Strength Strain Index Research Articles

Micronutrient Status During Military Training and Associations With Musculoskeletal Health, Injury, and Readiness Outcomes.

Micronutrient status, specifically vitamin D and iron, represent modifiable factors for optimizing military readiness. The primary purpose of this investigation was to determine associations between micronutrient deficiency (i.e.,iron status and 25-hydroxy-vitamin D [25(OH)D]) and operationally relevant outcomes (i.e.,skeletal health, musculoskeletal injury) at baseline and post-10weeks of arduous military training. A total of 227 (177 men, 50 women) Marine Officer Candidates School (OCS) candidates who completed OCS training with complete data sets were included in this analysis. Vitamin D and iron status indicators were collected at two timepoints, pre (baseline) and post OCS. Musculoskeletal outcomes at the mid- and proximal tibial diaphysis were assessed via peripheral quantitative computed tomography. Micronutrient status declined following OCS training in men and women and was associated with musculoskeletal outcomes including greater bone strength (strength strain index) at the mid-diaphysis site in those with optimal status (M = 38.26mm3, SE = 15.59) versus those without (M = -8.03mm3, SE = 17.27). In women (p = .037), endosteal circumference was greater in the deficient group (M = 53.26mm, SE = 1.19) compared with the optimal group (M = 49.47mm, SE = 1.31) at the proximal diaphysis. In men, greater baseline hepcidin concentrations were associated with an increased likelihood of suffering musculoskeletal injury during training. Vitamin D and iron status declined over the course of training, suggesting impaired micronutrient status. Differences in musculoskeletal outcomes by micronutrient group suggests optimal vitamin D and ferritin concentrations may exert beneficial effects on bone fatigability and fracture reduction during military training.

Cortical impairment and reduced muscle mass in children and young adults with nephropathic cystinosis.

Nephropathic cystinosis is an orphan autosomal recessive lysosomal storage disease characterized by a deficiency of cystinosin, a cystine transporter protein, leading to tissue damage, primarily in the kidney and cornea. With the introduction of cystine-depleting therapy with cysteamine and the possibility to survive to adulthood, new challenges of skeletal complications are a concern, with sparse data available regarding bone development. The aim of the current study was to gain more information on bone density and geometry in these patients. Fifty-one patients (29 males, 22 females) with genetically proven nephropathic cystinosis were clinically evaluated with a medical history, physical examination, grip strength measurements, and biochemical and imaging studies. Bone mineral density, bone geometry, and muscle cross sectional area were measured, and muscle was evaluated. Results were compared with age- and gender-specific reference data. Z-scores for height (mean [M] = -1.75, standard deviation [SD] = 1.43), weight (M = -1.67, SD = 1.29), and BMI (M = -0.98, SD = 1.29) were lower than reference data. Medullary cross-sectional area (CSA) and cortical density z-scores were not compromised (M = 0.12, SD = 1.56 and M = -0.25, SD = 1.63, respectively), but cortical CSA z-scores and Strength-Strain Index (SSI) were reduced (M = -2.16, SD = 1.08, M = -2.07, SD = 1.08). Muscular deficits were reflected by reduced z-scores for muscle CSA (M = -2.43, SD = 1.27) and grip strength (M = -3.01, SD = 1.10), along with jump force (34% lower than reference value). Multiple regression analyses indicated an association of muscle mass with medullary CSA and SSI, but not with cortical CSA. While bone density parameters were normal, bone geometry was altered, resulting in a thinner cortex with possible impact on bone strength. Muscle weakness be partially responsible for altered bone geometry and could provide a potential treatment target.

High muscular fitness level may positively affect bone strength and body composition in children with overweight and obesity

SummaryMuscular fitness plays a major role in bone health and body composition in overweight and obese children. It is key that the development of this muscle fitness is affected by absolute isometric strength and dynamic strength.PurposeTo compare bone health and body composition between overweight/obese children considering muscular fitness (MF) levels, and to investigate whether weight-bearing dynamic or absolute isometric strength, both involved in the development of this muscular fitness, are more related with bone health.MethodsMF of 59 overweight or obese children (10.1 ± 0.9 years, 27 females) was measured by a countermovement jump (CMJ), handgrip, and maximal isometric strength of knee extension. Participants were divided into four groups depending on their MF level performing a cluster analysis: 16 children with high MF (HMF) in all tests, 18 with high performance in isometric strength (HIS), 15 with high performance in CMJ (HCMJ) and 10 low isometric and low dynamic force values (LMF). Body composition values were measured by dual energy X-ray absorptiometry, and bone strength values were assessed by peripheral quantitative computed tomography. Motor skills were evaluated using TGMD-3. Multivariate analysis of covariance test was applied to analyse bone strength differences between children in the different MF groups, using maturity offset, height and weight as covariates, and correlations were investigated.ResultsHMF excelled in bone health. HIS had higher cortical bone area, periosteal circumference, bone mass, polar strength strain index and fracture load than LMF, while HCMJ only showed better results in trabecular bone area than LMF. HMF had significantly better values of fracture load and periosteal and endosteal circumferences than HCMJ, but not than HIS.ConclusionsHigh MF level shows positive effects on bone health in overweight/obese children. Those with highest isometric strength had better bone health compared to those with higher dynamic strength.Trial registrationThe research project was registered in a public database Clinicaltrials.gov in June 2020 with the identification number NCT04418713.

Variability of the proximal phalanx in warmblood and coldblood horses – morphological and structural analyses

Anatomical shape as well as bone geometry are important factors for the mechanical properties of stiffness and strength in bones. In the light of this statement, the primary aim of the study was to evaluate the variable forms of the proximal phalanx in different types of horses. Multivariate analyses of data from 81 horses revealed that the proximal phalanx has diverse spatial forms. Differences were observed particularly in the length of the bone and the breadth of its diaphysis. In horses with lighter morphotype, the phalanx is significantly narrower in its middle section. In the second stage of the study, geometrical parameters of the phalanx were analysed with the use of peripheral quantitative computed tomography (pQCT). Tomographic analysis was conducted at three levels: at 15%, 50% and 85% of the bone length. Based on the analysis, we concluded that most of the geometric parameters have higher values in coldbloods but only at the mid-diaphysis (50%) and at 85% of the bone length. Moreover, in coldblood horses, higher strength of the phalanx at these levels, expressed by Strength Strain Index, was observed. We did not observe any significant differences between warmblood and coldblood horses in the metaphyseal proximal region which is located at 15 % of the bone length.

Lower bone strength in young patients with Fontan circulation compared to controls.

Previous reports indicate bone deficits in patients with Fontan circulation. However, the consequences of these deficits on bone strength and when these changes occur are unclear. To compare the tibial bone strength-strain index between young patients (6-19 years) with Fontan circulation and age- and sex-matched controls, and to determine strength-strain-index in subgroups of children (6-12 years) and adolescents (13-19 years) versus controls. The tibia was examined with peripheral quantitative CT. Based on the assessed data, bone strength-strain index was calculated in the lateral and anterior-posterior directions. Twenty patients with Fontan and twenty controls (mean age 13.0 ± 4.4 years; 50% females) were examined. Patients had a lower strength-strain index in the lateral direction compared to controls (808.4 ± 416.8mm3 versus 1162.5 ± 552.1mm3, p = 0.043). Subgroup analyses showed no differences regarding strength-strain index in children (6-12 years) with Fontan circulation compared to controls. However, the adolescents (13-19 years) with Fontan circulation had lower strength-strain indexes in both the lateral and anterior-posterior directions compared to controls (1041.4 ± 299.8mm3 versus 1596.4 ± 239.6mm3, p < 0.001, and 771.7 ± 192.4mm3 versus 1084.9 ± 215.0mm3, p = 0.004). When adjusted for height, there were differences between patients (6-19 years) and controls in strength-strain indexes in both the lateral and anterior-posterior directions. In subgroup analyses, the results remained robust. Young patients (6-19 years) with Fontan circulation have a lower strength-strain index in the tibia compared to controls. Subgroup analyses show that this deficit is mainly driven by the differences in adolescents (13-19 years), which might suggest that bone strength decreases with age.

The Impact of Whole Egg Consumption on Bone Accrual in Healthy Children: A Randomized Controlled Trial.

Dietary interventions designed to examine the role of nutrition on childhood bone accrual have often focused on the role of individual micronutrients (eg, calcium, vitamin D, and zinc) and macronutrients (eg, protein). The osteogenic benefits of whole foods, such as eggs, are not well understood despite eggs being a source of high-quality nutrients and bioactive compounds known to positively influence bone. A significant positive cross-sectional association between whole egg consumption and tibia cortical bone mass has recently been shown in young children; however, randomized controlled trials (RCTs) have not been conducted. This study is a double-blind RCT in male and female children ages 9-13 years of different ancestries, designed to determine if consuming food products with whole eggs (equivalent to 8-10 eggs/wk) versus foods with milk or gelatin (placebo) over a 9-month period will improve measures of bone strength. Total body less head (TBLH) and lumbar spine bone mineral content (BMC) and areal bone mineral density (aBMD) were assessed using dual-energy X-ray absorptiometry (DXA). DXA Z-scores were computed using published pediatric growth charts and were adjusted for height-for-age Z-score (HAZ). Mid-tibia cortical volumetric BMD, BMC, cortical area, total bone area, cortical thickness, and strength strain index were measured using peripheral quantitative computed tomography. Overall, there were no significant intervention effects for any bone outcomes. The increase in spine BMCHAZ Z-score in the egg group versus the gelatin group approached significance (p = 0.07). Significant time effects in TBLH aBMDHAZ Z-score occurred as all groups decreased over 9 months (p < 0.03). Most tibia cortical bone outcomes increased over time (all p < 0.02), but changes did not differ across intervention groups. Whole eggs provide important nutritional benefits for children, but the bone responses to consumption of 8-10 eggs/wk over a period of 9 months in children entering the early stages of puberty were small. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Normal bone density but altered geometry in girls with Turner syndrome.

Data on bone density and stability in Turner syndrome (TS) are contradictory. A confounding factor for interpretation is short stature. The aim was to measure bone density, geometry and stability in girls with TS compared to idiopathic short stature (ISS). From 1999 to 2008, 59 girls with TS (35 prepubertal) were evaluated by pQCT. Mean age was 8.9 in prepubertal and 17.3 years in adolescent girls. Mean height was -3.1 and -1.8 SDS in prepubertal treatment-free and in adolescent, formerly rhGH-treated girls. For comparison, 18 prepubertal ISS girls were studied (age 7.7 years; height -3.3 SDS). Examination of radius with pQCT (XCT 2000). Cortical (CD) and trabecular density (TD), total bone area (TBA), cortical area (CA), cortical thickness, muscle area and strength strain index (SSI) were determined and compared with height related references. In prepubertal girls with TS, TD and CD were normal (0.55 and 0.90 SDS) and comparable to ISS (0.95 and 1.53 SDS). TBA was greater in girls with TS than in ISS (0.87 vs. -0.33 SDS) whereas CA was similar (1.48 vs. 1.43 SDS). The SSI was comparable (1.61 vs. 1.56 SDS). Adolescent girls with TS showed similar results with a TD of 0.48 SDS, a CD of -0.32, TBA of 1.99, a CA of -0.05 and an SSI of 0.88 SDS. The observations are consistent with normal bone density and stability but altered bone geometry in prepubertal and substituted adolescent girls with TS. This peculiarity may reflect SHOX deficiency. We therefore think that timely and adequate estrogen substitution could prevent bone loss in TS.

Comparison of the strength parameters of the bilateral third metacarpal bones in horses by pQCT

The third metacarpal (MC3) bone, along with the proximal phalanx, is one of the bones that are most prone to injury in sport horses. To date, no detailed analysis has been conducted that would compare the strength parameters of bilateral MC3 bones taking into account differences depending on the site of measurement. The aim of the study was to compare strength parameters between the left and right MC3 bones in horses at 10%, 20%, 30%, 40%, 50%, 60%, 70% and 80% of the bone length using peripheral quantitative computed tomography (pQCT). The research material comprised isolated bilateral MC3 bones from 21 horses (age range: 3-27 years). The structure of these bones was measured using high-resolution pQCT. The following bone parameters were determined: polar strength strain index, strength strain index X and strength strain index Y. The computed tomographic analysis of the MC3 bones was carried out at sections from 10% to 80% (every 10%) of the bone length. The statistical analysis showed that in most cases the strength parameters calculated using pQCT were significantly higher for the right MC3 bones at 10%, 20% and 50% of the bone length, i.e. at the proximal metaphysis and at the proximal diaphysis. However, strength parameters measured at 60% and 80% of the diaphyseal length, i.e. at the distal diaphysis, were significantly higher for the left MC3 bones. Further studies of the MC3 bones parameters should focus on the vicinity of the proximal metaphysis and at the proximal diaphysis.

Oral administration of melatonin increases plasma calcium and magnesium and improves bone metabolism in aged male mice

We previously reported that the oral administration of melatonin from 4 to 20 months to male mice improved femoral bone strength and bone density during the aging. Additionally, melatonin receptor, MT2, was immunologically detected in both osteoblasts and osteoclasts of the mouse femoral bone. Thus, melatonin can act on both osteoblasts and osteoclasts to maintain bone strength during the aging process. Here, we analyzed plasma calcium (Ca2+), magnesium (Mg2+), and inorganic phosphorus ([PO4]3-) in 20-month-old male mice with or without administration melatonin (15-20 mg/kg/day) in drinking water. We found that plasma Ca2+ and Mg2+ levels in melatonin-treated mice increased significantly as compared with control mice. In [PO4]3-, melatonin administration tended to increase its plasma level, but did not reach statistical significance. The potential association between these divalent ions and metabolism markers of femoral bone was also examined. In the femoral diaphysis, the plasma Ca2+ and Mg2+ concentrations were positively correlated with periosteal and endosteal circumference which were significantly associated with the Strength Strain Index. Therefore, melatonin treatment enlarged femoral diaphysis and enhanced bone strength by increasing mineral depositions. In addition, the plasma melatonin levels were significantly positive correlation with total bone density and critical thickness in the femoral diaphysis. Since we had not observed the primary trabecular bone and osteoclasts in 20-month-old mice previously, it is suggested that plasma Ca2+ and Mg2+ are not elevated due to bone resorption. The increased plasma Ca2+ and Mg2+ by melatonin may originate from the intestinal absorption of these ions since melatonin binds to the vitamin D3 receptor, its activation is known to promote the intestinal absorption of Ca2+.

Tibial cortical and trabecular variables together can pinpoint the timing of impact loading relative to menarche in premenopausal females.

Though relationships between limb bone structure and mechanical loading have provided fantastic opportunities for understanding the lives of prehistoric adults, the lives of children remain poorly understood. Our aim was to determine whether or not adult tibial skeletal variables retain information about childhood/adolescent loading, through assessing relationships between cortical and trabecular bone variables and the timing of impact loading relative to menarche in premenopausal adult females. Peripheral quantitative computed tomography was used to quantify geometric and densitometric variables from the proximal tibial diaphysis (66% location) and distal epiphysis (4% location) among 81 nulliparous young adult female controls and athletes aged 19-33 years grouped according to intensity of impact loading both pre- and post-menarche: (1) Low:Low (Controls); (2) High:Low; (3) High:High; (4) Moderate:Moderate; (5) Low:Moderate. ANCOVA was used to compare properties among the groups adjusted for age, stature, and body mass. Significant increases in diaphyseal total cross-sectional area and strength-strain index were documented among groups with any pre-menarcheal impact loading relative to groups with none, regardless of post-menarcheal loading history (p < .01). In contrast, significantly elevated distal trabecular volumetric bone mineral density was only documented among groups with recent post-menarcheal loading relative to groups with none, regardless of pre-menarcheal impact loading history (p < .01). The consideration of diaphyseal cortical bone geometric and epiphyseal trabecular bone densitometric variables together within the tibia can identify variation in pre-menarcheal and post-menarcheal impact loading histories among premenopausal adult females.

Reduced bone strength in adults with moderate or complex congenital heart disease

BackgroundWe aimed to study bone mineral density (BMD) and skeletal strength in the growing population of adults with moderate or complex congenital heart disease (CHD). MethodsPeripheral quantitative computed tomography (pQCT) was performed on the radius and tibia in 49 adults with moderate or complex CHD, and in 49 age and sex matched controls (n ​= ​23 [47%] female, mean age 36 ​± ​15.5 years.) Strength in the radius and tibia were presented, respectively, in terms of Strength-Strain Index (SSI). ResultsPatients had similar total BMD as controls in both the radius (807 ​± ​82 vs. 792 ​± ​75 ​mg/cm3, p ​= ​0.3) and tibia (663 ​± ​86 vs. 689 ​± ​67 ​mg/cm3, p ​= ​0.1). In the radius, patients had a lower xSSI than controls (154 ​± ​46 vs. 175 ​± ​54 ​mm3, p ​= ​0.04) but a similar ySSI (178 ​± ​58 vs. 195 ​± ​55 ​mm3, p ​= ​0.1). In the tibia, patients had a lower xSSI (1492 ​± ​399 vs. 1780 ​± ​372 ​mm3, p ​< ​0.001) as well as ySSI (1066 ​± ​304 vs. 1250 ​± ​281, p ​= ​0.002). In a multiple linear regression model, only height was independently associated with decreased skeletal strength in patients tibia in terms of xSSI [F(2,46) ​= ​40.002, p ​< ​0.001, R2 ​= ​0.635]. ConclusionAdults with moderate or complex CHD had reduced strength in the radius and tibia, despite a normal BMD as assessed with pQCT. Their reduced bone strength could increase the risk of future fractures.

Site-Specific Bone Differences and Energy Status in Male Competitive Runners and Road Cyclists

The interaction between mechanical loading and energy availability on bone health in male endurance athletes merits further investigation. The purpose of this study was to compare bone status in male competitive runners and road cyclists and to investigate the influence of energy availability (EA) on bone mineral density (BMD). 18 competitive runners and 19 road cyclists (20-50 years) participated in this study. Areal BMD and body composition were assessed by dual energy x-ray absorptiometry. Volumetric bone variables at the 4% and 66% tibia sites were assessed by peripheral quantitative computed tomography. Energy availability (EA, 7-day dietary and exercise logs) and resting metabolic rate (RMR, open circuit spirometry) were measured as indicators of energy status. Bone loading history, calcium intake, and training history were assessed by questionnaires. After adjusting for age, runners had significantly greater (p < 0.05) areal BMD (femoral neck, left total hip), Z-scores (total body, hips sites), total bone mineral content and trabecular variables (bone mineral content, volumetric BMD, bone strength index) at tibia 4% site, and total volumetric BMD at tibia 66% site than the cyclists (p ≤ 0.05). At the tibia 66% site, cyclists had significantly greater (p < 0.05) total area, periosteal circumference, endosteal circumference, and strength-strain index than runners. Energy variables were similar for runners and cyclists; however, RMR and RMR ratio (measured RMR/predicted RMR) were significantly lower in cyclists (p < 0.001). In conclusion, there were site-specific differences in hip and tibia bone characteristics between runners and cyclists. RMR was associated with several bone outcomes; however, EA was not related to bone health in runners or to dual energy x-ray absorptiometry bone variables in cyclists.

Soccer participation is associated with benefits in tibial bone cross-sectional geometry and strength in young women.

Soccer has been hypothesized to be an ideal sport to stimulate favorable changes in bone properties due the high-intensity, multidirectional movements performed during play. The purpose of this study was to determine if participation in soccer is associated with enhanced bone properties such as volumetric bone mineral density (vBMD), cross-sectional geometry, and estimated strength in the tibias of young, healthy women. Twenty female soccer players (20±1 years) and twenty mass- and height-matched healthy women (21±1 years) participated in this cross-sectional study. Peripheral quantitative computed tomography (XCT 3000; Stratec Medizintechnik, Pforzheim, Germany) was used to assess bone characteristics, including vBMD, cross-sectional moments of inertia (CSMI), and strength/strain index (SSI) at 14%, 38%, and 66% of the tibial length proximal to the distal end plate. One-way multivariate analysis of variances were run to determine the influence of soccer training history on tibial properties. Compared to healthy controls, soccer players had approximately 1.5-3% lower cortical vBMD but 18.5-30% greater CSMI and 16.5-19% greater SSI at the three cross-sectional sites along the tibial diaphysis (all P<0.05). These results suggest that soccer participation is associated with favorable bone cross-sectional geometry and estimates of bone strength. However, randomized controlled intervention trials are needed to confirm whether soccer participation results in favorable bone adaptations in young, healthy adults.

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.

Peak vertical jump power predicts radial bone strength better than hand grip strength in healthy individuals.

Osteoporosis is considered a pediatric disease with geriatric consequences. However, measuring bone strength in children is complex and creates a practical problem for health professionals, teachers and parents. A non-invasive measure of muscle fitness that correlates to bone strength may provide a means to monitor bone strength throughout the lifespan. Therefore, the purpose of this study was to investigate the relationship between common muscle function tests (relative grip strength (RGS), peak vertical jump power (PP)) and bone strength in the radial diaphysis and epiphysis of a healthy population. Healthy participants (n=147 (81 female)) performed a bilateral grip strength test using a hand dynamometer, and a maximal vertical jump test. Peak vertical jump power was calculated from maximal jump height using the Sayer’s equation. Moment of inertia (MoI), cortical area (CoA), cortical bone mineral density (cBMD), and polar strength-strain index (SSIp) were measured using peripheral Quantitative Computed Tomography (pQCT) to determine bone strength parameters at the 66% radial site (predominantly cortical bone). At the 4% site (trabecular bone site), bone mineral content (vBMC.tb), bone mineral density (vBMD.tb), total area (ToA.tb) and bone strength index (BSIc) were measured. Hierarchical multiple regression analyses determined the relationship of each muscle function test for each bone envelope (cortical and trabecular). For the cortical bone measurements: RGS, and PP were both significantly correlated with CoA, MoI, and SSIp. Peak vertical jump power predicted bone strength parameters to a greater extent compared to RGS. For the trabecular bone envelope, RGS was not a predictor of bone strength however peak power was a significant predictor of bone strength parameters. Peak vertical jump power was a significant predictor of bone strength at both trabecular and cortical radial sites. Interestingly PP, a lower limb measurement explained the most variance in the bone strength of the upper limb.

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.

Altered cortical bone strength and lean mass in young women with long-duration (19\xa0years) type 1 diabetes

To investigate bone health and body composition in young women with long-duration type 1 diabetes (T1D) in relation to matched controls. Twenty-three Swedish women, age 19.2–27.9 years, with a T1D duration of 10 years or more were recruited from the Swedish National Diabetes Registry (NDR). An age-, gender- and geography-matched control group was recruited. Bone mass and body composition were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Data was retrieved from the NDR and SWEDIABKIDS registries. T1D individuals had a mean diabetes duration of 19 years. T1D individuals had reduced lean mass (40.0 ± 6.1 kg vs. 43.9 ± 4.9 kg) and were shorter (1.66 ± 0.06 m vs. 1.71 ± 0.06 m) although comparable BMI. Subjects with T1D had lower muscle area (P = 0.0045). No differences were observed for fractures; physical activity; total, lumbar spine or femur areal bone mineral density. The cortical bone strength strain index was lower for TD1 patients (1875 ± 399 mm3 vs. 2277 ± 332 mm3). In conclusion, young women with long-term diabetes duration showed reduced cortical bone strength, decreased periosteal circumference, endosteal circumference and altered body composition. These factors contribute to the health burden of TD1, which warrants further attention for advancing bone health in women with T1D.

Stable bone density in adolescents with severe growth hormone deficiency after six months off rhGH.

Severe growth hormone deficiency causes lean body mass loss in male adolescents and increased fat mass in both sexes. The changes appear after a 6month GH pause. The aim was to examine bone density and structure changes in adolescents with severe GHD during a 6-month rhGH treatment interruption. In total, 113 adolescents (20 females) paused rhGH treatment for 6months at near-final height, and they were retested with arginine-GHRH challenge and basal IGF-1. Severe GHD was diagnosed in 19 individuals (5 females, GH peak <16ng/ml and IGF-1<-1.9 SDS) and excluded in 94 (15 females). Bone density and structure were measured by pQCT of the forearm and DXA of the total body at cessation of rhGH and 6months later. In severe adolescent GHD (sGHD) patients, trabecular density (mg/cm3) decreased from 214 to 202 (p<0.01); changes in the adolescents with normal test results (tGHD) were from 221 to 214 (p<0.05). Cortical density (mg/cm3) increased from 1077 to 1099 (p<0.01) in sGHD patients and from 1060 to 1082 in tGHD patients (p<0.001). The strength strain index (mm3) showed no significant changes in sGHD patients (306 to 307) but changed from 302 to 315 in tGHD patients (p<0.05). Total bone area (mm2) shifted from 145.1 to 145.2 in sGHD patients and from 153 to 156 in tGHD patients. Total body aBMD (g/cm2) increased in both groups: from 1.10 to 1.12 in sGHD patients and from 1.11 to 1.14 in tGHD patients (p<0.01). All bone measurements remained within the reference ranges, and there were no differences between sGHD and tGHD patients. During a 6-month pause of rhGH treatment, the bone structure and density of adolescents with sGHD did not show changes implying harm. Routine retesting of adolescents, including 6months without GH, is unlikely to be detrimental to the bone.

DXA and pQCT derived parameters in Indian children with beta thalassemia major - A case controlled study.

Children with beta thalassemia major (BTM) are known to have reduced bone mass which increases incidence of non-traumatic fractures. Few studies have assessed prevalence of fractures and bone health in underprivileged children with BTM. Our objectives were to 1) determine prevalence of fractures in underprivileged Indian children with BTM, 2) assess size corrected bone density and bone geometry using Dual x-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT) in these children and healthy controls 3) determine predictors of fractures in children with BTM 4) compare differences in bone density between children with BMT with and without fractures. Bone mineral content and areal bone mineral density (aBMD) of lumbar spine and whole body and vertebral fracture assessment (VFA) was performed by DXA in 334 children (3-18years, 167 BTM+167 controls). Volumetric BMD (vBMD) and bone geometry were assessed by pQCT (subset, 70 BTM, 70 healthy) at distal radius. Children with BTM had higher prevalence of vertebral and long bone fractures (p<0.05). DXA aBMD was lower in children with BTM (p<0.05), whereas, lumbar spine bone mineral apparent density (LSBMAD) was higher (p>0.05). Children with BTM had lower total distal radial vBMD, cortical vBMD and strength strain index (SSI) at 66% site whereas, distal radial trabecular vBMD at 4% was higher (p<0.05). On height adjustment, children with BTM had lower muscle area and cortical thickness and higher marrow area (p<0.05) at 66% site. Age, body size, total body less head (TBLH) aBMD and strength strain index (SSI) were important predictors of fractures in children with BTM. Thus, children with BTM had higher prevalence of non-traumatic fractures. Despite lower areal and volumetric densities, they had higher LSBMAD and trabecular densities which may be attributed to erythroid hyperplasia and iron deposition due to inadequate transfusion and chelation. As LSBMAD is raised in these children, it is unlikely to identify BTM subjects at risk of fracture; VFA thus maybe useful in identifying asymptomatic vertebral fractures.

Influence of Changes in Soft Tissue Composition on Changes in Bone Strength in Peripubertal Girls: The STAR Longitudinal Study.

Obesity and osteoporosis remain two major public health concerns. Soft tissue composition and bone are interrelated; however, it is still not well understood how changes in adiposity during adolescence affect bone development. The aim of this study was to assess how changes in DXA-derived total body lean mass (TBLM) and total body fat mass (TBFM) associate with 2-year changes in bone outcomes at the 20% femur, 66% tibia, 66% radius, and 4% tibia, as measured by pQCT, during the years surrounding the onset of menarche in a cohort of 9- to 12-year-old (baseline) adolescent girls (70% Hispanic). From baseline to 2-year follow-up, girls showed statistically significant increases in all bone outcomes, except radial endosteal circumference. In separate linear regression models, change in TBLM and change in TBFM were both positively associated with 2-year changes in bone outcomes at all measured bone sites, after controlling for relevant covariates. However, when change in TBLM and change in TBFM were included in the same model, change in TBLM was the predominant predictor of bone outcomes, explaining 4% to 14% of the variance in bone strength outcomes. Change in TBFM remained a positive predictor of tibia polar strength strain index (SSIp) (2% variance explained). A significant interaction between change in TBFM and menarcheal status was identified at the radius for SSIp and indicated that greater gains in TBFM were beneficial for SSIp in girls that were premenarcheal at baseline but detrimental for girls who were postmenarcheal at baseline. The overall findings suggest that changes in TBLM during the peripubertal years have a greater influence on bone outcomes than changes in TBFM. While gains in TBFM might benefit the weight bearing 66% tibia, greater gains in TBFM may be detrimental to bone development at the non-weight bearing 66% radius after the onset of menarche. © 2020 American Society for Bone and Mineral Research (ASBMR).