Age, sex, and grip strength determine architectural bone parameters assessed by peripheral quantitative computed tomography (pQCT) at the human radius

The purpose of this study was to estimate the relation of some noninvasively derived mechanical characteristics of radial bone including architectural parameters for bone strength to grip strength and muscle cross-section. Sixty-three males between 21 and 78yr of age and 101 females between 18 and 80yr of age were measured at the nondominant forearm using peripheral quantitative computed tomography (pQCT). We assessed the integral bone mineral density (BMD(I)) and content (BMC(I)) by pQCT at the distal and at the mid-shaft radius. Integral bone area (Area(I)), cortical thickness (C-th), and a newly proposed index for bone strength; the stress-strain index (SSI) were also calculated. The dynamometrically measured maximum grip strength was taken as a mechanical loading parameter and muscle cross-section as a substitute for it. Sex, grip strength, BMC(I) and BMD(I) (distal radius) were identified in a multiple regression analysis to significantly predict bone strength as expressed by SSI, after adjusting for all other independent variables, including age and sex (p<0.0001). Grip strength was closest related to age, sex, BMD(I) and SSI(p) of the distal radius. The cross-sectional area of muscle was not significantly determining the grip strength within the analysis model. In conclusion, our results suggested that architectural parameters at the distal radius were better related to grip strength than to cross-sectional muscle area in both males and females. Maximum muscle strength as estimated by grip strength might be a stronger determinant of mechanical characteristics of bones as compared with cross-sectional muscle area.     

Bone adaptation to altered loading after spinal cord injury: a study of bone and muscle strength

Bone loss from the paralysed limbs after spinal cord injury (SCI) is well documented. Under physiological conditions, bones are adapted to forces which mainly emerge from muscle pull. After spinal cord injury (SCI), muscles can no longer contract voluntarily and are merely activated during spasms. Based on the Ashworth scale, previous research has suggested that these spasms may mitigate bone losses. We therefore wished to assess muscle forces after SCI with a more direct measure and compare it to measures of bone strength. We hypothesized that the bones in SCI patients would be in relation to the loss of muscle forces. Six male patients with SCI 6.4 (SD 4.3) years earlier and 6 age-matched, able-bodied control subjects were investigated. Bone scans from the right knee were obtained by pQCT. The knee extensor muscles were electrically stimulated via the femoral nerve, isometric knee extension torque was measured and patellar tendon force was estimated. Tendon force upon electrical stimulation in the SCI group was 75% lower than in the control subjects (p<0.01). Volumetric bone mineral density of the patella and of the proximal tibia epiphysis were 50% lower in the SCI group than in the control subjects (p<0.01). Cortical area was lower by 43% in the SCI patients at the proximal tibia metaphysis, and by 33% at the distal femur metaphysis. No group differences were found in volumetric cortical density. Close curvilinear relationships were found between stress and volumetric density for the tibia epiphysis (r(2)=0.90) and for the patella (r(2)=0.91). A weaker correlation with the tendon force was found for the cortical area of the proximal tibia metaphysis (r(2)=0.63), and none for the distal femur metaphysis. These data suggest that, under steady state conditions after SCI, epiphyseal bones are well adapted to the muscular forces. For the metaphysis of the long bones, such an adaptation appears to be less evident. The reason for this remains unclear.     

pQCT provides better prediction of canine femur breaking load than does DXA

Our study was designed to examine the validity of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) measurements as predictors of whole bone breaking strength in beagle femora. DXA was used to determine the bone mineral content, bone area, and 'areal' bone mineral density. PQCT was used to determine the cross-sectional moments of inertia, volumetric densities of the bone, and to calculate bone strength indices based on bone geometry and density. A three-point bending mechanical test was used to determine maximal load. Three variables from the pQCT data set explained 88% of the variance in maximal load, with the volumetric bone mineral density explaining 32% of the variance. The addition of the volumetric cortical density increased the adjusted r(2) to 0.601 (p=0.001) and the addition of an index created by multiplying volumetric cortical bone density by the maximum cross-sectional moment of inertia made further significant (p<0.001) improvements to an adjusted r(2) of 0.877. In comparison, when only the DXA variables were considered in a multiple regression model, areal bone mineral density was the only variable entered and explained only 51% (p<0.001) of the variance in maximal load. These results suggest that pQCT can better predict maximal load in whole beagle femora since pQCT provides information on the bone's architecture in addition to its volumetric density.     

Analysis of the independent power of age-related,anthropometric and mechanical factors as determinants of the structure of radius and tibia in normal adults. A pQCT study

To compare the independent influence of mechanical and non-mechanical factors on bone features, multiple regression analyses were performed between pQCT indicators of radius and tibia bone mass, mineralization, design and strength as determined variables, and age or time since menopause (TMP), body mass, bone length and regional muscles’ areas as selected determinant factors, in Caucasian, physically active, untrained healthy men and pre- and post-menopausal women. In men and pre-menopausal women, the strongest influences were exerted by muscle area on radial features and by both muscle area and bone length on the tibia. Only for women, was body mass a significant factor for tibia traits. In men and pre-menopausal women, mass/design/strength indicators depended more strongly on the selected determinants than the cortical vBMD did (p<0.01-0.001 vs n.s.), regardless of age. However, TMP was an additional factor for both bones (p<0.01-0.001). The selected mechanical factors (muscle size, bone lengths) were more relevant than age/TMP or body weight to the development of allometrically-related bone properties (mass/design/strength), yet not to bone tissue “quality” (cortical vBMD), suggesting a determinant, rather than determined role for cortical stiffness. While the mechanical impacts of muscles and bone levers on bone structure were comparable in men and pre-menopausal women, TMP exerted a stronger impact than allometric or mechanical factors on bone properties, including cortical vBMD.     

Peripheral quantitative computed tomography of the lower leg in children and adolescents: bone densities,cross-sectional sizes and muscle distribution reference data

Objectives:Peripheral quantitative computed tomography is utilised in increasing numbers of paediatric studies, however, very little is known about the reference limits for pQCT tibia measurements. The purpose of this study was to establish country-specific reference data for bone densities, cross-sectional sizes, strength and regional muscle distribution measured by pQCT in children and adolescents.Methods:Stratec XCT 2000L apparatus was used. The measurement sites were 4%, 14%, 38% and 66% of the tibia length. The study group consisted of 222 participants (103 girls) aged 4,3-19,4 yrs. ANCOVA was used to assess the main determinants of pQCT outcomes. The LMS method was used to fit the percentile curves for each outcomes.Results:Weight and age were the main determinants for most of the pQCT outcomes. Smoothed percentile curves were developed by age and by height for both sexes.Conclusion:In this study we present reference data for bone densities, cross-sectional size and strength as well as for regional muscle distribution measured by pQCT at certain sites of the lower leg to allow simple calculation of reliable Z scores.     

Hindlimb unloading has a greater effect on cortical compared with cancellous bone in mature female rats.

This study was designed to determine the effects of 28 days of hindlimb unloading (HU) on the mature female rat skeleton. In vivo proximal tibia bone mineral density and geometry of HU and cage control (CC) rats were measured with peripheral quantitative computed tomography (pQCT) on days 0 and 28. Postmortem pQCT, histomorphometry, and mechanical testing were performed on tibiae and femora. After 28 days, HU animals had significantly higher daily food consumption (+39%) and lower serum estradiol levels (-49%, P = 0.079) compared with CC. Proximal tibia bone mineral content and cortical bone area significantly declined over 28 days in HU animals (-4.0 and 4.8%, respectively), whereas total and cancellous bone mineral densities were unchanged. HU animals had lower cortical bone formation rates and mineralizing surface at tibial midshaft, whereas differences in similar properties were not detected in cancellous bone of the distal femur. These results suggest that cortical bone, rather than cancellous bone, is more prominently affected by unloading in skeletally mature retired breeder female rats.     

Case-control study of the muscular compartments and osseous strength in neurofibromatosis type 1 using peripheral quantitative computed tomography

Skeletal anomalies are observed in neurofibromatosis type 1 (NF1), but the pathogenesis is unknown. Given that muscle mass is important in the development of the strength of bone, peripheral quantitative computed tomography (pQCT) was utilized to compare measurements of muscle compartments between NF1 individuals and controls. Forty individuals with NF1 (age 5-18 years) were evaluated. Cross-sectional measurements, at the 66% tibial site, were obtained using pQCT (XCT-2000, Stratec) and variables were compared to controls without NF1 ((age 5-18 years, N=380) using analysis-of-covariance controlling for age, height, Tanner stage, and gender. The NF1 cohort showed decreased total cross-sectional area [p<0.001], decreased muscle plus bone cross-sectional area [p<0.001], decreased muscle cross-sectional area [p<0.001], and decreased Stress Strain Index [p=0.010]. These data indicate that NF1 individuals have decreased muscle cross-sectional area and decreased bone strength than individuals without NF1.     

Bone mineral density and microarchitecture in participants of a 105-day experiment in isolated environment

A study on the bone system state in healthy volunteers has been performed before and after 105-day experiment in hermetically isolated environment (the Mars-105 experiment) using dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). The values of bone mineral density (BMD), volumetric bone mineral density (VBMD), and bone structural characteristics of distal segments in radius and tibia have been evaluated. No significant DXA changes have been revealed in segments of skeleton critically important in terms of biomechanics. Microarchitectural deterioration (a decrease in the trabecula number and increase in the bone tissue heterogeneity) has been found using the pQCT technique in the radius of the majority of subjects. A VBMD decrease has been revealed for both cortical and trabecular bones in tibia, along with an unexpected trabecular bone improvement in the form of an increase in the trabecula quantity and decrease in bone tissue heterogeneity. Comprehensive studies, including estimation of projective and volumetric bone mineral densities (the bone mineral content) and bone structural characteristics (bone quality) are required to have a clear view on the changes in the bone system under the conditions of a simulation experiment.     

Reduced trabecular bone mineral density and cortical thickness accompanied by increased outer bone circumference in metacarpal bone of rheumatoid arthritis patients: a cross-sectional study

Introduction

The objective of this study was to assess three-dimensional bone geometry and density at the epiphysis and shaft of the third meta-carpal bone of rheumatoid arthritis (RA) patients in comparison to healthy controls with the novel method of peripheral quantitative computed tomography (pQCT).

Methods

PQCT scans were performed in 50 female RA patients and 100 healthy female controls at the distal epiphyses and shafts of the third metacarpal bone, the radius and the tibia. Reproducibility was determined by coefficient of varia-tion. Bone densitometric and geometric parameters were compared between the two groups and correlated to disease characteristics.

Results

Reproducibility of different pQCT parameters was between 0.7% and 2.5%. RA patients had 12% to 19% lower trabecular bone mineral density (BMD) (P ≤ 0.001) at the distal epiphyses of radius, tibia and metacarpal bone. At the shafts of these bones RA patients had 7% to 16% thinner cortices (P ≤ 0.03). Total cross-sectional area (CSA) at the metacarpal bone shaft of pa-tients was larger (between 5% and 7%, P < 0.02), and relative cortical area was reduced by 13%. Erosiveness by Ratingen score correlated negatively with tra-becular and total BMD at the epiphyses and shaft cortical thickness of all measured bones (P < 0.04).

Conclusions

Reduced trabecular BMD and thinner cortices at peripheral bones, and a greater bone shaft diameter at the metacarpal bone suggest RA spe-cific bone alterations. The proposed pQCT protocol is reliable and allows measuring juxta-articular trabecular BMD and shaft geometry at the metacarpal bone.     

How cancellous and cortical bones adapt to loading and growth hormone

There is great interest in the relationships between growth hormone (GH), muscle loading and bone, in part, because GH increases muscle mass which provides the largest signals that control bone modeling and remodeling. This study was designed to examine the effects of GH and muscle loading by exercise (EX) independently and in combination on bone and skeletal muscle. Thirteen-month-old female F344 rats were divided into 6 groups: Group 1, baseline controls (B); Group 2, agematched controls (C); Group 3, GH treated (2.5 mg rhGH/kg b. wt/day, 5 days per week); Group 4, voluntary wheel running exercise (EX); Group 5, GH+EX, and rats in Group 6 were food restricted (FR) to lower their body weight and examine the effects of decreased muscle load on bone. All animals, except the baseline controls, were sacrificed after 4.5 months. Growth hormone increased the body weight and tibial muscle mass of the rats markedly, while EX caused a slight decrease in body weight and partially inhibited the increase caused by GH in the GH+EX group. Food restriction greatly decreased body weight below that of age-matched controls but neither FR nor EX had a significant effect on the mass of the muscles around the tibia. Growth hormone and EX independently increased tibial diaphyseal cortical bone area (p<0.0001), cortical thickness (p<0.0001), cortical bone mineral content (p<0.0001), periosteal perimeter (p<0.0001) and bone strength-strain index (SSI) (p<0.0001). The effects of GH were more marked, and the combination of GH and EX produced additive effects on many of the tibial diaphyseal parameters including bone SSI. GH+EX, but not GH or EX alone caused a significant increase in endocortical perimeter (p<0.0001). In the FR rats, cortical bone area and cortical mineral content increased above the baseline level (p<0.0001) but were below the levels for age-matched controls (p<0.0001). In addition, marrow area, endocortical perimeter and endocortical bone formation rate increased significantly in the FR rats (p<0.01, p<0.0001, p<0.0001). Three-point bending test of right tibial diaphysis resulted in maximum force (Fmax) values that reflected the group differences in indices of tibial diaphyseal bone mass except that GH+EX did not produce additive effect on Fmax. The latter showed good correlation with left tibial diaphyseal SSI (r=0.857, p<0.0001) and both indices of bone strength correlated well with tibial muscle mass (r=0.771, Fmax; r=0.700, SSI; p<0.0001). We conclude that the bone anabolic effects of GH with or without EX may relate, in part, to increased load on bone from tibial muscles and body weight, which were increased by the hormone. The osteogenic effects of EX with or without GH may relate, in part, to increased frequency of muscle load on bone as EX decreased body weight (p<0.05) but had no significant effect on tibial muscle mass. The enhanced loss of endocortical bone by FR may relate, in part, to decreased load on bone due to low body weight (p<0.0001) as FR did not cause a significant decrease in tibial muscle mass (p=0.357). The roles of humoral and local factors in the bone changes observed remain to be established.     

Bone structure and density via HR-pQCT in 60d bed-rest, 2-years recovery with and without countermeasures

We examined the effects of bed-rest, recovery and exercise countermeasures on bone density and structure at the distal tibia and radius as measured via high-resolution peripheral computed tomography. 24 subjects underwent 60-days of head-down tilt bed-rest and performed either resistive vibration exercise (RVE; n = 7), resistive exercise only (RE; n = 8) or no exercise (n = 9; 2nd Berlin BedRest Study; BBR2-2). Measurements were performed regularly during and up to 2-years after 60d bed-rest. At the distal tibia marked reductions in cortical area, cortical thickness and bone density but increases in periosteal perimeter and trabecular area were seen (p all<0.001). Recovery of most parameters occurred within 180d after bed-rest. At the distal radius, persistent increases in cortical area, cortical thickness, cortical density and total density and decreases in trabecular area were seen (p all ≤ 0.005). A significant effect of RVE (p = 0.003), but not RE, was seen on cortical area at the distal tibia, with few effects of the countermeasures observed on the remaining parameters. The current study represents the first implementation of high-resolution peripheral computed tomography in bed-rest in male subjects and helps to understand the patterns of bone remodeling due to bed-rest and recovery.     

Estimation of bone mineral density and architectural parameters of the distal radius in hemodialysis patients using peripheral quantitative computed tomography

We analyzed bone changes in a series of hemodialysis patients followed up for a maximum of 299 months by assessing bone mineral density (BMD) and architectural parameters of the distal radius using peripheral quantitative computed tomography (pQCT), and determined the predictors of skeletal changes in these patients. No significant differences in trabecular BMD (BMD(T)) were found compared with BMD(T) of the normal control. In contrast, cortical BMD (BMD(C)) was significantly decreased compared with BMD(C) of the normal controls. Hemodialysis patients had significantly lower values for cortical bone area, cortical thickness, moment of inertia, and polar moment of inertia than the age-matched controls. From single and multiple regression analysis, the most significant predictor of metabolic bone disease in these cases was found to be duration of hemodialysis. In addition, increases in serum alkaline phosphatase and intact parathyroid hormone in secondary hyperparathyroidism were found to correlate with a decrease in pQCT values in cortical bone; as such, these increases were also found to be a predictive. The present study confirms that the reduction in both BMD(C) and architectural parameters in hemodialysis patients occurs partly because of prolonged hemodialysis and secondary hyperparathyroidism. In addition, immobilization, dietary factors, daily intake of calcium or vitamin D, and so on must be taken into account when clarifying the causes of skeletal complications resulting from hemodialysis.     

Volumetric and projective bone mineral density

Projectional bone mineral density measurement so far used extensively in radiogrammetry and single and dual source absorptiometry is confronted with a serious limitation for the accurate evaluation of true density artifactually providing higher values along with the increase of body size and bone depth on account of the omission of one dimension. Computed tomography is capable of measuring true volumetric density and also accomplishes a separate measurement of trabecular and cortical bone especially on application to the distal and mid-radius with abundant cortical bone in peripheral computed tomography (pQCT). New lines of information may be obtained by such separate trabecular and cortical bone measurement in decreases of bone density due to various causes, estrogen withdrawal, corticosteroid, diabetes mellitus, renal failure, etc. Dynamic analysis of the result of pQCT may also make it possible to assess bone strength and resistance to fracture.     

Hormone replacement therapy improves distal radius bone structure by endocortical mineral deposition

Hormone replacement therapy (HRT) produces a small increase in bone mineral density (BMD) when measured by dual energy X-ray absorptiometry (DXA). The corresponding decrease in fracture risk is more impressive, implying that other factors that contribute to bone strength are favourably modified by HRT. We investigated, using peripheral quantitated computed tomography (pQCT), the changes produced by HRT in both the distribution of mineral between cortical and trabecular bone and the changes produced by HRT in the apparent structure of trabecular bone, expressed as average hole area and apparent connectivity. Twenty-one postmenopausal women starting HRT and 32 control women were followed for 2 years, with distal radius pQCT measurements every 6 months. HRT prevented the loss of total bone mass seen in controls (p < 0.02). HRT also produced an apparent rapid loss of trabecular bone mass within the first 6 months of the study (p < 0.02), with an associated rapid loss in the apparent connectivity (p = 0.034). Average hole area also increased but not to a statistically significant extent. Exogenous estrogen apparently fills small marrow pores close to the endocortical surface, such that the pQCT-defined boundary between trabecular and cortical bone is shifted in favour of cortical bone. Trabecular bone structure indices are adversely affected, as the central, poorly interconnected trabecular bone with greater than average marrow spaces constitutes a greater fraction of the remaining trabecular bone. This study suggests that the improvements in fracture risk resulting from HRT are explained by a reversal of net endocortical resorption of bone.     

Side-to-side differences in bone strength in master jumpers and sprinters

Introduction: This study evaluated side-to-side difference in tibial bone structure, calf muscle cross-sectional area (CSA) and hopping force in master athletes as a result of training for sports with different magnitudes of inter-leg loading difference. Methods: Tibial bone parameters (at 4%, 14%, 38% and 66% tibial length proximal to distal end), muscle CSA (at 66% tibial length) and hopping forces of both legs of 51 master athletes (conditioned jumpers, conditioned triple jumpers, unconditioned jumpers, hurdlers and sprinters) were examined using pQCT. In epiphyseal 4% slice bone CSA (Ar.tot), total BMC (vBMC.tot), trabecular BMC (vBMC.tb) cortical BMC (vBMC.ct), and trabecular BMD (vBMD.tb) were measured. In diaphyseal slices, Ar.tot, vBMC.ct, cortical density (vBMD.ct), cross-sectional moment of inertia (CSMI) and calf muscle CSA (MuscA) were examined. Results: In conditioned jumpers, side-to-side differences in favour of take-off leg were found in 4% slice in vBMC.tb (+4.1%) (P<0.05). A side-to-side difference was found in 66% slice vBMC.ct and CSMI (both P<0.05), with conditioned jumper (+2.8% and 6.6%) and triple jumper (+2.7% and 7.2%) values higher than other groups. Conclusion: The results suggest that regular training in high-impact sports with uneven lower limb loading results in side-to-side differences in skeletal adaptation independent of age and gender, suggesting that high-impact exercise is effective in maintaining bone strength throughout human lifespan.     

Interleukin-15 and interleukin-15R alpha SNPs and associations with muscle, bone, and predictors of the metabolic syndrome

The aims of this study were to examine associations between two SNPs in the human IL-15 gene and three SNPs in the IL-15Ralpha gene with predictors of metabolic syndrome and phenotypes in muscle, strength, and bone at baseline and in response to resistance training (RT). Subjects were Caucasians who had not performed RT in the previous year and consisted of a strength cohort (n=748), volumetric cohort (n=722), and serum cohort (n=544). Subjects completed 12 weeks of unilateral RT of the non-dominant arm, using their dominant arm as an untrained control. ANCOVA analyses revealed gender-specific associations with: (1) IL-15 SNP (rs1589241) and cholesterol (p=0.04), LDL (p=0.02), the homeostasis model assessment (HOMA; p=0.03), and BMI (p=0.002); (2) IL-15 SNP (rs1057972) and the pre- to post-training absolute difference in 1RM strength (p=0.02), BMI (p=0.008), and fasting glucose (p=0.03); (3) IL-15Ralpha SNP (rs2296135) and baseline total bone volume (p=0.04) and the pre- to post-training absolute difference in isometric strength (p=0.01); and 4) IL-15Ralpha SNP (rs2228059) and serum triglycerides (p=0.04), baseline whole muscle volume (p=0.04), baseline cortical bone volume (p=0.04), and baseline muscle quality (p=0.04). All associations were consistent in showing a potential involvement of the IL-15 pathway with muscle and bone phenotypes and predictors of metabolic syndrome.     

Functional assessment of the muscle-bone unit in the lower leg

Based on the mechanostat theory and the muscle-bone hypothesis, a methodological assessment of the musculoskeletal status in health and disease should relate maximum muscle force in relation to bone mass and geometry. While useful (i.e. three-dimensional) measures of tibial bone parameters can be obtained by peripheral quantitative computed tomography (pQCT), intrinsic plantarflexor muscle force cannot be directly measured under in vivo condition in humans. Instead, tissue size, torque and ground reaction force have been used as proxy markers of intrinsic muscle force. However, most of these proxy markers are not or insufficiently representative of maximum force. Based on our recent research, we describe a novel approach for the assessment of the lower leg muscle-bone unit in health and disease. It incorporates multiple one-legged hopping (m1LH) to assess maximum voluntary ground reaction force acting on the forefoot (F(m1LH)) and bone mineral content at the 14%-site of tibia length (vBMC(14%)) as assessed by pQCT. Using the quantitative relationship between these two variables in conjunction with F(m1LH) per body weight, we present a two-step quantitative diagnostic algorithm to discriminate between primary and secondary bone disorders in children and adults.     

Peripheral quantitative computed tomography at the distal radius: cross-calibration between two scanners

Peripheral quantitative computed tomography (pQCT) is an important technique to study the interaction between the muscle and bone systems. We have recently established pQCT reference ranges for children, adolescents and young adults using a recent version (XCT 2000) of the Stratec scanners (Stratec Inc., Pforzheim, Germany). However, the previous version of this type of scanner (XCT 900) is still widely used and cross-calibration is needed to use these reference data. Therefore, both distal radii of 19 healthy subjects (age 21 to 59 years; 11 women) were analyzed at the "4% site" using both the XCT 900 and the XCT 2000. Cross-sectional area, total and trabecular bone mineral density (BMD), total bone mineral content (BMC) and polar Strength-Strain Index (SSI) results from the two scanners were compared using linear regression analysis. To achieve scanner calibration we used the intercept and slope of the correlations. The correlation coefficients between the two devices were 0.82 for the cross-sectional area, 0.81 for total BMD, 0.97 for trabecular BMD, 0.99 for total BMC and 0.86 for polar SSI. In conclusion, these data allow for the conversion of XCT 900 results at the distal radius to XCT 2000 values and vice versa.     

A Piece of the Puzzle: The Bone Health Index of the BoneXpert Software Reflects Cortical Bone Mineral Density in Pediatric and Adolescent Patients

Introduction

Suspected osteopathology in chronically ill children often necessitates the assessment of bone mineral density. The most frequently used methods are dual-energy X-ray-absorption (DXA) and peripheral quantitative computed tomography (pQCT). The BoneXpert software provides an automated radiogrammatic method to assess skeletal age from digitalized X-rays of the left hand. Furthermore, the program calculates the Bone Health Index (BHI), a measure of cortical thickness and mineralization, which is obtained from indices of three metacarpal bones. In our study, we analyzed the manner in which BHI information provided by BoneXpert compares with DXA or pQCT measurements in youths.

Study Design

The BHI was retrospectively obtained using digitalized X-rays of the left hand and compared with the results of 203 corresponding DXA readings (Lunar Prodigy, GE Healthcare) of the lumbar vertebrae and femur as well as 117 pQCT readings (XCT 900, Stratec) of the distal radius.

Results

The BHI values showed a strong positive correlation with the DXA readings at each and all lumbar vertebrae (L1 –L4: r = 0.73; P < 0.0001). The age-adjusted Z-score of L1 –L4 and the height-adjusted score showed a positive correlation with the BHI-SDS (standard deviation score, r = 0.23; P < 0.002 and r = 0.27; P < 0.001, respectively). Total bone mineral density, as assessed via pQCT, also positively correlated with the BHI (r = 0.39; P < 0.0001), but the trabecular values displayed only a weak correlation.

Conclusions

The BHI obtained using BoneXpert can be a useful parameter in the assessment of bone health in children in most cases. This technique provides observer-independent information on cortical thickness and mineralization based on X-ray imaging of the hands.