Analysis of stress distribution in lumbar interbody fusion.

STUDY DESIGN: A 2-dimensional axisymmetric finite element model of an intervertebral segment was used to investigate the stress patterns in the adjacent vertebrae of fused spinal segment incorporating 4 common cage designs. The same was used to study the effect of maturation of bone graft on stress distribution pattern. OBJECTIVES: To study and compare the stress distribution patterns in a normal spinal segment and in the adjacent vertebrae of a fused spinal segment. The effect of bone graft incorporation around the mesh cage was also investigated. SUMMARY OF BACKGROUND DATA: Lumbar fusion surgery is thought to relieve discogenic low back pain by eliminating the abnormal intersegmental movement at the level of disc degeneration. Successful spinal fusion does not guarantee symptomatic pain relief. Discogenic pain is also known to be associated with an abnormal load transmission pattern across the degenerate disc. We hypothesized that the lumbar interbody fusion results in relief of discogenic pain by normalizing the load distribution pattern. METHODS: We used a 2-dimensional axisymmetric finite element model of an intervertebral segment to investigate the stress patterns in the vertebrae adjacent to a fused spinal segment incorporating 4 common cage designs: (1) anterior lumbar interbody fusion, (2) posterior lumbar interbody fusion rectangular, (3) posterior lumbar interbody fusion threaded, and (4) mesh cage. RESULTS: High stress concentrations and abnormal overall stress patterns were noted for all the cage designs studied. The anterior lumbar interbody fusion cage with its larger contact area showed the least abnormal stress magnitude in comparison with the other cages. Incorporation of bone in and around the mesh cage increased the area of contact and decreased the abnormal high stresses. The spine fusion model representing final bony healing showed restoration of near physiologic stress pattern. CONCLUSIONS: Interbody fusion cages with larger area of contact between cage and vertebral endplate produces a lower stress distribution pattern. A successful bony fusion restores near physiologic stress distribution pattern. Restoration of near normal load distribution pattern may become an important aim of surgery for discogenic low back pain.

An exploratory study of language interpretation services provided by videoconferencing.

We explored the feasibility and acceptability of the remote provision of a language interpretation service during general practice consultations. Three methods were used to provide an interpretation service: a physically present interpreter (PI), a remote interpreter accessed using an ISDN videoconferencing link at 128 kbit/s (VI) and a remote interpreter accessed by telephone (TI). Thirty-six non-English-speaking patients were invited to take part and 35 agreed to do so. Twenty-nine (83%) of the patients recruited were female. The age range of the participants was 24-51 years. Fourteen consultations took place with a physically present interpreter, 11 using videoconferencing and 10 using the telephone. Mean scores on the Patient Enablement Instrument were 5.2 for the PI group, 2.3 for the VI group and 5.1 for the TI group. Mean scores on the Medical Interview Satisfaction Scale were 5.3 for the PI group, 4.9 for the VI group and 5.3 for the TI group. The visual quality and sound quality of remote interpreting were satisfactory. Both videoconferencing and hands-free telephones can deliver an acceptable interpreting service in primary care.

Living with and dying from cancer: a humanities special study module.

We describe a humanities-based, special studies module (SSM) exploring the impact of cancer on the lives of patients, families and professionals. Literature, film, art and drama provide third year medical undergraduates with vicarious experience of all of these perspectives in a format that has proved highly acceptable to students and tutors. The development, delivery, evaluation and evolution of this humanities-based course are described and we highlight some important elements of course organisation that emerged as being integral to its success.

Street talk: knowledge and attitudes about tuberculosis and tuberculosis control among homeless adults.

OBJECTIVES: To measure knowledge and perceived susceptibility to tuberculosis among homeless adults in San Francisco and attitudes toward control measures used to improve adherence to treatment for tuberculosis. DESIGN: A cross-sectional survey via interview of homeless shelter residents was done at five shelters. RESULTS: Of 292 persons interviewed, 21.6% reported a positive skin test, and 57.1% of the positives had received preventive therapy. Over 60% had misconceptions about transmission, in particular confusion with transmission of the human immunodeficiency virus (HIV). Knowledge of skin testing procedures and symptoms was generally good, and most reported health care providers as the main source of information. Over half reported concern about catching tuberculosis and over 80% favored controls to ensure adherence, in particular directly observed therapy. Higher TB knowledge score (P = 0.0155) and male sex (P = 0.0357) were associated with a favorable attitude toward directly observed therapy. CONCLUSIONS: Health care providers should expand educational messages beyond skin testing. Greater knowledge about tuberculosis may increase acceptance of control measures. Targeted education plus social norms favoring completion of therapy may improve screening and treatment outcomes in this population.

Primary care units in A&E departments in North Thames in the 1990s: initial experience and future implications.

BACKGROUND: In 1992, the Tomlinson Report recommended a shift from secondary to primary care, including specific primary care provision in accident and emergency (A&E) departments. Availability of short-term so-called Tomlinson moneys allowed a number of experimental services. A study of the experience of A&E-based staff is reported to assist general practitioners (GPs) and purchasers and identify areas for further research. AIMS: To find the number and scope of primary care facilities in A&E services in North Thames; to find factors encouraging or inhibiting the setting-up of a successful service; to examine the views of a range of A&E staff including GPs, consultants, and nurses; and to suggest directions for more specific research. METHOD: A postal questionnaire was sent to all North Thames A&E departments, and an interview study of staff in one unit was arranged, leading to a questionnaire study of all GPs employed in North Thames primary care services in A&E. This was followed by interviews of staff members in five contrasting primary care units in A&E. RESULTS: By mid-1995, at least 16 of the 33 North Thames A&E departments ran a primary care service. Seven mainly employed GPs, the others employed nurse practitioners (NPs). Problems for GPs included unclear role definition and their non-availability at times of highest patient demand. GPs' reasons for working in A&E sometimes differed from the aims of primary care in an A&E service. Staff interviews revealed differing views about their role and about use of triage protocols. Ethnicity data were being collected, but not yet being used, to improve service to patients. CONCLUSIONS: A number of benefits follow the introduction of primary care practitioners into A&E. Different models have evolved, with a variety of GP and NP staffing arrangements according to local ideas and priorities. There is some confusion over whether these services aim to improve A&E-based care or to divert it to general practice. Cost information is inadequate so far, though the use of GPs has shown the possibility of economy. Appropriate location of services requires clearer identification of costs. This may be possible for the proposed primary care groups.

Disease prevention and health promotion: a study of medical students and teachers.

All students at the Royal Free Hospital School of Medicine (n = 508) were surveyed on their self-reported smoking and drinking habits, attitudes to disease prevention and health promotion in general, attitudes towards the teaching of disease prevention and health promotion, and their perception of what was taught at the beginning of the 1993-1994 academic year (response rate 75.2%). The teaching staff (n = 271) were also surveyed on their attitudes towards the teaching of disease prevention and health promotion, and their perception of what was taught (response rate 74.2%). Seventeen per cent of the students reported they were current smokers and 81% drank alcohol. Four factors were extracted from the responses to the items on disease prevention and health promotion in general and these represented the importance of health, a patient-centred approach, patient responsibility and a doctor-centred approach. Clinical students and those who were older were more likely to have a 'patient-centred' approach to disease prevention and health promotion. Sixty per cent of clinical and 44% of pre-clinical teachers aimed to teach about disease prevention and health promotion. The topics reported by students as most likely to have been taught in detail are smoking and health, alcohol and health, immunization, and breast and cervical screening. However, all these topics were reported as having been taught in detail by less than 50% of the students. The majority of students and teachers believe that teaching about disease prevention and health promotion should be integrated into all years of the curriculum and all clinical firms. Teachers were significantly less likely than students to believe that students should learn more about disease prevention and health promotion, and that learning about prevention is as important as learning about diagnosis and treatment. We believe that, in order to build on the positive features highlighted in this study, agreed aims and objectives should be developed and teaching about disease prevention and health promotion should be integrated both horizontally and vertically throughout the curriculum.