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Biomedical subjects

Marcel Dvorak

Publications and source records attributed to Marcel Dvorak.

12 recordsLinked to original sources
PubMed2006

Cost-effectiveness of surgery plus radiotherapy versus radiotherapy alone for metastatic epidural spinal cord compression.

PURPOSE: A recent randomized clinical trial has demonstrated that direct decompressive surgery plus radiotherapy was superior to radiotherapy alone for the treatment of metastatic epidural spinal cord compression. The current study compared the cost-effectiveness of the two approaches. METHODS AND MATERIALS: In the original clinical trial, clinical effectiveness was measured by ambulation and survival time until death. In this study, an incremental cost-effectiveness analysis was performed from a societal perspective. Costs related to treatment and posttreatment care were estimated and extended to the lifetime of the cohort. Weibull regression was applied to extrapolate outcomes in the presence of censored clinical effectiveness data. RESULTS: From a societal perspective, the baseline incremental cost-effectiveness ratio (ICER) was found to be $60 per additional day of ambulation (all costs in 2003 Canadian dollars). Using probabilistic sensitivity analysis, 50% of all generated ICERs were lower than $57, and 95% were lower than $242 per additional day of ambulation. This analysis had a 95% CI of -$72.74 to 309.44, meaning that this intervention ranged from a financial savings of $72.74 to a cost of $309.44 per additional day of ambulation. Using survival as the measure of effectiveness resulted in an ICER of $30,940 per life-year gained. CONCLUSIONS: We found strong evidence that treatment of metastatic epidural spinal cord compression with surgery in addition to radiotherapy is cost-effective both in terms of cost per additional day of ambulation, and cost per life-year gained.

Canada↗
PubMed2006

Interobserver and intraobserver reliability of maximum canal compromise and spinal cord compression for evaluation of acute traumatic cervical spinal cord injury.

STUDY DESIGN: Prospective, blinded validation study of an objective, quantitative measure to assess maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) in individuals with acute cervical spinal cord injury (SCI). OBJECTIVE: To examine the intraobserver and interobserver reliability of MCC and MSCC in individuals with acute traumatic cervical SCI. SUMMARY OF BACKGROUND DATA: To date, few quantitative reliable radiologic methods for assessing the extent of spinal cord compression in the setting of acute SCI have been reported. MCC and MSCC, as assessed on mid-sagittal CT and T2-weighted MR images, respectively, appear to have potential clinical and prognostic value. To date, the validation of these assessment tools has been limited to a small number of observers at a single institution. However, to date no study has focused on the reliability of these radiologic parameters among a large cohort of spine surgeons from North America and abroad. This type of validation is critical to allow the broader use of these outcome measures in research studies and in clinical practice. METHODS: Mid-sagittal MRI and CT images of cervical spine were selected from 10 individuals with acute traumatic cervical SCI. A total of 28 spine surgeons independently estimated CT MCC, T1-weighted MRI MCC, and T2-weighted MRI MSCC on two occasions using a calibrated ruler. In the first round of measurements, the observers estimated the radiologic parameters using only written instructions. The second measurement set was obtained after an interactive teaching session on the methodology. The order of the images was altered for the second set of measurements. RESULTS: Analysis using parametric and nonparametric statistics indicated high intraobserver reliability for CT MCC, T1-weighted MRI MCC, and T2-weighted MSCC with interclass correlation coefficients (ICCs) of 0.92, 0.95, and 0.97, respectively. The interobserver reliability for all three radiologic parameters was considered moderate with ICCs ranging from 0.35 to 0.56. CONCLUSION: Our results indicate that the intraobserver reliability for the MCC and MSCC was high. Although the interobserver reliability for all three radiologic parameters in the present study was below 0.75, the observed differences were small and largely accounted for by the limitations in the precision of the calibrated ruler. For cases with minimal cord compression, the measurement of canal stenosis (MCC) proved more accurate. In contrast, in cases with severe cord compression, the assessment of MSCC was more accurate. It is anticipated that the use of digital imaging technologies will further enhance the precision of these outcome measures.

Acute Disease↗
PubMed2006

Radiographic measurement parameters in thoracolumbar fractures: a systematic review and consensus statement of the spine trauma study group.

STUDY DESIGN: Systematic review. OBJECTIVES: To review the various radiographic parameters currently used to assess traumatic thoracolumbar injuries, emphasizing the validity and technique behind each one, to formulate evidence-based guidelines for a standardized radiographic method of assessment of these fractures. SUMMARY OF BACKGROUND DATA: The treatment of thoracolumbar fractures is guided by various radiographic measurement parameters. Unfortunately, for each group of parameters, there has usually been more than 1 proposed measurement technique, thus creating confusion when gathering data and reporting outcomes. Ultimately, this effect results in clinical decisions being based on nonstandardized, nonvalidated outcome measures. METHODS: Computerized bibliographic databases were searched up to January 2004 using key words and Medical Subject Headings on thoracolumbar spine trauma, radiographic parameters, and methodologic terms. Using strict inclusion criteria, 2 independent reviewers conducted study selection, data abstraction, and methodologic quality assessment. RESULTS: There were 18 original articles that ultimately constituted the basis for the review. Of radiographic measurement parameters, 3 major groups were identified, depicting the properties of the injured spinal column: sagittal alignment, vertebral body compression, and spinal canal dimensions, with 14 radiographic parameters reported to assess these properties. CONCLUSIONS: Based on a systematic review of the literature and expert opinion from an experienced group of spine trauma surgeons, it is recommended that the following radiographic parameters should be used routinely to assess thoracolumbar fractures: the Cobb angle, to assess sagittal alignment; vertebral body translation percentage, to express traumatic anterolisthesis; anterior vertebral body compression percentage, to assess vertebral body compression, the sagittal-to-transverse canal diameter ratio, and canal total cross-sectional area (measured or calculated); and the percent canal occlusion, to assess canal dimensions.

Consensus↗
PubMed2006

Measurement techniques for lower cervical spine injuries: consensus statement of the Spine Trauma Study Group.

STUDY DESIGN: Literature review. OBJECTIVES: It was the purpose of the Spine Trauma Study Group to compile a collection of clinically useful imaging methods used in lower cervical spine trauma and to describe in detail how these measurements should be made. SUMMARY OF BACKGROUND DATA: Injury detection, description, and treatment decision-making rely on accurate imaging of the lower cervical spine. However, a standard set of imaging measurement techniques for this region does not exist. While most clinicians have developed their own methods of describing radiographic pathology, this variability often leads to confusion in developing an agreed on classification system and limits treatment recommendations. METHODS: The available literature concerning measurement of injury characteristics after lower cervical trauma was reviewed. Consensus of the most potentially useful measurement methods among the surgeon members of the Spine Trauma Study Group was achieved. RESULTS: These measurements included the following: kyphosis (Cobb angle and posterior vertebral body tangent methods); vertebral body translation; vertebral body height loss; maximal spinal canal compromise and spinal cord compression; facet fracture fragment size; and percentage facet subluxation. CONCLUSIONS: A consistent and standard measurement technique among clinicians with regards to imaging of lower cervical spine trauma should positively influence treatment outcome. However, it is through prospective study that the clinical significance of these recommendations will be scientifically established.

Cervical Vertebrae↗
PubMed2006

Surgical decision making for unstable thoracolumbar spine injuries: results of a consensus panel review by the Spine Trauma Study Group.

OBJECTIVES: The optimal surgical approach and treatment of unstable thoracolumbar spine injuries are poorly defined owing to a lack of widely accepted level I clinical literature. This lack of evidence-based standards has led to varied practice patterns based on individual surgeon preferences. The purpose of this study was to survey the leaders in the field of spine trauma to define the major characteristics of thoracolumbar injuries that influence their surgical decision making. In the absence of good scientific data, expert consensus opinions may provide surgeons with a practical framework to guide therapy and to conduct future research. METHODS: A panel of 22 leading spinal surgeons from 20 level I trauma centers in seven countries met to discuss the indications for surgical approach selection in unstable thoracolumbar injuries. Injuries were presented to the surgeons in a case scenario survey format. Preferred surgical approaches to the clinical scenarios were tabulated and comments weighed. RESULTS: All members of the panel agreed that three independent characteristics of thoracolumbar injuries carry primary importance in surgical decision making: the injury morphology, the neurologic status of the patient, and the integrity of the posterior ligaments. Six clinical scenarios based on the neurologic status of the patient (intact, incomplete, or complete) and on the status of the posterior ligamentous complex (intact or disrupted) were created, and consensus treatment approaches were described. Additional circumstances capable of altering the treatments were acknowledged. CONCLUSIONS: Decision making for the surgical treatment of thoracolumbar injuries is largely dependent on three patient characteristics: injury morphology, neurologic status, and posterior ligament integrity. A logical and practical decision-making process based on these characteristics may guide treatment even for the most complicated fracture patterns.

Algorithms↗
PubMed2006

Agreement between orthopedic surgeons and neurosurgeons regarding a new algorithm for the treatment of thoracolumbar injuries: a multicenter reliability study.

INTRODUCTION: Considerable variability exists in the management of thoracolumbar (TL) spine injuries. Although there are many influences, one significant factor may be the treating surgeon's specialty and training (ie, orthopedic surgery vs. neurosurgery). Our objective was to assess the agreement between spinal orthopedic and neurologic surgeons in rating the severity of TL spine injuries with a new treatment algorithm. This information could be important in establishing consensus-based protocols for managing these challenging injuries. METHODS: Twenty-eight spinal surgeons (8 neurosurgeons and 20 orthopedic surgeons) reviewed 56 TL injury case histories. Each case was classified and scored according to the TL injury severity score (TLISS). The case histories were reordered and the physicians repeated the exercise 3 months later. At both intervals the surgeons were asked if they agreed with the final treatment recommendation of the TLISS algorithm. The reliability and decision validity of the TLISS was compared. RESULTS: Between-group interrater reliability was similar to within group reliabilities. Intrarater reliability was also similar between groups. The between speciality interrater reliability of the TLISS management recommendation was moderate (74% agreement, kappa=0.532). Orthopedic and neurosurgeons agreed with the TLISS management recommendation 91.4% and 94.4% of the time, respectively. CONCLUSIONS: The TLISS demonstrated good reliability in terms of intraobserver and interobserver agreement on the algorithmic treatment recommendations. The recommendation for operation seems to be consistent between fellowship-trained orthopedic and neurosurgical spine surgeons. This type of classification system may reduce the existing variability and initial management decision for treatment of TL injuries.

Algorithms↗
PubMed2005

A new classification of thoracolumbar injuries: the importance of injury morphology, the integrity of the posterior ligamentous complex, and neurologic status.

STUDY DESIGN: A new proposed classification system for thoracolumbar (TL) spine injuries, including injury severity assessment, designed to assist in clinical management. OBJECTIVE: To devise a practical, yet comprehensive, classification system for TL injuries that assists in clinical decision-making in terms of the need for operative versus nonoperative care and surgical treatment approach in unstable injury patterns. SUMMARY OF BACKGROUND DATA: The most appropriate classification of traumatic TL spine injuries remains controversial. Systems currently in use can be cumbersome and difficult to apply. None of the published classification schemata is constructed to aid with decisions in clinical management. METHODS: Clinical spine trauma specialists from a variety of institutions around the world were canvassed with respect to information they deemed pivotal in the communication of TL spine trauma and the clinical decision-making process. Traditional injury patterns were reviewed and reconsidered in light of these essential characteristics. An initial validation process to determine the reliability and validity of an earlier version of this system was also undertaken. RESULTS: A new classification system called the Thoracolumbar Injury Classification and Severity Score (TLICS) was devised based on three injury characteristics: 1) morphology of injury determined by radiographic appearance, 2) integrity of the posterior ligamentous complex, and 3) neurologic status of the patient. A composite injury severity score was calculated from these characteristics stratifying patients into surgical and nonsurgical treatment groups. Finally, a methodology was developed to determine the optimum operative approach for surgical injury patterns. CONCLUSIONS: Although there will always be limitations to any cataloging system, the TLICS reflects accepted features cited in the literature important in predicting spinal stability, future deformity, and progressive neurologic compromise. This classification system is intended to be easy to apply and to facilitate clinical decision-making as a practical alternative to cumbersome classification systems already in use. The TLICS may improve communication between spine trauma physicians and the education of residents and fellows. Further studies are underway to determine the reliability and validity of this tool.

Humans↗
PubMed2005

The thoracolumbar injury severity score: a proposed treatment algorithm.

OBJECTIVE: Significant controversy exists regarding the optimal management of thoracolumbar injuries. This is in part due to the lack of understanding of the natural history of various injury subtypes and the absence of a universally accepted classification scheme that facilitates communication among care providers and assists in directing treatment. The Spine Trauma Study Group has developed an injury severity score based on three major variables: the mechanism of injury determined by radiographic appearance, the integrity of the posterior ligamentous complex, and the neurologic status of the patient. By systematically assigning specific point values within each category based on the severity of injury, a final severity score may be generated that can be used to help direct treatment. The goal of this work is to present a proposal of a detailed treatment algorithm to assist in the nonoperative or operative management of thoracolumbar injuries. METHODS: A detailed review of the world's spinal literature was performed to ascertain predictors of instability following thoracolumbar trauma. With use of known biomechanical and clinical outcome measures, an arbitrary assignment of point values to various injury descriptors was performed. The assessment of the validity of the severity score was compared retrospectively with a variety of selected cases representing the typical injury patterns under the three major injury groups: compression, translational/rotational, and distraction injuries. CONCLUSIONS: The proposed treatment algorithm is an attempt to assist physicians using best-evidence medicine in managing thoracolumbar spinal injuries. The final point flow chart with graduated treatment recommendations is only preliminary and needs to be validated through prospective cohort analysis. In addition, the importance of the chosen variables determining spinal stability must also be verified.

Algorithms↗
PubMed2004

Outcome evaluation of the operative management of lumbar disc herniation causing sciatica.

OBJECT: The authors conducted a study to assess health-related quality of life (HRQOL) and the appropriateness of surgery in patients who have undergone elective lumbar discectomy. METHODS: The study involved a prospective cohort of 82 surgically treated patients with lumbar disc herniation causing lower-extremity radiculopathy. An independent study coordinator recorded demographic data and administered the North American Spine Society (NASS) lumbar spine instrument and the Short Form-36 (SF-36) before treatment, and at 6 months and 1 year after surgery. The HRQOL results were also compared with normative data for the NASS and SF-36. The influence of baseline variables on HRQOL was determined using regression modeling. The InterQual Indicators for Surgery and Procedures (ISP) were used to compare surgeon practice patterns with standardized indications for surgery. The NASS neurogenic symptom (NSS) and pain/disability scores (PDSs) showed very significant improvement at 6 months and little change between 6 months and 1 year. The SF-36 physical function and bodily pain scale scores were associated with the greatest improvement. Interestingly, the 1-year NASS (NSS and PDS) and SF-36 (only PCS) scores remained lower than those of age-matched normative data. Other than preoperative HRQOL scores, the only other variable that inversely influenced HRQOL was the duration of time between symptom onset and surgery. Ninety-five percent of ISP forms were completed, and 97% of the indications recorded by the surgeon matched the criteria. CONCLUSIONS: The reporting of standardized outcomes in association with indications for surgery is feasible and may help elucidate the ideal rate for discectomy.

Adolescent↗
PubMed2003

Anterior cervical plate fixation: biomechanical effectiveness as a function of posterior element injury.

OBJECT: The primary goal of this study was to determine if the stabilization provided to the spine by anterior cervical fixation with plating (ACFP) was dependent on the degree of posterior element injury. The secondary goal was to evaluate the effectiveness of additional posterior screw/rod stabilization in these injuries. METHODS: Following ACFP with interbody bone graft and stepwise transection of the posterior ligaments and facets at C5-6, eight fresh-frozen human C4-7 spine segments were loaded using pure moments of +/- 1.5 Nm in flexion-extension, axial rotation, and lateral bending in the intact state. Posterior screw/rod fixation was performed after complete ligamentous destruction and complete removal of the facets. Repeated-measures analysis of variance and pairwise Student-Newman-Keuls tests were used to detect changes in the range of motion (ROM) and neutral zone (NZ). Statistical significance was assumed at a 95% level. Significant increases in ROM occurred in each loading direction after transection of the capsular ligaments (p < 0.001) and again following facetectomy (p < 0.001) compared with the ACFP condition. Additional posterior fixation resulted in a significant decrease in ROM in all loading directions (p < 0.001). There was a significant increase in NZ for complete ligamentous destruction compared with ACFP (p < 0.05) and facetectomy compared with ACFP (p < 0.05) for flexion-extension. In lateral bending, a significant increase in NZ was found for facetectomy compared with ACFP (p < 0.05). CONCLUSIONS: Capsular ligaments and articular facets are important structures in limiting three-dimensional vertebral motion in the presence of an anterior plate. Supplementary posterior fixation does reduce motion for all injury conditions.

Adult↗