Measurement of bone in the os calcis: a clinical evaluation.

Bone mineral content (BMC) was measured in the os calcis of 232 normal subjects aged 17-82 years. The mean reproducibility (coefficient of variation) of the measurement was 1.8%. Substantial bone loss occurred between the ages of 20 and 50 years, and in females the menopause was associated with additional bone loss. There was no significant difference in the rate of bone loss in females and males, but the mean BMC was greater at all ages in males than in females. We also compared os calcis BMC with spinal bone mineral density (BMD), measured by quantitative computed tomographic (CT) scanning, in 85 subjects: 33 were normal controls, 19 had osteoporosis defined by the presence of one or more pathological fractures, and in the remainder the CT examination was performed at the patient's request. Os calcis BMC correlated with spinal BMD in both females (r = 0.69, p less than 0.001) and males (r = 0.84, p less than 0.001). However, the os calcis BMC did not reliably predict spine values around the CT "fracture threshold" of 90-100 mg/cm3 and did not correlate with osteoporotic fracture as well as did spinal BMD. It is concluded that measurement of the os calcis BMC is of limited clinical usefulness for the early diagnosis of osteoporosis.

A comparison of single and multi-site BMC measurements for assessment of spine fracture probability.

In a prospective study of 699 women, 39 new spine fracture cases were observed during a mean follow-up of 3.6 yr. Spine fracture incidence was compared to initial bone mineral content (BMC) of the calcaneus, distal radius, proximal radius, and the lumbar spine. BMC at all four sites was significantly related to spine fracture incidence. Women at -1 s.d. for calcaneal BMC had a sevenfold greater probability of spine fracture than women at +1 s.d.; women at -2 s.d. had a 50-fold greater probability than women at +2 s.d., even after adjustment for the effects of age. Combinations of BMC at two sites further strengthened the relationship to spine fracture; the best two-site combination is calcaneus and distal radius BMC. Thus women can be categorized and stratified according to future fracture risk, and the selection of postmenopausal women for preventive treatments can be guided by measurements of BMC.

Photon scattering measurement of calcaneal bone density: result of in vivo cross-sectional studies.

The density of trabecular bone in the os calcis has been measured in 321 subjects using a gamma ray scattering technique. In normal subjects it was shown that density could be predicted from body weight and age with a standard error of 5.6%. It was also shown that the dependence of density upon weight and age was the same for both sexes. When the os calcis had been subjected to a greater than normal mechanical stress by either increased physical activity or excessive body weight, trabecular bone density was increased. Density was measured in 128 patients in whom the incidence of skeletal demineralization was expected to be greater than that in control subjects. Some significant reductions in density were observed. It is projected that density measurements might be of value in those situations where, in response to metabolic stress, the rate of loss of mineral from trabecular bone is greater than that from cortical bone.

Quantitative assessment of bone mineral by photon scattering: calibration considerations.

The ratio of the coherent-to-Compton photons scattered from bone can be used to measure its mineral density. Conversion of this ratio (R) to bone mineral density (BMD) requires calibration using bone simulating phantoms. The widely used aqueous solution of K2HPO4 proved unsatisfactory for calibration purposes when using the coherent-to-Compton technique. These solutions differ markedly in their scatter spectra and composition from trabecular bone. In this study a new and more realistic series of phantoms is proposed which simulates well the trabecular bone of the calcaneum. These phantoms are made of bone ash suspended in white petrolatum in varying concentrations. A calibration curve has been established using these phantoms with a range of BMD values of 0 to 347 mg/cm3. The scatter spectra, and range of R values and BMD of these phantoms are in very good agreement with those of real trabecular bone. A measuring device has been built for the determination of the BMD of the calcaneum by using the established calibration curve.

In vivo measurements of bone lead--a comparison of two x-ray fluorescence techniques used at three different bone sites.

In vivo bone lead measurements have been made on a group of about 120 people, most of whom were lead exposed workers. Two different x-ray fluorescence (XRF) techniques were used to make measurements at three bone sites. Finger lead was measured using 57Co sources, and lead measurements were made in both tibia and calcaneus with a technique based on 109Cd sources. The results of the bone lead measurements correlated strongly with each other and with the index of cumulative exposure, thus confirming the value and reliability of these in vivo measurements as a tool in the study of chronic lead exposure. Measurement precision, +/- 1 standard deviation, was highest for tibia +/- 7.4 micrograms (g bone mineral)-1, +/- 16.6 micrograms (g bone mineral)-1 for the calcaneus and lowest for phalangeal lead +/- 25.0 micrograms (g bone mineral)-1. Maximum absorbed doses to the skin were comparable for all three measurements (1-3 mGy). The mean whole body dose equivalents were all low, but that for the finger measurement, 0.1 microSv, was significantly less than for the calcaneus and tibia measurements 3-5 microSv.

Coherent scattering and the assessment of mineral concentration in trabecular bone.

The number of 103.2 keV (153Sm) gamma-rays scattered coherently and incoherently from the os calcis of three cadaver feet has been measured using a high purity Ge detector. The ratio of the intensities of coherent to incoherent scattered photons is dependent on elemental composition while the number scattered incoherently is dependent on density. The results indicate that techniques for the assessment of mineral status in the skeleton may be based on either of these measurements and each will exhibit a similar sensitivity to a given biological change. It is shown that a method based entirely on the detection of coherently scattered photons will be more sensitive to changes in mineral composition than either of the above. Such a system is proposed and optimised with respect to incident beam energy and scattering angle. For a dose of 4 mSV, coherent intensity measurements with a precision of 3% are anticipated.

[Mineral content of the peripheral skeleton in patients with diabetes mellitus ]. / Ergebnisse der Bestimmung des Mineralsalzgehaltes am peripheren Skelett bei Patienten mit Diabetes mellitus.

In order to determine the effect of diabetes mellitus on bone mineral content, measurements with the iodine 125 isotope method of Cameron were carried out in the distal ulna and calcaneus of 40 patients. 38% of female and 20% of male diabetic patients showed abnormally low values. The most severe changes were found in patients with complications of diabetes. There was a correlation between the duration of the diabetes and the severity of the mineral loss.

[Experimental studies on the accuracy of mineral content assessment in spongiosa bone using quantitative CT (single energy measurement)]. / Experimentelle Untersuchungen zur Genauigkeit der Mineralsalzgehaltsbestimmung spongiöser Knochen mit Hilfe der quantitativen CT (Einenergiemessung).

The mineral content of 42 lumbar vertebral bodies (using a phantom to simulate living conditions) and of 30 calcanea was measured by quantitative CT. The bones were subsequently ashed and the calcium and fat content determined chemically. The mineral concentration (calibrated against a K2HPO4 solution) showed good correlation with the calcium content (for the lumbar vertebrae, r = 0.963 and for the calcanea r = 0.94. The fat content of the bone marrow leads to a systematic under-estimation of the mineral content, if one uses single energy CT measurements. The experimental findings can be satisfactorily treated in a quantitative way with the help of a model which contains the three components of spongy bone (mineral, fat and fat-free connective tissue.

A total dietary program emphasizing magnesium instead of calcium. Effect on the mineral density of calcaneous bone in postmenopausal women on hormonal therapy.

The use of calcium supplementation for the management of primary postmenopausal osteoporosis (PPMO) has increased significantly in the past few years. A review of the published data does not support calcium megadosing during postmenopause. Controlled studies showed no significant effect of calcium intake on mineral density of trabecular bone and a slight effect on cortical bone. Since PPMO is predominantly due to demineralization of trabecular bone, there is no justification for calcium megadosing in postmenopausal women. Soft tissue calcification is a serious risk factor during calcium megadosing under certain conditions. A total dietary program emphasizing magnesium instead of calcium for the management of PPMO takes into account the available data on the effects of magnesium, life-style and dietary habits on bone integrity and PPMO. When this dietary program was tested on 19 postmenopausal women on hormonal replacement therapy who were compared to 7 control postmenopausal women, a significant increase in mineral bone density of the calcaneous bone (BMD) was observed within one year. Fifteen of the 19 women had had BMD below the spine fracture threshold before treatment; within one year, only 7 of them still had BMD values below that threshold.

Bone mineral content in 70- and 75-year-old men and women: an analysis of some anthropometric background factors.

The bone mineral content (BMC) in the heel bone of the right foot has been determined in representative samples consisting of 253 men and 309 women aged 70 years, and 105 men and 159 women aged 75, with dual photon absorptiometry in a cross-sectional study. The large number of subjects of the same age makes a detailed analysis of the covariation of anthropometric background variables with the BMC suitable. Lower BMC values at the age of 75 were found for men, but not for women, compared to subjects aged 70. In the present study women at the age of 75 had almost the same mean body weight as those aged 70, while men aged 75 had significantly lower body weight compared to men aged 70. Statistical analysis for conditional dependence showed that, if body weight was kept constant, significantly lower BMC values at the age of 75 were found for women but not for men. Thus, the influence of body weight on BMC seems to be stronger than a cross-sectional age difference of five years. Further analyses showed close correlations between parameters such as body weight, relative weight, body mass index and skinfold thickness with BMC. The more weight the heel bone has to carry, whether it is muscle tissue or fat tissue, the more mineral is found in this bone. It is concluded that, for the lower extremities, body weight must be taken into account in studies of BMC changes, especially in cross-sectional studies and most certainly when analysing the age factor.

Calcaneal bone density reduction in patients with restricted mobility.

This cross-sectional study revealed a prevalence of reduced calcaneal bone density in a population of 49 chronic continuing care patients with restricted mobility. Calcaneal bone density was measured using the Compton gamma ray scattering technique, which permits examination of trabecular bone. Predicted densities were determined from the ages and weights of the subjects. Descriptive factors such as gender, diagnosis, duration of the condition, and muscle tone were correlated with bone density. Twenty-eight patients (57%) had indications of reduced calcaneal bone density. None of the descriptive factors was associated with the variability in bone density ratio (forward stepwise regression analysis, p = NS). The reduced calcaneal density found in these patients with restricted mobility is probably a result of their not bearing weight and the inevitable severe reduction in their physical activity.

[Relationship between calcium salt content in the trunk skeleton and the extremities (calcaneus measurement) (author's transl)]. / Beziehung zwischen Kalksalzgehalt von Stammskelett und Extremitäten (Fersenbeinmessung)

No statistically significant correlation could be found in a comparative investigation regarding the mineral salt content of the calcaneus and the first lumbar vertebral body in the same test person. Conclusions based on localized individual measurements of the mineral salt content of the calcaneus for the respective vertebral body are, in our opinion not possible with the desired exactness. For orthopedic surgeons in the private practice, only the interpreation of a x-ray of the vertebral column can be used in addition to clinical and laboratory findings to diagnose the onset of generalized osteoporosis. In order to keep the source of error as low as possible in the attempt to diagnose osteoporosis from an x-ray, constant, reproduceable conditions for taking the x-ray (same film,same lighting, same film development and same x-ray focus on the same part of the skeleton) must be used for observing the course of the disease.

[Chemical composition of the mineral component of the human vertebrae and calcaneus during hypokinesia]. / Khimicheskii sostav mineral'nogo komponenta pozvonkov i piatochnoi kosti cheloveka posle gipokinezii.

Hypokinesia of 20--42 days lead to a decrease of Ca content and increase of K and Na content in the mineral component of human vertebrae, the Mg and P content remaining unchanged. It is suggested that these changes resulted from shifts in ion metabolism on the surface of hydroxylapatite crystals as well as from increase in the content of calcium phosphate amorphous component. The hypokinesia did not cause chemical changes in the inorganic component of os calcis, probably, due to the low metabolic activity of its microstructures. After hypokinetic exposure the mineral density of vertebrae and os calcis did not differ from the control value, i. e. no osteoporosis was seen.

Broadband ultrasonic attenuation in the os calcis and single photon absorptiometry in the distal forearm: a comparative study.

The measurement of broadband ultrasonic attenuation (BUA) in the os calcis has been described recently but the method has not been compared with other non-invasive techniques for the assessment of bone mass. We have compared the measurement of BUA in the os calcis with single-photon absorptiometry of the distal forearm in 44 subjects. A highly significant positive correlation was found between these two measurements (r = 0.80, p less than 0.001). Day to day repeatability was assessed for both techniques, with coefficients of variation of 3.9% and 1.4%, respectively, being obtained. Broadband ultrasonic attenuation appears to be a potentially useful bone measurement in the appendicular skeleton.

Bone mineral content in the calcaneus after ankle fracture.

The bone mineral content across the calcaneus was measured by gamma absorptiometry in 82 patients with operated on ankle fractures. A mean deviation in bone mineral content between the injured and the uninjured leg of 6 percent was found. Early weight bearing in a walking cast or brace did not influence the process of postfractural osteopenia. Compared with the patients with isolated lateral malleolar fractures, the patients with bimalleolar and trimalleolar fractures were older and had a lower bone mineral content in the calcaneus of their uninjured leg. The percentage of deviation in bone mineral content between the injured and uninjured leg was also greater in patients with more severe fractures.

Bone mass is low in relatives of osteoporotic patients.

STUDY OBJECTIVE: To determine whether the failure to attain normal bone mass in young adulthood contributes to the later development of osteoporotic fractures. DESIGN: Case-control study. SETTING: Referral-based bone clinic at a large teaching hospital. PATIENTS: Sequential sample of 35 asymptomatic relatives, aged 19 to 59 years, of patients with osteoporotic fractures, and 24 patients with osteoporotic fractures. MEASUREMENTS AND MAIN RESULTS: Bone mineral density in the spine was measured by quantitative computed tomographic scanning. Bone mineral content in the os calcis was measured in 19 of the relatives of osteoporotic patients by single-photon absorptiometry. The values for bone mineral density in the spine were corrected to age 50 years with the regression equation derived from the normal values in the controls. The values were lower in relatives of osteoporotic patients than in controls. In men, the mean values (+/- standard deviation [SD]) for relatives were 91 +/- 16 mg/cm3, and for controls, 129 +/- 21 mg/cm3 (P less than 0.001). In women, the mean values for relatives were 96 +/- 17 mg/cm3 and for controls, 126 +/- 19 mg/cm3 (P less than 0.001). In the osteoporotic patients, the corrected mean value for men was 53 +/- 12 mg/cm3, and for women, 77 +/- 20 mg/cm3. The os calcis values did not correlate with the spine values and were mostly well within the normal range. CONCLUSIONS: Mean bone mass is lower in apparently healthy young and middle-aged adult relatives of osteoporotic patients than in normal persons with no family history of osteoporosis. Our findings suggest that the failure to attain an adequate peak bone mass may play an important role in the later development of osteoporotic fractures. Relatives of osteoporotic patients should be advised to have measurements of bone mass taken. This measurement should be taken at the spine, because peripheral sites do not appear to provide adequate information about early osteoporosis.