[Show abstract][Hide abstract] ABSTRACT: This study of 415 adolescent children examined the association between four different measures of bone mass and prevalent fracture (N = 160 children). DXA measures and calcaneal ultrasound (but not radial ultrasound or metacarpal index) were associated with upper limb fracture, suggesting heel ultrasound is also a discriminator of fractures in children.
The aim of the study was to describe the association between different measures of bone mass and prevalent fracture in adolescents.
A total of 415 adolescents (150 girls and 265 boys), mean age 16.3 years were examined. Dual energy X-ray absorptiometry (DXA) measures were performed at hip, spine, radius and total body. Calcaneal bone ultrasound attenuation (BUA), speed of sound (SOS), and stiffness were assessed by a Sahara densitometer. Radial ultrasound SOS was assessed by a Sunlight 8000P machine. Metacarpal index was calculated from a left hand X-ray. Prevalent fractures were assessed by questionnaire.
A total of 160 adolescents (39%) reported at least one previous fracture (106 upper limb, 53 lower limb, one other for first fracture). Significantly lower DXA measures, heel BUA, and heel stiffness was observed in those with a history of upper limb fracture (all P < 0.05). Despite significant correlations between all the bone mass measures, radial ultrasound and metacarpal index did not discriminate those with fracture from those without. Similar associations were present for number of fractures. No bone measure was able to discriminate lower limb fracture.
Both calcaneal quantitative ultrasound and DXA are able to discriminate adolescents with a history of upper limb fracture from those without.
Osteoporosis International 03/2008; 19(2):251-5. · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cartilage defects are highly prevalent in subjects with knee osteoarthritis (OA). Although they are associated with increased cartilage loss and joint replacement, there is little data on the natural history of cartilage defects. The aim of this study was to examine the progression of cartilage defects over 2 years in people with knee OA and to identify factors associated with progression.
One hundred and seventeen subjects with OA underwent magnetic resonance imaging of their dominant knee at baseline and follow-up. Cartilage defects were scored (0-4) at four sites. Bone size of the medial and lateral tibial plateau was determined. Height, weight, body mass index and physical activity were measured by standard protocols.
The mean cartilage defect score increased significantly over the 2-year study period in all tibiofemoral compartments (all P<0.001), except the lateral tibial compartment with age and tibial plateau bone area at baseline being predictors of progression. However, there was heterogeneity with 81% progressing at any site, 15% remaining stable and 4% decreasing.
Over 2 years, cartilage defects tend to progress in people with symptomatic OA, with only a small percentage decreasing in severity. Increasing age and increased bone area are risk factors for progression. Interventions aimed at preventing cartilage defects from occurring and reducing their severity may result in a reduction in the severity of OA, by reducing loss of articular cartilage and subsequent requirement for knee joint replacement.
Osteoarthritis and Cartilage 03/2008; 16(3):337-42. · 4.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To describe the associations between leptin, body composition, sex and knee cartilage volume/defects in older adults.
A cross-sectional sample of 190 randomly selected subjects (mean 63 years, range 52-78, 48% female) were studied. Knee cartilage volume and defects were determined using T1-weighted fat saturation MRI. Serum leptin levels were measured by radioimmunoassay. Fat and lean mass were measured by dual energy x ray absorptiometry (DXA). Body mass index (BMI) was calculated.
In multivariable analysis, serum levels of leptin were negatively associated with total cartilage volume (beta: -541 mm3/log transformed unit, 95% CI -861 to -221) but not with prevalent knee cartilage defects. BMI was negatively associated with cartilage volume after adjustment for total lean mass and positively with prevalent knee cartilage defects. However, the association between BMI and cartilage volume disappeared after adjustment for leptin while the association between BMI and cartilage defects remained unchanged. Lastly, sex differences in total cartilage volume decreased substantially after adjustment for leptin (R2 from 51% to 30%).
This cross-sectional study suggests cartilage volume loss with obesity and female sex is related to leptin and, thus, is hormonally mediated in older adults. By contrast, obesity related knee focal cartilage defects may be more related to non-hormonal factors.
Annals of the rheumatic diseases 02/2008; 67(9):1256-61. · 8.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Osteoporosis is a highly heritable disease, with estimates of genetic contribution to variance of BMD up to 80%. Genetic studies aiming to identify loci influencing BMD variation have had little success to date, largely due to inadequate power to detect the genes of small to moderate effect size likely to be involved. Adequately powered genome-wide association studies [GWAS] have successfully identified disease-associated genes in complex polygenic disorders. We performed a GWAS to search for BMD loci.
[Show abstract][Hide abstract] ABSTRACT: We studied the association between osteoporotic fractures and prior non-melanoma skin cancer (NMSC, a biomarker for cumulative sun exposure). The risk of prior NMSC in our fracture cohort was significantly reduced (standardised incidence ratio 0.69, 95% CI 0.61, 0.78). Adequate lifetime sun exposure may be necessary to protect against osteoporotic fractures in later life.
The relationship between cumulative sun exposure and osteoporotic fractures is uncertain. We aimed to study the association between non-melanoma skin cancer (NMSC), a marker of cumulative sun exposure, and osteoporotic fractures in an older cohort.
A retrospective cohort study in southern Tasmania in people aged at least 50 years with incident radiographic fracture (n = 2,283) was carried out. By record linkage to the Tasmanian Cancer Registry the cohort was followed backwards through time until the occurrence of NMSC or end-of follow-up. Relative risk was estimated by the standardised incidence ratio (SIR) using sex-, age- and calendar year-specific cancer incidence rates in southern Tasmania as reference.
The incidence of prior NMSC in the fracture cohort was 31% lower than for the general population (SIR 0.69, 95% CI 0.61, 0.78). This effect was significant for most fracture subtypes except pelvic and wrist fractures and observed for both NMSC subtypes, squamous cell carcinoma and basal cell carcinoma.
Older people with osteoporotic fractures may have had lifestyles linked to lower cumulative sunlight exposure. Achieving a balance between adequate lifetime sun exposure and protection against its adverse effects (such as fractures and skin cancer) may require assessment of individual risks.
Osteoporosis International 06/2007; 18(5):687-92. · 4.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Unlike knee plain radiography which can only detect joint space narrowing and osteophytes, magnetic resonance imaging can directly visualize and analyse the whole knee structure, including bone size, cartilage defects and loss of cartilage volume. Tibial subchondral bone area expansion may be primary and is associated with risk factors such as age, body mass index (BMI), genetics and/or limb malalignment. It can lead to the development of knee defects, which may also be caused by demographic, anthropometric and environmental factors such as age, female sex, BMI and smoking as well as structural changes such as osteophytes, bone marrow lesions, meniscal tears, meniscal extrusion and ligament abnormalities. Once knee cartilage defects develop, they have a variable natural history but are associated with subsequent cartilage loss in a dose-response manner. Both tibial subchondral bone area and knee cartilage defects are quantitatively related to the severity of knee osteoarthritis (OA), and predictive of the need for knee joint replacement in subjects with knee OA independent of radiographic change. Taken as a whole, these studies suggest that tibial subchondral bone expansion and cartilage defect development represent important targets for the prevention of cartilage loss and joint replacement.
Osteoarthritis and Cartilage 06/2007; 15(5):479-86. · 4.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Synovial haemangioma is a rare but important cause of knee symptoms, which, when undiagnosed, can lead to significant morbidity. Diagnosis is frequently difficult and delayed. We report on a case of synovial haemangioma, which demonstrates the difficulties inherent in diagnosis and the morbidity associated with diagnostic delay, in a young woman. Magnetic resonance imaging (MRI) is a useful tool for diagnosis, but detection on MRI can also be problematic, as shown by this case, demonstrating the need for greater awareness of this condition by both clinicians and radiologists. Arthroscopy is important in both the diagnosis and treatment of these lesions.
[Show abstract][Hide abstract] ABSTRACT: To describe the association between knee and hip radiographic osteoarthritis (ROA), a measure of knee pain, stiffness and functional ability and objectively measured physiological falls risk predictors.
Cross-sectional, population-based study of 850 randomly selected men and women aged 50-80 years (mean 62.5, SD 7.4). Falls risk (Z score) was determined objectively with the short form Physiological Profile Assessment (PPA). Two observers assessed knee and hip ROA using the Altman atlas. Pain, stiffness and functional ability were assessed using the Western Ontario McMasters Osteoarthritis index (WOMAC).
Overall, the study population was at a mild risk of falling. In multivariable analysis, the WOMAC function and pain score were significantly associated with reaction time, balance, proprioception, knee extension strength, and edge contrast sensitivity. Stiffness was associated with knee extension strength and edge contrast sensitivity. Males had a dose response association between the global WOMAC score and falls risk (r=0.17, P<0.001). Those who reported a global WOMAC score of 50 and above had a higher risk of falling compared to those with a score below 50 (Z score: 0.53 vs 0.14, P<0.001). Hip joint space narrowing (JSN) was significantly associated with knee extension strength (r=-0.10, P=0.003), however, no other significant associations were observed between ROA and falls risk predictors.
Self-reported functional ability and pain, and to a lesser extent, stiffness (but not knee and hip ROA), have a modest but independent association with physiological predictors of falls risk.
Osteoarthritis and Cartilage 06/2006; 14(6):533-9. · 4.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To assess whether a lifestyle intervention delivered to mothers might impact on osteoporosis preventive behaviors in their children.
We performed a 2-year randomized controlled trial of individualized bone mineral density feedback with either an osteoporosis information leaflet, or small group education, in a population-based sample of 354 mothers from Southern Tasmania, Australia in 2000-02. Main outcomes were maternal report of calcium intake and physical activity change in their children.
Receiving small group education was associated with mothers' report of increasing children's calcium intake (odds ratio 2.3, 95% confidence interval 1.4, 3.8), as was low t-score feedback (odds ratio 2.0, 95% confidence interval 1.2, 3.3). Mothers who increased their own physical activity were more often reported increasing both physical activity (odds ratio 2.7, 95% confidence interval 1.5, 5.0) and calcium intake in their children (odds ratio 2.2, 95% confidence interval 1.3, 3.7). Mothers who commenced calcium supplements more often reported increasing children's calcium intake (odds ratio 2.6, 95% confidence interval 1.0, 6.7) but not physical activity.
Both bone mineral density feedback and small group education delivered to mothers are effective at inducing maternally reported osteoporosis preventive behavior change in their children. These results require confirmation by studies with objective outcome measures.
Preventive Medicine 02/2006; 42(1):21-6. · 3.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Clinical trials have shown that calcium supplementation in children can increase bone mineral density (BMD) although this effect may not be maintained. There has been no quantitative systematic review of this intervention.
. To determine the effectiveness of calcium supplementation for improving BMD in children. . To determine if any effect varies by sex, pubertal stage, ethnicity or level of physical activity, and if any effect persists after supplementation is ceased.
We searched CENTRAL, (Cochrane Central Register of Controlled Trials) (Issue 3, 2005), MEDLINE (1966 to 1 April 2005), EMBASE (1980 to 1 April 2005), CINAHL (1982 to 1 April 2005), AMED (1985 to 1 April 2005), MANTIS (1880 to 1 April 2005) ISI Web of Science (1945 to 1 April 2005), Food Science and Technology Abstracts (1969 to 1 April 2005) and Human Nutrition (1982 to 1 April 2005). Conference abstract books (Osteoporosis International, Journal of Bone and Mineral Research) were hand-searched.
Randomised controlled trials of calcium supplementation (including by food sources) compared with placebo, with a treatment period of at least 3 months in children without co-existent medical conditions affecting bone metabolism. Outcomes had to include areal or volumetric BMD, bone mineral content (BMC), or in the case of studies using quantitative ultrasound, broadband ultrasound attenuation and ultrasonic speed of sound, measured after at least 6 months of follow-up.
Two authors independently assessed trial quality and extracted data including adverse events. We contacted study authors for additional information.
The 19 trials included 2859 participants, of which 1367 were randomised to supplementation and 1426 to placebo. There was no heterogeneity in the results of the main effects analyses to suggest that the studies were not comparable. There was no effect of calcium supplementation on femoral neck or lumbar spine BMD. There was a small effect on total body BMC (standardised mean difference (SMD) +0.14, 95% CI+0.01, +0.27) and upper limb BMD (SMD +0.14, 95%CI +0.04, +0.24). Only the effect in the upper limb persisted after supplementation ceased (SMD+0.14, 95%CI+0.01, +0.28). This effect is approximately equivalent to a 1.7% greater increase in supplemented groups, which at best would reduce absolute fracture risk in children by 0.1-0.2%per annum. There was no evidence of effect modification by baseline calcium intake, sex, ethnicity, physical activity or pubertal stage. Adverse events were reported infrequently and were minor.
While there is a small effect of calcium supplementation in the upper limb, the increase in BMD which results is unlikely to result in a clinically significant decrease in fracture risk. The results do not support the use of calcium supplementation in healthy children as a public health intervention. These results cannot be extrapolated to children with medical conditions affecting bone metabolism.
[Show abstract][Hide abstract] ABSTRACT: Cartilage defects are present in subjects with knee osteoarthritis (OA). Although they are often present in healthy subjects, there is little data on the natural history of cartilage defects. The aim of this study was to examine the change in cartilage defects over 2 yr and to identify factors associated with this change.
One hundred and twenty-four healthy subjects underwent magnetic resonance imaging of their dominant knee at baseline and follow-up. Cartilage defects were scored (0-4) at five sites. Bone size was determined at medial and lateral tibial plateau and patella. Height, weight, body mass index and physical activity were measured by standard protocols.
Eighty-six subjects completed the study. The mean cartilage defect score of each tibiofemoral compartment increased over time. However, medial and lateral tibiofemoral defect score decreased in 5% of the subjects. Cartilage defects were more likely to progress in males than females in each individual compartment (P<0.001 for medial tibiofemoral, P=0.005 for lateral tibiofemoral and P=0.01 for patellar cartilage). Baseline cartilage defect score was negatively associated with the progression of cartilage defects in each compartment (all P<0.001).
Although knee cartilage defects progressed over time in the majority of normal subjects, those of the highest severity tended to regress. Male gender and baseline cartilage defect score were the main factors associated with the progression of cartilage defects. Larger studies will be required to identify factors associated with the progression and regression of lesions.
[Show abstract][Hide abstract] ABSTRACT: To determine whether articular cartilage defects are associated with cartilage loss and joint replacement in subjects with symptomatic knee osteoarthritis (OA).
One hundred and seventeen subjects with symptomatic knee OA underwent magnetic resonance imaging of their dominant knee at baseline and 2 yr later. Cartilage defects were identified as prevalent (defect score > or =2) in each knee compartment. Occurrence of joint replacement by 4 yr was documented.
Cartilage defects were present in 81% of medial, 64% of lateral tibiofemoral compartments and 55% of patellar cartilages. Annual patellar cartilage loss was highest in those with defects compared with no defects (5.5% vs 3.2%, P = 0.01). Tibial cartilage loss was not associated with defects in the medial (4.6% vs 5.8%, P = 0.42) or lateral (4.7% vs 6.5%, P = 0.21) tibial cartilages. Higher total cartilage defect scores (8-15) were associated with a 6.0-fold increased risk of joint replacement over 4 yr compared with those with lower scores (2-7) (95% confidence interval 1.6, 22.3), independently of potential confounders.
Articular cartilage defects are associated with disease severity in knee OA and predict patellar cartilage loss and knee replacement.
[Show abstract][Hide abstract] ABSTRACT: Although the current recommendation is to measure radiographic joint space width (JSW) to assess structural change in osteoarthritis (OA), there is increasing interest in direct measurement of cartilage volume from magnetic resonance imaging (MRI). We performed a longitudinal study to compare change in both JSW and articular cartilage volume in subjects with symptomatic knee OA.
JSW was measured in 28 subjects with knee OA (57% females, mean age 62.8+/-9.8 years) who had standing radiographs in full extension, where both radiographs had satisfactory alignment. Each subject had femoral, tibial and combined femoral and tibial cartilage volumes determined from T1-weighted fat saturated sagittal knee MRI. All subjects had a repeat of the knee radiograph and MRI 1.96+/-0.4 years later.
At baseline there was a moderate, but statistically significant, correlation between JSW and femoral and tibial cartilage volumes in the medial tibiofemoral joint, which was strengthened by adjusting for medial tibial bone size (R=0.58-0.66, P=0.001). Although we observed a reduction in JSW and femoral and tibial cartilage volumes over the study period, there was no significant association between reduction in JSW and cartilage volume (R<0.13). There was a trend towards a significant association between change in medial tibiofemoral cartilage volume and joint replacement at 4 years (OR=9.0, P=0.07) but not change in medial tibiofemoral JSW (OR=1.1, P=0.92).
Although there was a modest correlation between cartilage volume and JSW in the medial tibiofemoral compartment, there was no correlation between longitudinal change in these measures. Change in cartilage volume appears to be a better predictor of joint replacement. Further work in larger samples over a longer period of time will be needed to confirm these findings.
Osteoarthritis and Cartilage 08/2005; 13(8):722-7. · 4.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To describe the associations between age, knee cartilage morphology, and bone size in adults.
A cross sectional convenience sample of 372 male and female subjects (mean age 45 years, range 26-61) was studied. Knee measures included a cartilage defect five site score (0-4 respectively) and prevalence (defect score of > or =2 at any site), cartilage volume and thickness, and bone surface area and/or volume. These were determined at the patellar, medial, and lateral tibial and femoral sites using T(1)weighted fat saturation MRI. Height, weight, and radiographic osteoarthritis (ROA) were measured by standard protocols.
In multivariate analysis, age was significantly associated with knee cartilage defect scores (beta = +0.016 to +0.073/year, all p<0.01) and prevalence (OR = 1.05-1.10/year, all p<0.05) in all compartments. Additionally, age was negatively associated with knee cartilage thickness at all sites (beta = -0.013 to -0.035 mm/year, all p<0.05), and with patellar (beta = -11.5 microl/year, p<0.01) but not tibial cartilage volume. Lastly, age was significantly positively associated with medial and lateral tibial surface bone area (beta = +3.0 to +4.7 mm(2)/year, all p<0.05) and patellar bone volume (beta = +34.4 microl/year, p<0.05). Associations between age and tibiofemoral cartilage defect score, cartilage thickness, and bone size decreased in magnitude after adjustment for ROA, suggesting these changes are directly relevant to OA.
The most consistent knee structural changes with increasing age are increase in cartilage defect severity and prevalence, cartilage thinning, and increase in bone size with inconsistent change in cartilage volume. Longitudinal studies are needed to determine which of these changes are primary and confirm their relevance to knee OA.
Annals of the Rheumatic Diseases 05/2005; 64(4):549-55. · 9.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During February 2003 Comet C/2002 V1 (NEAT) passed through the field-of-view (FOV) of the LASCO C3 coronagraph onboard SOHO. The comet passed within 0.1 AU (about 20 solar radii) of the Sun and displayed complex dust and ion tails. Observations of the comet's ion tail orientation have been used to estimate the solar wind speed while in the C3 FOV. We have used the Wang-Sheeley model to estimate the solar wind speed in the vicinity of the comet for comparison with the ion-tail results. The comet's orbit combined with solar rotation produced a comet track along the source surface at nearly constant Carrington longitude and heliographic latitudes ranging from 70 North to 40 South. Photospheric magnetic field maps from Carrington Rotation 1999 measured at three observatories (Wilcox, Kitt Peak, and Mt. Wilson) were used as inputs to the Wang-Sheeley model and each gave different placements of the current sheet. Two of the model results (Wilcox and Kitt Peak) placed the current sheet at similar latitudes (40-45 degrees North) while the third (Mt. Wilson) placed the current sheet at lower latitudes (20 degrees) and appeared to agreed with the current sheet placement implied by the ion-tail results. In this presentation we will discuss the methods of solar wind speed determination from ion-tail observations, present the comparison of solar wind speeds derived from the ion tail measurements with values derived from magnetic field observations, and discuss differences in photospheric magnetic field maps that could affect the location of the current sheet.