The relationship between fluoride and skeletal strength and fractures ispoorly understood. Recent ecologic studies have suggested that exposureto fluoridated water supplies may be associated with an increasedfrequency of hip fractures, but such studies have considerable potentialfor error in assessing fluoride exposure. Few Americans consume onlybeverages from a single water supply for their lifetime; additionally, fluoride has only been added to water supplies in the US since the late1940s, and widespread fluoridation only became common in the 1960s. MostAmericans included in these studies were only exposed to fluoride late inlife. However, these studies together with recent information fromtherapeutic trials using sodium fluoride have raised the possibility thatfluoride exposure may increase fracture risk excluding vertebralfractures. To address this issue we propose a study of fluoride exposureand fractures in a population with long-term stable exposures to fluoride. In rural China there is very little population mobility, andcorrespondingly little exposure to fluoride from sources outside the homevillage. We propose to: l identify 7,500 Chinese in 50-60 villages withwell-defined, long-term exposures to fluoride in a range of concentrationsbracketing l ppm, the 'optimal' level used in the US for fluoridation ofcommunity water supplies; 2 assess and confirm with x-rays and medicalrecords the adult fracture histories of these subjects, and determine therelationship between fracture prevalence at the village level and long- term fluoride exposure; 3 measure calcium intake, physical activityprimarily labor, and other factors potentially associated with bothfluoride exposure and fractures.Very little is known regarding the factors that affect the development ofpain and disability in those with radiographically establishedosteoarthritis OA of the knee. The primary aims of this study are toevaluate the contribution of weakness in the legs knee flexors andextensors: 1 to the development of symptomatic OA in those withasymptomatic radiographic evidence of OA; and 2 to the loss of functionand the progression to disability in those with symptomatic OA It hasbeen recognized for some time that x-ray evidence of OA of the knee withoutsymptoms is much more prevalent than symptomatic OA, suggesting thatfactors exist that determine whether or not joint changes becomesymptomatic. A variety of factors, including long-standing obesity, ahistory of trauma, and stiffer subchondral bone, have been suggested asrisk factors for OA; with the exception of weight loss which is difficultto maintain for long periods intervention on these factors is unlikely. In contrast, muscle strength is increasingly being recognized as analterable risk factor for various disorders associated with aging, including osteoporosis and falls. The public health implications of thesefindings and the possible importance of strength in OA arise primarily fromthree areas: 1 the frequencyof OA; 2 the established decline instrength, particularly lower extremity strength, with aging; and 3 thepotential for older people to increase strength using safe exerciseprograms over relatively short periods of time. We propose both cross-sectional and longitudinal studies of OA and musclestrength. Healthy adults over age 65 will be recruited from free-livingelderly and will undergo baseline assessments to determine: 1 thepresence of radiographic evidence of knee OA; 2 the presence of symptomsof OA; 3knee flexor and extensor strength. At the end of three years, these assessments will be repeated to determine: 1 the development ofsymptoms of OA; 2 changes in strength; 3 changes in radiographiccharacteristics. Between these two assessments, each subject will becontacted at six-month intervals to determine whether symptoms of knee OAhave developed.
Adipose Tissue, Aluminum, Arsenic, Body Composition, Body Density, Body Physical Activity, Bone Density, Bone Fracture, Cadmium, China, Dietary Calcium, Dosage, Environmental Contamination, Exercise, Fluorine, Functional Ability, Human Old Age, Human Population Study, Human Subject, Injury, Interview, Limb Movement, Longitudinal Human Study, Medical Record, Muscle Strength, Muscle Tone, Nutrition Related Tag, Osteoarthritis, Pain, Pathologic Process, Physical Property, Questionnaire, Radiography, Selenium, Social Support Network, Statistics Biometry, Stress, Trace Element, Water Supply, Water Treatment, X Ray
