Bone structure and fracture risk: do they go arm in arm?

Applying ethnic-specific bone mineral density T-scores to Chinese women in the USA

Caucasian reference data are used to classify bone mineral density in US women of all races. However, use of Chinese American reference data yields lower osteoporosis prevalence in Chinese women. The reduction in osteoporosis labeling may be relevant for younger Chinese women at low fracture risk.

INTRODUCTION

Caucasian reference data are used for osteoporosis classification in US postmenopausal women regardless of race, including Asians who tend to have lower bone mineral density (BMD) than women of white race. This study examines BMD classification by ethnic T-scores for Chinese women.

METHODS

Using BMD data in a Northern California healthcare population, Chinese women aged 50-79 years were compared to age-matched white women (1:5 ratio), with femoral neck (FN), total hip (TH), and lumbar spine (LS) T-scores calculated using Caucasian versus Chinese American reference data.

RESULTS

Comparing 4039 Chinese and 20,195 white women (44.8 % age 50-59 years, 37.5 % age 60-69 years, 17.7 % age 70-79 years), Chinese women had lower BMD T-scores at the FN, TH, and LS (median T-score 0.29-0.72 units lower across age groups, p < 0.001) using Caucasian reference data. Using Chinese American BMD reference data resulted in an average +0.47, +0.36, and +0.48 units higher FN, TH, and LS T-scores, respectively, reducing the prevalence of osteoporosis (T-score ≤ -2.5) in Chinese women at the FN (16.7 to 6.6 %), TH (9.8 to 3.2 %), and LS (23.2 to 8.9 %); osteoporosis prevalence at any one of three sites fell from 29.6 to 12.6 % (22.4 to 8.1 % for age 50-64 years and 43.2 to 21.0 % for age 65-79 years).

CONCLUSION

Use of Chinese American BMD reference data yields higher (ethnic) T-scores by 0.4-0.5 units, with a large proportion of Chinese women reclassified from osteoporosis to osteopenia. The reduction in osteoporosis labeling with ethnic T-scores may be relevant for younger Chinese women at low fracture risk.

Ethnic differences in bone health

There are differences in bone health between ethnic groups in both men and in women. Variations in body size and composition are likely to contribute to reported differences. Most studies report ethnic differences in areal bone mineral density (aBMD), which do not consistently parallel ethnic patterns in fracture rates. This suggests that other parameters beside aBMD should be considered when determining fracture risk between and within populations, including other aspects of bone strength: bone structure and microarchitecture, as well as muscle strength (mass, force generation, anatomy) and fat mass. We review what is known about differences in bone-densitometry-derived outcomes between ethnic groups and the extent to which they account for the differences in fracture risk. Studies are included that were published primarily between 1994 and 2014. A "one size fits all approach" should definitely not be used to understand better ethnic differences in fracture risk.

Quantitative computer tomography in children and adolescents: the 2013 ISCD Pediatric Official Positions

In 2007, International Society of Clinical Densitometry Pediatric Positions Task Forces reviewed the evidence for the clinical application of peripheral quantitative computed tomography (pQCT) in children and adolescents. At that time, numerous limitations regarding the clinical application of pQCT were identified, although its use as a research modality for investigation of bone strength was highlighted. The present report provides an updated review of evidence for the clinical application of pQCT, as well as additional reviews of whole body QCT scans of the central and peripheral skeletons, and high-resolution pQCT in children. Although these techniques remain in the domain of research, this report summarizes the recent literature and evidence of the clinical applicability and offers general recommendations regarding the use of these modalities in pediatric bone health assessment.

Bone, sweet bone--osteoporotic fractures in diabetes mellitus

Diabetes mellitus adversely affects the skeleton and is associated with an increased risk of osteoporosis and fragility fractures. The mechanisms underlying low bone strength are not fully understood but could include impaired accrual of peak bone mass and diabetic complications, such as nephropathy. Type 1 diabetes mellitus (T1DM) affects the skeleton more severely than type 2 diabetes mellitus (T2DM), probably because of the lack of the bone anabolic actions of insulin and other pancreatic hormones. Bone mass can remain high in patients with T2DM, but it does not protect against fractures, as bone quality is impaired. The class of oral antidiabetic drugs known as glitazones can promote bone loss and osteoporotic fractures in postmenopausal women and, therefore, should be avoided if osteoporosis is diagnosed. A physically active, healthy lifestyle and prevention of diabetic complications, along with calcium and vitamin D repletion, represent the mainstay of therapy for osteoporosis in patients with T1DM or T2DM. Assessment of BMD and other risk factors as part of the diagnostic procedure can help design tailored treatment plans. All osteoporosis drugs seem to be effective in patients with diabetes mellitus. Increased awareness of osteoporosis is needed in view of the growing and aging population of patients with diabetes mellitus.

X-ray diffraction as a promising tool to characterize bone nanocomposites

To understand the characteristics of bone at the tissue level, the structure, organization and mechanical properties of the underlying levels down to the nanoscale as well as their mutual interactions need to be investigated. Such information would help understand changes in the bone properties including stiffness, strength and toughness and provide ways to assess the aged and diseased bones and the development of next generation of bio-inspired materials. X-ray diffraction techniques have gained increased interest in recent years as useful non-destructive tools for investigating the nanostructure of bone. This review provides an overview on the recent progress in this field and briefly introduces the related experimental approach. The application of x-ray diffraction to elucidating the structural and mechanical properties of mineral crystals in bone is reviewed in terms of characterization of in situ strain, residual stress-strain and crystal orientation.