Spinal shrinkage in females: circadian variation and the effects of circuit weight-training.
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Biomedical subjects
Publications and source records attributed to J D Troup.
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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.
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.
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.
Measurements made from plain lumbar radiographs were used to compare the size and shape of the lumbar vertebral canals between various categories of occupation and work load among 77 men and 118 women with a history of low-back pain. The mean anteroposterior foraminal diameters proved to be wider in female farm workers than in other women, especially in the vertebra L3 (17.1 versus 15.4 mm). However, the men who did heavy manual work had smaller anteroposterior foraminal diameters than the men whose work involved less physical labor (difference at L5 9.4 versus 10.8 mm). Female farm workers were found to have shorter interarticular distances than females in other occupational groups. In the men who reported working in stooped postures or reported lifting and carrying heavy objects at work, the interarticular distances were wider than in men who had no such exposures.
Loading and unloading of luggage in an aircraft luggage compartment is carried out manually in uncomfortable working position. In this study, the loading work was analysed by surveying musculoskeletal symptoms, by recording the working postures and techniques at work, and by simulating the loading work in a mock-up of a DC-9 aircraft compartment. Low back, knees and shoulders were exposed to mechanical load in luggage handling. Video recordings were used to analyse posture and work technique. In the simulated luggage compartment in the laboratory, ground reaction forces, intra-abdominal pressure (IAP) and electromyography (EMG) signals from back and shoulder muscles were recorded simultaneously. Loading in sitting, squatting and kneeling were the postures that were used the most often. Unloading was generally less stressful than loading, involving less static work. Handling time was shortest when kneeling but knee symptoms were dominant. Lateral ground reaction forces and EMG activity from trapezius were highest when sitting, and IAP peaks were greatest when squatting. Thus each posture had major, though differing, disadvantages and a radical redesign of the DC-9 luggage compartment was clearly indicated.
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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.
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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.
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.
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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.
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.
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