pQCT Scans Research Articles

Changes in peripheral quantitative computed tomography measured bone density, size and strength in Zimbabwean children with and without HIV over one year: a cohort study.

Understanding bone accrual in adolescents may inform approaches to improve skeletal health and reduce adult fracture risk. We investigated the effect of HIV on bone mineral accrual assessed by peripheral Quantitative Computed tomography (pQCT). Children with HIV (CWH) on ART for ≥2years, and children without HIV (CWOH), aged 8-16years (n = 609), had tibial pQCT scans at 0 and 12months. Linear regression estimated sex stratified differences in change (∆) and mean pQCT bone density (trabecular and cortical), size (total cross-sectional area [CSA]) and strength (SSI) between CWH and CWOH, adjusting for socio-economic status (SES) and orphanhood and incorporating an interaction term for baseline pubertal status (Tanner 1-2[pre/early] vs 3-5[mid/late]). Structural equation modelling tested whether baseline height-for-age-Z-scores (HAZ) mediate the effect of HIV on ∆bone outcomes. CWH were more likely than CWOH to be orphans (44% vs 7%), of lower SES (43% vs 27%) and be stunted (30% vs 8%); but similar in age. At baseline and follow up, CWH had lower trabecular density, CSA and SSI than CWOH. After adjustment, bone density and strength increased similarly in CWH and CWOH. CWH in mid/late puberty at baseline had greater 12months increases in CSA than CWOH, particularly males (mean difference [31.3(95%CI:-3.1, 65.6) mm2 in mid/late puberty vs. -2.04(-23.8, 19.7) mm2 in pre/early puberty; interaction P-value = 0.013]. HAZ mediated the effect of HIV on ∆bone outcomes only in females as follows: indirect pathways from HIV to ∆trabecular density [-1.85(-3.5, -0.2) mg/cm3], ∆cortical density [-2.01(-3.9, -0.01) mg/cm3], ∆CSA [-2.59(-4.7, -0.5) mm] and ∆SSI [-18.36(-29.6, -7.2) mm3]. In conclusion, CWH show bone deficits at follow up. Investigations of bone mineral accrual earlier in life and post-puberty to peak bone mass are needed.

Deep learning in sex estimation from a peripheral quantitative computed tomography scan of the fourth lumbar vertebra—a proof-of-concept study

Sex estimation is a key element in the analysis of unknown skeletal remains. The vertebrae display clear sex discrepancy and have proven accurate in conventional morphometric sex estimation. This proof-of-concept study aimed to investigate the possibility to develop a deep learning algorithm for sex estimation even from a single peripheral quantitative computed tomography (pQCT) slice of the fourth lumbar vertebra (L4). The study utilized a total of 117 vertebrae from the Terry Anatomical Collection. There were 58 male and 59 female cadavers, all of the white ethnicity, with the average age at death 49 years and a range of 24 to 77 years. A coronal pQCT scan was taken from the midway of the L4 corpus. Sex estimation was performed in a total of 19 neural network architectures implemented in the AIDeveloper software. Of the explored architectures, a LeNet5-based algorithm reached the highest accuracy of 86.4% in the test set. Sex-specific classification rates were 90.9% among males and 81.8% among females. This preliminary finding advances the field by encouraging and directing future research on artificial intelligence-based methods in sex estimation from individual skeletal traits such as the vertebrae. Combining quickly obtained imaging data with automated deep learning algorithms may establish a valuable pipeline for forensic anthropology and provide aid when combined with traditional methods.

Ankle flexor torque, size and density are differential determinants of distal tibia trabecular plate-rod morphometry and bone strength: The Ankle Quality Study.

Greater peak torque and higher myotendinous density at the ankle are associated with a more plate-like architecture at the distal tibia. In this cross-sectional study, women and men ≥ 50years old with no metal implants, reconstructive surgery, muscular dystrophies, or tendinopathies in any leg were recruited by convenience. Isometric ankle dorsi-plantar flexion and inversion-eversion peak torques were measured using dynamometry. HR-pQCT distal tibia scans were completed. Both assessments were completed on the same day on the non-dominant leg. Integral and trabecular vBMD were derived from standard analyses, failure load (FL) was obtained from finite element analysis, plate-specific parameters were computed from individual trabecula segmentation (ITS) analysis, myotendinous density (MyD) and volume fraction (MyV/TV) were computed from soft tissue analysis. pQCT scans of the 66% mid-leg were performed (500μm at 15mm/s) to obtain muscle density (MD) and muscle cross-sectional area (MCSA). General linear models estimated how ankle muscle group torque and muscle size and density differentially related, both separately and together, to whole-bone properties (integral vBMD, FL) and trabecular morphometry (ITS plate parameters). Models were adjusted for age, sex, BMI, use of glucocorticoids, current osteoarthritis, and participation in moderate to vigorous recreational or sport activities. Among 105 participants (77% female, mean age: 63 (10) years, BMI: 25.8 (5.4) kg/m2, 25% with OA, 17% fracture history, 42% falls history), all torque measures, particularly ankle dorsiflexion and eversion, were correlates of plate-plate/rod junction density and failure load. However, muscle size and density measures were further associated with vBMD. The effect of greater ankle flexor-extensor torque on more connected bone was stronger when MyD was higher (interaction p<0.001). Strength of muscles around the ankle are correlates of plate-like trabeculae at the distal tibia, while leaner muscle and myotendinous tissues facilitates better quality bone for stronger ankle muscle torque.

External training load is associated with adaptation in bone and body composition over the course of a season in elite male footballers

This study examined the relationship between training load and changes in body composition and bone characteristics across a competitive season. Twenty senior male professional football players participated in this prospective longitudinal study. Participants underwent dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scans on four occasions across the study period, resulting in three phases of the season. Phase 1 (Scan 1-Scan 2: 6-weeks: pre-season), Phase 2 (Scan 2-Scan 3: 24-weeks: first part of the season), and Phase 3 (Scan 3-Scan 4: 13-weeks: second part of the season). External training load was quantified using GPS devices. In Phase 1 there was a significant increase (mean ± SE) in lean mass (from 66.0 ± 1.4 to 67.8 ± 1.4 kg) and a significant decrease in fat mass (from 11.5 ± 0.6 to 10.4 ± 0.6 kg). In Phase 2 there were significant increases in whole-body BMD (from 1.41 ± 0.02 to 1.43 ± 0.02 g/cm2), leg (from 1563 ± 43 to 1572 ± 43 g) and whole-body BMC (from 3807 ± 100 to 3860 ± 100 g), tibial mass (14 % site) (from 3.72 ± 0.08 to 3.74 ± 0.08 g), tibial strength (SSI(POL)14 % site) (from 2331 ± 78 to 2378 ± 78 mm3), and tibial density (4 % site) (from 382 ± 8 to 388 ± 8 mm3). In Phase 3, there was a significant decrease in tibial mass (14 % site) (from 3.74 ± 0.08 to 3.72 ± 0.08 g). Bootstrapped (BCa 95 % CI) Pearson correlations showed that in Phase 2 there were significant positive relationships between the increases in leg BMC and total distance (r = 0.44, 0.01–0.80), accelerations (r = 0.45, 0.08–0.75), and decelerations (r = 0.49, 0.07–0.83), and between the increase in tibial strength (SSI(POL)14 % site) and accelerations (r = 0.53, 0.19–0.80). High magnitude dynamic actions, such as accelerations and decelerations were positively correlated with changes in bone characteristics during a professional football season and should be considered by practitioners when prescribing exercise to induce bone adaptation.

Multi-atlas segmentation and quantification of muscle, bone and subcutaneous adipose tissue in the lower leg using peripheral quantitative computed tomography.

Accurate and reproducible tissue identification is essential for understanding structural and functional changes that may occur naturally with aging, or because of a chronic disease, or in response to intervention therapies. Peripheral quantitative computed tomography (pQCT) is regularly employed for body composition studies, especially for the structural and material properties of the bone. Furthermore, pQCT acquisition requires low radiation dose and the scanner is compact and portable. However, pQCT scans have limited spatial resolution and moderate SNR. pQCT image quality is frequently degraded by involuntary subject movement during image acquisition. These limitations may often compromise the accuracy of tissue quantification, and emphasize the need for automated and robust quantification methods. We propose a tissue identification and quantification methodology that addresses image quality limitations and artifacts, with increased interest in subject movement. We introduce a multi-atlas image segmentation (MAIS) framework for semantic segmentation of hard and soft tissues in pQCT scans at multiple levels of the lower leg. We describe the stages of statistical atlas generation, deformable registration and multi-tissue classifier fusion. We evaluated the performance of our methodology using multiple deformable registration approaches against reference tissue masks. We also evaluated the performance of conventional model-based segmentation against the same reference data to facilitate comparisons. We studied the effect of subject movement on tissue segmentation quality. We also applied the top performing method to a larger out-of-sample dataset and report the quantification results. The results show that multi-atlas image segmentation with diffeomorphic deformation and probabilistic label fusion produces very good quality over all tissues, even for scans with significant quality degradation. The application of our technique to the larger dataset reveals trends of age-related body composition changes that are consistent with the literature. Because of its robustness to subject motion artifacts, our MAIS methodology enables analysis of larger number of scans than conventional state-of-the-art methods. Automated analysis of both soft and hard tissues in pQCT is another contribution of this work.

Oral Contraceptives and Female Rowers' Skeletal Health.

Redinger, AL and Baker, BS. Oral contraceptives and female rowers' skeletal health. J Strength Cond Res 37(3): 669-677, 2023-Previous studies suggest that women using oral contraceptives (OC) experience fewer skeletal benefits from exercise compared with non-OC users. These findings may be especially important for athletes competing in weight-supported sports with a high prevalence of low bone mineral density and fracture, such as rowing. The purpose of this study was to examine skeletal health and bone injuries in collegiate female rowers. Forty-nine National Collegiate Athletic Association Division I female rowers completed general health, menstrual history, and bone physical activity questionnaire (BPAQ) surveys. Dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scans were used to assess bone content, density, and geometry. Contraceptive (OC users n = 14, non-OC users n = 35) and self-reported stress fracture (SFx n = 11, None n = 38) groups were analyzed using analysis of covariance and independent t -tests. Additionally, effect sizes ( d ) were calculated and significance was set at p ≤ 0.05. Oral contraceptive users had reduced lumbar spine areal bone mineral density after adjustment for Total BPAQ ( d = 0.58; p = 0.041) compared with non-OC users, but all other total body and site-specific DXA measures of bone mineral content and density were similar between contraceptive and injury groups. When comparing bone geometry of the 4, 38, and 66% tibiae using pQCT, no significant differences were found after adjustment for either contraceptive or injury group (all p > 0.060). Our findings suggest that OC usage was not associated with reduced skeletal health in competitive female rowers as evidenced by all Z-scores being above -2.0 and similar bone indices of mineralized content, density, geometry, and estimated strength between the groups.

Sex-differences In Bone Density, Geometry, And Estimated Strength Adaptations To 10-weeks Of Military Officer Training

Mechanical loading (e.g. physical activity) is associated with changes in bone density and structure; however, few investigations have examined the adaptive bone response to arduous military training in men and women. PURPOSE Investigate the effects of military training on volumetric bone density (vBMD), geometry, and strength in men and women who complete Marine Corps Officer Candidates School (OCS). METHODS Male and female candidates (n=267) completed a tibial peripheral quantitative computed tomography (pQCT) scan before and after a 10-week physically intensive military training course. Three-dimensional vBMD, geometry, and estimated bone strength were assessed at the 4%, 38%, and 66% sites. Wilcoxon signed-rank tests assessed changes across training. Data are mean±SEM, α=0.05. RESULTS Subjects were aged 19-35 (25.3±0.2 yrs) with a BMI 25.5±0.1 kg/m2. At the distal (4%) tibia, increases in total vBMD (pre: 354.5±2.7, post: 356.3±2.7 mg/cm3), trabecular vBMD (294.3±2.2, 295.6±2.2 mg/cm3), and estimated compression strength (BSI; 154.7±2.2, 156.2±2.1 mg2/mm4) were observed in men (n=222, p<0.001). In women (n=39), total vBMD (324.2±5.1, 326.5±5.2 mg/cm3 p=0.03), trabecular vBMD (262.7±4.8, 264.4±4.9 mg/cm3 p=0.01), and BSI (105.9±3.3, 107.4±3.4 mm3 p<0.01) also increased. At the midshaft (38%) tibia, total vBMD (938.1±3.7, 938.9±3.7 mg/cm3 p=0.03), cortical thickness (6.8±0.1, 6.8±0.1 mm, p<0.01), periosteal circumference (77.0±0.3, 77.1±0.3 mm p<0.01) and estimated bending strength (SSI; 2182.7±25.9, 2193.8±25.1 mm3 p=0.02) increased in men (n=208). In women (n=40), only periosteal circumference increased (70.0±0.6, 70.1±0.6 mm p=0.05). At the proximal (66%) tibia, no significant changes (p>0.05) were observed in men (n=200). In women (n=38), total vBMD decreased (735.9±9.0, 732.7±8.8 mg/cm3 p=0.04) and periosteal circumference increased (82.5±0.9, 82.8±0.9 mm p<0.01) following training. CONCLUSION Bone adaptations in response to 10 weeks of military training are slight (≤1.5%), but statistically significant and may be sufficient to improve estimates of bone strength. Changes are further dependent on biological sex and anatomical location.

GPR109A gene deletion ameliorates gonadectomy-induced bone loss in mice.

Sex steroid deficiency plays critical roles in the pathophysiology of bone as the result of uncertain bone remodeling, i.e., increased bone resorption with equivocal bone formation. We have previously shown that GPR109A, a G protein coupled receptor, controls osteoclastogenesis and bone resorption, where global GPR109A deletion decreased osteoclast bone resorption and increased bone mass. Here, we used global GPR109A gene deletion, ovariectomized (OVX) and orchidectomized (ORX) mouse models to probe the role of GPR109A in gonadectomy-induced bone loss in female and male mice. Six months old GPR109A-/- mice and their wild type littermates were allocated to Sham or gonadectomized groups for six weeks. Using densitometric micro-CT confirmed by peripheral quantitative CT (pQCT) scans on tibia and spine, and three-point bending test on femur ex vivo, we found the bone volume, trabecular number, as well as bone mineral density and content in both trabecular and cortical sites were significantly decreased in wild type OVX and ORX compared with respective Sham groups. While bone mass in both male and female GPR109A-/- Sham groups were significantly higher compared with their respective wild type Sham groups, global GPR109A gene deletion ameliorated gonadectomy-induced bone loss. In GPR109A-/- females, most of bone mass and strength parameters measured by micro-CT, pQCT and three-point bending test were not different between Sham and OVX groups. In wild type but not in GPR109-/- mice, bone remodeling marker measurements indicated that both bone resorption (Cathepsin K) and bone formation (osteocalcin) markers were increased in gonadectomized mice compared to sham, with the exception of bone specific ALP, which was decreased in gonadectomized mice. Expression of bone resorption markers (Cathepsin K) were significantly lower, but β-catenin expression was higher in GPR109A-/- mice compared with their wild type littermates. Collectively, these data indicate that global GPR109A deletion ameliorates gonadectomy-induced bone loss through suppression of bone resorption.

Assessment of Activity Profiles in Older Adults and Lower Limb Bone Parameters: Observations from the Hertfordshire Cohort Study

As muscle strength and function decline with age the optimal high-impact physical activity (PA) required for bone remodelling is rarely achievable in older adults. This study aimed to explore the activity profiles of community-dwelling older men and women and to assess the relationship between individual PA profiles and lower limb bone parameters. Participants from the Hertfordshire Cohort Study wore triaxial accelerometers for 7 days and counts of low (0.5–1.0 g), medium (1.0–1.5 g), and high (> 1.5 g) vertical-impact activity were calculated. Two years later, participants underwent a pQCT scan of the tibia (4% and 38% sites) to obtain measures of bone mineral density and bone geometry. Linear regression was used to quantify associations between bone and PA loading profiles adjusting for age, sex, loading category, and BMI. Results are presented as β [95% confidence interval]. Bone and PA data were available for 82 participants. The mean (SD) age at follow-up was 81.4(2.7) years, 41.5% (n = 34) were women. The median low-impact PA count was 5281 (Inter-quartile range (IQR) 2516–12,977), compared with a median of only 189 (IQR 54–593) in medium, and 39 (IQR 9–105) in high-impact counts. Positive associations between high-impact PA and cortical area (mm2), polar SSI (mm3), and total area (mm2) at the 38% slice (6.21 [0.88, 11.54]; 61.94 [25.73, 98.14]; 10.09 [3.18, 16.99], respectively). No significant associations were found at distal tibia. These data suggest that maintaining high (> 1.5 g)-impact activity is difficult for older adults to achieve; however, even small amounts of high-impact PA are positively associated with selected cortical bone parameters 2 years later.

Tibial Bone Geometry Is Associated With Bone Stress Injury During Military Training in Men and Women.

Bone stress injuries (BSI) are a common musculoskeletal condition among exercising and military populations and present a major burden to military readiness. The purpose of this investigation was to determine whether baseline measures of bone density, geometry, and strength, as assessed via peripheral quantitative computed tomography (pQCT), are predictive of tibial BSI during Marine Officer Candidates School training. Tibial pQCT scans were conducted prior to the start of physical training (n = 504; Male n = 382; Female n = 122) to measure volumetric bone mineral density (vBMD), geometry, robustness, and estimates of bone strength. Bone parameters were assessed at three tibial sites including the distal metaphysis (4% of tibial length measured from the distal endplate), mid-diaphysis (38% of tibial length measured from the distal endplate), and proximal diaphysis (66% of tibial length measured from the distal endplate). Injury surveillance data was collected throughout training. Four percent (n = 21) of the sample were diagnosed with a BSI at any anatomical site during training, 10 injuries were of the tibia. Baseline bone parameters were then tested for associations with the development of a tibial BSI during training and it was determined that cortical bone measures at diaphyseal (38 and 66%) sites were significant predictors of a prospective tibial BSI. At the mid-diaphysis (38% site), in a simple model and after adjusting for sex, age, and body size, total area [Odds Ratio (OR): 0.987, 0.983], endosteal circumference (OR: 0.853, 0.857), periosteal circumference (OR: 0.863, 0.824), and estimated bending strength (SSI; OR: 0.998, 0.997) were significant predictors of a BSI during training, respectively, such that lower values were associated with an increased likelihood of injury. Similarly, at the proximal diaphysis (66% site), total area (OR: 0.989, 0.985), endosteal circumference (OR: 0.855, 0.854), periosteal circumference (OR: 0.867, 0.823), robustness (OR: 0.007, 0.003), and SSI (OR: 0.998, 0.998) were also significant predictors of BSI in the simple and adjusted models, respectively, such that lower values were associated with an increased likelihood of injury. Results from this investigation support that narrower bones, with reduced circumference, lower total area, and lower estimated strength are associated with increased risk for tibial BSI during military training.

Once daily calcium (1000mg) and vitamin D (1000IU) supplementation during military training prevents increases in biochemical markers of bone resorption but does not affect tibial microarchitecture in Army recruits.

Basic combat training (BCT) is a period of novel physical training including load carriage resulting in higher risk of stress fracture compared to any other time during military service. Prior trials reported a 20% reduction in stress fracture incidence with Ca and vitamin D (Ca+D) supplementation (2000mg Ca, 800IU vitamin D), and greater increases in tibia vBMD during BCT compared to placebo. The primary objective of this randomized, double-blind, placebo-controlled trial was to determine the efficacy of a lower dose of Ca (1000mg/d Ca, 1000IU vit D) on PTH, bone biomarkers and tibial microarchitecture during BCT. One hundred volunteers (50 males, 50 females; mean age 21.8±3.5 y) were block randomized by race and sex to receive a daily Ca+D fortified food bar or placebo. Anthropometrics, dietary intake, fasted blood draws and high resolution pQCT scans of the distal and mid-shaft tibia were obtained at the start of BCT and 8 wks later at the conclusion of training. As compliance was 98% in both treatment groups, an intent-to-treat analysis was used. At the distal tibia, total vBMD, Tb.vBMD, Tb.N, Th.Th and Tb.BV/TV increased (+1.07 to 2.12% for all, p<0.05) and Tb.Sp decreased (0.96 to 1.09%, p<0.05) in both treatment groups. At the mid-shaft, Ct.Pm increased (+0.18 to 0.21%, p=0.01) and Ct.vBMD decreased (-0.48 to -0.77%, p<0.001) in both groups. Ca+D prevented increases in CTX and TRAP, which were observed in the placebo group (group-by-time, p<0.05). Mean circulating 25OHD, BAP, P1NP and iCa increased and PTH decreased in both treatment groups (p<0.05). These results, in agreement with other studies, suggest that bone microarchitectural changes indicative of bone formation occur during BCT. While Ca+D supplementation at lower doses than those tested in previous studies prevented increases in biochemical markers of bone resorption in this study, there were no significant changes in bone tissue after 8 wks of Army BCT.

BONE-MUSCLE-FAT INTERACTIONS AND PERFUSIVE EVIDENCE OF INFLAMMATION IN NON-OVERWEIGHT POSTMENOPAUSAL WOMEN WITH EARLY KNEE OA

Postmenopausal women are affected by a decline of estrogen resulting in an established insult on bone (loss), muscle (loss), and fat (gain). These effects are likely not limited to central sites. We were interested in potential damage to the knee in this process and how it contributes to known phenotypes observed in osteoarthritis within this population of women. To glean evidence of inflammation, we investigated perfusion kinetics within periarticular bone, muscle, and fat tissues. To investigate how periarticular muscle and fat relate to subchondral bone properties; and to understand how perfusion may mediate these relationships. This was a cross-sectional study of 52 postmenopausal women recruited by convenience sampling at the University Health Network (Toronto). Women 60-85 years old with evidence of knee pain were included if their BMI upon screening was <=25 kg/m 2 and had no renal disease or contraindications to MRI or Gadolinium for Dynamic Contrast-Enhanced (DCE)-MRI. Time resolution on DCE-MRI scans was 7 ms and Toft's pharmacokinetic model was used to estimate perfusion rate, Kep, within each knee compartment and the infrapatellar fat pad (IPFP) using Tissue4D (Siemens) (Fig 1). Periarticular inter- and intramuscular fat (IMF) was segmented on transaxial proton-density weighted MRI using the iterative threshold-seeking algorithm (ITSA) in Python (Fig 2). Subchondral BMD, periarticular muscle mass, and IPFP content were quantified from compartment-specific pQCT scans at 200 µm in-plane pixel size on Stratec software (Fig 3). Where relevant, compartment-specific associations were obtained using general linear or logistic regression models, adjusting for age and BMI at minimum, with 95% confidence. A lower periarticular (calf side) muscle mass (b= -0.58(-1.02,-0.15)per 1mg) and density (b= -2.76(-5.35,-0.17)per 1mg/cc) was significantly associated with higher medial and lateral (b= -4.57(-7.21,-1.93)per 1mg/cc) subchondral BMD (mg/cc) of the tibia. While the directionality was similar for MR measures of IMF on the calf side, it was only marginally significant. In contrast, a higher IMF volume on the thigh side was associated with lower subchondral BMD of medial femoral (b= -2.39(-4.09,-0.69)) and tibial (b= -1.58(-3.05,-0.11)) compartments. Both higher periarticular IMF(MRI) and lower muscle mass(CT) were correlates of greater perfusion (Kep) of the lateral tibia (b= 1.69 to 2.88 per 1unit, p<0.02). Correspondingly, a higher perfusion of the lateral tibia(b=1.25(0.34,2.15)) was associated with a co-localized higher subchondral BMD. On the other hand, greater perfusion in the IPFP was related to a lower co-localized subchondral BMD (b= -1.70 to -2.22, p<0.01). Although no formal mediation analysis was performed in this smaller pre-pandemic sample, there is evidence to suggest that periarticular muscle and fat may influence subchondral bone by triggering nearby inflammation. The translated effects appear to differ - with correlates on the calf/tibia side resulting in higher BMD, and correlates on the thigh/femur side resulting in lower BMD. It is possible that the observed tibial BMD may reflect the beginning of a collapsing architecture. CIHR PJT156274. Arthritis Society Ken Smith Stars Career Development Award. None of the authors have disclosures. CORRESPONDENCE ADDRESS: andy.wong@uhnresearch.ca

Side-Side Radial Strength Differences In The Cortex In Female Volleyball Players Compared To Controls

INTRODUCTION: Repetitive mechanical loading optimizes bone strength as reported in studies investigating side to side differences in within-subject models using athletes from sports with high repetitive loads and that require use of a dominant lower limb (Weatherholt and Warden, 2016). Similarly, racquet sport players yielded greater strength differences compared to controls in their racquet limb (Kontulainen et al., 2003). Such differences are not yet fully understood in female volleyball players; therefore, due to the highly repetitive striking of a dominant upper limb, the use of female volleyball players is an appropriate population to determine such strength differences. PURPOSE: To determine the percent differences in cortical strength traits between the dominant-non dominant radii in female volleyball players compared to a control group. METHODS: Division II female volleyball players (VB) (N = 16) and age-match controls (CON) (N = 15) underwent peripheral quantitative computed tomography (pQCT) scans to measure bone strength in both radii at the 66% site. Side to Side differences in cortical density (ΔCoD, mg/cm3), cortical area (ΔCoA mm2), strength strain index (ΔSSIp mm3), and moment of inertia (ΔMoI mm4) were assessed using a 2x4 mixed ANOVA. RESULTS: VB (19 yrs + 1.2); CON (22.5 yrs + 3.3). No significant differences between dominant-non dominant radii across all variables were found. Radii cortical strength variables resulted in the following ΔCoD: VB -0.96 % (CI -1.93-0.01); CON -0.45 % (CI -0.03-0.87), ΔCoA: VB 2.12% (CI -0.61-4.85); CON 1.49% (CI -0.21-3.19), ΔSSIp: VB 0.31% (CI -5.8-6.42); CON -2.66 % (CI -7.29-1.97), ΔMoI: VB 4.77 % (CI -1.39-10.93); CON 2.98% (CI -0.46-6.42). CONCLUSION: No significant differences between the dominant-non dominant radii were found in Division II female volleyball players compared to age-matched controls. However, the structural variables CoA and MoI show greater percent differences compared to control than CoD. These data suggest that volleyball may not be an appropriate model for within-subject analysis for bone adaptation due to the type of mechanical loading that is common in the sport. Factors such as start-to-play age, position, and career duration may affect these side to side differences; further investigations are needed on a larger sample size.

Evolution and biomechanical variation in mammalian ungual phalanges with respect to locomotion

Past studies of the morphology of the claw-bearing phalanges among mammalian taxa has revealed a correspondence of ungual phalanx shape and the broad form of locomotor behavior carried out by those taxa. Further research has provided evidence for convergence in the morphology of ungual phalanges among distantly related taxa that engage in similar locomotion. This evolutionary parallelism is proposed to have been motivated by conserved, shared morphogenic pathways. Such evidence would argue that, despite phylogenetic divergence, we would expect to observe: 1) similar biomechanical properties in ungual cross-sectional geometry among unrelated taxa performing similar forms of locomotion; and 2) phylogenetic modeling of the evolution of ungual phalanx morphology should demonstrate evidence for selection and convergence. In this study, we test these hypotheses using linear dimensions and cross-sectional geometric properties (CGSP) obtained from 42 mammalian taxa. This sample represents a breadth of taxa that have previously been classified into five broad locomotor guilds (arboreal, cursorial, fossorial, generalist, scansorial). CSGP (Ix, Iy, J) were obtained using a Stratec pQCT scanner, and linear dimensions of the phalangeal length, mid-length mediolateral width and dorsopalmar height, and extensor and flexor lever arm lengths were taken using digital Mitutoyo sliding calipers. MANOVAs of linear and CSGP traits demonstrate significant differences in locomotor groups (Pillai's Trace = 0.7206; p=0.0007). Discriminant function analysis shows this is motivated by J and the proportion of mediolateral width to dorsopalmar height of the phalangeal mid-length. We then subjected these properties to phylogenetic models assessing evolutionary models of Brownian motion (using R packages ‘bayou’ and ‘OUwie’). Results present little evidence for shared selective regime changes among taxa. One notable model results indicates selective shifts that occurred among taxa that evolved from an ancestral state of mediolaterally narrow phalanges to broader phalanges (as would be associated with fossorial behaviors). Thus, while convergences in shape and CSGP that relate to locomotor behavior are observed among taxa, phylogenetic comparative methods support selection as occurring only in species that evolved from a narrow to broader ungual phalanx morphology. Further analyses using OU models were used to assess phylogenetic models of convergence.

Evaluation of Femoral Bone Fracture Healing in Rats by the Modal Damping Factor and Its Correlation With Peripheral Quantitative Computed Tomography.

IntroductionMonitoring the progress of fracture healing is essential in order to establish the appropriate timing that ensures adequate bone strength for weight-bearing. In the present experimental study on a rat model of femoral fracture healing, the measurement of bone density and strength by peripheral quantitative computerized tomography (pQCT) was correlated with the modal damping factor (MDF) method.MethodsFour groups of 12 male six-month-old Wistar rats each were anesthetized and submitted to baseline femoral pQCT and MDF scanning, followed by aseptic midshaft osteotomy of the right femur which was fixed by a locking intramedullary nail technique. The animals were left to recover and re-scanned following euthanasia of each group after six, eight, 10, and 12 weeks, respectively. The parameters measured by the pQCT method were total bone mineral density (BMD) and polar strength strain index (SSIp).ResultsFracture healing progressed over time and at 12 weeks post-osteotomy there was no statistically significant difference between the osteotomized right and the control left femurs regarding MDF, BMD, and SSIp measurements. The highest correlations for the osteotomized femurs were observed between MDF and BMD (r = -0.647, P = 0.043), and between MDF and SSIp (r = -0.350, P = 0.321), at 10 weeks postoperatively. The high to moderate correlations between MDF and BMD, and between MDF and SSIp respectively, support the validity of MDF in assessing fracture healing.ConclusionsBased on our findings in this fracture healing animal model, the results from the MDF method are reliable and correlate highly with the total BMD and moderately with the SSI polar values obtained by the pQCT method of bone quality measurement. Further studies are needed which may additionally support that the MDF method can be an attractive portable alternative to monitor fracture healing in the community.

Pregnancy-Related Change in pQCT and Bone Biochemistry in a Population With a Habitually Low Calcium Intake.

In pregnancy, changes in maternal calcium (Ca) economy occur to satisfy fetal Ca demand. It is unclear whether maternal mineral reserves facilitate these requirements and no data exist from sub-Saharan Africa. The aim was to determine skeletal changes with peripheral quantitative computed tomography (pQCT) and bone biochemistry between early second and third trimesters. Pregnant rural Gambians aged 18 to 45 years (n=467) participating in a trial of antenatal nutritional supplements (ISRCTN49285450) had pQCT scans and blood collections at mean (SD) 14 (3) and 31 (1) weeks' gestation. Outcomes were pQCT: radius/tibia 4% total volumetric bone mineral density (vBMD), trabecular vBMD, total cross-sectional area (CSA), 33%/38% radius/tibia cortical vBMD, bone mineral content (BMC), total CSA; biochemistry: collagen type 1 cross-linked β-C-telopeptide (β-CTX), type 1 procollagen N-terminal (P1NP), parathyroid hormone (PTH), and 1,25(OH)2 D. Independent t tests tested whether pooled or within-group changes differed from 0. Multiple regression was performed adjusting for age. Data for change are expressed as mean (confidence interval [CI] 2.5, 97.5%). Radius trabecular vBMD, cortical vBMD, and BMC increased by 1.15 (0.55, 1.75)%, 0.41 (0.24, 0.58)%, and 0.47 (0.25, 0.69)%. Tibia total and trabecular vBMD increased by 0.34 (0.15, 0.54)% and 0.46 (0.17, 0.74)%, while tibia cortical vBMD, BMC, and cortical CSA increased by 0.35 (0.26, 0.44)%, 0.55 (0.41, 0.68)% and 0.20 (0.09, 0.31)%, respectively. CTX, PTH, and 1,25(OH)2 D increased by 23.0 (15.09, 29.29)%, 13.2 (8.44, 19.34)%, and 21.0 (17.67, 24.29)%, while P1NP decreased by 32.4 (-37.19, -28.17)%. No evidence of mobilization was observed in the peripheral skeleton. Resorption, although higher in late versus early gestation, was lower throughout pregnancy compared with non-pregnant non-lactating (NPNL) in the same community. Formation was lower in late pregnancy than in early, and below NPNL levels. This suggests a shift in the ratio of resorption to formation. Despite some evidence of change in bone metabolism, in this population, with habitually low Ca intakes, the peripheral skeleton was not mobilized as a Ca source for the fetus. © 2021 crown copyright . Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). The article published with the permission of the Controller of HMSO and the Queen's Printer of Scotland..

The Assessment of Skeletal Muscle and Cortical Bone by Second-generation HR-pQCT at the Tibial Midshaft

Background: Peripheral quantitative computed tomography (pQCT) is the current densitometric gold-standard for assessing skeletal muscle at the 66% proximal tibia site. High resolution peripheral quantitative computed tomography (HR-pQCT) is a leading technology for quantifying bone microarchitecture at the distal extremities, and with the second-generation HR-pQCT it is possible to measure proximal limb sites. Therefore, the objectives of this study were to: (1) assess the feasibility of using HR-pQCT to assess skeletal muscle parameters at the 66% proximal tibia site, and (2) test HR-pQCT skeletal muscle measurement reproducibility at this site. Methods: Adult participants (9 males; 7 females; ages 31–75) received 1 pQCT scan and 2 HR-pQCT scans at the 66% proximal site of the nondominant tibia. Participants were repositioned between HR-pQCT scans to test reproducibility. HR-pQCT and pQCT scans were analyzed to quantify muscle cross-sectional area (CSA) and muscle density. Coefficients of determination and Bland-Altman plots compared muscle parameters between pQCT and HR-pQCT. For short-term reproducibility, root-mean-square of coefficient of variance and least significant change were calculated. Results: HR-pQCT and pQCT measured muscle density and muscle CSA were positively correlated (R2 = 0.66, R2 = 0.95, p < 0.001, respectively). Muscle density was equivalent between HR-pQCT and pQCT; however, there was systematic and directional bias for muscle CSA, such that muscle CSA was 11% lower with HR-pQCT and bias increased with larger muscle CSA. Root-mean-square of coefficient of variance was 0.67% and 0.92% for HR-pQCT measured muscle density and muscle CSA, respectively, while least significant change was 1.4 mg/cm3 and 174.0 mm2 for muscle density and muscle CSA, respectively. Conclusion: HR-pQCT is capable of assessing skeletal muscle at the 66% site of the tibia with good precision. Measures of muscle density are comparable between HR-pQCT and pQCT.

Sex-Specific Associations Between Cardiac Workload, Peripheral Vascular Calcification, and Bone Mineral Density: The Gambian Bone and Muscle Aging Study.

Noncommunicable diseases (NCD) are rapidly rising in Africa, with multimorbidity increasing the burden on health and social care. Osteoporosis and cardiovascular disease (CVD) share common risk factors; both often remain undiagnosed until a major life-threatening event occurs. We investigated the associations between cardiac workload, peripheral vascular calcification (PVC), and bone parameters in Gambian adults. The Gambian Bone and Muscle Aging Study (GamBAS) recruited 249 women and 239 men aged 40 to 75+ years. Body composition and areal bone mineral density (aBMD) were measured using dual-energy X-ray absorptiometry; peripheral quantitative computed tomography (pQCT) scans were performed at the radius and tibia. Supine blood pressure and heart rate were measured and used to calculate rate pressure product and pulse pressure. Presence of PVC was determined from tibia pQCT scans. Sex interactions were tested (denoted as p-int); adjustments were made for residuals of appendicular lean mass (ALM) and fat mass (FM). There were negative associations between rate pressure product and aBMD in women only, all p-int < .05; after adjustment for ALM residuals, for every 10% increase in rate pressure product, aBMD was lower at the whole body (-0.6% [-1.2, -0.1]), femoral neck (-0.9% [-1.8, -0.05]), L1 to L4 (-0.6% [-1.7, 0.5]), and radius (-1.9% [-2.8, -0.9]); there were similar associations when adjusted for FM residuals. Similar negative associations were found between pulse pressure and aBMD in women only. PVC were found in 26.6% men and 22.5% women; women but not men with calcification had poorer cardiac health and negative associations with aBMD (all sites p-int < .001). There were consistent associations with cardiac parameters and pQCT outcomes at the radius and tibia in women only. Multiple markers of cardiac health are associated with poorer bone health in Gambian women. In the context of epidemiological transition and changing NCD burden, there is a need to identify preventative strategies to slow/prevent the rising burden in CVD and osteoporosis in Sub-Saharan Africa. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Studying bone mineral density in young people: The complexity of choosing a pQCT reference database.

Many chronic illnesses affect bone health, and commonly lead to mineralization abnormalities in young people. As cortical and trabecular bone may be differentially affected in certain diseases, an imaging technique that allows for detailed study of the bone structure is required. Peripheral quantitative computed tomography (pQCT) overcomes the limitations of dual energy X-ray absorptiometry (DXA) and is perhaps more widely available for use in research than bone biopsy. However, in contrast to DXA, where there are large reference datasets, this is not the case for pQCT. Fifty-five children and young adults aged 7 to 30years had the non-dominant tibia scanned at the 3% & 4% sites for trabecular bone mineral density and the 38% site for cortical bone mineral density and bone mineral content. Image acquisition and analysis was undertaken according to the protocols of two of the largest reference datasets for tibial pQCT. The Z-scores generated were compared to examine the differences between protocols and the differences from the expected median of zero in a healthy population. The trabecular bone mineral density Z-scores generated by the two protocols were similar. The same was true for cortical mineral content Z-scores at the 38% site. Cortical bone mineral density was significantly different between protocols and likely affected by differences in the ethnicity of our cohort compared to the reference datasets. Only one reference dataset extended from childhood to young adulthood. Only trabecular bone mineral density, periosteal and endosteal circumference Z-scores from one methodology were not significantly biased when tested for deviation of the median from zero. pQCT is a useful tool for studying trabecular and cortical compartments separately but, there are variations in pQCT scanning protocols, analysis methodology, and a paucity of reference data. Reference datasets may not be generalizable to local study populations, even when analysed using identical analysis protocols.

Peripheral quantitative computed tomography (pQCT) in 12- and 24-month-old children - Practical aspects and descriptive data.

Peripheral quantitative computed tomography (pQCT) is a useful tool to assess detailed bone characteristics. Its utility in infants is however limited due to lack of reference data and technical challenges. The purpose of this study was to provide data on length- and weight-adjusted pQCT values and to present a quality grading system for healthy children aged 12 and 24months. As a part of the Vitamin D intervention in Infants (VIDI) trial, we collected pQCT and anthropometric data from 855 children at 12months and from 784 children at 24months. Bone mineral content (BMC; mg/mm), volumetric bone mineral density (vBMD; mg/cm3), cross-sectional area (CSA; mm2), polar-moment of inertia (PMI; mm4), and periosteal circumference (PsC; mm) were assessed for total bone at 20% distal site of the left tibia using pQCT (Stratec XCT2000L). We evaluated the impact of scan quality on bone measures. Total bone parameters were assessed for boys and girls separately. The means of the bone parameters were also compared in relation to age. The associations between bone parameters and weight, length, sex and scan quality were analyzed. We included scans with sufficient quality (Grade 1-5) in the final analyses: 679/855 (79%) at 12months and 709/784 (90%) at 24months. Altogether 39% of the scans at 12months and 51% at 24months were of good or excellent quality (Grade 1-2). Scan quality had an impact on BMCs at 12 and 24months (p=0.001 and p=0.017, respectively) but not on other bone parameters. Boys presented greater total bone BMC, CSA, PMI and PsC values at 12 and 24months but vBMDs were similar. All bone parameters showed a significant increase between 12 and 24months for both sexes. When adjusting bone parameters for weight, length and scan quality, differences between sexes disappeared. Weight was the strongest modifier of BMC, CSA, PMI and PsS at 12 and 24months. This study increases our understanding on bone parameters in young children and demonstrates the suitability of pQCT in bone research in infants. The described pQCT data and scan quality grading system should prove useful in evaluating data reliability in research settings. NCT1723852.