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Biomedical subjects

A K Burton

Publications and source records attributed to A K Burton.

17 recordsLinked to original sources
PubMed1995

Psychosocial predictors of outcome in acute and subchronic low back trouble.

STUDY DESIGN: A prospective survey of patients seeking primary care for low back pain. Clinical and psychosocial data, available at presentation, were explored for predictors of outcome at 1 year. OBJECTIVES: To determine the relative value of clinical and psychosocial variables for early identification of patients with a poor prognosis. SUMMARY OF BACKGROUND DATA: Current treatment strategies for low back pain have failed to stem the rising levels of disability. Psychosocial factors have been shown to be important determinants of response to therapy in chronic patients, but the contribution from similar data in acute or subchronic patients has not been comprehensively investigated. METHODS: Two hundred fifty-two patients with low back pain, presenting to primary care, underwent a structured clinical interview and completed a battery of psychosocial instruments. Follow-up was done by mail at 1 year; outcome was measured using a back pain disability questionnaire. Predictive relationships were sought between the data at presentation and disability at follow-up. RESULTS: Most patients showed improved disability and pain scores, although more than half had persisting symptoms. Eighteen percent showed significant psychological distress at presentation. Multiple regression analysis showed the level of persisting disability to depend principally on measures in the psychosocial domain; for acute cases outcome is also dependent on the absence or presence of a previous history of low back trouble. Discriminant models successfully allocated typically 76% of cases to recovered/not-recovered groups, largely on the basis of psychosocial factors evident at presentation. CONCLUSIONS: Early identification of psychosocial problems is important in understanding, and hopefully preventing, the progression to chronicity in low back trouble.

Acute Disease↗
PubMed1994

Estimation of spinal loads in overhead work.

To explore the spinal loads occurring in overhead working postures and to assess the value of ergonomic reduction of lumbar extension, spinal strain was measured by stature change in simulated motor vehicle maintenance tasks. A field study identified the typical extent of lumbar extension incurred in this type of work. In the laboratory eight male volunteers tightened and loosened bolts both overhead and at chest-height for 30 min periods; records were made of lumbar posture, ground reaction force, and perceived exertion. Stature change was measured using a refined technique which permitted estimation of net effect of the work loads. The field study revealed that motor mechanics typically spent 8% of their time working overhead with up to 10 degrees of lumbar extension. In the laboratory study, the overhead task entailed more lumbar extension and perceived exertion than did the chest-height task; ground reaction forces did not differ substantially between tasks. Only small changes in stature were observed at the end of the work period, and there was no significant difference between the tasks (means: overhead, +0.61 mm; chest-height, -0.23 mm: p = 0.31). Stature change was significantly correlated with lordosis for overhead work such that increased lordosis (compared with chest-height work) was associated with relative stature gain. No evidence was found to indicate a need for ergonomic intervention in overhead work tasks so far as spinal loading is concerned. The lack of substantial change in stature from tasks perceived to involve moderately high levels of exertion was unexpected; it would appear that some elements of dynamic work tasks may have a relative unloading effect, and that lordotic postures reduce load on the spinal discs.

Biomechanical Phenomena↗
PubMed1991

Does leisure sports activity influence lumbar mobility or the risk of low back trouble?

In order to look for relationships between leisure sports activity and both low back trouble and back flexibility, 958 people, aged 10-84 years, were examined. Their history of low back trouble and leisure sports participation was recorded, together with measurements of maximal lumbar sagittal mobility. No evidence was found to suggest that the extent of sports participation either during childhood or as an adult was related to the development, frequency, or onset-age of low back trouble. Although sports participation was not associated with flexibility in schoolchildren, adults who had continued leisure sports for greater than 5 years showed relatively reduced lumbar mobility. On the basis of the results presented here, it is concluded that sporting pursuits at amateur/leisure level do not, in themselves, represent a major risk factor for low back trouble. On the contrary, it was found that adults typically continued leisure sports participation for some years after developing low back trouble. Sports participation, in general terms, is not contraindicated for those who have experienced low back trouble, but regular exercise does not apparently result in increased lumbar flexibility.

Adolescent↗
PubMed1991

Prediction of the clinical course of low-back trouble using multivariable models.

The inability to predict outcome in patients with low-back pain seriously impedes clinical trials and leads to inappropriate or unnecessary treatment. This prospective study investigated the value of multivariable mathematical models to predict the 1-year clinical course of 109 patients with low-back trouble (LBT). Discriminant analysis was used to determine predictive models for outcome groups at 1 month, 3 months and 1 year. The variables selected in the analyses were subsets of 29 items from a clinical interview at presentation. These included anamnestic features of the first episode as well as symptomatic details and results from clinical tests for the current spell. The derived models successfully discriminated outcome groups with estimates of sensitivity and specificity ranging from 63 to 99%. When models from one set of patients were tested for predictive accuracy by the application of them to a different set, nonrecovery and satisfactory improvement were predicted with a 76-100% success rate. The results affirmed the importance of considering combinations of interrelated variables for prediction and discrimination in LBT. This work has demonstrated that outcome can be predicted successfully by the use of mathematic models based just on presentation data. The ability to determine homogenous groups in respect to outcome is seen as an important aid to therapeutic research; further work will enable refinement of these models for general clinical use and for incorporation into computer-based interview systems.

Adult↗
PubMed1991

Noninvasive measurement of lumbar sagittal mobility. An assessment of the flexicurve technique.

The use of flexicurves to measure lumbar sagittal mobility was subjected to a series of reliability and validation experiments. Appropriate statistical methods were described and used to quantify intraobserver and intrasubject variability and to determine limits of agreement with measurements from radiographs. It was shown that the traditional use of correlation coefficients can produce misleading or inadequate information. The flexicurve technique had an intraobserver variability of 3-4 degrees of movement, was not significantly influenced by intrasubject variability, and provided measurements typically within 6 degrees of radiographic measurements. The data suggest that the flexicurve technique is less biased than the inclinometric method. These results demonstrate the use of suitable statistical methods to assess the clinical usefulness, or level of interchangeability, of spinal measurement instruments.

Biomechanical Phenomena↗
PubMed1990

Lumbar sagittal mobility and low back symptoms in patients treated with manipulation.

The relationship between lumbar sagittal mobility and symptoms was explored in a 1-year prospective study of 55 patients undergoing manipulative treatment. A significant increase in mean mobility was found to occur in the 1st month, together with a concomitant significant decrease in mean pain values; symptoms continued to decrease thereafter, but mobility remained unchanged. More detailed analysis of the data revealed that symptomatic improvement was as common in patients with unaltered or reduced mobility as it was in those who showed an increase; changes in mobility at 1 month had no predictive value for symptomatic status at 1 month or 1 year. It is concluded that if any benefits actually result from manipulative therapy they are not a direct function of increased overall lumbar sagittal mobility. It remains possible that manipulation may influence other mobility parameters, such as coupled motions, so future studies should be directed toward investigation of three-dimensional movement patterns.

Adult↗
PubMed1989

Is recurrent low back trouble associated with increased lumbar sagittal mobility?

The hypothesis that increased lumbar sagittal mobility constitutes a risk factor for recurrent low back trouble was tested in respect of two specific groups of subjects thought likely to display this phenomenon: young females reporting recurrent back pain, and middle-aged adults reporting recurrent or persistent sciatic symptoms. Lumbar flexibility was estimated from back surface curvatures by a validated technique which uses a flexicurve to record mobility in upper (T12-L4) and lower (L4-S2) lumbar regions. Mean mobility for young females (less than 40 years) with recurrent back pain was less, though not significantly so, than those without back trouble. A loss of mobility was also found in young males with recurrent trouble. However, it was a proportionally greater loss than that found in the females and was statistically significant. The mean mobility for middle-age adults with recurrent sciatic symptoms was significantly reduced compared to those without a history of back trouble. Whilst these results failed to support the general hypothesis, it remains possible that aspects of increased mobility not studied here, such as localized segmental instability or abnormal coupled motions, may be associated with an increased frequency of recurrent low back trouble.

Adolescent↗
PubMed1989

Variation in lumbar sagittal mobility with low-back trouble.

The influence of low-back trouble on lumbar sagittal mobility was explored in 958 individuals aged 10 to 84 years. Experience of low-back trouble was determined by questionnaire, and categorized as none, a previous history, or a current spell. Maximal mobility was estimated from flexicurve records of back surface curvature. The results for adults revealed that mean mobility values were reduced by both previous and current low-back trouble, particularly in the upper lumbar region, when compared with nonsufferers. Stepwise regression analyses showed that variation in mobility was best accounted for by the cumulative effects of age and sex. These variables accounted for approximately one-third of the variation in mobility: low-back trouble only accounted for an additional 1%. At the extremes of the range, both hypomobility and hypermobility were identified as risk indicators for low-back trouble. Relative hypermobility was not confined to subjects with no history of back trouble; some current sufferers had particularly high levels of mobility. Similarly hypomobility was found in nonsufferers as well as in those with back trouble. The data indicated that young adults (notably males) with previous low-back trouble may not recover their previous mobility on symptomatic resolution. The finding of hypermobility in current sufferers indicates that mobilization therapy may not be appropriate for such patients.

Adolescent↗
PubMed1989

Prediction of low-back trouble frequency in a working population.

This study was performed to estimate the discriminatory power of multiple combinations of risk indicators for the occurrence and recurrence of low-back trouble (LBT) in workers. Two categories of LBT provided groups for discrimination; 1) the presence or absence of LBT history, and 2) three patterns of recurrence characterized by the number of episodes (isolated, periodic, chronic). The risk indicators comprised data reflecting occupational and leisure demands on the back, measures of lumbar sagittal mobility, and anamnestic features of the first episode. Discriminant analysis was the statistical procedure used. The results showed that it was possible to find linear combinations of the discriminating variables that successfully allocated around two-thirds of the sample to the correct group. The presence of a history of LBT was predicted by the combined effect of increasing age and adult sports participation, but only in females did a heavier job contribute to such prediction. A reduction in risk was associated with lumbar flexibility and sports participation at school. Chronic LBT was more accurately identified than the two other groups; increasing age, a long initial spell, and an onset early in life were associated with increased likelihood of chronicity, while a report of symptoms being relieved by sitting reduced this risk. It is concluded that the occurrence and recurrence of LBT are related to combinations of risk indicators, and that it is imperative to consider the interactive effect of a multiplicity of factors in epidemiologic studies.

Adult↗
PubMed1985

Grip strength and forearm straps in tennis elbow.

Twenty-seven patients who presented with tennis elbow had their grip strengths measured without a forearm strap, with an elastic strap and with an inelastic strap. Of these 85% displayed an increased pain-free grip strength with one or both straps. The increase in pain-free grip strength was statistically significant for both types of strap (p less than 0.001) and the results showed no consistent difference between them. The possible mode of action is discussed.

Elasticity↗
PubMed1981

Back pain in osteopathic practice.

The case records of 5310 patients attending Registered Osteopaths were examined in this retrospective study. Analysis of the data revealed that over half presented with low back pain and were comparable to those normally seen in orthodox medical practice, except that their symptoms were of longer duration. The patients were generally examined in a conventional manner but it was not possible to identify specific diagnostic categories. The majority received one or more manual therapeutic techniques but 6% were rejected as unsuitable for treatment. The implications of the results for future research are discussed.

Adolescent↗