Minimizing errors associated with calculating the location of the helical axis for spinal motions.

One of the more common comparative tools used to quantify the motion of the vertebral joint is the orientation and position of the (finite) helical axis of motion as well as the amount of translation along, and rotation about, this axis. A survey of recent studies that utilize the helical axis of motion to compare motion before and after total disc replacement reveals a lack of concern for the relative errors associated with this metric. Indeed, intrinsic algorithmic and experimental errors that arise when interpreting motion tracking data can easily lead to a misinterpretation of the changes caused by replacement disc devices. While previous studies examining these errors exist, most have overlooked the errors associated with the determination of the location of the helical axis and its intersection with a chosen plane. The purpose of the study presented in this paper was to evaluate the sensitivity and reliability of the helical axis of motion as a comparative tool for kinematically evaluating spinal prostheses devices. To this end, we simulated a typical spine biomechanics testing experiment to investigate the accuracy of calculating the helical axis and its associated parameters using several popular algorithms. The resultant data motivated the development of a new algorithm that is a hybrid of two existing algorithms. The improved accuracy of this hybrid method made it possible to quantify some of the changes to the kinematics of a spinal unit that are induced by distinct placements of a total disc replacement.

Morbidity data collection in general practice: experience in the South Eastern Health Board 1998-1999.

A joint project between general practitioners and the South Eastern Health Board resulted in the establishment of a network of computerised practices collecting morbidity data in 1998 - 1999. Five practices established age sex registers for public and private patients. The International Classification of Primary Care 2 (ICPC-2) was used to define inclusion criteria for a range of illnesses relevant to primary care and public health. Problems arose in validating and extracting data in three practices. Disease prevalence for 17 illnesses was established for two practices only. The project clearly established the problems associated with morbidity data collection in general practice which include absence of a national patient registration system, absence of a national electronic messaging standard, difficulties extracting data from practice software systems and the need for a high level of dedicated staff and resources to implement such a project.

A comparison of fixed and disposable head Heaf guns.

The objective of the study was to compare the newly introduced Model 2000 disposable-head Heaf gun with the currently used fixed-head gun. The study simultaneously Heaf-tested 1410 school children on both forearms using a different gun on each arm; the tests were read blind. The results were similar for both Heaf guns. The fixed-head gun gave a stronger reaction in 202 (14%) children by one Heaf grade. The disposable head gun gave a stronger reaction in 116 (8%) children, by one Heaf grade in 113 and 2 Heaf grades in 3 children. kappa = 0.607 (95% confidence interval [CI] = +/- 0.038), indicating good agreement between the tests. chi 2 = 0.177, d.f. = 1, P = 0.7 NS. Given the practical advantages of Heaf skin testing for primary screening, it is likely that practitioners will replace the fixed-head gun with one that avoids sterilisation problems. The small variation between the tests was not considered clinically important, while the advantages of the new test were considerable. It is therefore recommended that the Model 2000 Heaf gun replace the fixed-head gun for primary screening.

A geographical distribution of mortality and deprivation.

Because of the paucity of data on the geographical distribution of mortality and deprivation in the Republic of Ireland, we calculated SMRs for each county for the years 1982-6. Two measures of mortality were used, all cause and avoidable mortality. Two indexes of deprivation were also calculated for each county, Townsend's and a new Irish index. Significant differences in mortality exist between counties. Counties that had SMRs significantly below the national standard of 100 were Meath, Donegal and Galway. Counties with significantly high SMRs were Louth, Limerick and Westmeath. County SMRs were correlated with both deprivation indexes and no significant correlation was found to explain the apparent differences in mortality.

The Kilkenny Post-Primary Schools Survey--a survey of knowledge, attitudes and behaviour relevant to non-communicable diseases.

This survey was carried out in the Spring of 1987 on a stratified random sample of 445 post-primary schoolpupils in County Kilkenny, Ireland. Knowledge, attitudes and behaviour relevant to non-communicable diseases were examined using a questionnaire developed from a World Health Organization core questionnaire. The results showed that levels of adolescent alcohol and tobacco use were similar to those found in neighbouring European countries. Smoking and drinking increased during adolescence and were more prevalent in males. Physical activity decreased throughout adolescence and a high intake of "snack foods" was found. Health-related knowledge levels were high but were not related to behaviour.

Trends in mortality from cardiovascular diseases in Ireland.

Trends in mortality from cardiovascular diseases in Ireland from 1950 to 1986 are examined and compared with trends in some other developed countries. There was a decline in mortality from all causes which was greater in women than in men. Mortality from coronary heart disease (CHD) increased in males from 1953 to 1974 and has been declining slowly since. Mortality rates in men in Canada and the United States are now lower than those in Ireland and rates in Finnish men are approaching those in Ireland. CHD mortality in Irish males was sixth highest of developed countries in 1985. In women, CHD mortality declined in the 1950s, was stable in the 1960s and early 1970s and has been decreasing slowly since 1974. CHD mortality in Irish women was fifth highest of developed countries in 1985. Mortality rates from cerebrovascular disease have been falling in Irish women since 1958 and in men since 1969. The continuing high mortality from CHD in Ireland warrants the establishment of effective community prevention programmes.