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Biomedical subjects

Henrik G Ahlborg

Publications and source records attributed to Henrik G Ahlborg.

11 recordsLinked to original sources
PubMed2006

A school curriculum-based exercise program increases bone mineral accrual and bone size in prepubertal girls: two-year data from the pediatric osteoporosis prevention (POP) study.

UNLABELLED: This 2-year prospective controlled exercise intervention trial in 99 girls at Tanner stage 1, evaluating a school curriculum-based training program on a population-based level, showed that the annual gain in BMC, aBMD, and bone size was greater in the intervention group than in the controls. INTRODUCTION: Most exercise intervention studies in children, evaluating the accrual of BMD, include volunteers and use specifically designed osteogenic exercise programs. The aim of this study was to evaluate a 2-year general school-based exercise intervention program in a population-based cohort of girls at Tanner stage 1. MATERIALS AND METHODS: Forty-nine girls 7-9 years of age in grades 1 and 2 in one school were included in a school curriculum-based exercise intervention program of general physical activity for 40 minutes per school day (200 minutes/week). Fifty healthy age-matched girls in three neighboring schools, assigned to the general Swedish school curriculum of physical activity (60 minutes/week), served as controls. All girls were premenarchal, remaining in Tanner stage 1 during the study. BMC (g) and areal BMD (aBMD; g/cm2) were measured with DXA of the total body (TB), the lumbar spine (L2-L4 vertebrae), the third lumbar vertebra (L3), the femoral neck (FN), and the leg. Volumetric BMD (vBMD; g/cm3) and bone size were calculated at L3 and FN. Total lean body mass and total fat mass were estimated from the total body scan. Height and weight were also registered. Baseline measurements were performed before the intervention was initiated. Follow-up was done after 2 years. RESULTS: No differences between the groups were found at baseline in age, anthropometrics, or bone parameters. The annual gain in BMC was greater in the intervention group than in the controls: L2-L4, mean 3.8 percentage points (p = 0.007); L3 vertebra, mean 7.2 percentage points (p < 0.001); legs, mean 3.0 percentage points (p = 0.07). The intervention group had a greater annual gain in aBMD: total body, mean 0.6 percentage points (p = 0.006), L2-L4, mean 1.2 percentage points (p = 0.02), L3 vertebra, mean 1.6 percentage points (p = 0.006); legs, mean 1.2 percentage points (p = 0.007). There was also a greater mean annual gain in bone size in the L3 vertebra (mean 1.8 percentage points; p < 0.001) and in the FN (mean 0.3 percentage points; p = 0.02). CONCLUSIONS: A general school-based exercise program for 2 years for 7- to 9-year-old girls (baseline) enhances the accrual of BMC and BMD and increases bone size.

Bone and Bones↗
PubMed2005

Contribution of hip strength indices to hip fracture risk in elderly men and women.

UNLABELLED: In this prospective, case-control study, femoral neck diameter, cross-sectional moment of inertia, or section modulus was an independent predictor of hip fracture risk after adjustment for BMD. However, the contribution of each of these indices to hip fracture prediction was modest in the presence of BMD. INTRODUCTION: The relative contribution of measures of hip strength to hip fracture prediction is unclear. This study was designed to characterize the association between hip strength indices and hip fracture risk in relation to BMD in elderly men and women. MATERIALS AND METHODS: Seventy-one women and 25 men>or=60 years of age, who sustained a hip fracture during the study period of 1989-2003, were selected from the prospective, population-based Dubbo Osteoporosis Epidemiology Study. These fracture cases were randomly matched for age and sex in a 1:2 ratio with nonfracture individuals. BMD at the femoral neck was measured before the fracture event by DXA (Lunar DPX-L). Hip strength indices, including femoral neck diameter (FND), cross-sectional moment of inertia (CSMI), and section modulus (Z), were estimated by reanalysis of the image files using hip strength analysis software. RESULTS: In women, after adjustment for BMD, increased risk of hip fracture was associated with smaller FND (OR, 1.6; 95% CI, 1.0, 2.7), lower CSMI (OR, 1.8; 95% CI, 1.0, 3.2), or Z (OR, 1.6; 95% CI, 1.1, 5.1). In men, none of these hip strength indices were significant predictors of fracture risk. However, using the results in women as a prior distribution, it was estimated that the BMD-adjusted OR for FND (OR, 1.5; 95% CI, 1.0, 2.3), CSMI (OR, 1.6; 95% CI, 1.0, 2.5), or Z (OR, 2.3; 95% CI, 1.4, 3.9) was each significantly associated with hip fracture risk in men. In the logistic regression model, BMD alone accounted for 32% and 16% of the variance of fracture liability in women and men, respectively. The addition of FND, CSMI, or Z to the model increased the respective variance proportion to 34% and 19%. CONCLUSIONS: These data suggest that smaller FND and lower CSMI or Z is an independent risk factor for hip fracture in both women and men. However, the contribution of these measures to hip fracture prediction over and above BMD is likely modest.

Aged↗
PubMed2005

Maternity and bone mineral density.

During pregnancy and lactation, changes occur in a variety of factors which have great potential to influence bone mineral density (BMD). Smoking habits, the level of alcohol consumption, the level of physical activity, body weight, soft tissue composition and hormone levels are all factors that change during the course of these conditions. Some of these factors are capable of increasing BMD, and some can reduce it. Due to these various changes, it is virtually impossible to predict the development in BMD that will occur during a pregnancy and lactation. However, longitudinal studies have suggested that both pregnancy and lactation are associated with a BMD loss of up to 5%, albeit that the BMD recovers after weaning. Cross-sectional studies have indicated that women with many children and a long total period of lactation have similar or higher BMD and similar or lower fracture risk than their peers who have not given birth. As the studies showing this trend have been observational and cross sectional case-control studies, the conclusions can only be regarded as being suggestive, and no causality can be proven.

Bone Density↗
PubMed2004

An age-related medullary expansion can have implications for the long-term fixation of hip prostheses.

BACKGROUND: Diaphyseal bone loss occurs mainly at the endosteal surface in the medullary cavity. Since the menopause is followed by an increase in bone loss, the size of the medullary cavity should theoretically increase during the postmenopausal period. If so, this might affect the long-term fixation of hip prostheses. PATIENTS AND METHODS: This 19-year prospective study evaluated bone loss and geometrical changes in 112 women, all premenopausal at baseline. Bone mineral density (BMD) and skeletal geometry, with special reference to the size of the medullary cavity, were estimated every other year by single-photon absorptiometry at the cortical site of the distal radius. RESULTS: After menopause, a decrease of 1.7 (95% CI 1.6-1.8)% occurred in the BMD every year, while an increase of 0.9 (0.8-1.0)% in the medullary width (endosteal width) too place every year. The annual change in BMD was inversely correlated with the annual change in the medullary width (r = -0.5, p < 0.001). The quartile of women with the largest BMD loss had a greater medullary expansion than the quartile of women with the least BMD loss (p < 0.001). INTERPRETATION: If the age-related expansion of the radial medullary cavity is a general phenomenon, this may have implications for the long-term fixation of hip prostheses.

Absorptiometry, Photon↗
PubMed2004

Long term effects of oestrogen therapy on bone loss in postmenopausal women: a 23 year prospective study.

OBJECTIVE: To determine the long term effect of oestrogen therapy on bone loss after menopause. DESIGN: Prospective observational study over 23 years. SETTING: Malmö, Sweden. SUBJECTS: Twenty-eight women taking oestrogen and 196 women not taking oestrogen during the follow up. METHODS: Bone mineral density of the forearm was measured by single-photon absorptiometry at age 48 and 72 years. Use of oestrogen therapy was noted. MAIN OUTCOME MEASURE: Rate of forearm bone loss between the age of 48 and 72 years. RESULTS: Women taking oestrogen, for a median of 17 years (range 4 to 26), had 8.7 percentage points (95% CI 3.8-13.5) lower rate of bone loss compared with women not taking oestrogen during the same period. Each year of oestrogen therapy reduced the rate of bone loss by 0.8 percentage points (95% CI 0.2-1.4). CONCLUSIONS: The use of oestrogen seems to reduce the rate of bone loss over a period of 23 years, and the longer the duration of the therapy, the less bone loss.

Absorptiometry, Photon↗
PubMed2003

Bone loss and bone size after menopause.

BACKGROUND: Bone loss increases after menopause. However, bone strength also depends on structural characteristics such as bone size. Whether bone size increases as a result of periosteal apposition and whether a strength index accounting for both bone density and bone size might predict the risk of fracture better than bone density alone are unclear. METHODS: Bone mass and the skeletal structure of the distal radius were evaluated by single-photon absorptiometry every other year in 108 women, all of whom were followed from the time of menopause for a mean period of 15 years. Postmenopausal serum estradiol levels and fractures of the distal radius were noted. RESULTS: The mean (+/-SD) annual decrease in bone mineral density was 1.9+/-0.7 percent. The medullary bone diameter increased annually by 1.1+/-0.9 percent, and the periosteal diameter by 0.7+/-0.3 percent; the strength index decreased by 0.7+/-0.7 percent. The expansion of the medullary diameter and the expansion of the periosteal diameter were correlated with one another (r = 0.54, P<0.001), and women in the highest quartile of medullary expansion had more loss of bone mineral density and greater periosteal apposition than women in the lowest quartile (P<0.001 for both comparisons). The postmenopausal serum estradiol level was correlated with changes in the periosteal diameter (r = -0.25, P=0.009) and with changes in bone mineral density (r = 0.34, P<0.001). A 1-SD decrement in the strength index at base line was associated with a risk ratio for fracture of the distal radius of 3.8 (95 percent confidence interval, 1.8 to 8.0). CONCLUSIONS: Increased bone loss after menopause is associated with increased periosteal apposition, which partially preserves bone strength. A strength index may be a helpful predictor of the risk of fracture.

Biomechanical Phenomena↗
PubMedDate not supplied

Low regional tibial bone density in athletes with medial tibial stress syndrome normalizes after recovery from symptoms.

BACKGROUND: Although the exact cause of medial tibial stress syndrome is unclear, changes in bone metabolism are likely to be involved. HYPOTHESIS: Localized low bone mineral density at the junction of the middle and distal thirds of the tibia in patients with medial tibial stress syndrome develops in conjunction with the symptoms; these changes are reversible and are not inherited. STUDY DESIGN: Prospective cohort study. METHODS: Bone mineral density in 14 adult male athletes with long-standing medial tibial stress syndrome was measured when they were symptomatic and after recovery (mean follow-up, 5.7 years). Repeat measurements were also made prospectively in 13 nonathlete control subjects and single measurements were made in 18 healthy athletes. RESULTS: Bone mineral density was 9% +/- 11% higher in the proximal tibia but 11% +/- 12% lower in the tibial region corresponding to pain in patients when compared with nonathlete control subjects. It increased by 19% +/- 11% in the region of pain after recovery from symptoms and, at follow-up, was no lower than in nonathlete control subjects. CONCLUSION: Athletes with medial tibial stress syndrome and increased scintigraphic uptake regain normal tibial bone mineral density after recovery from symptoms. Initially localized low bone mineral density is not an inherited condition, but instead may develop in conjunction with the symptoms.

Adult↗
PubMedDate not supplied

[Pregnancy and lactation are not risk factors for osteoporosis or fractures].

Observational and case control studies infer that a pregnancy and a period of lactation are followed by loss in bone mass of up to 5%. The reason for this loss is virtually impossible to conclude as so many factors known to influence the bone mass undergo changes during a pregnancy and lactation. The increased calcium demand, changed nutritional habits, reduced smoking and alcohol consumption seen in many women during these periods, the changes in body weight and fat content, the changed level of physical activity and the changed levels of hormones with potential to influence the bone metabolism could all influence the bone mass. Most studies also report that the deficit in "bone mass" normalises after weaning. Multiple pregnancies and long total duration of lactation can not be regarded as risk factors for osteoporosis and fragility fractures as most reports indicate that women with multiple pregnancies have similar or higher bone mass and similar or lower fracture incidence than their peers with no children.

Adult↗