. A meta-analysis of the randomized controlled trials found that the differences in preoperative and postoperative VAS scores between the two groups were not significant. Both decompression and ISD interventions are unique surgical interventions with different therapeutic efficacies and complications. The collected studies do not consistently demonstrate superiority of either procedure over the other but understanding the differences between the two techniques can help tailor treatment regimens for patients with LSS.

Functional and radiographic evaluation of an interspinous device as an adjunct for lumbar interbody fusion procedures.

In the last decades, several interspinous process devices were designed as a minimally invasive treatment option for spinal stenosis. In order to minimise surgical trauma, interspinous process devices were recently discussed as an alternative posterior fixation in vertebral interbody fusions. Therefore, the purpose of this study was to evaluate the effect of a newly designed interspinous device with polyester bands (PBs) on range of motion (RoM) and centre of rotation (CoR) of a treated motion segment in comparison with an established interspinous device with spikes (SC) as well as with pedicle screw instrumentation in lumbar fusion procedures. Flexibility tests with an applied pure moment load of 7.5 Nm were performed in six monosegmental thoracolumbar functional spinal units (FSUs) in the following states: (a) native, (b) native with PB device, (c) intervertebral cage with PB device, (d) cage with SC and (e) cage with internal fixator. The resulting RoM was normalised to the native RoM. The CoR was determined of X-ray images taken in maximal flexion and extension during testing. In flexion and extension, the PB device without and with the cage reduced the RoM of the native state to 58% [standard deviation (SD) 17.8] and 53% (SD 15.7), respectively. The SC device further reduced the RoM to 27% (SD 16.8), while the pedicle screw instrumentation had the most reducing effect to 17% (SD 17.2) (p < 0.01). In lateral bending and axial rotation, the interspinous devices had the least effect on the RoM. Compared to the native state, for all instrumentations the CoR showed a small shift towards cranial. In the anterior-posterior direction, the SC device and the pedicle screw instrumentation shifted the CoR towards the posterior wall. The interspinous devices significantly reduced the RoM in flexion/extension, while in axial rotation and lateral bending only the internal fixator had a significant effect on the RoM.

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.

Biomechanical analysis of a new lumbar interspinous device with optimized topology.

Interspinous spacers used stand-alone preserve joint movement but provide little protection for diseased segments of the spine. Used as adjuncts with fusion, interspinous spacers offer rigid stability but may accelerate degeneration on adjacent levels. Our new device is intended to balance the stability and preserves motion provided by the implant. A new interspinous spacer was devised according to the results of topology optimization studies. Four finite element (FE) spine models were created that consisted of an intact spine without an implant, implantation of the novel, the device for intervertebral assisted motion (DIAM system), and the Dynesys system. All models were loaded with moments, and their range of motions (ROMs), peak disc stresses, and facet contact forces were analyzed. The limited motion segment ROMs, shielded disc stresses, and unloaded facet contact forces of the new devices were greater than those of the DIAM and Dynesys system at L3-L4 in almost all directions of movements. The ROMs, disc stresses, and facet contact forces of the new devices at L2-L3 were slightly greater than those in the DIAM system, but much lower than those in the Dynesys system in most directions. This study demonstrated that the new device provided more stability at the instrumented level than the DIAM system did, especially in lateral rotation and the bending direction. The device caused fewer adjacent ROMs, lower disc stresses, and lower facet contact forces than the Dynesys system did. Additionally, this study conducted topology optimization to design the new device and created a smaller implant for minimal invasive surgery.

Biomechanical effects of hybrid stabilization on the risk of proximal adjacent-segment degeneration following lumbar spinal fusion using an interspinous device or a pedicle screw-based dynamic fixator.

OBJECTIVE Pedicle screw-rod-based hybrid stabilization (PH) and interspinous device-based hybrid stabilization (IH) have been proposed to prevent adjacent-segment degeneration (ASD) and their effectiveness has been reported. However, a comparative study based on sound biomechanical proof has not yet been reported. The aim of this study was to compare the biomechanical effects of IH and PH on the transition and adjacent segments. METHODS A validated finite element model of the normal lumbosacral spine was used. Based on the normal model, a rigid fusion model was immobilized at the L4-5 level by a rigid fixator. The DIAM or NFlex model was added on the L3-4 segment of the fusion model to construct the IH and PH models, respectively. The developed models simulated 4 different loading directions using the hybrid loading protocol. RESULTS Compared with the intact case, fusion on L4-5 produced 18.8%, 9.3%, 11.7%, and 13.7% increments in motion at L3-4 under flexion, extension, lateral bending, and axial rotation, respectively. Additional instrumentation at L3-4 (transition segment) in hybrid models reduced motion changes at this level. The IH model showed 8.4%, -33.9%, 6.9%, and 2.0% change in motion at the segment, whereas the PH model showed -30.4%, -26.7%, -23.0%, and 12.9%. At L2-3 (adjacent segment), the PH model showed 14.3%, 3.4%, 15.0%, and 0.8% of motion increment compared with the motion in the IH model. Both hybrid models showed decreased intradiscal pressure (IDP) at the transition segment compared with the fusion model, but the pressure at L2-3 (adjacent segment) increased in all loading directions except under extension. CONCLUSIONS Both IH and PH models limited excessive motion and IDP at the transition segment compared with the fusion model. At the segment adjacent to the transition level, PH induced higher stress than IH model. Such differences may eventually influence the likelihood of ASD.

Interspinous implants: are the new implants better than the last generation? A review.

PURPOSE OF REVIEW: Interspinous process devices (IPDs) are used in the surgical treatment of lumbar spinal stenosis. The purpose of this review is to compare the first generation with the next-generation devices in terms of complications, device failure, reoperation rates, symptom relief, and outcome. RECENT FINDINGS: Thirty-seven studies were included from 2011 to 2016. Device failure occurred at a mean of 3.7%, with a lower tendency to happen with next-generation IPDs. Reoperations occurred at a lower rate with the next-generation devices, with a mean follow up of 24 months (3.7% vs. 11.1%). The clinical outcome is not influenced by the type of IPD. The long-term functionality of these devices is questionable, with radiologic changes and recurrence of symptoms often seen by 2 years following implantation. Next-generation devices do not appear to be subject to the same "bounce back" effect of symptom re-emergence after several years.

Biomechanical Comparison of Spinal Fusion Methods Using Interspinous Process Compressor and Pedicle Screw Fixation System Based on Finite Element Method.

OBJECTIVE: To investigate the biomechanical effects of a newly proposed Interspinous Process Compressor (IPC) and compare with pedicle screw fixation at surgical and adjacent levels of lumbar spine. METHODS: A three dimensional finite element model of intact lumbar spine was constructed and two spinal fusion models using pedicle screw fixation system and a new type of interspinous devices, IPC, were developed. The biomechanical effects such as range of motion (ROM) and facet contact force were analyzed at surgical level (L3/4) and adjacent levels (L2/3, L4/5). In addition, the stress in adjacent intervertebral discs (D2, D4) was investigated. RESULTS: The entire results show biomechanical parameters such as ROM, facet contact force, and stress in adjacent intervertebral discs were similar between PLIF and IPC models in all motions based on the assumption that the implants were perfectly fused with the spine. CONCLUSION: The newly proposed fusion device, IPC, had similar fusion effect at surgical level, and biomechanical effects at adjacent levels were also similar with those of pedicle screw fixation system. However, for clinical applications, real fusion effect between spinous process and hooks, duration of fusion, and influence on spinous process need to be investigated through clinical study.

Degenerative lumbar spinal stenosis treatment with Aperius™ PerCLID™ system and Falena® interspinous spacers: 1-year follow-up of clinical outcome and quality of life.

PURPOSE: Evaluation of the efficacy of the Falena(®) and Aperius™ PerCLID™ interspinous devices in the treatment of degenerative lumbar spinal stenosis with neurogenic intermittent claudication refractory to conservative treatment. MATERIALS AND METHODS: We retrospectively analyzed data from 24 patients (20 male and 4 female patients; 61 ± 7 years old), treated with an implantation of the AperiusTM PerCLID™ system, and from 35 patients (29 male and 6 female patients; 65 ± 9 years old) treated with the Falena(®) interspinous device.Patient pain intensity was evaluated by a 10-point visual analog scale (VAS), with a score (ranging from 0 = no pain to 10 = unbearable pain) that was collected before the procedure, at baseline; and at months 1, 6 and 12 after the interventional procedure. The assessment of quality of life (QOL) impairment was evaluated by the Oswestry Disability Index (ODI) questionnaire, which was administered beforehand at baseline; and at months 1, 6 and 12 after the interventional procedure. The vertebral canal area was measured by magnetic resonance imaging (MRI) scans before the treatment and at the one-year follow-up. RESULTS: All patients completed the study with no complications. Both the Falena group and Aperius group of surgery patients showed a statistically significant reduction of their VAS and ODI scores at the 6- and 12-month follow-up (p < 0.0001). A statistically significant increase in the vertebral canal area was observed both in the group that received Falena (p < 0.0001) and in the group that received Aperius (p = 0.0003). At the 1-year follow-up, we observed that there was a higher increase of vertebral canal area in those patients whom were treated with the Falena device (p < 0.001). CONCLUSIONS: The implantation of Falena(®) and Aperius™ PerCLID™ interspinous devices is an effective and safe procedure, in the medium term.

Biomechanical Comparison of Spinal Fusion Methods Using Interspinous Process Compressor and Pedicle Screw Fixation System Based on Finite Element Method

OBJECTIVE: To investigate the biomechanical effects of a newly proposed Interspinous Process Compressor (IPC) and compare with pedicle screw fixation at surgical and adjacent levels of lumbar spine. METHODS: A three dimensional finite element model of intact lumbar spine was constructed and two spinal fusion models using pedicle screw fixation system and a new type of interspinous devices, IPC, were developed. The biomechanical effects such as range of motion (ROM) and facet contact force were analyzed at surgical level (L3/4) and adjacent levels (L2/3, L4/5). In addition, the stress in adjacent intervertebral discs (D2, D4) was investigated. RESULTS: The entire results show biomechanical parameters such as ROM, facet contact force, and stress in adjacent intervertebral discs were similar between PLIF and IPC models in all motions based on the assumption that the implants were perfectly fused with the spine. CONCLUSION: The newly proposed fusion device, IPC, had similar fusion effect at surgical level, and biomechanical effects at adjacent levels were also similar with those of pedicle screw fixation system. However, for clinical applications, real fusion effect between spinous process and hooks, duration of fusion, and influence on spinous process need to be investigated through clinical study.

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.

Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study.

OBJECT The authors evaluated the biomechanical effects of an interspinous process (ISP) device on kinematics and load sharing at the implanted and adjacent segments. METHODS A 3D finite-element (FE) model of the lumbar spine (L1-5) was developed and validated through comparison with published in vitro study data. Specifically, validation was achieved by a flexible (load-control) approach in 3 main planes under a pure moment of 10 Nm and a compressive follower load of 400 N. The ISP device was inserted between the L-3 and L-4 processes. Intact and implanted cases were simulated using the hybrid protocol in all motion directions. The resultant motion, facet load, and intradiscal pressure after implantation were investigated at the index and adjacent levels. In addition, stress at the bone-implant interface was predicted. RESULTS The hybrid approach, shown to be appropriate for adjacent-level investigations, predicted that the ISP device would decrease the range of motion, facet load, and intradiscal pressure at the index level relative to the corresponding values for the intact spine in extension. Specifically, the intradiscal pressure induced after implantation at adjacent segments increased by 39.7% and by 6.6% at L2-3 and L4-5, respectively. Similarly, facet loads at adjacent segments after implantation increased up to 60% relative to the loads in the intact case. Further, the stress at the bone-implant interface increased significantly. The influence of the ISP device on load sharing parameters in motion directions other than extension was negligible. CONCLUSIONS Although ISP devices apply a distraction force on the processes and prevent further extension of the index segment, their implantation may cause changes in biomechanical parameters such as facet load, intradiscal pressure, and range of motion at adjacent levels in extension.

Interspinous spacer decompression (X-STOP) for lumbar spinal stenosis and degenerative disk disease: a multicenter study with a minimum 3-year follow-up.

Interspinous distraction devices provide an effective treatment for patients suffering from lumbar spinal stenosis and/or degenerative disk disease. The aim of this multicenter study was the prospective evaluation of patients treated for symptomatic lumbar spinal stenosis with interspinous process decompression (IPD) implants compared with a population of patients managed with conservative treatment. 542 patients affected by symptomatic lumbar spine degenerative disease were enrolled in a controlled trial. 422 patients underwent surgical treatment consisting of X-STOP device implantation, whereas 120 control cases were managed conservatively. Both patient groups underwent follow-up evaluations at 6, 12, 24, and 36 months using the Zurich Claudication Questionnaire, the Visual Analog Scale score and spinal lumbar X-rays, CT scans and MR imaging. One-year follow-up evaluation revealed positive good results in the 83.5% of patients treated with IPD with respect to 50% of the nonoperative group cases. During the first three years, in 38 out of the 120 control cases, a posterior decompression and/or spinal fixation was performed because of unsatisfactory results of the conservative therapy. In 24 of 422 patients, the IPD device had to be removed, and a decompression and/or pedicle screw fixation was performed because of the worsening of neurological symptoms. Our results support the effectiveness of surgery in patients with stenosis. IPD may offer an effective and less invasive alternative to classical microsurgical posterior decompression in selected patients with spinal stenosis and lumbar degenerative disk diseases.