Correlation of mechanical properties of vertebral trabecular bone with equivalent mineral density as measured by computed tomography

We tried to determine whether mineral-equivalent measurements that were obtained using computed tomography could be used to predict the mechanical properties of vertebral trabecular bone. Vertebral bodies that had been obtained during routine autopsy were evaluated by computed tomography. The mechanical properties of the vertebral trabecular bone were determined by subjecting cylindrical specimens to simple compression until failure occurred. The ultimate strength and elastic modulus were determined from load time curves, using constant displacement rate loading. Atomic absorption spectrophotometry was used to determine the weight per cent calcium of each specimen, and quantitative light microscopy was used to determine area fraction bone. Significant positive correlations were found between the observed mechanical properties of the trabecular bone and the equivalent mineral density as measured by computed tomography. Compressive strength (r = 0.720), elastic modulus (r = 0.574), trabecular calcium density (r = 0.780), and area fraction bone (r = 0.579) were all correlated with the equivalent mineral density.     

Influence of orthogonal overload on human vertebral trabecular bone mechanical properties.

The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. Results suggest that the trabecular structure has properties that act to minimize the decrease of apparent toughness transverse to the primary loading direction. INTRODUCTION: The maintenance of mechanical integrity and function of trabecular structure after overload remains largely unexplored. Whereas a number of studies have focused on addressing the question by testing the principal anatomical loading direction, the mechanical anisotropy has been overlooked. The aim of this study was to investigate the effects of overload in orthogonal directions on longitudinal and transverse mechanical integrity in human vertebral trabecular bone. MATERIALS AND METHODS: T(12)/L(1) vertebral bodies from five cases and L(4)/L(5) vertebral bodies from seven cases were retrieved at autopsy. A cube of trabecular bone was cut from the centrum of each vertebral body and imaged by microCT. Cubes from each T(12)/L(1) and L(4)/L(5) pairs were assigned to either superoinferior (SI) or anteroposterior (AP) mechanical testing groups. All samples were mechanically tested to 10% apparent strain by uniaxial compression according to their SI or AP allocation. To elucidate the extent to which overload in orthogonal directions affects the mechanical integrity of the trabecular structure, samples were retested (after initial uniaxial compression) in their orthogonal direction. After mechanical testing in each direction, apparent ultimate failure stresses (UFS), apparent elastic moduli (E), and apparent toughness moduli (u) were computed. RESULTS: Significant differences in mechanical properties were found between SI and AP directions in both first and second overload tests. Mechanical anisotropy far exceeded differences resulting from overloading the structure in the orthogonal direction. No significant differences were found in mean UFS and mean u for the first or second overload tests. A significant decrease of 35% was identified in mean E for cubes overloaded in the SI direction and then overloaded in the AP direction. CONCLUSIONS: Observed differences in the mechanics of trabecular structure after overload suggests that the trabecular structure has properties that act to minimize loss of apparent toughness, perhaps through energy dissipating sacrificial structures transverse to the primary loading direction.     

Quantitative computed tomography estimates of the mechanical properties of human vertebral trabecular bone.

The objective of this study was to report our quantitative computed tomography (QCT) density-mechanical property regressions for trabecular bone for use in biomechanical modelling of the human spine. Cylindrical specimens of human vertebral trabecular bone (from T10 to L4) were cored from 32 cadavers (mean +/- SD age = 70.1 +/- 16.8; 13 females, 19 males) and scanned using QCT. Mechanical tests were conducted using a protocol that minimized end-artifacts over the apparent density range tested (0.09-0.38 g/cm3). To account for the presence of multiple specimens per donor in this data set, donor was treated as a random effect in the regression model. Mean modulus (319 +/- 189 MPa) was higher and mean yield strain (0.78 +/- 0.06%) was lower than typical values reported previously due to minimization of the end-artifact errors. QCT density showed a strong positive correlation with modulus (n = 76) and yield stress (r2 = 0.90-0.95, n = 53, p < 0.001). There was a weak positive linear correlation with yield strain (r2 = 0.58, n = 53, p = 0.07). Prediction errors, incurred when estimating modulus or strength for specimens from a new donor, were 30-36% of the mean values of these properties. Direct QCT density-mechanical property regressions gave more precise predictions of mechanical properties than if physically measured wet apparent density was used as an intermediate variable to predict mechanical properties from QCT density. Use of these QCT density-mechanical property regressions should improve the fidelity of QCT-based biomechanical models of the human spine for whole bone and bone-implant analyses.     

Factors influencing vertebral bone density after renal transplantation

To improve our understanding of the mechanisms underlying osteoporosis following renal transplantation, we compared bone mineral density (BMD) in 158 transplant recipients and in 293 patients undergoing maintenance hemodialysis with age- and sex- matched normal controls. Observations in graft recipients were made up to several years following transplantation. Dual-energy X-ray absorptiometry was used to measure BMD. Correlations with clinical variables including serum concentration of parathyroid hormone (PTH) and steroid therapy were evaluated. Lumbar BMD was lower in transplant patients than in dialysis patients at all ages, and continued to decrease with increasing interval posttransplant until the second year after transplantation. Persistent hyperparathyroidism and daily prednisolone dosage were both associated with decreased BMD. Age and creatinine clearance were independent long-term predictors of BMD by multiple regression analysis. Treatment of renal graft recipients with calcium and vitamin D supplements or calcitonin may be indicated in the early months after transplantation.     

Reduced vertebral bone density in hypercalciuric nephrolithiasis.

Dual-energy x-ray absorptiometry and single-photon absorptiometry were used to determine bone density at the lumbar spine and radial shaft in 62 patients with absorptive hypercalciuria, 27 patients with fasting hypercalciuria, and 31 nonhypercalciuric stone formers. Lumbar bone density was significantly lower in patients with absorptive (-10%) as well as in those with fasting hypercalciuria (-12%), with 74 and 92% of patients displaying values below the normal mean, whereas only 48% of the nonhypercalciuric stone formers had bone density values below the normal mean. In contrast, radial bone density was similar in all three groups of renal stone formers investigated. The comparison of urinary chemistry in patients with absorptive hypercalciuria and low normal bone density compared to those with high normal bone density showed a significantly increased 24 h urinary calcium excretion on random diet and a trend toward a higher 24 h urinary uric acid excretion and a higher body mass index in patients with low normal bone density. Moreover, among the patients with absorptive hypercalciuria we found a statistically significant correlation between the spinal bone density and the 24 h sodium and sulfate excretion and the urinary pH. These results gave evidence for an additional role of environmental factors (sodium and animal proteins) in the pathogenesis of bone loss in absorptive hypercalciuria. In conclusion, our data suggest an osteopenia of trabecular-rich bone tissues in patients with fasting and absorptive hypercalciurias.     

The relationship between phalangeal bone density and vertebral deformities

Radiographic absorptiometry (RA) of the phalanges is a convenient and reliable technique for measuring bone mineral density (BMD). It needs only a radiograph of the hand, which can be sent for evaluation to a central facility, whereas other techniques require specialized equipment. We assessed the relationship between RA measurements and the presence of vertebral deformities in a population-based cohort of postmenopausal women, and to compare the results with simultaneously obtained BMD of the hip by dual-energy X-ray absorptiometry (DXA). A total of 389 women aged 55–84 (mean age 67.2 years, SD 8.7) were randomly selected from a large general practice. RA, DXA of the hip, and vertebral deformities in the lateral spine X-rays by vertebral morphometry were assessed. Thirty-eight women (9.8%) had severe (grade II) vertebral deformities, and their BMD at the phalanges and femoral neck was significantly lower than that of women without severe vertebral deformities. Odds ratios for the presence of severe vertebral deformities of 1.5 (95% CI: 1.1–2.1) for RA and 1.3 (95% CI: 0.9–1.9) for DXA, together with similar receiver operating characteristics curves, were found using age-adjusted logistic regression. Phalangeal BMD is related to vertebral deformities at least as closely as BMD of the femoral neck BMD. RA may therefore help to evaluate fracture risk, especially if no DXA equipment is available. Received: 21 July 1998 / Accepted: 1 July 1999     

Relationship of age to bone microstructure independent of areal bone mineral density

Previous studies using dual-energy X-ray absorptiometry (DXA) have demonstrated that age is a major predictor of bone fragility and fracture risk independent of areal bone mineral density (aBMD). Although this aBMD-independent effect of age has been attributed to poor bone "quality," the structural basis for this remains unclear. Because high-resolution peripheral quantitative computed tomography (HRpQCT) can assess bone microarchitecture, we matched younger and older subjects for aBMD at the ultradistal radius and assessed for possible differences in trabecular or cortical microstructure by HRpQCT. From an age-stratified, random sample of community adults, 44 women aged <50 years (mean age 41.0 years) were matched to 44 women aged ≥50 years (mean age 62.7 years) by ultradistal radius aBMD (mean ± SEM, younger and older aBMD 0.475 ± 0.011 and 0.472 ± 0.011 g/cm2, respectively), and 57 men aged <50 years (mean age 41.3 years) were matched to 57 men aged ≥50 years (mean age 68.1 years; younger and older aBMD both 0.571 ± 0.008 g/cm2). In these matched subjects, there were no sex-specific differences in trabecular microstructural parameters. However, significant differences were noted in cortical microstructure (all p < 0.05): Older women and men had increased cortical porosity (by 91% and 56%, respectively), total cortical pore volume (by 77% and 61%, respectively), and mean cortical pore diameter (by 9% and 8%, respectively) compared with younger subjects. These findings indicate that younger and older women and men matched for DXA aBMD have similar trabecular microarchitecture but clearly different cortical microstructure, at least at an appendicular site represented by the radius. Further studies are needed to define the extent to which this deterioration in cortical microstructure contributes to the aBMD-independent effect of age on bone fragility and fracture risk at the distal radius and other sites of osteoporotic fractures.     

骨质疏松椎体变形与骨密度和骨代谢水平的相关性研究

目的探讨骨质疏松患者椎体变形与骨密度(BMD)和骨代谢水平的相关性。方法以GENANT半定量法为标准,按照胸腰椎椎体不同变形程度将883例骨质疏松患者分为GENANT 0级、0.5级、1级、2级、3级共5组,测量各组的BMD、体质量指数以及Ⅰ型前胶原氨基端前肽(PINP)、β胶原降解产物β-crosslaps、N端中分子片段骨钙素(N-MID)等骨代谢指标,分析骨质疏松椎体变形程度与上述指标的相关关系,统计骨质疏松患者年龄、性别以及上述指标与骨折风险的相关性。结果椎体变形等级与BMD、体质量指数呈负相关(P0.05),与骨代谢指标呈正相关(P0.05);椎体变形GENANT 3级骨质疏松患者BMD、体质量指数低于其他GENANT等级,GENANT 1~3级患者骨代谢水平高于GENANT 0级、0.5级,GENANT 0级患者骨代谢水平最低(P0.05)。骨质疏松性椎体骨折女性患者多于男性,其发生随年龄增加而呈现增大趋势;80岁以上人群BMD、体质量指数和骨代谢水平均低于其他年龄组,且存在椎体变形的比例最高(P0.05)。结论骨质疏松患者的椎体变形与BMD、体质量指数以及PINP、β-crosslaps、N-MID等骨代谢指标有一定的相关关系;综合运用性别、年龄、BMD、体质量指数和骨代谢指标能提高骨质疏松椎体变形的诊断准确率,对预测骨质疏松患者椎体变形程度和骨折风险具有重要的指导意义。     

Poroelastic properties of bovine vertebral trabecular bone.

The theory of poroelasticity has been used to study bone mechanics without directly measuring poroelastic properties. In this study, we developed an experimental protocol and measured the poroelastic properties of bovine vertebral trabecular bone. Mean (+/-SD) values for drained shear modulus, drained Poisson's ratio, undrained Poisson's ratio, Skempton's coefficient, and permeability coefficient were, respectively, 90.85 (+/-59.59) MPa and 0.242 (+/-0.099), 0.399 (+/-0.083), 0.851 (+/-0.144), and 16.31 (+/-8.02) x 10(-8) m2/Pa/sec, respectively. The experimental protocol can be used generally for the measurement of poroelastic properties of bone when cylindrical specimens are available. Measured poroelastic properties can be used directly or converted to Biot's coefficient and modulus, without assuming the incompressibility of solid and fluid constituents, for the poroelastic modeling of bone.     

Effect of estrogen and calcitonin on vertebral bone density and vertebral height in osteoporotic women

Estrogen and calcitonin increase bone density of osteoporotic women, particularly on the axial skeleton. To verify whether the effect of these drugs might in part be biased by spurious increases in bone density due to radiologically irrelevant microfractures, and consequent subtle decreases in vertebral height, we followed the changes in vertebral bone density (VBD), assessed by quantitative computed tomography, in relation to vertebral height (VH) in 60 osteoporotic women. VH was measured as the sum of anterior, central and posterior heights of L1–L3 vertebral bodies on lateral radiographs. Patients received either salmon calcitonin (sCT: 50 IU subcutaneously three times per week,n=18), hormonal replacement therapy (HRT: conjugated estrogen 0.625 mg/day, days 1–25, plus medroxyprogesterone acetate 10 mg/day, days 16–25 of each month;n=21) or calcium alone (Ca: 1000 mg/day,n=21). After 1 year, VBD increased in the HRT group (+5.0 ± 1.9%,p=0.010), did not change significantly in the sCT group (+3.3 ± 2.3%,p=0.167), and decreased by 6.1 ± 1.0% (p<0.001) in the Ca group. By analysis of variance, the changes induced by HRT and sCT were significantly different from those observed in the Ca group (F=7.982,p<0.001). VH decreased slightly in all three subsets of patients (–0.9 ± 0.5% in sCT, –1.5 ± 0.3% in HRT, –0.1 ± 0.5% in Ca), but these changes were not significantly different between groups (F=2.545,p=0.081). Correcting for this height decrease by analysis of covariance did not affect the significant effect of sCT and HRT on VBD, compared with that of Ca (F=6.801,p=0.001). Furthermore, no correlation was found between changes in bone VBD and VH in any of the groups. These data indicate that microfractures do not significantly account for the increases in bone density during active treatment of osteoporosis with either estrogen or calcitonin.     

腰椎各椎体骨密度的分析

目的分析腰椎各椎体骨密度（ＢＭＤ）的差异。方法对１２１４例在我科进行骨密度检查的２０～８９岁人群,男性３９０例,女性８２４例,除外各种器质性内分泌、消化系统及肿瘤等疾病,用双能Ｘ线骨密度仪（ＤＥＸＡ）测量腰椎ＢＭＤ,通过计算机分析比较各椎体ＢＭＤ值的差异与相互关系,用ＥＸＣＥＬ软件做统计学分析,计数资料进行配对ｔ检验。结果ＢＭＤ值以Ｌ１最低,Ｌ４最高,Ｌ１－２与Ｌ２－４ＢＭＤ女性在４０岁以上有显著差异（Ｐ＜０．００１）,男性在６０岁以上（Ｐ＜０．０５）,８０岁以后无明显差异,女性５０岁以后骨丢失明显快于男性。结论腰椎各椎体ＢＭＤ存在差异,尤以女性明显,其差异与增龄造成的腰椎退行性变的干扰有关     

椎体成形术中椎体骨密度对骨水泥弥散体积的影响

目的:探讨椎体成形术中椎体骨密度对骨水泥弥散体积的影响。方法:18例胸腰椎压缩骨折患者,术前均行骨折椎体双能X线骨密度仪测定,根据WHO骨质疏松症诊断标准分为骨密度正常组(A组)、骨密度减低组(B组)及骨质疏松组(C组),每组6例,采用经伤椎单侧椎弓根行椎体成形术,术中注入相同状态和批次骨水泥2.5ml,术后采用64排CT扫描椎体,计算骨水泥注射体积及弥散体积。结果:所有患者均顺利完成手术并均成功注2.5ml骨水泥,CT计算骨水泥注射体积:A组2.460±0.116cm3,B组2.450±0.038cm3,C组2.457±0.037cm3;骨水泥在椎体中弥散体积:A组为6.717±1.127cm3,B组为5.650±0.669cm3,C组为4.617±0.542cm3。三组骨水泥弥散体积均大于同组注射体积(P<0.01);三组间骨水泥注射提及比较均无统计学差异(P>0.05)。弥散体积比较均有统计学差异(P<0.05),A组弥散体积最大。结论:椎体成形术中骨水泥弥散体积大于骨水泥注射体积;椎体骨密度与椎体内骨水泥弥散体积密切相关,骨密度越高,弥散体积越大。     

Relationship between phalangeal bone density and risk of vertebral fracture.

The aims of our study were to determine the relationship between bone mineral density (BMD) measurements of the phalanges obtained with the accuDEXA and recent vertebral fractures. To determine whether osteoarthritis of the hands affects phalangeal BMD measurements, and to illustrate the conversion of phalangeal BMD measurements to absolute fracture risk estimates for clinical application. The prospective Hawaii Osteoporosis Study began in 1981, and incident vertebral fractures were identified from serial radiographs obtained at approx 2-yr intervals. Vertebral fractures occurring between 1993 and 1994 and 1997 and 1998 were compared to phalangeal BMD measurements obtained in 1997-1998. A total of 199 women participated in this case-control study. The association of the phalangeal BMD measurements with vertebral fractures was examined in age-adjusted, logistic regression models. Results are expressed as odds ratios (ORs) per SD difference in the phalangeal BMD measurements. Osteoarthritis of the hands was graded according to the Kellgren-Lawrence scale. There were 34 incident fractures since the eighth examination in 1993-1994. For vertebral fractures, the OR per SD of phalangeal BMD was 1.5 (1.0-2.1). Phalangeal BMD was not influenced significantly by established osteoarthritis (p = 0.68). Phalangeal BMD measurements obtained with the accuDEXA device relate to recent vertebral fractures and can be used to identify women at high risk of fractures. The phalangeal BMD measurements obtained with this device are not significantly influenced by the presence of osteoarthritis of the hands.     

Cross calibrated standard values of vertebral bone mineral density in Japanese

The reference value of L2-4 bone mineral density (BMD) was calculated in Japanese population by using cross-calibration formulae among the different types of dual energy X-ray absorptiometry (DEXA) and dual photon absorptiometry (DPA). The scan data of lumbar spine were collected from 16 institutes equipped 3 types of DEXA and 3 types of DPA. After subtraction of inadequate scan data, a total of 1038 cases (376 males and 662 females) were accepted to be a representative “normal” population of Japanese. The L2-4 BMD values were adjusted to one equipment by using cross-calibration equations. There were significant decrease in L2-4 BMD in both sexes at age of seventies or more (9.5% decrease in males and 27.5% in females from the peak bone density).     

Comparison of the radiographic vertebral trabecular pattern with the vertebral fracture prevalence and spinal bone density

Spinal bone densitometry allows accurate and precise measurement of the severity of bone loss. Where densitometry is not yet available medical practitioners have to continue to rely on clinical radiography. Since the grey levels of the radiographic image are highly inaccurate we studied the radiographic vertebral trabecular pattern for its suitability as a semiquantitative assessment of vertebral bone loss. We defined four vertebral trabecular pattern indices (VTPI 4=normal, VTPI 1=severe bone loss) and tested these for correlations with the prevalence of vertebral fractures, and with spinal and hip bone mineral density measured by dual-energy X-ray absorptiometry (DXA). We found negative correlations between VTPI and the percentage of patients with vertebral fractures (p=0.0001), between VTPI and the number of vertebral fractures per patient (r=0.606,p=0.001) and between VTPI and the severity of vertebral fractures, and a positive correlation between VTPI and spinal (r ²=0.556,p=0.0001) and hip DXA values (r ²=0.315,p=0.0001). We conclude that the vertebral trabecular pattern index can be used to assess the severity of spinal bone loss when a bone densitometer is not available.     

Inhomogeneity of human vertebral cancellous bone: systematic density and structure patterns inside the vertebral body

In the spine, cancellous bone quality is usually assessed for the whole vertebral body in a transverse central slice. Correct identification and assessment of the weakest parts of the cancellous bone may lead to better prediction of fracture risk. The density and structural parameters were systematically investigated inside the thoracic (T-9), thoracolumbar (T12-L1), and lumbar (L-4) vertebral bodies of nine subjects. On both sides of the median sagittal plane, anterior and posterior 8.2 mm vertical cores were harvested in the thoracic vertebra. In the thoracolumbar and lumbar vertebrae, external samples were also cored. Peripheral quantitative computed tomographic (pQCT) density analysis of the 136 cores was performed at four different levels, from the lower to the upper endplate. The relatively thin slice thickness (300 microm) and small pixel size (70 microm x 70 microm) was considered sufficient to investigate the structural parameters on the four transverse slices and in the sagittal and coronal planes (total of 816 images). Using a constant threshold a binary image was generated and the morphometric data were extracted. The binary image was further skeletonized and classical strut analysis was performed. Cancellous bone density was 20% higher in the posterior cores than in the anterior and external cores. Moreover, clear vertical inhomogeneity was noted because the lowest half of the vertebral body presented lower density than the upper half (differences ranging from 25% to 15%). All structural parameters were strongly dependent on the location of the measurement. Structural differences between anterior, posterior, and external areas were mild and followed the density patterns. On the other hand, vertical inhomogeneity of the structural parameters was important. For example, in the thoracolumbar and lumbar vertebrae, the numbers of nodes or node-to-node struts were almost twofold higher in the inferior half than in the superior half (p < 0.01), whereas trabecular thickness and number of free-ends presented a center/close-to-endplate structural pattern, with central trabeculae being 15% thicker (p < 0.05) and presenting 30% fewer free-ends (p < 0.01) than the close-to-endplate ones. Variability of density and structural parameters was high and a substantial part of this variability could be explained by the place inside the vertebral body where the measurement was made. The weak part was not in the center of the body but in its upper half where the lower density did not seem to be compensated by a higher structural architecture. Further clinical investigation could enhance fracture prediction by tracking and focusing on the weakest part of the vertebral body.     

Water content measured by proton-deuteron exchange NMR predicts bone mineral density and mechanical properties.

NMR was used to measure matrix water content in normal and hypomineralized cortical bone. Water content showed an inverse relationship with mineral content, suggesting it could serve as a surrogate measure for the bone's degree of mineralization. INTRODUCTION: So far, true bone mineral density (DMB; degree of mineralization of bone) can not be measured nondestructively. MATERIALS AND METHODS: Here, a new technique combining 1H nuclear magnetic resonance (NMR) spectroscopy and deuterium isotope exchange was used to measure water content in cortical bone from two groups of rabbits: a control group and a group fed a low-phosphorus (P) diet to induce hypomineralization of the bone matrix. RESULTS: NMR-derived water content was higher in the P-depleted group and showed an inverse relationship with mineral content (measured gravimetrically and by 31p NMR). Hypomineralized bone was found to be weaker than normal bone as demonstrated by mechanical testing. More importantly, the data showed a strong inverse correlation between water content and bone mechanical properties, which indicates that water content could be predictive of the bone's mechanical competence. CONCLUSIONS: Water content could potentially serve as a surrogate measure for the bone's degree of mineralization, and this technique could be used to study other disorders of mineral homeostasis known to alter the mineralization state of the matrix. Although the method presented here is not suitable for in vivo measurements of bone water content, the authors have previously shown that 1H NMR images of bone can be acquired; thus, noninvasive quantification of bone water may be feasible.     

Fractures and vertebral bone mineral density in patients with renal osteodystrophy

We investigated the relationship of CT determined vertebral bone mineral density (BMD), type of renal osteodystrophy, N terminal PTH levels and fracture history in 31 dialysis patients. BMD for patients with bone biopsy documented osteitis fibrosa was 1.6 standard deviation (SD) above the normal value for age and sex matched controls, while those patients with low turnover osteodystrophy had a mean BMD 1.2 SD below normal (p less than 0.0001). Three patients with osteitis fibrosa who had previously been treated with prednisone had a low BMD (1.8 SD below normal, different than O, p = 0.0015). There was no correlation between BMD and time on dialysis (r = 0.1). An N terminal PTH level greater than 150 pg/ml was a sensitive (94%) and specific (100%) method of separating those patients with osteitis fibrosa from those with low turnover osteodystrophy, while BMD was much less useful in this differentiation. A low BMD was not predictive of fracture history but the type of renal osteodystrophy was. Patients with low turnover osteodystrophy had a fracture rate of 0.2 fractures/dialysis year in comparison to those with osteitis fibrosis who had 0.1 fractures/dialysis year. Patients with the former bone disease fractured mainly axial rather than appendicular bones in contrast to those patients with osteitis fibrosa. In conclusion we found that patients with osteitis fibrosa had increased BMD compared to normal while those with low turnover osteodystrophy had decreased BMD, but that the N terminal PTH level was a better predictor of the type of bone disease present than was BMD.     

Prevention of loss of vertebral bone density in heart transplant patients.

Seventy-six patients (63 men, 13 women) have been followed up by vertebral bone density (VBD) studies from 3 to 36 months. VBD was measured by single-energy computerized tomographic scan. Before transplantation, VBD was found to be lower than in age-matched controls (less than 40 years of age [group 1], 96% of controls: 40 through 49 years of age [group 2], 77%; 50 to 60 years of age [group 3], 87%; more than 60 years of age [group 4], 76%). After transplantation, despite oral calcium supplements, VBD fell further in all but two patients (97%), which was almost certainly related to maintenance steroid and cyclosporine therapy, and was most marked in the older groups (group 2, 67% compared with age-matched controls at 6 months; group 3, 60%; group 4, 50%). Intensive therapy with synthetic salmon calcitonin (in 29 of 76 patients [38%]), testosterone (in 33 of 63 men [52%]), or estrogen (in 12 of 13 women [92%]) limited, but did not totally prevent, further loss in VBD; in patients who had shown an approximate 45% loss of VBD from pretransplantation levels, further loss was reduced to between 4% and 10%. Five patients increased bone density after calcitonin therapy. Despite significantly reduced VBD in several older patients, minor vertebral bone compression developed in only one patient. We recommend that all patients undergoing heart transplantation, particularly those over the age of 50 years, should be followed by VBD studies, and therapy should be administered to prevent VBD loss.