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Biomedical subjects

V Tan

Publications and source records attributed to V Tan.

At least 19 recordsLinked to original sources
PubMed2005

Prescribing pattern in Parkinson's disease: are cost and efficacy overriding factors?

Information on prescribing pattern of antiparkinsonian medications and factors influencing neurologists' choice of such drugs are important considerations in evaluating healthcare cost of Parkinson's disease (PD). We surveyed neurologists' perceived factors influencing their choice of drugs and actual prescribing pattern in PD. Three hundred and six patients at a tertiary hospital, diagnosed with idiopathic PD and who were dispensed antiparkinsonian drugs during a 6-month period were randomly selected. Patient demographics, type and dose of medications were analysed. A questionnaire survey evaluating the factors influencing choice of medications was administered to neurologists who practiced at the institution. The study population had a mean age of 64.4 years (SD +/- 9.9 years), and more than 80% were at Hoehn & Yahr stage 2-3. 92.3% of the study population were receiving levodopa and monotherapy, with levodopa being the most common treatment regimen. Patients who were prescribed levodopa were significantly older and at a later stage of disease compared to those without levodopa (p < 0.05). Only 26.8% of patients were prescribed dopamine agonists. In the survey, the neurologists cited severity of symptoms, and patients' intolerance of side effects, and efficacy as the most important factors influencing their choice of drugs. However, the actual prescribing pattern revealed a strong positive correlation of drug usage with cost subsidy by the institution. While factors affecting drug usage in PD are well recognised, cost and efficacy of a drug appear to be overriding practical factors in influencing usage pattern in clinical practice.

Aged↗
PubMed2002

Independent contribution of elevated-rim acetabular liner and femoral head size to the stability of total hip implants.

The use of an elevated-rim acetabular liner in total hip arthroplasty is widely accepted. We sought to determine quantitatively the amount of additional stability provided by the elevated-rim liner compared with the standard nonelevated liner. The stability of the hip with a 32-mm femoral head was compared with the standard 28-mm head. Our results show that a 15 degrees elevated-rim acetabular liner placed in the posterior quadrant increased hip stability by an additional 8.9 degrees of internal rotation. Similarly the 32-mm head provided 8.1 degrees of additional internal rotation. The increases were statistically significant (P<.0001). We did not encounter increased anterior dislocation intraoperatively. The findings of this study indicate that the 32-mm head may contribute to hip stability in primary total hip arthroplasty, and in instances in which a posterior approach is used, an elevated-rim liner placed in the posterior quadrant may contribute independently to hip stability.

Acetabulum↗
PubMed2001

Anatomy, histologic features, and vascularity of the adult acetabular labrum.

Acetabular labrum tears have been implicated as a cause of hip pain in adult patients. Few studies describe the anatomy, histologic features, and microvasculature of the acetabular labrum and labral tears. Fifty-five embalmed and 12 fresh-frozen adult hips with a mean age of 78 years (range, 61-98 years) were studied. Of these, 96 % (53 of 55) of the hips had labral tears, with 74% of the tears located in the anterosuperior quadrant. Histologically, the fibrocartilaginous labrum was contiguous with the acetabular articular cartilage through a 1- to 2-mm zone of transition. A consistent projection of bone extends from the bony acetabulum into the substance of the labrum that is attached via a zone of calcified cartilage with a well-defined tidemark. Two distinct types of tears of the labrum were identified histologically. The first consisted of a detachment of the fibrocartilaginous labrum from the articular hyaline cartilage at the transition zone. The second consisted of one or more cleavage planes of variable depth within the substance of the labrum. Both types of labral tears were associated with increased microvessel formation seen within the tear. The acetabular labrum tear appears to be an acquired condition that is highly prevalent in aging adult hips. Labral tears occur early in the arthritic process of the hip and may be one of the causes of degenerative hip disease.

Acetabulum↗
PubMed2001

In-line skating injuries.

In-line skating has remained a popular recreational activity all over the world. The number of injuries seemingly reached a plateau in the late 1990s. However, there are still more injuries caused by in-line skating than from skateboarding, hockey or lacrosse and rugby. In 1997, the estimated annual cost of medical treatment for these injuries in the US was over $US4 billion. Adolescence still represents the largest group of skaters, both in participation and injury. Although 10- to 14-year-olds account for 60% of injuries, in 1996 the US Consumer Product Safety Commission reported nearly 1500 injuries in individuals 65 years and over. Risk factors for injury include inexperience, aggressive skating and amount of time spent skating. There are also more recent data to suggest that self-reported expert skaters are more likely to sustain an injury. Reluctance to use personal protective equipment (PPE) by in-line skaters remains high. The general consensus is that PPE is effective in reducing the incidence and severity of in-line skating injuries. Therefore, efforts should be made to increase awareness of risk factors for injury in all skaters; to increase use of safety equipment; to provide safe environments for skating; and to legislate skating laws that will protect skaters from injuries.

Accidental Falls↗
PubMed2001

Contribution of acetabular labrum to articulating surface area and femoral head coverage in adult hip joints: an anatomic study in cadavera.

The purpose of our study was to describe the gross anatomy of the adult acetabular labrum and to determine its contribution to the depth, surface area, and volume of the acetabulum. Fifty-five embalmed hips were studied. Each hip was disarticulated, and standardized measurements were taken. Calculations of the acetabular articulating surface area and volume, with and without the labrum, were performed based on these measurements. Average width of the acetabular labrum was 5.3 mm (SD, 2.6 mm). The labrum was wider anteriorly and superiorly than posteriorly. The surface area of the acetabulum without the labrum was 28.8 cm2; with the labrum, it was 36.8 cm2 (P < .0001). The volume of the acetabulum without the labrum was 31.5 cm3; with the labrum, it was 41.1 cm3 (P < .0001). There was no side-to-side difference in contribution of the labrum to either surface area or volume between right and left hips. Comparison of these indices for males and females showed statistically significant differences in absolute but not relative increases.

Acetabulum↗
PubMed2000

Ageing and fitness to work.

Ageing workers can be found in almost all occupations. Assessment of fitness to work in these workers is important, as it aims to match their functional capacity (which is reduced compared to younger workers), to the demands of their work (which may remain the same as that for younger workers). This outcome of assessment is influenced by the interaction between functional capacity, state of health, the nature of work, and possibilities for work accommodation. The assessment of functional capacity should include physical, mental and social capacity, as well as assessment of any disability. In addition to clinical or laboratory measurements, several authors have suggested the use of a 'work ability index' for specific occupations as a practical means of selecting the appropriate worker for the job. This index can also be used for monitoring functional capacity. In addition, as for any fitness to work assessment, a good understanding of the nature of the work and the work environment is required, and possibilities for work accommodations considered. While changes in the work environment and working conditions can be made to suit the functional capacity of the ageing worker, the maintenance of functional capacity is another important issue. There is a place for a greater role for disease screening and health promotion for such workers.

Aged↗
PubMed2000

Major pediatric hand trauma associated with fireworks.

OBJECTIVES: To characterize the injury pattern and economic impact of major pediatric hand trauma secondary to fireworks. DESIGN: Retrospective. SETTING: Pediatric Level I trauma center. INTERVENTION: N/A MAIN OUTCOME MEASUREMENTS: Fractures, amputations, soft tissue defects, length of hospitalization, number and type of procedures performed were obtained from charts, radiographs, and operative reports. Hospital charges were obtained from the billing office. PATIENTS/PARTICIPANTS: Records of patients with a diagnosis of fireworks-related injuries admitted over a period of ten years were reviewed. Twenty-two patients were identified to have sustained twenty-two hand injuries. The group consisted of nineteen boys and three girls, with an average age of 9.3 years (range, 4 to 17 years). RESULTS: There were thirty-one fractures, nineteen amputations, and one dislocation. The nineteen amputations occurred in nine hands. Local skin graft or flap coverage was required in six hands acutely, and delayed soft tissue procedures were performed on four hands. Four hands had digital neurovascular injuries; two required microsurgical repairs at the time of injury, and two were irreparable. Resource use included: average hospital stay of 4.3 days (range, 0 to 20), average number of trips to the operating room, 1.2 (range, 0 to 3), and average hospital charges of $11,582 (range, $1,035 to $39,489). CONCLUSIONS: This study illustrates the severity of pediatric hand injuries associated with fireworks and the significant burden placed on medical resources in treating these injuries. Efforts toward public education and legislative reforms may help to prevent these unnecessary injuries.

Adolescent↗
PubMed1999

A comparison of various angles of halo pin insertion in an immature skull model.

STUDY DESIGN: A basic science biomechanical study involving an animal model. OBJECTIVES: To evaluate the effect of varying angles of halo pin insertion on the force generated at the pin-bone interface, and thereby the stability of the halo pin-bone interaction during insertion. BACKGROUND DATA: Because of variations in the shape and size of the pediatric skull, halo pins often are inserted at various angles rather than perpendicular to the skull. Concern exists that the high complication rate associated with pediatric halo use may result in part from less than ideal structural properties at the halo pin-bone interface. METHODS: The authors used a fetal calf skull model to simulate the thickness and structural properties of the pediatric skull. Halo pins were inserted at angles of 0 degree (perpendicular), 10 degrees, 15 degrees, and 30 degrees into skull segments via a halo ring. Load generated at the pin-bone interface was measured using a modified mechanical testing device. Twenty trials were conducted per angle, with the endpoint being specimen failure, pin penetration, or maximum load. RESULTS: Mean maximum loads per unit thickness were 82.15 +/- 7.54 N/mm at 0 degree, 68.80 +/- 4.79 N/mm at 10 degrees, 51.49 +/- 5.08 N/mm at 15 degrees, and 42.38 +/- 3.51 N/mm at 30 degrees, There was a significant difference between perpendicular insertion (0 degree) and 15 degrees angles of insertion. There was also a significant difference between the 10 degrees and 30 degrees angles of insertion. CONCLUSIONS: Perpendicular halo pin insertion in an immature skull model was shown to result in increased load at the pin-bone interface. This improved structural behavior may help to reduce the incidence of complications of halo application in children.

Animals↗
PubMed1999

Total knee arthroplasty for steroid-induced osteonecrosis.

There have been only a few reports that evaluate the outcome of total knee arthroplasty in patients with steroid-induced osteonecrosis of the knee. We retrospectively reviewed 31 total knee arthroplasties in 24 patients with confirmed steroid-induced osteonecrosis of the knee. The average follow-up was 64 months. Of surviving knees, 92% had significant improvement in knee scores. Five knees (16%) required a revision procedure. Reasons for revision were aseptic loosening in 3 knees and sepsis in 2 knees. Complications not requiring revision occurred in 6 of 31 knees (19%). Survivorship of total knee arthroplasty to revision in patients with steroid-induced avascular necrosis of the knee was 84% at 5 years. Although there was a slightly higher complication rate, this may, in part, be due to the severity of the patients' underlying disease processes. Total knee arthroplasty can be a successful procedure for chronically ill patients with steroid-induced osteonecrosis.

Adult↗
PubMed1999

Predictors of injury among adult recreational in-line skaters: a multicity study.

OBJECTIVES: This study examined risk factors for injury, injury prevalence, safety gear use, and skating habits of adult recreational in-line skaters. METHODS: Randomly selected in-line skaters in 6 major US cities were interviewed. RESULTS: Only 6% of skaters consistently wore all 4 recommended types of safety gear. Skaters with greater skating experience were more likely to perform tricks, wear less safety gear, and sustain an injury. CONCLUSION: More experienced adult recreational in-line skaters are at increased risk for injury. Safety gear use in alarmingly low in adult recreational in-line skaters, especially experienced skaters. Safe skating education programs should consider targeting this newly recognized at-risk skating population.

Adult↗
PubMed1998

The effect of shear stress on fibroblasts derived from Dupuytren's tissue and normal palmar fascia.

This study examines the real-time intracellular calcium changes of palmar fascia from normal and Dupuytren's diseased fibroblasts in response to shear stress. The real-time cytosolic calcium changes were measured using fluorescence microscopy image processing. The preconfluent primary cultured cells were exposed to 1 minute of flow at 25 dyne/cm2 after a 2-minute baseline of no flow. Additionally, the cells were exposed to an influx of Hank's buffered saline solution with 2% newborn bovine serum to examine the response to serum-born (chemical) agonists. Cytosolic calcium changes were measured as the percentage change over the 2-minute baseline of the mean [Ca2+]i peak. The mean change of the peak [Ca2+]i response of the normal palmar fascia was significantly greater than that of the cells from the Dupuytren's nodular and perinodular tissue. The response to the chemical agonist showed a robust but not statistically different response between the 3 cell types. Our work supports the hypothesis that palmar fascia responds to mechanical stress, specifically laminar fluid flow. These findings may help to explain that an underlying abnormality in the cells of the palmar fascia may be expressed by exposure to laminar fluid flow, a physical signal, rather than a chemical agonist.

Adult↗
PubMed1998

Phase I study of paclitaxel (taxol) and granulocyte colony stimulating factor (G-CSF) in patients with unresectable malignancy.

A phase I trial of a 24-hour infusion of paclitaxel was conducted to identify the maximum tolerated dose of paclitaxel with granulocyte colony-stimulating factor (G-CSF) in patients with unresectable malignancy previously untreated with chemotherapy. Nineteen patients with metastatic melanoma or non-small cell lung cancer were treated with paclitaxel administered at 250, 300, 400 mg/m2 every 3 weeks. G-CSF, 5 microg/kg was given as a daily subcutaneous injection 24 hours after the completion of the infusion. Dose limiting myelosuppression and peripheral neuropathy was observed at 400 mg/m2 and 350 mg/m2. Paclitaxel can be safely administered as a 24-hour infusion at 300 mg/m2 with G-CSF. Further studies of paclitaxel and G-CSF are recommended to determine a dose-response relationship in sensitive tumors.

Adult↗
PubMed1998

A comparative evaluation of halo pin designs in an immature skull model.

To design an improved halo pin for use in pediatric patients, three commonly used halo pins were evaluated with a mechanical testing apparatus and segments of prepared fetal calf skull. The pins were driven through the bone segments while the load at the bone-pin interface was measured. New pins were designed with respect to pin tip and flange width and similarly compared. Mean maximum loads to penetration, normalized for bone segment thickness, were 55.6 N/mm for the PMT Corporation pin, 61.5 N/mm for the Bremer pin, and 73.6 N/mm for the Ace pin. Four new, short tipped pins were designed and compared with the Ace pin, and there was no significant difference. Finally, four new pins were designed with varying flange widths. Mean maximum loads, normalized for bone segment thickness, were 68.9 N/mm for the 4.2 mm flange, 72.2 N/mm for the 4.7 mm flange, 92.9 N/mm for the 5.2 mm flange, and 96.4 N/mm for the 5.7 mm flange. The findings of this investigation are clinically important because they may help to explain the variability in the complication rates seen with the use of different halo systems in children. The three halo pins currently on the market have different pin designs, including tip lengths and flange distances, which contribute to the difference in load to penetration for each pin. The new, wide flanged, short tipped halo pin design might decrease the complication rate of halo use in children by providing an improved capacity to resist penetration despite increased loads of application.

Animals↗