1,721,002 research outputs found
The present day potential role of fractional flow reserve-guided coronary artery bypass graft surgery
No full textThe favorable impact of fractional flow reserve measurements on the decision-making and overall outcomes of percutaneous coronary artery intervention is well established. However, the clinical application of fractional flow reserve in surgical revascularizations is still debated. The purpose of this article is to provide a comprehensive review on the current potential role of fractional flow reserve guidance in coronary artery bypass grafting
Determining pull-out strength for screws engaging posterior cortex, compared to screws placed into the tibia metaphysis for medial malleolus ankle fractures. A comparative cadaver model
No full textAim: Failure of fixation of an ankle fracture is common in bone of poor quality. Improving the strength of fixation could lead to better results.
The aim of this study is to evaluate if the pullout strength of a medial malleolus screw can be increased if it is inserted in such a way that the screw engages the posterior metaphyseal cortex of the tibia.
Method: Comparative study on 13 cadavers, fixing a medial malleolus osteotomy with a 4.0mm partial threaded cancellous screw. The right ankle of each cadaver was fixed with a screw engaging the posterior metaphysical cortex, the left ankle was fixed with a screw only engaging the trabecular metaphyseal bone. Axial traction was applied to the screw until failure of fixation occurred. Failure being defined as 2mm distraction over the fracture site. Axial traction was applied with a traction scale calibrated in kilograms.
Results: In all ankle osteotomies an anatomic reduction was achieved. The mean strength was 87.66N for metaphysical purchase screws, compared to 208.88N for cortical Purchase screws. (p-value 0.002). For screws inserted not engaging the posterior cortex of the tibia, the lowest recorded pullout strength was 15.69N. The maximum recorded pullout strength, for a screw not engaging the cortex, was 181.42N. For screws engaging the posterior tibia cortex the minimum recorded pullout strength was 72.57N and the maximum recorded 414.82N.
Conclusion: The results show a significant improvement in the pullout strength of medial malleolus screws inserted to engage the posterior tibia cortex
Using a condom to prevent cement interdigitation into bone during the first stage of a two-stage revision arthroplasty for a periprosthetic joint infection
No full textIntroduction and Aims: Total joint replacements are a universally accepted treatment in patients with end-stage osteoarthritis, post-traumatic arthritis, inflammatory arthritis, avascular necrosis of the femoral head as well as developmental dysplasia.1,2 Due to an ageing population the demand for these procedures are increasing. On the other hand complications associated with arthroplasty will also increase. It can be argued that the most devastating complication following arthroplasty is infection. Prosthetic infections are difficult to treat and usually requires revision surgery. Whether the revision is done in a single stage or as a two-staged procedure, it remains a challenge to remove the infected prosthesis and replace it with a temporary antibiotic spacer. If the spacer is inserted as for a primary or uninfected revision replacement, interdigitation of the cement into the interstitial spaces of the bone occurs. In non-infected primary or revision surgery this is desirable as this strengthens the bone-cement-interface resulting in a stable prosthesis. Once an implant becomes infected and a two-stage revision is planned, the very same strong bone-cement interface presents a serious problem. Removal of these infected implants can be very time-consuming. If one can prevent interdigitation of the cement at the time of insertion of the temporary cement spacer, it may significantly shorten the second stage of the procedure and possibly prevent complications. The purpose of this study is to determine if the interdigitation of bone cement into bone can be prevented by using a standard, government issued male or female condom during the first stage of a two-staged revision procedure. Methodology: The study was conducted in the dissection hall of the Department of Anatomy of the Faculty of Health Sciences at the University of the Free State. Eleven cadavers were available at the time of conducting the study. Standard government issued male and female condoms were used. A cross-sectional study design was used and the data was analysed by the Department of Biostatistics at the University of the Free State. Results: Twenty-one femurs and thirteen tibias were used. In the femur, we used a male condom in eleven cases and a female condom in ten cases. The condom was intact in one case and ruptured in ten cases when a male condom was used in the femur. No interdigitation of cement was seen during visual inspection in any of these cases. When a female condom was used it was intact in seven cases and not intact in three cases and no interdigitation was also noted in any of the cases. In the tibia we used a male condom in eleven and a female condom in two cases. The male condom was intact in eight cases and it ruptured in three cases with no interdigitation of cement noted. A female condom was used in only two cases and was intact in both of these with no interdigitation of cement on visual inspection. Without exception all the condoms, male and female, ruptured at the distal end covering the tip of the prosthesis whilst the part of the condom surrounding the prosthesis proximal to tip were intact and therefore prevented interdigitation of the cement. Although interdigitation was not observed in any of the cadavers, we found a statistical significant difference between intact male and female condoms when used in the femur (P = 0.05). There was however a statistical significant difference when the intact condoms used in the tibia were compared to the intact condoms in the femur (P < 0.05). Conclusion: Our findings suggest that either a male or a female condom may be used to prevent interdigitation of cement into the trabecular bone. Using a standard government issued female condom is easier and more reliable when compared to using a standard government issued male condom. The utilization of a condom in the femur proved to be troublesome due to various reasons. Our study furthermore indicates that it is better to use a female condom in the femur. No cement interdigitation was noted upon inspection regardless of the condom used. Recommendations: We recommend that a standard government issued female condom may be used to prevent the interdigitation of cement into the trabecular bone in both the proximal femur and proximal tibia. The use of a male condom should be reserved for use in the tibia. Despite our findings in cadaveric models, further in vivo research is necessary before the technique can be advocated as safe to use in patients. Another study investigating the sterility of the condoms that were used are currently being undertaken at the UFS
Determining the rotational strength of Lateral Malleolus Locking Plate versus Fibula Intramedullary nail in Supination External Rotation type IV injuries: cadaveric study
No full textIntroduction: Open reduction and internal fixation (ORIF) with anatomical reduction of
displaced ankle fractures have been the standard of care since the 1960, but are associated
with increased risk of complication, especially wound dehiscence and infections. Studies
showed that minimal invasive ankle fracture fixation with a fibula intramedullary nail can reduce
these complications with good clinical results after fracture fixation. Biomechanical evidence of
its strength compared with locking plates and screws, is currently limited.
Aims: We examined the biomechanical properties of a distal fibular locking plate with the fibula
intramedullary nail for fixation of ankle fractures induced in cadaveric models. Methods: 14
cadavers (28 limbs) were used and supination external rotation (SER) IV injury was surgically
created. Right limbs was allocated to the locking plate group and left limbs to the intramedullary
fibula nail group. Biomechanical testing was performed simulating an external rotation force.
Results: There was no statistical difference between the mean force needed for loss of
anatomical reduction in the locking plate group and fibula nail group. There was, however, a
statistical difference between the mean forces for total implant failure between the locking plate
group and fibula nail group.
Conclusion: This cadaver study supports previous biomechanical research findings of
comparable stability between the two surgical techniques when looking at the force needed to
cause loss of anatomical reduction. The locking plates, was however superior to the fibula nail with regards to the amount of force needed to cause implant failure. From a biomechanical
perspective, this showed that the fibula nail is be a viable option when treating unstable fibula
fractures
Investigating the possibility of using groundwater associated with dolerite structures to augment the municipal water supply to the city of Bloemfontein: investigations in the central business district
No full textThis study investigates the potential of using groundwater resources associated with an intrusive
dolerite ring-dyke underlying the central business district (CBD) of Bloemfontein to augment the
current water supply to the Mangaung Metro Municipality (MMM). The current water supply to the
municipality is wholly dependent on surface water sources, which have proved to be unreliable and
insufficient to meet the increasing water demand in the municipality.
During the investigations, ground geophysical methods were used to detect and delineate the ringdyke
in areas within the CBD where the surface infrastructure allowed the geophysical surveys. The
magnetic and electrical resistivity (ERT) methods were used during the surveys. The magnetic
method is sensitive to both the presence of metallic infrastructure at surface or in the shallow
subsurface and to the presence of electromagnetic noise generated where electrical currents flow.
Since urban and industrial environments are characterised by such sources of noise, the magnetic
survey was severely restricted in terms of the locations available for the recording of reliable data.
The ERT survey, in turn, was severely restricted in terms of the space available within the CBD, as
well as the presence of hard surface covering (roads, pavements, concrete slabs) prohibiting the
installation of electrodes into the ground. Despite these limitations, the geophysical surveys were
successful in detecting the presence of the ring-dyke at certain positions within the CBD.
Based on the results of the geophysical investigations, positions for the drilling of investigative and
production boreholes were proposed. The drilling of these boreholes was to form part of the current
investigations, but due to factors beyond the control of the researcher, these boreholes are yet to be
drilled. These boreholes would have allowed the researcher access to the aquifers system associated
with the ring-dyke in order to perform hydraulic tests and assess the groundwater quality. The fact
that these boreholes were not drilled in time should be seen as a significant limitation of the current
study.
A limited hydrocensus was conducted in the vicinity of the ring-dyke. The purpose of the hydrocensus
was to locate points of groundwater abstraction near the ring-dyke in order to obtain information on
the use and quality of the groundwater, as well as to investigate the aquifer system(s) hosting the
groundwater. During the hydrocensus, several boreholes were located within 300 m from the ringdyke.
Of these boreholes, access to only three could be obtained as the owner of the properties on
which the remaining boreholes were located would not allow access to these boreholes. The
hydrocensus revealed that the boreholes near the ring-dyke are currently mostly used for irrigation.
No hydraulic tests could be performed on the boreholes identified during the hydrocensus due to the
presence of infrastructure. Hydraulic tests were, however, performed on a single borehole located on the premises of the Central University of Technology (CUT). Analyses of the results of the hydraulic
tests indicated transmissivity values in the order of hundreds of metres squared per day, indicating
that the aquifer system associated with the ring-dyke can be expected to be high-yielding.
Hydrochemical analyses of the groundwater samples collected from the boreholes identified during
the hydrocensus showed that the groundwater quality ranges from good to ideal. No clear evidence
for contamination was visible in the results of the inorganic analyses. The good quality of the
groundwater suggests that it can be incorporated into the municipal water supply without requiring
too much treatment. However, the investigations into the groundwater quality did not consider
hydrocarbon or bacteriological contamination of the groundwater. No conclusions can therefore be
drawn on the groundwater quality in terms of possible organic and bacteriological contaminants.
The results of the investigations indicate that that groundwater associated with the ring-dyke could
successfully be used to augment the municipal water supply. Depending on the quality of the
groundwater, it may find different applications in the municipality, including: domestic water,
irrigation, and industrial use. However, each of these applications has its own challenges in terms of
monitoring, aquifer management, water treatment and infrastructural requirements. To ensure the safe
and sustainable use of the groundwater resource, a groundwater monitoring and management
programme should be implemented. Such a programme will aim to ensure that the volumes of
groundwater abstracted do not exceed the long-term capacity of the aquifer system to deliver water,
while ensuring that the quality of the water delivered to the municipal supply system is of a suitable
quality for the its intended purpose. Routine monitoring of the water quality should be done to detect
possible contamination with organic compounds and bacteria, as well as industry-specific
contaminants
Condom sterility in periprosthetic joint infection management at Universitas academic hospital in Bloemfontein 2018
No full textJoint replacement surgery, especially of the hip and knee, is one of the most rewarding operations for both the patient and the orthopaedic surgeon worldwide. Hip replacement has been dubbed the operation of the century. This is because these replacements improve the quality of life for the elderly population crippled with arthritis, and in recent years, due to better implants, also improves quality of life in the younger generation presenting with joint problems. It is, however, not without complications, the most important being periprosthetic joint infections. Other complications include aseptic loosening, periprosthetic fractures and dislocation. Periprosthetic joint infection is the most dreaded of the complications because of its difficulty to manage and association with significant morbidity and bone loss. We therefore began by describing and defining periprosthetic joint infection and investigated the current epidemiological data available. We have reviewed literature and looked at the diagnostic criteria from the different societies and meetings from around the world. Parvizi et al. developed an algorithm and proposed criteria that are based on the latest data and tests. This is explained in detail in the first chapter of this dissertation. The management of periprosthetic joint infection is dependent on the amount of time from the index joint surgery. An outline of the deferent management options are presented, while bearing in mind that two-stage revision surgery is the gold standard of management. Management of periprosthetic joint infection is associated with bone loss, either with the removal of infected implants or removal of the cement spacer in the second surgery of the twostage procedure. A recent unpublished study done locally in our department showed that putting a cement spacer in a condom and then placing the condom-cement spacer in the joint to allow it to set, and then taking out the condom-cement spacer after the cement had set, was associated with no bone loss. The study also showed that female condoms were stronger and more durable compared to the male condoms. The question that needed to be addressed, was whether it is safe to introduce condoms into the joint? Based on the literature, there is a 10% chance that condoms maybe contaminated. We investigated the sterility of condoms from the packaging and how to improve the sterility of the condoms. Sixty government-issued female condoms were used for the study, of which 30 were tested straight from the packaging and the other 30 were first put through hydrogen peroxide gas plasma sterilisation and then tested by means of MC&S. Similar to previously published studies, contamination of the condoms was confirmed, although in our study, the rate of contamination was 60%. We also isolated nonvirulent environmental and implant contaminants. The most important aspect of the results was that we were able to achieve 100% sterility of the condoms with hydrogen peroxide gas plasma. This was significant because we can place condoms for its intended use in the joints without introducing further infection in the joint. Once sterilised, condoms can also be used for other sterile/aseptic medical procedures, such as ultrasound probe covering and temperature probe covers
SI screw vs locking square plate fixation in sacroiliac joint disruption on composite bone models
No full textBackground: The aim of this study was to compare a locked square plate to a standard sacroiliac screw of the sacroiliac joint on a composite pelvis bone model to assess the ultimate load tolerated before failure of fixation and to describe the mode of failure of the construct. Methods: Bilateral sacroiliac (SI) joint dislocations were created in 10 composite pelvic bone models. In this descriptive comparative study, the one SI joint was fixated using a 7.3mm cannulated screw and the contralateral side fixated using a 4-hole square locking plate. The pubic symphysis was not fixed. An upward vertical load was manually applied to each respective SI joint using a hook into the sciatic notch. The ultimate load to failure and the mode of failure was recorded for both groups. Results: The mean load to failure for the SI screw group was 310 N and for the SI plate group 580 N. The ultimate load to failure was significantly lower in the SI screw group (p=0.0002). There were no hardware-related failures recorded in any of the fixations in the study. The SI screw group had failure through a fracture of the sacrum in all the specimens. In the SI plate group, fractures of the sacrum and ilium constituted, respectively, 60% and 40%. Conclusion: A locked square plate fixation is superior to a single SI screw at the ultimate load to failure when a vertical load is applied to the sacroiliac joint in a composite bone model
Continued development of a joint-type knee wear simulator
Full text linkThesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: This thesis is concerned with the continued development of the Stellenbosch
University joint-type knee wear simulator. Initially, information regarding simulators
from the literature and commercial entities was collected to provide a
knowledge base for current and future work. To further the design of the
simulator itself, electronic hardware and software subsystems was developed
and evaluated during experimental testing procedures. National Instruments’
cDAQ 9174 data acquisition unit was deemed inadequate for real-time inputoutput
control, though proved sufficient for signal capturing purposes in conjunction
with LabView software. Furthermore, the various servo-pneumatic
sub-circuits’ individual ability to conform to the ISO 14243 series standards’
protocol led to the estimation of measurable performance criteria and the application
to a single circuit for illustration. The anterior/posterior actuation
circuit in question demonstrated adequate performance for the cases where the
piston’s rod was respectively fixed and free to move. In-silico modelling and
identification of the relevant servo-pneumatic components then commenced,
with the valve and cylinder chamber models yielding adequate estimates of
the recorded data. The identified quasi-static friction model proved sensitive
to transient effects present within the system, resulting in performance deterioration
of the integrated model. Sufficiently accounting for these effects would
result in the emergence of the sub-circuit’s model as an invaluable tool in
terms of control system development, prediction of the simulator’s behaviour
and subsequent design recommendations. Future work therefore concerns improvement,
identification and integration of the various sub-circuit models to
fully exploit the aforementioned advantages.AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die voortgesette ontwikkeling van Universiteit Stellenbosch
se gewrigstipe knie-afslytingsimulator. Aanvanklik is inligting versamel
vanaf literatuur en kommersiële entiteite om sodoende ’n kennisbasis te
verskaf vir huidige en toekomstige werk. Elektroniese hardeware en sagteware
stelsels is ontwerp en geëvalueer tydens toetsprosedures om die ontwerp van die
simuleerder self te verbeter. National Instruments se cDAQ 9174 dataversamelaarseenheid
word onvoldoende geag vir intydse inset-uitset beheer, maar wel
vir dataversamelingsdoeleindes tesame met LabView sagteware. Die nodigheid
om die verskeie servo-pneumatiese sub-stroombane se individuele vermoë
om aan te pas by die ISO 14243-reeks se protokol-standaarde te ondersoek,
het gelei tot die beraming van meetbare werkverrigtingskriteria en die toepassing
daarvan ter illustrasie. Die anterior/posterior stroombaan het voldoende
werksverrigting getoon vir studies waar die suier se stang onderskeidelik vas
en los was. In-silico modellering en die identifisering van servo-pneumatiese
komponente het hierna begin. Die klep en silinderkamer modelle het voldoende
skattings gelewer van die gemete data. Die geïdentifiseerde kwasistatiese wrywingsmodel
het sensitiwiteit getoon teenoor die oorgangseffekte teenwoordig in
die stelsel wat gelei het tot verminderde werksverrigting van die geïntegreerde
model. Deur rekening te hou met sulke effekte kan die sub-stelsel se model
waardevol wees sover dit beheerstelsel ontwikkeling aangaan, sowel as die
voorspelling van die simuleerder se optrede en die daaropvolgende ontwerpsvoorstelle.
Toekomstige navorsing kan fokus op die verbetering, identifikasie
en integrasie van die verskeie sub-stroombaan modelle om die voorafgenoemde
potensiaal ten volle ontgin
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A Stylistic Analysis of Liszt's Settings of the Three Petrarchan Sonnets
Full text linkThis is a stylistic study of the four versions of Liszt's Three Petrarchan Sonnets with special emphasis on the revision of poetic settings to the music. The various revisions over four versions from 1838 to 1861 reflect Liszt's artistic development as seen especially in his use of melody, harmony, tonality, color, tone painting, atmosphere, and form. His use of the voice and development of piano technique also play an important part in these sonnets. The sonnets were inexplicably linked with the fateful events in his life and were in a way an image of this most flamboyant and controversial personality. This study suggests Liszt's importance as an innovator, and his influence on later trends should not be underestimated
Development of a patient-specific unicompartmental knee replacement
Full text linkThesis (PhD)--Stellenbosch University, 2018.ENGLISH ABSTRACT: Patient-specific Unicompartmental Knee Replacements (UKRs) could potentially restore an Osteoarthritic (OA) knee closer to its pre-pathological state than off-the-shelf products. Nevertheless, the current state-of-the-art is still
heavily reliant on a technician's interpretation and skill in order to reproduce healthy geometries. This dissertation therefore focused on developing a reliable,
semi-automated approach to implant design. Inter-patient variability and inter- and intra-observer agreement and reliability was studied for a set
of landmarks defined on the distal femur and proximal tibia. This provided necessary input to downstream processes. The variation in a populations'
knees was captured by Statistical Shape Models (SSMs), and the subsequent use of a Graphical User Interface (GUI) was investigated to incorporate local constraints as part of sparse SSM estimation. These estimates formed
the base of the implants' femoral components, and together with matching metal-backed, motion-guided tibial components were created using automated
B-spline parametrisations. Sixteen unseen knees were used as test candidates and it was found that the resulting condyle estimations were sufficiently accurate,
while the generated implant components matched normal knee anatomy.
Both the GUI-based estimation and the automated design process showed good repeatability. The implant design presented here is ready for pre-clinical testing and evaluation.AFRIKAANSE OPSOMMING: Pasiëntspesifieke Unikomaptementele Knie Vervangings (UKVs) kan moontlik 'n Osteoartritiese (OA) knie nader aan sy voorpatologiese toestand herstel as van-die-rak produkte. Nietemin, die huidige stand-van-die-kuns is steeds sterk afhanklik van die tegnikus se interpretasie en vaardigheid om gesonde geometrieë na te maak. Hierdie proefskrif het dus gefokus op die ontwikkeling
van 'n betroubare, semi-automoatiese benadering tot implantaat ontwerp.
Inter-pasiënt veranderlikheid en inter- en intra-waarnemer ooreenkoms en betroubaarheid
is bestudeer vir 'n stel landmerke wat op die distale femur en proximale tibia gedefinieer is. Dit het die nodige insette vir afstroomprosesse verskaf. Die variasie in 'n populasie se knieë is gevang deur Statistiese
Vormmodelle (SVs), en die daaropvolgende gebruik van 'n Grafiese Gebruikerskoppelvlak (GGK) is ondersoek om lokale beperkinge in te sluit as deel van 'n yl SV-skatting. Hierdie skattings het die basis van die implantate se
femorale komponente gevorm, en is geskep met behulp van geoutomatiseerde B-spline parametrisasies tesaam met die ooreenstemmende metaalgesteunde,
bewegingsgeleide tibiale komponente. Sestien versteekte knieë is as toetskandidate gebruik en daar is bevind dat die resulterende kondiele-skattings akkuraat
genoeg was terwyl die gegenereerde implantaat-komponente ooreenstem met normale knie anatomie. Beide die GGK-gebaseerde skattings en die outomatiese
ontwerpproses het goeie herhaalbaarheid getoon. Die implantaat ontwerp wat ons hier aanbied is gereed vir voor-kliniese toetsing en evaluering.Doctora
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