Incident fall risk and physical activity and physical performance among older men: the Osteoporotic Fractures in Men Study.

Physical activity and physical performance have been linked to fall risk in the elderly. The authors examined the relation between physical activity and physical performance with incident falls in the Osteoporotic Fractures in Men Study, a large prospective cohort study of 5,995 community-dwelling men in the United States at least 65 years of age. The authors also examined what types of activities are associated with falling. Incident falls between 2000 and 2005 were captured from up to 17 triannual follow-up questionnaires per participant and analyzed with generalized estimating equations. Follow-up averaged 4.5 years. The average risk of falling in the first 4 months of follow-up was 6.6%. The most active quartile had a significantly greater fall risk than did the least active quartile (relative risk = 1.18, 95% confidence interval (CI): 1.07, 1.29). Men with greater leg power and grip strength had significantly reduced fall risk (for highest leg power quartile vs. lowest: relative risk = 0.82, 95% CI: 0.73, 0.92; for highest grip strength quartile vs. lowest: relative risk = 0.76, 95% CI: 0.69, 0.85). Partitioning components of activity showed no association between fall risk and leisure activities but a positive association with household activities (for highest quartile vs.lowest: relative risk = 1.17, 95% CI: 1.07, 1.28).

Fracture healing: bone healing, fracture management, and current concepts related to the hand.

Bones fracture frequently and often result in significant impairments, functional limitations, and disabilities, especially when the hand is involved. When fractures occur, there is a disruption of the skeletal tissue organization and a loss of mechanical integrity. The goal of fracture healing is to regenerate mineralized tissue in the fracture area and restore mechanical strength to the bone. Of equal importance is the reconstitution of the normal soft tissue gliding and movement about the fracture site. This article briefly reviews the history of fracture healing and the advances in mechanics and cellular and molecular biology, which should help the reader better understand the current mechanisms related to bone healing (primarily and secondarily). Fracture fixation modes also are described along with the temporal sequencing as to when to protect or move the fractured region.

Seasonal interaction of serum vitamin D concentration and bone density in alpacas.

OBJECTIVE: To evaluate temporal changes in bone mineral density associated with seasonal variation in serum vitamin D, calcium, and phosphorus concentrations in alpacas. ANIMALS: 5 healthy mature neutered male alpacas. PROCEDURE: Metacarpal bone mineral density was measured at 4 times during a year. Each time alpacas were weighed, blood was collected for determination of serum calcium, phosphorus, and vitamin D concentrations, and samples of feed were analyzed for nutrient content. Vitamin D status was determined by use of an assay that measured serum 25-hydroxycalciferol concentration. Effects of changes in serum vitamin D, calcium, and phosphorus concentration and body weight with season on bone mineral density were determined. RESULTS: Bone mineral density, body weight, and serum vitamin D and phosphorus concentrations varied with season. Bone mineral density, serum vitamin D concentration, and body weight also varied among individual alpacas. Serum vitamin D concentration was lower in January than the previous October and increased from May to the following September. The decrease in bone mineral density lagged behind the decrease in serum vitamin D concentration and was lower in May, compared with the previous October. Body weight was lower in May than the previous October or following September. Solar radiation was highest in July and lowest in December. CONCLUSIONS AND CLINICAL RELEVANCE: Seasonal changes in bone mineral density are associated with changes in serum vitamin D concentrations in alpacas. Changes in bone mineral density associated with a decline in serum vitamin D concentration may predispose some alpacas to developing fractures minimal trauma.

Anthropometric estimation of bone mineral content in young adult females.

It was hypothesized that improved prediction of bone mineral content (BMC) would be achieved by an expanded battery of anthropometric variables beyond height and the four extremity diameters used by previous investigators to predict skeletal mass (r = 0.74). Accordingly, sitting height, trunk diameters, chest depth, and head circumference, as well as whole body BMC and bone mineral density (BMD) via dual-energy X-ray absorptiometry (DEXA), were also measured on 52 young adult females (26 each Blacks and Whites), aged 18 to 30 years. The product of height and the squared sum of four extremity breadths, utilized by previous investigators, resulted in r values of 0.74 and 0.70 for the Black and White groups, respectively. Separate stepwise multiple regressions to predict BMC for each group resulted in a collectively different array of independent variables (though there was some overlap between groups). The multiple regression formula for the Black group (R = 0.88; SEE = 156 g) included height, chest depth, chest diameter at the sixth rib level, and knee bicondylar diameter. That for the White group (R = 0.83; SEE = 193 g) included two diameters (bicondylar and biepicondylar) and head circumference. When anthropometrically estimated values for upper-arm muscle area or upper-leg lean tissue area (which were better correlated to BMD than BMC) were added to these equations, prediction of BMC was further improved (R = 0.91; SEE = 144 g; and R = 0.85; SEE = 187 g, respectively, for the Black and White groups). The major observation in this study was a substantial improvement in the predictive precision of BMC, as assessed by DEXA, via easily obtainable anthropometric data. Further, the SEE values in this totally anthropometric prediction of whole body BMC closely approximate that recently reported for adult females, aged 18-49 years, when including the mid-shaft radial BMC (assessed by single-photon absorptiometry) with height, weight, and body mass index. It is concluded that anthropometric estimation of BMC may be a potentially useful tool to improve the accuracy of percentage body fat estimation assessed by hydrostatic weighing, and that it should be examined in other populations differing significantly in fat-free mass density from the 1.10 g/ml value of the reference man. © 1992 Wiley-Liss, Inc.