Friction in metal-on-metal total disc arthroplasty: effect of ball radius

Total Disc Arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening. This study was designed to determine the effects of ball radius on friction. Generic models of metal-on-metal TDA were manufactured with ball radii of 10, 12, 14 and 16 mm, with a radial clearance of 0.015 mm. A simulator was used to test each sample in flexion-extension, lateral bending and axial rotation at frequencies of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 Hz under loads of 50, 600, 1200 and 2000 N, in new born calf serum. Frictional torque was measured and Stribeck curves were plotted to illustrate the lubrication regime in each case. It was observed that implants with a smaller ball radius showed lower friction and showed boundary and mixed lubrication regimes, whereas implants with larger ball radius showed boundary lubrication only. This study suggests designing metal-on-metal TDAs with ball radius of 10 or 12 mm, in order to reduce wear and implant loosening

A review of measles notification for Soweto for the period 1984 to 1986

Thesis submitted to the Faculty Of Health Sciences, University of the Witwatersrand, Johannesburg for the partial fulfilment for the degree of Master in Medicine in Community HealthPrior to 1986, Sowetan children were vaccinated against measles on two occasions at 6 and 12 months of age. In order to comply with the World Health Organisation's recommendation for African countries, this schedule was changed in January 1986 to one vaccination at 9 months of age. At the time of this change in the measles vaccination schedule, there was a reported increase m the incidence of measles at hospitals that serve the population of Soweto. This was thought to represent a general increase in the incidence of measles in Soweto. This study set out to investigate this reported increase in the incidence of measles over the period. A retrospective record review of notification forms was undertaken.IT201

Day clinics and hospitals - a cost comparison

Objective. To determine the types of surgical procedures currently undertaken in day clinics and to compare the number of procedures, the average in-facility cost, and the pre- and post-discharge costs for each procedure or group of procedures.Design. A retrospective descriptive study of medical aid claims data.Setting. Department of Family Medicine, University of the Witwatersrand, Johannesburg.Subject. Three private sector medical aid schemes with in excess of 170 000 principal members (380 000 lives).Outcome measures. For each surgical procedure. the following were compared: (i) the total number of procedures done; (ii) the average total in-facility cost; and (iii) the cost of professional fees and medicines for 7 days before admission, during admission, and for 14 days after discharge.Results. During 1997, 89 216 patients underwent surgery. Day clinics and hospitals accounted for 5 490 and 83 726 admissions respectively. Fifty-one different types of procedures were identified that met the inclusion criteria.On average the in-facility costs for 45 (88%) of the 51 compared procedures were lower in day clinics compared with hospitals. Average costs can be as much as 90% lower in day clinics. Some procedures, particularly certain dental operations, cost more in day clinics. The professional fees of attending doctors and the cost of medicines are generally higher when the procedure is undertaken in a hospital.Conclusion. In South Africa, as is the case in the USA, day clinics have the potential to reduce the cost of surgical procedures

Enhancing surveillance for exotic stored pests in the Australian grains industry using a partnership approach with industry and government

Verifying freedom from exotic pests such as Khapra beetle (Trogoderma granarium) & Karnal Bunt (Tilletia indica) is critical to supporting & maintaining access for Australian grain producers to international markets. Despite Australia's geographical isolation & strong quarantine systems, increasing levels of travel & trade continues to place pressure on our biosecurity systems, emphasising the need for improving our regional efforts in prevention, preparedness & surveillance to mitigate risks. The Australian Grains Farm Biosecurity Program (GFBP) is a national initiative to assist in the development & implementation of improved biosecurity practice, playing a vital role in the education of exotic pests & the role of surveillance by industry. The GFBP has undertaken a targeted surveillance program for stored product pests, with Khapra beetle as the main focus. A range of sites based on potential risk groups & pathways (e.g. farming enterprises, seed distributors & agricultural stores) were targeted, with different approaches used across the three grain growing regions of Australia depending on State activities & pre-existing collaborators. All regions used a combination of pheromone traps & other sampling methods appropriate for host materials & environment. The surveillance is aimed at strengthening evidence of absence, building industry knowledge & participation in grain storage surveillance & promoting improved management practices around storage. These regionally specific engagement methods & surveillance efforts are discussed. Australia remains free of Khapra beetle

Enhancing surveillance for exotic stored pests in the Australian grains industry using a partnership approach with industry and government.: Presentation

Verifying freedom from exotic pests such as Khapra beetle (Trogoderma granarium) & Karnal Bunt (Tilletia indica) is critical to supporting & maintaining access for Australian grain producers to international markets. Despite Australia’s geographical isolation & strong quarantine systems, increasing levels of travel & trade continues to place pressure on our biosecurity systems, emphasising the need for improving our regional efforts in prevention, preparedness & surveillance to mitigate risks. The Australian Grains Farm Biosecurity Program (GFBP) is a national initiative to assist in the development & implementation of improved biosecurity practice, playing a vital role in the education of exotic pests & the role of surveillance by industry. The GFBP has undertaken a targeted surveillance program for stored product pests, with Khapra beetle as the main focus. A range of sites based on potential risk groups & pathways (e.g. farming enterprises, seed distributors & agricultural stores) were targeted, with different approaches used across the three grain growing regions of Australia depending on State activities & pre-existing collaborators. All regions used a combination of pheromone traps & other sampling methods appropriate for host materials & environment. The surveillance is aimed at strengthening evidence of absence, building industry knowledge & participation in grain storage surveillance & promoting improved management practices around storage. These regionally specific engagement methods & surveillance efforts are discussed. Australia remains free of Khapra beetle.Verifying freedom from exotic pests such as Khapra beetle (Trogoderma granarium) & Karnal Bunt (Tilletia indica) is critical to supporting & maintaining access for Australian grain producers to international markets. Despite Australia’s geographical isolation & strong quarantine systems, increasing levels of travel & trade continues to place pressure on our biosecurity systems, emphasising the need for improving our regional efforts in prevention, preparedness & surveillance to mitigate risks. The Australian Grains Farm Biosecurity Program (GFBP) is a national initiative to assist in the development & implementation of improved biosecurity practice, playing a vital role in the education of exotic pests & the role of surveillance by industry. The GFBP has undertaken a targeted surveillance program for stored product pests, with Khapra beetle as the main focus. A range of sites based on potential risk groups & pathways (e.g. farming enterprises, seed distributors & agricultural stores) were targeted, with different approaches used across the three grain growing regions of Australia depending on State activities & pre-existing collaborators. All regions used a combination of pheromone traps & other sampling methods appropriate for host materials & environment. The surveillance is aimed at strengthening evidence of absence, building industry knowledge & participation in grain storage surveillance & promoting improved management practices around storage. These regionally specific engagement methods & surveillance efforts are discussed. Australia remains free of Khapra beetle

Removal of nucleus pulposus from the intervertebral disc – the use of chymopapain enhances mechanical removal with rongeurs: a laboratory study

<p>Abstract</p> <p>Background</p> <p>A laboratory study was conducted, on cadaveric sheep spines to develop an effective procedure for removing as much nucleus as possible from an intervertebral disc with minimal disruption to the annulus. The results of many studies involving removal of nucleus, including chemonucleolysis, using chymopapain, have been published but we are not aware of any previous quantitative studies on procedures for removing as much nucleus as possible from the disc.</p> <p>Methods</p> <p>All procedures were performed via a 3 mm trocar. Four procedures were compared: (I) unilateral approach using rongeurs alone, (II) bilateral approach using rongeurs alone, (III) unilateral approach using rongeurs followed by chymopapain and (IV) bilateral approach using rongeurs followed by chymopapain.</p> <p>Results</p> <p>The percentages of nucleus removed were: (I) 34%, (II) 41%, (III) 52% and (IV) 75%; there were significant differences between the four sets of results according to ANOVA.</p> <p>Conclusion</p> <p>Significantly more nucleus is removed using a bilateral than a unilateral approach; significantly more nucleus is removed if chymopapain is used in addition to rongeurs. A brush is useful in removing strands of nucleus loosened by chymopapain.</p

Feasability of Preventing Encrustation of Urinary Catheters

Colonization of urinary catheters by bacteria which produce urease leads to an increase in urine pH, followed by deposition of the minerals struvite and hydroxyapatite. Adhesion of these encrusting deposits can be reduced, but not prevented, by using catheters with a smooth surface finish. Chemical methods for preventing encrustation are not completely satisfactory. A better way of preventing encrustation would be to prevent colonization of the catheter by bacteria. This might be achieved by controlled release of antimicrobial agents directly into the urine from the catheter itself. Preliminary experiments have demonstrated the feasibility of controlled release from solid silicone. However, a simpler approach is diffusion of an antimicrobial agent from a solution within the retention balloon of the catheter. Further experiments are required to determine the concentrations required and whether they are achievable in practice