Bone mineral density and bone scintigraphy in children and adolescents with osteomalacia

In order to demonstrate the role of bone mineral density (BMD) measurement and bone scans in the management of patients with osteomalacia, radioisotope bone scintigraphy using technetium-99m methylene diphosphonate (MDP) and BMD measurements of the lumbar spine and femur by means of dual X-ray absorptiometry (DXA) were performed at the time of diagnosis and 6 months after therapy in 26 Saudi patients (17 females and nine males). Their mean age was 13.5 years (range, 5–16). BMD measurements were compared with those of normal Saudi subjects matched for age and sex. Bone scan showed an increase in tracer uptake throughout the skeleton (“superscan”) in all children and demonstrated multiple stress fractures in eight. The mean BMD for the lumbar spine was 0.53 g/cm² (Z-score, −3.1) and for the femoral neck 0.55 g/cm² (Z-score, −2.8). Repeated bone scan and BMD after 5 months of therapy with oral vitamin D, calcium and proper sun exposure demonstrated a significant increase (P<0.001) in BMD and healing of pseudofractures. In conclusion, as a non-invasive method with minimal radiation exposure, measurements of BMD in children with osteomalacia are to be recommended in the initial assessment of the severity of osteopenia and in the follow-up to monitor the response to therapy. Bone scintigraphy is valuable in demonstrating the site and severity of stress fractures.     

Comparison between femoral bone mineral parameters assessed by QCT and dual X-ray densitometry

The aim of this study was to assess the agreement between different femoral bone mineral measures and their agreement with some biomechanical parameters. By means of quantitative CT (QCT) and dual X-ray absorptiometry (DXA), measurements were made in different locations of 33 pairs of human femur specimens. There was a principal distinction between bone density as measured by QCT and bone mass as measured by QCT and DXA. Bone mass measured by QCT and the bone mineral content (BMC) measured by DXA are true mass parameters. However, bone mineral density (BMD) as measured by DXA agreed substantially better with the mass measures than with the densities. The mass measures, including the BMD, had good agreements with each other, with a common reference parameter and with the biomechanical parameters. The QCT densities had, on the average, poor agreements with each other, with the other bone mineral measures (including the MBDs), and with the mechanical parameters. The gender differences were less for the QCT densities than for the mass parameters, whereas in this regard the BMDs were intermediate. All measures had approximately similar reproducibilities. Although all mass measures, including the BMDs, seemed to agree with a general structural property of the femur, the bone densities seemed to have local variations, probably to adapt the calcium distribution and bone geometry to local biomechanical requirements. We suggest that BMD should be denoted mass per projected area to avoid any misconceptions concerning the nature of this parameter. Correspondence to: A. Høiseth     

CT evaluation of trabecular and cortical bone mineral density of the lumbar spine in patients on hemodialysis

It is difficult to evaluate the severity of bone involvement in patients on maintenance hemodialysis (HD) by the measurement of vertebral bone mineral density (BMD), since many endocrine factors influence bone metabolism, making the value of BMD variable from high to low. It is also difficult to interpret the BMD measured in one ROI (region of interest) since bone density distribution is sometimes very heterogenous. On the other hand QCT method is useful to evaluate the value of trabecular and cortical bone mineral density separately. Vertebral BMD was measured in 138 patients on maintenance HD, by using DEQCT (dual energy QCT). 161 patients without bone metabolic disorders were studied for control group. In patients on HD, various BMD values ranging from high to low were observed, and there was no correlation between BMD value and duration of HD. The number of patients with low mineral content was greater than that with high mineral content in both cortical and trabecular bone. The trabecular BMD decreased with age, and the speed of BMD decline was the same in both sexes. The rapid decrease of trabecular BMD after menopause seen in control female group was not observed in female patients on hemodialysis. The deviation of BMD from the age-matched average BMD value was smaller in older male patients than that in young male and female patients. In order to evaluate the difference of change between the trabecular and cortical bone at the same vertebra, cases in which discrepancy of Z-score was more than 0.2 were divided into three groups; group A: increased trabecular BMD (Z-score greater than 1), group B: decreased trabecular BMD (-1 greater than Z-score), group C: normal trabecular BMD (-1 less than Z-score less than 1), and in each group T/C ratio (Z-score of trabecular BMD/Z-score of cortical BMD ratio) was evaluated. In group A, almost all cases showed trabecular BMD to be higher than cortical, and in group B, 60% cases showed trabecular BMD to be lower than cortical, suggesting that the change of BMD in trabecular bone is greater than that in cortical bone.     

Anteroposterior versus lateral bone mineral density of spine assessed by dual X-ray absorptiometry

Recently, it has been suggested that lateral (LAT) spine bone mass measurements by absorptiometry may be more sensitive for detecting bone loss than the standard anteroposterior (AP) projection. The aim of this study was to evaluate the precision of LAT spine dual-energy X-ray absorptiometry (DEXA) and its diagnostic sensitivity. A group of 1554 subjects with no risk factors that might affect bone metabolism and 185 osteoporotic patients with vertebral fractures were studied. Bone mineral density (BMD) was measured in the lumbar spine (standard AP and LAT projections) and proximal femur with a DEXA absorptiometer. The precision of the measurements was assessed in 15 volunteers. Diagnostic sensitivity was evaluated by the Z-score method. Comparing young people and the elderly, spine bone loss in the latter was similar for AP and LAT projections, when it was evaluated in absolute values (glcm²). However, when it was evaluated in percentage terms, bone loss was about twice as high in the LAT projection. LAT spine BMD correlated significantly with all the other areas assessed. The best correlation was found with the standard AP projection (r=0.67,P<0.0001). The precision in the LAT projection was found to be within an acceptable range (1.6% in normal subjects, 2% in osteoporotic patients), even though it was about twice that obtained in the AP projection. Diagnostic sensitivity was also better with the AP projection. It is concluded that LAT spine BMD measurements can be assessed with acceptable precision although it is about twice as high as for AP spine measurements. The percentage decrease in BMD in the elderly is greater for measurements made in the LAT projection than for measurements made in the AP projection. However, there is no enhancement of diagnostic sensitivity in osteoporosis. BMD measurements in the LAT projection are not as good as in the AP projection but they may offer complementary information of the regional evolution of spine bone mass.     

Current and innovative methods for noninvasive bone densitometry

This article summarizes a variety of noninvasive techniques for measuring bone density in the clinical setting. Although dual-energy x-ray absorptiometry and quantitative computed tomography are currently the most widely used methods, older techniques such as radiogrammetry and single-photon absorptiometry continue to have research applications, and experimental approaches such as compton scattering and proton activation analysis may be important in the future. The evaluation of bone mass measurement underscores continuing progress in our understanding of bone metabolism and biomechanics, and has provided valuable insight into improvements in the therapy of osteoporosis and other forms of metabolic bone disease.     

Evaluation by EMI CT 5005 Scanner of bone mineral contents variations. A proposed skeletal index for clinical use (author's transl)

Two groups of subjects, ranging from 20 to 40 years of age the first and from 65 to 85 years the second, have been submitted to bone density measurements by EMI CT 5005 All-Purpose Scanner (140 kV; 28 mAs) and the average values compared. The difference between the average values of the two groups has been taken as a scale of points to evaluate the mineral contents of bone. By the group of older subjects the loss in trabecular bone (lumbar spine L2/L3) proved to be 59.51 EMI units, corresponding to the 47.6% of the mineral contents (p = < 0.01); the loss in compact bone (femur) was 6.6 EMI units corresponding to 5.28% of the mineral contents (p = < 5). The trabecular bone and compact bone average values added together give a whole-skeleton mineral contents index. This index applied to the group of older subjects showed a diminution of 65.81 EMI units indicating a 52.6% loss of mineral contents. Repeated measurements taken at a distance of time proved the method to be fairly reliable with acceptable degree of accuracy (+/- 5%). A tentative approach to clinical use of the skeletal index gave satisfying results.     

Comparisons of bone mass measurements on various skeletal sites including quantitative ultrasonography of the calcaneus for assessing age-related losses, their correlations, and diagnostic agreement using the Japanese and WHO criteria for osteoporosis

Purpose The aim of this study was to compare age-related bone losses and correlations among several bone mass measurements and to evaluate diagnostic agreement among them using the Japanese and WHO criteria for osteoporosis. Materials and methods A total of 846 women (mean ± SD: age 54 ± 9 years) were evaluated. Bone mineral densities of the lumbar spine, femoral neck, and calcaneus were measured by dual X-ray absorptiometry and distal radius by peripheral computed tomography. Quantitative ultrasonography (QUS) parameters of the calcaneus were also measured. The age-related bone losses after 50 years of age and correlations among bone mass results were evaluated using linear regression analysis. Diagnostic agreement was evaluated by kappa statistics. Results The annual losses ranged from 1.0% to 1.6%. The correlation coefficients ranged from 0.54 to 0.78. The kappa scores ranged from 0.52 to 0.30 for all subjects using the Japanese criteria and from 0.38 to 0.15 using the WHO criteria. Conclusion Bone mass measurements including QUS on various skeletal sites documented age-related changes similarly, and their bone masses correlated moderately. The diagnostic agreements among them were fair to poor. To screen out women with a risk of osteoporosis, it is important to choose which technique to use and which skeletal site to measure.     

Assessment of bone mineral content and bone mass by non-invasive radiologic methods

Methods for quantitative determination of bone mineral and bone mass in normal subjects and in patients with metabolic bone disorders can be measured by the Compton scattering technique, the neutron activation analysis, by measurement of metacarpal bone mass, by single and dual photon absorptiometry, and by quantitative computed tomography. Measurement on metacarpal bone (radiogrammetry) seems to be able to distinguish between resorption and/or new bone formation at the periosteal and/or endosteal surface. The intraindividual observer variation on combined cortical thickness (D-d), cortical area (D2-d2), metacarpal bone mass (D2-d2)/D2-varies from 0.7 to 2.5 per cent and the interindividual observer variation from 1.0 to 5.8 per cent. Single photon absorptiometry measures bone mineral content in the forearm with great precision. The reproducibility using repeated measurements and automatic selection of the measuring area is about one per cent and can be used to follow changes in mineral content with time in patients with metabolic bone diseases. The dual photon absorptiometry may be used for measurements of bone mineral content in lumbar spine, in the femoral neck and measurement of total body calcium with an accuracy of less than 6 per cent and a precision below 3 per cent. Quantitative computed tomography has the ability to measure trabecular and cortical bone both centrally and peripherally. Using CT scanning, scanner related changes with time (day-to-day variation +/- 4%), patient repositioning (less than 1.5%), and fat concentration (residual uncertainty of approximately 1/6 of the biologic variation) are important factors influencing the accuracy and reproducibility of the values of the measured bone mineral content.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparisons between X-ray photodensitometric and gamma-ray absorptiometric findings of bone mineral measurements, and the evidence of their convertibility.

Fifty-two bone mineral measurements were made in chronic renal failure patients using two different radiologic techniques concurrently: gamma-ray absorptiometry; and x-ray photodensitometry. Although the sites of measurements of the cortical bone mineral mass in radius were different (distal vs. proximal) and different parameters were determined (in units of gm/cm vs. gm/cm2), a moderately good correlation was found between measurements by the two techniques (r = 0.61, p less than 0.001). Using external bone width, it was possible to calculate from photodensitometric measurements the bone mass per unit length (gm/cm). This conversion improved the correlation with absorptiometry values considerably (r = 0.78, p less than 0.001). A similar correlation was found between the trabecular bone mass in the distal radius, measured by absorptiometry, and the cortical bone mass in the proximal radius, determined by photodensitometry (r = 0.79, p less than 0.001), the correlation between the cortical and trabecular bone masses by absorptiometry being only slightly higher (r = 0.84, p less than 0.001). The residual variations not explained by the correlations between the absorptiometric and photodensitometric techniques may be largely due to the real differences of bone mineral masses at the two measuring sites and by the inherent methodological errors.     

Bone mineral assessment: new dual-energy CT approach

Most clinical quantitative computed tomographic (CT) determinations of bone mineral content are hampered by inability to properly account for the various substances contained within the spongiosa (spongy bone). In general, the presence of adipose tissue lowers the CT numbers (Hounsfield units) and leads to underestimation of bone mineral content. Collagen matrix has the opposite effect. A new approach to obtaining data from postreconstruction dual-energy CT scans accounts for five principal constituents of the spongiosa. In addition to bone mineral values, the method also provides the adipose tissue concentration, calcium content, and density of the total trabecular space. Since calcium values are provided, the measurements can be compared with prereconstruction dual-energy data that are acquired simultaneously. A new solid-plastic calibration phantom was utilized in this study, and data were obtained from 26 subjects. Dual-energy data were correlated with single-energy measurements (r greater than .96), and calcium measurements were correlated with the bone mineral determinations (r = .97) in these 26 cases. All measurements of the various vertebral constituents agreed with published values.     

Quantitative bone scintigraphy using SPECT

A quantitative single photon emission computed tomography (SPECT) technique for measuring radiopharmaceutical uptake in humans has been applied to bone scintigraphy. The method was validated by comparing SPECT measured percent of injected [99mTc]MDP in 16 normal skulls with well counter measurements of samples of the same bones obtained at surgery. A very good correlation (r = 0.96) was found. A very good interobserver correlation (r = 0.99) and agreement were also obtained when using quantitative bone scintigraphy (QBS). Control SPECT studies of uptake in the right and left iliac bones and the right and left sacroiliac regions in each patient showed no significant differences between the contralateral sides. Studies done in seven subjects at 2 and 4 hr after the same injection and in nine subjects 4 to 8 mo later in the same subjects showed a very good agreement and no significant differences between the two measurements were found. QBS is suggested as an accurate and reproducible index for assessment of the mass of remodeling bone. Preliminary results showed differences in QBS of normal subjects at different ages. A group of 68 young patients aged 18-26 yr showed a significant higher QBS (p less than 0.001) when compared to an older group of 62 patients aged 50-85 yr. There was, however, a wide range of uptake values for the same bone in the same group, suggesting that the method should best be used for following individual patients over time.     

Methodologies for the measurement of bone density and their precision and accuracy

Radiographic methods of determining bone density have been available for many years, but recently most of the efforts in this field have focused on the development of instruments which would accurately and automatically measure bone density by absorption, or by the use of x-ray computed tomography (CT). Single energy absorptiometers using I-125 have been available for some years, and have been used primarily for measurements on the radius, although recently equipment for measuring the os calcis has become available. Accuracy of single energy measurements is about 3% to 5%; precision, which has been poor because of the difficulty of exact repositioning, has recently been improved by automatic methods so that it now approaches 1% or better. Dual energy sources offer the advantages of greater accuracy and the ability to measure the spine and other large bones. A number of dual energy scanners are now on the market, mostly using gadolinium-153 as a source. Dual energy scanning is capable of an accuracy of a few percent, but the precision when scanning patients can vary widely, due to the difficulty of comparing exactly the same areas; 2 to 4% would appear to be typical. Quantitative computed tomography (QCT) can be used to directly measure the trabecular bone within the vertebral body. The accuracy of single-energy QCT is affected by the amount of marrow fat present, which can lead to underestimations of 10% or more. An increase in marrow fat would cause an apparent decrease in bone mineral. However, the precision can be quite good, 1% or 2% on phantoms, and nearly as good on patients when four vertebrae are averaged. Dual energy scanning can correct for the presence of fat, but is less precise, and not available on all CT units. QCT of the femoral neck has recently been attempted, but presents difficulties that make it unlikely to become widely accepted. Recently there has been much interest in using gamma cameras for dual energy bone density measurements. Although this can present some difficulties, several groups reportedly have overcome them, and this technique may have more widespread application in the future.     

A region-of-interest template for three-dimensional stereotactic surface projection images: initial application to the analysis of Alzheimer's disease and mild cognitive impairment

OBJECTIVE: To construct a region-of-interest (ROI) template for Z-score images of three-dimensional stereotactic surface projections (3-D SSP) and to assess whether the ROI template can be a useful tool for evaluation of brain perfusion abnormalities of neurological disorders. MATERIALS AND METHODS: We constructed the ROI template for Z-score images of 3-D SSP based on the standardized magnetic resonance imaging data of 10 healthy volunteers. We assigned a total of 26 ROIs to Z-score images and superimposed it on Z-score images constructed from the brain perfusion SPECT data of 15 patients with Alzheimer's disease and 10 patients with mild cognitive impairment (MCI) who developed Alzheimer's disease within the following 2 years. We then obtained the mean Z-scores of each ROI and examined them to determine whether the hypoperfusion typical of Alzheimer's disease had been demonstrated quantitatively. We also visually inspected the Z-score image of each patient in both groups to determine whether the areas with the highest Z-scores were demonstrated within the ROIs of regions typical of Alzheimer's disease. RESULTS: In the patients with Alzheimer's disease, our ROI template quantitatively demonstrated hypoperfusion in regions typical of the disease and the Z-scores were very high. In the MCI patients, the mean Z-scores of the ROI in the posterior cingulated gyrus were the highest among all regions. Visual inspection of the Z-score images of each patient in both groups confirmed that the areas with the highest Z-scores were demonstrated within the ROIs in regions typical of Alzheimer's disease in all cases. CONCLUSION: Use of 3-D SSP methods and our ROI template enables automated quantitative evaluation of brain function images over the entire brain surface. In addition, the ROI template may facilitate visual interpretation of functional images of individual patients with neurological disorders.     

Normalized BMD as a predictor of bone strength

RATIONALE AND OBJECTIVES: In the noninvasive evaluation of bone quality, bone mineral density (BMD) has been shown to be the single most important predictor of bone strength and osteoporosis-related fracture. Among the methods of measuring BMD, dual x-ray absorptiometry (DXA) has widespread acceptance due to its low radiation, low cost, and high precision. However, DXA measures area BMD instead of true volumetric density; thus, a larger bone will tend to have a high BMD than will a smaller bone. Therefore, the comparison of BMDs of bones of different sizes can be misleading. In this study, the authors tried to compensate for the size effect by normalizing the area BMD with bone size as measured from a standard pelvic radiograph. MATERIALS AND METHODS: The overall method for calculation of normalized BMD included conventional area-based BMD from DXA and the extraction of geometric measures from pelvic radiographs. The database for analysis included 34 femoral neck specimens. Regression analysis was performed between the normalized volumetric BMD, measured from femoral neck region, and the mechanical properties obtained from trabecular bone cubes machined from the same region. RESULTS: After normalization of the area BMD, the coefficient of determination increased from 0.30 to 0.43 for the Young modulus and from 0.27 to 0.37 for bone compressive strength. CONCLUSION: A noninvasive method of normalizing BMD can improve the prediction of bone mechanical properties and has potential in monitoring changes in growing skeletons and in the clinical evaluation of bone quality.     

Assessment of bone mineral. Part 2

A number of different techniques are available to study bone mineral. Those based on radiographs are helpful as an initial approach to the symptomatic patient with advanced disease, but they do not have the sensitivity to detect early bone loss, to assist in the estimation of fracture risk, or to monitor effects of treatment in controlled drug studies. A radiograph of the spine and hip, however, should be the first step before other tests are ordered. Photon absorptiometry methods or CT-based tests are currently most attractive as second-line approaches. Of these, photon absorptiometry is more widely tested clinically and allows studies of predominantly cortical or trabecular bone sites and total skeletal calcium. Although all of this cannot be done reliably with one instrument under routine laboratory conditions at present, it may well become possible in the near future. Of the CT-based procedures, the forearm scanner is very attractive because of its high precision and accuracy and the fact that it allows measurement of trabecular bone only. The technique is restricted to the forearm and may not be versatile enough for modern clinical requirements. A similar comment may be applicable to neutron-activation techniques of the hand, forearm, or spine. Low-level counting and the handling of neutron sources are not widely known techniques in many laboratories, and this will restrict their use in clinical practice. At this time there is no optimal technique available for mass screening for early osteoporosis. Dual-photon absorptiometry of the spine has been in use in our institution as the method of choice in selected patients for early detection of osteoporosis. However, for screening purposes the radius is still a very attractive bone to measure. At the currently used measuring sites, however, it does not have the sensitivity required to indicate spinal bone loss. Perhaps measurements closer to the distal end, where the trabecular-to-cortical bone ratios approach that in the spine, could be more sensitive. The difficulty of relocating the arm for photon absorptiometry can perhaps be solved for photon absorptiometry, or may be resolved by CT of the forearm. Correlation of the extreme distal radius with the spine is necessary to answer this question.     

Quantitative measurements of bone remodeling using 99mTc-methylene diphosphonate bone scans and blood sampling.

Quantitative studies of bone using (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) have a potentially valuable role in investigating the treatment of patients with metabolic bone disease. In this study we compared 3 different methods of measuring whole-skeleton (99m)Tc-MDP plasma clearance (K(bone)) in 12 osteoporotic postmenopausal women (mean age, 67.3 y) before participation in a clinical trial of an osteoporosis therapy. The aim was to compare the consistency and accuracy of the 3 methods before their use in evaluating the subjects' response to treatment. METHODS: Subjects were injected with 600 MBq (99m)Tc-MDP and 3 MBq (51)Cr-ethylenediaminetetraacetic acid ((51)Cr-EDTA) and whole-body bone scan images were acquired at 10 min, 1, 2, 3, and 4 h. Two-minute static images of the thighs were acquired immediately after the 1- to 4-h whole-body scans. Six blood samples were taken between 5 min and 4 h, and free (99m)Tc-MDP was measured using ultrafiltration. The glomerular filtration rate (GFR) was estimated from the (51)Cr-EDTA plasma curve. The methods used to evaluate K(bone) were (a) the area-under-the-curve (AUC) method, in which the GFR measurement was subtracted from the total (bone plus renal) clearance (K(total)) measured from the free (99m)Tc-MDP plasma curve; (b) the modified Brenner method, in which (99m)Tc-MDP renal clearance estimated from the whole-body counts was subtracted from the total clearance measured from the rate of elimination of tracer from soft tissue; and (c) the Patlak plot method, which was also used to derive regional values of K(bone) for the skull, spine, pelvis, arms, and legs. RESULTS: There was good agreement between the 3 methods of measuring K(bone). (mean K(bone) +/- SD: AUC method, 30.3 +/- 6.4 mL x min(-1); Brenner method, 31.1 +/- 5.8 mL x min(-1); Patlak method, 35.7 +/- 5.8 mL x min(-1)). The correlation coefficients between the methods varied from r = 0.767 (P = 0.004) to r = 0.805 (P = 0.002). Regional measurements of (99m)Tc-MDP clearance gave the following percentages of the whole-skeleton clearance: skull, 13.3%; spine, 16.6%; pelvis, 17.2%; arms, 11.1%; legs, 23.7%. CONCLUSION: The 3 methods gave consistent and accurate measurements of K(bone). The Patlak method can be used to study regional as well as total-skeleton values of K(bone).     

The long-term performance of DXA bone densitometers

Long-term performance of a bone mass measuring device is an important criterion when considering the purchase of such equipment and has been regarded as an important feature of dual X-ray absorptiometry (DXA). The performance of a 6-year-old bone densitometer, the Lunar DPX alpha, which has undertaken 1500 scans annually over this period, was assessed. The short-term coefficient of variation calculated from 15 measurements with repositioning on a single day, using the Lunar aluminium phantom, was 0.242%. Long-term precision, also calculated by the coefficient of variation, was 0.548%. The manufacturer's quality control (QC) procedure was performed daily and allowed the machine to be used except on 15 occasions when bone density measurements could be acquired after rebooting. However, a 2.2% shift in phantom values occurred in July 1996 owing to a photomultiplier tube failure, but this did not produce a failure in the Lunar QC. The optical disc drive was replaced in July 1997. The machine failed to back up on six occasions over the last 2 years owing to software corruption and the acquired femur data were not saved on seven occasions owing to overloading of the memory buffer. In conclusion, expected hardware failure and minor software problems have occurred. We were concerned that the manufacturer's QC failed to detect a 2% shift in the phantom bone mineral density values and recommend regular measurements of the Lunar aluminum phantom in addition to the daily QC measurement of the tissue-equivalent block. We were nevertheless impressed by the long-term stability and reproducibility of the Lunar DPX alpha.     

Effect of active metabolites of vitamin D 3 on the status of rat bone tissue in various experimental models of hypokinesia

Rats were for 6 weeks either kept in small cages or suspended. The caged rats showed hypocalcemia and lowered active transport of calcium in the intestine and no changes of PTH in blood. Femoral bone measurements in these rats revealed reduced density and content of calcium and phosphorus in proximal epiphyses, slight increase of these parameters in diaphyses and lack of changes in distal epiphyses. The suspended rats exhibited normocalcemia, noticeable but insignificant increase of PTH and calcium absorption as well as decreased density and content of calcium and phosphorus in distal epiphyses and their slight increase in diaphyses. Administration of active vitamin D3 metabolites led to an increase of bone mineral density and content only in those femur compartments where hypokinesia-induced changes were seen. It is concluded that during hypokinesia bone disorders are predominantly produced by local factors that may increase bone sensitivity to systemic influences.     

Effect of impact load and active load on bone metabolism and body composition of adolescent athletes

PURPOSE: It is unclear whether adolescents involved in nonweight-bearing activities experience a delay in bone growth acquisition and sexual maturation. The purpose of this study was to compare bone mineral density (BMD), body composition, hormonal profile, and bone biochemical markers of adolescent athletes active in sports involved in impact load sports with those participating in active load sports. METHODS: Forty-five male Caucasian athletes aged 12--18 yr were divided into two groups according to type of skeleton loading, impact (N = 18), or active (N = 27). Twenty-four male Caucasian adolescents (12--18 yr) served as controls and only performed the activities included in their physical education classes. All subjects were assessed for bone mass, body composition, and bone age by dual x-ray absorptiometry (DXA). Serum calcium (Ca), phosphorus (P), bone-specific alkaline phosphatase (BAP), total testosterone, FSH, LH, urinary calcium to creatinine ratio (Ca/Cr), and urinary deoxypyridinoline crosslinks to creatinine ratio (DPD/Cr) were measured. RESULTS: The impact load group presented the highest BMD among the three groups for all studied sites. Lean mass and absolute weight were correlated with all of the bone mass measurements. BAP levels were significantly higher and testosterone levels significantly lower in the active load group compared with the impact group. CONCLUSION: High-impact load exercises have a beneficial effect on bone mass in male adolescents. There is also a positive correlation of weight and body composition with BMD. However, further longitudinal studies are necessary to determine whether there is a delay in bone growth acquisition among adolescents involved in a nonweight-bearing exercise regimen and its association with sex hormones.     

Physical activity levels are associated with regional bone mineral density in boys

ABSTRACT

Background: Youth is a crucial period for bone gain, and physical activity (PA) has shown to increase bone mineral density (BMD) in this period. However, whether PA affects regional BMD is unclear. Thus, the aim of this study was to analyze the relationship between PA levels and regional BMD in youths. Methods: The sample included 110 children and adolescents aged 6–14 years. Body mass, height, sitting trunk length, and leg length were obtained for body mass index and maturity offset calculation. The arms, pelvis, spine, trunk, and legs BMD were measured by double energy X-ray absorptiometry. The PA was evaluated by questionnaire, and youths were classified as low, moderately, or highly physically active.

Results: The sample included 63.7% boys and 36.3% girls with mean age of sample 9.5 (±1.6) yrs. Age, body mass index, and maturity offset were similar between sexes (p > 0.05). Boys with low PA levels had lower BMD Z-score for arms (?0.20 ± 0.71 vs. 0.30 ± 1.19, p = 0.006) and legs (?0.14 ± 1.00 vs. 0.35 ± 1.06, p = 0.026) compared to highly physically active youths. Multiple linear regression showed a positive linear relationship between legs BMD and PA in boys (β = 0.72 [95% CI = 0.09; 1.36]).

Conclusion: In boys, low PA levels are associated with lower BMD in arms and legs.