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Biomedical subjects

J B Williamson

Publications and source records attributed to J B Williamson.

At least 19 recordsLinked to original sources
PubMed2006

Homologous blood transfusion is not required in surgery for adolescent idiopathic scoliosis.

We studied 70 consecutive patients with adolescent idiopathic scoliosis who underwent corrective surgery. They were divided into two groups. In the study group of 38 patients one or more modern blood-conservation measures was used peri-operatively. The 32 patients in the control group did not have these measures. Both groups were similar in regard to age, body-weight, the number of levels fused and the type of surgery. Only two patients in the study group were transfused with homologous blood and these transfusions were 'off-protocol'. Wastage of autologous pre-donated units was minimal (6 of 83 units). By contrast, all patients in the control group were transfused with homologous blood. In the study group there was a significant decrease (p = 0.005) in the estimated blood loss when all the blood-conservation methods were used. The use of blood-conservation measures, the lowering of the haemoglobin trigger for transfusion and the education of the entire team involved in the care of the patient can prevent the need for homologous blood transfusion in patients undergoing surgery for adolescent idiopathic scoliosis.

Adolescent↗
PubMed2001

Late operative site pain with isola posterior instrumentation requiring implant removal: infection or metal reaction?

OBJECTIVES: To elucidate the cause of late operative site pain in six cases of scoliosis managed with Isola posterior instrumentation that required removal of the implants. METHOD: Microbiologic examination of wound swabs and enriched culture of operative tissue specimens was undertaken in all cases. Histologic study of the peri-implant membranes also was conducted. RESULTS: The presentation in all cases was similar: back pain appearing between 12-20 months after surgery, followed by a local wound swelling leading to a wound sinus. In only one of these cases was the discharge positive for bacterial growth. Implant removal was curative. Histologic examination of tissue specimens revealed a neutrophil-rich granulation tissue reaction suggestive of an infective etiology despite the failure to isolate organisms. Within the granulation tissue was metallic debris that varied from very sparse to abundant from fretting at the distal cross-connector junctions. A review of recent literature describing similar problems suggests that late onset spinal pain is a real entity and a major cause of implant removal. CONCLUSIONS: On reviewing the evidence for an infective etiology versus a metallurgic reaction etiology for these cases of late onset spinal pain, it was concluded that a subacute low-grade implant infection was the main cause. Histologic findings would seem to confirm low-grade infection. There may be more than one causative factor for late operative site pain, as it is possible that fretting at cross connection junctions may provide the environment for the incubation of dormant or inactive microbes.

Adolescent↗
PubMed2000

Social Security reform: implications for women.

Despite recent economic gains for women, a substantial gender gap in financial security during old age remains, making women more dependent than men upon Social Security. Social Security plays an important role in providing for women's economic security. The implications for women of several proposed changes in Social Security policy, including the call for the partial privatization of Social Security via the introduction of individual accounts, are analyzed. Many of the proposals would have the effect of asking women, particularly low-income women, to shoulder a disproportionate share of the risks and burdens associated with the changes.

Aged↗
PubMed1999

The clinical significance of the high-intensity zone on lumbar spine magnetic resonance imaging.

STUDY DESIGN: Prospective observational study of anular tears, diagnosed by a high-intensity zone within the anulus on lumbar spine magnetic resonance imaging, and correlation with the clinical features. OBJECTIVES: To assess the prevalence of high-intensity zones in patients who are investigated for back and leg pain and to determine whether there are clinical features that can be used for diagnosis of the presence of a high-intensity zone. SUMMARY OF BACKGROUND DATA: Results in previous studies have shown that the presence of a high-intensity zone is associated with reproduction of a patient's pain on stress discography. Neural compression on magnetic resonance imaging has been shown to be associated with back pain, but to date, no study has correlated the presence of a high-intensity zone with the clinical features. METHODS: The lumbar spine magnetic resonance images in 156 patients in whom back and leg pain were investigated were analyzed for the presence and appearances of high-intensity zones. The clinical features of those patients with a high-intensity zone but with no evidence of neural compression on magnetic resonance imaging were analyzed by t test and X2 test. RESULTS: A high-intensity zone occurred in patients at a prevalence of 45.5% and usually occurred posteriorly (77%) and posterolaterally (22%) within the anulus. There were no features within the history, functional disability questionnaire, or physical examination that aided in a clinical diagnosis of those patients with a high-intensity zone. CONCLUSIONS: A high-intensity zone is a common finding in patients in whom low back and leg pain are investigated, but the presence of a high-intensity zone does not define a group of patients with particular clinical features.

Adolescent↗
PubMed1999

Maternal mortality, women's status, and economic dependency in less developed countries: a cross-national analysis.

While much has been written about the medical, economic, and social causes of cross-national differences in some mortality related phenomena such as in life expectancy and infant mortality, much less attention has been given to maternal mortality, the focus of the present study. In the studies of maternal mortality that have been done, there has been very little effort to assess the potential relevance of the gender stratification and dependency theory perspectives. Using lagged cross-sectional and path analysis with a sample of 79 less developed countries, this article focuses on the impact of predictors linked to three theoretical perspectives - modernization, economic dependency, and gender stratification. We find that women's status, as measured by indicators such as level of education relative to men, age at first marriage, and reproductive autonomy, is a strong predictor of maternal mortality. We find that economic dependency, especially multinational corporate investment, has a detrimental effect on maternal mortality that is mediated by its harmful impacts on economic growth and the status of women. We also find support for developmental theory, a variant of modernization theory.

Adolescent↗
PubMed1998

The therapeutic impact of lumbar spine MRI on patients with low back and leg pain.

UNLABELLED: The influence of lumbar spine magnetic resonance imaging (MRI) on the management of patients with low back and leg pain, with a clinical diagnosis of neural compression, has been investigated by a controlled prospective observational study. The clinical features of the patients at the time of request for MRI have been compared with the subsequent management in order to define the clinical indications for lumbar spine MRI. METHODS: Clinical history, physical examination findings and tests of functional and psychological disability were all recorded at the time of request for MRI. Following MRI, patients were assessed without knowledge of the MRI findings and a diagnosis and management plan recorded. Immediate access to the MRI report and hard copy films was then provided and a revised diagnosis and management plan made. The clinical features and MRI findings were compared with the subsequent management. RESULTS: Seventy-two patients were examined, 65 (90.3%) had leg pain as a predominant feature and abnormalities in neurological examination were found in 31 (43%). Twenty-three of 48 (47.9%) of patients with a pre MRI management plan of surgery were changed to conservative management following the MRI. The diagnosis altered in 50 % of cases with the largest change in diagnosis occurring in 13 patients where MRI did not confirm the clinical impression of nerve root compression. Seventeen patients with no abnormality of neurological testing were subsequently treated by surgery which included all 12 patients treated by spinal fusion. CONCLUSIONS: The major impact of MRI was to move patients towards conservative treatment. A variety of features in the history and physical examination as well as MRI findings are predictors for surgical treatment. The variety of diagnoses and surgical options available make it difficult to define clear clinical guidelines for the use of MRI.

Adult↗
PubMed1997

Measurement of vertebral rotation in adolescent idiopathic scoliosis using three-dimensional magnetic resonance imaging.

STUDY DESIGN: This report examines a technique for measurement of axial vertebral rotation using magnetic resonance imaging. OBJECTIVES: To assess the reproducibility of three-dimensional magnetic resonance imaging in the measurement of vertebral rotation at individual endplates in patients with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Deformity in the sagittal and coronal planes in patients with adolescent idiopathic scoliosis can be readily assessed from plain radiographs, but the degree of deformity in the axial plane is more difficult to determine. Plain film techniques have inherent inaccuracies because of loss of definition of anatomic landmarks, and the use of computed tomography is limited by the high radiation dose associated. Magnetic resonance imaging provides a means of imaging scoliotic deformity that allows multiplanar reconstruction and that involves no use of ionizing radiation. METHODS: Ten patients with adolescent idiopathic scoliosis were imaged in a Siemens 1-Tesla impact scanner. Three-dimensional volume images of the apical five vertebrae were obtained in the axial plane and were postprocessed through multiplanar reconstruction. Sections through the superior and inferior endplates of each vertebra were selected in the sagittal and coronal planes, allowing axial reconstructions to be obtained in the plane of each endplate. Vertebral rotation was measured by identifying datum points on the inner surfaces and at the junction of the laminas and comparing the angle subtended by these points with a vertical drawn by the computer. Measurements were obtained from the single scanning sequence on two occasions by one observer and on one occasion by a second observer. Interobserver and intraobserver error was evaluated and correlation with readings obtained from plain films using Perdriolle's torsiometer method assessed. RESULTS: The interobserver variation had a mean of 3.02 degrees (range, 0-10 degrees) and a 95% confidence interval of [2.51 degrees, 3.53 degrees]. The intraobserver variation had a mean of 2.56 degrees (range, 0-7 degrees) and a 95% confidence interval of [1.83 degrees, 3.29 degrees]. The mean difference between measurements obtained from magnetic resonance imaging and plain film was 3.29 degrees (range, 0-12 degrees) with a 95% confidence interval of [1.43 degrees, 5.15 degrees]. CONCLUSIONS: The degree of vertebral rotation can be accurately and reproducibly assessed by three-dimensional magnetic resonance imaging. Measurements can be made through individual endplates that allow assessment of the relative amount of intervertebral and intravertebral deformity.

Adolescent↗
PubMed1997

MRI appearance of popliteal cysts in childhood.

Popliteal cysts are soft fluid-filled lesions of synovial origin which result from extrusion of joint fluid into the gastrocnemiosemimembranous bursa. They may occur in any age group, but 22-33 % occur in the first 15 years of life. In this age group they are rarely associated with intraarticular abnormalities and therefore rarely require treatment. This case report shows the magnetic resonance imaging (MRI) appearances of a popliteal cyst in two children.

Child↗
PubMed1997

Female life expectancy, gender stratification, health status, and level of economic development: a cross-national study of less developed countries.

A number of studies have attempted to account for cross-national differences in life expectancy, but relatively few have focused on female life expectancy, and even fewer on the relevance of predictors linked to gender stratification theory. The present study seeks to assess the utility of gender stratification theory in accounting for cross-national differences in female life expectancy in less developed countries. An incremental model building strategy is used to develop a final model that combines predictors linked to both industrialism theory and gender stratification theory. The analysis is based on multiple regression and cross-sectional samples that vary in size from 40 to 97 countries. Evidence is presented that several aspects of women's status have a positive effect on female life expectancy. Indicators of women's educational status, women's economic status, and women's reproductive autonomy all prove to be important predictors of female life expectancy. Analysis of interaction effects suggests that the strength of the effects of some aspects of women's economic status and the effect of some aspects of health status on female life expectancy vary with the level of economic development. A comprehensive assessment of the relative strength of alternative measures of women's education is carried out, and evidence is presented that it does make a difference how the level of women's education is measured.

Adolescent↗
PubMed1997

A critique of the case for privatizing Social Security.

This article presents and then critiques arguments made by those advocating the privatization of Social Security. It refutes the argument that baby boomers will find themselves without Social Security pensions unless fundamental changes are made. It questions the claims that privatization would increase economic growth, reduce the federal deficit, make the nation more competitive in the global economy, protect workers against payroll tax increases, protect boomers against pension benefit cuts, and increase confidence in Social Security. It argues that for low-wage workers, returns on contributions would probably decrease and future benefits would become politically more vulnerable.

Aged↗
PubMed1996

Spinal problems in mucopolysaccharidosis I (Hurler syndrome).

Bone-marrow transplantation has increased the survival of patients with mucopolysaccharidosis-I. We describe the spinal problems and their management in 12 patients with this disorder who have been followed up for a mean of 4.5 years since transplantation. High lumbar kyphosis was seen in ten patients which was associated with thoracic scoliosis in one. Isolated thoracic scoliosis was seen in another. One patient did not have any significant problems in the thoracic or lumbar spine but had odontoid hypoplasia, which was also seen in three other children. Four of the eight patients in whom MRI of the cervical spine had been performed had abnormal soft tissue around the tip of the odontoid. Neurological problems were seen in two patients. In one it was caused by cord compression in the lower dorsal spine 9.5 years after posterior spinal fusion for progressive kyphosis, and in the other by angular kyphosis with thecal indentation in the high thoracic spine associated with symptoms of spinal claudication.

Adolescent↗
PubMed1996

Preserving confidentiality and security of patient health care information.

The lack of a uniform legal or regulatory scheme that applies to the protection of privacy in health care information and marketplace pressures placed on health care providers for access to patient data require physicians, hospitals, and other health care providers to establish and maintain security measures to protect against unauthorized access to patient records and vigilantly safeguard against improper disclosure.

Computer Security↗
PubMed1995

Lung function in Duchenne muscular dystrophy.

Over 90% of patients with Duchenne muscular dystrophy develop a scoliosis when they become wheelchair bound. The scoliosis is progressive and is associated with deteriorating lung function. The purpose of this study was firstly to assess whether a standing regimen, in patients who had gone off their feet, protected against the development of scoliosis and affected their lung function, and secondly to evaluate the effect of spinal stabilisation in patients who had developed a progressive scoliosis. The results of the first part of this study showed that a standing regimen significantly delayed the progression of scoliosis and that patients who complied with the standing regimen had a significantly better lung function, as measured by vital capacity and peak expiratory flow rate, than those patients who did not stand. Spinal stabilisation prevented deterioration in the scoliosis, whereas the deformity continued to progress relentlessly in patients who did not undergo surgery. The patients who underwent spinal stabilisation maintained a significantly better lung function and had an improved survival compared with the patients who refused surgery.

Child↗
PubMed1995

Scoliosis and lung function in spinal muscular atrophy.

The notes and radiographs of 43 patients with a confirmed diagnosis of spinal muscular atrophy were reviewed. A significant inverse linear relationship between the severity of scoliosis and the percentage of predicted vital capacity and peak flow was found. The patients who stood had a significantly better lung function than patients who were confined to a wheelchair, and their scoliosis deteriorated significantly more slowly. Sixteen patients underwent surgical spinal stabilisation, 4 with Harrington instrumentation and 12 with segmental spinal instrumentation, at an average age of 12 years and 11 months. The average curve correction achieved was 40%. The decline in lung function seen pre-operatively was not only reversed, but a significant improvement was found at final follow-up.

Adolescent↗