Running speed and spinal shrinkage in runners with and without low back pain.

Decreases in stature (shrinkage) are used to indicate exercise induced spinal loading. This study examined the effect of three running speeds on two groups of runners, one with chronic low back pain. The two groups of seven male marathon runners ran at 70%, 85%, and 100% of their marathon race pace for 30 min on separate occasions. Before and after exercise the subjects were seated for 20 min with the lumbar spine supported. Stature was measured before pre-exercise sitting, before running, after 15 min of running, after 30 min of running, and after post-exercise sitting. A stadiometer accurate to within 0.5 mm was used to record changes in stature. Results showed no differences in response to the three running regimens between the groups (P greater than 0.05). Shrinkage was greater during the first 15 min, being 3.26 (+/- 2.78) mm compared with 2.12 (+/- 1.61) mm for the second 15 min of the run (P less than 0.05). The faster the running speed the greater the resultant shrinkage. The 70%, 85%, and 100% conditions caused 3.37 (+/- 2.38), 5.10 (+/- 1.90), and 7.69 (+/- 3.69) mm of shrinkage, respectively (P less than 0.005). These results suggest that low back pain is independent of the shrinkage induced by running. Further research is required to determine the effect of longer duration runs on spinal shrinkage.

Changes in stature following drop jumping and post-exercise gravity inversion.

Spinal shrinkage, measured by changes in stature, is used as an index of spinal loading as alterations reflect changes in intervertebral disc height. Shrinkage induced by various physical activities may be reversed using gravity inversion. The present purpose was to examine the shrinkage induced by a drop jumping regimen and evaluate gravity inversion post-exercise. Eight males, aged 20-31, performed two separate experimental protocols, each on different dates at 1400 h. Subjects stood for 30 min before undertaking an exercise regimen, consisting of five sets of five drop jumps from a height of 1 m, rebounding over a hurdle 0.5 m high. For 20 min, directly following the exercise regimen, subjects on one occasion stood and on a second occasion undertook gravity inversion. Shrinkage was monitored for 40 min after this post-exercise treatment. The stadiometer used to measure shrinkage was accurate to 0.05 mm. The exercise regimen caused a mean shrinkage of 1.68 and 1.81 mm for the two testing sessions. Post-exercise inversion and standing for 20 min increased stature by 5.18 and 0.76 mm, respectively (P less than 0.01). The 40-min standing period following inversion caused a rapid loss in stature (4.07 mm). At 30 min into this recovery period, there was no significant difference in shrinkage for either of the regimens. Results suggest that effects of an inversion treatment are short-lasting.

Circadian variation in human stature.

The aim of this study was to monitor the creep in stature due to compression and its recovery over 24 hr in eight adult males. Measurements of stature were made at nine times during the 24-hr cycle using a purpose built metal frame tilted 5 degrees to the vertical. Accessories for standardization of posture and prevention of unwanted muscular tension included a series of microswitches on the frame, cross-beams for controlling spinal curvatures, slit spectacles used in conjunction with a mirror for proper head alignment. A dead load BAYE micrometer recorded stature to 0.01 mm. A significant circadian rhythm was established, the trough to peak variation being 19.3 mm or 1.1% of overall stature. Peak stature was measured at 0730 on awakening and the trough occurred at midnight before assuming a recumbent posture for sleep. Altogether 71% of the height gained during the night was achieved in the first half of the night's sleep. Over 50% of the height loss in a day was lost within the first hour of rising, 80% being lost within 3 hr of arising: the rate of creep decelerated throughout the remainder of the waking day. It is concluded that the rate of change in creep throughout the day varies, being greatest in the morning whilst distension is most pronounced in the early hours of sleep.

Biomechanical considerations in the straight-leg-raising test. Cadaveric and clinical studies of the effects of medial hip rotation.

Studies of the sacral plexus have been made in six cadavers to demonstrate the increased tension due to medial hip rotation. A standard protocol was adopted for the straight-leg-raising test (SLR) and three qualifying tests--dorsiflexion of the ankle, medial hip rotation, and cervical flexion--when examining 442 patients. Positive signs on medial hip rotation were frequently associated with evidence of increased tension and neurologic dysfunction of lumbosacral roots. It is concluded that uncontrolled hip rotation reduces the value of the SLR is a useful qualifying test for increased root tension, and that the diagnostic value and repeatability of SLR would be improved by adopting a standardized protocol.

1990 Volvo Award in clinical sciences. Lumbar spinal pathology in cadaveric material in relation to history of back pain, occupation, and physical loading.

The occurrence of symmetric disc degeneration, anular ruptures, end-plate defects, vertebral body osteophytosis, and facet joint osteoarthrosis was examined radiographically and osteologically in 86 male cadavers for whom occupational, physical loading, and back pain histories were obtained from the men's families. History of back pain and the parameters of spinal pathology were related to the highest and lowest degrees of physical loading. In multivariate analyses, history of back injury was related to the occurrence of symmetric disc degeneration, anular ruptures, and vertebral osteophytosis. Symmetric disc degeneration was associated with sedentary work, and vertebral osteophytosis was related to heavy work. History of back pain was related to occupational physical loading after control for the effects of the other covariates. The results indicate that the least pathology stemmed from moderate or mixed physical loading, but the least back pain was associated with sedentary work.

Circadian variation in stature and the effects of spinal loading.

Using a method comparable with that of Eklund and Corlett (1984) stature was measured with an accuracy of I mm in eight young adults. The mean circadian variation was 19.3 mm (1.1% of stature). Fifty-four percent of the diurnal loss in stature occurred in the first hour after rising. Approximately 70% was regained during the first half of the night. With static shoulder loads (2.5-40 kg), increases in the rate of shrinkage with increasing weight were nonlinear. Repetitive lifting led to greater shrinkage than with equivalent static loading. Rest in Fowler's position gave more rapid regains in stature than post-exercise recovery in standing positions. The technique is therefore suitable for assessment of the effects of manual work with both occupational and therapeutic applications.

Plain radiographic, discographic, and direct observations of Schmorl's nodes in the thoracolumbar junctional region of the cadaveric spine.

The perceivability of Schmorl's nodes in plain radiographs and discograms in the thoracolumbar junctional region (T10-L1) of the cadaveric spine was assessed by comparing the radiologic measurements with bone measurements. Schmorl's nodes in bone specimens were encountered in 19 of 24 spines studied. They were more than two times as common between vertebrae T10-11 and T11-12 as between T12 and L1 (P less than 0.01). When the areas of actual Schmorl's nodes exceeded 0.5 cm2 (corresponding to an aperture with a diameter of 0.8 cm), 47% of the nodes were seen in plain lateral radiographs and 68% in discograms. When the area measured 0.5 cm2 or less, only 24% could be perceived in plain lateral radiographs and 23% in discograms. The clinical significance of Schmorl's nodes remains uncertain as long as they are difficult to detect in vivo.

Facet joint orientation, facet and costovertebral joint osteoarthrosis, disc degeneration, vertebral body osteophytosis, and Schmorl's nodes in the thoracolumbar junctional region of cadaveric spines.

The disc degeneration in the thoracolumbar junctional region (T10-L1) of 37 male cadaveric spines was recorded with the use of discography. From 24 of these spines the facet joint orientation and degenerative findings of the facet and costovertebral joints, vertebral bodies (osteophytosis) and discs, and Schmorl's nodes were recorded directly from bones. At T11-12, the most common site for the transitional zone between thoracic and lumbar facet type, there was a marked variation in the orientation of facets. The occurrence of degenerative findings and Schmorl's nodes at the three levels in the region differed. At T10-11, disc degeneration, vertebral body osteophytosis, and Schmorl's nodes were most common (anterior degeneration). At T12-L1, facet and costovertebral joint degeneration were dominant (posterior degeneration). At T11-12, disc degeneration, vertebral body osteophytosis, Schmorl's nodes, and facet and costovertebral joint degeneration all occurred (anterior and posterior degeneration). The results point to a pathoanatomic association between degenerative changes and facet orientation.

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.

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.

Radiographic measurements of lumbar spinal canal size and their relation to back mobility.

A total of 197 men and women with history of previous back pain were radiographed and clinically examined. Measurements related to the shape and size of the spinal canal were subsequently made from the lumbar radiographs. Interarticular distance and the ratio between interarticular and interpedicular distances were significantly less in women with restriction of lumbar extension, sidebending, and rotation: not in men. Anteroposterior (AP) foraminal distances and pedicular lengths were less in men with restricted extension and sidebending, although not in women. Midsagittal diameters were not significantly less in those with restricted mobility. The radiographic differences between men and women with restricted back mobility arise partly from the sexual differences in interarticular and AP foraminal distance, the former being less in women, the latter in men. This suggests a different pathogenetic factor in the two sexes.

Back pain in industry. A prospective survey.

Eight hundred and two subjects employed in N.W. England have been interviewed and examined after episodes of back or sciatic pain, using a standardized procedure. Data on recurrence of symptoms leading to further treatment or absence from work in the following two 12-month periods were obtained by postal questionary. Residual pain in the leg and a number of positive clinical signs of return to work, longer sickness--absence for the current attack, and two or more previous attacks were all associated with recurrence or persistence of symptoms. The prognosis also varied according to the cause of back pain, falls being associated not only with longer periods of absence in the current attack but with a higher rate of recurrence. The results have underlined the significance of a thorough examination on return to work after back pain for the industrial medical officer, as well as the epidemiological importance of this phase in the natural history of back and sciatic pain.

Radiographic vs. direct measurements of the spinal canal of the thoracolumbar junctional region (T10-L1) of the spine.

Midsagittal diameter (MSD) and interpedicular distance (IPD) in the thoracolumbar junctional region (T10-L1) of 24 male cadaveric spines were measured both from radiographs and directly from bones after removal of the soft tissues in order to assess the accuracy of plain radiographs. In addition surface areas of the vertebral canals were measured also from bone samples. It was found that the mean difference between bone and radiographic measurements in the IPD on different vertebral levels was 1.0 mm (r = 0.98). The MSD was a more difficult measurement, but the correlation coefficient was still 0.70, the mean difference being 0.7 mm or less. The sum of the MSD and IPD showed good relationship with the cross sectional area of the spinal canal, and the correlation coefficient was 0.77 (P less than 0.001).

1987 Volvo award in clinical sciences. The perception of back pain and the role of psychophysical tests of lifting capacity.

In order to study the predictive value of pre-employment screening tests, a volunteer population of 1,741 men and 1,150 women was questioned about their experience of low-back pain (LBP) and their perception of physical exertion at work. They undertook a battery of tests, including psychophysical assessments of lifting capacity, and they were followed up by postal questionnaire after 1 year. The response rate was 88.7%. The psychophysical tests have proved to be simple and inexpensive to administer; in good hands, they are repeatable. Although psychophysical lifting capacity was less in those with previous LBP, the psychophysical strength tests were poor predictors of future LBP. But when the previous history of LBP was known, then the test results significantly enhanced the prediction.

Herniated lumbar disc syndrome and vertebral canals.

Herniated lumbar disc or definite sciatica was diagnosed in 16 of 195 men and women who had reported a history of low-back pain in a health survey. Measurements related to the size and shape of the lumbar spinal canal were subsequently made from the survey radiographs and compared between various types of back syndromes. Age, body height, body mass index, occupation, and parity of women were controlled as potential confounders using analysis of covariance. Several dimensions of lumbar vertebral canals appeared more shallow in the subjects who had herniated disc or definite sciatica than in the other ones. In particular, the interarticular distance of the first sacral vertebra was found to be narrowed in the presence of sciatica, the difference of the adjusted distances to the other back pain category being in men 30.5 mm versus 35.1 mm (P = 0.02) and in women 23.8 mm versus 30.3 mm (P = 0.002), respectively.

The influence of age and gender on lumbar spine sagittal plane range of motion. A study of 1126 healthy subjects.

Inclinometers have been recommended for the measurement of lumbar spine range of motion (ROM) in the assessment of disability. Range of motion thresholds that determine impairment ratings have been established without regard to age and gender or variances of the measures. This investigation determined the effect of gender and age on lumbar spine sagittal plane ROM in 1126 healthy male and female volunteers. Results indicate that distinct differences exist between men and women in flexion angle and extension angle, whereas little difference exists between genders for total lumbar sagittal ROM. Total sagittal ROM, flexion angle, and extension angle declined as age increased. Because of the high degree of variability in the measurements, detecting impairment in ROM with this method is problematic.

Low-back pain in nurses and some loading factors of work.

Questionnaires were sent to qualified nurses (QNs) and nursing aides (NAs) to study the prevalence of low-back pain (LBP) and sciatica in relation to age, work-load, free time activities, menstruation, pregnancies and number of children. LBP and sciatica severe enough to make them unfit for daily tasks were significantly more common in NAs. Back injury and disability pension due to sciatic symptoms were also more common in NAs. Occupationally, NAs had twice the amount of lifting, bending, and rotation, while QNs reported more sitting and standing at work. Under the age of 30, the heaviness of the work was related to LBP in both NAs and QNs. It was concluded that prevention should be directed to improvements in the occupational work load, particularly for younger nurses.

Patient-handling skill, back injuries, and back pain. An intervention study in nursing.

The aim of this intervention was to evaluate the effect of training on patient-handling skills and prospectively to assess the effect of skill on subsequent back pain and back injuries in nursing. Of a total of 255 nurses, 199 were assessed for their skill in patient-handling. One-half (control group) received traditional training in patient-handling, and the other half (trained group) received a curriculum of instruction totaling 40 hours. The skills of both groups were assessed on graduation. The control group was rated as less competent in patient-handling. Nurses in both groups were questioned about the prevalence of back pain and incidence of back injuries in the first year after graduation. In multiple regression analysis, the major risk indicators for back injuries were poor patient-handling skill, low numbers of repetitions in the sit-up test, and high work-load scores. High score on the hysteria scale of Middlesex Hospital Questionnaire was a risk indicator for all kinds of back pain. Though back pain was independent of patient-handling skill, those rated as "bad" or "poor" had more back injuries (24%) than those who had been rated as "good" or "excellent" (2%) (P less than 0.001), but the difference between the trained and control groups was not statistically significant. It was concluded that back injuries may be prevented by the teaching of patient-handling skills.

The prediction of chronicity in patients with an acute attack of low back pain in a general practice setting.

STUDY DESIGN: Three hundred patients, attending their general practitioners with attacks of acute low back pain, formed the subject population for a study of fear avoidance and other variables in the prediction of chronicity. Follow-up was at 2 and 12 months. OBJECTIVE: The hypothesis to be tested was that evidence of psychological morbidity, particularly fear-avoidance behavior, would be manifest from the outset of the presenting attack in susceptible subjects. SUMMARY OF BACKGROUND DATA: While back pain is an almost universal human experience, only about 5% of sufferers seek medical advice. Most of these respond to conservative treatment. However, approximately 10% of those who experience an acute attack of low back pain go on to become chronic sufferers. METHODS: Psychosocial and physiological data (including fear-avoidance measures) were collected from a sample of 300 acute low back pain patients within 1 week of presentation and at 2 months, to try to predict 12 month outcome. RESULTS: Data analysis showed that subjects who had not recovered by 2 months were those who went on to become chronic low back pain patients (7.3%). Using multiple regression analyses, fear-avoidance variables were the most successful in predicting outcome. Using multiple discriminant function analyses, the results suggest that the outcome in terms of the future course of low back pain can be correctly classified in 66% from fear-avoidance variables alone and in 88% of patients from all variables. CONCLUSIONS: The results suggest that, at the earliest stage of low back pain, fear of pain should be identified by clinicians and, where this is severe, pain confrontation should arguably form part of the approach to treatment.

Causes, prediction and prevention of back pain at work.

Pain in the back and lower limbs due to lumbar disorders has a multifactorial etiology, and there is no clear relationship between the morbid pathological change observed and the symptoms experienced. Of the precipitating factors, unaccustomed heavy work, postural fatigue, and injury are common. "Back injury," however, embodies a variety of phenomena, few of which can readily be distinguished either in national statistical data or in previous epidemiologic studies. Thus the causal relationship between back pain and work is far from clear, a difficulty compounded by the prevalence of back symptoms in all groups of the population. There are few epidemiologically established methods for identifying people who are susceptible to a first attack of back pain, though, once back pain has been reported, recurrence may be predicted. Selection of the preventive approach depends on reliable information about the prevalence of back pain/discomfort, the back injury rate, sickness absence, etc; about accidents, work stoppages, job turnover, or any other pointers to the design of the workplace or work practices; and about the resulting losses of productivity and the costs of the remedy. Though the decisions are up to management, the quality of the information required is mainly an occupational health responsibility.