227 research outputs found
Quantitative evaluation of facet deflection, stiffness, strain and failure load during simulated cervical spine trauma
No full textAbstract not availableRyan D. Quarrington, John J. Costi, Brian J.C. Freeman, Claire F. Jone
Ankylosing spondylolitis and epilepsy: A dangerous combination
No full textCopyright © 2009 Elsevier Ltd All rights reserved.David W. Ardern, Y.H. Yau and Brian J.C. Freema
ISSLS Prize Winner: Cost-effectiveness of two forms of circumferential lumbar fusion: A prospective randomized controlled trial
No full textStudy Design. Economic evaluation alongside a prospective, randomized controlled trial from a secondary care National Health Service (NHS) perspective. Objective. To determine the cost-effectiveness of titanium cages (TC) compared with femoral ring allografts (FRA) in circumferential lumbar spinal fusion. Summary of Background Data. A randomized controlled trial has shown the use of TC to be clinically inferior to the established practice of using FRA in circumferential lumbar fusion. Health economic evaluation is urgently needed to justify the continued use of TC, given that this treatment is less effective and, all things being equal, is assumed more costly than FRA. Methods. Eighty-three patients were randomly allocated to receive either the TC or FRA as part of a circumferential lumbar fusion between 1998 and 2002. NHS costs related to the surgery and revision surgery needed during the trial period were monitored and adjusted to the base year (2005–2006 Pounds Sterling). The Short Form-6D (SF-6D) was administered before surgery and at 6, 12 and 24 months in order to elicit patient utility and subsequently Quality-Adjusted Life Years (QALYs) for the trial period. Return to paid employment was also monitored. Bootstrapped mean differences in discounted costs and benefits were generated in order to explore cost-effectiveness. Results. A significant cost difference of £1950 (95% CI, £849 to £3145) in favor of FRA was found. Mean QALYs per patient over the 24-month trial period were 0.0522 (SD, 0.0326) in the TC group and 0.1914 (SD, 0.0398) in the FRA group, producing a significant difference of −0.1392 (95% CI, −0.2349 to −0.0436). With regard to employment, incremental productivity costs were estimated at £185,171 in favor of FRA. Conclusion. From an NHS perspective, the trial data show that TC is not cost-effective in circumferential lumbar fusion. The use of FRA was both cheaper and generated greater QALY gains. In addition, FRA patients reported a greater return to work rate
Detecting facet joint and lateral mass injuries of the subaxial cervical Spine in major trauma patients
No full textStudy Design: Radiologic imaging measurement study. Purpose: To assess the accuracy of detecting lateral mass and facet joint injuries of the subaxial cervical spine on plain radiographs using computed tomography (CT) scan images as a reference standard; and the integrity of morphological landmarks of the lateral mass and facet joints of the subaxial cervical spine. Overview of Literature: Injuries of lateral mass and facet joints potentially lead to an unstable subaxial cervical spine and concomitant neurological sequelae. However, no study has evaluated the accuracy of detecting specific facet joint injuries. Methods: Eight spinal surgeons scored four sets of the same, randomly re-ordered, 30 cases with and without facet joint injuries of the subaxial cervical spine. Two surveys included conventional plain radiographs series (test) and another two surveys included CT scan images (reference). Facet joint injury characteristics were assessed for accuracy and reliability. Raw agreement, Fleiss kappa, Cohen's kappa and intraclass correlation coefficient statistics were used for reliability analysis. Majority rules were used for accuracy analysis. Results: Of the 21 facet joint injuries discerned on CT scan images, 10 were detected in both plain radiograph surveys (sensitivity, 0.48; 95% confidence interval [CI], 0.26-0.70). There were no false positive facet joint injuries in either of the first two X-ray surveys (specificity, 1.0; 95% CI, 0.63-1.0). Five of the 11 cases with missed injuries had an injury below the lowest visible articulating level on radiographs. CT scan images resulted in superior inter- and intra-rater agreement values for assessing morphologic injury characteristics of facet joint injuries. Conclusions: Plain radiographs are not accurate, nor reliable for the assessment of facet joint injuries of the subaxial cervical spine. CT scans offer reliable diagnostic information required for the detection and treatment planning of facet joint injuries.Joost Johannes van Middendorp, Ian Cheung, Kristian Dalzell, Hamish Deverall, Brian J.C. Freeman, Stephen A.C. Morris, Simon J.I. Sandler, Richard Williams, Y.H. Yau, Ben Gos
Biofilm formation by Propionibacterium acnes on biomaterials in vitro and in vivo: Impact on diagnosis and treatment
No full textPublished in Journal of Biomedical Materials Research Part A, 2007; 81A (3):705-709 at www.interscience.wiley.comPropionibacterium acnes is found increasingly as a cause of delayed infection, usually involving implanted biomaterials. Despite susceptibility to common antibiotics, such infections are very difficult to treat and usually require surgical removal of the device. Three clinical isolates of P. acnes were assessed for ability to adhere to titanium, surgical steel and silicone, with and without a plasma conditioning film. After adherence, the biomaterials were then incubated for a further 6 days and examined for biofilm development. All three isolates adhered to all three biomaterials similarly. Importantly, we were able to demonstrate biofilm formation, including production of exopolymer similar in appearance to the polysaccharide intercellular adhesin of Staphylococcus epidermidis. A case summary also demonstrated failure to eradicate P. acnes infection in a hydrocephalus shunt after prolonged treatment. The removed shunt showed obvious biofilm formation, initially obscured by exopolymer when viewed by environmental scanning electron microscopy. Biofilm development by P. acnes explains the difficulties encountered in clinical management of such infections.Roger Bayston, Waheed Ashraf, Robert Barker-Davies, Emily Tucker, Rhys Clement, Juliet Clayton, Brian J.C. Freeman and Bryar Nuradee
Axon stretch growth: towards functional repair of the spinal cord: a translational exercise
No full textBackground:
Injury to the spinal cord often visually presents as a local injury, damaging neurons that reside in the spinal cord, their projecting axons and supporting infrastructure such as oligodendrocytes. However, damage also occurs to ascending and descending axons that communicate with the brain. Fundamentally, repair of these injuries requires two distinct restorative approaches. The local injury will require stabilisation of the local environment, the rescue of injured neurons and support infrastructure, replacement of lost cells and restoration of intra-spinal communication. The latter ascending and descending axon injury will require proximal and distal axon reunification to restore supra-spinal communication with the brain.
This thesis presents the results of an early translational exercise that takes a non-linear approach to facilitate investigation into axon stretch growth (ASG) - an intrinsic mechanism that allows axons to adapt to body height and size throughout life. Pioneering research has shown that in-vitro exploitation of ASG has the potential to bridge significant gaps associated with injuries to long supra-spinal nerve tracts within the spinal cord.
Although translational science can be applied across the research spectrum, the traditional practice is to intervene once the research has matured. Here, the intervention occurs early, in an environment of limited funding within a progressive school of basic sciences. At the time of intervention, no infrastructure or experience in ASG research was evident within the faculties.
Translational Methods:
The absence of a robust in-vitro adult motor neuron culture was identified as a potential barrier in ASG translation. Collaborations in anatomy, neuroscience, and toxicology were formed. Three separate animal ethics applications were required. Publication of a protocol followed.
The infrastructure required to conduct necessary in-vitro investigations into ASG was determined. Multidisciplinary collaborations were formed with mechanical, electrical and electronics engineers. Design, engineering, and commissioning of the equipment followed.
The lack of a definitive translational animal model has been previously identified as a significant barrier to spinal cord injury research. Specifically, a suitable large animal model has yet to be clearly defined for ASG research. Collaborations with comparative anatomy, a large animal research centre, and a senior spinal surgeon progressed development of a sheep model. Separate multi-institutional animal ethics applications were also required.
Results:
A robust peer reviewed method was established to hydraulically extrude the spinal cord of adult Sprague-Dawley rats in under 60 seconds, and a serum free culture protocol simplified to maximise the yield of motor neurons and reduce culture costs. Adult motor neurons harvested and cultured using this protocol are capable of in-vitro survival for periods exceeding 21 days.
A decommissioned infant humidicrib was successfully converted into a portable temperature (32 – 39°C ± 0.1°C), and carbon dioxide controlled imaging incubator. Additional modifications incorporating umbilical support for multiple tailored bioreactors was also developed. A tailored ASG bioreactor was prototyped, tested, and commissioned. Axon stretch growth of motor neurons has been initiated in the bioreactor.
The literature review suggested that non-human primates were the optimal model for final translational confirmation. However, there was sufficient evidence to indicate that ungulates (i.e. sheep or pig) may be an alternative for ASG research. Relevant information on the sheep was collated, and basic investigation on their anatomy progressed.
Conclusion: Early applied translational science (as practised here) is strategic and cost effective, showing that the overall strategy facilitates research, while potentially identifying barriers that could delay progress or cause late translational failure. The introduction of an “off the shelf” early intervention funding model allocated to translational scientists should be considered as a mechanism to progress basic science investigations that are in conceptual stages of development.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, Adelaide Medical School, 201
To compare radio-stereometric analysis (RSA) and computed tomography (CT) for the assessment of lumbar spinal fusion in a sheep model.
No full textStudy design: A comparison of Radio-Stereometric Analysis (RSA) and Computed Tomography (CT) for the assessment spinal fusion in a large animal model. Introduction and Aims: Anterior Lumbar Interbody Fusion (ALIF) is a surgical procedure that is commonly performed for patients with chronic disabling low back pain that is unresponsive to conservative treatments. CT is a standard technique to assess the completeness of fusion but has a high radiation penalty to the patient. RSA is an alternative method to assess fusion with a much lower radiation exposure for the patient and is reported to have high accuracy. The study compares RSA to fine-cut CT scan using histology from necropsy specimens as the reference standard. Methods: Three non-adjacent ALIFs (L1-L2, L3-L4, and L5-L6) were carried out in 9 sheep. The sheep were divided into three groups of 3 sheep. The first group had RSA immediately post-op, 3 and 6 months after surgery. The second group had RSA immediately post-op, 3, 6 and 9 months after surgery. The third group had RSA immediately post-op, 3, 6, 9 and 12 months after surgery. All the animals were humanly killed immediately after having the last scheduled RSA. The lumbar spine was removed and invitro fine cut CT and histopathology were performed. The RSA was carried out by an experienced scientist to determine the number of fused levels. Post-mortem CT scans were performed and reviewed by up to three radiologists to assess the number of fused levels. Histology sections were taken throught the ALIF segments and reviewed by a senior research scientist with expertise in histology and a consultant pathologist. Results: Using histological assessment as the gold standard for assessing fusion, RSA demonstrated superior results (100% sensitivity and 66.7% specificity (PPV = 27.3%, NPV =100.0%) when compared to CT (66.7% sensitivity and 60.0% specificity (PPV = 16.7%, NPV = 93.8%). The assessment of the inter-rater reliability of the first CT scan of the two radiologists indicated no agreement (k = 0.07, p-value = 0.353). As indicated in the methods section, when a discrepancy occurred, a 3rd independent radiologist assessed the CT scans, with this review providing the final CT scan result. The Fleiss Kappa statistic indicated no agreement between the 1st and 3rd radiologist (k = 0.10, p-value = 0.333) on the occasions where the results of the 3rd radiologist were known (n=12 of the 27 results). The Fleiss Kappa statistic between the 2nd and 3rd radiologist also indicated no agreement (k = -0.13, p-value = 0.668). Significant inter-observer error was observed amongst radiologists using CT Scans for the assessment of fusion. Conclusion: Using histological assessment as the gold standard for the assessment of fusion in this animal model, RSA demonstrated higher sensitivity and specificity when compared to CT. Furthermore RSA has the advantage of much lower radiation exposure compared to fine cut CT. Further studies are required to see if RSA remains superior to CT scan for the assessment spinal fusion in the clinical setting.Thesis (M.S.) -- University of Adelaide, School of Medicine, 201
Real-time Multi-ring Differential Chain Coding
No full textFor the encoding of line drawing graphics for transmission and storage, chain coding has proven to be an effective scheme. This coding technique, introduced by H. Freeman, is based upon a vector representation of the drawing. This technique has been further examined at Delft University of Technology, where new types of chain coding have been developed, known as Differential Chain Coding (DCC) and Multi-ring Differential Chain Coding (MRDCC). An investigation for real-time application of MRDCC, which is called RT-MRDCC, is done. The performance results presented, establish RT-MRDCC as an efficient alternative for the encoding of line drawing.Applied SciencesElectrotechniekTelecommunicatie- en Verkeersbegeleidingssysteme
The effect of axial compression and distraction on cervical facet mechanics during anterior shear, flexion, axial rotation, and lateral bending motions
No full textThe subaxial cervical facets are important load-bearing structures, yet little is known about their mechanical response during physiological or traumatic intervertebral motion. Facet loading likely increases when intervertebral motions are superimposed with axial compression forces, increasing the risk of facet fracture. The aim of this study was to measure the mechanical response of the facets when intervertebral axial compression or distraction is superimposed on constrained, non-destructive shear, bending and rotation motions. Twelve C6/C7 motion segments (70 ± 13 yr, nine male) were subjected to constrained quasi-static anterior shear (1 mm), axial rotation (4°), flexion (10°), and lateral bending (5°) motions. Each motion was superimposed with three axial conditions: (1) 50 N compression; (2) 300 N compression (simulating neck muscle contraction); and, (3) 2.5 mm distraction. Angular deflections, and principal and shear surface strains, of the bilateral C6 inferior facets were calculated from motion-capture data and rosette strain gauges, respectively. Linear mixed-effects models (α = 0.05) assessed the effect of axial condition. Minimum principal and maximum shear strains were largest in the compressed condition for all motions except for maximum principal strains during axial rotation. For right axial rotation, maximum principal strains were larger for the contralateral facets, and minimum principal strains were larger for the left facets, regardless of axial condition. Sagittal deflections were largest in the compressed conditions during anterior shear and lateral bending motions, when adjusted for facet side.Ryan D. Quarrington, John J. Costi, Brian J.C. Freeman, Claire F. Jone
J.C. Bach's London keyboard sonatas : style and context
No full textJ. C. Bach's keyboard works include several sets of accompanied sonatas, a genre that enjoyed a wide popularity during the Classical era, but never
found its way into the concert repertoire. The accompanied sonata was a genre meant for domestic performance; the solo keyboard sonata, on
the other hand, was adopted in due course by concert audiences. J. C. Bach composed works within both genres during most of his productive years, and his output constitutes a corpus of remarkable consistency. J. C. Bach's removal to London in 1762 coincided with his clear adoption of a galant style, marked by the Italianate influence, and the abandonment of most Baroque traits. The British milieu provided additional factors: the rise of the pianoforte, a thriving music-publishing market, and a great interest in domestic music making among the affluent classes. These factors marked J. C. Bach's output at various levels. Keyboard works had to conform to the proficiency of the amateur performer, a
fact reflected in the accompanied output mostly. The number of movements, their length, and the inclusion of particular technical devices are readily observable differences between the two genres. The most remarkable
distinction lies perhaps in the preference for binary sonata format in the accompanied. sonatas from the mid 1760s to the 1770s, in spite of a later tendency for tripartite designs in both genres. J. C. Bach's lifelong preference for motivic phrase structure conditioned his keyboard production and partly explains the gap in quality between some of his works and sonatas composed around the same time by Haydn and Mozart, who developed more effective means to connect the melodic material
to higher structural units. J. C. Bach's influence, however, endured in Mozart's handling of melody, and his keyboard production constitutes, in spite of some flaws, a noteworthy example of elegance and craftsmanship
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