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Results for “Bone Demineralization, Pathologic”

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PubMed1999

Bone mineral density of the proximal femur after unilateral cementless total hip replacement.

It was the aim of this study to examine bone mineral density changes in the non-operated contralateral femur of patients undergoing total hip replacement. Bone density in the contralateral femur of 45 patients with an average age of 54 years was measured with the aid of the DEXA technique at one week, 3 and 6 months after total hip replacement. Within the first 3 months there was an average reduction of bone density of 3.9% (3.0%-5.9%). After a further 3 months the average difference was 2.5%.

Absorptiometry, Photon↗
PubMed2004

Bone loss in the contralateral asymptomatic hand in patients with complex regional pain syndrome type 1.

Regional osteoporosis was seen radiographically in clinically affected areas in patients with complex regional pain syndrome type 1 (CRPS1). The aim of the this study was to investigate whether bone loss developed in the contralateral hand in patients with unilateral CRPS1 of the hand. Thirty-two patients with CRPS1 of the hand were included in this study. Bone mineral density was measured in the left proximal femur and both ultradistal radiuses, using dual-energy X-ray absorptiometry. The subjects were classified as grades 1 to 3 according to the T-score of both ultradistal radiuses (densitometric grades): grade 1, both radiuses were normal; grade 2, bone loss was determined only in the affected radius; and grade 3, there was bone loss in both radiuses. Twenty (62.5%) patients had bone loss in the affected hand; 11 patients (34.4%) had bone loss only on the affected side and 9 patients (28.1%) had bone loss on both sides. The mean duration of the period between the diagnosis of the injury and the measurement of bone density was 1.9 +/- 0.6 months in patients with grade 1, 3.1 +/- 1.0 months in patients with grade 2, and 5.5 +/- 2.2 months in patients with grade 3. The Spearman test showed a significant correlation between the period of injury and the densitometric grade ( R = 0.774; P = 0.0001). In conclusion, the current study of patients with CRPS1, showed that the bone loss in the asymptomatic contralateral hand developed at a later stage than that in the affected hand. This bone loss was less frequent and of a lower degree in the asymptomatic contralateral hand than in the affected hand. The bone loss in the asymptomatic contralateral hand could be explained by the loss of sympathetic tone in CRPS1 and contralateral sympathetic innervation.

Absorptiometry, Photon↗
PubMed1998

Factors influencing lumbar spine bone mineral density assessment by dual-energy X-ray absorptiometry: comparison with lumbar spinal radiogram.

A study was conducted to determine the effect of radiographic findings of lumbar spinal changes upon bone mineral density measurements obtained by dual energy X-ray absorptiometry (DXA). Four hundred subjects were chosen from among 1543 community residents, aged 40-79 years. Study groups of 50 subjects each were selected by sex and 10-year age groups. This study investigated 390 of the 400 subjects who agreed to the conduct of spine bone mineral density measurement and spinal radiography. Lumbar spine radiograms were examined for findings of osteophyte formation, facet joint osteoarthritis, vertebral fracture, and aortic calcification. The prevalence of osteophyte formation, facet joint osteoarthritis, vertebral fracture, and aortic calcification increased with age in both men and women. On multiple regression analysis, bone mineral density was significantly higher (P < 0.001) in subjects with osteophyte formation or facet joint osteoarthritis than in those without these conditions, while bone mineral density was significantly lower in subjects with vertebral fracture. This study demonstrated that osteophyte formation, facet joint osteoarthritis, and vertebral fracture should be taken into account in the evaluation of bone mineral density by DXA in people in older age groups, since these conditions occur at a considerable rate in such subjects.

Absorptiometry, Photon↗
PubMed2002

Bone mineral density in adolescent girls with anorexia nervosa--a cross-sectional study.

UNLABELLED: The total body and lumbar spine bone mineral density (BMD) were measured in order to determine the prevalence and possible risk factors of decreased BMD in anorexia nervosa (AN). SUBJECTS: Sixty-one in-patient girls with DSM III-R AN: age 14.7+/-2.16 years; duration of AN 12.9+/-15.1 months; percentage of ideal body weight 70+/-8.7%; body mass index score -1.62+/-0.79. METHOD: Total body (in 61 patients) and lumbar spine BMD (in 43 patients), content of lean and fat tissue mass were measured by DXA during the first month of treatment. RESULTS: Low total body BMD was found in 23.7% and low lumbar spine BMD in 36.6% of patients. There was a negative correlation between BMD and age, age of menarche, degree of undernourishment, duration of AN and amenorrhea. A step-wise linear regression analysis revealed that age of menarche was the most important factor related to BMD in this group.

Absorptiometry, Photon↗
PubMedDate not supplied

The effects of hypokinesia in primates on bone strength.

A 14 days ground based primate hypokinesia investigation was conducted to determine what changes, if any, in bone strength may be demonstrated following 2 weeks cast immobilization and at 14 davs after removal from casts. Controlled compressive loads were applied to vertebral bodies excised from control, 2 weeks immobilization and 2 weeks post immobilization Rhesus monkeys. The material properties reported herein are ultimate load, displacement to ultimate load, stiffness and energy to ultimate load. These results show a decrease in bone strength following immobilization and a still further decrease in bone strength after 14 days.

Animals↗
PubMedDate not supplied

Bone effects of space flight: analysis by quantum concept of bone remodelling.

During the manned Skylab flights mineral losses from the calcaneum and changes in external calcium balance were in the ranges found for healthy subjects at bedrest. Calcium balance reached a nadir of -200 mg/day by two months with no change thereafter; the negative balance was due to increased urinary excretion with no change in net absorption. The total calcium loss averaged 18 g in the longest flight of 84 days; the densitiometric data suggested that about two-thirds of this came from trabecular bone and about one-third from cortical bone. These data could represent reversible bone loss due to increased birth rate of normal osteoclasts and osteoblasts and consequent increase in bone turnover and in reversible mineral deficit, or irreversible bone loss due to overactive osteoclasts and/or underactive osteoblasts. If the former explanation is correct, significant bone loss is unlikely whatever the duration of future flights, except in older persons already losing bone; if the latter explanation is correct, space flights longer than six months may lead to a significant increase in fracture risk in later life. Neither terrestrial immobilization nor unwilling animals in orbit are ideal models for the effects of space flight on human bone. To choose between reversible and irreversible mechanisms of bone loss, and to determine the effects of space flight on lifelong fracture risk, future astronauts and cosmonauts must undergo adequate histologic study of bone after in vivo tetracycline labeling.

Absorptiometry, Photon↗
PubMed1989

Mineralization of human bone tissue under hypokinesia and physical exercise with calcium supplements.

It has been suggested that physical exercise and calcium supplements may be used to prevent demineralization of bone tissue under hypokinesia (diminished muscular activity). Thus, the aim of this study was to determine mineral content of bones of 12 physically healthy men aged 19-24 years under 90 days of hypokinesia and intensive physical exercise (PE) with calcium lactate (C) supplements. They were divided into experimental and control groups with 6 men in each. The experimental group of men were subjected to hypokinesia (HK) and intensive PE and took 650 mg C 6 times per day; the control group was placed under pure HK, i.e. without the use of any preventive measures. The mineral content of different bone tissues was measured with a densitometric X-ray method in milligrams of calcium per 1 mm3 before and after exposure to HK. The level of bone density of the examined bone tissues decreased by 7-9% and 5-7% for the control and experimental groups of men, respectively. A statistical analysis revealed that the reduction of bone mineralization was significant with P < 0.01 in both groups of men. A comparison between bone density changes in the control and experimental groups of men failed to demonstrate significant differences. It was concluded that the level of mineralization of bone tissues decreased under hypokinesia and physical exercise with calcium supplements.

Adult↗
PubMed1991

Effect of hyperhydration on bone mineralization in physically healthy subjects after prolonged restriction of motor activity.

The objective of this investigation was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on bone mineralization in physically healthy male volunteers after exposure to hypokinesia (decreased number of steps taken/day) over a period of 364 days. The studies were performed after exposure to 364 days of hypokinesia (HK) on 18 physically healthy male volunteers who had an average VO2max of 65 ml/kg/min and were aged between 19 and 24 years. For the simulation of the hypokinetic effect the volunteers were kept under an average of 1000 steps/day. The subjects were divided into three equal groups of 6: 6 underwent a normal ambulatory life (control group), 6 were placed under HK (hypokinetic group) and the remaining 6 were subjected to HK and consumed a daily FSS (water 26 ml/kg body wt and NaCl 0.10 mg/kg body wt) (hyperhydrated group). The density of the ulnar, radius, tibia, fibular, lumbar vertebrae and calcenous was measured. Calcium and phosphorus changes, plasma volume, blood pressure and body weight were determined. Calcium content in the examined skeletal bones decreased more in the hypokinetic subjects than in the hyperhydrated subjects. Urinary calcium and phosphorus losses were more pronounced in hypokinetic than hyperhydrated subjects. Plasma volume and body weight increased in hyperhydrated subjects, while it decreased in hypokinetic subjects. It was concluded that a daily intake of FSS may be used to neutralize bone demineralization in physically healthy subjects during prolonged restriction of motor activity.

Adult↗
PubMed1991

Effect of fluid and salt supplements in preventing the development of "osteopenia" in hypokinetic rats.

It has been suggested that a daily intake of fluid and salt supplements may be used to prevent bone demineralization in human subjects after prolonged exposure to hypokinesia (diminished muscular activity). Thus, the objective of this investigation was to evaluate the effect of fluid and salt supplementation in the prevention of development of osteoporosis in 64 Wistar rats with an initial body weight of 339-345 g, after exposure to 90 days of hypokinesia. They divided into 4 equal groups: the first group of rats placed under ordinary vivarium conditions and served as vivarium control; the second group were also placed under ordinary vivarium conditions but received daily fluid and salt supplements; the third group were subjected to pure hypokinesia, i.e. without the use of any preventive measures; and the fourth group were submitted to hypokinesia and received daily fluid and salt supplements. For the simulation of the hypokinetic effect the experimental group of rats were kept in small, individual, wooden cages. Through the experimental period the second and fourth group of rats received 8 ml/100 g body wt water and 5 ml 100 g body wt NaCl daily. By the end of the experimental period the animals were decapitated and the spongy matter of tibia and vertebrae of the rats were examined for changes referable to osteoporosis. It was found that the daily intake of fluid and salt supplements caused an increase in the volume density of primary spongiosa of bones. It was concluded that a daily intake of fluid and salt supplements may be used to prevent the development of osteoporosis in rats subjected to prolonged motor activity restriction.

Animals↗
PubMed1991

The state of human bone tissue during space flight.

The results of studying the bone tissue of cosmonauts after the flights (4-8 month) have been compared to the data of investigating the healthy individuals during head-down tilt (HDT, 370 days). Noninvasive methods (computer tomography, gammaphoton absorptiometry) revealed a decrease in the vertebral spongy mineral density or a increase of this parameter by a similar magnitude versus the individual preflight values in some cosmonauts. During studies of clinical cases of osteoporosis it was shown that the vertebral mineral density ratios and presence or absence of vertebral compression fractures in different age groups are nonequal.

Absorptiometry, Photon↗
PubMed1992

Non-invasive densitometry.

Several non-invasive methods are available to measure bone density in different regions of the skeleton. Bedrest and microgravity both lead to bone loss, which is more marked in the lower parts of the skeleton. The bone loss can be monitored by non-invasive techniques in longitudinal studies when precision (i.e. the ability to produce repeated measurements with the same value) is adequate. Bone mineral density (BMD) can be measured with single photon absorptiometry in the lower forearm and calcaneus and with dual energy X-ray absorptiometry (DXA) in almost any region of the skeleton. The latter technique pairs good precision with very low radiation exposure. With peripheral quantitative computed tomography very precise measurements of the lower forearm and tibia are feasible with low radiation dose. It has the additional option of separate measurement of cortical and trabecular bone. This could be of particular importance in microgravity studies, as trabecular bone loss is more severe in this condition. A new development is the measurement of ultrasound velocity or attenuation which depends on bone density and structure. Ultrasound data of the calcaneus correlate well with bone mineral density in spine and hip. The advantage of this technique is that it operates without radiation. However, the clinical value has to be established. The ultimate choice of technique and skeletal region for bone densitometry will depend on specific requirements.

Absorptiometry, Photon↗
PubMed1992

Countermeasures against space flight related bone loss.

This paper reviews human data concerning bone loss and attempted countermeasures during spaceflight and bed rest, a commonly employed technique to simulate the effects of weightlessness on the musculoskeletal system.

Bed Rest↗
PubMedDate not supplied

Bone and body mass changes during space flight.

Body mass, calcium and skeletal changes occur in humans who have worked in microgravity. Physiologic changes are seen as early as one week and are still occurring 312 days into space flight. The physiologic changes in bone and mineral metabolism may be among those which limits long duration space flight if an adequate countermeasure is not developed. The purpose of this paper is to summarize what is known about calcium dynamics and bone mineral changes as well as associated changes of body mass induced by space flight. The data reported is from a variety of studies conducted in both actual and simulated space flight.

Aerospace Medicine↗
PubMed1989

Microgravity and musculoskeletal system of mammals.

This review surveys data in the literature and our own findings concerning the effects of weightlessness on bones and muscles of white rats flown on Cosmos biosatellites and Spacelab-3. It has been shown that the magnitude and sign of functional changes in muscles depend on their biomechanical profile. Structural and metabolic foundations of functional adaptation and its dynamics have been identified: in 5-7 day flights muscle contractility changes are mainly associated with a diminished activity of excitation-contraction coupling, in longer-term flights they are produced by changes in myosin populations specific for myofibers of different functional profile. At early flight stages (up to 1 week) osteoporosis and bone demineralization are very mild; therefore decrease in bone mechanical strength may be caused by changes in physico-chemical parameters of the collagen-crystal system. In flights of up to 3 weeks noticeable osteoporosis develops which is primarily produced by osteogenesis inhibition and which is responsible for a marked decrease of bone strength. These changes may result from uncoupling of bone resorption and remodelling processes. This uncoupling is characterized as incomplete osteogenesis and may be caused by changes in the collagen composition of the organic bone matrix. The above-mentioned adaptive changes in muscle functions of specific skeletal compartments may play a role in different responses of various bones to weightlessness.

Adaptation, Physiological↗
PubMed1994

Terrestrial applications of bone and muscle research in microgravity.

Major applications to people on Earth are possible from NASA-sponsored research on bone and muscle which is conducted either in microgravity or on Earth using models mimicking microgravity. In microgravity bone and muscle mass are lost. Humans experience a similar loss under certain conditions on Earth. Bone and muscle loss exist on Earth as humans age from adulthood to senescence, during limb immobilization for healing of orthopedic injuries, during wheelchair confinement because of certain diseases, and during chronic bed rest prescribed for curing of diseases. NASA-sponsored research is dedicated to learning both what cause bone and muscle loss as well as finding out how to prevent this loss. The health ramifications of these discoveries will have major impact. Objective 1.6 of Healthy People 2000, a report from the U.S. Department of Health and Human Services, states that the performance of physical activities that improve muscular strength, muscular endurance, and flexibility is particularly important to maintaining functional independence and social integration in older adults. This objective further states that these types of physical activities are important because they may protect against disability, an event which costs the U.S. economy huge sums of money. Thus NASA research related to bone and muscle loss has potential major impact on the quality of life in the U.S. Relative to its potential health benefits, NASA and Congressional support of bone and muscle research is funded at a very low level.

Adult↗