Effect of rhythmic gymnastics on volumetric bone mineral density and bone geometry in premenarcheal female athletes and controls.

CONTEXT AND OBJECTIVE: Weight-bearing exercise during growth exerts positive effects on the skeleton. Our objective was to test the hypothesis that long-term elite rhythmic gymnastics exerts positive effects on volumetric bone mineral density and geometry and to determine whether exercise-induced bone adaptation is associated with increased periosteal bone formation or medullary contraction using tibial peripheral quantitative computed tomography and bone turnover markers. DESIGN AND SETTING: We conducted a cross-sectional study at a tertiary center. SUBJECTS: We studied 26 elite premenarcheal female rhythmic gymnasts (RG) and 23 female controls, aged 9-13 yr. MAIN OUTCOME MEASURES: We measured bone age, volumetric bone mineral density, bone mineral content (BMC), cortical thickness, cortical and trabecular area, and polar stress strength index (SSIp) by peripheral quantitative computed tomography of the left tibia proximal to the distal metaphysis (trabecular) at 14, 38 (cortical), and 66% (muscle mass) from the distal end and bone turnover markers. RESULTS: The two groups were comparable according to height and chronological and bone age. After weight adjustment, cortical BMC, area, and thickness at 38% were significantly higher in RG (P < 0.005-0.001). Periosteal circumference, SSIp, and muscle area were higher in RG (P < 0.01-0.001). Muscle area was significantly associated with cortical BMC, area, and SSIp, whereas years of training showed positive association with cortical BMC, area, and thickness independent of chronological age. CONCLUSIONS: RG in premenarcheal girls may induce positive adaptations on the skeleton, especially in cortical bone. Increased duration of exercise is associated with a positive response of bone geometry.

Bone loss and mechanical properties of tibia in spinal cord injured men.

AIM: The effects of Spinal Cord Injury (SCI) on bone in paralyzed areas are well documented but there are few data for the importance of the level of injury in the decrease of mechanical strength in paralyzed legs. The aim of the present study was to describe bone loss of the separate compartments of trabecular and cortical bone in spinal cord injured men and to compare possible changes in mechanical properties of tibia with the neurological level of injury. MATERIALS AND METHODS: Fifty men were included in this study: 39 had complete SCI in chronic stage. As chronic stage, we considered paraplegia >1.5 years (yrs). Men were separated as follows: Group A (18 men, high paraplegia: Thoracic (T)4-T7 level, mean age: 33 yrs, duration of paralysis: 5.9 yrs) and group B (21 men, low paraplegia: T8-T12 level, mean age: 39 yrs, duration of paralysis: 5.6 yrs) in comparison with 11 healthy men as a control group (C) of similar age, height, and weight. None of the subjects was given bone acting drugs. The neurological profile of each patient was assessed according to the American Spinal Injury Association (ASIA). All subjects were measured by peripheral quantitative computed tomography (pQCT). Measurements were performed at the tibia with a Stratec XCT 3000 (Stratec Medizintechnik, Pforzheim, Germany) scanner. The distal end of the tibia was used as an anatomical marker. The bone parameters, bone mass density (BMD) trabecular, BMD total, BMD cortical, and cortical thickness have been measured at 4% and 38%, respectively, of the tibia length proximal to this point, and the periosteal and endocortical was measured at 14% of the tibia. We calculated stress strain index (SSI), a bone strength estimator derived from the section modulus, and the volumetric density of the cortical area at 14% (SSIPol2) and 38% (SSIPol3) of the tibia length proximal to the distal end of the tibia. RESULTS: In both groups A and B most bone mass parameters were statistically decreased in comparison with controls. In each group we calculated the median deltaSSI(3-2) (SSIPol3 - SSIPol2). In the paraplegic groups Spearman correlation coefficient between duration of paralysis and deltaSSI(3-2) was in group A: r=-0.178, p=N.S. and group B: r=0.534, p=0.027, respectively. CONCLUSION: Despite the similar paralytic effect on bone in all paraplegic patients in our study and because of the non-significant duration of paralysis between paraplegic groups (p=0.87), the two paraplegic groups act differently in mechanical properties of the tibia. In addition, group A patients in respect to the level of injury, are susceptible to autonomic dysreflexia as a result of the disruption of the autonomic nervous system pathways. These results suggest that neurogenic factors are influencing geometric bone parameters.

Clinical practice guidelines proposed by the Hellenic Foundation of Osteoporosis for the management of osteoporosis based on DXA results.

In recent years guidelines for the testing and treatment of osteoporotic patients have been published by recognised organisations, including the World Health Organisation (WHO), the National Osteoporosis Foundation (NOF) and the International Osteoporosis Foundation (IOF). Dual Energy X-ray Absorptiometry (DXA) has been considered the technique of choice because of its excellent precision and ability to predict osteoporotic fractures. Last December, based on the Appraisal of the Guidelines for Research and Evaluation (AGREE), the Hellenic Foundation of Osteoporosis, in collaboration with other scientific societies, provided guidelines for the use of DXA for the diagnosis, monitoring and treatment of osteoporosis and Quality Assurance (QA) of these systems. According to these guidelines, the adequacy of the present number of DXA units in Greece was assessed. There are 367 DXA units in Greece, and almost 50% are located in the capital city, Athens, where 34.1% of the population lives. The distribution of DXA devices per resident in the Greek provinces (except Attica) is between 4.2 units/100,000 heads (Ionian Islands) and 1.6 units/100,000 heads (Sterea Hellas). These guidelines have resulted in a suggestive yearly repeat of the measurements, to ensure the precision of the method, but mainly for reasons of compliance. Finally, these guidelines are viewed as a work in progress and will be updated periodically in response to advances in this field.

A randomized trial of nasal spray salmon calcitonin in men with idiopathic osteoporosis: effects on bone mineral density and bone markers.

In a 12-month randomized, double-blind, placebo-controlled trial, we have studied the effects of intranasal salmon calcitonin (SCT) on bone mineral density (BMD) and biochemical markers of bone turnover. Twenty-eight men with idiopathic osteoporosis aged 27-74 years (mean, 52.4 years) were randomized to receive either nasal SCT (200 IU) or a nasal placebo daily for a period of 1 year. All the men received a daily supplement of 0.5 g of calcium. The men who received SCT had a mean (+/-SEM) increase in BMD of 7.1 +/- 1.7% at the lumbar spine. In contrast, the men who received the placebo had an increase of 2.4 +/- 1.5% (p > 0.05) for the comparison with baseline. The increase in lumbar BMD in the calcitonin group was significantly greater than that in the placebo group (p < 0.05). There were no significant changes in the femoral neck, trochanter, or Ward's triangle relative to both baseline and placebo after 12 months. Treatment with nasal SCT resulted in a significantly pronounced suppression of bone resorption markers (urinary deoxypyridinoline [DPD], type I cross-linked N-telopeptide [NTX], and type I cross-linked C-telopeptide [CTX]) and to a lesser extent in bone formation markers (serum bone-specific alkaline phosphatase [BALP], osteocalcin [OC], serum C-terminal procollagen type I extension peptides [PICP], and serum N-termnal procollagen type I extension peptides [PINP]), whereas the placebo did not. Therapy was tolerated well and there were no treatment-related adverse events. We conclude that intranasal SCT (200 IU daily) is safe and effective in increasing lumbar BMD and reducing bone turnover in men with idiopathic osteoporosis.

Improving risk assessment: hip geometry, bone mineral distribution and bone strength in hip fracture cases and controls. The EPOS study. European Prospective Osteoporosis Study.

Hip geometry and bone mineral density (BMD) have previously been shown to relate independently to hip fracture risk. Our objective was to determine by how much hip geometric data improved the identification of hip fracture. Lunar pencil beam scans of the proximal femur were obtained. Geometric and densitometric values from 800 female controls aged 60 years or more (from population samples which were participants in the European Prospective Osteoporosis Study, EPOS) were compared with data from 68 female hip fracture patients aged over 60 years who were scanned within 4 weeks of a contralateral hip fracture. We used Lunar DPX 'beta' versions of hip strength analysis (HSA) and hip axis length (HAL) applied to DPX(L) data. Compressive stress (Cstress), calculated by the HSA software to occur as a result of a typical fall on the greater trochanter, HAL, body mass index (BMI: weight/(height)2) and age were considered alongside femoral neck BMD (FN-BMD, g/cm2) as potential predictors of fracture. Logistic regression was used to generate predictors of fracture initially from FN-BMD. Next age, Cstress (as the most discriminating HSA-derived parameter), HAL and BMI were added to the model as potentially independent predictors. It was not necessary to include both HAL and Cstress in the logistic models, so the entire data set was examined without excluding the subjects missing HAL measurements. Cstress combined with age and BMI provided significantly better prediction of fracture than FN-BMD used alone as is current practice, judged by comparing areas under receiver operating characteristic (ROC) curves (p<0.001, deLong's test). At a specificity of 80%, sensitivity in identification was improved from 66% to 81%. Identifying women at high risk of hip fracture is thus likely to be substantially enhanced by combining bone density with age, simple anthropometry and data on the structural geometry of the hip. HSA might prove to be a valuable enhancement of DXA densitometry in clinical practice and its use could justify a more proactive approach to identifying women at high risk of hip fracture in the community.

Influence of orthotopic placement on the incorporation and mechanical strength of a loaded structural cortical graft: an experimental study in rabbits.

The biological and mechanical behavior of loaded cortical autografts were evaluated in an experimental study using 40 adult male New Zealand rabbits divided into 4 groups. A double osteotomy was performed on all animals at the mid-diaphysis of the right ulna. The bone segment (5 mm) in between the osteotomies was considered a cortical autograft and fixed with an intramedullary Kirschner wire. The graft was fixed in an orthotopic manner in groups A and C, and rotated 180 degrees in groups B and D. After the animals were sacrificed (at 2 months for groups A and B and at 4 months for groups C and D), bone mineral density, graft cross-sectional geometry, and SSI index were assessed. Mechanical testing of the grafted area was carried out using a three-point bending configuration, and the parameter fracture load was assessed. Graft union and incorporation also was studied in histologic sections. In group C (orthotopic graft placement--4 months), bone specimens showed statistically significantly higher values for fracture load, total cross-sectional area, volumetric total bone mass and density, and polar SSI (P values < or = .05) compared to the other groups. In the same group, union and incorporation of the graft was complete, the cortex showed low porosity, and the collagen fibers were mature and properly oriented. Structural cortical bone autografts placed in an orthotopic manner recognize the new mechanical environment as optimal and thus their biological and mechanical behavior are enhanced. Loaded structural cortical grafts should be placed in an orthotopic manner when used for the management of cortical bone defects.

Hip geometry, bone mineral distribution, and bone strength in European men and women: the EPOS study.

Hip geometry and bone mineral density (BMD) have been shown previously to relate, independently of each other, to risk of hip fracture. We used Lunar DPX "beta" versions of hip strength analysis (HSA) and hip axis length (HAL) software to analyze scans from ten representative age-stratified population samples in the European Prospective Osteoporosis Study (EPOS). All 1617 subjects were >50 years of age, and 1033 were women. The data were modeled with gender and center as categorical variables. The bone mineral density of the upper half of the femoral neck declined at a faster rate with age than that in the lower half. Femoral neck cross-sectional moment of inertia (CSMI), a measure of resistance to bending, showed no significant age reduction in either gender. However, height and weight effects on CSMI were significantly more beneficial in men than in women (0.002 < p < 0.012) and the weight effect appeared to be mediated by bone mineral content (BMC). Compressive stress (Cstress), defined as the stress in the femoral neck at its weakest cross section arising from a standardized fall, was higher in women. Although Cstress increased with body weight when BMC was held constant, in practice it fell through the association and statistical interaction of rising body weight with rising BMC. HAL, as expected, was strongly positively associated with male gender and also height (p < 0.0001). Hip strength-related indices were markedly center-dependent. Significant differences (p < 0.0001) were noted between the centers for all the variables investigated that related to hip geometry. Adjustment for femoral neck bone mineral content (totBMC) showed these center differences to account for >50% of center variation in hip strength, which remained highly significant (p < 0.0001). We conclude that there are substantial geographical differences in femoral neck geometry as well as in BMD. These geometric variations may contribute to the large variations in hip fracture risk across Europe. The effects of aging on hip strength need to be explored in longitudinal studies.

Influence of weight gain on spine mineral density in postmenopausal women.

We studied the relationships between weight variables and spine bone mineral density (BMD) in 183 postmenopausal women aged 34-76 years. There was a significant positive correlation of current body mass index (cBMI) and % of ideal body weight (IBW) with BMD. Moreover, the increase in BMI and % IBW was also positively and significantly associated with a higher age-adjusted lumbar BMD. Weight gain, estimated as the difference between current body weight and past "ideal" body weight, was associated with significant age-adjusted BMD with a threshold of 17%, and postmenopausal women with a gain of over 17% had significantly higher spine BMD.

Mechanical stimulation in the form of vibration prevents postmenopausal bone loss in ovariectomized rats.

Physical exercise is recommended for the prevention and treatment of osteoporosis. However, its exact role and effectiveness in adulthood is unclear. While vigorous exercise of long duration enhances bone density, few adult individuals comply with such training programs. The present study evaluates the influence of nonphysiological mechanical stimulation, in the form of low intensity vibration (frequency: 50 Hz, acceleration: 2 g, 30 min/day for 5 days/week), on the prevention of bone loss in an animal model of postmenopausal osteoporosis. In the ovariectomised groups of rats a statistically significant (p < 0.05) decrease of bone density (femur and tibia) was recorded at 5 weeks postovariectomy. This effect was maintained for the 12 week duration of the study. Vibration prevented early bone loss after ovariectomy. Vibrated ovariectomised rats showed statistically significantly higher (p < 0.05) BMD values compared to those of their ovariectomised controls at 5 weeks. Vibration did not influence the bone density of the SHAM-operated rats. Although vibration increased ultimate strength (fracture load of the rat femur) in the ovariectomised rats, this finding was not statistically significant. Our data indicate that this method of safe and easily applicable vibration, in the form of a vibrating platform, is effective in preventing early postovariectomy bone loss in an animal model.

Quantification of image persistence in a digital angiography system.

Image persistence, as a characteristic of video imaging systems affecting the quality of fast moving fluoroscopic images, is shown to vary considerably. A simple quantitative method for measuring image persistence in a digital angiography system is presented, together with a series of image intensifier exposure-response curves. For the Saticon tube, used with the Siemens 3VA Digitron, it was found that persistence increased for low exposure rates and may increase to 31% at a 120 ms interval. In addition, a sharp increase in image persistence, from 8.3% to 33%, was observed within 18 months from installation of the system.