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1. Guidelines for the assessment of bone density and microarchitecture in vivo using high-resolution peripheral quantitative computed tomography.

Author

Whittier, D, Boyd, S, Paccou, J, Ghasem-Zadeh, A, Chapurlat, R, Engelke, K, Bouxsein, M, and Burghardt, Andrew

Subjects
Bone microarchitecture, Guidelines, High-resolution peripheral quantitative computed tomography, Imaging protocol, Bone Density, Humans, Osteoporosis, Radius, Tibia, Tomography, X-Ray Computed
Abstract

INTRODUCTION: The application of high-resolution peripheral quantitative computed tomography (HR-pQCT) to assess bone microarchitecture has grown rapidly since its introduction in 2005. As the use of HR-pQCT for clinical research continues to grow, there is an urgent need to form a consensus on imaging and analysis methodologies so that studies can be appropriately compared. In addition, with the recent introduction of the second-generation HrpQCT, which differs from the first-generation HR-pQCT in scan region, resolution, and morphological measurement techniques, there is a need for guidelines on appropriate reporting of results and considerations as the field adopts newer systems. METHODS: A joint working group between the International Osteoporosis Foundation, American Society of Bone and Mineral Research, and European Calcified Tissue Society convened in person and by teleconference over several years to produce the guidelines and recommendations presented in this document. RESULTS: An overview and discussion is provided for (1) standardized protocol for imaging distal radius and tibia sites using HR-pQCT, with the importance of quality control and operator training discussed; (2) standardized terminology and recommendations on reporting results; (3) factors influencing accuracy and precision error, with considerations for longitudinal and multi-center study designs; and finally (4) comparison between scanner generations and other high-resolution CT systems. CONCLUSION: This article addresses the need for standardization of HR-pQCT imaging techniques and terminology, provides guidance on interpretation and reporting of results, and discusses unresolved issues in the field.

Published
2020

4. Operator variability in scan positioning is a major component of HR-pQCT precision error and is reduced by standardized training.

Author

Bonaretti, S, Vilayphiou, N, Chan, C, Yu, A, Nishiyama, K, Liu, D, Boutroy, S, Ghasem-Zadeh, A, Boyd, S, Chapurlat, R, McKay, H, Shane, E, Bouxsein, M, Orwoll, E, Khosla, S, Black, Dennis, Majumdar, Sharmila, Lang, Thomas, and Burghardt, Andrew

Subjects
HR-pQCT, Multicenter studies, Operator reproducibility, Precision, Standardization, Aged, Aged, 80 and over, Anatomic Landmarks, Clinical Competence, Female, Humans, Inservice Training, Male, Osteoporosis, Radius, Reproducibility of Results, Software Design, Tibia, Tomography, X-Ray Computed
Abstract

UNLABELLED: In this study, we determined that operator positioning precision contributes significant measurement error in high-resolution peripheral quantitative computed tomography (HR-pQCT). Moreover, we developed software to quantify intra- and inter-operator variability and demonstrated that standard positioning training (now available as a web-based application) can significantly reduce inter-operator variability. INTRODUCTION: HR-pQCT is increasingly used to assess bone quality, fracture risk, and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection (scout view image) and define the region to be scanned by positioning a reference line on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. METHODS: To evaluate the operator in vivo measurement precision, we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanners software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled six new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. RESULTS: In vivo precision errors were up to threefold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. The inter-operator precision errors were significantly greater than the short-term intra-operator precision (p

Published
2017

35. Retrospective Study of Serum Sclerostin Measurements in Bed Rest Subjects

Author

Spatz, J. M, Fields, E. E, Yu, E. W, Divieti, Pajevic P, Bouxsein, M. L, Sibonga, M. L, Zwart, S. R, and Smith, S. M

Subjects
Aerospace Medicine
Abstract

Animal models and human studies suggest that osteocytes regulate the skeleton s response to mechanical unloading at the cellular level in part by an increase in sclerostin, an inhibitor of the anabolic Wnt pathway. However, few studies have reported changes in serum sclerostin in humans exposed to reduced mechanical loading. Thus, we determined changes in serum sclerostin and bone turnover markers in healthy adult men who participated in a controlled bed rest study. Seven healthy adult men (31 +/- 3 yrs old) underwent 90-day six-degree head down tilt bed rest at the University of Texas Medical Branch in Galveston's Institute for Translational Sciences - Clinical Research Center (ITS-CRC). Serum sclerostin, PTH, serum markers of bone turnover (bone specific alkaline phosphatase, RANKL/OPG, and osteocalcin), urinary calcium and phosphorus excretion, and 24 hour pooled urinary markers of bone resorption (NTX, DPD, PYD) were evaluated pre-bed rest (BL), bed rest day 28 (BR-28), bed rest day 60 (BR-60), and bed rest day 90 (BR-90). In addition, bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry (DXA) at BL, BR-60, and post bed rest day 5 (BR+5). Data are reported as mean +/- standard deviation. We used repeated measures ANOVA to compare baseline values to BR-28, BR-60, and BR-90. RESULTS Consistent with prior reports, BMD declined significantly (1-2% per month) at weight-bearing skeletal sites (spine, hip, femur neck, and calcaneus). Serum sclerostin levels were elevated above BL at BR-28 (+29% +/- 20%, p = 0.003), BR-60 (+42% +/- 31%, p < 0.001), and BR-90 (22% +/- 21%, p = 0.07). Serum PTH levels were reduced at BR-28 (-17% +/- 16%, p = 0.02), BR-60 (-24% +/- 14%, p = 0.03), and returned to baseline at BR-90 (-21% +/- 21%, p = 0.14). Serum bone turnover markers did not change, however urinary bone resorption markers and calcium were significantly elevated following bed rest (p < 0.01). CONCLUSION We observed an increase of serum sclerostin associated with decreased serum PTH and elevated bone resorption markers in otherwise healthy men subjected to long-term immobilization.

Published
2011

37. Data Mining Activity for Bone Discipline: Calculating a Factor of Risk for Hip Fracture in Long-Duration Astronauts

Author

Ellman, R, Sibonga, J. D, and Bouxsein, M. L

Subjects
Aerospace Medicine
Abstract

The factor-of-risk (Phi), defined as the ratio of applied load to bone strength, is a biomechanical approach to hip fracture risk assessment that may be used to identify subjects who are at increased risk for fracture. The purpose of this project was to calculate the factor of risk in long duration astronauts after return from a mission on the International Space Station (ISS), which is typically 6 months in duration. The load applied to the hip was calculated for a sideways fall from standing height based on the individual height and weight of the astronauts. The soft tissue thickness overlying the greater trochanter was measured from the DXA whole body scans and used to estimate attenuation of the impact force provided by soft tissues overlying the hip. Femoral strength was estimated from femoral areal bone mineral density (aBMD) measurements by dual-energy x-ray absorptiometry (DXA), which were performed between 5-32 days of landing. All long-duration NASA astronauts from Expedition 1 to 18 were included in this study, where repeat flyers were treated as separate subjects. Male astronauts (n=20) had a significantly higher factor of risk for hip fracture Phi than females (n=5), with preflight values of 0.83+/-0.11 and 0.36+/-0.07, respectively, but there was no significant difference between preflight and postflight Phi (Figure 1). Femoral aBMD measurements were not found to be significantly different between men and women. Three men and no women exceeded the theoretical fracture threshold of Phi=1 immediately postflight, indicating that they would likely suffer a hip fracture if they were to experience a sideways fall with impact to the greater trochanter. These data suggest that male astronauts may be at greater risk for hip fracture than women following spaceflight, primarily due to relatively less soft tissue thickness and subsequently greater impact force.

Published
2010

39. Perspectives on the non-invasive evaluation of femoral strength in the assessment of hip fracture risk

Author

Bouxsein, M. L., Zysset, P., Glüer, C. C., McClung, M., Biver, Emmanuel, Pierroz, D.D., Ferrari, Serge Livio, and IOF Working Group on Hip Bone Strength as a Therapeutic Target

Subjects
0301 basic medicine, musculoskeletal diseases, Male, medicine.medical_specialty, Endocrinology, Diabetes and Metabolism, Osteoporosis, Finite Element Analysis, 030209 endocrinology & metabolism, Bone strength, Bone tissue, Hip fracture, 03 medical and health sciences, 0302 clinical medicine, Absorptiometry, Photon, Bone Density, medicine, Humans, Femur, Pelvic Bones, Aged, Orthodontics, Bone mineral, ddc:616, Surrogate endpoint, business.industry, Hip Fractures, Finite element analysis (FEA), medicine.disease, musculoskeletal system, medicine.anatomical_structure, Hip bone, Case-Control Studies, Orthopedic surgery, Fracture (geology), Female, 030101 anatomy & morphology, business, Bone mineral density (BMD)
Abstract

We reviewed the experimental and clinical evidence that hip bone strength estimated by BMD and/or finite element analysis (FEA) reflects the actual strength of the proximal femur and is associated with hip fracture risk and its changes upon treatment. The risk of hip fractures increases exponentially with age due to a progressive loss of bone mass, deterioration of bone structure, and increased incidence of falls. Areal bone mineral density (aBMD), measured by dual-energy X-ray absorptiometry (DXA), is the most used surrogate marker of bone strength. However, age-related declines in bone strength exceed those of aBMD, and the majority of fractures occur in those who are not identified as osteoporotic by BMD testing. With hip fracture incidence increasing worldwide, the development of accurate methods to estimate bone strength in vivo would be very useful to predict the risk of hip fracture and to monitor the effects of osteoporosis therapies. We reviewed experimental and clinical evidence regarding the association between aBMD and/orCT-finite element analysis (FEA) estimated femoral strength and hip fracture risk as well as their changes with treatment. Femoral aBMD and bone strength estimates by CT-FEA explain a large proportion of femoral strength ex vivo and predict hip fracture risk in vivo. Changes in femoral aBMD are strongly associated with anti-fracture efficacy of osteoporosis treatments, though comparable data for FEA are currently not available. Hip aBMD and estimated femoral strength are good predictors of fracture risk and could potentially be used as surrogate endpoints for fracture in clinical trials. Further improvements of FEA may be achieved by incorporating trabecular orientations, enhanced cortical modeling, effects of aging on bone tissue ductility, and multiple sideway fall loading conditions.

Published
2019

47. Treatment-Related Changes in Bone Turnover and Fracture Risk Reduction in Clinical Trials of Anti-Resorptive Drugs: A Meta-Regression

Author

Bauer, D., Black, D., Bouxsein, M., Lui, L.-Y., Cauley, J., de Papp, A., Grauer, A., Khosla, S., McCulloch, C., Eastell, R., and Foundation for the National Institutes of Health (FNIH) Bone Qua, The.

Abstract

Few pooled analyses of antiresorptive (AR) treatment trials relate short-term changes in bone turnover markers (BTMs) to subsequent fracture reduction. Such information would be useful to assess new ARs or novel dosing regimens. In the Foundation for the National Institutes of Health (FNIH) Bone Quality project, we analyzed individual-level data from 28,000 participants enrolled in 11 bisphosphonate (BP) and three selective estrogen receptor modulator (SERM) placebo-controlled fracture endpoint trials. Using BTM results for two bone formation markers (bone-specific alkaline phosphatase [bone ALP] and pro-collagen I N-propeptide [PINP]) and two bone resorption markers (N-terminal and C-terminal telopeptide of type I collagen) and incident fracture outcome data, we performed a meta-regression relating the mean net effect of treatment on change in bone turnover (active minus placebo % difference after 3 to 12 months) to the log of study-wide fracture risk reduction, and used linear regression to plot the best fitting line. Separate analyses were performed for incident morphometric vertebral, nonvertebral, and hip fractures over 1 to 4 years of follow-up. Change in bone ALP and PINP were available for over 16,000 and 10,000 participants, respectively. For vertebral fracture, the results showed a strong relationship between treatment-related bone ALP or PINP changes and vertebral fracture risk reduction (r2 = 0.82 [p

Published
2018

50. Subtrochanteric fractures after long-term treatment with bisphosphonates: a European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis, and International Osteoporosis Foundation Working Group Report

Author

Rizzoli, R., Åkesson, K., Bouxsein, M., Kanis, J., Napoli, N., Papapoulos, S., Reginster, J.-Y, Cooper, C., Rizzoli, R., Åkesson, K., Bouxsein, M., Kanis, J., Napoli, N., Papapoulos, S., Reginster, J.-Y, and Cooper, C.

Abstract

Summary: This paper reviews the evidence for an association between atypical subtrochanteric fractures and long-term bisphosphonate use. Clinical case reports/reviews and case-control studies report this association, but retrospective phase III trial analyses show no increased risk. Bisphosphonate use may be associated with atypical subtrochanteric fractures, but the case is yet unproven. Introduction: A Working Group of the European Society on Clinical and Economic Aspects of Osteoporosis and Osteoarthritis and the International Osteoporosis Foundation has reviewed the evidence for a causal association between subtrochanteric fractures and long-term treatment with bisphosphonates, with the aim of identifying areas for further research and providing recommendations for physicians. Methods: A PubMed search of literature from 1994 to May 2010 was performed using key search terms, and articles pertinent to subtrochanteric fractures following bisphosphonate use were analysed. Results: Several clinical case reports and case reviews report a possible association between atypical fractures at the subtrochanteric region of the femur in bisphosphonate-treated patients. Common features of these ‘atypical' fractures include prodromal pain, occurrence with minimal/no trauma, a thickened diaphyseal cortex and transverse fracture pattern. Some small case-control studies report the same association, but a large register-based study and retrospective analyses of phase III trials of bisphosphonates do not show an increased risk of subtrochanteric fractures with bisphosphonate use. The number of atypical subtrochanteric fractures in association with bisphosphonates is an estimated one per 1,000 per year. It is recommended that physicians remain vigilant in assessing their patients treated with bisphosphonates for the treatment or prevention of osteoporosis and advise patients of the potential risks. Conclusions: Bisphosphonate use may be associated with atypical subtrochanteric fract

Published
2018

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