Volumetric bone mineral density and bone geometry assessed by peripheral quantitative computed tomography in women with differentiated thyroid cancer under TSH suppression.

OBJECTIVE: TSH suppression therapy in patients with differentiated thyroid cancer (DTC) has been associated with adverse effects on areal bone mineral density (aBMD) only in postmenopausal women. The purpose of study was to examine the effect of TSH suppression therapy on skeletal integrity using peripheral quantitative computed tomography (pQCT) at the radius and tibia in pre- and postmenopausal women with DTC and controls. STUDY DESIGN AND PATIENTS: Subjects included 80 women with DTC (40 pre- and 40 postmenopausal) and 89 (29 and 60, respectively) controls. pQCT was performed at the radius and tibia, Dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine, while samples were taken for calciotropic hormones and bone markers. RESULTS: No differences were observed concerning aBMD by DXA. In premenopausal women, there were no significant differences concerning vBMD, while cortical thickness was higher at the radius in patients with DTC (P < 0·01) compared with controls. In postmenopausal women with DTC trabecular bone mineral content (BMC), area and vBMD were lower at the radius (all P < 0·05), while at the tibia trabecular BMC and vBMD were lower at the mixed transition zone (14% from the distal end, P < 0·05) compared with controls. Cortical thickness was lower at the radius (P < 0·01) in postmenopausal patients compared with controls. Serum CTX was higher in postmenopausal women with DCT (P < 0·01), while in premenopausal patients, parathyroid hormone (PTH) was lower (P = 0·01) compared with controls. CONCLUSIONS: TSH suppression therapy is associated with higher bone resorption only in postmenopausal women; this adversely affects trabecular and cortical bone properties especially at nonweight-bearing sites such as the radius.

Physical activity is associated with bone geometry of premenarcheal girls in a dose-dependent manner.

OBJECTIVE: To determine the relationship between habitual physical activity (PA) level and peripheral qualitative computed tomography-determined quantitative tibia characteristics of premenarcheal girls. METHODS: Premenarcheal girls matched for age (10-13 years), bone age and maturity level were assigned into: a) low PA group (LPA, n=25), b) moderate PA group (MPA, n=17), and c) high PA group (HPA, n=18). Participants' daily dietary intake, tibia's geometry and serum levels of calcium and vitamin D were assessed. RESULTS: Premenarcheal girls demonstrating HPA exhibited greater pericortical thickness, cross-sectional area (CSA) and bone mineral content (BMC) (p<.001) in cortical bone, greater BMC, volumetric bone density (vBMD) and polar stress strength index (SSIp) in trabecular bone (p<0.001-0.05) and greater total BMC (p<.05) and vBMD (p<.01) when compared to their physically inactive or moderately active counterparts. MPA exhibited greater values of cortical BMC (p<.01) and SSIp (p<.05) than LPA. Partial correlation analysis (adjusted for BMI) revealed modest associations between PA score and bone geometry parameters (r=0.36-0.49, p<.05) at 38% of tibia length. CONCLUSIONS: Habitual PA affects geometry of both cortical and trabecular areas of a long bone of premenarcheal girls in a dose-dependent manner. Specifically, PA increases both the density and size of cortical bone but only the density of trabecular bone during preadolescence. Given the importance of peak bone mass for future fracture risk, high levels of PA during childhood could be a major target for public health interventions aimed at optimising bone health in prepubertal children when the greatest bone gains occur.

Assessment of musculoskeletal system in women with jumping mechanography.

The purpose of this study was to investigate and add reference data about the musculoskeletal system in women. The mechanography system of the Leonardo™ platform (Novotec, Germany) was used to measure parameters of movement (velocity, force, power) in 176 healthy Greek women aged 20-79 years, separated according to age decade in six groups: group 1 (n = 12), 20-29 years; group 2 (n = 14), 30-39 years; group 3 (n = 33), 40-49 years; group 4 (n = 59), 50-59 years including 21 postmenopausal; group 5 (n = 31), 60-69 years including 12 postmenopausal; and group 6 (n = 27), 70-79 years all postmenopausal. This system measures forces applied to the plate over time, calculates through acceleration the vertical velocity of center of gravity and using force and velocity it calculates power of vertical movements. All women performed a counter-movement jump (brief squat before the jump) with freely moving arms. Weight was recorded on the platform before the jump and height was measured with a wall-mounted ruler. Body weight and body mass index were gradually increased; on the contrary height and all movement parameters except force (velocity, power) were statistically decreased during aging and after menopause.

Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound.

BACKGROUND: Interventions other than medications in the management of osteoporosis are often overlooked. The purpose of this study was to investigate the association of physical activity and calcium intake with bone parameters. METHODS: We measured the heel T-score and stiffness index (SI) in 1890 pre- and postmenopausal women by quantitative ultrasound (QUS) and assessed physical activity and dietary calcium intake by questionnaire. Participants were divided according to their weekly physical activity (sedentary, moderately active, systematically active) and daily calcium consumption (greater than or less than 800 mg/day). RESULTS: SI values were significantly different among premenopausal groups (p = 0.016) and between sedentary and systematically active postmenopausal women (p = 0.039). QUS T-scores in systematically active premenopausal women with daily calcium intake > 800 mg/day were significantly higher than those in all other activity groups (p < 0.05) independent of calcium consumption. CONCLUSIONS: Systematic physical activity and adequate dietary calcium intake are indicated for women as a means to maximize bone status benefits.

Correlation of pQCT bone strength index with mechanical testing in distraction osteogenesis.

Distraction osteogenesis is an established method of treatment of non-unions and limb length discrepancies. Despite improvements in surgical techniques and fixation devices there is still a considerable possibility of failure of the regenerate bone after frame removal. The hypothesis of the present experimental study was that a noninvasive bone strength marker, the strength-strain index (SSI) measured by peripheral quantitative computerized tomography (pQCT), could be significantly correlated with a biomechanical bone strength index, the maximum load at bone failure (F(max)), assessed in a three-point bending test. The right tibias of fifteen male New Zealand White rabbits were subjected to gradual lengthening using an external fixator. At the end of the consolidation phase (55th day) the animals were sacrificed and the lengthened tibiae were collected free of soft tissue, after removal of the lengthener, for immediate scanning and mechanical testing. The values of cortical bone mineral density, cortical bone area, and the corresponding SSIy, as measured by pQCT, were assessed for statistically significant correlation relative to the values of the F(max) and stiffness as evaluated by the three-point bending test were assessed. SSIy showed a statistically significant positive correlation with the maximum load (F(max)) with a correlation value R=0.846 (p<0.001), and it was a good predictor of F(max) since it was able to describe the 71.6% of variability of F(max)(R2=0.716). Furthermore, cortical bone area appeared to be highly correlated with F(max) (p<0.005), but it was a less efficient predictor of F(max) (R2=0.471). There was, also, a statistically significant correlation between SSIy and bone stiffness as assessed in the 3-point bending test (p<0.005). In conclusion, the present study reveals that the SSI can be used as a sensitive index of adequate consolidation of the regenerate bone, possibly able to reduce mechanical failure due to premature frame removal. In clinical relevance, the aforementioned hypothesis should be applied in studies of human populations and possible confirmation of its validity would establish pQCT as a valuable diagnostic tool not only in distraction osteogenesis but also in other techniques of bone healing.

Body composition in paraplegic men.

To investigate alterations in the body composition of paraplegic men, 31 complete paraplegic men thoracic (T)4-T 12 neurological level of injury, 16 with paraplegia above (high), and 15 below (low) thoracic 7, were compared with 33 able-bodied men. Whole body dual X-ray absorptiometry was used to estimate regional (arms, legs) and total body bone mineral density (g/cm(2)), lean, and fat mass (g).The influence of the neurological level of injury and the duration of paralysis in relation with the above parameters were also investigated. Body mass index, bone mineral density, and lean mass were significantly decreased (p < 0.0005) and fat mass was increased (p < 0.05) in the legs and total body composition in paraplegics. Bone mineral density was significantly lower in high paraplegics' arms compared with low paraplegics (p = 0.028). The correlation of body mass index with fat mass was statistically significant in all paraplegics and controls (r = 0.57, p = 0.001 and r = 0.73, p = 0.0001, respectively) and in low paraplegics (r = 0.72, p = 0.004). Legs' bone mineral density and arms' fat mass were correlated with the duration of paralysis in all paraplegics (r = -0.46, p = 0.009 and r = 0.43, p = 0.020, respectively) and in high paraplegics (r = 0.73, p = 0.001 and r = 0.55, p = 0.042, respectively). Total fat mass was correlated with the duration of paralysis in high paraplegics (r = 0.5, p = 0.05). These results suggest body composition changes in paraplegics.

Calcitonin administration in a rabbit distraction osteogenesis model.

The effect of salmon calcitonin on the maturation of the regenerate bone was assessed in an experimental model in rabbits. Twenty-six New Zealand White male rabbits, approximately 5 months old and weighing 3 to 3.5 kg, were subjected to a mid-diaphyseal tibial osteotomy. After 5 days, the right tibia was lengthened gradually at a rate of 0.375 mm every 12 hours, for 10 days. Ten international units of salmon calcitonin were administered daily subcutaneously to the study group (14 animals), whereas the animals of the control group (12 animals) were injected with a placebo, for the duration of the experiment. The bone mineral density of the regenerate bone was assessed on Days 20, 35, 45, and 55 of the experiment, in both groups, using dual energy xray absorptiometry. No statistical significant difference was found in the dual energy xray absorptiometry measurements between the study and control groups regarding the change of the bone mineral density of the new bone relative to a preoperative baseline measurement. Characteristic time-related changes were observed in the bone mineral density of the regenerate bone during its maturation, which proved to be identical in both groups. It seems that the administration of calcitonin does not enhance regenerate bone mineralization rate and tendency during bone lengthening.