Vertebral fracture prevalence in a referral population of 750 Canadian men and women.

AIM: To establish the prevalence of vertebral fracture (VF) in a representative sample of 750 Canadians and to examine the relationships between VF prevalence and bone mineral density (BMD) at the spine and proximal femur. MATERIALS AND METHODS: X-ray-based dual-photon absorptiometry (DXA) was used to perform measurements of lumbar spine BMD, proximal femur BMD, and VF assessment (VFA). RESULTS: Two hundred and fifty-nine VFs were identified in 156 patients and the prevalence of unknown or unsuspected VF was 18.7%. For premenopausal women and for men, there was no difference in BMD at either the spine or the hip whether or not there was at least one VF. For postmenopausal women, BMD of the total region of the proximal femur was statistically lower (p < 0.001) in women with at least one VF whereas spine BMD only tended to be less (0.10 > p > 0.05). Proximal femur BMD was lower for postmenopausal women with more VF, while spine BMD was virtually unchanged as the number of VF increased. Neither spine nor hip BMD was lower for men with more VF. A strong association was observed in postmenopausal women between an age-dependent increase in VF prevalence and a reduction in femoral BMD. Such an association was not present in men. CONCLUSION: VFs are common, are often independent of either spine or hip BMD, and frequently go unnoticed. Therefore, VFA should be part of a routine assessment of fracture risk.

Quantitative analysis of subchondral sclerosis of the tibia by bone texture parameters in knee radiographs: site-specific relationships with joint space width.

OBJECTIVES: To determine the ability of radiographic bone texture (BTX) parameters to quantify subchondral tibia sclerosis and to examine clinical relevance for assessing osteoarthritis (OA) progression. We examined the relationship between BTX parameters and each of (1) location-specific joint space width (JSW) [JSW(x)] and minimum JSW (mJSW) of the affected compartment, and (2) knee alignment (KA) angle in knee radiographs of participants undergoing total knee arthroplasty (TKA). DESIGN: Digitized fixed-flexion knee radiographs were analyzed for run-length and topological BTX parameters in a subchondral region using an algorithm. Medial JSW(x) was computed at x=0.200, 0.225, 0.250 and 0.275 according to a coordinate system defined by anatomic landmarks. mJSW was determined for medial and lateral compartment lesions. KA angles were determined from radiographs using an anatomic landmark-guided algorithm. JSW measures and the magnitude of knee malalignment were each correlated with BTX parameters. Reproducibility of BTX parameters was measured by root-mean square coefficients of variation (RMSCV%). RESULTS: Run-length BTX parameters were highly reproducible (RMSCV%<1%) while topological parameters showed poorer reproducibility (>5%). In TKA participants (17 women, 13 men; age: 66+/-9 years; body mass index (BMI): 31+/-6 kg m(-2); WOMAC: 41.5+/-16.1; Kellgren-Lawrence score mode: 4), reduced trabecular spacing (Tb.Sp) and increased free ends (FE) were correlated with decreased JSW after accounting for BMI, gender and knee malalignment. These relationships were dependent on site of JSW measurement. CONCLUSION: High reproducibility in quantifying bone sclerosis using Tb.Sp and its significant relationship with JSW demonstrated potential for assessing OA progression. Increased trabecular FE and reduced porosity observed with smaller JSW suggest collapsing subchondral bone or trabecular plate perforation in advanced knee OA.

Accounting for body size deviations when reporting bone mineral density variables in children.

UNLABELLED: In a child, bone mineral density (BMD) may differ from an age-expected normal value, not only because of the presence of disease, but also because of deviations of height or weight from population averages. Appropriate adjustment for body size deviations simplifies interpretation of BMD measurements. INTRODUCTION: For children, a bone mineral density (BMD) measurement is normally expressed as a Z score. Interpretation is complicated when weight or height distinctly differ from age-matched children. We develop a procedure to allow for the influence of body size deviations upon measured BMD. METHODS: We examined the relation between body size deviation and spine, hip and whole body BMD deviation in 179 normal children (91 girls). Expressions were developed that allowed derivation of an expected BMD based on age, gender and body size deviation. The difference between measured and expected BMD was expressed as a HAW score (Height-, Age-, Weight-adjusted score). RESULTS: In a second independent sample of 26 normal children (14 girls), measured spine, total femur and whole body BMD all fell within the same single normal range after accounting for age, gender and body size deviations. When traditional Z scores and HAW scores were compared in 154 children, 17.5% showed differences of more than 1 unit and such differences were associated with height and weight deviations. CONCLUSION: For almost 1 in 5 children, body size deviations influence BMD to an extent that could alter clinical management.

Quantitative, small bore, 1 Tesla, magnetic resonance imaging of the hands of patients with rheumatoid arthritis.

OBJECTIVE: To determine if quantitative hand images obtained from an office-based MRI extremity scanner reliably distinguish patients with rheumatoid arthritis from controls. METHODS: The hands of 39 patients suffering from rheumatoid arthritis were imaged using a small bore, 1.0 Tesla Magnetic Resonance Imager. Non-contrast images of the metacarpophalangeal joints and wrist joints were evaluated using a method based on the validated rheumatoid arthritis magnetic resonance imaging system (RAMRIS). The extent and degree of synovitis, bone edema and bone erosions was assessed. Derived scores were compared with the corresponding scores for groups of younger (n=14) and older (n=27) controls with no signs or symptoms of joint disease. RESULTS: The mean (+/-standard error) total joint scores were 0.3+/-0.2 for young controls, 11.5+/-2.4 for older controls and 34.1+/-6.0 for the patients with rheumatoid arthritis. The greatest difference between rheumatoid patients and older controls was observed for synovitis with scores that were greater by a factor of almost 6.5. Scores for erosions and edema were factors of 2.9 and 2.3 greater in rheumatoid arthritis than in controls. The relationship between scores for the same joints on the dominant and non-dominant sides was generally stronger than the relationship between the metacarpophalangeal and wrist joints of the same hand. CONCLUSION: These observations indicate that scoring of hand images obtained from a small bore, office based, 1.0 Tesla MR imager have clinical validity and may be used to distinguish patients with rheumatoid arthritis from aged matched controls.

In vivo study of an x-ray fluorescence system to detect bone strontium non-invasively.

An x-ray fluorescence (XRF) system using 125I as the source was developed to measure strontium in bone in vivo. As part of an in vivo pilot study, 22 people were measured at two bone sites, namely the index finger and the tibial ankle joint. Ultrasound measurements were used to obtain the soft tissue thickness at each site, which was necessary to correct the signal for tissue attenuation. For all 22 people, the strontium peak was clearly distinguishable from the background, proving that the system is able to measure Sr in vivo in people having normal bone Sr levels. Monte Carlo simulations were carried out to test the feasibility and the limitations of using the coherently scattered peak at 35.5 keV as a means to normalize the signal to correct for the bone size and shape. These showed that the accuracy of the normalized Sr signal when comparing different people is about 12%. An interesting result arising from the study is that, in the measured population, significantly higher measurements of bone Sr concentration were observed in continental Asian people, suggesting the possibility of a dietary or race dependence of the bone Sr concentration or a different bone biology between races.

The decrease in population bone lead levels in Canada between 1993 and 2010 as assessed by in vivo XRF.

Objective and Approach: A study, conducted in Toronto, Canada, between 2009 and 2011, measured the bone lead concentrations of volunteers aged 1-82 years using in vivo x-ray fluorescence (XRF) technology. MAIN RESULTS: Bone lead levels were lower compared to Ontario in vivo XRF studies from the early 1990s. In adults, the slope of tibia lead content versus age was reduced by 36-56%, i.e. bone lead levels for a given age group were approximately half compared to the same age group 17 years prior. Further, bone lead levels of individuals fell over that time period. In 2010, an average person aged 57 years had a bone lead level approximately 1/3 less than their bone lead level age 40 years in 1993. Using this data, the half-lives of lead in the tibia were estimated as 7-26 years. Tibia lead levels were found to be low in children. The reduction in bone tibia content in children was not significant (p = 0.07), but using data from additional north eastern US studies, there is evidence that childhood tibia stores are lower than in the 1990s. SIGNIFICANCE: In vivo XRF analysis shows that there has been a reduction in the level of lead in bone in Canada over the last two decades. Public health measures have been very successful in reducing ongoing exposure to lead and in reducing bone lead stores.

Osteopenia in children surviving brain tumours.

Osteopenia has been reported in children surviving acute lymphoblastic leukaemia, apparently as a consequence of therapy. It has been suggested that cranial irradiation may play a crucial role in this disorder. To explore that possibility, survivors of brain tumours in childhood, all of whom had received radiotherapy, were examined for evidence of bone mineral loss. 19 children were assessed, on average at 7 years after treatment. Measurements of growth velocities, plain radiography of the skeleton, bone densitometry, health-related quality of life and physical activity were undertaken. Growth hormone (GH) deficiency had been detected in 6 children and 5 had received GH replacement, for a minimum of more than 3 years. 9 children were radiographically osteopenic (including the 5 who had received GH). Z scores for bone mineral density (BMD) were negative in the majority of children. Health-related quality of life was less and pain more frequent in those with low BMD scores. Pain was correlated negatively with both free-time activity and seasonal activity (P < 0.01). Osteopenia is a common sequel of therapy in children with brain tumours. Those with osteopenia have more pain and more compromised, health-related quality of life than those who are not osteopenic, and pain significantly limits physical activity. The pathogenesis of osteopenia in these children is still uncertain, but is likely to be multifactorial.

Abnormal brain scans: Contribution of blood radioactivity to image.

Images obtained with 99m-Tc-labeled red blood cells were compared with 99m-Tc-pertechnetate scans in 26 patients with primary and secondary brain tumors, intracerebral infcts, and hemorrhage. The results indicated that the contribution of blood pool radioactivity to a positive brain scan was minor.

The effects of long-term heparin therapy during pregnancy on bone density. A prospective matched cohort study.

We performed a prospective matched cohort study to investigate the effects of long-term (> 1 month) heparin therapy on lumbar spine bone density. Twenty-five women who received heparin during pregnancy, and 25 matched controls underwent dual photon absorptiometry of the lumbar spine in the post-partum period. Zero of 25 heparin-treated patients developed fractures. Heparin-treated patients had a 0.082 g/cm2 lower bone density compared to untreated controls, which is clinically and statistically significant (p = 0.0077). There were 6 matched pairs in which only the heparin-treated patient had a bone density below 1.0 g/cm2, compared to only one pair in which only the control patient had a bone density below this level (p = 0.089). The correlation coefficients of the difference in bone density in each matched pair, and the duration of heparin therapy, the mean daily dose, and the total dose of heparin were 0.042, - 0.015, and 0.021, respectively; none of these values is statistically significant. We conclude: 1) long-term heparin therapy was associated with a significant reduction in bone density, although fractures are uncommon, 2) there was no significant correlation between lumbar bone density and the dose or duration of heparin.

The reproducibility of 109Cd-based X-ray fluorescence measurements of bone lead.

We assessed the reproducibility of X-ray fluorescence-based lead measurements from multiple measurements made on a low-concentration plaster of paris phantom and in five subjects measured five times on two occasions. Over a 6-month period, 220 measurements of the same phantom were obtained and showed a standard deviation of 1.29 micrograms Pb (g plaster of paris)-1. The two sets of in vivo measurements were made 10 months apart and revealed a mean standard deviation of 3.4 micrograms Pb (g bone mineral)-1 and 5.1 micrograms Pb (g bone mineral)-1 for males and females, respectively. Our measured standard deviation exceeded by 20-30% the calculated standard deviation associated with a single measurement both in the phantom and in subjects. This indicates that some variance is introduced during the measurement process. Operator learning and consistency significantly minimized this increased variability. Measured lead concentrations of the left and right tibia in 14 subjects showed no significant differences between legs. As a result, either tibia can be sampled and compared over time. The levels of reproducibility we report here mean that X-ray fluorescence-based determinations of bone lead concentrations are reliable both over the short and long term. Thus, reasonably sized confidence intervals can be placed on detected changes in concentration and should permit acquisition of longitudinal data within a reasonable length of time.

Accumulated body burden and endogenous release of lead in employees of a lead smelter.

Bone lead levels for 367 active and 14 retired lead smelter workers were measured in vivo by X-ray fluorescence in May-June 1994. The bone sites of study were the tibia and calcaneus; magnitudes of concentration were used to gauge lead body burden. Whole blood lead readings from the workers generated a cumulative blood lead index (CBLI) that approximated the level of lead exposure over time. Blood lead values for 204 of the 381 workers were gathered from workers returning from a 10-month work interruption that ended in 1991; their blood level values were compared to their tibia and calcaneus lead levels. The resulting relations allowed constraints to be placed on the endogenous release of lead from bone in smelter works. Calcaneus lead levels were found to correlate strongly with those for tibia lead, and in a manner consistent with observations from other lead industry workers. Relations between bone lead concentration and CBLI demonstrated a distinctly nonlinear appearance. When the active population was divided by date of hire, a significant difference in the bone lead-CBLI slope emerged. After a correction to include the component of CBLI existing before the workers' employment at the smelter was made, this difference persisted. This implies that the transfer of lead from blood to bone in the workers has changed over time, possibly as a consequence of varying exposure conditions.

Hormone replacement therapy may reduce the return of endogenous lead from bone to the circulation.

Hormone replacement therapy (HRT) in postmenopausal women suppresses the increase in bone resorption expected as circulating levels of endogenous estrogen decline. We tested the hypothesis that bone lead content might remain elevated in women on HRT. Fifty six women who at recruitment were on average 35 years postmenopausal were placed on calcium supplementation. Six months later 33 of these women were prescribed either low dose or moderate dose hormone replacement in addition to the calcium supplementation. After approximately 4 years of hormone replacement, lead content was measured at the tibia and calcaneus by in vivo fluorescence excitation, and lead concentrations were measured in serum, whole blood, and urine. Women not taking hormones had significantly lower lead concentrations in cortical bone compared to all women on HRT (p = 0.007). Tibia lead content (mean +/- SD) for women on calcium only was 11.13 +/- 6.22 microgram/g bone mineral. For women on HRT, tibia bone lead was 19.37 +/- 8.62 micrograms/g bone mineral on low-dose HRT and 16.87 +/- 11.68 micrograms/g bone mineral on moderate-dose HRT. There were no differences between groups for lead concentrations measured in trabecular bone, whole blood, serum or urine. Hormone replacement maintains cortical bone lead content. In women not on HRT, there will be a perimenopausal release of lead from bone.

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.

In vivo measurement of absolute tissue iodine content by fluorescence excitation.

A method based on the measurement of fluorescent and transmitted photons has been developed for the quantitative determination of stable iodine concentrations in tissues. The results are independent of the thickness of the material surrounding the measuring site. The method yields an accuracy of better than 3% for both Ge semiconductor and NaI(TI)detector arrangements.

Long-term resistance training in the elderly: effects on dynamic strength, exercise capacity, muscle, and bone.

We examined the effects of 42 weeks of progressive weight-lifting training on dynamic muscle strength, peak power output in cycle ergometry, symptom limited endurance during progressive treadmill walking and stair climbing, knee extensor cross-sectional areas, and bone mineral density and content in healthy males and females aged 60-80 years, currently enrolled in a 2-year resistance training program. Subjects were randomized into either exercise (EX) or control (CON) groups (60-70 years: 38 males and 36 females; 70-80 years: 25 males and 43 females). EX trained several muscle groups twice per week for 42 weeks at intensities ranging from 50-80% of the load that they could lift once only (1 RM); CON did usual daily activities. After the 10 months there was no change in 1 RM strength in CON, but significant gains (mean increases up to 65%) in EX (no independent age or gender effects); 30% and 47% of the increase in 1 RM had occurred by 6 and 12 weeks, respectively. In EX, the 7.1% increase in peak cycling power output was significantly greater than in CON (+1.1%). The 17.8% improvement in symptom limited treadmill walking endurance was also greater than in CON (+3.4%), but the difference between groups during stair climbing was not significant (EX + 57%, CON + 33%). The cross-sectional areas of the knee extensors increased significantly by 5.5% in EX but were unchanged in CON. There were no changes in bone mineral density or content in either group. We conclude that long-term resistance training in older people is feasible and results in increases in dynamic muscle strength, muscle size, and functional capacity.

A longitudinal trial of weight training in the elderly: continued improvements in year 2.

We conducted a 2-year (42 weeks of consecutive training in each year, separated by 10 weeks of testing and vacation time) randomized, controlled trial of weight training in 142 healthy male and female subjects, aged 60 to 80 years. Measurements included dynamic strength, symptom-limited endurance in cycling, treadmill walking and stair climbing, muscle size, and bone mineral density and content of the lumbar spine and whole body. One hundred and thirteen subjects completed the study (57 exercise, 56 control), with a mean attendance of 85% among the exercisers. Muscle strength was unchanged in the control subjects but increased (collapsed across age and gender) from 32% (leg press) to 90% (military press) in the exercisers. Symptom-limited endurance in cycling, treadmill walking, and stair climbing increased in the exercisers by (mean +/- SE) 6.2 +/- 0.8%, 29.2 +/- 7.3%, and 57 +/- 12%, respectively; the only change in the controls was an unanticipated 33% increase in stair climbing performance during the first year. These values were unchanged in the controls. Cross-sectional area of the knee extensors increased by 8.7 +/- 0.9% in the trained subjects and was unchanged in controls. Measures of whole body, lumbar spine bone mineral density, and lumbar spine bone mineral content were unchanged in the exercisers, but whole body bone mineral content decreased by 1%. In contrast, there were small increases (< 4.0%) in bone mineral density among the controls. Long-term weight training proved to be a safe and well-tolerated mode of exercise for the elderly. Increased strength was associated with muscle hypertrophy in each year, and with increased endurance in cycling, walking, and stair climbing. There were no changes in bone mineral density but a small reduction in whole body bone mineral content.

Accuracy of measurements of small changes in soft tissue mass by use of dual-photon absorptiometry.

Dual-photon absorptiometry (DPA) has recently been applied to the assessment of body composition. To evaluate the accuracy of DPA in detecting small changes in the lean soft tissue mass, we performed DPA with the use of the Norland 2600 Dichromatic densitometer on six healthy adult males before and after a 30-ml/kg transfusion of saline and before and after exercise in a warm environment, resulting in a greater than or equal to 1-kg weight loss. Absolute weight [baseline pretransfusion r2 = 0.999, standard error of estimate (SEE) = 590 g; posttransfusion r2 = 0.999, SEE = 300 g; baseline pretranspiration r2 = 0.999, SEE = 230 g; posttranspiration r2 = 0.999, SEE = 240 g] was accurately reflected in DPA total mass. Weight changes due to transfusion were poorly reflected by changes in DPA total mass (r2 = 0.417, SEE = 404 g). However, changes posttranspiration were accurately reflected in the DPA total mass (r2 = 0.886, SEE = 106 g posttranspiration). Similarly, weight changes due to transfusion were poorly measured by changes in DPA soft mass (r2 = 0.478, SEE = 365 g), but changes posttranspiration were highly correlated with DPA soft mass changes (r2 = 0.909, SEE = 92 g). Weight changes were not reflected by changes in the DPA lean soft tissue mass (r2 = 0.006, SEE = 1,737 posttransfusion, r2 = 0.094, SEE = 1,038 g posttranspiration). DPA-derived nonfat mass was highly correlated with skinfold-derived nonfat mass (r2 = 0.96, SEE = 2,400 g). Accuracy of total and soft tissue measurements implied correct mineral mass assessment.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship among running mileage, bone density, and serum testosterone in male runners.

Our purpose was to investigate the relationship between running volume and bone mineral mass in adult male runners. Whole body and regional bone mineral density were determined by dual-photon absorptiometry in 22 sedentary controls and 53 runners who were selected according to their running mileage to fall into a 5- to 10-, 15- to 20-, 25- to 30-, 40- to 55-, or 60- to 75-mile/wk group. All groups were of similar age (20-45 yr) and nutritional status, as determined by 7-day food records. Regional sites for bone density measurements included the trunk, spine, pelvis, thighs, and lower legs. In addition, serum total testosterone was determined in each subject and computed tomography scans were made of the lower legs in 34 subjects to assess bone cross-sectional area. No significant differences were detected for bone density measurements with the exception of the lower legs where it was significantly (P less than 0.05) greater for the 15- to 20-mile/wk group than for the control and 5- to 10-mile/wk groups. With mileage greater than 20 miles/wk, bone density of the lower legs showed no further increase and, in fact, tended to decrease, so that for the 60- to 75-mile/wk group it was similar to that of the controls. Cross-sectional area of the tibia and fibula when normalized to body weight tended to be greater as weekly mileage increased and was significantly greater in the 40- to 55-mile/wk runners than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of three techniques for body composition analysis in cystic fibrosis.

Body composition analysis is an important component of nutritional assessment in cystic fibrosis (CF). No gold standard of measurement exists, and techniques applicable to healthy populations may be unsuitable for CF patients. We assessed lean body mass (LBM) in 12 children with CF by skinfold (SK) measurements, bioelectrical impedance analysis (BIA), and dual-photon absorptiometry (DPA) and repeated these measures in 10 subjects 6 mo later. SK and DPA measures in eight older CF patients and eight healthy controls were compared to evaluate any effect of disease on estimates of LBM by use of DPA. Good agreement between the measures was seen at baseline and 6 mo by use of concordance plots. However, the limits of agreement between measures ranged up to 19% of SK-derived LBM measures (baseline: SK and DPA, 2.63 to -3.93 kg; SK and BIA, 2.36 to -1.24 kg; BIA and DPA, 1.88 to -4.28 kg; 6 mo: SK and DPA, 2.10 to -3.58 kg; SK and BIA, 6.28 to -5.49 kg; BIA and DPA, 5.53 to -7.79 kg). The change in LBM over 6 mo did not correlate among the three measures. Only BIA change in LBM correlated with weight change (r = 0.716, P < 0.02), probably due to the inclusion of weight in the regression equations for determining LBM from impedance. The relationship between SK and DPA measures did not differ between the CF and control groups, suggesting that there was no effect of disease on the DPA measure. The results suggest that none of these methods is precise enough to follow short-term changes in the nutritional status of CF patients longitudinally.

Falciform ligament. A possible twist?

Abdominal pain radiating to the right upper quadrant, producing peritoneal signs, developed in a 30-year-old pregnant woman. At surgery, she was found to have an infarction of the falciform ligament that was excised.