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Biomedical subjects

Graeme Jones

Publications and source records attributed to Graeme Jones.

At least 37 records · Page 2Linked to original sources
PubMed2005

Reduced bone density in children on long-term warfarin.

Vitamin K is essential for development of normal bone density and achieving adequate peak bone mass in childhood and is thought to be important in preventing the development of osteoporosis in later life. Warfarin, a vitamin K antagonist, is being used with greater frequency in children. The long-term effect of warfarin on bone density of children is not known. We performed a case control study survey of bone density in children on long-term warfarin (n=17, average duration of warfarin treatment 8.2 y) compared with randomly selected controls (n=321). There was a marked reduction in bone mineral apparent density of lumbar spine between patients and controls [patients 0.10 g/cm3; 95% confidence interval (CI), 0.93-0.11 g/cm3, controls 0.12 g/cm3; 95% CI, 0.11-0.12 g/cm3, p<0.001). The lumbar spine areal bone mineral density Z-score of patients was reduced compared with controls [patients, -1.96 (95% CI, -2.52 to -1.40). This difference persisted after adjustment for age and body size. The etiology for the reduced bone density is likely to be multifactorial, however, screening of children on long-term warfarin for reduced bone density should be considered.

Adolescent↗
PubMed2005

Factors associated with hip cartilage volume measured by magnetic resonance imaging: the Tasmanian Older Adult Cohort Study.

OBJECTIVE: To compare associations between anthropometric and lifestyle factors and femoral head cartilage volume/thickness and radiographic features of osteoarthritis (OA) and to provide evidence of construct validity for magnetic resonance imaging (MRI) assessment of femoral cartilage volume and thickness. METHODS: We studied a cross-sectional sample of 151 randomly selected subjects (79 men, 72 women; mean age 63 years) from the Tasmanian Older Adult Cohort Study. A sagittal T1-weighted fat-suppression MRI scan of the right hip was performed to determine femoral head cartilage volume, cartilage thickness, and size. An anteroposterior radiograph of the pelvis with weight bearing was performed and scored for radiographic evidence of OA in the right hip. Other factors measured were height, weight, leg strength, serum vitamin D levels, and bone mineral density. RESULTS: Hip cartilage volume was significantly associated with female sex, body mass index, and femoral head size, whereas hip cartilage thickness was significantly associated only with the size of the femoral head. Only female sex was significantly associated with the total radiographic OA score and the joint space narrowing (JSN) score, but not the osteophyte score. Radiographic JSN of the hip, especially axial JSN (but not osteophytes), was significantly correlated with hip cartilage volume and thickness. CONCLUSION: Femoral head cartilage volume and thickness have modest but significant construct validity when correlated with radiographic findings. Furthermore, the generally stronger associations with volume compared with radiographic OA suggest that MRI may be superior at identifying risk factors for hip OA.

Aged↗
PubMed2005

Association of cartilage defects with loss of knee cartilage in healthy, middle-age adults: a prospective study.

OBJECTIVE: The significance of asymptomatic knee cartilage defects in healthy individuals is not known. The aim of this study was to examine the association between cartilage defects in the knee and cartilage volume both cross-sectionally and longitudinally in healthy, middle-age adults. METHODS: Eighty-six healthy men and women (mean +/- SD age 53.8 +/- 8.8 years) underwent T1-weighted fat-suppressed magnetic resonance imaging of their dominant knees at baseline and at the 2-year followup visit. Knee cartilage volume was measured. Cartilage defects were scored according to a grading system (0-4) and as present (a defect score of > or = 2) or absent in the medial and lateral tibiofemoral compartments. RESULTS: Cartilage defects in the medial and lateral tibiofemoral compartments were very common (in 61% and 43% of subjects, respectively). Those with cartilage defects had a 25% reduction in medial tibial cartilage volume, a 15% reduction in lateral tibial cartilage volume, and a 19% reduction in total femoral cartilage volume relative to those with no cartilage defects in cross-sectional analyses (all P < 0.05). In the medial tibiofemoral compartment, the annual loss of tibial cartilage in those with cartilage defects was 2.5% (95% confidence interval [95% CI] 2.2%, 3.1%) compared with an annual loss of tibial cartilage of 1.3% (95% CI 0.5%, 2.0%) in those with no defects (P = 0.028), independent of other known risk factors for osteoarthritis (OA). CONCLUSION: These data suggest that the presence of asymptomatic, non-full-thickness medial tibiofemoral cartilage defects identifies healthy individuals most likely to lose knee cartilage in the absence of radiographic knee OA. Thus, interventions aimed at reducing or reversing cartilage defects may reduce the risk of subsequent knee OA.

Australia↗
PubMed2005

The genetic contribution to longitudinal changes in knee structure and muscle strength: a sibpair study.

OBJECTIVE: To estimate the heritability of longitudinal changes in knee cartilage volume, chondral defects, subchondral bone size, and lower limb muscle strength. METHODS: A sibpair design was used. Longitudinal changes in lateral and medial tibial cartilage volume and bone size, as well as progression of chondral defects, were determined on serial magnetic resonance images. Radiographs were obtained and scored for individual features of radiographic osteoarthritis (OA) at baseline. Lower limb muscle strength was measured by dynamometry. Heritability was estimated using the SOLAR software package. RESULTS: A total of 115 subjects (55 men and 60 women, mean age 45 years) from 48 families representing 95 sibling pairs were successfully followed up for a mean of 2.4 years. The adjusted heritability estimates for changes in cartilage volume were 73% for the medial compartment (P < 0.01) and 40% for the lateral compartment (P = 0.10). The adjusted heritability estimates for changes in bone size were 62% for the lateral compartment (P = 0.03) and 20% for the medial compartment (P = 0.22). The adjusted heritability estimate for changes in muscle strength was 64% (P = 0.01). The adjusted heritability estimates for progression of chondral defects were 80% for the lateral compartment (P = 0.06) and 98% for the medial compartment (P = 0.03). These estimates changed little after adjusting for each other and for the predominantly mild radiographic OA, with the exception of progression of chondral defects in the lateral compartment. CONCLUSION: Early longitudinal changes in knee structures of relevance to later OA, such as changes in medial tibial cartilage volume, lateral tibial bone size, progression of chondral defects, and muscle strength, have high heritability, most likely reflecting a strong genetic component and suggesting their potential to be studied in quantitative trait linkage and association analysis.

Adult↗
PubMed2005

Association of prevalent and incident knee cartilage defects with loss of tibial and patellar cartilage: a longitudinal study.

OBJECTIVE: To describe the association between prevalent and incident knee cartilage defects and loss of knee cartilage in male and female adults. METHODS: A convenience sample of 325 subjects (mean age 45 years; age range 26-61 years) was evaluated at baseline and approximately 2 years later. Knee cartilage volume, cartilage defect scores (0-4 scale), and joint surface area were determined using T1-weighted fat-suppression magnetic resonance imaging techniques. Height, weight, and radiographic evidence of osteoarthritis were measured by standard protocols. RESULTS: Multivariable analysis revealed that baseline cartilage defect scores at the medial tibia, lateral tibia, and patella had a dose-response association with the annual rate of change in knee cartilage volume at the corresponding site (beta = -1.3% to -1.2% per grade; P < 0.05 for all comparisons). In addition, an increase in knee cartilage defect score (change of > or =1) was associated with higher rates of knee cartilage volume loss at all sites (beta = -1.9% to -1.7% per year; P < 0.01 for all comparisons). Furthermore, a decrease in the knee cartilage defect score (change of less than or equal to -1) was associated with an increase in knee cartilage volume at all sites (beta = 1.0% to 2.7% per year; P < 0.05 for all comparisons). CONCLUSION: Prevalent knee cartilage defects are predictive of compartment-specific cartilage loss over 2 years. Both increases and decreases in knee cartilage defects are associated with changes in knee cartilage volume, which implies a potential for reversal of knee cartilage loss.

Adult↗
PubMed2005

Skeletal age deviation assessed by the Tanner-Whitehouse 2 method is associated with bone mass and fracture risk in children.

The aim of this population-based case-control study was to describe the association among skeletal age deviation (SAD), bone density, and upper limb fracture risk in male and female children aged 9-16 years. A total of 321 fracture cases and 321 randomly selected individually matched controls were studied. Skeletal age was assessed by standard atlas. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) and metacarpal index (MI). There were no significant differences in mean skeletal age or chronological age between fracture cases and controls. However, SAD was associated with total, hand, and female fracture risk (all P<0.05). The fracture associations became nonsignificant after adjustment for BMD and MI in all subgroups with the exception of hand fractures (OR, 0.67/year; 95% CI, 0.47-0.96). SAD was also positively associated with BMD at all sites (r=0.33-0.35, all P<0.05) and MI (r=0.20, P<0.05). The strength of association reduced but remained significant at most sites after adjustment for body size, maturity, age, and sex. In conclusion, SAD is positively associated with measures of bone strength and negatively associated with upper limb fracture risk (especially those of the hand) in children. SAD is simple to measure and gives additional information regarding bone health and fracture risk in children.

Adolescent↗
PubMed2005

Knee cartilage defects: association with early radiographic osteoarthritis, decreased cartilage volume, increased joint surface area and type II collagen breakdown.

OBJECTIVE: To generate hypotheses regarding the associations between knee cartilage defects and knee radiographic osteoarthritis (ROA), cartilage volume, bone size and type II collagen breakdown in adults. METHODS: A cross-sectional convenience sample of 372 male and female subjects (mean age 45 years, range 26-61) was studied. Knee cartilage defect score (0-4) and prevalence (a defect score of > or =2), cartilage volume, and bone surface area were determined using T1-weighted fat saturation MRI. Urinary levels of C-terminal crosslinking telopeptide of type II collagen (U-CTX-II) were measured by enzyme-linked immunosorbent assay. Height, weight and ROA were measured by standard protocols. RESULTS: In multivariate analysis, the severity and prevalence of knee cartilage defects were significantly and independently associated with tibiofemoral osteophytes (regression coefficient (beta): +0.86 to +1.31/unit, odds ratio (OR): 2.97-3.68/unit, all P<0.05 with the exception of OR in lateral tibiofemoral compartment) and tibial bone area (beta: +0.11 to +0.25/cm2; OR: 1.33-1.58/cm2, all P<0.01). Knee cartilage defects were inconsistently associated with joint space narrowing after adjustment for osteophytes but consistently with knee cartilage volume (beta: -0.27 to -0.70/ml; OR: 0.16-0.56/ml, all P<0.01 except for OR at lateral tibial cartilage site P=0.06). Lastly, knee cartilage defect severity was significantly associated with U-CTX-II (Partial r=+0.18, P<0.001 for total cartilage defect score). CONCLUSION: Osteophytes and increasing knee bone size may be causally related to knee cartilage defects. Furthermore, knee cartilage defects may result in increased cartilage breakdown leading to decreased cartilage volume and joint space narrowing suggesting an important role for knee cartilage defects in early knee OA.

Adult↗
PubMed2005

A meta-analysis of sex differences prevalence, incidence and severity of osteoarthritis.

OBJECTIVE: To resolve uncertainty regarding sex differences in osteoarthritis (OA) by performing a meta-analysis of sex differences in OA prevalence, incidence and severity. METHODS: Standard search strategies for population-based studies of OA providing sex-specific data. Random effects meta-analysis to provide pooled male vs female risk and rate ratios for prevalent and incident OA, and standardized mean differences (SMD) for OA severity. Meta-regression was used to investigate sources of heterogeneity. RESULTS: Males had a significantly reduced risk for prevalent OA in the knee [Risk Ratio (RR) 0.63, 95% CI 0.53-0.75] and hand [RR 0.81, 95% CI 0.73-0.90] but not for other sites. Males aged <55 years had a greater risk of prevalent cervical spine OA [RR 1.29, 95% CI 1.18-1.41]. Males also had significantly reduced rates of incident OA in the knee [Incidence Rate Ratio (IRR) 0.55, 95% CI 0.32-0.94] and hip [IRR 0.64, 95% CI 0.48-0.86], with a trend for hand [IRR 0.65, 95% confidence interval (CI) 0.35-1.20]. Females, particularly those > or = 55 years, tended to have more severe OA in the knee but not other sites. Heterogeneity in the estimates of sex differences in prevalence was substantially explained by age and other study design factors including method of OA definition. CONCLUSIONS: The results demonstrate the presence of sex differences in OA prevalence and incidence, with females generally at a higher risk. Females also tend to have more severe knee OA, particularly after menopausal age. The site differences indicate the need for further studies to explore mechanisms underlying OA.

Age Factors↗
PubMed2005

Knee structural alteration and BMI: a cross-sectional study.

OBJECTIVE: To describe the associations among BMI, knee cartilage morphology, and bone size in adults. RESEARCH METHODS AND PROCEDURES: A cross-sectional convenience sample of 372 male and female subjects (mean age, 45 years; range, 26 to 61 years) was studied. Knee articular cartilage defect score (0 to 4) and prevalence (defect score of >/=2), volume, and thickness, as well as bone surface area and/or volume, were determined at the patellar, tibial, and femoral sites using T1-weighted fat-saturation magnetic resonance imaging. Height, weight, BMI, and radiographic osteoarthritis were measured by standard protocols. RESULTS: In multivariate analysis in the whole group, BMI was significantly associated with knee cartilage defect scores (beta: +0.016/kg/m(2) to +0.083/kg/m(2), all p < 0.05) and prevalence (odds ratio: 1.05 to 1.12/kg/m(2), all p < 0.05 except for the lateral tibiofemoral compartment). In addition, BMI was negatively associated with patellar cartilage thickness only (beta = -0.021 mm/kg/m(2); p = 0.039) and was positively associated with tibial bone area (medial: beta = +7.1 mm(2)/kg/m(2), p = 0.001; lateral: beta = +3.2 mm(2)/kg/m(2), p = 0.037). Those who were obese also had higher knee cartilage defect severity and prevalence and larger medial tibial bone area but no significant change in cartilage volume or thickness compared with those of normal weight. DISCUSSION: This study suggests that knee cartilage defects and tibial bone enlargement are the main structural changes associated with increasing BMI particularly in women. Preventing these changes may prevent knee osteoarthritis in overweight and obese subjects.

Adult↗
PubMed2005

The genetic contribution and relevance of knee cartilage defects: case-control and sib-pair studies.

OBJECTIVE: To describe the differences in knee cartilage defects between offspring of subjects with at least one parent with a total knee replacement for severe primary knee osteoarthritis (OA) and controls; and to estimate the heritability of knee cartilage defects in sib-pairs. METHODS: Population based, case-control study of 186 matched pairs (mean age 45 yrs, range 26-61) and sib-pair study of 128 subjects from 51 families (115 sib-pairs) within the case-control study. Knee cartilage defect scores (0-4) and prevalence (a cartilage defect score > or = 2) were assessed at the patellar, tibial, and femoral sites by processing images acquired using T1 weighted fat-saturated magnetic resonance imaging. Heritability was estimated using the SOLAR genetic analysis program. RESULTS: The prevalence of knee cartilage defects was surprisingly high (50% scored > or = 2 in any site). Compared to controls, offspring had higher knee cartilage defect scores and prevalence in tibiofemoral (4.39 vs 4.01, p = 0.003; 41% vs 28%, p = 0.009), patellar (1.32 vs 1.10, p = 0.031; 35% vs 26%, p = 0.075), and whole (5.71 vs 5.10, p = 0.002; 57% vs 42%, p = 0.007) compartments. These all became nonsignificant after adjustment for knee pain and radiographic OA. In the sib-pair component, knee cartilage defects had heritability for scores and prevalence, respectively, of 38% (p = 0.072) and 47% (p = 0.082) for tibiofemoral, 52% (p = 0.009) and 78% (p = 0.025) for patellar, and 43% (p = 0.038) and 68% (p = 0.072) for the whole compartments. These estimates became weaker at tibiofemoral and whole compartments after adjustment for bone size, knee pain, and radiographic OA. CONCLUSION: Knee cartilage defects are common, have a genetic component that is linked to the genetic contribution to knee pain and bone size, and may have a role in the genetic pathogenesis of knee OA.

Adult↗
PubMed2004

Vitamin D insufficiency in adolescent males in Southern Tasmania: prevalence, determinants, and relationship to bone turnover markers.

There are limited data on vitamin D insufficiency in healthy children. The aim of this study was to describe the prevalence and determinants of vitamin D insufficiency and its association with bone turnover in adolescent boys (N = 136, mean age 16 years). Sun exposure and physical activity were assessed by questionnaire. Vitamin D stores were assessed by serum 25-hydroxyvitamin D3 (25[OH]D3). Bone turnover was assessed by bone-specific alkaline phosphatase (BAP) and urinary pyridinoline (PYR) to creatinine (Cr) ratio (mmol PYR/micromol Cr). The mean 25(OH)D3 level was low (44 nmol/l; 68% < 50 nmol/l; range, 16-87) and was associated with self-reported sun exposure on winter weekends (r = 0.23, p = 0.01), school holidays (r = 0.22, p = 0.01), and weekdays (r = 0.17, p = 0.05). It was also associated with number of sports (r = 0.34, p < 0.001) and vigorous activity (r = 0.22, p = 0.01) but not television, computer, and video watching (r = -0.04, p = 0.68). In multivariate analysis, number of sports but not total sun exposure remained significantly associated with 25(OH)D3. Furthermore, 25(OH)D3 was significantly associated with BAP in cutpoint analysis (cutpoint 55 nmol/l, p = 0.03) but not continuous analysis (r = -0.12, p = 0.16) and PYR in both forms (r = -0.23, p = 0.01, cutpoint 43 nmol/l, p = 0.01). In conclusion, vitamin D insufficiency is common in healthy adolescent boys in winter in our setting, is primarily derived from sports-related sun exposure, and is associated with bone turnover markers. These data suggest that a 25(OH)D3 level of at least 43-55 nmol/l is required for optimal bone health in children.

Adolescent↗
PubMed2004

Risk-taking, coordination and upper limb fractures in children: a population based case-control study.

The aim of this population based case-control study was to examine the association between risk-taking behaviour, motor coordination and upper limb fractures in children aged 9-16 years. A total of 321 fracture cases and 321 randomly selected individually matched controls were studied. The number for different types of upper limb fractures was 91 for hand, 190 for wrist and forearm and 40 for upper arm. Risk-taking behaviour was determined by a 5-item interview-administered questionnaire. Motor coordination was assessed by the 8-point movement ABC that tests manual dexterity, ball skills as well as static and dynamic balance. Bone mass was assessed by dual energy X-ray absorptiometry (DXA) and metacarpal morphometry. In general, there was heterogeneity by fracture site with regard to associations. Risk-taking behaviour was associated with hand fracture risk but not other fracture sites for downhill cycling behaviour (OR: 2.0/category, 95% CI: 1.1-3.7), dare behaviour (OR: 3.3/category, 95% CI: 1.1-10.0) and total risk-taking score (OR: 2.6/category, 95% CI: 1.3-5.7). Conversely, coordination measures were associated with wrist and forearm fractures only: cutting/threading (OR: 1.2/unit, 95% CI: 1.0-1.4); flower trail (OR: 1.2/unit, 95% CI: 1.0-1.4) and dynamic balance score (OR: 1.1/unit, 95% CI: 1.0-1.2). Backward stepwise analysis selected total risk taking score for hand fracture, and dynamic balance score for wrist and forearm fracture. None of the risk-taking or coordination scores were associated with upper arm fractures. These associations were unchanged following adjustment for bone mass. In conclusion, the propensity to take risks is most strongly associated with hand fracture risk while dynamic balance is most strongly associated with wrist and forearm fracture risk in children. These results inform the development of fracture prevention strategies in children.

Adolescent↗
PubMed2004

The genetic contribution to muscle strength, knee pain, cartilage volume, bone size, and radiographic osteoarthritis: a sibpair study.

OBJECTIVE: To estimate the heritability of muscle strength, knee pain, cartilage volume, bone size, and radiographic osteoarthritis (ROA), and to assess whether heritability of the knee structural components is independent of ROA. METHODS: A sibpair design was utilized. Sagittal T1-weighted fat-suppressed magnetic resonance imaging (MRI) of the right knee was performed to determine cartilage volume and bone size. Standing semiflexed radiographs of the same knee were obtained to assess the presence of ROA. Knee pain was assessed by questionnaire and muscle strength by dynamometry. Heritability was estimated using the genetic analysis program SOLAR. RESULTS: A total of 128 subjects (61 men, 67 women; mean age 45 years) from 51 families representing 115 sibpairs were studied. Lower limb muscle strength had high heritability (42%; P = 0.02), as did knee pain (44%; P = 0.07). Heritability estimates for cartilage volume were 65% for medial tibial cartilage, 77% for lateral tibial cartilage, and 84% for patellar cartilage, and heritability estimates for bone size were 85% for medial tibial bone area, 57% for lateral tibial bone area, and 70% for patella bone volume (all P < or = 0.004). For ROA, heritability was 61% for presence (with a large standard error) (P = 0.16) and 61% for severity (P = 0.02). The estimates for tibial bone areas were the only ones markedly reduced after adjustment for body size, while all estimates with the exception of knee pain were independent of ROA. Cartilage and, to a lesser extent, bone sites investigated by MRI were largely under independent genetic control, with a lesser shared genetic component. CONCLUSION: With the exception of prevalent ROA, all knee modalities assessed had high heritability, most likely reflecting a strong genetic component. Cartilage volume, bone size, and muscle strength all have the potential to be studied in quantitative trait linkage analyses, but their exact relevance with regard to OA remains uncertain at this time.

Adult↗
PubMed2004

Growth, children, and fractures.

Fractures in childhood have long been considered an unavoidable consequence of growth. Studies in recent years have documented the epidemiology of these very common fractures and have also documented considerable variation by fracture type and from country to country. There have also been a number of studies aimed at identifying risk factors particularly for the most common distal forearm fracture. These studies have consistently associated bone mineral density with these fractures. Other possible risk factors include obesity, physical inactivity, sports, cola beverages, calcium intake, risk taking, and coordination. While prospective studies are required to confirm these risk factors, accumulating evidence now suggests that a substantial proportion of fractures in children are preventable.

Adolescent↗
PubMed2004

Developing a conceptual understanding of rural health practice.

OBJECTIVE: This study presents a set of concepts underpinning rural practice that could assist teaching health and medical students. OUTCOME: Five concepts, important in distinguishing rural health practice, are presented and discussed. These are rural-urban health differentials, access, confidentiality, cultural safety and team practice. Together these concepts impact the ways in which rural health professionals provide care, due to fewer services, greater distances, smaller populations, less choice of services and smaller workforce. CONCLUSION: These concepts introduce students to some of the positive and negative aspects of rural practice, as well as opportunities for rural practitioners to have a diverse practice, to become involved in all aspects of health and to initiate change. They provide an understanding of rurality from which health students can learn from their practical experiences during rural placements.

Attitude of Health Personnel↗