Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows.

The 6th International Conference, "Controversies in Vitamin D," was convened to discuss controversial topics, such as vitamin D metabolism, assessment, actions, and supplementation. Novel insights into vitamin D mechanisms of action suggest links with conditions that do not depend only on reduced solar exposure or diet intake and that can be detected with distinctive noncanonical vitamin D metabolites. Optimal 25-hydroxyvitamin D (25(OH)D) levels remain debated. Varying recommendations from different societies arise from evaluating different clinical or public health approaches. The lack of assay standardization also poses challenges in interpreting data from available studies, hindering rational data pooling and meta-analyses. Beyond the well-known skeletal features, interest in vitamin D's extraskeletal effects has led to clinical trials on cancer, cardiovascular risk, respiratory effects, autoimmune diseases, diabetes, and mortality. The initial negative results are likely due to enrollment of vitamin D-replete individuals. Subsequent post hoc analyses have suggested, nevertheless, potential benefits in reducing cancer incidence, autoimmune diseases, cardiovascular events, and diabetes. Oral administration of vitamin D is the preferred route. Parenteral administration is reserved for specific clinical situations. Cholecalciferol is favored due to safety and minimal monitoring requirements. Calcifediol may be used in certain conditions, while calcitriol should be limited to specific disorders in which the active metabolite is not readily produced in vivo. Further studies are needed to investigate vitamin D effects in relation to the different recommended 25(OH)D levels and the efficacy of the different supplementary formulations in achieving biochemical and clinical outcomes within the multifaced skeletal and extraskeletal potential effects of vitamin D.

The relationship between bone strain index, bone mass, microarchitecture and mechanical behavior in human vertebrae: an ex vivo study.

The aim of this study was to determine whether the Bone Strain Index (BSI), a recent DXA-based bone index, is related to bone mechanical behavior, microarchitecture and finally, to determine whether BSI improves the prediction of bone strength and the predictive role of BMD in clinical practice. PURPOSE: Bone Strain Index (BSI) is a new DXA-based bone index that represents the finite element analysis of the bone deformation under load. The current study aimed to assess whether the BSI is associated with 3D microarchitecture and the mechanical behavior of human lumbar vertebrae. METHODS: Lumbar vertebrae (L3) were harvested fresh from 31 human donors. The anteroposterior BMC (g) and aBMD (g/cm2) of the vertebral body were measured using DXA, and then the BSI was automatically derived. The trabecular bone volume (Tb.BV/TV), trabecular thickness (Tb.Th), degree of anisotropy (DA), and structure model index (SMI) were measured using µCT with a 35-µm isotropic voxel size. Quasi-static uniaxial compressive testing was performed on L3 vertebral bodies under displacement control to assess failure load and stiffness. RESULTS: The BSI was significantly correlated with failure load and stiffness (r = -0.60 and -0.59; p < 0.0001), aBMD and BMC (r = -0.93 and -0.86; p < 0.0001); Tb.BV/TV and SMI (r = -0.58 and 0.51; p = 0.001 and 0.004 respectively). After adjustment for aBMD, the association between BSI and stiffness, BSI and SMI remained significant (r = -0.51; p = 0.004 and r = -0.39; p = 0.03 respectively, partial correlations) and the relation between BSI and failure load was close to significance (r = -0.35; p = 0.06). CONCLUSION: The BSI was significantly correlated with the microarchitecture and mechanical behavior of L3 vertebrae, and these associations remained statistically significant regardless of aBMD.

Use of vitamin D with anti-osteoporotic drugs: are available clinical trials telling us the whole story?

There is a strong rationale for using vitamin D in combination with anti-osteoporotic drugs. Still, available trials do not give clear indications in this setting, presenting a suboptimal and heavily inhomogeneous experimental design. Health authorities should revise requirements for using vitamin D in anti-osteoporotic drug trials to maximise their effect and produce reliable indications for clinical practice in this setting.

Vitamin D status and supplementation before and after Bariatric Surgery: Recommendations based on a systematic review and meta-analysis.

Bariatric surgery is associated with a postoperative reduction of 25(OH) vitamin D levels (25(OH)D) and with skeletal complications. Currently, guidelines for 25(OH)D assessment and vitamin D supplementation in bariatric patients, pre- and post-surgery, are still lacking. The aim of this work is to analyse systematically the published experience on 25(OH)D status and vitamin D supplementation, pre- and post-surgery, and to propose, on this basis, recommendations for management. Preoperatively, 18 studies including 2,869 patients were evaluated. Prevalence of vitamin D insufficiency as defined by 25(OH)D < 30 ng/mL (75 nmol/L) was 85%, whereas when defined by 25(OH)D < 20 ng/mL (50 nmol/L) was 57%. The median preoperative 25(OH)D level was 19.75 ng/mL. After surgery, 39 studies including 5,296 patients were analysed and among those undergoing either malabsorptive or restrictive procedures, a lower rate of vitamin D insufficiency and higher 25(OH)D levels postoperatively were observed in patients treated with high-dose oral vitamin D supplementation, defined as ≥ 2,000 IU/daily (mostly D3-formulation), compared with low-doses (< 2,000 IU/daily). Our recommendations based on this systematic review and meta-analysis should help clinical practice in the assessment and management of vitamin D status before and after bariatric surgery. Assessment of vitamin D should be performed pre- and postoperatively in all patients undergoing bariatric surgery. Regardless of the type of procedure, high-dose supplementation is recommended in patients after bariatric surgery.

Dual X-ray absorptiometry-derived bone status indexes and videocapsule intestinal aspects in celiac disease.

BACKGROUND AND AIM: Celiac disease is a risk factor for osteopenia and osteoporosis. Our aim was to evaluate the possible correlation between villous atrophy extension and dual-energy X-ray absorptiometry (DXA)-derived parameters of bone status. METHODS: We have retrospectively analyzed data of 47 celiac patients (36 women, 52 ± 14 years of age) who underwent video capsule endoscopy and DXA scans within 1 year of interval from 2006 to 2019. Quantitative, qualitative and geometric DXA parameters were collected only from the most recent DXA measurements. RESULTS: . Patients were divided into three categories; the first included those with no lesions at video capsule endoscopy (23 patients), the second those with typical lesions (mucosal atrophy, mosaicism and scalloping) in less than one-third of the small bowel (SB) (16 patients) and the third those with typical lesions in more than one-third of the SB (7 patients). In the third group, bone mineral density seemed to be lower in both the lumbar spine and the hip ( P = 0.026 and P = 0.011, respectively). The deterioration of bone structure in patients with severe and extended SB atrophy was statistically significant ( P = 0.032). Furthermore, bone density, structure and geometry did not correlate with the duration of the gluten-free diet. Notably, autoimmune comorbidities did not affect DXA results. CONCLUSION: Neither endoscopic nor histological atrophy itself can explain the deterioration of bone mineralization and structure, whereas atrophy extension appeared to be responsible for bone impairment.

DXA-based bone strain index in normocalcemic primary hyperparathyroidism.

The trabecular and cortical bone assessed by bone strain index seems not to be significantly affected in NHPT. INTRODUCTION: The natural history and bone involvement of normocalcemic hyperparathyroidism (NHPT) are not fully clarified yet. The bone strain index (BSI) is a deformation index based on the finite element method and can be applied to DXA scans. In this study, we aim to assess BSI in subjects with NHPT. METHOD: A case-control study included 170 subjects: 40 subjects with NHPT, 50 subjects with primary hypercalcemic hyperparathyroidism (PHPT), and 80 controls (age- and sex-matched with the NPTH group). RESULTS: Lumbar spine (LS) bone mineral density (BMD), femoral neck (FN) BMD, total hip (TH) BMD, and TBS were similar between NHPT and both PHPT and controls. FN-BSI was lower in NHPT compared to PHPT (1.52 ± 0.31 vs 1.72 ± 0.42 p = 0.031) while there were no differences between NHPT and controls. TH-BSI was lower in NHPT compared to PHPT (1.36 ± 0.23 vs 1.52 ± 0.34, p = 0.030), while there were no differences between NHPT and controls. LS-BSI was not different between NHPT and both PHPT and controls. CONCLUSION: The trabecular and cortical bones assessed by BSI seem not to be significantly impaired in NHPT. Further prospective studies are needed to confirm these findings and to give an insight into the natural history of NHPT to improve knowledge and management of this condition.

Assessment of DXA derived bone quality indexes and bone geometry parameters in early breast cancer patients: A single center cross-sectional study.

Background: Bone mineral density (BMD) lacks sensitivity in individual fracture risk assessment in early breast cancer (EBC) patients treated with aromatase inhibitors (AIs). New dual-energy X-ray absorptiometry (DXA) based risk factors are needed. Methods: Trabecular bone score (TBS), bone strain index (BSI) and DXA parameters of bone geometry were evaluated in postmenopausal women diagnosed with EBC. The aim was to explore their association with morphometric vertebral fractures (VFs). Subjects were categorized in 3 groups in order to evaluate the impact of AIs and denosumab on bone geometry: AI-naive, AI-treated minus (AIDen-) or plus (AIDen+) denosumab. Results: A total of 610 EBC patients entered the study: 305 were AI-naive, 187 AIDen-, and 118 AIDen+. In the AI-naive group, the presence of VFs was associated with lower total hip BMD and T-score and higher femoral BSI. As regards as bone geometry parameters, AI-naive fractured patients reported a significant increase in femoral narrow neck (NN) endocortical width, femoral NN subperiosteal width, intertrochanteric buckling ratio (BR), intertrochanteric endocortical width, femoral shaft (FS) BR and endocortical width, as compared to non-fractured patients. Intertrochanteric BR and intertrochanteric cortical thickness significantly increased in the presence of VFs in AIDen- patients, not in AIDen+ ones. An increase in cross-sectional area and cross-sectional moment of inertia, both intertrochanteric and at FS, significantly correlated with VFs only in AIDen+. No association with VFs was found for either lumbar BSI or TBS in all groups. Conclusions: Bone geometry parameters are variably associated with VFs in EBC patients, either AI-naive or AI treated in combination with denosumab. These data suggest a tailored choice of fracture risk parameters in the 3 subgroups of EBC patients.

Bone Strain Index: preliminary distributional characteristics in a population of women with normal bone mass, osteopenia and osteoporosis.

PURPOSE: Bone Strain Index (BSI) is a recently developed dual-energy X-ray absorptiometry (DXA) software, applying a finite element analysis on lumbar spine and femoral DXA scans. BSI is a parameter of bone deformation, providing information on bone resistance to applied loads. BSI values indicate the average bone strain in the explored site, where a higher strain (higher BSI values) suggests a higher fracture risk. This study reports the distributional characteristics of lumbar BSI (L-BSI) in women with normal bone mass, osteopenia or osteoporosis and their relationships with BMD, weight, height and BMI. MATERIAL AND METHODS: Two-hundred-fifty-nine consecutive unfractured women who performed DXA were divided into three groups based on BMD T-score: normal bone mass (n = 43, 16.6%), osteopenia (n = 82, 31.7%) and osteoporosis (n = 134, 51.7%). The distribution of L-BSI was evaluated with conventional statistical methods, histograms and by calculating parametric and nonparametric 95% confidence intervals, together with the 90%, 95% and 99% bilateral tolerance limits with a 95% confidence. RESULTS: Ninety percent bilateral tolerance limits with 95% confidence for L-BSI distribution are 1.0-2.40, 0.95-2.63 and 0.84-3.15 in the group of patients with normal bone mass, 1.34-2.78, 1.24-2.95 and 1.05-3.32 in the osteopenic group and 1.68-3.79, 1.58-4.15 and 1.40-4.96 in the osteoporotic group. CONCLUSION: In women without vertebral fractures at baseline, L-BSI values from 1.68 (osteoporotic group) and 2.40 (upper of the normal bone mass group) can be tentatively chosen as a lower and upper threshold to stratify postmenopausal women according to their bone resistance to loads.

A single-centre study on predictors and determinants of pubertal delay and growth impairment in Epidermolysis Bullosa.

BACKGROUND: Delayed puberty is a possible complication of Epidermolysis Bullosa (EB), though the actual incidence is still unknown. In chronic illnesses delayed puberty should be correctly managed since, if untreated, can have detrimental effects on adult height attainment, peak bone mass achievement and psychological health. AIMS AND METHODS: This is a single-centre study on pubertal development, growth and bone status in EB. Auxological, densitometric (areal Bone Mineral Density-aBMD Z-score, Bone Mineral Apparent Density-BMAD Z-score, Trabecular Bone Score-TBS and Bone Strain Index-BSI at Lumbar spine) and body composition data (Total Body DXA scans) were collected. Disease severity was defined according to Birmingham Epidermolysis Bullosa Severity (BEBS) score. RESULTS: Twenty-one patients (12 Recessive Dystrophic EB-RDEB, 3 Dominant Dystrophic EB, 3 Junctional EB-JEB, 2 EB Simplex and one Kindler EB) aged 13 years (females) or 14 years (males) and above were enrolled (age 16.2±2.5 years, M/F 11/10). Short stature was highly prevalent (57%, mean height -2.12±2.05 SDS) with 55% patients with height <-2SD their mid-parental height. 7/21 patients (33%, 6 RDEB and 1 JEB) had delayed puberty with a median BEBS of 50 (range 29 to 63), a height SDS of -2.59 SDS (range -5.95 to -2.22) and a median lumbar BMAD Z-score of -4.0 SDS (range -5.42 to -0.63 SDS). Pubertal status was negatively associated with BEBS, skin involvement, inflammatory state and positively with height SDS and BMI SDS. CONCLUSIONS: Pubertal delay is highly prevalent in EB, especially in patients with RDEB and JEB, high severity score and inflammatory state. Moreover, pubertal delay worsens growth impairment and bone health. A study on pubertal induction is ongoing to enlighten possible beneficial effects on adult height attainment and peak bone mass accrual.

The Bone Strain Index: An Innovative Dual X-ray Absorptiometry Bone Strength Index and Its Helpfulness in Clinical Medicine.

Bone strain Index (BSI) is an innovative index of bone strength that provides information about skeletal resistance to loads not considered by existing indexes (Bone Mineral Density, BMD. Trabecular Bone Score, TBS. Hip Structural Analysis, HSA. Hip Axis Length, HAL), and, thus, improves the predictability of fragility fractures in osteoporotic patients. This improved predictability of fracture facilitates the possibility of timely intervention with appropriate therapies to reduce the risk of fracture. The development of the index was the result of combining clinical, radiographical and construction-engineering skills. In fact, from a physical point of view, primary and secondary osteoporosis, leading to bone fracture, are determined by an impairment of the physical properties of bone strength: density, internal structure, deformation and fatigue. Dual X-ray absorptiometry (DXA) is the gold standard for assessing bone properties, and it allows measurement of the BMD, which is reduced mainly in primary osteoporosis, the structural texture TBS, which can be particularly degraded in secondary osteoporosis, and the bone geometry (HSA, HAL). The authors recently conceived and developed a new bone deformation index named Bone Strain Index (BSI) that assesses the resistance of bone to loads. If the skeletal structure is equated to engineering construction, these three indexes are all considered to determine the load resistance of the construct. In particular, BSI allows clinicians to detect critical information that BMD and TBS cannot explain, and this information is essential for an accurate definition of a patient's fracture risk. The literature demonstrates that both lumbar and femoral BSI discriminate fractured osteoporotic people, that they predict the first fragility fracture, and further fragility fractures, monitor anabolic treatment efficacy and detect patients affected by secondary osteoporosis. BSI is a new diagnostic tool that offers a unique perspective to clinical medicine to identify patients affected by primary and, specially, secondary osteoporosis. This literature review illustrates BSI's state of the art and its ratio in clinical medicine.

The bone strain index predicts fragility fractures. The OFELY study.

Recently, the bone strain index (BSI), a new index of bone strength based on a finite element model (FEA) from dual X-ray absorptiometry (DXA), has been developed. BSI represents the average equivalent strain inside the bone, assuming that a higher strain level (high BSI) indicates a condition of higher risk. Our study aimed to analyze the relationship between BSI and age, BMI and areal BMD in pre- and postmenopausal women and to prospectively investigate fracture prediction (Fx) by BSI in postmenopausal women. Methods. At the 14th annual follow-up of the OFELY study, BSI was measured at spine (Spine BSI) and femoral scans (Neck and Total Hip BSI), in addition to areal BMD with DXA (Hologic QDR 4500) in 846 women, mean (SD) age 60 yr (15). The FRAX® (fracture risk assessment tool) for major osteoporotic fractures (MOF) was calculated with FN areal BMD (aBMD) at baseline; incident fragility fractures were annually registered until January 2016. Results. In premenopausal women (n = 261), Neck and Total Hip BSI were slightly negatively correlated with age (Spearman r = -0.13 and -0.15 respectively, p = 0.03), whereas all BSIs were positively correlated with BMI (r = +0.20 to 0.37, p < 0.01) and negatively with BMD (r = -0.69 to -0.37, p < 0.0001). In postmenopausal women (n = 585), Neck and Total Hip BSI were positively correlated with age (Spearman r = +0.26 and +0.31 respectively, p < 0.0001), whereas Spine BSI was positively correlated with BMI (r = +0.22, p < 0.0001) and all BSIs were negatively correlated with BMD (r = -0.81 to -0.60, p < 0.0001). During a median [IQ] 9.3 [1.0] years of follow-up, 133 postmenopausal women reported an incident fragility Fx, including 80 women with a major osteoporotic Fx (MOF) and 26 women with clinical vertebral Fx (VFx). Each SD increase of BSI value was associated with a significant increase of the risk of all fragility Fx with an age-adjusted HR of 1.23 for Neck BSI (p = 0.02); 1.27 for Total Hip BSI (p = 0.004) and 1.35 for Spine BSI (p < 0.0001). After adjustment for FRAX®, the association remained statistically significant for Total Hip BSI (HR 1.24, p = 0.02 for all fragility Fx; 1.31, p = 0.01 for MOF) and Spine BSI (HR 1.33, p < 0.0001 for all fragility Fx; 1.33, p = 0.005 for MOF; 1.67, p = 0.002 for clinical VFx). In conclusion, spine and femur BSI, an FEA DXA derived index, predict incident fragility fracture in postmenopausal women, regardless of FRAX®.

Bone Strain Index predicts fragility fracture in osteoporotic women: an artificial intelligence-based study.

BACKGROUND: We applied an artificial intelligence-based model to predict fragility fractures in postmenopausal women, using different dual-energy x-ray absorptiometry (DXA) parameters. METHODS: One hundred seventy-four postmenopausal women without vertebral fractures (VFs) at baseline (mean age 66.3 ± 9.8) were retrospectively evaluated. Data has been collected from September 2010 to August 2018. All subjects performed a spine x-ray to assess VFs, together with lumbar and femoral DXA for bone mineral density (BMD) and the bone strain index (BSI) evaluation. Follow-up exams were performed after 3.34 ± 1.91 years. Considering the occurrence of new VFs at follow-up, two groups were created: fractured versus not-fractured. We applied an artificial neural network (ANN) analysis with a predictive tool (TWIST system) to select relevant input data from a list of 13 variables including BMD and BSI. A semantic connectivity map was built to analyse the connections among variables within the groups. For group comparisons, an independent-samples t-test was used; variables were expressed as mean ± standard deviation. RESULTS: For each patient, we evaluated a total of n = 6 exams. At follow-up, n = 69 (39.6%) women developed a VF. ANNs reached a predictive accuracy of 79.56% within the training testing procedure, with a sensitivity of 80.93% and a specificity of 78.18%. The semantic connectivity map showed that a low BSI at the total femur is connected to the absence of VFs. CONCLUSION: We found a high performance of ANN analysis in predicting the occurrence of VFs. Femoral BSI appears as a useful DXA index to identify patients at lower risk for lumbar VFs.

2D and 3D numerical models to evaluate trabecular bone damage.

The comprehension of trabecular bone damage processes could be a crucial hint for understanding how bone damage starts and propagates. Currently, different approaches to bone damage identification could be followed. Clinical approaches start from dual X-ray absorptiometry (DXA) technique that can evaluate bone mineral density (BMD), an indirect indicator of fracture risk. DXA is, in fact, a two-dimensional technology, and BMD alone is not able to predict the effective risk of fractures. First attempts in overcoming this issue have been performed with finite element (FE) methods, combined with the use of three-dimensional high-resolution micro-computed tomographic images. The purpose of this work is to evaluate damage initiation and propagation in trabecular vertebral porcine samples using 2D linear-elastic FE models from DXA images and 3D linear FE models from micro-CT images. Results show that computed values of strains with 2D and 3D approaches (e.g., the minimum principal strain) are of the same order of magnitude. 2D DXA-based models still remain a powerful tool for a preliminary screening of trabecular regions that are prone to fracture, while from 3D micro-CT-based models, it is possible to reach details that permit the localization of the most strained trabecula.

Vitamin D in the Covid-19 era: a review with recommendations from a G.I.O.S.E.G. expert panel.

Vitamin D (VITD) is a key hormone for bone health and has relevant extra-skeletal effects that might play a role in the prevention and treatment of COronaVIrus Disease 19 (COVID-19). Literature regarding this scenario is voluminous but controversial. Glucocorticoid Induced Osteoporosis Skeletal Endocrinology Group (G.I.O.S.E.G) has been present in the scientific debate about the use of VITD and has regularly interfaced national regulatory agencies to ensure appropriateness of its employment. Given the current pandemic and the questions on COVID-19 and VITD, G.I.O.S.E.G. appointed an expert panel to advise how to consider this issue best. The results of these deliberations are reported in the current recommendation paper.

Osteopathy in mild adrenal Cushing's syndrome and Cushing disease.

Pathophysiology and effects of endogenous glucocorticoid (GC) excess on skeletal endpoints as well as awareness and management of bone fragility are reviewed. Cushing's syndrome (CS) increase the risk of fracture affecting prevalently bone quality. Bone antiresorptive agents (SERMs, bisphosphonates and denosumab) as well as teriparatide increase bone mineral density and in some instances reduce fracture risk. Awareness and management of bone health in CS can be improved.

A case of aggressive systemic mastocytosis with bulky lymphadenopathy showing response to midostaurin.

Management of systemic mastocytosis is an emerging challenge which requires a multidisciplinary diagnostic approach and personalized treatment strategy. Midostaurin can rapidly reduce the disease burden, also in cladribine refractory cases.

Bone strain index as a predictor of further vertebral fracture in osteoporotic women: An artificial intelligence-based analysis.

BACKGROUND: Osteoporosis is an asymptomatic disease of high prevalence and incidence, leading to bone fractures burdened by high mortality and disability, mainly when several subsequent fractures occur. A fragility fracture predictive model, Artificial Intelligence-based, to identify dual X-ray absorptiometry (DXA) variables able to characterise those patients who are prone to further fractures called Bone Strain Index, was evaluated in this study. METHODS: In a prospective, longitudinal, multicentric study 172 female outpatients with at least one vertebral fracture at the first observation were enrolled. They performed a spine X-ray to calculate spine deformity index (SDI) and a lumbar and femoral DXA scan to assess bone mineral density (BMD) and bone strain index (BSI) at baseline and after a follow-up period of 3 years in average. At the end of the follow-up, 93 women developed a further vertebral fracture. The further vertebral fracture was considered as one unit increase of SDI. We assessed the predictive capacity of supervised Artificial Neural Networks (ANNs) to distinguish women who developed a further fracture from those without it, and to detect those variables providing the maximal amount of relevant information to discriminate the two groups. ANNs choose appropriate input data automatically (TWIST-system, Training With Input Selection and Testing). Moreover, we built a semantic connectivity map usingthe Auto Contractive Map to provide further insights about the convoluted connections between the osteoporotic variables under consideration and the two scenarios (further fracture vs no further fracture). RESULTS: TWIST system selected 5 out of 13 available variables: age, menopause age, BMI, FTot BMC, FTot BSI. With training testing procedure, ANNs reached predictive accuracy of 79.36%, with a sensitivity of 75% and a specificity of 83.72%. The semantic connectivity map highlighted the role of BSI in predicting the risk of a further fracture. CONCLUSIONS: Artificial Intelligence is a useful method to analyse a complex system like that regarding osteoporosis, able to identify patients prone to a further fragility fracture. BSI appears to be a useful DXA index in identifying those patients who are at risk of further vertebral fractures.

Operator-Related Errors and Pitfalls in Dual Energy X-Ray Absorptiometry: How to Recognize and Avoid Them.

Dual-energy X-ray absorptiometry (DXA) is the most common modality for quantitative measurements of bone mineral density. Nevertheless, errors related to this exam are still very common, and may significantly impact on the final diagnosis and therapy. Operator-related errors may occur during each DXA step and can be related to wrong patient positioning, error in the acquisition process or in the scan analysis. The aim of this review is to provide a practical guide on how to recognize such errors in spine and hip DXA scan and how to avoid them, also presenting some of the most common artifacts encountered in clinical practice.

Short-Term Precision Error of Bone Strain Index, a New DXA-Based Finite Element Analysis Software for Assessing Hip Strength.

Bone Strain Index (BSI) is a new finite element analysis tool applied to hip dual energy X-ray absorptiometry scans. The aim of this study was to assess the short-term precision error of BSI on the proximal femur, both on a phantom and patients. The International Society for Clinical Densitometry guidelines were followed for short-term precision error assessment. Dual energy X-ray absorptiometry measurements were performed on an anthropomorphic femur phantom that was scanned twice for 30 times, for a total of 60 scans. For the in vivo part, 30 subjects were scanned twice. BSI precision error was compared to that of bone mineral density (BMD). Both for the phantom and the in vivo study BSI reproducibility was lower compared to that of BMD, as the precision error of BSI resulted 3 times higher compared to that BMD. For phantom measurements, the highest precision value was that of total femur (TF) BMD (coefficient of variation [CoV] = 0.63%, reproducibility = 98.24%), while the lowest precision was the femoral neck (FN) BSI (CoV = 3.08%, reproducibility = 91.48%). Similarly, for the in vivo study, the highest precision was found at TF BMD (CoV = 1.36%, reproducibility = 96.22%), while the lowest value of precision was found for FN BSI (CoV = 4.17%, reproducibility = 88.46%). Reproducibility at TF was always better compared to that of the FN. BSI precision error was about 3 times higher compared to BMD, confirming previous results of lumbar spine BSI. The main source of variability of this new software is related to patient positioning.