Jean Ouellet

DNA methylation of SPARC and chronic low back pain.

BackgroundThe extracellular matrix protein SPARC (Secreted Protein, Acidic, Rich in Cysteine) has been linked to degeneration of the intervertebral discs and chronic low back pain (LBP). In humans, SPARC protein expression is decreased as a function of age and disc degeneration. In mice, inactivation of the SPARC gene results in the development of accelerated age-dependent disc degeneration concurrent with age-dependent behavioral signs of chronic LBP.DNA methylation is the covalent modification of DNA by addition of methyl moieties to cytosines in DNA. DNA methylation plays an important role in programming of gene expression, including in the dynamic regulation of changes in gene expression in response to aging and environmental signals.We tested the hypothesis that DNA methylation down-regulates SPARC expression in chronic LBP in pre-clinical models and in patients with chronic LBP.ResultsOur data shows that aging mice develop anatomical and behavioral signs of disc degeneration and back pain, decreased SPARC expression and increased methylation of the SPARC promoter. In parallel, we show that human subjects with back pain exhibit signs of disc degeneration and increased methylation of the SPARC promoter. Methylation of either the human or mouse SPARC promoter silences its activity in transient transfection assays.ConclusionsThis study provides the first evidence that DNA methylation of a single gene plays a role in chronic pain in humans and animal models. This has important implications for understanding the mechanisms involved in chronic pain and for pain therapy.

Surgical Technique: Modern Luqué Trolley, a Self-growing Rod Technique

BackgroundThe challenge when managing early-onset scoliosis (EOS) is to prevent curve progression while maintaining spinal growth. Current surgical treatments (growing rods, VEPTR) require repetitive interventions to lengthen the implants.Questions/purposesWe asked whether a modern Luqué trolley construct could achieve and maintain scoliosis correction in EOS during spinal growth without the need for repetitive surgeries, thus decreasing the morbidity of the surgical treatment.MethodsWe retrospectively reviewed five patients who underwent a modern Luqué trolley construct between 2003 and 2008. This construct consists of inserting apical gliding spinal anchors using muscle-sparing techniques to the proximal and distal fixed anchors found in the dual growing rod construct. We documented age at surgery, correction and maintenance of deformity, spinal growth, number of procedures, and complications.ResultsThe primary curve was corrected from 60° to 21° and was maintained at 21° at a minimum followup of 2xa0years (mean, 4xa0years; range, 2–5.5xa0years). An average of 10 vertebrae was spanned allowing the spine to grow a mean of 3xa0cm over 4xa0years, representing a mean of 77% of the expected growth. Two of the five cases outgrew the construct requiring lengthening of rods. One patient had gradual recurrence of deformity without substantial axial growth that required revision surgery after 4xa0years.ConclusionModifications of the Luqué trolley may be useful for managing EOS without the morbidity of repetitive surgery. However, questions such as the effect of wear debris and the risk of spontaneous fusions still remain.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The Relationship between Preoperative Expectations and the Short-Term Postoperative Satisfaction and Functional Outcome in Lumbar Spine Surgery: A Systematic Review

Study Design Systematic review. Objective To examine the relationship between the patients preoperative expectations and short-term postoperative satisfaction and functional outcome in lumbar spine surgery. Methods The Medline, Embase, and Cochrane databases were queried using a predefined search algorithm to identify all lumbar spine studies analyzing the influence of preoperative expectations on postoperative satisfaction and functional outcome. Two independent reviewers and a third independent mediator reviewed the literature and performed study screening, selection, methodological assessment, and data extraction using an objective protocol. Results Of 444 studies identified, 13 met the inclusion criteria. Methodological quality scores ranged from 59 to 100% with the greatest variability in defining patient characteristics and the methods of assessing patient expectations. Patient expectations were assessed in 22 areas, most frequently back and leg pain expectations and general expectations. Functional outcome was assessed by 13 tools; the most common were the visual analog scale, Oswestry Disability Index (ODI), and Short Form Health Survey (SF-36). Positive expectations for symptomatology, activity, general health, and recovery correlated with satisfaction. General expectations correlated with higher SF-36 Physical Subcomponent scores, better global function, and lower ODI outcome. Conclusions on the influence of the expectations for pain were limited due to the study heterogeneity, but the evidence suggests a positive correlation between the expectation and outcome for back and leg pain. Conclusions Positive expectations correlated significantly with short-term postoperative satisfaction and functional outcome, including higher SF-36 scores, earlier return to work, and decreased ODI scores. Future expectation-based investigations will benefit from implementation of the standardized methods of expectation, satisfaction, and outcome analysis discussed herein.

Incidence, Predictors, and Postoperative Complications of Blood Transfusion in Thoracic and Lumbar Fusion Surgery: An Analysis of 13,695 Patients from the American College of Surgeons National Surgical Quality Improvement Program Database

Study Design Retrospective cohort study. Objective To identify predictive factors for blood transfusion and associated complications in lumbar and thoracic fusion surgeries. Methods The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent lumbar or thoracic fusion from 2010 to 2013. Multivariate analysis was used to determine predictive factors and postoperative complications associated with transfusion. Results Out of 13,695 patients, 13,170 had lumbar fusion and 525 had thoracic fusion. The prevalence of transfusion was 31.8% for thoracic and 17.0% for lumbar fusion. The multivariate analysis showed that age between 50 and 60, age between 61 and 70, ageu2009>u200970, dyspnea, American Society of Anesthesiologists class 3, bleeding disease, multilevel surgery, extended surgical time, return to operation room, and higher preoperative blood urea nitrogen (BUN) were predictors of blood transfusion for lumbar fusion. Multilevel surgery, preoperative BUN, and extended surgical time were predictors of transfusion for thoracic fusion. Patients receiving transfusions who underwent lumbar fusion were more likely to develop wound infection, venous thromboembolism, pulmonary embolism, and myocardial infarction and had longer hospital stay. Patients receiving transfusions who underwent thoracic fusion were more likely to have extended hospital stay. Conclusion This study characterizes incidence, predictors, and postoperative complications associated with blood transfusion in thoracic and lumbar fusion. Pre- and postoperative planning for patients deemed to be at high risk of requiring blood transfusion might reduce postoperative complications in this population.

The Outcome of Using Closed Suction Wound Drains in Patients Undergoing Lumbar Spine Surgery: a Systematic Review

Study Design Systematic review. Objective Determine whether closed suction wound drains decrease the incidence of postoperative complications compared with no drain use in patients undergoing spine surgery for lumbar degenerative conditions. Methods Electronic databases and reference lists of key articles were searched up through January 22, 2015, to identify studies comparing the use of closed suction wound drains with no drains in spine surgery for lumbar degenerative conditions. Outcomes assessed included the cumulative incidence of epidural hematoma, superficial and deep wound infection, and postoperative blood transfusion. The overall strength of evidence across studies was based on precepts outlined by the Grades of Recommendation Assessment, Development and Evaluation Working Group. Results Five heterogeneous studies, three randomized controlled trials, and two cohort studies form the evidence basis for this report. There was no difference in the incidence of hematoma, superficial wound infection, or deep infection in patients with compared with patients without closed suction wound drains after lumbar surgery. The upper bounds of the 95% confidence interval for hematoma ranged from 1.1 to 16.7%; for superficial infection, 1.0 to 7.3%; and for deep infection, 1.0 to 7.1%. One observational study reported a 3.5-fold increase in the risk of blood transfusion in patients with a drain. The overall strength of evidence for these findings is considered low or insufficient. Conclusions Conclusions from this systematic review are limited by the quality of included studies that assessed the use of closed suction wound drains in lumbar spine surgeries for degenerative conditions. We believe that spine surgeons should not routinely rely on closed suction wound drains in lumbar spine surgery until a higher level of evidence becomes available to support its use.

The revised Tokuhashi score; analysis of parameters and assessment of its accuracy in determining survival in patients afflicted with spinal metastasis

PurposeTo determine the significance of each parameter of the revised Tokuhashi score and identify which is associated with survival.BackgroundSpinal metastases are common and can be a challenging medical issue. Treatment options depend on patients’ prognosis. Many scoring systems in the literature help estimate prognosis, such as the Tokuhashi, revised Tokuhashi, and Tomita scoring systems.MethodsA retrospective review of all patients from 2003 to 2012 treated for spinal metastases in one center was conducted. Imaging, pathology, and charts were reviewed to determine the modified Tokuhashi scores. Scores were then compared to the actual documented survival. Univariate and multiple regression analyses were used to assess the importance of each individual parameter and survival time. Linear regression was used to determine the relationship between the Tokuhashi score and weighted Tokuhashi score with survival time.ResultsA total of 126 patients were reviewed. All parameters in the revised Tokuhashi score were significantly associated with survival time except for primary site using univariate analysis. Only the number of spinal metastases and metastasis to major organs showed statistical significance when multiple variable analysis was used.ConclusionA number of spinal metastases and metastasis to major organs were the most important predictors of actual survival. Modification to the score based on population characteristics would help better identify patients with spinal metastases that can benefit from surgery.

Differences between Manufacturers of Computed Tomography-Based Computer-Assisted Surgery Systems Do Exist: A Systematic Literature Review

Study Design Literature review. Objective Several studies have shown that the accuracy of pedicle screw placement significantly improves with use of computed tomography (CT)-based navigation systems. Yet, there has been no systematic review directly comparing accuracy of pedicle screw placement between different CT-based navigation systems. The objective of this study is to review the results presented in the literature and compare CT-based navigation systems relative only to screw placement accuracy. Methods Data sources included CENTRAL, Medline, PubMed, and Embase databases. Studies included were randomized clinical trials, case series, and case–control trials reporting the accuracy of pedicle screws placement using CT-based navigation. Two independent reviewers extracted the data from the selected studies that met our inclusion criteria. Publications were grouped based on the CT-based navigation system used for pedicle screw placement. Results Of the 997 articles we screened, only 26 met all of our inclusion criteria and were included in the final analysis, which showed a significant statistical difference (pu2009<u20090.0001, 95% confidence interval 0.92 to 1.23) in accuracy of pedicle screw placement between three different CT-based navigation systems. The mean (weighted) accuracy of pedicle screws placement based on the CT-based navigation system was found to be 97.20u2009±u20092.1% in StealthStation (Medtronic, United States) and 96.1u2009±u20093.9% in VectorVision (BrainLab, Germany). Conclusion This review summarizes results presented in the literature and compares screw placement accuracy using different CT-based navigation systems. Although certain factors such as the extent of the procedure and the experience and skills of the surgeon were not accounted for, the differences in accuracy demonstrated should be considered by spine surgeons and should be validated for effects on patients’ outcome.

Bilateral vascularized rib grafts to promote spinopelvic fixation in patients with sacral agenesis and spinopelvic dissociation: a new surgical technique

BACKGROUND CONTEXTnSacral agenesis is a rare congenital disorder that may have spinopelvic instability due to sacroiliac joint malformation. Surgical indication in patients with sacral agenesis is to improve their sitting balance and protect the visceral organs. Achieving solid arthrodesis across this congenital malformation is challenging and prone to non-union.nnnPURPOSEnThe purpose of this study was to describe a novel surgical technique with vascularized ribs for management of sacral agenesis and complex spinopelvic dissociation.nnnSTUDY DESIGNnRetrospective study.nnnPATIENT SAMPLEnSix patients with sacral agenesis were reviewed and followed for a mean of 8.5 years after spinopelvic fusion augmented with vascularized rib graft spanning the lumbo-pelvic junction.nnnOUTCOME MEASURESnThe primary outcome measure was the presence or absence of a stable spinopelvic junction and fusion across the spine-vascular rib grafts-pelvis interface. The secondary outcome measures were maintenance of pelvic obliquity, lumbosacral kyphosis, and overall sagittal balance.nnnMETHODSnThe surgical procedure consisted of two-stage surgeries performed 6-12 weeks apart. The first stage consisted of spinal instrumentation and correction of the deformity via a posterior approach and impaction of one of the vascularized ribs from the spine to the iliac crest. The second stage consisted of an anterior thoraco-lumbar approach for spinal fusion and the second vascularized rib spanning the spine to the iliac crest.nnnRESULTSnAll six patients eventually achieved a solid spinal and spinopelvic fusion. All vascularized ribs increased in diameter over time. A high complication rate consisted mainly of spinal infections and prominent hardware requiring revision surgeries (a total of seven procedures in four patients). Two patients had decreased mobility secondary to spinopelvic surgery at last follow-up.nnnCONCLUSIONSnSpinopelvic fusion can be successfully achieved with this novel surgical technique using vascularized rib grafts. This technique allows for biological long-term maintenance of the sagittal deformity correction. Fusion across the lumbosacral junction in patients with sacral agenesis may place them at risk of losing the ability to mobilize independently. Recent lower profile implants have prevented implant-related complications.

Does Balloon Kyphoplasty Deliver More Cement Safely into Osteoporotic Vertebrae with Compression Fractures Compared with Vertebroplasty? A Study in Vertebral Analogues:

Study Design A biomechanical and radiographic study using vertebral analogues. Objectives Kyphoplasty and vertebroplasty are widely used techniques to alleviate pain in fractures secondary to osteoporosis. However, cement leakage toward vital structures like the spinal cord can be a major source of morbidity and even mortality. We define safe cement injection as the volume of the cement injected into a vertebra before the cement leakage occurs. Our objective is to compare the amount of cement that can be safely injected into an osteoporotic vertebra with simulated compression fracture using either vertebroplasty or balloon kyphoplasty techniques. Methods Forty artificial vertebral analogues made of polyurethane with osteoporotic cancellous matrix representing the L3 vertebrae were used for this study and were divided into four groups of 10 vertebrae each. The four groups tested were: low-viscosity cement injected using vertebroplasty, high-viscosity cement injected using vertebroplasty, low-viscosity cement injected using balloon kyphoplasty, and high-viscosity cement injected using balloon kyphoplasty. The procedures were performed under fluoroscopic guidance. The injection was stopped when the cement started protruding from the created vascular channel in the osteoporotic vertebral fracture model. The main outcome measured was the volume of the cement injected safely into a vertebra before leakage through the posterior vascular channel. Results The highest volume of the cement injected was in the vertebroplasty group using high-viscosity cement, which was almost twice the injected volume in the other three groups. One-way analysis of variance comparing the four groups showed a statistically significant difference (pu2009<u20090.005). Conclusions High-viscosity cement injected using vertebroplasty delivers more cement volume before cement leakage and fills the vertebral body more uniformly when compared with balloon kyphoplasty in osteoporotic vertebrae with compression fractures.

Postoperative Assessment of Pedicle Screws and Management of Breaches: A Survey among Canadian Spine Surgeons and a New Scoring System

Study Design This study was designed as a survey amongst Canadian spine surgeon to determine a scoring system to standardize pedicle screw placement assessment. Purpose This study aimed to obtain and analyze the opinions of spine surgeons regarding the assessment of pedicle screw accuracy, with the goal of establishing clinical guidelines for interventions for malpositioned pedicle screws. Overview of Literature Accurate placement of pedicle screws is challenging, and misalignment can lead to various complications. To date, there is no recognized gold standard for assessing pedicle screw placement accuracy. The literature is lacking studies attempting to standardize pedicle screw placement accuracy assessment. Methods A survey of the clinical methods and imaging criteria that are used for assessing pedicle screw placement accuracy was designed and sent to orthopedic and neurosurgery spine surgeons from the Canadian Spine Society for their anonymous participation. Results Thirty-five surgeons completed the questionnaire. The most commonly used modalities for assessing pedicle screw position postoperatively were plain X-rays (97%) and computed tomography (CT, 97%). In both symptomatic and asymptomatic patients, the most and least worrisome breaches were medial and anterior breaches, respectively. The majority of surgeons tended not to re-operate on asymptomatic breaches. More than 60% of surgeons would re-operate on patients with new-onset pain and a ≤4-mm medial or inferior breach in both thoracic and lumbar regions. If a patient experienced sensory loss and a breach on CT, in either the thoracic or lumbar levels, 90% and 70% of the surgeons would re-operate for a medial breach and an inferior breach, respectively. Conclusions Postoperative clinical presentation and imaging findings are crucial for interpreting aberrant pedicle screw placement. This study presents a preliminary scoring system for standardizing the classification of pedicle screws.