Multilevel Instrumentation Research Articles

Projections of Single-level and Multilevel Spinal Instrumentation Procedure Volume and Associated Costs for Medicare Patients to 2050.

Instrumented spinal fusions can be used in the treatment of vertebral fractures, spinal instability, and scoliosis or kyphosis. Construct-level selection has notable implications on postoperative recovery, alignment, and mobility. This study sought to project future trends in the implementation rates and associated costs of single-level versus multilevel instrumentation procedures in US Medicare patients aged older than 65 years in the United States. Data were acquired from the Centers for Medicare & Medicaid Services from January 1, 2000, to December 31, 2019. Procedure costs and counts were abstracted using Current Procedural Terminology codes to identify spinal level involvement. The Prophet machine learning algorithm was used, using a Bayesian Inference framework, to generate point forecasts for 2020 to 2050 and 95% forecast intervals (FIs). Sensitivity analyses were done by comparing projections from linear, log-linear, Poisson and negative-binomial, and autoregressive integrated moving average models. Costs were adjusted for inflation using the 2019 US Bureau of Labor Statistics' Consumer Price Index. Between 2000 and 2019, the annual spinal instrumentation volume increased by 776% (from 7,342 to 64,350 cases) for single level, by 329% (from 20,319 to 87,253 cases) for two-four levels, by 1049% (from 1,218 to 14,000 cases) for five-seven levels, and by 739% (from 193 to 1,620 cases) for eight-twelve levels (P < 0.0001). The inflation-adjusted reimbursement for single-level instrumentation procedures decreased 45.6% from $1,148.15 to $788.62 between 2000 and 2019, which is markedly lower than for other prevalent orthopaedic procedures: total shoulder arthroplasty (-23.1%), total hip arthroplasty (-39.2%), and total knee arthroplasty (-42.4%). By 2050, the number of single-level spinal instrumentation procedures performed yearly is projected to be 124,061 (95% FI, 87,027 to 142,907), with associated costs of $93,900,672 (95% FI, $80,281,788 to $108,220,932). The number of single-level instrumentation procedures is projected to double by 2050, while the number of two-four level procedures will double by 2040. These projections offer a measurable basis for resource allocation and procedural distribution.

Circumferential approach via dynamic position in OLIF combined with freehand screw pedicle fixation for lumbar tuberculosis requiring multilevel instrumentation: a 3-year retrospective study

PurposeTo advance a modified oblique lumbar interbody fusion (M-OLIF) achieving anterior debridement and posterior freehand instrumentation simultaneously in circumferential approach via dynamic position and compare with traditional combined anterior–posterior surgery (CAPS) in clinical and radiological evaluation.Patients and methodsInnovative freehand instrumentation in floating position was described. Consecutive patients having undergone surgeries for lumbar tuberculosis from 2017 January to 2019 December had been retrospectively reviewed. Patients with follow-ups for at least 36 months were included and divided into M-OLIF or CAPS group according to surgical methods applied. Outcomes included operation time, estimated blood loss, complication profile for safety evaluation; Vascular Analogue Scale (VAS) and Oswestry Disability Index (ODI) for efficacy evaluation; C-reactive protein and Erythrocyte Sedimentation Rate for tuberculosis activity and recurrence evaluation; X-ray and CT scan for radiological evaluation.ResultsTotally 56 patients had been enrolled in the study (26 for M-OLIF and 30 for CAPS). Compared with CAPS group, M-OLIF group illustrated significantly decreased estimated blood loss, operation time, hospital stay, and less postoperative morbidities. Meanwhile, M-OLIF group showed earlier improvement in VAS in 3 days and ODI in the first month postoperatively, without obvious discrepancy in further follow-ups. The overall screw accuracy in M-OLIF and CAPS group was 93.8% and 92.3% respectively, without significant difference in perforation distribution. ConclusionM-OLIF was efficient for lumbar tuberculosis requiring multilevel fixation, with reduced operation time and iatrogenic trauma, earlier clinical improvement compared with traditional combined surgery.

Flexion/Extension Cervical Magnetic Resonance Imaging: A Potentially Useful Tool for Decision-Making in Patients with Symptomatic Degenerative Cervical Spine

To evaluate the reliability and usefulness of cervical flexion/extension magnetic resonance imaging (MRI) as a tool for decision-making regarding treatment of symptomatic cervical spondylosis. We prospectively collected demographic, clinical, and flexion/neutral/extension MRI data for consecutive 24 patients who had presented with symptomatic cervical degenerative disease. From the survey responses, we analyzed the agreement between clinical interpretation and judgment when neutral MRI (nMRI) versus flexion/extension MRI (fMRI/eMRI) had been provided. Additionally, the mean cervical canal diameter (MCCD), as measured by 2 independent radiologists, was tested for intra- and interobserver reliability. The differences in MCCD between nMRI, fMRI, and eMRI and the correlation with the qualitative assessment by spine surgeons were also evaluated. Using nMRI only, 16.7%-33.3% of the surgical candidates were missed. Neurosurgeons were significantly more likely to use a posterior approach and instrumentation when fMRI/eMRI studies were available compared with nMRI studies alone. More levels had undergone surgery when the providers had been presented with the fMRI/eMRI studies. The raters expressed a preference for the use of fMRI/eMRI in their future practice. The MCCD was significantly different when measured on the nMRI studies compared with the fMRI/eMRI studies and correlated with the qualitative assessments. Flexion/extension MRI studies were useful for assessing patients with cervical degenerative spine disorders regarding the surgical indication, direction of the approach, and use of multilevel instrumentation, especially for patients with early cervical myelopathy.

Multi-level instrumentation of bivouac thermoregulation: current methods and future directions

Multi-level instrumentation of bivouac thermoregulation: current methods and future directions

A case report of robotic-guided prone transpsoas lumbar fusion in a patient with lumbar pseudarthrosis, adjacent segment disease, and degenerative scoliosis.

BackgroundSurgical treatment of scoliosis includes long and invasive multi-level instrumentation and correction which may result in high rates of postoperative complications, especially in elderly patients with osteopenia or multiple comorbidities. Minimally invasive surgical options may benefit these patients.Case descriptionA 73-year-old female patient with a history of degenerative lumbar scoliosis, L4–5 pseudarthrosis, and resulting L5-S1 adjacent segment following prior unsuccessful lateral L4–5 interbody fusion presented to the clinic with severe lower back pain and lower extremity radiculopathy. The decision was made to proceed with surgical correction via a robotic-guided prone transpsoas (PTP) approach, which is a novel approach similar to lateral lumbar interbody fusion (LLIF) with the patient in a prone decubitus position. Excellent spinal alignment was achieved with no complications. On two-month follow-up, imaging revealed pedicle screws at the L3, L4, L5 levels and at the sacrum without change and continued interbody cages position with no signs or symptoms of infection.DiscussionMinimally invasive procedures have demonstrated benefit in spine surgery especially for at risk populations. The LLIF procedure has been well established for use in a wide range of spinal pathologies given its noted benefits in increasing spinal column stability through posterior fixation and indirect decompression. However, only marginal improvements in segmental lordosis are expected and there are reports of neurological complications. The PTP procedure has emerged as an alternative to LLIF for the treatment of spinopelvic pathologies. This approach enables greater improvements to spinal lordosis through single-position surgery while simultaneously reducing intraoperative repositioning and providing the known benefits of lateral interbody surgery.ConclusionOur experience suggests that the PTP approach is safe and effective because it does not require patient repositioning, easily interfaces with robotic guidance, and achieves increased lordosis gains via the prone positional effect compared to LLIF and comparable approaches.

Routine In-Hospital Radiographs Following Anterior Cervical Discectomy and Fusion Surgery: Neither Necessary nor Cost-Effective?

BackgroundDespite a paucity of evidence or literature to support routine in-hospital post-operative radiographs (POXR) of anterior cervical discectomy and fusion (ACDF) surgery, it remains accepted practice. Most spinal surgeons consider it part of their standard post-operative routine for ACDF despite nearly always documenting a ’satisfactory intra-operative image’ at the end of the operation. With an increasing financial pressure on NHS resources, our investigations should be clinically justified and evidence-based.PurposeTo evaluate whether a post-operative radiograph of the cervical spine before discharge is either clinically justified or cost-effective in patients who have undergone an ACDF, despite having satisfactory intra-operative imaging.DesignA retrospective review of 101 consecutive ACDF patients of radiographs performed before discharge, associated length of inpatient stay, and any complications involved.MethodsA retrospective review was performed of 101 ACDF patients who had single or multi-level instrumentation for degenerative spinal disease from a single neurosurgical centre from all surgeons. Seventy-eight had an in-hospital post-operative anteroposterior (AP) and lateral radiograph, 23 did not. In 95 of these, it was documented that there was ‘satisfactory intra-operative imaging’ before the closure of skin, six lacked documentation of this. All patients had intra-operative imaging of completed instrumentation on the radiology system. Any post-operative complications were noted, and the length of hospital stay (LOS) was recorded. Six patients underwent ACDF following trauma, therefore leaving 95 elective cases. Study parameters also included: number of levels operated on, whether or not a plate was used with a cage, hospital costings for 2-view imaging and additional days of inpatient stay. ResultsThere was one out of our 101 patients where the post-operative radiograph confirmed unsatisfactory placement of metalwork and warranted a return to surgery. However, the decision to perform this x-ray was based purely on the deteriorating post-operative clinical picture. In the cohort that had POXR’s, the average length of stay was 66.7 hours. Without POXR, it was 21 hours. The additional cost to the trust of performing the in-hospital radiographs was calculated to be £71,523 per year.ConclusionIn patients who undergo ACDF surgery with an uneventful post-operative course and have satisfactory intra-operative imaging, in-hospital post-operative radiographs serve no clinical purpose and delay discharge. This gives additional cost to the trust, unnecessary radiation exposure and occupies potential bedspace.

Legal custom as a multilevel instrument of legal regulation of labor in the Russian Federation and the EU

The article examines some of the issues of recognizing legal custom as a source of labor law from the point of view of the current Russian legal regulation, foreign experience and at the EU level. The practice of jurisdictional bodies in the application of legal customs as sources of labor law in the resolution of labor disputes is taken into account and evaluated. The author proposes the qualification of legal custom in the field of labor law through a set of features. The article also considers for the first time the phenomenon of legal custom as a source of labor law at the supranational level (EU level).

The Impact of Corrective Surgery on Health-Related Quality of Life Subclasses in Adult Scoliosis: Will Degree of Correction Prognosticate Degree of Improvement?

Objectives in scoliosis corrective surgery include restoration of normal sagittal and coronal parameters to achieve patient satisfaction. HRQLs improvements remain limited after corrective surgery.The aim of this study was to evaluate the HRQL subclass variability specific to the sagittal and coronal correction in adult scoliosis surgery. This multi-centre prospective analysis of consecutive adult spinal deformity (ASD) patients, from five European centres, only included multilevel instrumentation for scoliosis. d-(delta) values for each parameter represented pre to post-operative changes. Parameters included demographics, baseline, 1- and 2-year. HRQL outcomes (Oswestry disability index (ODI), Scoliosis Research Society (SRS)-22 and Short Form (SF36)), sagittal correction including relative spinopelvic alignment (dRSA) and coronal correction including major Cobb (dCobb) angles. A total of 353 patients reached 1-year and 2-year follow up. All HRQL total scores significantly improved postoperatively, including ODI, SRS-22 and SF36. HRQL subclasses which displayed persistent improvements correlated to dRSA included sex-life, self-image, fatigue, vitality, social functioning. The only HRQL subclass improvement that correlated with dCobb was self-image. Adult scoliosis surgery improves overall HRQL, having a minimal effect on each variable. Importantly, greater coronal deformity correction affects only greater self-image scores, whereas with greater sagittal correction there are many greater HRQL sub-class impacts. Correction and restoration of coronal balance is one of the surgical goals in adult scoliosis but the degree to which Cobb angle is corrected, apart from self-image, does not correlate with gains in sub-classes of HRQL. These results need to be taken into account when planning surgery.

Minimally Invasive Techniques for Iliac Bolt Placement: 2-Dimensional Operative Video.

As the popularity of minimally invasive surgery (MIS) continues to grow, novel techniques are needed to meet the demands of multisegment fixation for advanced spinal diseases. In one such example, iliac bolts are often required to anchor large fusion constructs, but MIS technical notes are missing from the literature. A 67-yr-old female presented with a symptomatic coronal deformity: preoperative pelvic incidence=47°, pelvic tilt=19°, and lumbar lordosis=29°, sagittal vertical axis = +5.4 cm with 30° of scoliosis. The operative plan included T10-ilium fusion with transforaminal interbody grafts at L2-3, L3-4, L4-5, and L5-S1. The intraoperative video is of minimally invasive placement of iliac bolts using the O-Arm Surgical Imaging System (Medtronic®). The patient consented to the procedure. A mini-open exposure that remains above the fascial planes allows for multilevel instrumentation with appropriate decompression at the interbody segments. After the placement of the pedicle screws under image-guidance, the direction is turned to the minimally invasive iliac bolts. Following the trajectory described in the standard open approach,1 the posterior superior iliac spine (PSIS) is identified with the navigation probe, which will guide the Bovie cautery through the fascia. This opening assists in the trajectory of the navigated-awl tap toward the anterior superior iliac spine (ASIS). Next, 8.5mm x 90mm iliac screws were placed in the cannulated bone under navigation. After intraoperative image confirmation of screw placement, the contoured rods are threaded under the fascia. The setscrews lock the rod in position. MIS approaches obviate cross-linking the rods, rendering pelvic fixation more facile. This technique allows for minimal dissection of the posterior pelvic soft tissue while maintaining adequate fixation.

A Novel Plate-Based System (UNIMAX) for Posterior Instrumented Spinal Fusion.

IntroductionThe polyaxial head pedicle screw-rod system is a commonly used spinal instrumentation technique to achieve stabilization, deformity correction, and bony fusion. We present a novel plate-based pedicle screw system (UNIMAXTM) that can be used for multi-level instrumentation with potential advantages for selected applications.MethodsBilateral titanium monoaxial pedicle screws are linked at each level by robust transversely oriented cross plates forming ring constructs capable of rigid triangulation at each level. The cross plates are then interconnected by sagittally oriented rigid plates situated medial to the screw heads. Biomechanically, the construct was tested for quasi-static torsion and fatigue in axial compression. The system is approved by the Food and Drug Administration (FDA). The system and case examples are presented showing its potential advantages.ResultsThe quasi-static torsion, the mean for the angular displacement, torsional stiffness, and torsional ultimate strength was 2.5 degrees (SD ± 0.8), 5.3 N-m/mm (SD ± 0.7), and 21.6 N-m (SD ± 4.4). For the fatigue in axial compression, the closed ring construct failed when the applied load and bending moment were ≥ 1500 N and ≥ 60 N.m. This system maximizes the construct rigidity, allows easy extension to adjacent levels, and can be incorporated intuitively into practice. The ring construct with triangulation at each level, together with its biomechanical robustness, predicts a high pullout resistance. It requires an open posterior approach incompatible with minimally invasive techniques.ConclusionThis system may have advantages over the screw-rod systems in carefully selected situations requiring extra rigidity and high pull-out strength for complex reconstructions, sagittal and/or coronal correction, patients with poor bone quality, revisions, and/or extension to adjacent levels.

Liberalism Versus Communitarianism in Cultural Heritage Law

The aim of this study is to investigate the important role of liberal-communitarian debate in cultural heritage law and politics. Derek Gillman in the book titled “The Idea of Cultural Heritage” stressed that “During recent decades, two parallel debates have occurred with respect to public policy and heritage”, and mentioned above is the second one, which “takes place between political philosophers, especially liberal and communitarian thinkers of various shades.” The following study brings attention to the external perspective. That is, these philosophical concepts which appeared beyond legal sciences, but they have the impact on both law and almost all aspects of social life. Liberalism and communitarianism, despite their differences, are particularly useful lens through which to consider law and its functions within contemporary society. Therefore, this begs the question as to what is their approach to the cultural heritage law and practice. While much has been written about liberalism and communitarianism, their impact on cultural heritage still remains shrouded in mystery. We do accept and stress that cultural heritage law is nowadays recognised as the multilevel legal instruments for safeguarding, protection, preservation and maintenance of cultural heritage, cultural property, or even cultural rights. It is not only “multilevel”, but also “multivalued”, and for that reason many theoretical and practical problems are noticed. Liberalism versus communitarianism is one of the most significant debate. As a result, the main aim of this article is to outline the influence of liberalism and communitarianism on cultural heritage law.

Complex wound closure by plastic surgery following resection of spinal neoplasms minimizes postoperative wound complications in high-risk patients.

Wound breakdown and infection are common postoperative complications following resection of spinal neoplasms. Accordingly, it has become common practice at some centers for plastic surgeons to assist with closure of large posterior defects after spine tumor resection. In this study, the authors tested the hypothesis that plastic surgery closure of complex spinal defects improves wound outcomes following resection of spinal neoplastic disease. Electronic medical records of consecutive patients who underwent resection of a spinal neoplasm between June 2015 and January 2019 were retrospectively reviewed. Patients were separated into two subpopulations based on whether the surgical wound was closed by plastic surgery or neurosurgery. Patient demographics, preoperative risk factors, surgical details, and postoperative outcomes were collected in a central database and summarized using descriptive statistics. Outcomes of interest included rates of wound complication, reoperation, and mortality. Known preoperative risk factors for wound complication in spinal oncology were identified based on literature review and grouped categorically. The presence of each category of risk factors was then compared between groups. Univariate and multivariate linear regressions were applied to define associations between individual risk factors and wound complications. One hundred six patients met inclusion criteria, including 60 wounds primarily closed by plastic surgery and 46 by neurosurgery. The plastic surgery population included more patients with systemic metastases (58% vs 37%, p = 0.029), prior radiation (53% vs 17%, p < 0.001), prior chemotherapy (37% vs 15%, p = 0.014), and sacral region tumors (25% vs 7%, p = 0.012), and more patients who underwent procedures requiring larger incisions (7.2 ± 3.6 vs 4.5 ± 2.6 levels, p < 0.001), prolonged operative time (413 ± 161 vs 301 ± 181 minutes, p = 0.001), and greater blood loss (906 ± 1106 vs 283 ± 373 ml, p < 0.001). The average number of risk factor categories present was significantly greater in the plastic surgery group (2.57 vs 1.74, p < 0.001). Despite the higher relative risk, the plastic surgery group did not experience a significantly higher rate of wound complication (28% vs 17%, p = 0.145), reoperation (17% vs 9%, p = 0.234), or all-cause mortality (30% vs 13%, p = 0.076). One patient died from wound-related complications in each group (p = 0.851). Regression analyses identified diabetes, multilevel instrumentation, and BMI as the factors associated with the greatest wound complications. Involving plastic surgery in the closure of spinal wounds after resection of neoplasms may ameliorate expected increases in wound complications among higher-risk patients.

Mini Screws for Improving Accuracy in Navigation-assisted Spine Surgery.

Presentation of a surgical technique with accompanying video (Supplemental Digital Content 1, http://links.lww.com/CLINSPINE/A67) of an illustrative case. The objective of this study was to present a helpful and easy-to-implement technique for improving initial referencing accuracy, as well as rereferencing accuracy in cases of multilevel instrumentation or in cases of dislocation of the reference array. Navigation-assisted spine surgery has become standard of care in most hospitals performing complex spine interventions. Although short-segment instrumentations are fairly straight-forward with current hardware and software solutions, obtaining ideal accuracies and troubleshooting reference array disruptions remain challenging. A surgical technique is presented as a step-by-step guide using intraoperative videos and photographs as well as imaging data in an illustrative case of thoracic hemivertebra resection and dorsal instrumentation. After skin incision is performed at the index level, posterior soft tissue preparation is performed. Before firmly attaching the reference array to a spinous process we then insert a minimum of four 5 mm mini screws at any bony structure within the exposure. Then an intraoperative navigation scan (3-dimensional computed tomography or x-ray) is obtained, and initial referencing is performed using the previously inserted mini screws as landmarks. This yields mean accuracies of 1 mm or lower and is easily verifiable by placing the navigation probe on a mini screw head. This action can be swiftly repeated at any time to prevent reduced accuracy because of insertion forces applied during pedicle screw placement. In addition, this allows for easy rereferencing in cases of disruption or complete removal of the navigation array, eliminating the need to perform additional computed tomography or x-ray scans during the procedure. The technique presented allows for rapid and highly accurate initial referencing and can be used in all cases of navigation-assisted spine surgery. It also allows for hassle-free rereferencing in cases of disruption or accidental removal of the reference array.

The Impact of Single-Vendor Procurement of Spinal Implants: An Analysis of Cost Savings and Surgical Quality at an Academic Hospital

Abstract INTRODUCTION In 2011, our institution abandoned a multi-vendor strategy of purchasing commodity spinal implants, such as pedicle screws and plates, in favor of a dual-vendor model. In 2015, facing ongoing budgetary constraints, we advanced to a sole supplier of these devices. The objective of this study was to report the savings created by the dual-vendor and single-vendor purchasing of spinal implants, and to assess whether vendor rationalization affected the quality-of-care at our institution. METHODS Patients receiving single-level lumbar interbody fusion (CPT# 22630, 22633) at our institution between January 1, 2008 and July 31, 2017 were identified retrospectively. Patients were excluded if they had a multi-level fusion, prior instrumentation, or anterior fusion. Patients were grouped according to the number of vendors available to our surgeons at the time of the patient's surgery; the 2008 to 2010, 2011 to 2014, and 2015 to 2017 time periods were defined as the multi-vendor (10 vendors), dual-vendor, and single-vendor periods, respectively. Propensity score weighting was performed to control for potential confounding between the patient cohorts. Outcomes were defined as rates of 12-mo revision surgeries and patient-reported outcomes, as measured by EQ-5D/PROMIS-GH utilities. Annual cost savings associated with the dual-vendor and single-vendor periods are also reported. RESULTS A total of 1373 patients were analyzed. Rates of revision surgeries after propensity score weighting were 3.2%, 4.5%, and 3.0% for the multi-vendor (Neff = 177.2), dual-vendor (Neff = 546.6), and single-vendor periods (Neff = 418.2), respectively. Revision surgeries (P &lt; .01) and EQ-5D/PROMIS-GH utilities (P &lt; .01) were statistically equivalent across all three time periods and no association between purchasing and the quality-of-care was observed. The annual cost savings directly attributable to vendor rationalization were 24% and 21% for the dual-vendor and single-vendor periods, respectively. CONCLUSION The dual-vendor and single-vendor procurement of spinal implants resulted in significant cost savings for our institution without evidence of a detrimental impact on the quality-of-care provided.

Surgical options for osteoporotic vertebral compression fractures complicated with spinal deformity and neurologic deficit

IntroductionThis paper describes surgical options for Osteoporotic vertebral compression fracture (OVCF) with acute flexible or chronic rigid kyphosis, and pseudarthrosis complicated with pain and neurologic deficit. MethodsThis study has two components. a) A prospective clinical study of surgical treatment of 31 patients (age: 69±11 years) with either acute flexible or progressive pseudarthrotic kyphosis manifested with severe pain or neurological deficit between 2010 and 2014. Eleven patients exhibited neurocompression (Frankel B, C, D). Surgery consisted in indirect reduction, kyphoplasty, and short posterior instrumentation in 28 patients and multilevel instrumentation in three. b) The second component involved a literature search of OVCF complicated with acute or painful chronic deformities and neurologic deficit, managed with open surgical approach. ResultsIndirect reduction, kyphoplasty and short posterior stabilization can restore satisfactory anatomic alignment and neurological deficit. Multilevel instrumentation was used for rigid long kyphosis. Complications were related to a) screw pull out and junctional kyphosis (4 patients) one of the patients also developed anterior migration of cement, b) cement leakage (4 patients). L5 radiculopathy occurred in one patient. The others remained asymptomatic. The literature review concluded that corpectomy with anterior, posterior or combined instrumentations is indicated for burst fractures, or rigid kyphosis with neurocompression. Prompt decompression with anatomical alignment may restore paraplegia. Complications were germane to osteoporotic bone predisposing to hardware loosening or cut out and dislodgement of instrumentation. DiscussionNeurologic deficit associated with fractures or progressive pseudarthrotic kyphosis effectively may respond to indirect postural reduction, kyphoplasty and posterior percutaneous short segment transpedicle instrumentation. For burst fractures and rigid chronic kyphosis corpectomy reconstructed with cages and anterior, or posterior or combined instrumentations can restore and maintain normal anatomy. The following guidelines for optimal surgical instrumentation have been established: To prevent screw loosening and junctional kyphosis the instrumentation should not end within the kyphotic segment. Screws for anterior instrumentation should penetrate the contralateral cortex. Multiple site of fixation or combined anterior and posterior instrumentations dissipate stresses at any one site. Augmentation of transpedicle screw fixation with cement is a sound technical principle. Cement should inserted in a doughy state with minimal pressure to prevent cement complications.

Multilevel Instruments for Infrastructure Investment: Evaluating State Revolving Funds for Water

In recent decades, the federal government has introduced complex, multilevel state‐operated revolving loan fund programs as an instrument for promoting state and local investment in national infrastructure priorities while limiting direct federal involvement in implementation. A federally funded state revolving fund (SRF) program combines features of a categorical matching grant to states and a subsidized loan program to localities, both of which should lower the effective price of infrastructure investment and therefore promote higher levels of infrastructure investment. However, little evidence exists to date on whether these programs stimulate new subnational spending or instead displace spending that would have occurred otherwise. We evaluate the stimulus effects of SRFs by examining the two largest such programs, the Clean Water and the Drinking Water SRF Programs. Analyzing 17 years of state‐level panel data, we find evidence that the flow of federal funds to states under the SRF programs stimulates new local investment in wastewater infrastructure, but not in drinking water infrastructure. In discussing several possible explanations for these divergent results, we argue for further research that emphasizes the intergovernmental features of this financing tool.

Stand-Alone Anterior Cervical Decompression and Fusion in Three Levels with Peek Cages: A Possible Satisfactory Alternative

Anterior cervical decompression and fusion (ACDF) remains the gold standard for subaxial degeneration of anterior elements. By multilevel stenosis corpectomy or instrumentation with screws and plate are supported. Their potential complications, though, should be reckoned. The use of polyetheretherketone (PEEK) cages packed with demineralized bone matrix (DBM) alone can provide good fusion rates and clinical improvement even in cases of three levels degeneration. The purpose of this paper is to present retrospectively the outcomes of 15 patients with cervical stenosis in three levels treated with cage implantation reviewing the relevant literature, too.

Experimental Model of Proximal Junctional Fracture after Multilevel Posterior Spinal Instrumentation.

There is a high risk of proximal junctional fractures (PJF) with multilevel spinal instrumentation, especially in the osteoporotic spine. This problem is associated with significant morbidity and possibly the need for reoperation. Various techniques have been proposed in an attempt to decrease the risk of PJF but there is no experimental model described for in vitro production of PJF after multilevel instrumentation. The objective of this study is to develop an experimental model of PJF after multilevel posterior instrumentation. Initially, four porcine specimens including 4 vertebrae and instrumented at the 3 caudal vertebrae using a pedicle screw construct were subjected to different loading conditions. Loading conditions on porcine specimens involving cyclic loading along the axis of the center vertebral body line, with constrained flexion between 0° and 15° proximally, and fully constraining the specimen distally resulted in a fracture pattern most representative of a PJF seen clinically in humans, so to undergo human cadaveric testing with similar loading conditions was decided. Clinically relevant PJF were produced in all 3 human specimens. The experimental model described in this study will allow the evaluation of different parameters influencing the incidence and prevention of PJF after multilevel posterior spinal instrumentation.

Biomechanical Analysis of the Proximal Adjacent Segment after Multilevel Instrumentation of the Thoracic Spine: Do Hooks Ease the Transition?

Study Design Biomechanical cadaveric study. Objective Clinical studies indicate that using less-rigid fixation techniques in place of the standard all-pedicle screw construct when correcting for scoliosis may reduce the incidence of proximal junctional kyphosis and improve patient outcomes. The purpose of this study is to investigate whether there is a biomechanical advantage to using supralaminar hooks in place of pedicle screws at the upper-instrumented vertebrae in a multilevel thoracic construct. Methods T7–T12 spines were biomechanically tested: (1) intact; (2) following a two-level pedicles screw fusion from T9 to T11; and after proximal extension of the fusion to T8–T9 with (3) bilateral supra-laminar hooks, (4) a unilateral hook + unilateral screw hybrid, or (5) bilateral pedicle screws. Specimens were nondestructively loaded while three-dimensional kinematics and intradiscal pressure at the supra-adjacent level were recorded. Results Supra-adjacent hypermobility was reduced when bilateral hooks were used in place of pedicle screws at the upper-instrumented level, with statistically significant differences in lateral bending and torsion (p < 0.05 and p < 0.001, respectively). Disk pressures in the supra-adjacent segment were not statistically different among top-off techniques. Conclusions The use of supralaminar hooks at the top of a multilevel posterior fusion construct reduces the stress at the proximal uninstrumented motion segment. Although further data is needed to provide a definitive link to the clinical occurrence of PJK, this in vitro study demonstrates the potential benefit of “easing” the transition between the stiff instrumented spine and the flexible native spine and is the first to demonstrate these results with laminar hooks.

Radionuclide Evaluation of Pulmonary Perfusion in Patients with Severe Thoracic Scoliosis Before and After Surgery

The purpose of the study was to evaluate the influence of severe scoliosis surgical correction upon pulmonary microcirculation. The study included 8 patients aged 12— 27 years with severe thoracic scoliosis. Angle deformity by Cobb ranged from 80 to 140° (mean 120.4°). Deformity correction and fixation was performed on the concave side of thorax using multilevel CotrelDubousset instrumentation (CDI) and elevating thoracoplasty (ET). Perfusion radionuclide pulmonary scintigraphy was performed prior to, 3 months and 1 year after surgery. Analysis of pulmonary scintigrams included both the qualitative (visual) and quantitative assessments. Besides, examination of external respiration function (spirometry and spirography) was performed. Mean postoperative Cobb angle made up 67.4°. No loss of correction was noted. Prior to surgical intervention pulmonary scintigrams showed deformation of lung fields, displacement along the vertical axis towards opposite to curvature side, decreased perfusion in the zone of intercostal retraction on the concave side of thorax. Postoperatively restoration of vertical axis, increase of lungs size and improvement of perfusion were observed. Mean vital lung capacity increased from 1510 (540-2280) to 2090 (640-3010) ml. Thus, combined application of CDI and ET enabled to perform adequate correction of severe thoracic scoliosis as well as to improve pulmonary microcirculation and radionuclide perfusion scintigraphy was a highly informative method for the evaluation of lung condition.