Bone gained from physical activity and lost through detraining: a longitudinal study in young males

The aim of this study was to investigate the effect of training and detraining on bone mineral density of both weight-bearing and non-weight-bearing bone in a cohort of young males who participated in ice hockey training. Forty-three healthy adolescent ice hockey players (16.7±0.6 years) training for a mean of 9.7±2.4 h/week and 25 control subjects (16.8±0.3 years) training for 2.1±2.7 h/week, were included in this longitudinal study. Bone mineral density (BMD, g/cm²) of the arms, the dominant and non-dominant humerus, dominant and non-dominant femur, and the right femoral neck, total hip, and bone area of the femur, humerus and hip were measured at baseline and again after 30 and 70 months using dual-energy X-ray absorptiometry. From baseline to the first follow-up, athletes gained significantly more BMD in the femoral neck (0.07 versus 0.03 g/cm²) and arms (0.09 versus 0.06 g/cm²) compared with the controls (P=0.04 for both). Between the first and the second follow-up, 21 ice hockey players stopped their active sports career. These men lost significantly more BMD at the femoral neck (–0.02 versus –0.10 g/cm², P<0.001), total hip (–0.05 versus –0.09, P=0.04), dominant (0.02 versus –0.03 g/cm², P=0.009) and non-dominant humerus (0.03 versus –0.01 g/cm², P=0.03) than the still active ice hockey players (n=22). At the second follow-up examination, at 22 years of age, the former ice hockey players still had significantly higher BMD at the non-dominant humerus than the controls (P<0.01). During the total study period, the still active athletes (n=22) gained significantly more BMD compared with the controls at the femoral neck (0.09 g/cm²; P=0.008), total hip (0.05 g/cm², P=0.04) and arms (0.07 g/cm²; P=0.01). No differences were seen in bone areas when comparing the different groups. In conclusion, training associated with ice hockey is related to continuous accumulation of BMD after puberty in males. Reduced activity is followed by BMD loss within 3 years of cessation of sports career at predominantly weight-bearing sites. The effects are confined to bone density and not bone size.     

Preferential low bone mineral density of the femoral neck in patients with a recent fracture of the proximal femur

Bone mass is an important determinant of resistance to fractures. Whether bone mineral density (BMD) in subjects with a fracture of the proximal femur (hip fracture) is different from that of age-matched controls is still debated. We measured BMD of the femoral neck (FN) on the opposite side to the fracture, as well as femoral shaft (FS) and lumbar spine (LS) BMD by dual-photon absorptiometry in 68 patients (57 women and 11 men, mean age 78.8±1.0) 12.4±0.8 days after hip fracture following a moderate trauma. These values were compared with BMD of 93 non-fractured elderly control subjects (82 women and 11 men), measured during the same period. As compared with the controls, FN BMD was significantly lower in fractured women (0.592±0.013 v. 0.728±0.014 g/cm²,P<0.001) and in fractured men (0.697±0.029 v. 0.840±0.052,P<0.05). Expressed as standard deviations above or below the mean BMD of age and sex-matched normal subjects (Z-score), the difference in FN BMD between fractured women and controls was highly significant (–0.6±0.1 v. +0.1±0.1,P<0.001). As compared with mean BMD of young normal subjects, BMD was decreased by 36.9±1.4 and 22.4±1.5% (P<0.001) in fractured and control women, respectively. There was no significant difference between FN BMD of 33 women with cervical and 24 with trochanteric hip fractures (0.603±0.017 v. 0.577±0.020). FN BMD was lower than 0.705 g/cm² in 90% of fractured women. The prevalence of fracture increased with decreasing FN BMD, reaching 100% with values below 0.500 g/cm². FS and LS BMD were significantly lower in women with hip fracture than in controls (1.388±0.036 v. 1.580±0.030,P<0.001, for FS, and 0.886±0.027 v. 0.985±0.023,P<0.01, for LS), but these differences were not significant when expressed as a Z-score. In men with a recent hip fracture, FS BMD was significantly lower than in controls (1.729±0.096 v. 2.069±0.062,P<0.01), but the difference at the LS level did not reach statistical significance. These results indicate that both women and men with a recent hip fracture had decreased bone mineral density of the femoral neck, femoral shaft and lumbar spine. However, the difference appeared to be of higher magnitude for the femoral neck suggesting a preferential bone loss at this site.     

Bone mineral density in patients with cervical and trochanteric fractures of the proximal femur

The bone mineral density (BMD) of the proximal femur, spine and radius shaft was determined in 75 women with atraumatic fractures of the proximal femur (FXf) (average age: 70.1±9.6 years) and 51 controls of similar age. Fractures were classified as either cervical (n=36) or trochanteric (n=39) on the basis of radiographic and surgical finding. The BMD of spine and proximal femur was determined by dual-photon absorptiometry (Lunar DP3) and the BMD of the radius shaft by single photon absorptiometry. The BMD of patients with FXf was significantly decreased over all skeletal sites compared to controls of similar age. No significant correlation was found between age and the BMD of the femoral neck in patients with FXf. Patients with trochanteric FXf were older and thinner (average: age, 72.9±9.4 years; weight, 53.1±7.8 kg) compared with patients with cervical fractures (age, 67.2±8.9 years; weight, 59.3±8.3 kg). Likewise the BMD of trochanteric FXf was lower at all measured sites: femoral neck, 0.548±0.066 g/cm² vs 0.624±0.055 g/cm² (P<0.001); L2-L4, 0.799±0.115 g/cm² vs 0.925±0.106 g/cm² (P<0.001); radius shaft, 0.454±0.057 g/cm² vs 0.502±0.083 g/cm² (P<0.05). Of the patients with trochanteric fractures 66% had concomitant vertebral fractures, while this occurred in only 28% of the patients with cervical fractures (P (Fisher)=0.0007). In summary, females with trochanteric FXf are older, thinner, have less bone mass in all measured sites and suffer with a significantly greater frequency of vertebral fractures. These patients have a generalized osteoporosis of the skeleton. Patients with cervical FXf seem to have more specific loss of the proximal femur (regional osteoporosis). The physiopathological process leading to trochanteric and cervical fractures is probably different.     

Cross-Sectional Study of Weight-Bearing Activity on Proximal Femur Bone Mineral Density

In this cross-sectional study we investigated the effect of compressive and tensile forces applied on the proximal femur during weight-bearing activities. Ninety-seven men (29.9 ± 1.7 years) were divided into two groups: 69 exercisers who had practiced regular high-impact weight-bearing activities for at least 5 years and 28 controls who had been sedentary for at least 5 years. The maximum isometric hip abduction strength was measured. The bone mineral density (BMD) of the femoral neck and the greater trochanter was assessed using dual-energy X-ray absorptiometry (DXA). Controls were considered as the reference population to calculate the Z score. Mean BMD values of the femoral neck were 0.97 g/cm² on both sides in the exercisers and 0.83 g/cm² on the right side and 0.84 g/cm² on the left side in the controls. Mean BMD values of the greater trochanter were 0.86 g/cm² on the right side and 0.87 g/cm² on the left side in the exercisers, 0.73 g/cm² on the right side and 0.72 g/cm² on the left side in the controls. The BMD was significantly higher in exercisers at both trochanteric and cervical sites (P= 0.0001). Both left and right hip abduction strength was significantly greater in the exercisers than in the controls (P < 0.05) and was positively correlated to cervical and trochanteric BMD (P < 0.01). In the exerciser group, the trochanteric Z score was higher than the cervical Z score at both right (P= 0.06) and left (P= 0.002) sides. Therefore, the proximal femoral BMD was significantly greater in exercised subjects as compared with sedentary controls. The difference was observed at the level of both the femoral neck (where it is known anatomically that only compressive gravitational forces are exerted) and the greater trochanter (where it is known that tensile forces are exerted). This result suggests the participation of both compressive and tensile forces in the mechanisms by which exercise influences bone trophicity. Received: 19 November 1997 / Accepted: 7 August 1998     

Bone mineral density in the femur and lumbar vertebrae decreases after twelve weeks of diabetes in spontaneously diabetic-prone BB/Worcester rats

The accumulated data indicate that bone mineral density (BMD) is decreased in humans with insulin-dependent diabetes mellitus. The purpose of this study was to prospectively determine sequential lumbar and femoral BMD utilizing dual energy X-ray absorptiometry in rats that spontaneously become diabetic to determine if weight and blood glucose control would prevent the diabetes-related bone mass changes. BMD of the lumbar spine and femur was measured prior to the onset of diabetes and at 3-week intervals after the diagnosis of diabetes for 12 weeks in 14 diabetes-prone BB/Wor rats (DP) and eight diabetes-resistant BB/Wor control rats (DR). At 12 weeks, the lumbar (0.238±0.013 vs 0.262±0.007 g/cm², P<0.001) and femoral (0.313±0.013 vs 0.343±0.013 g/cm², P<0.001) BMD were significantly lower in the DP rats despite significantly greater body weights (387±26 vs 329±46 g, P<0.001) and plasma glucose levels of only 178 mg/dl. There was no difference in plasma values of calcium, phosphorus, osteocalcin, or tartrate-resistant acid phosphatase between groups or differences in osteoblast numbers in histologic sections. There was a significant (P<0.001) decrease in plasma creatinine in the diabetic animals. The results indicate that in this animal model of type I diabetes, spine and femoral BMD do not increase comparable to control despite weight and blood glucose control. This would suggest that the diabetic condition itself affects bone mass in the absence of weight loss and poor blood glucose control.     

Reduced hip bone mineral density is related to physical fitness and leg lean mass in ambulatory individuals with chronic stroke

Following a stroke, the reduced level of physical activity and functional use of the paretic leg may lead to bone loss and muscle atrophy. These factors and the high incidence of falls may contribute to hip fractures in the stroke population. This study was the first to examine total proximal femur bone mineral content (BMC) and bone mineral density (BMD) and their relationship to stroke-specific impairments in ambulatory individuals with chronic stroke (onset >1 year). We utilized dual-energy X-ray absorptiometry (DXA) to acquire proximal femur and total body scans on 58 (23 women) community-dwelling individuals with chronic stroke. We reported total proximal femur BMC (g) and BMD (g/cm²) derived from the proximal femur scans, and lean mass (g) and fat mass (g) for each leg derived from the total body scans. Each subject was evaluated for ambulatory capacity (Six-Minute Walk Test), knee extension strength (hand-held dynamometry), physical fitness [maximal oxygen uptake (VO₂max)] and spasticity (Modified Ashworth Scale). Results showed that the paretic leg had significantly lower proximal femur BMD, lean mass and percent lean mass, but higher fat mass than the non-paretic leg for both men and women. Proximal femur BMD of the paretic leg was significantly related to ambulatory capacity ( r =0.33, P =0.011), muscle strength ( r =0.39, P =0.002), physical fitness ( r =0.57, P <0.001), but not related to spasticity ( r =–0.23, P =0.080). Multiple regression analysis showed that lean mass in the paretic leg was a major predictor ( r ²=0.371, P <0.001) of the paretic proximal femur BMD. VO₂max was a significant predictor of both paretic proximal femur BMD ( r ²=0.325, P <0.001) and lean mass in the paretic leg ( r ²=0.700, P <0.001). Further study is required to determine whether increasing physical fitness and lean mass are important to improve hip bone health in chronic stroke.     

Prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in community dwelling postmenopausal Hungarian women

Hypovitaminosis D can result in low bone mass. The prevalence of hypovitaminosis D has public health implications, especially where data are lacking. Since diet and sunlight are the two souces of vitamin D, the results obtained in one geographical region may not be universally applicable. The aim of this study is to characterize the prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in community dwelling postmenopausal Hungarian women. We determined serum levels of 25-hydroxyvitamin D (25-OH-D), PTH, osteocalcin (OC), degradation products of C-terminal telopeptides of type-I collagen (CTx), dietary calcium intake and BMD at L2–L4 lumbar spine (LS) and femur neck (FN) in 319 randomly selected ambulatory postmenopausal women. The prevalence of hypovitaminosis D (serum 25-OH-D50 nmol/l) was 56.7%. On comparing patients with normal and low 25-OH-D, a significant difference was found in age (61.6±8.5 years versus 67.3±9.9 years; P<0.001), PTH (3.9±1.9 pmol/l versus 4.3±2.7 pmol/l; P<0.05), FN BMD (0.802±0.123 g/cm² versus 0.744±0.125 g/cm²; P<0.001) and dietary calcium intake (714.4±199.4 g/day versus 607.9±233 g/day; P<0.001). Osteoporotic patients had a significantly lower 25-OH-D (37.6±19.8 nmol/l versus 56.4±24 nmol/l; P<0.001) and dietary calcium intake (519.2±244.5 mg/day versus 718.2±164.3 mg/day; P<0.001). After controlling for all other variables, 25-OH-D was found to be significantly associated with age, the average hours of sunshine in the 3 months prior to 25-OH-D level determination and dietary calcium intake (r ²=0.190; P<0.001). For FN BMD, significant independent predictors were age, body mass index, 25-OH-D and dietary calcium intake (r ²=0.435; P<0.001). The prevalence of hypovitaminosis D during spring, summer, autumn and winter was 71%, 46.3%, 49.4% and 56.7%, respectively. There was significant seasonal variation in 25-OH-D, PTH, OC, calcium intake and FN BMD. There is a high prevalence of hypovitaminosis D in healthy postmenopausal Hungarian women, and FN BMD is associated with serum 25-OH-D and dietary calcium intake.     

Bone Mineral Density of Opposing Hips Using Dual Energy X-Ray Absorptiometry in Single-Beam and Fan-Beam Design

Bone densitometry focuses on bone mineral area density (BMD in g/cm²) of the proximal femur and spine in anterior-posterior (AP) projections. Artifacts, such as osteoarthritis and osteophytic calcifications (OC) influence spine BMD, especially in AP scans. If only two sites are measured, as is usual in clinical practice, there may be advantages to measuring both femora rather than one femur and the spine. This would not be useful, however, if there was strong symmetry between the two sides. Furthermore, fan beam (FB) techniques have become available for measuring BMD with less data acquisition time. We compared densitometry of opposing femora in 421 patients (369 women, mean age 59.0 ± 4.8; 52 men, mean age 56.9 ± 7.4) using dual-energy X-ray absorptiometry (DXA): both single-beam (SB) and FB modes were evaluated. The precision errors in vivo (short- and midterm) of total BMD were 0.7% for both SB and FB. The total BMD and BMC of the left hip (0.817 ± 0.124 g/cm², 31.3 ± 6.4 g) were significantly (P < 0.001) higher (2–3%) than the corresponding values of the right hip (0.801 ± 0.125 g/cm², 30.3 ± 6.3 g) in both SB and FB (left BMD 0.802 ± 0.117 g/cm², BMC 30.0 ± 6.2 g versus right BMD 0.795 ± 0.117 g/cm², BMC 29.3 ± 6.3 g) modes. However, BMD of the femoral neck and Ward's triangle were not significantly (P > 0.05) different between the two sides. The FB results were generally 2% lower than SB results. There were highly significant (P < 0.001) correlations (r > 0.9) between both hips using both SB and FB. For diagnostic procedures and longitudinal studies, one should consider that there are bilateral differences of femur BMD, as well as differences between FB and SB scan modes.     

Symmetry of Bone Mineral Density at the Proximal Femur with Emphasis on the Effect of Side Dominance

The symmetry and effect of side dominance on the bone mineral density (BMD) of proximal femur was evaluated in 266 normal Chinese women with a dual photon absorptiometer (DPA, Norland 2600). The BMDs of the femoral neck, trochanter, and Ward's triangle at the proximal femur in the dominant leg (BMDd) were compared with those of the nondominant side (BMDn). The linear regression of BMDd and BMDn of the corresponding regions at the proximal femur showed a good correlation (r = 0.893–0.941, SEE = 0.052–0.062 g/cm²). The paired difference of proximal femoral BMD was −0.002 ± 0.062 g/cm² for the femoral neck, 0.003 ± 0.054 g/cm² for the trochanter, and 0.008 ± 0.062 g/cm² for the Ward's triangle. The ratio of asymmetry for femoral neck BMD was mean ± SD =−0.4 ± 7.8%, for trochanter 0.6 ± 8.1%, and for the Ward's triangle 1.3 ± 9.7%. Both paired difference and ratio of asymmetry between BMDd and BMDn were approximately normally distributed, with a mean ± 2 SD ranging from −0.126 to 0.122 g/cm² for paired difference and −16.0% to 15.2% for the ratio of asymmetry in the femoral neck. These data revealed that dominance had little effect on the proximal femur BMDs. However, the wide range of paired difference and ratio of asymmetry of the proximal femur BMD in the normal individuals should be considered in the interpretation of the proximal femoral BMD. Received: 26 July 1996 / Accepted: 23 April 1997     

An Investigation of the Diagnostic Value of Bilateral Femoral Neck Bone Mineral Density Measurements

This paper describes a study to assess the clinical value of bilateral femoral neck bone mineral density (BMD) measurements. Although a range of factors will determine clinical decisions, the classification of the site with the lowest T-score is likely to have significant bearing on the management of a patient. While it is common practice to measure BMD at the lumbar spine and a single neck of femur, knowledge of the BMD of the second femur may also be of diagnostic value. Using dual-energy X-ray absorptiometry, BMD of the lumbar spine and right and left femoral neck was measured in a group of 2372 white, Caucasian women (mean age ± SD, 56.6 ±13.9 years) routinely referred for bone densitometry. Analysis of the measurements showed a significant (p= 0.02) but small difference between the mean BMD of the right (0.840 ± 0.152 g/cm²) and left (0.837 ± 0.150 g/cm²) femoral neck. Further investigation of femur scans revealed 79 (3.3%) patients in whom one side was osteoporotic while the other side and spine were normal or osteopenic using the World Health Organization diagnostic criteria in combination with manufacturer”s reference data. Patients in whom the femoral neck BMD measurements differed by less than the precision error of the system were then excluded. This left only 51 (2.2%) patients, that is 29 (1.2%) for right femur and spine scan and 22 (0.9%) for left femur and spine scan, in whom knowledge of both femoral neck BMD measurements could have altered the classification of the lowest site assessed to osteoporotic. These data suggest that there is only a small benefit from performing bilateral femoral neck BMD measurements. Since BMD measurements are only one of a range of factors considered as part of a patient”s management, it is suggested that the extra time, cost and radiation dose associated with measurement of the second femur may not be justified. Received: 28 October 1999 / Accepted: 2 February 2000     

Bone Mineral Density and Bone Turnover in Patients with Knee Osteoarthritis Compared with Generalized Osteoarthritis

The aim of this study was to investigate bone mineral density (BMD) and bone turnover in patients with primary knee osteoarthritis (KOA) and to compare them with generalized OA (GOA) and nonGOA patients. A total of 88 postmenopausal primary KOA patients were studied. OA was graded by using knee radiographs. BMD of the lumber spine, femur, and radius, and biochemical markers of bone turnover, pyridinoline (Pyr), deoxypyridinoline (Dpyr), CTx, and osteocalcin were compared among each grade. BMD was also compared with 88 normal controls who were age and weight-matched. In 88 KOA patients, 56 were divided into 28 GOA and 28 non-GOA groups by grading hand radiographs. BMD and biochemical markers were compared between GOA and non-GOA. KOA patients had higher BMD at several skeletal sites compared with age- and weight-matched normals. A significant difference of BMD between each grade was observed between grades 0–1 and 3 (0.774 ± 0.143 versus 0.940 ± 0.185 g/cm², P < 0.001), grades 2 and 3 (0.781 ± 0.125 versus 0.940 ± 0.185 g/cm², P < 0.01) in the spine, and between grades 0–1 and 3 (0.505 ± 0.100 versus 0.564 ± 0.127 g/cm², P < 0.05) in the trochanter. A significant difference of biochemical bone markers was observed between grades 0–1 and 3 (P < 0.05) and between grades 2 and 3 (P < 0.05) in Pyr and grades 0–1 and 3 (P < 0.05) and between grades 1 and 4 (P < 0.05) in Dpyr, but not in osteocalcin and CTx. GOA patients had higher BMD of the spine (0.902 ± 0.175 versus 0.747 ± 0.138 g/cm², P < 0.01), trochanter (0.535 ± 0.107 versus 0.480 ± 0.107 g/cm², P < 0.05), and one-third of the radius (0.526 ± 0.068 versus 0.472 ± 0.089 g/cm², P < 0.05) and had significantly higher biochemical markers in Pyr and Dpyr than non-GOA patients. It is concluded that KOA patients had higher BMD at several skeletal sites. Biochemical bone markers were influenced by some degree of cartilage damage in OA patients. This tendency was stronger in GOA patients than in non-GOA patients. Received: 12 February 1999 / Accepted: 2 November 1999     

Evaluation of dual-energy X-ray absorptiometry bone mineral measurement—comparison of a single-beam and fan-beam design: The effect of osteophytic calcification on spine bone mineral density

Dual energy X-ray absorptiometry (DXA) using a single-beam (SB) design is a well-established procedure for measuring bone mineral area density (BMD). Recently, fan beam (FB) techniques have become available to measure BMD. We evaluated the QDR1000 and QDR2000 densitometers with regard to precision and cross-compared values using single beam (SB) and FB techniques. To study the effect of osteoarthritic changes on bone measurement (BMC in g) and bone mineral area density (BMD in g/cm²), both parameters were measured in patients with and without osteophytic calcifications (OC) of the lumbar spine. Precision errors for BMD in vitro over 1 and 6 months using the QDR2000 were 0.4% and 0.6% for SB and 0.5% and 0.7% for the three FB modes. For QDR1000 only SB is available. Using this scan mode, the BMD difference (=0.1%) in vitro between QDR1000 and QDR2000 was not significant. The short-term (same day) reproducibility of BMD in vivo was 0.85% for SB mode and 1.1% for FB scan mode (n=33). The midterm (1 month) precision errors were 0.9% for SB and 1.5% for FB (n=11). The spine BMD of 751 patients from our outpatient clinic and department of rheumatology was 1.7% lower with FB than with SB (0.878±0.137 versus 0.888±0.146 g/cm²). Lower (1.8%) BMD values were also found in the hip with FB compared to SB (0.805±0.111 versus 0.821±0.111 g/cm²). There was a highly significant (P<0.00001) correlation between SB and FB on the spine (r =0.99) and hip (r=0.98) using the QDR2000. Correlations found QDR1000 and QDR2000 were lower on the spine (r=0.97) hip (r=0.93). In contrast to hip BMD, spine BMD was significantly higher in women (n=78) with OC (FB: 0.894±0.134 g/cm², SB: 0.900±0.140 g/cm²) than in normals (n=148) (FB: 0.844±0.130 g/cm², SB: 0.865±0.140 mals (n=148) (FB: 0.844±0.130 g/cm², SB: 0.865±0.140 g/cm²) (P<0.05). The FB mode provides reproducible data in vitro and in vivo, though not as precise as SB. FB results in vivo are 1–2% lower than FB results, even with identical results in vitro. Women with OC present with higher BMD values in spine scans than normals.     

Ambulatory level and asymmetrical weight bearing after stroke affects bone loss in the upper and lower part of the femoral neck differently: bone adaptation after decreased mechanical loading

The aim of this 1-year prospective study of acute stroke patients was to determine the effects of walking and asymmetrical weight bearing on the loss of bone mineral in the upper and lower femoral neck. Forty patients were followed. Eight remained unable to walk, whereas 32 relearned to walk independently within 7 months (12 shortly after the stroke, 15 by 2 months, 5 by 7 months). Bone mineral density (BMD) was measured in the proximal femur within the first week after stroke and 1 year later; regional BMD changes were computed for the lower and upper femoral neck. The lower part of the femoral neck is mainly influenced by compressive stresses of the hip, the upper part by tensile stresses during walking. When comparing mean BMD loss in groups of patients according to when they relearned to walk, a statistically significant trend in BMD loss was found in the lower femoral neck on both the paretic and nonparetic sides (p < 0.01 and p = 0.01, respectively), whereas, for the upper femoral neck, no significant trend was seen (p >/= 0.1). In addition, the body weight distribution during standing was assessed by use of a force-plate in 38 patients who could stand independently at the 7 month evaluation. The only significant correlation between changes in BMD and asymmetrical weight bearing was found in the lower femoral neck on the paretic side (r = 0.6, p < 0.001). In conclusion, this study shows that the reduction in BMD in the femoral neck occurs mainly in the lower part of the neck and on the paretic side. The BMD loss depended on when or if the patients relearned to walk, but also on the amount of body weight born on the paretic leg. Thus, measuring the lower part of the femoral neck gives a better estimate of the impact of gait and weight bearing than measuring the total femoral neck.     

Effect of Lifelong Nicotine Inhalation on Bone Mass and Mechanical Properties in Female Rat Femurs

As tobacco smoking has been identified as a risk factor in the development of osteoporosis, possible deleterious effects of nicotine inhalation on bone mineral density (BMD) and mechanical properties of the femur in female rats were studied. Female Sprague Dawley rats were exposed to nicotine vapour 20 hours a day 5 days a week for 2 years. The nicotine concentration in the inhaled air was kept at a level, giving a plasma nicotine concentration exceeding that of heavy smokers. Throughout the study, the nicotine-exposed rats weighed approximately 10% less than the control rats. At the end of the study the rats were anesthesized and blood was collected by heart puncture for determination of nicotine in plasma. Both femurs were resected and scanned by dual X-ray absorptiometry (DXA). There was no difference in BMD between control rats (n = 7) and nicotine-exposed rats (n = 23) (mean 0.216 ± 0.021 g/cm² and 0.210 ± 0.014 g/cm², respectively (P= 0.19)). The left femur was used for mechanical testing of the shaft and the neck. No significant difference could be demonstrated in ultimate bending moment, ultimate energy absorbtion, stiffness, or deflection between the two groups. In conclusion, no negative effects of nicotine inhalation on the femurs of female rats were found. Received: 26 December 1997 / Accepted: 28 January 1999     

Impact of Detraining on Bone Loss in Former Collegiate Female Gymnasts

Undesirable changes in health-related parameters are thought to occur in retiring female athletes, but this has not been examined in longitudinal studies. The purpose of this study was to examine longitudinal changes in bone mineral density (BMD), body composition, and dietary intake in gymnasts and controls. Nonathletic, college-age women (n = 9) were selected as a control group for comparison to the gymnasts (n = 10). Initial BMDs for the gymnasts were determined by using dual energy X-ray absorptiometry (Lunar, DPX) at the beginning of their final competitive year. Initial BMDs for the controls were measured during a similar time-frame. Follow-up measurements were made at least 1-year after the initial measurement. Gymnasts had significantly greater BMD of the femoral neck (1.262 versus 1.058 g/cm², respectively), Wards triangle (1.230 versus 1.008 g/cm²), greater trochanter (1002 versus 0.822 g/cm²), and total body (1.232 versus 1.145 g/cm²) than controls while still competing (P < .05). Following retirement from competition, (mean years of retirement, 4 years), BMD of the gymnasts remained significantly greater than controls at total body, femoral neck, trochanter, and Wards triangle (P < .05). Significant declines in femoral neck, Wards triangle, and greater trochanter BMD were found in both gymnasts and controls (0.72% to 1.9% per year), but only gymnasts had a significant decline at the lumbar spine (0.87% per year). In conclusion, BMD changes in former gymnasts appear to be site-specific, and gymnasts continue to have greater proximal femur BMD than controls, despite their decreased exercise, which may help postpone or prevent osteoporosis later in life.     

Precision of dual-photon absorptiometry

Summary Precision of dual-photon absorptiometry (DPA) measurements was determined in a lumbar spine phantom and in humans. Approximately half of the measurements were made before and half after a¹⁵³gadolinium source change. The phantom was measured with different amounts of acrylic, which simulates human soft tissue, in order to evaluate the influence of body thickness on bone mineral density (BMD). Results of scans analyzed with two software versions from Lunar Radiation Corp., the widely used 08B and a prototype 08C, are compared. DPA with a cold source significantly overestimated BMD in the phantom in the presence of large amounts (more than 25 cm) of soft tissue equivalent with version 08B but not with the newer version 08C. Similiarly, in nine subjects, there was a significant decrease in spine BMD after a source change when scans were analyzed with version 08B (mean difference 0.026 g/cm²,P=0.002) but not with 08C (0.01 g/cm²,P=0.234). No systematic effect of source change on femoral BMD measurements was observed. The SD of the mean difference of two measurements of the nine subjects was 0.019 g/cm² (1.6% of the mean value) for the spine with software version 08B and 0.024 g/cm² (2.0%) with version 08C, 0.03 g/cm² (3.3%) for the femur neck, 0.03 g/cm² (4.0%) for the greater trochanter, and 0.04 g/cm² (4.9%) for Ward's triangle region of the proximal femur. The spine phanton was scanned on two other commercial bone densitometers in order to assess inter-instrument variation. Phantom measurements of L2-4 BMD made on two Lunar Radiation Corp model DP3 scanners which differed by 2% were 10 and 12% higher than those with a Norland Corp. model 2600 scanner.     

Low bone mineral density in adults with previous hypothalamic-pituitary tumors: Correlations with serum growth hormone responses to GH-releasing hormone,insulin-like growth factor I,and IGF binding protein 3

Summary The adverse consequences of growth hormone (GH) deficiency (GHD) on bone growth in children is well described. Whether adult GHD is associated with bone loss is unknown. We evaluated 14 patients with hypothalamicpituitary tumors (HPT) acquired during adulthood (5 men, 9 women; age=48.1±4.6 years; BMI=28.8±1.7) and 14 age-, sex-, and weight-matched controls. Nine HPT patients were receiving gonadal steroid replacement therapy for a mean of 11 years. All subjects had basal IGF-I and IGFBP-3 levels prior to testing with GH-releasing hormone [1 g/kg IV bolus; responses expressed as maximum percentage increase above baseline (PERGH)]. Bone mineral density (BMD) of the spine, hip, and total body were measured by dual-energy X-ray absorptiometry. Mean BMD Z-scores of the HPT patients were significantly lower in the femoral neck, Ward's triangle, and trochanter than in controls (all P<0.05). Mean total body BMD (g/cm²) was also lower in the patient group (1.04±0.03 versus 1.13±0.03, P<0.05). For the subgroup of HPT patients receiving conventional gonadal steroids, mean BMD Z-scores of the lumbar spine also were significantly lower than controls (-1.84±0.43 versus -0.57±0.46, P<0.05). PERGH and IGF-l were correlated with Z-scores of the femoral neck (r=0.47, P<0.01; r=0.45, P<0.01) and Ward's triangle (r=0.47, P<0.01; r=0.41, P<0.05). These results indicate that adults with previous HPTs have significantly lower spine and hip BMD compared with healthy controls, regardless of gonadal steroid therapy, and that this premature bone loss is associated with relative GHD. IGF-I and PERGH measurements might be useful markers to identify such patients at risk for reduced BMD.     

Progressive Hemiosteoporosis on the Paretic Side and Increased Bone Mineral Density in the Nonparetic Arm the First Year after Severe Stroke

Fractures are a common and serious complication after stroke and the risk of hip fractures among stroke patients is 2 to 4 times greater than among other elderly people. The aim of this study was to investigate prospectively the change in bone mineral density (BMD) after severe stroke and to study the association between motor impairment, disability and the development of hemiosteoporosis. The study comprised 24 stroke patients, with no persistent paresis from previous strokes or previous osteoporotic fractures, included 1 month after stroke onset. BMD, motor function, ambulation and activities of daily living (ADL) were assessed at 1, 4, 7 and 12 months after stroke onset. At inclusion, the patients’ BMD was normal for their age. During the study, there was a significant loss of BMD in the total body (−2.0%; p<0.05), but not in the head or spine. BMD differed significantly between the paretic and the non-paretic arm at inclusion (−4.8%; p<0.001). Decrease in BMD was most pronounced in the affected humerus (−17.4%; p<0.001) and proximal femur (−12.2%; p<0.01). BMD decreased significantly in both lower extremities during follow-up, but the losses were more pronounced on the paretic side (p<0.01). In the nonaffected ultradistal radius there was a significant increase in BMD from inclusion to the end of the study (+5.8%; p<0.01). There was no pattern in the bone losses correlating with presumptive risk factors for hemiosteoporosis such as motor function, ability to perform ADL or ambulation. Two patients had fractures at follow-up, both on the paretic side. Loss of bone mineral density in the paretic extremities is thus pronounced and progressive during the first year after stroke, indicating that loss of BMD is probably an important risk factor for post-stroke fractures. Surprisingly, BMD in the nonaffected arm increased significantly during the first year after stroke, most likely due to increased physical activity, and perhaps a redistribution of bone minerals from the paretic extremities. Received: 13 January 1998 / Accepted: 24 July 1998     

Femoral and spinal bone mineral density in Japanese osteoporotics with hip fracture

In the present study, bone mineral density (BMD) of femoral neck and lumbar spine was compared between 38 Japanese female patients with hip fracture (age 63–89 years, mean±SD 76±7 years) and 162 age-matched female controls (age 62–90 years, mean±SD 75±7 years). BMD was measured in the femoral neck and lumbar spine (L2–4) using dual-photon absorptiometry (Norland model 2600). BMD values of femoral neck as well as lumbar spine were significantly lower in patients with hip fracture than in controls (0.504±0.097 v 0.597±0.101,p<0.01, for femoral neck; 0.661±0.146 v 0.720±0.128,p<0.05, for lumbar spine). Patients with hip fracture and controls were stratified according to their BMD levels at two measuring sites, and the ratio of the number of patients and controls at each BMD level was calculated as an indicator of fracture rate. This ratio showed an exponential increase as the femoral neck BMD declined, but only a gradual increase as the lumbar spine BMD declined. Specificity-sensitivity analysis revealed that BMD values of 0.59 and 0.54 g/cm² at the femoral neck provided a specificity of 52% and 68% with a sensitivity of 90% and 75%, respectively. These findings suggest that Japanese patients with hip fracture are more osteoporotic than age-matched controls and that the selective measurement of femoral neck would be useful for predicting the risk of hip fracture.     

Ultrasound and X-ray-Based Bone Densitometry in Patients with Anorexia Nervosa

In 20 patients (mean age 23 ± 5 years) with anorexia nervosa (AN), bone mass was evaluated by broadband ultrasound attenuation (BUA) of the calcaneus, peripheral quantitative computed tomography (pQCT) of the distal radius, and dual X-ray absorptiometry (DXA) of the lumbar spine and the hip. Compared with 20 age- and sex- matched healthy controls, patients with AN showed marked osteopenia at all measuring sites. Values of BUA (33.0 ± 9dB/MHz vs. 51.0 ± 5.7 dB/MHz; P < 0.0001) and of BMD of all regions of the hip (e.g., femoral neck: 0.71 ± 0.13 g/cm² versus 0.89 ± 0.07 g/cm²; P < 0.001), lumbar spine (0.82 ± 0.15 g/cm² versus 1.24 ± 0.06 g/cm²; P < 0.003) and total BMD of the peripheral radius (303.2 ± 75 g/cm³ versus 369.4 ± 53.2 g/cm³, P < 0.001) were significantly reduced. Calculating a Z-score we found the most prominent differences between AN and controls by BUA of the calcaneus (−3.2 ± 1.6), followed by DXA at the lumbar spine (−2.9 ± 2.2) and the hip (femoral neck −2.1 ± 1.7) and by pQCT at the distal radius (total BMD −1.2 ± 2.0). There were highly significant correlations between BUA of the calcaneus and BMD of the femoral neck (r = 0.78, P < 0.0001) and lumbar spine (r = 0.75, P < 0.0001) as well as between BMD values of the femoral neck and lumbar spine (r = 0.95; P < 0.0001). In addition, there were significant correlations (P < 0.001) between body mass index (BMI) and the three different measuring sites and between the duration of the disease and BUA (r = 0.5, P < 0.05). Our data suggest that BUA of the calcaneus is a valuable tool in the management of osteoporosis. Being a fast, radiation-free investigation method of good acceptance, it may be well suited for an assessment of the skeletal status in patients with AN. Received: 14 October 1998 / Accepted: 10 December 1999