Peripheral quantitative computed tomography (pQCT) measures are associated with prior low trauma fracture in men

Peripheral quantitative computed tomography (pQCT) assesses bone quantity and quality, complementary to current standard practice, and has potential to improve prediction of fracture risk. This study explored whether pQCT parameters were associated with prior fracture in men and found a number of parameters to be associated, particularly at the radius.

PURPOSE

Peripheral quantitative computed tomography (pQCT) provides information about bone structure and density complementary to dual x-ray absorptiometry. This study aimed to determine which pQCT parameters are associated with prior fracture.

METHODS

Participants were men (n = 508, age 33-96 years) from the Geelong Osteoporosis Study. Parameters at 4% (n = 469) and 66% (n = 436) of radial length, and 4% (n = 449) and 66% (n = 437) of tibial length were acquired (pQCT XCT 2000, Stratec Medizintechnik, Pforzheim, Germany), and mean standardised. Low trauma prior fractures in adulthood (≥ age 20 years) were radiologically confirmed when possible. Cross-sectional associations between pQCT and fracture were tested using logistic regression adjusting for confounders.

RESULTS

Prior low trauma fractures were identified for 106 participants. Fracture was negatively associated with parameters at the 4% radius site: bone mass (adjusted OR = 0.67; 95%CI = 0.52-0.86), total density (OR = 0.61; 95%CI = 0.47-0.78), trabecular density (OR = 0.62; 95%CI = 0.48-0.79) and cortical subdensity (OR = 0.61; 95%CI = 0.47-0.77). At the 66% radius site, fracture was associated with total density (OR = 0.69; 95%CI = 0.55-0.87) and cortical thickness (OR = 0.68; 95%CI = 0.54-0.86). Fracture was associated with the ratio of the cortical area at the 66% site to the total area at the 4% site (OR = 0.74; 95%CI = 0.58-0.94). Prior fracture was negatively associated with parameters at the 4% tibial site: total density (OR = 0.67; 95%CI = 0.52-0.86), trabecular density (OR = 0.64; 95%CI = 0.50-0.82) and cortical subdensity (OR = 0.72; 95%CI = 0.56-0.92). Fracture was negatively associated with cortical density at the 66% site (OR = 0.74; 95%CI = 0.58-0.94), and the ratio of the cortical area at the 66% site to the total area at the 4% site (OR = 0.65; 95%CI = 0.46-0.91), but were attenuated in adjusted models. No other associations were identified.

CONCLUSION

Prior fracture was associated with parameters at both the radius and tibia. This study highlights key pQCT parameters that may aid in the prediction of fracture risk.

Normative data for peripheral quantitative computed tomography (pQCT) bone parameters in Australian men

Background

Peripheral quantitative computed tomography (pQCT) can provide information complementary to dual x-ray absorptiometry (DXA), however, there is sparse normative data to enable meaningful clinical interpretation and comparison. This study aimed to develop age-stratified normative data for pQCT-derived bone parameters in Australian men.

Methods

Participants were men (n = 508, age 33-96 yr) from the Geelong Osteoporosis Study. Bone parameters at 4% (n = 469) and 66% (n = 436) of radial length, and 4% (n = 449) and 66% (n = 438) of tibial length were acquired using pQCT (XCT 2000, Stratec Medizintechnik, Pforzheim, Germany). Best models of age, height and weight for each parameter were developed and where parameters exhibited variation with age, age decade mean (±SD) values were determined. Scatterplots were used to visualise the relationships between each of the parameters and age, height and weight.

Results

Thirteen parameters at tibial and radial sites were correlated with age, height and weight, allowing for their inclusion in multiple linear regression models. A positive association with age was found for total area of the tibia or radius (as appropriate) (mm²) at all sites, trabecular bone area (mm²) at 4% sites, and total bone area (both long bones) (mm²) at 66% sites. A negative association with age was found for cortical density (mg/cm³) and cortical thickness (mm) at both radial and tibial 66% sites, but total density (mg/cm³) at the 66% radial site and total cortical density of both long bones (mg/cm³) at the 66% tibial site only.

Conclusion

This study presents normative data for pQCT-derived bone parameters and describes age related associations in a number of these variables. Broadly, parameters of bone area were positively associated with age, whereas parameters associated with bone density and structure were negatively associated with age. These data have the potential to be used in clinical settings when assessing age-related decline in bone health.

Mini abstract

Normative data for pQCT parameters in Australian men are presented, adjusted for age, height and weight.

Relationship of cardiometabolic risk biomarkers with DXA and pQCT bone health outcomes in young girls

BACKGROUND

Excess weight exerts the positive effect of mechanical loading on bone during development whereas obesity-related metabolic dysfunction may have a detrimental impact. In adults, the presence of metabolic syndrome and type 2 diabetes has been associated with compromised bone density, quality, and strength, and an increased incidence of fractures. The few studies that have investigated the role of cardio-metabolic disease risk biomarkers (CMR) on bone strength in children have given conflicting results. The aim of this study was to assess the combined and independent relationships of cardio-metabolic biomarkers with total body and regional bone parameters in young girls.

METHODS

In 306, 9-12 year old girls, measures of whole body fat and lean mass, areal bone mineral density (aBMD), bone mineral content (BMC), and bone area (BA) were obtained by dual-energy x-ray absorptiometry (DXA). Bone mineral density (vBMD), geometry, and strength of metaphyseal and diaphyseal regions of the femur and tibia and a diaphyseal region of the radius were measured using peripheral quantitative computed tomography (pQCT). Fasting serum measures of CMRs included, fasting glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), high-density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride (TG), systolic and diastolic blood pressure (SBP and DBP), and C-reactive protein (CRP). Multiple linear regression was used to assess the independent associations of a single CMR with total body and peripheral measures of bone strength after controlling for the other CMRs, plus total body soft tissue, and other relevant covariates. Also, a standardized total CMR composite score, calculated by standardizing to z-scores and then summing z-scores of each CMR biomarker, was regressed with total body and regional bone measures to assess the relationship of a cluster of risk factors with bone health.

RESULTS

Total CMR composite score had inverse associations (p < 0.001) with DXA total BMC and BA. Inverse associations (p < 0.05) of CMR risk score with pQCT regional bone measures occurred with total and trabecular BA at the 4% tibia. Of the individual CMRs, HOMA-IR and CRP were significant predictors of total body bone measures by DXA accounting for ~1-5% of the variance in BMC, BA, and/or aBMD. HOMA-IR was the main predictor of regional pQCT bone outcomes, accounting for the most variance in trabecular vBMD (2.6%) and BSI (3.8%) at the 4% tibia. Most markers of dyslipidemia (TG, HDL-C, LDL-C) and hypertension (SBP, DBP) were not associated (p > 0.05) with any total body or regional bone outcomes with the exception of the inverse relationship of LDL-C with total and trabecular BA and the positive relationship of DBP with cortical vBMD at the radius.

CONCLUSION

Of the obesity-related metabolic impairments, insulin resistance and chronic inflammation may compromise whole body bone development in young girls. In particular, trabecular bone, such as that found at the metaphysis of long bones, may be more susceptible to the detrimental effects associated with obesity-related metabolic dysfunction.

Longitudinal Change in Peripheral Quantitative Computed Tomography Assessment in Older Adults: The Hertfordshire Cohort Study

There are few longitudinal data on change in bone structure and muscle mass, strength and function in later life. We report these, and consider bone-muscle interrelationships in older men and women. We studied 188 men and 166 women from the Hertfordshire Cohort Study, who underwent peripheral quantitative computed tomography (pQCT) of the radius and tibia in 2004-2005 and then again in 2011-2012. Grip strength and gait speed were also assessed at both timepoints. Percentage change per year was calculated for grip strength, gait speed, muscle cross-sectional area (mCSA), fat cross-sectional area (fCSA) and diaphyseal bone parameters [total area (Tt.Ar), cortical area (Ct.Ar), cortical density (cBMD) and trabecular density (tBMD)]. The mean (SD) age of men and women at baseline was 68.9 (2.5) and 69.2 (2.6) years, respectively. Rates of muscle area and strength loss did not differ by sex. Tt.Ar increased with age and faster in men [mean (SD) 1.78 (1.64) %/year] than women [mean (SD) 1.03 (1.69) %/year] in the radius (p < 0.001). In both the radius (p = 0.006) and tibia (p < 0.001), Ct.Ar reduced more rapidly in women than men. Change in Ct.Ar was associated with change in muscle area in the corresponding limb (radius; men: regression coefficient 0.36, 95% CI 0.20-0.52, p < 0.001; tibia; men: regression coefficient 0.14, 95% CI 0.00-0.27, p = 0.043, women: regression coefficient 0.16, 95% CI 0.01-0.30, p = 0.032). We have demonstrated that muscle strength and function decrease faster than muscle mass and have provided further evidence that changes in bone structure with age differ by sex.

Type 2 diabetes is associated with higher trabecular bone density but lower cortical bone density: the Vietnam Osteoporosis Study

It is not clear why type 2 diabetes (T2D) has an increased risk of fracture despite higher areal bone mineral density. This study showed that compared with controls, T2D patients had higher trabecular bone density but lower cortical bone density, resulting in a lower bone strength.

INTRODUCTION

To define the association between type 2 diabetes and bone architecture and measures of bone strength.

METHODS

The study was part of the Vietnam Osteoporosis Study, in which 1115 women and 614 men aged ≥ 30 were randomly recruited from Ho Chi Minh City. HbA_1c levels were measured with analyzers ADAMS™ A_1c HA-8160 (Arkray, Kyoto, Japan). The diagnosis of T2D was made if HbA1c was ≥ 6.5%. Trabecular and cortical volumetric bone density (vBMD) was measured in the forearm and leg by a pQCT XCT2000 (Stratec, Germany). Polar stress strain index (pSSI) was derived from the pQCT measurements. Difference in bone parameters between T2D and non-diabetic individuals was assessed by the number of standard deviations (effect size [ES]) by the propensity score analysis.

RESULTS

The prevalence of T2D was ~ 8%. The results of propensity score matching for age, sex, and body mass index in 137 pairs of diabetic and non-diabetic individuals showed that T2D patients had significantly higher distal radius trabecular vBMD (ES 0.26; 95% CI, 0.02 to 0.50), but lower cortical vBMD (ES - 0.22; - 0.46 to 0.00) and reduced pSSI (ES - 0.23; - 0.47 to - 0.02) compared with non-diabetic individuals. Multiple linear regression analysis based on the entire sample confirmed the results of the propensity score analysis.

CONCLUSION

Compared with non-diabetic individuals, patients with T2D have greater trabecular but lower cortical vBMD which leads to lower bone strength.

Relative contributions of lean and fat mass to bone strength in young Hispanic and non-Hispanic girls

BACKGROUND

With the high prevalence of childhood obesity, especially among Hispanic children, understanding how body weight and its components of lean and fat mass affect bone development is important, given that the amount of bone mineral accrued during childhood can determine osteoporosis risk later in life. The aim of this study was to assess the independent contributions of lean and fat mass on volumetric bone mineral density (vBMD), geometry, and strength in both weight-bearing and non-weight-bearing bones of Hispanic and non-Hispanic girls.

METHODS

Bone vBMD, geometry, and strength were assessed at the 20% distal femur, the 4% and 66% distal tibia, and the 66% distal radius of the non-dominant limb of 326, 9- to 12-year-old girls using peripheral quantitative computed tomography (pQCT). Total body lean and fat mass were measured by dual-energy x-ray absorptiometry (DXA). Multiple linear regression was used to assess the independent relationships of fat and lean mass with pQCT bone measures while adjusting for relevant confounders. Potential interactions between ethnicity and both fat and lean mass were also tested.

RESULTS

Lean mass was a significant positive contributor to all bone outcomes (p < 0.05) with the exception of vBMD at diaphyseal sites. Fat mass was a significant contributor to bone strength at weight bearing sites, but did not significantly contribute to bone strength at the non-weight bearing radius and was negatively associated with radius cortical content and thickness. Bone measures did not significantly differ between Hispanic and non-Hispanic girls, although there was a significant interaction between ethnicity and fat mass with total bone area at the femur (p = 0.02) and 66% tibia (p = 0.005) as well as bone strength at the femur (p = 0.03).

CONCLUSION

Lean mass is the main determinant of bone strength for appendicular skeletal sites. Fat mass contributes to bone strength in the weight-bearing skeleton but does not add to bone strength in non-weight-bearing locations and may potentially be detrimental. Bone vBMD, geometry, and strength did not differ between Hispanic and non-Hispanic girls; fat mass may be a stronger contributor to bone strength in weight-bearing bones of Hispanic girls compared to non-Hispanic.

Higher step count is associated with greater bone mass and strength in women but not in men

In this cross-sectional study, peripheral bone traits were examined relative to total daily steps measured with pedometer. Higher number of steps was associated with greater bone values at the calcaneus and tibia in women, but not in men. In women, dose-dependent associations at the radius were congruent with the weight-bearing bones.

INTRODUCTION

Habitual physical activity measured as daily steps may contribute to bone density and strength at the calcaneus and other weight-bearing bones.

METHODS

Subgroups of 705-837 women and 480-615 men aged 31-46 years from the Cardiovascular Risk in Young Finns Study participated in the present study. Participants were instructed to use pedometer for 1 week, and the total daily steps, divided into tertiles, were evaluated relative to quantitative ultrasound-measured bone traits at the calcaneus and peripheral quantitative computed tomography-measured bone traits at the tibia and radius. Analysis of covariance was used to examine the between-group differences.

RESULTS

In women, significant dose-dependent between-group differences were found in the weight-bearing bones and in non-weight-bearing radius. The differences in broadband ultrasound attenuation and speed of sound at the calcaneus were 3.8 and 0.5% greater in women within the highest tertile of daily steps compared to the lowest tertile (p values for trend ≤ 0.04). In tibia, women in the highest tertile (> 8765 steps/day) had on average 1-5.4% greater bone cross-sectional area, bone mineral content (BMC), trabecular density, and bone strength index at the distal site and 1.6-2.7% greater bone areas, BMC and strength strain index (SSI) at the shaft compared to women with less daily steps (p values for trend ≤ 0.02). Similarly, in radius, BMC and BSI at the distal site, and bone cross-sectional areas, BMC and SSI at the shaft were 1.7-3.4% greater in women within the highest tertile of daily steps compared to their peers (p values for trend ≤ 0.04). In men, the differences in calcaneal, tibial, and radial bone traits were mainly non-significant between the tertiles of daily steps.

CONCLUSION

Observed significant positive associations between daily steps and various bone traits at the calcaneus, tibia, and radius in women suggest that habitual physical activity may benefit skeletal health in adulthood.

Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history

PURPOSE

To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture.

METHODS

We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm³), total (ToA) and cortical (CtA) bone areas (mm²), and estimated compressive bone strength (bone strength index; BSI, mg/mm⁴) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm³ and strength strain index; SSIp, mm³) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm²/N∗kg^-1) at all cortical sites.

RESULTS

SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (p<0.05).

CONCLUSION

These findings indicate that estimated bone strength at the mid-tibia and mean pkZ GRFs are lower in runners with a history of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture.

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional 'muscle-bone unit', defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton's health follow-up.

Bone strength and muscle properties in postmenopausal women with and without a recent distal radius fracture

Distal radius (wrist) fracture (DRF) in women over age 50 years is an early sign of bone fragility. Women with a recent DRF compared to women without DRF demonstrated lower bone strength, muscle density, and strength, but no difference in dual-energy x-ray absorptiometry (DXA) measures, suggesting DXA alone may not be a sufficient predictor for DRF risk.

INTRODUCTION

The objective of this study was to investigate differences in bone and muscle properties between women with and without a recent DRF.

METHODS

One hundred sixty-six postmenopausal women (50-78 years) were recruited. Participants were excluded if they had taken bone-altering medications in the past 6 months or had medical conditions that severely affected daily living or the upper extremity. Seventy-seven age-matched women with a fracture in the past 6-24 months (Fx, n = 32) and without fracture (NFx, n = 45) were measured for bone and muscle properties using the nondominant (NFx) or non-fractured limb (Fx). Peripheral quantitative computed tomography (pQCT) was used to estimate bone strength in compression (BSIc) at the distal radius and tibia, bone strength in torsion (SSIp) at the shaft sites, muscle density, and area at the forearm and lower leg. Areal bone mineral density at the ultradistal forearm, spine, and femoral neck was measured by DXA. Grip strength and the 30-s chair stand test were used as estimates of upper and lower extremity muscle strength. Limb-specific between-group differences were compared using multivariate analysis of variance (MANOVA).

RESULTS

There was a significant group difference (p < 0.05) for the forearm and lower leg, with the Fx group demonstrating 16 and 19% lower BSIc, 3 and 6% lower muscle density, and 20 and 21% lower muscle strength at the upper and lower extremities, respectively. There were no differences between groups for DXA measures.

CONCLUSIONS

Women with recent DRF had lower pQCT-derived estimated bone strength at the distal radius and tibia and lower muscle density and strength at both extremities.

Alterations in bone mineral density and lower extremity lean mass after hip arthroscopy in a professional female Ironman triathlete: a case study

Introduction

Femoroacetabular impingement is a pathomechanical condition of the hip, which is often treated through arthroscopic techniques. The ensuing immobilization period is associated with decreases in muscle mass and bone mass. To date, minimal knowledge is present about the development of tissue mass during the considerably short rehabilitation period before returning to competition in elite endurance athletes.

Case description

Before and after surgery, a professional female Ironman triathlete underwent dual-energy X-ray absorptiometry and peripheral quantitative computed tomography measurements.

Discussion and evaluation

Areal bone mineral density (aBMD) of the proximal femur and lower extremity lean mass decreased in the surgically treated lower extremity during the two-month period of immobilization after the hip arthroscopy. These losses were compensated for after only six weeks of rehabilitation. A similar progression of aBMD values was observed in the lumbar spine. The adaptational pattern in volumetric BMD (vBMD) and volumetric bone mineral content (vBMC) of the tibiae were more complex, but attained pre-immobilization values for most variables also after six weeks of rehabilitation. All other variables attained pre-immobilization values no later than nine months after the surgical intervention.

Conclusions

The athlete showed a high plasticity of bone and lean tissue with an optimal short- and midterm outcome. Following a two months immobilization period after a hip arthroscopy, aBMD, vBMD and vBMC achieved pre-surgical levels after four months of rehabilitation in a female Ironman triathlete. A nine-month follow-up measurement confirmed the safety of the fast return to sport.

Relationship of total body fat mass to weight-bearing bone volumetric density, geometry, and strength in young girls

Understanding the influence of total body fat mass (TBFM) on bone during the peri-pubertal years is critical for the development of future interventions aimed at improving bone strength and reducing fracture risk. Thus, we evaluated the relationship of TBFM to volumetric bone mineral density (vBMD), geometry, and strength at metaphyseal and diaphyseal sites of the femur and tibia of young girls. Data from 396 girls aged 8-13 years from the "Jump-In: Building Better Bones" study were analyzed. Bone parameters were assessed using peripheral quantitative computed tomography (pQCT) at the 4% and 20% distal femur and 4% and 66% distal tibia of the non-dominant leg. Bone parameters at the 4% sites included trabecular vBMD, periosteal circumference, and bone strength index (BSI), while at the 20% femur and 66% tibia, parameters included cortical vBMD, periosteal circumference, and strength-strain index (SSI). Multiple linear regression analyses were used to assess associations between bone parameters and TBFM, controlling for muscle cross-sectional area (MCSA). Regression analyses were then repeated with maturity, bone length, physical activity, and ethnicity as additional covariates. Analysis of covariance (ANCOVA) was used to compare bone parameters among tertiles of TBFM. In regression models with TBFM and MCSA, associations between TBFM and bone parameters at all sites were not significant. TBFM explained very little variance in all bone parameters (0.2-2.3%). In contrast, MCSA was strongly related (p<0.001) to all bone parameters, except cortical vBMD. The addition of maturity, bone length, physical activity, and ethnicity did not alter the relationship between TBFM and bone parameters. With bone parameters expressed relative to total body mass, ANCOVA showed that all outcomes were significantly (p<0.001) greater in the lowest compared to the middle and highest tertiles of TBFM. Although TBFM is correlated with femur and tibia vBMD, periosteal circumference, and strength in young girls, this relationship is significantly attenuated after adjustment for MCSA. Nevertheless, girls with higher TBFM relative to body mass have markedly diminished vBMD, geometry, and bone strength at metaphyseal and diaphyseal sites of the femur and tibia.