A cross-sectional study of smoking and bone mineral density in premenopausal parous women: effect of body mass index, breastfeeding, and sports participation

Effect of cigarette smoking on alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth: a controlled clinical trial

OBJECTIVE

To evaluate the effect of cigarette smoking on the alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth.

METHODS

This controlled clinical trial involved 17 smokers and 17 nonsmokers with mild to moderate crowding of the anterior mandibular teeth. Two cone-beam computed tomography images of the mandible were taken before and after treatment. The length of each tooth root was calculated in each T0 image, and the root was divided into three equal regions. Three lines were drawn parallel to the line of the cementoenamel junction at these three regions of the root, and the previously drawn lines were used to measure bone thickness and bone density.

RESULTS

The mean changes in cortical bone thickness and bone density were significantly smaller in smokers than nonsmokers. Cortical bone thickness and bone density were significantly lower after than before treatment in both smokers and nonsmokers.

CONCLUSION

In addition to all of its known dangers, cigarette smoking may also harm the alveolar bone by decreasing the bone thickness and density during orthodontic treatment in heavy smokers.

Modifiable lifestyle factors associated with fragility hip fracture: a systematic review and meta-analysis

INTRODUCTION

Among the various hip fracture predictors explored to date, modifiable risk factors warrant special consideration, since they present promising targets for preventative measures. This systematic review and meta-analysis aims to assess various modifiable risk factors.

MATERIAL AND METHODS

We searched four online databases in September 2017. We included studies that reported on modifiable lifestyle risk factors for sustaining fragility hip fractures. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). The inclusion criteria consisted of (1) adult patients with osteoporotic hip fracture, (2) original study, (3) availability of full text articles in English, and (4) report of a modifiable lifestyle risk factor.

RESULTS

Thirty-five studies, containing 1,508,366 subjects in total, were included in this study. The modifiable risk factors that were significantly associated with an increased risk of hip fracture were the following: weight < 58 kg (128 lbs) (pooled OR 4.01, 95% CI 1.62-9.90), underweight body mass index (BMI) (< 18.5) (pooled OR 2.83, 95% CI 1.82-4.39), consumption of ≥ 3 cups of coffee daily (pooled OR 2.27, 95% CI 1.04-4.97), inactivity (pooled OR 2.14, 95% CI 1.21-3.77), weight loss (pooled OR 1.88, 95% CI 1.32-2.68), consumption of ≥ 27 g (approx. > 2 standard drinks) alcohol per day (pooled OR 1.54, 95% CI 1.12-2.13), and being a current smoker (pooled OR 1.50, 95% CI 1.22-1.85). Conversely, two factors were significantly associated with a decreased risk of hip fracture: obese BMI (> 30) (pooled OR 0.58, 95% CI 0.34-0.99) and habitual tea drinking (pooled OR 0.72, 95% CI 0.66-0.80).

CONCLUSION

Modifiable factors may be utilized clinically to provide more effective lifestyle interventions for at risk populations. We found that low weight and underweight BMI carried the highest risk, followed by high coffee consumption, inactivity, weight loss, and high daily alcohol consumption.

Effects of smoking habit change on hospitalized fractures: a retrospective cohort study in a male population

We examined effects of smoking habit change on fracture risk in men. Long-term quitters and never smokers showed decreased risk for overall fractures, lumbar fractures, and other site fractures. Short-term quitters did not show decreased risk. Longer time since smoking cessation may lead to decreased fracture risk in men.

PURPOSE

Cigarette smoking is a well-known modifiable risk factor of osteoporosis and fractures. This study investigated the effects of change in smoking habits on risks of all types of fractures in men using a nationwide health claims database.

METHODS

Retrospective study was performed using the Korean National Health Insurance Service-National Sample Cohort Data. Cox proportional hazards regression analyses were performed to estimate risks of all types of hospitalized fractures, hip fractures, lumbar fractures, and other site fractures (all other fractures excluding the lumbar and hip areas).

RESULTS

Compared to continued smokers, long-term quitters and never smokers showed decreased risk for all types of fractures (adjusted hazard ratio (aHR) 0.83, 95% confidence interval (CI) 0.78-0.88 and aHR 0.84, 95% CI 0.80-0.89, respectively). According to skeletal site, long-term quitters and never smokers showed decreased risk for lumbar fractures (aHR 0.82, 95% CI 0.68-0.98 and aHR 0.85, 95% CI 0.73-0.99, respectively) and other site fractures (aHR 0.83, 95% CI 0.78-0.89 and aHR 0.85, 95% CI 0.81-0.90, respectively). Hip fractures were decreased in never smokers (aHR 0.77, 95% CI 0.62-0.94). Short-term quitters did not show decreased risk for fractures.

CONCLUSIONS

Longer time since smoking cessation in men may lead to decreased risk for fractures, especially lumbar and other site fractures. Physicians should counsel patients at risk for fractures both to quit smoking and to maintain abstinence from smoking. Further studies may be required to help comprehend how smoking cessation can affect fracture risk.

Vitamin D deficiency in a European inflammatory bowel disease inception cohort: an Epi-IBD study

BACKGROUND

Serum vitamin D level is commonly low in patients with inflammatory bowel disease (IBD). Although there is a growing body of evidence that links low vitamin D level to certain aspects of IBD such as disease activity and quality of life, data on its prevalence and how it varies across disease phenotype, smoking status and treatment groups are still missing.

MATERIALS AND METHODS

Patients diagnosed with IBD between 2010 and 2011 were recruited. Demographic data and serum vitamin D levels were collected. Variance of vitamin D level was then assessed across different treatment groups, disease phenotype, disease activity and quality of life scores.

RESULTS

A total of 238 (55.9% male) patients were included. Overall, 79% of the patients had either insufficient or deficient levels of vitamin D at diagnosis. Patients needing corticosteroid treatment at 1 year had significantly lower vitamin D levels at diagnosis (median 36.0 nmol/l) (P=0.035). Harvey-Bradshaw Index (P=0.0001) and Simple Clinical Colitis Activity Index scores (P=0.0001) were significantly lower in patients with higher vitamin D level. Serum vitamin D level correlated significantly with SIBQ score (P=0.0001) and with multiple components of SF12. Smokers at diagnosis had the lowest vitamin D levels (vitamin D: 34 nmol/l; P=0.053).

CONCLUSION

This study demonstrates the high prevalence of low vitamin D levels in treatment-naive European IBD populations. Furthermore, it demonstrates the presence of low vitamin D levels in patients with IBD who smoke.

Individualized Fracture Risk Feedback and Long-term Benefits After 10 Years

INTRODUCTION

This study aimed to determine if beneficial effects of individualized feedback of fracture risk on osteoporosis preventive behaviors and bone mineral density observed in a 2-year trial were sustained long-term.

METHODS

This was a 10-year follow-up of a 2-year RCT in 470 premenopausal women aged 25-44 years, who were randomized to one of two educational interventions (the Osteoporosis Prevention and Self-Management Course [OPSMC] or an osteoporosis information leaflet) and received tailored feedback of their relative risk of fracture in later life (high versus normal risk groups). Bone mineral density of lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. Physical activity, dietary calcium intake, calcium and vitamin D supplements, and smoking status were measured by questionnaires.

RESULTS

From 2 to 12 years, the high-risk group had a smaller decrease in femoral neck bone mineral density (β=0.023, 95% CI=0.005, 0.041 g/cm²) but similar lumbar spine bone mineral density change as the normal-risk group. They were more likely to use calcium (relative risk=1.66, 95% CI=1.22, 2.24) and vitamin D supplements (1.99, 95% CI=1.27, 3.11). The OPSMC had no effects on bone mineral density change. Both high-risk (versus normal-risk) and the OPSMC groups (versus leaflet) had a more favorable pattern of smoking behavior change (relative risk=1.85, 95% CI=0.70, 4.89 and relative risk=2.27, 95% CI=0.86, 6.01 for smoking cessation; relative risk=0.33, 95% CI=0.13, 0.80 and relative risk=0.28, 95% CI=0.10, 0.79 for commenced or persistent smoking).

CONCLUSIONS

Feedback of high fracture risk to younger women was associated with long-term improvements in osteoporosis preventive behaviors and attenuated femoral neck bone mineral density loss. Therefore, this could be considered as a strategy to prevent osteoporosis.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) NCT00273260.

Associations of dietary patterns with bone mass, muscle strength and balance in a cohort of Australian middle-aged women

Influences of dietary patterns on musculoskeletal health are poorly understood in middle-aged women. This cross-sectional analysis from a cohort of 347 women (aged 36-57 years) aimed to examine associations between dietary patterns and musculoskeletal health outcomes in middle-aged women. Diet was measured by the Cancer Council of Victoria FFQ. Total body bone mineral content (TB BMC), femoral neck and lumbar spine bone density (dual-energy X-ray absorptiometry), lower limbs muscle strength (LMS) and balance tests (timed up and go test, step test, functional reach test (FRT) and lateral reach test) were also measured. Exploratory factor analysis was used to identify dietary patterns and scores for each pattern generated using factor loadings with absolute values ≥0·20. Associations between food pattern scores and musculoskeletal outcomes were assessed using multivariable linear regression. Three dietary patterns were identified: 'Healthy' (high consumption of a plant-based diet - vegetables, legumes, fruit, tomatoes, nuts, snacks, garlic, whole grains and low intake of high-fat dairy products), 'high protein, high fat' (red meats, poultry, processed meats, potatoes, cruciferous and dark-yellow vegetables, fish, chips, spirits and high-fat dairy products) and 'Processed foods' (high intakes of meat pies, hamburgers, beer, sweets, fruit juice, processed meats, snacks, spirits, pizza and low intake of cruciferous vegetables). After adjustment for confounders, Healthy pattern was positively associated with LMS, whereas Processed foods pattern was inversely associated with TB BMC and FRT. The associations were not significant after accounting for multiple comparisons. There were no associations with any other outcomes. These results suggest that maintaining a healthy diet could contribute to bone acquisition, muscle strength and balance in adult life. However, while they provide some support for further investigating dietary strategies for prevention of age-related loss of muscle and deterioration in balance, the exploratory nature of the analyses means that confirmation in longitudinal studies and/or trials with pre-specified hypotheses is needed.

Effect of Cigarette Smoking on Risk of Hip Fracture in Men: A Meta-Analysis of 14 Prospective Cohort Studies

BACKGROUND

Several observational studies have suggested an association between cigarette smoking and risk of hip fracture. However, no formal systematic review or meta-analysis was performed to summarize this risk in men.

MATERIALS AND METHODS

A search was applied to MEDLINE, EMBASE, and web of science (up to November 1 2016). All prospective cohort studies assessing risk of hip fracture with the factor of cigarette smoking in men without language restriction were reviewed, and qualities of all included studies were assessed using the Newcastle-Ottawa Scale. Two authors independently assessed literatures and extracted information eligibility, and any disagreement was resolved by consensus. Newcastle-Ottawa quality assessment scale was used to evaluate studies' quality in meta-analyses. We calculated the RR with 95% CIs in a random-effects model as well as the fixed-effects model using the metan command in the STATA version 12.0 (StataCorp, USA).

RESULTS

Fourteen prospective cohort studies were eligible for the present analysis. A meta-analysis of 12 prospective studies showed that the relative risk (RR) for current male smoking was 1.47 [95% confidence interval (CI) (1.28-1.66), p = 0.54; I2 = 0%]. Subgroup analyses show study characteristics (including geography region, length of follow-up, size of cohorts and study quality) did not substantially influence these positive associations. Eight studies reported the RRs for former smokers compared with never smokers and the pooled RR was 1.15 [95% CI, (0.97-1.34), (I2 = 0%, p = 0.975)].

CONCLUSIONS

The present meta-analysis of 14 prospective studies suggests that, compared with never smokers, cigarette smoking increases risk of hip fracture in man, specifically in current smokers. However, further larger prospective cohorts with more power or meta-analysis of individual patient data are needed to confirm this association.

Effect of Multiparity and Prolonged Lactation on Bone Mineral Density

OBJECTIVES

This study was done to determine the effect of multiparity and prolonged lactation on bone mineral density (BMD).

METHODS

This cross-sectional study included 196 perimenopausal and postmenopausal women aged 40 to 60 years old. Age, body mass index (BMI), menopausal status, duration of menopause, parity and total duration of lactation, nutritional history were recorded. Lumbar spine (LS; L2-L4) and femur neck (FN) BMD were measured using dual energy X-ray absorptiometry. Correlation of parity and lactation with BMD were investigated using multiple regression analysis.

RESULTS

Parity was inversely correlated to BMD for LS (β = -0.266, P = 0.001) and FN (β = -0.380, P = 0.000). This relation remained significant even after adjusting for age, BMI and duration of menopause. Duration of lactation was inversely correlated with BMD for LS (β = -0.271, P = 0.001) but no for FN (β = -0.124, P = 0.130).

CONCLUSIONS

Multiparity and prolonged lactation have negative impact on BMD especially with in a socioeconomic group whose nutritional intake is borderline. Our data support that parity and duration of lactation can be associated with future osteoporosis.

Lower limb muscle strength is associated with poor balance in middle-aged women: linear and nonlinear analyses

This was the first study investigating both linear associations between lower limb muscle strength and balance in middle-aged women and the potential for thresholds for the associations. There was strong evidence that even in middle-aged women, poorer LMS was associated with reduced balance. However, no evidence was found for thresholds.

INTRODUCTION

Decline in balance begins in middle age, yet, the role of muscle strength in balance is rarely examined in this age group. We aimed to determine the association between lower limb muscle strength (LMS) and balance in middle-aged women and investigate whether cut-points of LMS exist that might identify women at risk of poorer balance.

METHODS

Cross-sectional analysis of 345 women aged 36-57 years was done. Associations between LMS and balance tests (timed up and go (TUG), step test (ST), functional reach test (FRT), and lateral reach test (LRT)) were assessed using linear regression. Nonlinear associations were explored using locally weighted regression smoothing (LOWESS) and potential cut-points identified using nonlinear least-squares estimation. Segmented regression was used to estimate associations above and below the identified cut-points.

RESULTS

Weaker LMS was associated with poorer performance on the TUG (β -0.008 (95 % CI: -0.010, -0.005) second/kg), ST (β 0.031 (0.011, 0.051) step/kg), FRT (β 0.071 (0.047, 0.096) cm/kg), and LRT (β 0.028 (0.011, 0.044) cm/kg), independent of confounders. Potential nonlinear associations were evident from LOWESS results; significant cut-points of LMS were identified for all balance tests (29-50 kg). However, excepting ST, cut-points did not persist after excluding potentially influential data points.

CONCLUSIONS

In middle-aged women, poorer LMS is associated with reduced balance. Therefore, improving muscle strength in middle-age may be a useful strategy to improve balance and reduce falls risk in later life. Middle-aged women with low muscle strength may be an effective target group for future randomized controlled trials.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) NCT00273260.

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Assessment of smoking for low bone mineral density in postmenopausal Turkish women

OBJECTIVE

To investigate the effect of cigarette smoking on bone mineral density (BMD) in postmenopausal Turkish women.

STUDY DESIGN

A total of 175 postmenopausal Turkish women admitted to Tepecik Training and Research Hospital for a routine menopausal checkup were included in this study. All participants completed a questionnaire regarding their age, educational status, parity, number of abortus, time since menopause, caffeine intake, tobacco use, alcohol consumption, history of a previous fracture related to trauma, and taking any medication for menopause and osteoporosis. Of all subjects, 23.3% (n = 39) were smokers and 77.7% (n = 136) were nonsmokers. T-scores and Z-scores of vertebra and femur neck were assessed using dual energy X-ray absorptiometry (DXA). For analyzing the results, Student t-test, one-way ANOVA, Mann-Whitney U test, Pearson correlation, and Kruskal-Wallis test were performed.

RESULTS

Femur T-scores (- 0.78 ± 1.07 vs. - 0.32 ± 1.56) and vertebra T-scores (- 2.26 ± 1.23 vs. - 1.82 ± 1.04) were significantly lower in smoking women than nonsmoking women (p < 0.05). However, there were no significant difference between duration of smoking, number of cigarettes consumed per day, and BMD (p > 0.05) CONCLUSION: Cigarette smoking is one of the modifiable risk factors influencing bone density in postmenopausal Turkish women. "Cessation of cigarette" should be recommended for lifestyle modifications to prevent postmenopausal osteoporosis.

Effects of individualized bone density feedback and educational interventions on osteoporosis knowledge and self-efficacy: a 12-yr prospective study

This is 12-yr follow-up of a randomized controlled trial aimed to evaluate the long-term effects of bone density feedback and osteoporosis education on osteoporosis knowledge and self-efficacy. We examined the effects of feedback of bone density-defined fracture risk (high [T-score <0] vs normal [T-score ≥0] risk) and 2 different educational interventions (the group-based Osteoporosis Prevention and Self-Management Course [OPSMC] vs an osteoporosis leaflet) on osteoporosis knowledge and self-efficacy in women aged 25-44. Seventy-four percent (N = 347) of 470 participants at baseline participated at 12 yr. Overall, the scores were higher for osteoporosis knowledge but lower for self-efficacy at 12 yr. However, neither intervention had an effect on the change in knowledge (T-score, β = 0.4, 95% confidence interval [CI] = -0.3 to 1.1; OPSMC, β = 0.2, 95% CI = -0.5 to 0.9) or self-efficacy (T-score, β = -1.1, 95% CI = -2.5 to 0.4; OPSMC, β = -0.2, 95% CI = -1.6 to 1.3). Women in households with an unemployed main financial provider had a decrease in knowledge at 12 yr compared with those in households with an employed main financial provider in whom knowledge increased (β = -1.95, 95% CI = -3.40 to -0.50), but there were no other predictors of change identified for knowledge or self-efficacy. In conclusion, beneficial effects of both OPSMC and feedback of high fracture risk on osteoporosis knowledge seen previously at 2 yr were not sustained after 12 yr although overall knowledge was still significantly higher than at baseline. Neither intervention improved osteoporosis self-efficacy. More frequent osteoporosis education and bone density feedback may be required to maintain knowledge, and other approaches to improve self-efficacy are necessary.

Lifestyle modifications to improve musculoskeletal and bone health and reduce disability--a life-course approach

This review covers the evidence relating to lifestye modification in the big three musculoskeletal conditions: osteoarthritis, osteoporosis and rheumatoid arthritis. Lifestyle is of considerable importance in the first two and there is emerging evidence for rheumatoid arthritis despite it not traditionally being considered a lifestyle disease.

The relationship between pulmonary function and bone mineral density in healthy nonsmoking women: the Korean National Health and Nutrition Examination Survey (KNHANES) 2010

The aim of this study was to examine the association between pulmonary function and bone mineral density (BMD) in subjects who had never smoked. Pulmonary function was associated with BMD in premenopausal, but not postmenopausal, women.

INTRODUCTION

It has been reported that low bone mass is common in patients with pulmonary disorders such as chronic obstructive pulmonary disease. However, in healthy nonsmoking women, the relationship between bone mass and pulmonary function has yet to be clarified. The object of this study was to determine whether pulmonary function is related to BMD in healthy nonsmoking women based on menopausal status.

METHODS

This study was a cross-sectional study based on data obtained from the Korean National Health and Nutrition Examination Survey (KNHANES), a nationwide representative survey conducted by the Korean Ministry of Health and Welfare in 2010. This study included 456 subjects who had never smoked and analyzed data concerning pulmonary function and BMD.

RESULTS

Functional vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were correlated with BMD at lumbar spine, femur neck (FN), and total hip in premenopausal women (p = 0.030, p = 0.003, p = 0.019, respectively, for FVC; p = 0.015, p = 0.006, p = 0.059, respectively, for FEV1). However, FVC and FEV1 were only correlated with BMD at FN in postmenopausal women (p = 0.003 for FVC; p = 0.006 for FEV1). Body mass index (BMI), FVC, and FEV1 were significantly related with BMD at FN, even after adjusting for age and other confounding factors (β = 0.334, p < 0.001; β = 0.145, p = 0.017; and β = 0.129, p = 0.037, respectively) in premenopausal women. However, only age and BMI were correlated with BMD at FN (β = -0.268, p = 0.001 and β = 0.384, p > 0.001) in postmenopausal women after adjusting for confounding factors.

CONCLUSIONS

Pulmonary function, including FVC and FEV1 are associated with BMD at FN in healthy nonsmoking premenopausal women but not in postmenopausal women.

Adverse effects of smoking on peak bone mass may be attenuated by higher body mass index in young female smokers

Smoking is associated with postmenopausal bone loss and fracture, but the effect of smoking on bone in younger women is unclear. Peak bone mass is an important determinant for fracture risk; therefore, our aim was to evaluate the association between smoking and bone mass in 25-year-old women, specifically the influence of daily cigarette consumption and total exposure, duration, age at starting smoking, and time since smoking cessation on bone density and fracture risk. Smoking and bone mineral density (BMD) data were available for 1,054 women from the PEAK-25 cohort. Analyses comparing current smokers with women who never smoked were performed using number of cigarettes per day, pack-years, smoking duration, age smoking started, and, for former smokers, age at quitting. BMD did not differ between never, former, and current smokers; and the relative fracture risk in smokers was not significant (relative risk [RR] = 1.2, 95 % confidence interval 0.8-1.9). Among current smokers, BMD decreased with a dose response as cigarette consumption increased (femoral neck p = 0.037). BMD was not significantly lower in young women who had smoked for long duration or started smoking early (p = 0.07-0.64); long duration and early start were associated with higher body mass index (BMI; p = 0.038). Lower BMD persisted up to 24 months after smoking cessation (p = 0.027-0.050), becoming comparable to never-smokers after 24 months. Hip BMD was negatively associated with smoking and dose-dependent on cigarette consumption. Smoking duration was not associated with BMD, although young women with a long smoking history had higher BMI, which might attenuate the adverse effects from smoking.

The effects of smoking on bone metabolism

Osteoporosis is a common, morbid and costly disorder characterized by deterioration in bone strength. Cigarette smoking is associated with reduced bone mineral density (BMD) and increased fracture risk. There are basic, clinical, and observational studies that define several of the underlying pathophysiologic mechanisms that predispose smokers to bone loss. Such mechanisms include alterations in calciotropic hormone metabolism and intestinal calcium absorption, dysregulation in sex hormone production and metabolism, alterations in adrenal cortical hormone metabolism and in the receptor activator of nuclear factor kappa-B (RANK), receptor activator of nuclear factor kappa-B ligand (RANKL), and osteoprotegerin (OPG) system (RANK-RANKL-OPG system), and direct cellular effects of cigarette use on bone cells. In addition, there is evidence of reversibility in the aforementioned mechanisms with smoking cessation. In summary, cigarette smoking is a reversible risk factor for osteoporosis and osteoporotic fractures through diverse pathophysiologic mechanisms.

The effect of breast-feeding duration on bone mineral density in postmenopausal Turkish women: a population-based study

INTRODUCTION

In the present study, we investigated the effects of breast-feeding time on bone mineral density (BMD) later in life.

MATERIAL AND METHODS

The current study was based on a retrospective analysis of 586 postmenopausal women with a mean age of 60.8 years, who were screened for osteoporosis by dual energy X-ray absorptiometry (DXA).They were classified into 4 groups with respect to the duration of their breast-feeding as never (group 1), 1-24 months (group 2), 25-60 months (group 3), or > 60 months (group 4). Bone mineral density results for the femur neck and lumbar spine were classified into 3 groups according to WHO criteria as normal (T score > -1.0 SD), osteopenia (T score -1.0 to -2.5 SD), and osteoporosis (T score < -2.5 SD). Patients with osteopenia or osteoporosis (T score < -1.0 SD) were considered as having low bone mass (LBM).

RESULTS

We found a correlation between duration of lactation and femur BMD or spine BMD in the study population (r = 0.116, p < 0.005; r = -0.151, p = 0.001, respectively). Significant differences were found between femur BMD and spine BMD of groups in one-way ANOVA analysis (p = 0.025, p = 0.005, respectively). Additionally, when compared with the other three groups, group 4 was older and had longer duration of menopause (p < 0.01). In logistic regression analysis, age and body mass index were found as independent risk factors of LBM [odds ratio: 1.084 (95% CI 1.031-1.141); odds ratio: 0.896 (95% CI 0.859-0.935)], while duration of lactation was not found as an independent predictor of LBM.

CONCLUSIONS

In this study, we have found that changes of bone metabolism during lactation had no effect on postmenopausal BMD measured by DXA. Consequently, it can be suggested that long breast-feeding duration is not a risk factor for low bone mass later in life.

Bone density testing: an under-utilised and under-researched health education tool for osteoporosis prevention?

Feedback of fracture risk based on bone mineral density (BMD) is an under-explored potential osteoporosis education intervention. We performed a randomised controlled trial of either an osteoporosis information leaflet or small group education (the Osteoporosis Prevention and Self-Management Course (OPSMC)), combined with individualised fracture risk feedback in premenopausal women over two years. Women with a mean T-score at spine and hip of <0 were informed they were at higher risk of fracture in later life and those with T-score ≥ 0 were informed they were not. Women receiving feedback of high fracture risk had a greater increase in femoral neck, but not lumbar spine, BMD compared to the low risk group (1.6% p.a. vs. 0.7% p.a., p = 0.0001). Participation in the OPSMC had no greater effect on BMD than receiving the leaflet. Femoral neck BMD change was associated with starting calcium supplements (1.3% p.a., 95% CI +0.49, +2.17) and self-reported physical activity change (0.7% p.a., 95% CI +0.22, +1.22). Mother's report of increasing their children's calcium intake was associated with receiving the OPSMC (OR 2.3, 95% CI 1.4, 3.8) and feedback of high fracture risk (OR 2.0, 95% CI 1.2, 3.3). Fracture risk feedback based on BMD could potentially make an important contribution to osteoporosis prevention but confirmation of long-term benefits and cost effectiveness is needed before implementation can be recommended.

Risk factors associated with self-reported training-related injury before arrival at the US army ordnance school

OBJECTIVE

This study examined risk factors for self-reported injury incurred before arrival at Ordnance School for advanced individual training (AIT).

STUDY DESIGN

During AIT in-processing, soldiers (n=27,289 men and 3856 women) completed a questionnaire that collected demographic and lifestyle information, and asked if the soldier currently had an injury that would affect their AIT performance.

METHODS

Potential risk factors for self-reported injury were explored using logistic regression.

RESULTS

For men, self-reported injury was associated with older age [odds ratio (OR) >or=30 years/17-19 years=1.9], race (OR Black/Caucasian=1.2), basic combat training (BCT) site (OR Fort Benning/Fort Jackson=1.7; OR Fort Leonard Wood/Fort Jackson=1.6, OR Fort Knox/Fort Jackson=1.3), smoking on 20 or more days in the 30 days prior to BCT (OR smoker/non-smoker=1.2) and current illness (OR ill/not ill=6.2). For women, increased self-reported injury was associated with older age (OR>or=30 years/17-19 years=2.0), BCT site (OR Fort Leonard Wood/Fort Jackson=1.5) and current illness (OR ill/not ill=5.8).

CONCLUSIONS

Certain demographic characteristics and lifestyle behaviours may be identified as injury risk factors on arrival at Ordnance AIT.

Smoking among premenopausal women is associated with increased risk of low bone status: the JPOS Study

The impact of smoking on peak bone density has not been conclusively established. We examined how smoking exposure influences bone mineral density (BMD) or the risk of low bone status in premenopausal women. We conducted a baseline survey with a representative sample of Japanese women in 1996. The effect of current and former smokers (ever-smoker) was investigated with 789 premenopausal women aged 20-40 years. The multiple regression with stepwise method was used to identify significant determinants for BMD or the risk of low bone status (T-score < -1) with age, height, weight, calcium intake, coffee consumption, exercise habits, level of daily activity, parity >or= 1, and smoking as explanatory variables. The smoking effect was determined after adjusting for age, height, weight, and significant variables in the multiple regression with stepwise method. Ever-smoker was significantly associated with decreased lumbar BMD adjusted for age, height, and weight. The odds ratio of an ever-smoker for low bone status at the lumbar spine was 2.03 (95% CI 1.12, 5.82) adjusted for age, height, weight, and parity. The odds ratio for low bone status at the lumbar spine was 1.59 (95% CI 0.65, 3.91) and 2.55 (95% CI 1.12, 5.82) in those with less than 3 pack-years of tobacco use and in those with 3 or more pack-years of tobacco use, respectively. These values were adjusted for age, height, weight, and parity using a never-smoker as a reference. Cumulative smoking exposure may be associated with increased risk of low bone status among premenopausal women.

The effects of smoking on bone health

Osteoporotic fractures are a major public health problem in most developed countries and an increasing concern in much of the developing world. This healthcare burden will increase significantly worldwide over the next 20 years due to aging of the population. Smoking is a key lifestyle risk factor for bone loss and fractures that appears to be independent of other risk factors for fracture such as age, weight, sex and menopausal status. This review discusses the effects of smoking on bone health in pre-menopausal and post-menopausal women and men. Data from twin studies and the three main published meta-analyses are presented. Possible mechanisms by which smoking affects bone mass are reviewed. Despite smoking being a major lifestyle risk factor for osteoporosis, the mechanisms underlying smoking-associated bone loss and fracture risk remain poorly understood. The effect appears dose-dependent, and may be, at least partially, reversible. However, more work is required to confirm and characterize the reversibility of smoking-associated bone defects. Finally, strategies for quitting smoking are discussed. Encouragement of lifestyle alterations, including smoking cessation, should be a major component of any bone therapeutic programme.

The effect on behavior and bone mineral density of individualized bone mineral density feedback and educational interventions in premenopausal women: a randomized controlled trial [NCT00273260]

BACKGROUND

Limited information is available on ways to influence osteoporosis risk in premenopausal women. This study tested four hypotheses regarding the effects of individualized bone density (BMD) feedback and different educational interventions on osteoporosis preventive behavior and BMD in pre-menopausal women, namely: that women are more likely to change calcium intake and physical activity if their BMD is low; that group education will be more efficacious at changing behavior than an information leaflet; that BMD feedback and group education have independent effects on behavior and BMD; and, that women who improve their physical activity or calcium intake will have a change in bone mass over 2 years that is better than those who do not alter their behavior.

METHODS

We performed a 2-year randomized controlled trial of BMD feedback according to T-score and either an osteoporosis information leaflet or small group education in a population-based random sample of 470 healthy women aged 25-44 years (response rate 64%). Main outcome measures were dietary calcium intake, calcium supplement use, smoking behavior, physical activity, endurance fitness, lower limb strength and BMD. We used paired t-tests, one-way ANOVA and linear regression techniques for data analysis.

RESULTS

Women who had feedback of low BMD had a greater increase in femoral neck BMD than those with normal BMD (1.6% p.a. vs. 0.7% p.a., p = 0.0001), but there was no difference in lumbar spine BMD change between these groups (0.1% p.a. vs. 0.08% p.a., p = 0.9). Both educational interventions had similar increases in femoral neck BMD (Leaflet = +1.0% p.a., Osteoporosis self-management course = + 1.3% p.a., p = 0.4). Femoral neck BMD change was only significantly associated with starting calcium supplements (1.3 % p.a, 95%CI +0.49, +2.17) and persistent self-reported change in physical activity levels (0.7% p.a., 95%CI +0.22, +1.22).

CONCLUSION

Individualized BMD feedback combined with a minimal educational intervention is effective at increasing hip but not spine bone density in premenopausal women. The changes in behavior through which this was mediated are potentially important in the prevention of other diseases, thus measuring BMD at a young age may have substantial public health benefits, particularly if these changes are sustained.

Sociodemographic factors associated with calcium intake in premenopausal women: a cross-sectional study

OBJECTIVE

To describe associations between sociodemographic factors and calcium intake in premenopausal women.

DESIGN

Cross-sectional study.

SETTING

Population-based.

SUBJECTS

A total of 467 randomly selected, predominantly Caucasian Tasmanian women aged 25-44 y, response rate 63%.

MAIN OUTCOME MEASURES

calcium intake, sociodemographic factors, anthropometrics, osteoporosis knowledge and self-efficacy.

RESULTS

Education level, calcium-specific osteoporosis knowledge and self-efficacy were all independently associated with calcium intake (P<0.05). The odds of achieving the recommended dietary intake for calcium increased with higher levels of calcium-specific self-efficacy and knowledge, and decreased in smokers or if the household's main financial provider was unemployed (P<0.05).

CONCLUSIONS

Women who have lower levels of education, who are in households where the main financial provider is unemployed, who are smokers, and those with low levels of calcium-specific self-efficacy and knowledge are at risk of not achieving adequate calcium intake. This information will assist targeting of public health strategies aimed at improving the calcium intake of premenopausal women.

Bone mineral density, body mass index and cigarette smoking among Iranian women: implications for prevention

BACKGROUND

While risk factors of osteoporosis in Western populations have been extensively documented, such a profile has not been well studied in Caucasians of non-European origin. This study was designed to estimate the modifiable distribution and determinants of bone mineral density (BMD) among Iranian women in Australia.

METHODS

Ninety women aged 35 years and older completed a questionnaire on socio-demographic and lifestyle factors. BMD was measured at the lumbar spine (LS) and femoral neck (FN) using DXA (GE Lunar, WI, USA), and was expressed in g/cm2 as well as T-score.

RESULTS

In multiple regression analysis, advancing age, lower body mass index (BMI), and smoking were independently associated with LS and FN BMD, with the 3 factors collectively accounting for 30% and 38% variance of LS and FN BMD, respectively. LS and FN BMD in smokers was 8% lower than that in non-smokers. Further analysis of interaction between BMI and smoking revealed that the effect of smoking was only observed in the obese group (p = 0.029 for LSBMD and p = 0.007 for FNBMD), but not in the overweight and normal groups. Using T-scores from two bone sites the prevalence of osteoporosis (T-scores

CONCLUSION

These data, for the first time, indicate that apart from advancing age and lower body mass index, cigarette smoking is an important modifiable determinant of bone mineral density in these Caucasians of non-European origin.

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MESH Headings

• Absorptiometry, Photon
• Adult
• Aged
• Aging
• Australia/epidemiology
• Body Mass Index
• Bone Density
• Bone Diseases, Metabolic/diagnostic imaging
• Bone Diseases, Metabolic/epidemiology
• Cross-Sectional Studies
• Female
• Femur Neck/diagnostic imaging
• Femur Neck/metabolism
• Humans
• Iran/ethnology
• Linear Models
• Lumbar Vertebrae/diagnostic imaging
• Lumbar Vertebrae/metabolism
• Middle Aged
• Osteoporosis, Postmenopausal/diagnostic imaging
• Osteoporosis, Postmenopausal/epidemiology
• Osteoporosis, Postmenopausal/prevention & control
• Smoking

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Affiliation(s)

Azam Baheiraei Bone and Mineral Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, University of New South Wales, Sydney, Australia
Nicholas A Pocock Department of Nuclear Medicine, St Vincent's Hospital, Sydney, Australia
John A Eisman Bone and Mineral Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, University of New South Wales, Sydney, Australia
Nguyen D Nguyen Bone and Mineral Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, University of New South Wales, Sydney, Australia
Tuan V Nguyen Bone and Mineral Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, University of New South Wales, Sydney, Australia

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Effects of bone density feedback and group education on osteoporosis knowledge and osteoporosis self-efficacy in premenopausal women: a randomized controlled trial

In this 2-yr randomized controlled trial, we examined the effect of bone mineral density feedback and two different educational interventions (an osteoporosis information leaflet and group-based behavioral education [OPSMC]) on osteoporosis knowledge and self-efficacy in 470 women aged 25-44 yr. Osteoporosis knowledge increased across all intervention groups. Women receiving the OPSMC had a greater increase in both short (beta = +1.33, 95% confidence interval [CI] = 0.72-1.94) and long-term (beta = +0.64, 95% CI = 0.0034-1.25) osteoporosis knowledge, compared to those receiving the leaflet. In contrast, a low T-score was associated with a significant increase in long-term (beta = +0.66, 95% CI = 0.0034-1.25) but not short-term (beta = +0.57, 95% CI = -0.036 to 1.17) osteoporosis knowledge, compared to a normal T-score. Changes in osteoporosis self-efficacy were not associated with either low bone mineral density or receiving the OPSMC but were negatively associated with number of children (beta = -0.9, 95% CI = - 1.4 to -0.3) and working more than 20 h per week (beta = -2.7, 95% CI = -4.6 to -0.8). In conclusion, both the OPSMC and bone density feedback increased osteoporosis knowledge but not self-efficacy over 2 yr. Women with children or who worked full time have decreased osteoporosis self-efficacy, suggesting that this group should be a specific target for future interventional strategies.

Soft drink and milk consumption, physical activity, bone mass, and upper limb fractures in children: a population-based case-control study

Carbonated beverages have been reported to increase fracture risk in children but the mechanism is unclear. The aim of this population-based case-control study was to investigate the association between soft drink and milk consumption, physical activity, bone mass, and upper limb fractures in children aged 9-16 years. A total of 206 fracture cases and 206 randomly selected individually matched controls were studied. There were 47 hand fractures; 128 wrist and forearm fractures, and 31 upper arm fractures. An interviewer-administered questionnaire was utilized to retrospectively assess last-year physical activity (including television, computer, and video watching) and to recall the average weekly consumption of milk, colas, and total carbonated drinks. Bone mass at the spine, hip, and total body was assessed by dual-energy X-ray absorptiometry (DXA) and metacarpal morphometry. For total fractures, none of the above drink types was significantly different between cases and controls. For wrist and forearm fractures, there was a positive association between cola drink consumption and fracture risk (OR 1.39/unit, 95% CI: 1.01, 1.91). Cola consumption was significantly correlated with television, computer, and video watching (r = 0.20, P = 0.001) but not bone mineral density or milk drinks. After adjustment for television, computer, and video watching and bone mineral density, the association between cola drinks and fracture risk became nonsignificant (OR 1.31/unit, 95% CI: 0.94, 1.83). No association with other fracture sites was observed. In conclusion, cola, but not total carbonated beverage consumption, is associated with increased wrist and forearm fracture risk in children. However, this association is not independent of other factors and appears to be mediated by television watching and bone mineral density but not by decreased milk intake.

Television, computer, and video viewing; physical activity; and upper limb fracture risk in children: a population-based case control study

The effect of physical activity on upper limb fractures was examined in this population-based case control study with 321 age- and gender-matched pairs. Sports participation increased fracture risk in boys and decreased risk in girls. Television viewing had a deleterious dose response association with wrist and forearm fractures while light physical activity was protective.

INTRODUCTION

The aim of this population-based case control study was to examine the association between television, computer, and video viewing; types and levels of physical activity; and upper limb fractures in children 9-16 years of age.

MATERIALS AND METHODS

A total of 321 fracture cases and 321 randomly selected individually matched controls were studied. Television, computer, and video viewing and types and levels of physical activity were determined by interview-administered questionnaire. Bone strength was assessed by DXA and metacarpal morphometry.

RESULTS

In general, sports participation increased total upper limb fracture risk in boys and decreased risk in girls. Gender-specific risk estimates were significantly different for total, contact, noncontact, and high-risk sports participation as well as four individual sports (soccer, cricket, surfing, and swimming). In multivariate analysis, time spent television, computer, and video viewing in both sexes was positively associated with wrist and forearm fracture risk (OR 1.6/category, 95% CI: 1.1-2.2), whereas days involved in light physical activity participation decreased fracture risk (OR 0.8/category, 95% CI: 0.7-1.0). Sports participation increased hand (OR 1.5/sport, 95% CI: 1.1-2.0) and upper arm (OR 29.8/sport, 95% CI: 1.7-535) fracture risk in boys only and decreased wrist and forearm fracture risk in girls only (OR 0.5/sport, 95% CI: 0.3-0.9). Adjustment for bone density and metacarpal morphometry did not alter these associations.

CONCLUSION

There is gender discordance with regard to sports participation and fracture risk in children, which may reflect different approaches to sport. Importantly, television, computer, and video viewing has a dose-dependent association with wrist and forearm fractures, whereas light physical activity is protective. The mechanism is unclear but may involve bone-independent factors, or less likely, changes in bone quality not detected by DXA or metacarpal morphometry.

Lower bone mass detected at femoral neck and lumbar spine in lower-weight vs normal-weight small-boned women

Sixty-one nonsmoking, healthy, young, menstruating women aged 18 to 30 years generally considered at peak skeletal bone mass were screened for diseases and drugs known to adversely affect bone mineral density (BMD). Anthropometric measures, BMD of the lumbar spine (LS) and femoral neck (FN), exercise time, selected nutrient, and energy intake were compared. The women were categorized by frame size and body mass index (BMI), with the upper range for normal weight (NW) being BMI 23.0 to 25.9 (n=30) and lower weight (LW) being BMI 16.0-19.9 (n=31). Multivariate t tests, Pearson correlations, and independent sample t tests were used for statistical analysis. Ten of 21 in the LW group, all with small frames, had varying degrees of low BMD of the LS and/or FN. The amount of exercise time was greater in the NW group. Energy and nutrient intakes did not differ significantly between groups.

Pregnancy and lactation have no long-term deleterious effect on measures of bone mineral in healthy women: a twin study

BACKGROUND

The long-term effects of pregnancy and lactation on measures of bone mineral in women remain unclear.

OBJECTIVE

We studied whether pregnancy or lactation has deleterious long-term effects on bone mineral in healthy women.

DESIGN

We measured bone mineral density (BMD; g/cm(2)) in women aged > or = 18 y. Analyses were performed on 3 data sets: study 1, 83 female twin pairs (21 monozygous and 62 dizygous) aged (x +/- SD) 42.2 +/- 15.5 y who were discordant for ever having been pregnant beyond 20 wk; study 2, 498 twin pairs aged 42.3 +/- 15.0 y; and study 3, 1354 individual twins, their siblings, and family members.

RESULTS

In study 1, there were no significant within-pair differences in unadjusted BMD or BMD adjusted for age, height, and fat mass at the lumbar spine or total-hip or in total-body bone mineral content (BMC; kg) (paired t tests). In study 2, there was no significant within-pair difference in measures of bone mineral or body composition related to the within-pair difference in number of pregnancies. In study 3, subjects with 1 or 2 (n = 455) and > or = 3 pregnancies (n = 473) had higher adjusted lumbar spine BMD (2.9% and 3.8%, respectively; P = 0.001) and total-body BMC (2.2% and 3.1%; P < 0.001) than did nulliparous women (n = 426). Parous women who breast-fed had higher adjusted total-body BMC (2.6%; P = 0.005), total-hip BMD (3.2%; P = 0.04), and lower fat mass (10.9%; P = 0.01) than did parous non-breast-feeders.

CONCLUSION

We found no long-term detrimental effect of pregnancy or breast-feeding on bone mineral measures.

Low peak bone mineral density in healthy Lebanese subjects

Osteoporosis is a major public health problem in Western countries and is projected to have a similar impact in the Middle East. It has been suggested that peak bone mineral density (BMD), a major determinant of osteoporotic fractures later in life, may be lower in this part of the world compared with the Western world. However, subjects have not been randomly selected or systematically screened to rule out secondary causes of bone loss. The purpose of this study was to determine peak bone mass and lifestyle risk factors for bone loss in a randomly chosen sample of healthy Lebanese subjects from the greater Beirut area. Subjects 25-35 years of age were randomly selected from greater Beirut, which comprises one third of the Lebanese at large, and studied during the Fall of 1999. BMD was measured at the lumbar spine, hip, forearm, and total body. A questionnaire on lifestyle factors was administered to all subjects. Results were compared with the database of subjects from the USA provided by the manufacturer, and to the NHANES database for the total hip. Two hundred thirteen subjects were studied; 45 subjects rotated at all three centers for cross-calibration purposes. Peak BMD in Lebanese subjects was 0.2-0.9 SD below that of peak BMD in American subjects, depending on skeletal site, gender, and densitometer. These differences persisted after attempting to adjust for body size. Osteoporosis and osteopenia were more prevalent than in healthy young Americans. Height, weight, and total body fat were the most significant correlates of BMD/bone mineral content (BMC), accounting for 0.3-0.7 of the variance in bone mass measurement. Lifestyle factors had a very modest but significant contribution to bone mass variance. This is the first population-based study from the Middle East demonstrating that peak BMD is slightly lower in Lebanese subjects compared as with an established database from the USA. Due to the selection of relatively healthier subjects in our study than in the NHANES study, the actual differences between the two populations may be even greater. The impact of our findings on the epidemiology of osteoporotic fractures in Lebanon remains to be determined.

Cross-sectional study of the effects of parturition and lactation on bone mineral density later in life

OBJECTIVE

The present cross-sectional study investigated the effects of parturition and lactation on bone mineral density (BMD) later in life.

METHODS

The subjects were 456 premenopausal and 713 postmenopausal Japanese women aged 40-69 years old. They were classified into six subgroups at 5-year increments. Age, height, weight, menopausal status, age at menopause (in postmenopausal women), years since menopause (in postmenopausal women), parity, and total lactation period were recorded. Lumbar spine BMD (L2-4) was measured by dual-energy X-ray absorptiometry (DEXA). In each subgroup, correlations of parturition and lactation with BMD were investigated using Pearson's correlation test and multiple regression analyses.

RESULTS

In premenopausal women aged 40-44 years old (n=143), total lactation period was inversely correlated with BMD (r= -0.293, P<0.01). This relationship remained significant after adjusting for age, height, weight, and parity (P<0.05). Although the total lactation period was inversely correlated with BMD in the group aged 60-64 years old (r= -0.194, P<0.05, n=218), this relationship disappeared after adjusting for age, YSM, height, weight, and parity. However, in the other subgroups, there were no significant correlations between total lactation period and BMD. There were no significant correlations observed between parity and BMD in any groups.

CONCLUSION

Reproductive history of lactation and parity does not seem to be a major determinant of BMD later in life.

Breastfeeding: benefits, risks and alternatives

Obstetricians play a major role in guiding the infant feeding choices of their pregnant patients. The world literature continues to swell with reports and studies of the short- and long-term benefits to both mother and infant of breastfeeding. These benefits include protection against acute illnesses, long-term health protection, the psychological relationship and even savings in health care costs.

Sex and site differences in cartilage development: a possible explanation for variations in knee osteoarthritis in later life

OBJECTIVE

To test the hypothesis that sex-related and joint compartment-related differences in the risk of osteoarthritis (OA) of the knee might be associated with variations in cartilage development, we investigated knee cartilage volume in healthy children.

METHODS

We studied 92 children who were randomly selected from among students in grades 3-12 of a single school in Hobart, Tasmania (49 boys, 43 girls; age range 9-18 years). Articular cartilage thickness and volume were determined at the patella, medial tibial compartment, and lateral tibial compartment by magnetic resonance imaging (MRI). Sagittal T1-weighted fat-suppressed MRI images were obtained and processed on an independent computer work station.

RESULTS

Males had significantly more knee cartilage than females. Sex accounted for 6-36% of the variation in cartilage thickness and volume, which was statistically significant at all sites. Even after adjustment for age, body mass index, bone area, and physical activity, males had 16-31% higher cartilage volume; this was most marked at the medial tibial site. In addition, lateral tibial thickness was greater than medial tibial thickness (5.9 versus 3.6 mm; P < 0.0001) and lateral tibial volume was greater than medial tibial volume (2,823 versus 2,299 microl; P < 0.0001). Furthermore, physical activity was a significant explanatory factor for cartilage volume at all sites (R2 7-14% depending on site; all P < 0.05). The most consistent activity association was with vigorous activity in the previous 2 weeks (difference between any vigorous activity versus none 22-25% greater; all P < 0.05).

CONCLUSION

Sex- and joint compartment-related differences in cartilage development may be one explanation for variations in the pattern of knee OA seen in later life. Furthermore, the physical activity associations suggest that cartilage development is amenable to modification.