News Article | April 17, 2017
TORONTO, ON--(Marketwired - April 12, 2017) - During a live broadcast on Wednesday, April 26, 2017, a panel of experts will discuss and examine embolic protection devices and the potential impact these may have on TAVR patients. Transcatheter aortic valve replacement (TAVR) or implantation (TAVI) demonstrably changed the treatment of high-risk patients with severe aortic stenosis, particularly those at high risk for surgical replacement of the aortic valve. However, greater acceptance of TAVR also raised concerns of complications, particularly increased risks for stroke or neurological and cognitive impairments from embolic events. The entry of embolic protection devices (EPD) into the European market, with designs that deflect or collect potentially damaging micro-debris associated with TAVR, presents an evolving risk-reduction safety strategy to manage patients with frail health or existing comorbidities. This webinar explores the potential for EPDs as well as factors Novella Clinical and Medical Metrics believe sponsors should consider when developing or using EPDs in clinical trials. To learn more about this complimentary event visit: Clinical Trial Considerations in Cerebral Protection for TAVR Patients -- An Examination of Study Design, Endpoints and Imaging Methods Xtalks, powered by Honeycomb Worldwide Inc., is a leading provider of educational webinars to the global Life Sciences community. Every year thousands of industry practitioners (from pharmaceutical & biotech companies, private & academic research institutions, healthcare centers, etc.) turn to Xtalks for access to quality content. Xtalks helps Life Science professionals stay current with industry developments, trends and regulations. Xtalks webinars also provide perspectives on key issues from top industry thought leaders and service providers. To learn more about Xtalks visit: http://xtalks.com
Sasso R.C.,Indiana University |
Metcalf N.H.,Medtronic Inc. |
Hipp J.A.,Medical Metrics Inc. |
Wharton N.D.,Medical Metrics Inc. |
Anderson P.A.,University of Wisconsin - Milwaukee
Spine | Year: 2011
Study Design.: Prospective, randomized, Food and Drug Administration Investigational Device Exemption trial from one study site. Objective.: Examine the radiographic sagittal alignment of the Bryan cervical disc for one-level disease. Summary of Background Data.: Prospective, randomized studies demonstrate Bryan arthroplasty provides statistically better functional outcomes than anterior cervical discectomy and fusion. Uncontrolled case reports describe kyphosis after disc replacement. No prospective study has critically assessed sagittal alignment after cervical arthroplasty. Methods.: Forty-eight patients reviewed with a minimum follow-up of 2 years. Quantitative motion analysis determined the change in overall (C2-C7) and treatment-level sagittal alignment, disc space heights, and range of motion. Results.: Preoperatively, overall sagittal alignment was equivalent in the two groups. At 24-month follow-up, overall lordosis for the cohorts was not statistically different from preoperative values for each group. In addition, overall lordosis was not significantly different at 24 months when comparing Bryan patients with the fusion patients. The average change in disc angle from preoperative to immediate postoperative at the treated level in the Bryan disc group was a nonsignificant increase in lordosis of 0.92°. The anterior disc height was the same at all time points, but the posterior disc height was slightly (0.7 mm) more in the Bryan than in the fusion patients (P = 0.04). The angular range of motion in the Bryan group was statistically equivalent at all time points. At the fused levels, average range of motion decreased from 6.4° to 0.9° at 24 months (P < 0.0001). Conclusion.: With the Bryan disc, there was an insignificant increase in lordosis of 0.9° at immediate postoperative time point. Overall cervical sagittal alignment is not different between the experimental and control populations. This prospective study does not demonstrate a clinically significant increase in segmental kyphosis after Bryan disc arthroplasty. Global cervical lordosis is statistically equivalent between arthroplasty and fusion groups at 2 years follow-up. Copyright © 2011 Lippincott Williams & Wilkins.
Prospective analysis of imaging prediction of pseudarthrosis after anterior cervical discectomy and fusion: Computed tomography versus flexion-extension motion analysis with intraoperative correlation
Ghiselli G.,Rose Spine Institute |
Wharton N.,Medical Metrics Inc |
Hipp J.A.,Medical Metrics Inc |
Wong D.A.,DenverSpine |
Spine | Year: 2011
Study Design. A prospective comparison of quantitative motion analyzed (QMA) flexion/extension radiographs versus computed tomography (CT) as an analytical predictor of cervical pseudarthrosis. Intraoperative confirmation of the fusion was performed. Objective. To prospectively compare motion analyzed flexion/extension radiographs to CT to predict pseudarthroses. Define motion thresholds on flexion/extension radiographs to define pseudarthroses. Summary Of Background Data. Assessment of postoperative fusion success is an important factor in assessing success after anterior cervical spine fusion. Gross intervertebral motion can be used as a measure; however, the current "gold standard" for determining fusion status is a CT to assess bridging bone. Defining the amount of intervertebral motion at the fusion site has been previously addressed and definitions have varied widely. Methods. Data were analyzed at 47 fusion segments. Intervertebral motion at the fusion site was measured from flexion/extension radiographs taken at least 1 year after the cervical spine fusion. Motion was quantified from digitized radiographs by an independent researcher using proprietary quantitative motion analysis (QMA) software. CT scans on all patients were analyzed for fusion status by a neuroradiologist. Those patients determined to have a symptomatic pseudarthrosis were revised and intraoperative motion at the facet joints was documented. Correlation between intraoperative findings, CT and QMA was performed. Results. Using greater than 4° of measured motion on flexion/extension radiographs resulted in a Spearman correlation P-value of 0.096 (95% confidence interval:-0.06 to 0.66). Using greater than 1° of motion, the Spearman correlation P < 0.0001 (95% CI: 0.54-0.90). The positive predictive value (PPV) using 4° of motion as the criterion was 100%, indicating a high specificity. The negative predictive value (NPV) was 52%, indicating a low sensitivity. Using greater than 1° of motion, the PPV was 100% and the NPV was 73%. Findings from CT showed an identical PPV and NPV to assessments made using greater than 1° of rotation. Specificity and positive predictive value were 100% for all criteria. Using a lack of bridging on CT or more than 1° of intervertebral motion during flexion/extension increased the sensitivity to 85% and the negative predictive value to 85%. Conclusion. A threshold level of 4° of motion is commonly used to identify a pseudarthrosis. Our prospective study suggests that this value has a high PPV, but a low specificity and would miss many of the pseudarthroses that have angular motion less than 4° (sensitivity 23%). By lowering the threshold for angular motion to 1°, the sensitivity improves to 77%. CT scan has been touted as the gold standard, and it has a high positive predictive value of 100%. However, its NPV was slightly lower than using 1° of motion on QMA analyzed flexion-extension films (73% vs. 79%). In conclusion, although CT scan has long been regarded as the gold standard for determining a pseudarthrosis in the cervical spine, the interpretation is subjective and vulnerable to both type I and type II errors. Analysis of motion using Quantitative Motion Analysis is seemingly less subjective than CT and in our prospective study was more predictive of an operatively confirmed pseudarthrosis. Copyright © 2011 Lippincott Williams &Wilkins.
Staub B.N.,Houston Methodist Neurological Institute |
Holman P.J.,Houston Methodist Neurological Institute |
Reitman C.A.,Baylor College of Medicine |
Hipp J.,Medical Metrics Inc.
Journal of Neurosurgery: Spine | Year: 2015
Object Evaluation of lumbar stability is fundamentally dependent on a clear understanding of normal lumbar motion. There are inconsistencies in reported lumbar motion across previously published studies, and it is unclear which provide the most reliable reference data. New technology now allows valid and reliable determination of normal lumbar intervertebral motion (IVM). The object of this study was to provide normative reference data for lumbar IVM and center of rotation (COR) using validated computer-assisted measurement tools. Methods?Sitting flexion-extension radiographs were obtained in 162 asymptomatic volunteers and then analyzed using a previously validated and widely used computerized image analysis method. Each lumbar level was subsequently classified as degenerated or nondegenerated using the Kellgren-Lawrence classification. Of the 803 levels analyzed, 658 were nondegenerated (Kellgren-Lawrence grade < 2). At each level of the lumbar spine, the magnitude of intervertebral rotation and translation, the ratio of translation per degree of rotation (TPDR), and the position of the COR were calculated in the nondegenerative cohort. Translations were calculated in millimeters and percentage endplate width. Results?All parameters were significantly dependent on the intervertebral level. The upper limit of the 95% CIs for anteroposterior intervertebral translation in this asymptomatic cohort ranged from 2.1 mm (6.2% endplate width) to 4.6 mm (13.3% endplate width). Intervertebral rotation upper limits ranged from 16.3 to 23.5. The upper limits for TPDR ranged from 0.49% to 0.82% endplate width/degree. The COR coordinates were clustered in level-dependent patterns. Conclusions?New normal values for IVM, COR, and the ratio of TPDR in asymptomatic nondegenerative lumbar levels are proposed, providing a reference for future interpretation of sagittal plane motion in the lumbar spine. © AANS 2015.
Anderson P.A.,University of Wisconsin - Madison |
Sasso R.C.,Indiana University |
Hipp J.,Medical Metrics Inc |
Norvell D.C.,Spectrum Research Inc |
And 2 more authors.
Spine | Year: 2012
Study Design. Systematic review and meta-analysis. Objective. To determine the kinematics of the adjacent segments and global cervical spine after cervical arthroplasty compared with anterior cervical discectomy and fusion (ACDF). Summary of Background Data: Adjacent segment pathology after ACDF is a significant concern. Arthroplasty may decrease the risk of adjacent segment degeneration by maintaining normal spinal kinematics compared with fusion. However, the differences in the in vivo kinematics of the adjacent segments after cervical fusion versus arthroplasty have not been clearly established. Methods. A systematic literature review of studies comparing adjacent segment kinematic changes between fusion and arthroplasty was performed. We included randomized controlled trials and cohort studies that compared cervical arthroplasty with ACDF in adults with degenerative disease and reported on at least 1 outcome of interest. Meta-analysis was performed using a random-effects model where appropriate. The standardized mean difference of changes from baseline to follow-up between treatment groups was determined. Recommendations were made using Grades of Recommendation Assessment, Development, and Evaluation criteria. Results. We identified 12 studies, including 7 randomized controlled trials, 4 cohort studies, and 1 case-control study that evaluated kinematic measurements at the adjacent segments or the global cervical spine (C2-C7) after cervical arthroplasty compared with ACDF. We found no statistically significant differences between treatment groups in the change in range of motion (ROM) at the cranial or caudal adjacent segments from baseline to 2 years of follow-up. However, there was low evidence that the global cervical spine (C2-C7) had significantly greater change in ROM after arthroplasty compared with ACDF: patients had a greater angular ROM as measured up to 2 years after arthroplasty. We found no statistically significant differences between treatment groups in the change in the horizontal or vertical centers of rotation at the adjacent segments as measured up to 2 years after surgery. Regarding sagittal alignment, the cranial and caudal adjacent segments both became significantly more lordotic after arthroplasty compared with fusion at 1 to 2 years after surgery. However, there was no statistically significant difference between treatment groups in the change in global cervical sagittal alignment from baseline to 2 years. Conclusion. There is no statistically or clinically significant difference in the adjacent segment ROM or centers of rotation after cervical arthroplasty compared with ACDF. However, the change in sagittal alignment at the cranial and caudal adjacent segments was significantly more lordotic after arthroplasty compared with fusion. In addition, although we found that there was no statistically significant difference between treatment groups in the change in global cervical (C2-C7) sagittal alignment, there was a significantly greater change in the angular ROM of the cervical spine at up to 2 years after arthroplasty than occurred after fusion. Consensus Statement: Patients can be advised that single-level arthroplasty and ACDF result in clinically similar kinematic changes at short-term follow-up.Strength of Statement: Strong. Copyright © 2012 Lippincott Williams & Wilkins.
Duggal N.,London Health Sciences Center |
Bertagnoli R.,Spine Center |
Rabin D.,London Health Sciences Center |
Wharton N.,Medical Metrics Inc. |
Kowalczyk I.,London Health Sciences Center
Journal of Spinal Disorders and Techniques | Year: 2011
STUDY DESIGN: A prospective study of 22 patients with single-level cervical spondylosis. OBJECTIVE: To quantify the changes in the biomechanics of the cervical spine after the insertion of a ProDisc-C (Synthes Spine, Paoli, PA) artificial disc. SUMMARY OF BACKGROUND DATA: Cervical arthroplasty is designed to maintain cervical motion of the functional spinal unit (FSU) after cervical discectomy. The impact of the ProDisc-C on in vivo kinematics and sagittal alignment requires further assessment. METHODS: Flexion/extension lateral radiographs of the cervical spine were prospectively collected and reviewed in 22 patients preoperatively and after the placement of ProDisc-C. Disc height (DH), FSU angle, range of motion (ROM), and center of rotation (COR) were calculated at each time point using validated, computer-assisted methods. Preoperative values were compared with the postoperative values using paired student t tests. RESULTS: Mean follow-up time was 11.0 months (SD, 2.4 mo). At the surgical level, the ProDisc-C produced increased segmental ROM (P=0.03), an anterior shift of 1.1 mm in COR X (P=0.004), and increased DH both anteriorly (P<0.0001) and posteriorly (P<0.0001). At the inferior adjacent level, anterior DH decreased (P<0.05) and posterior DH increased (P=0.02) after surgery. The FSU angle at the surgical level increased (P<0.0001), but the inferior adjacent-level FSU angle decreased (P=0.002). No significant changes were observed at the superior adjacent level. CONCLUSIONS: The ProDisc-C increased segmental ROM and shifted the COR anteriorly at the surgical level. DH increased at the surgical level. The surgical level became more lordotic, whereas the inferior adjacent level became more kyphotic after ProDisc-C implantation. Copyright © 2011 by Lippincott Williams & Wilkins.
Medical Metrics Inc. | Date: 2011-02-14
Computer software for providing enhanced visualization, interpretation, and detection of differences between medical images.
Medical Metrics Inc | Date: 2010-03-02
Computer software for measuring relative motion between anatomic structures in human and animal bodies, and for measuring motion of structures over time, as visualized in medical and other images.
Trautwein F.T.,Paradigm Spine |
Lowery G.L.,Paradigm Spine |
Wharton N.D.,Medical Metrics Inc. |
Hipp J.A.,Medical Metrics Inc. |
Chomiak R.J.,Paradigm Spine
Spine Journal | Year: 2010
Background context: The in vivo loading environment of load-bearing implants is generally largely unknown. Loads are typically approximated from cadaver tests or biomechanical calculations for the preclinical assessment of a device's safety and efficacy. Purpose: To determine the actual in vivo loading environment of an elastic interlaminar-interspinous implant (Coflex). Study design: A retrospective radiographic study to noninvasively measure the in vivo implant loads of 176 patients. Methods: For this study, neutral, flexion, and extension radiographs were quantitatively analyzed using validated image analysis technology. The angle between the Coflex arms was measured for each radiograph and statistically evaluated. Separately, the Coflex implant was characterized using mechanical test data and finite element analysis, which resulted in a load-deformation formula that describes the implant load as a function of its size and elastic deformation. Using the formula and the elastic implant deformation data obtained from the radiographic analysis, the exact implant load was calculated for each patient and each posture. For statistical analysis, the patients were grouped by indication and procedure, which resulted in 12 different groups. The determined loads were compared with the strength of the posterior lumbar spinal elements obtained from the literature and with the static and dynamic mechanical limits of the Coflex interlaminar-interspinous implant. Results: The force data were independent of implant size, diagnosis (with one exception), number of levels of the decompression procedure, number of levels of implantations (one or two), and follow-up time. The median compressive force acting on the Coflex implant was found to be 45.8 N. The maximum load change between flexion and extension was 140 N; the maximum overall load exceeded 239 N in extension. Conclusions: The average loads exerted by the Coflex implant on the spinous process and lamina are 11.3% and 7.0% of their respective static failure load. The implant fatigue strength is significantly higher than the measured median force, which explains the extremely rare observation of a Coflex fatigue failure. © 2010 Elsevier Inc. All rights reserved.
Medical Metrics Inc. | Date: 2016-01-14
The present disclosure describes a method for determining spinal instability, more particularly, a method for quantifying the type and extent of spinal instability in a standardized way. The disclosure also describes a method comprising measurement of the intervertebral rotation and intervertebral translation between a vertebrae pair using simple images, and from these measurements, determining if one or more vertebrae pair of the spine is unstable. Finally, the disclosure describes software that may be used to quantify the type and extent of spinal instability.