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The age-related maturation of the human midpalatal suture is challenging to predict, but critical for successful non-surgical rapid maxillary expansion (RME). While cone-beam computed tomography (CBCT) can be used to categorize the suture into stages, it remains unclear how well the stages predict the actual micromorphology of the palate. To address this clinically relevant question, we used CBCT together with three-dimensional micro-computed tomography (μCT) analysis on 24 human palate specimens from individuals aged 14–34 years. We first classified the specimens into stages (A-E) using CBCT images and then correlated the results with our comprehensive μCT analysis. Our analysis focused on several factors, including bone volume fraction (BV/TV), sutural width, volume, interdigitation, ossification, and their associations with age, CBCT stage, and sex. Our μCT analysis revealed a decrease in sutural width and volume after the age of 20 years, accompanied by sutural closure beginning in the palatal segment. The overall rate of ossification remained low but increased after the age of 20 years. No significant differences were found between males and females. Importantly, we also found no correlation between individual age and CBCT stages. Furthermore, there was no association between CBCT stages and patalal suture volume, ossification and interdigitation. Taken together, our findings cast doubt on the reliability of CBCT stage as a means of predicting skeletal maturity of the palatal suture, as it appears to lack the precision required to accurately assess the true micromorphology of the palatal suture. Future investigations should explore whether alternative CBCT parameters may be more useful in addressing the challenging question of whether RME requires surgical bone weakening. [Display omitted] • CBCT staging is not related to the micromorphology of the midpalatal suture. • Gender does not influence the anatomy of the midpalatal suture between ages 14 and 34. • Basal sutural width decreases after the age of 20 and is lower in the palatal segment. • Ossification of the midpalatal suture peaks at the end of the third decade of life. • Ossification, interdigitation, volume and width cannot be obtained from CBCT scans. [ABSTRACT FROM AUTHOR]

Patients with bone and muscle loss from prolonged disuse have higher risk of falls and subsequent fragility fractures. In addition, fracture patients with continued disuse and/or delayed physical rehabilitation have worse clinical outcomes compared to individuals with immediate weight-bearing activity following diaphyseal fracture. However, the effects of prior disuse followed by physical reambulation on fracture healing cellular processes and adjacent bone and skeletal muscle recovery post-injury remains poorly defined. To bridge this knowledge gap and inform future treatment and rehabilitation strategies for fractures, a preclinical model of fracture healing with a history of prior unloading with and without reambulation was employed. First, skeletally mature male and female C57BL/6J mice (18 weeks) underwent hindlimb unloading by tail suspension (HLU) for 3 weeks to induce significant bone and muscle loss modeling enhanced bone fragility. Next, mice had their right femur fractured by open surgical dissection (stabilized with 24-gauge pin). Then, mice were randomly assigned to continued HLU or allowed normal weight-bearing reambulation (HLU + R). Mice given normal cage activity throughout the experiment served as healthy age-matched controls. All mice were sacrificed 4-days (DPF4) or 14-days (DPF14) following fracture to assess healing and uninjured hindlimb musculoskeletal properties (6–10 mice per treatment group/biological sex/timepoint). We found that continued disuse following fracture led to severely diminished uninjured hindlimb skeletal muscle mass (gastrocnemius and soleus) and femoral bone volume adjacent to the fracture site compared to healthy age-matched controls across mouse sexes. Furthermore, HLU led to significantly decreased periosteal expansion (DPF4) and osteochondral tissue formation by DPF14, and trends in increased osteoclastogenesis (DPF14) and decreased woven bone vascular area (DPF14). In contrast, immediate reambulation for 2 weeks after fracture, even following a period of prolonged disuse, was able to increase hindlimb skeletal tissue mass and increase osteochondral tissue formation, albeit not to healthy control levels, in both mouse sexes. Furthermore, reambulation attenuated osteoclast formation seen in woven bone tissue undergoing disuse. Our results suggest that weight-bearing skeletal loading in both sexes immediately following fracture may improve callus healing and prevent further fall risk by stimulating skeletal muscle anabolism and decreasing callus resorption compared to minimal or delayed rehabilitation regimens. • Reambulation for 2 Weeks After Disuse and Diaphyseal Fracture Improved But Did Not Recover Uninjured Bone and Muscle Loss • Reambulation for 2 Weeks After Disuse and Diaphyseal Fracture Partially Recovered Osteochondral Callus Formation • Reambulation Improved Early Callus Periosteal Expansion and Decreased Woven Bone Callus Osteoclastogenesis • Reambulation immediately after diaphyseal fracture, even with a prior history of disuse, can improve healing in both biological sexes [ABSTRACT FROM AUTHOR]

Bone age (BA) measurement in children is used to evaluate skeletal maturity and helps in the diagnosis of growth disorders in children. The two most used methods are Greulich and Pyle (GP), and Tanner and Whitehouse 3 (TW3), both based upon assessment of a hand-wrist radiograph. To our knowledge no study has compared and validated the two methods in sub-Saharan Africa (SSA), and only a few have determined BA despite it being a region where skeletal maturity is often impaired for example by HIV and malnutrition. This study aimed to compare BA as measured by two methods (GP and TW3) against chronological age (CA) and determine which method is most applicable in peripubertal children in Zimbabwe. We conducted a cross-sectional study of boys and girls who tested negative for HIV. Children and adolescents were recruited by stratified random sampling from six schools in Harare, Zimbabwe. Non-dominant hand-wrist radiographs were taken, and BA assessed manually using both GP and TW3. Paired sample Student t -tests were used to calculate the mean differences between BA and chronological age (CA) in boys and girls. Bland-Altman plots compared CA to BA as determined by both methods, and agreement between GP and TW3 BA. All radiographs were graded by a second radiographer and 20 % of participants of each sex were randomly selected and re-graded by the first observer. Intraclass correlation coefficient assessed intra- and inter-rater reliability and coefficient of variation assessed precision. We recruited 252 children (111 [44 %] girls) aged 8.0–16.5 years. The boys and girls were of similar mean ± SD CA (12.2 ± 2.4 and 11.7 ± 1.9 years) and BA whether assessed by GP (11.5 ± 2.8 and 11.5 ± 2.1 years) or TW3 (11.8 ± 2.5 and 11.8 ± 2.1 years). In boys BA was lower than CA by 0.76 years (95 % CI: −0.95, −0.57) when using GP, and by 0.43 years (95 % CI: −0.61, −0.24) when using TW3. Among the girls there was no difference between BA and CA by either GP [−0.19 years (95 % CI: −0.40, 0.03)] or TW3 [0.07 years (95 % CI: −0.16, 0.29)]. In both boys and girls, there were no systematic differences between CA and TW3 BA across age groups whereas agreement improved between CA and GP BA as children got older. Inter-operator precision was 1.5 % for TW3 and 3.7 % for GP (n = 252) and intra-operator precision was 1.5 % for TW3 and 2.4 % for GP (n = 52). The TW3 BA method had better precision than GP and did not systematically differ from CA, meaning that TW3 is the preferred method of assessment of skeletal maturity in Zimbabwean children and adolescents. TW3 and GP methods do not agree for estimates of BA and therefore cannot be used interchangeably. The systematic differences in GP BA assessments over age means it is not appropriate for use in all age groups or stages of maturity in this population. • TW3 method is preferred for bone age assessment in Zimbabwean peripubertal children. • TW3 has better precision that GP method in assessing skeletal maturity. • GP and TW3 method may not be used interchangeably in this population. • The boys were less skeletally mature than the girls of the same chronological age. [ABSTRACT FROM AUTHOR]

Spine fusion surgery is one of the most common orthopedic procedures, with over 400,000 performed annually to correct deformities and pain. However, complications occur in approximately one third of cases. While many of these complications may be related to poor bone quality, it is difficult to detect bone abnormalities prior to surgery. Areal BMD (aBMD) assessed by DXA may be artifactually high in patients with spine pathology, leading to missed diagnosis of deficits. In this study, we related preoperative imaging characteristics of both central and peripheral sites to direct measurements of bone quality in vertebral biopsies. We hypothesized that pre-operative imaging outcomes would relate to vertebral bone mineralization and collagen properties. Pre-operative assessments included DXA measurements of aBMD of the spine, hip, and forearm, central quantitative computed tomography (QCT) of volumetric BMD (vBMD) at the lumbar spine, and high resolution peripheral quantitative computed tomography (HRpQCT; Xtreme CT2) measurements of vBMD and microarchitecture at the distal radius and tibia. Bone samples were collected intraoperatively from the lumbar vertebrae and analyzed using Fourier-transform Infrared (FTIR) spectroscopy. Bone samples were obtained from 23 postmenopausal women (mean age 67 ± 7 years, BMI 28 ± 8 kg/m2). We found that patients with more mature bone by FTIR, measured as lower acid phosphate content and carbonate to phosphate ratio, and greater collagen maturity and mineral maturity/crystallinity (MMC), had greater cortical vBMD at the tibia and greater aBMD at the lumbar spine and one-third radius. Our data suggests that bone quality at peripheral sites may predict bone quality at the spine. As bone quality at the spine is challenging to assess prior to surgery, there is a great need for additional screening tools. Pre-operative peripheral bone imaging may provide important insight into vertebral bone quality and may foster identification of patients with bone quality deficits. • BMD was related to material properties of bone in spine surgery patients. • More mature bone by FTIR was associated with greater BMD at cortical sites. • Imaging of peripheral skeletal sites may predict material properties at the spine. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL) tear leads to post-traumatic osteoarthritis (PTOA), a significant clinical burden worldwide that currently has no cure. Recent studies suggest a role of subchondral bone adaptations in the development of PTOA. Particularly, microstructural changes in the rod-and-plate microstructure of subchondral bone may precede and contribute to OA progression. In this study, we quantified microstructural changes in subchondral trabecular rods and plates after ACL-transection for the first time in the well-established preclinical canine model of PTOA and investigated the therapeutic potentials of a bisphosphonate (zoledronate) and NSAID treatment (meloxicam). Unilateral hindlimb ACL transection was performed on skeletally-mature (2-year-old, N = 20) and juvenile (10-month-old, N = 20) male beagles. Animals were assigned to 4 groups (N = 5): ACLT, un-operated control, ACLT with zoledronate, and ACLT with meloxicam treatment. Subchondral bone microstructure was evaluated by micro-computed tomography and cartilage integrity was evaluated histologically. We found that ACL-induced subchondral bone changes depended on skeletal maturity of animals. In mature animals, significant loss of trabecular plates that resulted in reduced PR ratio occurred at Month 1 and persisted until Month 8. Zoledronate treatment prevented trabecular plate loss while meloxicam treatment did not. Whether cartilage degeneration is also attenuated warrants further investigation. In juvenile animals that have not reached skeletal maturity, transient changes in trabecular plate and rod microstructure occurred at Month 3 but not Month 9. Neither zoledronate nor meloxicam treatment attenuated bone microstructural changes or cartilage damages. Findings from this study suggest that early inhibition of bone resorption by bisphosphonate after injury may be a promising therapeutic approach to prevent alterations in subchondral bone microstructure associated with PTOA. Our results further demonstrate that pathogenesis of PTOA may differ between adolescent and adult patients and therefore require distinct management strategies. • ACLT-induced subchondral bone micro-structural changes is dependent on skeletal maturity in canine model. • Zoledronate, instead of meloxicam, is capable to prevent trabecular loss in the mature animals. • Neither zoledronate nor meloxicam can inhibit the bone micro-structural changes or cartilage regeneration in juvenile animals. • Early inhibition of bone resorption by bisphosphonate following ACL-injury provide new clues in preventing subchondral bone degeneration. [ABSTRACT FROM AUTHOR]

Osteoporosis medications have been reported to have beneficial and harmful cardiovascular effects. Much of this evidence stems from single reports and as such, a comprehensive examination of the evidence is needed. We conducted a network meta-analysis (NMA) of cardiovascular adverse event (CAE) data from randomized trials of osteoporosis medications in postmenopausal women. Trials were identified from recent NMAs of osteoporosis treatment for fracture reduction with an updated literature search (December 2020). Included studies were randomized, included over 100 participants, and reported skeletal primary outcomes. We investigated three-point major adverse cardiovascular events (MACE3), four- (MACE4) and five-point MACE (MACE5), as well as myocardial infarction (MI) and stroke. Data were synthesized in a random-effects network meta-analysis using Bayesian modelling. Probabilistic ranking of treatment safety was performed. Relative to placebo, point estimates for the odds ratios (OR) with 95 % credible intervals (CrI) were also generated. We identified 75 trials (n = 136,940 women), of which 27 (68,699 women, nine arms) reported CAEs. In women randomized to placebo, the overall event rate for the MACE3 outcome was 2.58 % compared with 1.99 % in those randomized to all other active comparators. Probabilistic ranking found abaloparatide, oral bisphosphonates, teriparatide, and menopausal hormone therapy were less likely to have increased risk of CAEs than placebo, while romosozumab ranked more likely to have increased risk of CAEs than placebo for all outcomes. Compared with placebo, abaloparatide (one trial, n = 1642) was associated with a reduced odds for MACE3 (OR = 0·31; 95%CrI: 0·06 to 0·99), MACE4 (0·28; 0·06 to 0·88) and MACE5 (0·25; 0·06 to 0·79). When all PTH analogues were grouped together, magnitude and direction of effects were consistent but no longer statistically significant. We did not find pooled direct and indirect evidence that osteoporosis treatments significantly increased the risk of adverse cardiovascular events relative to placebo. (PROSPERO: CRD42020178702). • 75 trials with 27 providing cardiovascular safety event rates for analysis • Abaloparatide, oral bisphosphonates, teriparatide & MHT 'safer' than placebo • Romosozumab and denosumab ranked 'more harmful' than placebo. • These data may guide conversations about nonskeletal effects of osteoporosis drugs. [ABSTRACT FROM AUTHOR]

The assessment of fracture risk often relies primarily on measuring bone mineral density, thereby accounting for only a single pathology: the loss of bone mass. However, bone's ability to resist fracture is a result of its biphasic composition and hierarchical structure that imbue it with high strength and toughness. Reference point indentation (RPI) testing is designed to directly probe bone mechanical behavior at the microscale in situ , although it remains unclear which aspects of bone composition and structure influence the results at this scale. Therefore, our goal in this study was to investigate factors that contribute to bone mechanical behavior measured by cyclic reference point indentation, impact reference point indentation, and three-point bending. Twenty-eight female cadavers (ages 57–97) were subjected to cyclic and impact RPI in parallel at the unmodified tibia mid-diaphysis. After RPI, the middiaphyseal tibiae were removed, scanned using micro-CT to obtain cortical porosity (Ct.Po.) and tissue mineral density (TMD), then tested using three-point bending, and lastly assayed for the accumulation of advanced glycation end-products (AGEs). Both the indentation distance increase from cyclic RPI (IDI) and bone material strength index from impact RPI (BMSi) were significantly correlated with TMD (r = − 0.390, p = 0.006; r = 0.430, p = 0.002; respectively). Accumulation of AGEs was significantly correlated with IDI (r = 0.281, p = 0.046), creep indentation distance (CID, r = 0.396, p = 0.004), and BMSi (r = − 0.613, p < 0.001). There were no significant relationships between tissue TMD or AGEs accumulation with the quasi-static material properties. Toughness decreased with increasing tissue Ct.Po. (r = − 0.621, p < 0.001). Other three-point bending measures also correlated with tissue Ct.Po. including the bending modulus (r = − 0.50, p < 0.001) and ultimate stress (r = − 0.56, p < 0.001). The effects of Ct.Po. on indentation were less pronounced with IDI (r = 0.290, p = 0.043) and BMSi (r = − 0.299, p = 0.037) correlated modestly with tissue Ct.Po. These results suggest that RPI may be sensitive to bone quality changes relating to collagen. [ABSTRACT FROM AUTHOR]

Growth is the opportune time to modify bone accrual. While bone adaptation is known to be dependent on local loading and consequent deformations (strain) of bone, little is known about the effects of sex, and bone-specific physical activity on location-specific cross-sectional bone geometry during growth. To provide more insight we examined bone traits at different locations around tibial cross sections, and along the tibia between individuals who vary in terms of physical activity exposure, sex, and pubertal status. Data from 304 individuals aged 5–29 years (172 males, 132 females) were examined. Peripheral quantitative computed tomography (pQCT) was applied at 4%, 14%, 38%, and 66% of tibial length. Maturity was established by estimating age at peak height velocity (APHV). Loading history was quantified with the bone-specific physical activity questionnaire (BPAQ). Comparisons, adjusted for height, weight and age were made between sex, maturity, and BPAQ tertile groups. Few to no differences were observed between sexes or BPAQ tertiles prior to APHV, whereas marked sexual dimorphism and differences between BPAQ tertiles were observed after APHV. Cross-sectional location-specific differences between BPAQ tertiles were not evident prior to APHV, whereas clear location-specificity was observed after APHV. In conclusion, the skeletal benefits of physical activity are location-specific in the tibia. The present results indicate that the peri- or post-pubertal period is likely a more favourable window of opportunity for enhancing cross-sectional bone geometry than pre-puberty. Increased loading during the peri-pubertal period may enhance the bone of both sexes. [ABSTRACT FROM AUTHOR]

Background Little is known about the effects of adrenal steroids on skeletal maturation and bone mass acquisition in healthy prepubertal boys. Objective To study whether adrenal-derived steroids within the physiological range are associated with skeletal maturation, areal and volumetric bone mineral density (aBMD and vBMD) and bone geometry in healthy prepubertal and early pubertal boys. Methods 98 healthy prepubertal and early pubertal boys (aged 6–14 y) were studied cross-sectionally. Androstenedione (A) and estrone (E1) were determined by liquid chromatography tandem mass spectrometry and DHEAS was determined by immunoassay. Whole body and lumbar spine aBMD and bone area were determined by dual-energy X-ray absorptiometry. Trabecular (distal site) and cortical (proximal site) vBMD and bone geometry were assessed at the non-dominant forearm and leg using peripheral QCT. Skeletal age was determined by X-ray of the left hand. Results Adrenal-derived steroids (DHEAS, A and E1) are positively associated with bone age in prepubertal and early pubertal children, independently of age. There are no associations between the adrenal-derived steroids and the studied parameters of bone size (lumbar spine and whole body bone area, trabecular or cortical area at the radius or tibia, periosteal circumference and cortical thickness at the radius or tibia) or BMD (aBMD or vBMD). Conclusion In healthy prepubertal and early pubertal boys, serum adrenal-derived steroid levels, are associated with skeletal maturation, independently of age, but not with bone size or (v)BMD. Our data suggest that adrenal derived steroids are not implicated in the accretion of bone mass before puberty in boys. [ABSTRACT FROM AUTHOR]

Abstract: Background: Prior studies have identified some risk factors for stress fracture in athletes and military recruits. Objective: To determine whether historical factors, physical measures, biochemical variables of skeletal metabolism, genetic factors, bone density (BMD) and bone size could predict risk of stress fracture over 4years in physically fit cadets at the US Military Academy (USMA). Methods: Baseline surveys, assessments of height, weight, scores on the Army Physical Fitness Test, and peripheral BMD were obtained in all cadets (755 men, 136 women), and central BMD in a subset. Blood samples were analyzed for variables of calcium homeostasis, bone turnover, and selected hormones and genetic factors. Stress fractures were adjudicated by review of orthopedic notes and imaging reports. Results: 5.7% of male and 19.1% of female cadets had at least 1 stress fracture (58% metatarsal and 29% tibial), most within 3months of entry to USMA. In males, risk of stress fracture was higher in those who exercised <7h per week during the prior year (RR 2.31; CI 1.29,4.12), and in those with smaller tibial cortical area (RR 1.12; CI 1.03,1.23), lower tibial bone mineral content (RR 1.11; CI 1.03,1.20) and smaller femoral neck diameter (RR 1.35, CI 1.01, 1.81). In women, higher stress fracture risk was seen in those with shorter time since menarche (RR 1.44 per year; CI 1.19, 1.73) and smaller femoral neck diameter (RR 1.16; CI 1.01, 1.33.). Conclusion: Although prior physical training in men, length of prior estrogen exposure in women and leg bone dimensions in both genders played a role, the maximum variance explained by all of these factors was below 10%. We conclude these factors play a minor role in the development of stress fractures in physically fit USMA cadets. [Copyright &y& Elsevier]

Abstract: The variation of skeletal maturity about chronological age is a sensitive indicator of population health. Age appropriate or advanced skeletal maturity is a reflection of adequate environmental and social conditions, whereas delayed maturation suggests inadequate conditions for optimal development. There remains a paucity of data, however, to indicate which specific biological and environmental factors are associated with advancement or delay in skeletal maturity. The present study utilises longitudinal data from the South African Birth to Twenty (Bt20) study to indentify predictors of relative skeletal maturity (RSM) in early adolescence. A total of 244 black South African children (n=131 male) were included in this analysis. Skeletal maturity at age 9/10years was assessed using the Tanner and Whitehouse III RUS technique. Longitudinal data on growth, socio-economic position and pubertal development were entered into sex-specific multivariable general linear regression models with relative skeletal maturity (skeletal age-chronological age) as the outcome. At 9/10years of age males showed an average of 0.66years delay in skeletal maturation relative to chronological age. Females showed an average of 1.00year delay relative to chronological age. In males, being taller at 2years (p<0.01) and heavier at 2years (p<0.01) predicted less delay in RSM at age 9/10years, independent of current size and body composition. In females, both height at 2years and conditional weight at 2years predicted less delay in RSM at 9/10years (p<0.05) but this effect was mediated by current body composition. Having greater lean mass at 9/10years was associated with less delayed RSM in females (p<0.01) as was pubertal status at the time of skeletal maturity assessment (p<0.01). This study identifies several predictors of skeletal maturation at 9/10years, indicating a role for early life exposures in determining the rate of skeletal maturation during childhood independently of current stature. [Copyright &y& Elsevier]

Abstract: Achondroplasia (ACH), the most common form of human dwarfism is caused by a mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, resulting in constitutive activation of the receptor. Typical radiological features include shortening of the tubular bones and macrocephaly, due to disruption of endochondral ossification. Consequently, FGFR3 has been described as a negative regulator of bone growth. Studying a large cohort of ACH patients, a delay in bone age was observed shortly after birth (for boys p =2.6×10−9 and for girls p =1.2×10−8). This delay was no longer apparent during adolescence. In order to gain further insight into bone formation, bone development was studied in a murine model of chondrodysplasia (Fgfr3 Y367C/+ ) from birth to 6weeks of age. Delayed bone age was also observed in Fgfr3 Y367C/+ mice at 1week of age followed by an accelerated secondary ossification center formation. A low level of chondrocyte proliferation was observed in the normal growth plate at birth, which increased with bone growth. In the pathological condition, a significantly high level of proliferative cells was present at birth, but exhibited a transient decrease only to rise again subsequently. Histological and in situ analyses suggested the altered endochondral ossification process may result from delayed chondrocyte differentiation, disruption of vascularization and osteoblast invasion of the femur. All these data provide evidence that FGFR3 regulates normal chondrocyte proliferation and differentiation during bone growth and suggest that constitutive activation of the receptor disrupts both processes. Therefore, the consequences of FGFR3 activation on the physiological process of bone development appear to be dependent on spatial and temporal occurrence. In conclusion, these observations support the notion that FGFR3 has a dual effect, as both a negative and a positive regulator of the endochondral ossification process during post-natal bone development. [Copyright &y& Elsevier]

Abstract: Important aspects of bone tissue quality include the physicochemical properties of its main constituents, the organic matrix and the mineral crystals. One of the most commonly reported measurements of Raman analysis of bone is the mineral to matrix ratio, obtained from the ratio of the integrated areas of any of the phosphate and amide peaks which depend on both tissue organization and composition. Cube-like samples of normal mouse cortical bone taken from the diaphysis and metaphysis of the femur were investigated within different age groups (2, 4, 8 and 12weeks) by Raman microspectroscopy. Anatomically identical bone in both longitudinal and transverse directions was analyzed, enabling the discrimination between orientation and composition changes both as a function of animal age, and tissue age within the same animal. The results of the present study indicate that there is a parallel evolution of both orientation and chemical composition as a function of animal age, as well as tissue age within the same specimen. Our tissue age modified ratio of the carbonate to phosphate Raman peaks suggests that the bone mineral crystallite maturity remains relatively constant with animal age. Comparisons of polarized and depolarized experiments in the transversal plane of the diaphysis show a lack of orientation effects as a function of tissue age within the same animal, but exhibit differences as a function of animal age. In the metaphysis, the orientation effect is evident too, albeit less pronounced. This is most likely due to either the age difference between the two tissues within the same specimen in the long bone axis, as metaphyseal bone is generally younger than diaphyseal, or the more random orientation of the tissue collagen itself. [Copyright &y& Elsevier]

Abstract: As computational modeling becomes an increasingly common tool for probing the regulation of bone remodeling, the need for experimental data to refine and validate such models also grows. For example, van Oers et al. (R.F. van Oers, R. Ruimerman, B. van Rietbergen, P.A. Hilbers, R. Huiskes, Relating osteon diameter to strain. Bone 2008;43: 476–482.) recently described a mechanism by which osteon size may be regulated (inversely) by strain. Empirical data supporting this relation, particularly in humans, are sparse. Therefore, we sought to determine if there is a link between body weight (the only measure related to loading available for a cadaveric population) and osteon geometry in human bone. We hypothesized that after controlling for age, sex and height, weight would be inversely related to femoral osteon size (area, On.Ar; diameter, On.Dm). Secondarily we sought to describe the relation between osteon circularity (On.Cr) and these parameters. Osteons (n =12,690) were mapped within microradiographs of femoral mid-diaphyseal specimens (n =88; 45 male, 43 female; 17–97 yrs). Univariate analysis of covariance was conducted (n =87; 1 outlier) with sex as a fixed factor and height, weight and log-transformed age as covariates. Weight was negatively related to On.Ar and On.Dm (p =0.006 and p =0.004, respectively). Age was significantly related to osteon and, it was also significantly related to circularity (all p <0.001). This relation was negative for On.Ar and On.Dm and positive for On.Cr (increasing circularity with age). On.Ar and On.Dm were found to be significantly different between the sexes (p =0.021 and p =0.019, respectively), with females having smaller osteons. No relation between sex and On.Cr was detected (p =0.449). Height was not significantly related to any of the geometric parameters. Partial eta-squared values revealed that age accounted for the largest proportion (On.Ar: 28%, On.Dm: 18%, On.Cr: 30%), weight accounted for the second largest (On.Ar: 9%, On.Dm: 10%) and sex accounted for the smallest proportion (On.Ar: 6%, On.Dm: 7%) of the variance in geometry. While previous studies have reported relations between osteon size and sex/age, we believe that our findings are the first to demonstrate a link with weight. We believe that this negative relation with weight is most probably mechanical in nature; however, alternative (endocrine) links between bone and adipose tissue cannot be ruled out by our design. [Copyright &y& Elsevier]

Abstract: Peak bone mass (PBM) is an important determinant of osteoporosis. Circulating monocytes serve as early progenitors of osteoclasts and produce important molecules for bone metabolism. To search for genes functionally important for PBM variation, we performed a whole genome gene differential expression study of circulating monocytes in human premenopausal subjects with extremely low (N =12) vs. high (N =14) PBM. We used Affymetrix HG-U133 plus2.0 GeneChip® arrays. We identified 70 differential expression probe sets (p <0.01) corresponding to 49 unique genes. After false discovery rate adjustment, three genes [STAT1, signal transducer and activator of transcription 1; GBP1, guanylate binding protein 1; CXCL10, Chemokine (C-X-C motif) ligand 10] expressed significantly differentially (p <0.05). The RT-PCR results independently confirmed the significantly differential expression of GBP1 gene, and the differential expression trend of STAT1. Functional analyses suggested that the three genes are associated with the osteoclastogenic processes of proliferation, migration, differentiation, migration, chemotaxis, adhesion. Therefore, we may tentatively hypothesize that the three genes may potentially contribute to differential osteoclastogenesis, which may in the end lead to differential PBM. Our results indicate that the GBP1, STAT1 and CXCL10 may be novel risk genes for the differentiation of PBM at the monocyte stage. [Copyright &y& Elsevier]

Abstract: Some studies have reported that after attainment of peak bone mass (PBM), slow bone loss may occur in both men and women; however, findings are inconsistent. Genetic factors play a significant role in bone loss, but the available evidence is conflicting. Genetic lactase non-persistence (lactase C/C−13910 genotype) is suggested to increase risk for inadequate calcium intake predisposing to poorer bone health. We investigated whether this genotype is associated with PBM and bone loss in young Finnish adults. Subjects belong to the Cardiovascular Risk in Young Finns Study that is an ongoing multi-centre follow-up of atherosclerosis risk factors. From the original cohort, randomly selected subjects aged 20–29 participated in baseline bone mineral density (BMD) measurements (n =358), and in follow-up measurements 12 years later (n =157). Bone mineral content (BMC) and BMD at lumbar spine (LS) and femoral neck (FN) were measured at baseline and follow-up with dual energy X-ray absorptiometry (DXA). Lactase C/T−13910 polymorphism was determined by PCR and allele-specific fluorogenic probes. Information on lifestyle was elicited with questionnaires. During the follow-up, bone loss at both bone sites was greater in males (LS BMD: −1.1%, FN BMD: −5.2%) than in females (LS BMD: +2.1%, FN BMD: −0.7%) (both bone sites p =0.001). Younger age predicted greater loss of FN BMC and BMD in females (p =0.013 and p =0.001, respectively). Increased calcium intake predicted FN BMD gain in both sexes (in females B =0.007 g/cm2/mg, p =0.002; in males B =0.006, p =0.045), and increased physical activity LS BMD gain in females (B =0.091 g/cm2/physical activity point, p =0.023). PBM did not differ between the lactase genotypes, but males with the CC−13910 genotype seemed to be prone to greater bone loss during the follow-up (LS BMD: C/C vs. T/T p =0.081). In conclusion, bone loss in young adulthood was more common in males than in females and seemed to occur mainly at the femoral neck. Young males with the lactase CC−13910 genotype may be more susceptible to bone loss; however, calcium intake predicts changes in bone mass more than the lactase genotype. [Copyright &y& Elsevier]

Abstract: MLO-A5 cells are a fully differentiated osteoblastic cell line with the ability to rapidly synthesise mineralised extracellular matrix (ECM). We used MLO-A5 cells to develop a system for studying the mechanical modulation of bone matrix formation in 3D using a cyclic compressive loading stimulus. Polyurethane (PU) open cell foam scaffolds were seeded with MLO-A5 cells under static conditions and loaded in compression at 1 Hz, 5% strain in a sterile fluid-filled chamber. Loading was applied for only 2 h per day on days 5, 10 and 15 of culture and cell-seeded scaffolds were assayed on days 10, 15 and 20 of culture. Collagen content as assayed by Sirius red was significantly (2 fold) higher at days 15 and 20 in loaded samples compared with static controls. Calcium content as assayed by alizarin red was significantly (4 fold) higher by day 20. The number of viable cells as assayed by MTS was higher in loaded samples at day 10 but there was no difference by days 15 and 20. Loaded samples also had higher stiffness in compression by the end of the experiment. The mRNA expression of type I collagen, osteopontin and osteocalcin was higher, after a single bout of loading, in loaded than in non-loaded samples as assayed by RT-PCR. In conclusion, mineralisation by fully differentiated osteoblasts, MLO-A5s, was shown to be highly sensitive to mechanical loading, with short bouts of mechanical loading having a strong effect on mineralised matrix production. The 3D system developed will be useful for systematic investigation of the modulators of in vitro matrix mineralisation by osteoblasts in mechanobiology and tissue engineering studies. [Copyright &y& Elsevier]

Abstract: Estrogen affects skeletal growth and promotes growth plate fusion in humans. High doses of estrogen have been used to limit growth in girls with predicted extreme tall stature; a treatment which has been associated with severe side effects. Selective estrogen receptor modulators (SERMs) could potentially be used as an alternative treatment. We chose to study the effects of Tamoxifen (Tam), a first generation SERM that has been used in the treatment of pubertal gynecomastia or McCune–Albright syndrome. Cultured fetal rat metatarsal bones were used to study the effects of Tam on longitudinal bone growth. In sectioned bones, chondrocyte apoptosis and proliferation were analyzed by TUNEL assay and BrdU incorporation, respectively. We also used a human chondrocytic cell line, HSC-2/8, to study the effects of Tam on apoptosis (FACS analysis and Cell Death detection ELISA) and caspase activation (caspase substrate cleavage and Western immunoblotting). Tam caused a dose-dependent growth retardation of cultured metatarsal bones. No catch-up growth was observed after Tam was removed from the culture medium. Detailed analysis of sectioned growth plate cartilage revealed increased apoptosis of chondrocytes within the resting and hypertrophic zones. HCS-2/8 cells also underwent apoptosis upon Tam treatment. Tam-induced apoptosis was caspase-dependent and completely abrogated by either caspase-8 or -9 inhibitors. A substrate assay revealed that caspase-8 is first activated followed by caspase-9 and -3. Finally, FasL secretion was stimulated by Tam and blocking of either FasL or Fas decreased Tam-induced apoptosis in chondrocytes. We here describe a novel mechanism of tamoxifen-induced apoptosis in chondrocytes, involving the activation of caspases and the FasL/Fas pathway, which diminishes the potential for bone growth. [Copyright &y& Elsevier]

Abstract: With age, alterations occurring in bone quality, quantity, and microarchitecture affect the resistance of trabecular bone to local failure. The clinical implications of these changes are evident by the observed exponential increase in fracture incidence with age. Although age-related development of skeletal fragility is well established, it is unclear how the local failure properties of bone change with age. We previously reported a specimen-specific technique to assess microstructural stresses and strains associated with microdamage initiation but did not assess age-related changes. In this study, we compared younger (average age 2 years) and older (average age 10 years) bovine trabecular bone to evaluate how alterations in bovine bone quantity and quality with age affect the local mechanical environment associated with microdamage formation. The results show strong positive correlations between microdamage and local stresses and strains for both younger and older bovine trabecular bone. Correlation strength was slightly improved (<8%) for some parameters by incorporating heterogeneous local material properties based on mineral density into the finite element models. Within individual trabeculae, average stresses and strains were significantly higher in microdamaged trabeculae compared to randomly selected undamaged trabeculae, regardless of age. However, damaged trabeculae in older bone were found to have higher stresses and lower strains than those from younger bone. Corresponding differences in mineral density, microarchitecture, and FEM-determined local material properties were also observed between the two groups. Taken together, these data suggest marked age-related changes in the mechanics of microdamage initiation at the trabecular level. The combined experimental, computational, and histochemical approaches used in this study provide an improved understanding of microdamage initiation and bone quality. [Copyright &y& Elsevier]

Abstract: Bone morphogenic proteins (BMPs) are growth factors important for skeletal development and bone growth. Noggin, one of the soluble BMP antagonists, regulates the action of BMPs on mesenchymal precursor cells, partially through a feedback type of inhibition. In this study, we constructed a novel BMP2/7 ‘fusion gene’ that encodes both BMP2 and BMP7 genes in tandem by a linker. Polymerase chain reaction (PCR) and Western blotting showed that the BMP2/7 fusion gene construct led to the production of BMP2/7 heterodimers in A549 ‘producer’ cells. When applied to C2C12 myoblastic cells, BMP2/7 heterodimers increased alkaline phosphatase (ALP) activity and osteocalcin (OCN) expression (markers of osteoblastic differentiation) more effectively than either BMP2 or BMP7 homodimers. Moreover, this heterodimer induced significantly lower levels of Noggin expression in C2C12 cells than respective homodimers at similar doses. The addition of Noggin did not affect the heterodimer''s activities in increasing osteoblastic differentiation in C2C12 cells. In contrast, BMP2 and BMP7 homodimers were largely inhibited by Noggin. Our finding suggests that the ‘fusion gene’ construct led to the production of bioactive BMP2/7 heterodimers, which were not antagonized by Noggin as effectively as it to BMP homodimers. The weaker Noggin antagonism on BMP heterodimers compared to homodimers may contribute to increased osteogenic potency of heterodimers in vitro and in vivo. [Copyright &y& Elsevier]

Abstract: Loading of the femoral neck (FN) is dominated by bending and compressive stresses. We hypothesize that adaptation of the FN to physical activity would be manifested in the cross-sectional area (CSA) and section modulus (Z) of bone, indices of axial and bending strength, respectively. We investigated the influence of physical activity on bone strength during adolescence using 7 years of longitudinal data from 109 boys and 121 girls from the Saskatchewan Paediatric Bone and Mineral Accrual Study (PBMAS). Physical activity data (PAC-Q physical activity inventory) and anthropometric measurements were taken every 6 months and DXA bone scans were measured annually (Hologic QDR2000, array mode). We applied hip structural analysis to derive strength and geometric indices of the femoral neck using DXA scans. To control for maturation, we determined a biological maturity age defined as years from age at peak height velocity (APHV). To account for the repeated measures within individual nature of longitudinal data, multilevel random effects regression analyses were used to analyze the data. When biological maturity age and body size (height and weight) were controlled, in both boys and girls, physical activity was a significant positive independent predictor of CSA and Z of the narrow region of the femoral neck (P < 0.05). There was no independent effect of physical activity on the subperiosteal width of the femoral neck. When leg length and leg lean mass were introduced into the random effects models to control for size and muscle mass of the leg (instead of height and weight), all significant effects of physical activity disappeared. Even among adolescents engaged in normal levels of physical activity, the statistically significant relationship between physical activity and indices of bone strength demonstrate that modifiable lifestyle factors like exercise play an important role in optimizing bone strength during the growing years. Physical activity differences were explained by the interdependence between activity and lean mass considerations. Physical activity is important for optimal development of bone strength. [Copyright &y& Elsevier]

Abstract: Intravenous treatment with pamidronate is beneficial in children and adolescents with moderate to severe forms of osteogenesis imperfecta (OI) types I, III and IV, but there is little information on the effects of this treatment on the newly described OI type V. Here, we describe the results of 2 years of pamidronate treatment in 11 children and adolescents with OI type V (age at start of therapy 1.8 to 15.0 years; 6 girls). Pamidronate was given in intravenous cycles at a cumulative yearly dose of 9 mg/kg. The first infusion cycle was associated with fever and mild hypocalcemia in most patients, but no other short-term side effects were noted. Two years of pamidronate treatment led to a decrease in the urinary excretion of N-terminal telopeptide of type I collagen to 50% of baseline levels. Both the size and volumetric bone mineral density of lumbar vertebrae increased compared to age- and sex-matched reference data (P < 0.05 in both cases). Histomorphometry of transiliac bone samples showed an average increase of 86% in cortical thickness (N = 7; P = 0.005). No significant changes with treatment were observed in the age-related z scores of isometric maximal grip force and height. Fracture incidence decreased from 1.5 fractures per year before treatment to 0.5 fractures per year during the fist 2 years of treatment. Ambulation status improved in four patients and remained unchanged in the others. In conclusion, the intravenous pamidronate therapy has a similar effect in OI type V as it has in the other OI types. [Copyright &y& Elsevier]

Abstract: Human/murine X-linked hypophosphatemia is a dominant disorder associated with renal phosphate wasting and defective bone mineralization. This disorder results from mutations in the PHEX/Phex (Phosphate-regulating gene with homologies to endopeptidases on the X chromosome) gene, which is expressed in fully differentiated osteoblasts. The purpose of the present study was to assess whether PTH, a major regulator of bone development and turnover, modulates osteoblastic Phex expression. The effects of different concentrations of PTH (rat fragment 1–34) were determined on Phex mRNA and protein expression in vitro using MC3T3-E1 osteoblastic cells and mouse primary osteoblasts; and in vivo using 45-day-old mice infused for 3 days with PTH. Phex mRNA levels were quantitated on Northern blots by densitometric analysis relative to GAPDH mRNA levels. Phex protein levels were analyzed by immunoprecipitation of 35S-methionine-labeled osteoblast lysates or by immunoblotting of calvaria membrane extracts using a polyclonal rabbit antiserum raised against a mouse Phex carboxy-terminal peptide. Fully differentiated MC3T3-E1 cells were incubated for 4 to 48 h with increasing concentrations of PTH (10−11 to 10−7 M). PTH inhibited Phex mRNA expression in both mineralizing and nonmineralizing osteoblast cultures in a dose- and time-dependent manner with a maximal inhibition at 10−7 M PTH after 24 h (15 ± 7% of control levels, n = 5, P &#60; 0.001). The PTH-mediated downregulation of Phex mRNA levels was associated with corresponding decreases in Phex protein synthesis and suppression at 10−7 M PTH. Similar results were obtained with primary osteoblasts isolated from newborn mouse calvaria. Consistent with the in vitro findings, continuous PTH infusion to mice elicited decreases in Phex expression in calvaria. The effect of PTH was also assessed on matrix mineralization by mature MC3T3-E1 cells by measuring 45Ca accumulation in cell layers. PTH (10−7 M) inhibited the initiation (57 ± 2% of control levels, n = 5, P &#60; 0.001) and the progression of matrix mineralization (75 ± 1% of control levels, n = 5, P &#60; 0.001). In summary, PTH inhibits osteoblastic Phex expression in vitro and in vivo. The downregulation of Phex expression by PTH in vitro is associated with inhibition of matrix mineralization, consistent with a role for Phex in bone mineralization. [Copyright &y& Elsevier]

Abstract: Bone formation and remodeling in vivo can be assessed by polychrome labeling using calcium-binding fluorescent dyes. The number of fluorochromes, however, limits this technique due to the fact that with increasing number, fluorescent spectra inevitably overlap, which makes discrimination more difficult. In order to enhance discrimination, we performed spectral image analysis. Non-critical size defects of the femur of male Wistar rats served as a model for bone formation. Eight different fluorochromes (calcein blue, xylenol orange, calcein, alizarine complexone, doxycycline, rolitetracycline, hematoporphyrin, and BAPTA) were administered sequentially subcutaneously every third day starting at day 4 after surgery. Following, bone specimen were embedded in methylmethacrylate and analyzed by spectral image acquisition using a Sagnac type interferometer (ASI, Israel). Seven of the eight applied fluorochromes could be resolved using spectral image examination. With BAPTA, we present a new fluorochrome suitable for bone labeling. Due to the superior sensitivity of the spectral image acquisition, the thickness of the bone sections could be reduced so that 5 μm thick sections could be analyzed. Spectral decomposition and subsequent linear unmixing allows depiction of each individual fluorochrome without interference of any other, enabling a reliable and superior morphometric analysis of labeled regions. [Copyright &y& Elsevier]

Abstract: During growth, bone strength is conferred through subtle adaptations in bone mass and geometry in response to muscle forces. Few studies have examined the changes in bone geometry, strength and the bone–muscle strength relationship across maturity in boys and girls. Our aims were to describe (i) 20-month changes in bone geometry and strength at the tibial midshaft across three maturity groups of boys and girls, (ii) differences in these adaptations between sexes at the same approximate level of maturity and (iii) the bone–muscle strength relationship across maturity groups of boys and girls and between sexes. We used peripheral quantitative computed tomography (pQCT, Stratec XCT-2000) to measure change in total bone cross-sectional area (ToA, mm2), cortical area (CoA, mm2), average cortical thickness (C.Th., mm), section modulus (mm3) and muscle cross-sectional area (mm2) at the tibial midshaft (50% site) in 128 EARLY-, PERI- and POST-pubertal girls (n = 69, 11.9 ± 0.6 years) and boys (n = 59, 12.0 ± 0.6 years) across 20 months. We also calculated two bone–muscle strength indices (BMSI) for compression (CoA/MCSA) and bending [strength index/MCSA; where strength index = Z / (tibial length / 2)]. EARLY boys and girls had smaller ToA at baseline than same sex PERI or POST participants. There were no sex differences in ToA or CoA at baseline; however, boys increased both parameters significantly more than girls in every maturity group (8.5–11.1%, P &#60; 0.01). These changes in bone geometry conferred greater gains in bone strength for boys compared with girls in each maturity group (13.8–15.6%, P &#60; 0.01). Baseline BMSIs did not differ between sexes for EARLY and PERI groups, whereas BMSIs were significantly higher for POST boys compared with POST girls (P &#60; 0.05). BMSIs decreased for EARLY and PERI girls (−7.4–(−1.1%)) whereas the ratios remained stable for EARLY and PERI boys (−0.6–2.5%). This sex difference in BMSI change was due to a relatively greater increase in CoA among EARLY and PERI boys compared with same-maturity girls. BMSIs remained stable in POST girls and decreased in POST boys due to relatively greater gains in MCSA. This study provides novel longitudinal descriptions of the maturity- and sex-specific changes in bone geometry, strength and bone–muscle strength indices. [Copyright &y& Elsevier]

Abstract: The aim of this population-based case-control study was to describe the association among skeletal age deviation (SAD), bone density, and upper limb fracture risk in male and female children aged 9–16 years. A total of 321 fracture cases and 321 randomly selected individually matched controls were studied. Skeletal age was assessed by standard atlas. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) and metacarpal index (MI). There were no significant differences in mean skeletal age or chronological age between fracture cases and controls. However, SAD was associated with total, hand, and female fracture risk (all P &#60; 0.05). The fracture associations became nonsignificant after adjustment for BMD and MI in all subgroups with the exception of hand fractures (OR, 0.67/year; 95% CI, 0.47–0.96). SAD was also positively associated with BMD at all sites (r = 0.33–0.35, all P &#60; 0.05) and MI (r = 0.20, P &#60; 0.05). The strength of association reduced but remained significant at most sites after adjustment for body size, maturity, age, and sex. In conclusion, SAD is positively associated with measures of bone strength and negatively associated with upper limb fracture risk (especially those of the hand) in children. SAD is simple to measure and gives additional information regarding bone health and fracture risk in children. [Copyright &y& Elsevier]

Abstract: Bladder exstrophy patients with or without augmentation have not been investigated according to metabolic bone problems, bone ages and growth, and development in details yet. We studied alterations in growth, bone ages, biochemistry of bone, bone mineral densities (BMD) of the forearm, neck of femur and lumbar vertebrae, blood gases, glomerular filtration rates (GFR), and electrolytes of 15 bladder exstrophy patients with augmentation and in those who had no augmentation. In six patients, a sigmoid colon was used for bladder augmentation and one patient underwent a ureterosigmoidostomy. Growth charts of all children were analyzed for determination of the percentiles. The parameters were compared with normal children and a comparison between augmented and nonaugmented patients were made. Growth retardation and decreased bone age were detected in all of the children. Ten patients with bladder exstrophy were below the 10th percentile for height. The mean age/bone age ratio of the patients was 1.59. The mean lumbar and femoral Z scores of the patients were −1.00 and −0.49, respectively. Mean BMD for distal radius was 0.239 g/cm2. Seven patients had a marked BMD decrease, their femoral and/or lumbar Z scores were below −1. Four cases had a pH lower than 7.35. In five patients, a HCO3 level less than 19 mmol/l was detected, four of them had an augmentation. Chloride measurements were slightly increased in six patients and alkaline phosphatase levels in five cases. Reduced GFR values were detected in two patients. There were no significant difference in laboratory values, in percentile height, and weights, in BMDs of femur, vertebra, forearm nor were any differences noted in age/bone age ratios in patients with augmentation when compared with those who had no augmentation. We found varying alteration in bone mineral density and HCO3 levels in patients with bladder exstrophy. Patients with bladder exstrophy, with or without augmentation, may develop serious growth retardation. As much as 45% of them, regardless of presence of augmentation, have an osteopenia or osteoporosis. We found a considerable difference in percentiles of heights as well as bone ages in bladder exstrophy patients when compared with normal population. We recommend close follow up of children with bladder exstrophy for linear growth, development of osteopenia, and bone ages. [Copyright &y& Elsevier]

The effects of natural aging on the mechanics of the spine are far better understood for the mature adult spine than for the developing (immature) spine. Throughout its chondrification and ossification, the vertebra, which is the primary structural unit of the spine, undergoes enormous cellular, biochemical, and structural changes that should strongly influence its biomechanical response to external forces. Unfortunately, very little data exist for the mechanics of immature vertebrae. Vertebral maturation was therefore investigated in 22 baboon thoracic specimens to elucidate its relationship with biomechanics and volumetric bone mineral density (vBMD). Cadaveric baboon vertebrae were used due to the limited availability of human tissues in the pediatric age range. The specimen ages ranged between 1 and 30 human-equivalent years based on skeletal maturity. Isolated ninth thoracic vertebrae (T9) were subjected to compressive loading to document their compressive mechanical properties (yield load, stiffness, yield strength, and elastic modulus) and ashed to determine their volumetric bone mineral density. Spinal maturation was discovered to significantly increase vBMD (P < 0.0001) and compressive mechanics (stiffness, bulk elastic modulus, failure load, and bulk strength, P < 0.001) in a sex-dependent manner. Vertebral stiffness increased from 1218 N/mm at 1 year to 3534 N/mm at 30 years with a second order polynomial “maturation” relationship. Volumetric bone mineral density and vertebral cross-sectional area together described the developmental patterns of stiffness and yield load of isolated vertebrae. Sex differences were observed throughout development, demonstrating differing growth patterns to accommodate mechanical loading whereby males develop larger size vertebrae and females achieve their mechanical stiffness and strength through greater bone mineral density. [Copyright &y& Elsevier]

The skeleton is the most common site of secondary disease in breast cancer and prostate cancer, with up to 80% of patients with advanced disease developing bone metastases (BM). The proportion is also substantial in advanced lung cancer (20%–40%). Because of the high prevalence of cancers of the breast, prostate and lung, these cancers account for more than 80% of cases of metastatic bone disease occurring in solid tumours. Metastatic bone disease is associated with greatly increased bone resorption by osteoclasts, leading to moderate to severe pain and other skeletal complications, with major impact on quality of life (QoL). Skeletal Related Events (SREs) have been defined as: pathological long bone or vertebral fractures; spinal cord compression; need for radiation for pain relief or to prevent fracture/spinal cord compression, need for surgery to bone and hypercalcaemia. More recently, Symptomatic Skeletal Events (SSEs) have been defined to monitor QoL. Although there are currently no curative treatments for metastatic bone disease, patients with breast or prostate cancer and BM are now surviving for several years and sometimes longer, and prevention of SREs is the key aim to optimization of QoL. Since their discovery 50 years ago and their introduction more than 30 years ago into the field of metastatic bone disease, a range of oral and intravenous bisphosphonate drugs have made a major contribution to prevention of SREs. Large trials have clearly demonstrated the clinical value of different bisphosphonate-based drugs (including the oral drugs ibandronate and clodronate and intravenous agents such as zoledronate and pamidronate), in treatment of hypercalcaemia of malignancy and the reduction of SREs and SSEs in a range of cancers. Despite the success of denosumab in reducing osteolysis, bisphosphonates also remain mainstay drugs for treatment of metastatic bone disease. Recognizing the 50th Anniversary of the discovery of bisphosphonates, this review focuses on their continuing value in BM treatment and their future potential, for example in providing a bone-targeting vehicle for cytotoxic drugs. • Metastasis to the skeleton is a major complication of solid tumours, including breast, prostate, lung and renal cancers. • Bisphosphonates have revolutionized the treatment and clinical outcomes of patients with metastatic bone disease. • Bisphosphonates can prevent/delay onset of skeletal related events (SREs), including hypercalcaemia. • Bisphosphonates improve patient quality of life, including reduction of bone pain. • Current research aims to use the bisphosphonate group to target anti-cancer drugs to bone. [ABSTRACT FROM AUTHOR]

There is evidence that the extent of vertebral bone marrow adiposity increases caudally along the vertebral column in children and adolescents. However, no studies have examined the lipid composition of bone marrow along the vertebral column, which may uniquely influence bone acquisition and metabolism during growth independent of the amount of bone marrow adipose tissue. The goal of this study was to characterize the pattern of lipid composition index measures from the thoracic to lumbar spine (T11-L4) among a sample of adolescents with idiopathic scoliosis (AIS) undergoing routine orthopedic surgical care for scoliosis correction. Adolescents between 14 and 18 years of age, with a confirmed diagnosis of AIS, and undergoing routine posterior spinal fusion surgery at our institution were initially included for this descriptive study. The surgery yielded transpedicular vertebral body marrow samples from T11 through L4; 11 participants had bone marrow samples from T11 through L2 and 4 of the 11 participants had marrow samples from T11 through L4. Lipid composition index measures, including the saturated, monounsaturated, and polyunsaturated index, were measured using a targeted lipidomics technique. Linear regression equation for the slope (m) and Pearson correlation coefficient (r) was computed to assess the pattern of lipid composition index measures along the vertebral column from T11 to L2 (n = 11) and extended analysis to L4. Exploratory analyses were performed to examine the association between the pattern of lipid composition measures (individual slopes) and physical characteristics for T11-L2. For T11-L2, the slope of the saturated index was near 0 (r = 0.08; P = 0.92), whereas the slopes of the unsaturated indices were approximately opposite of one another: the monounsaturated index exhibited a −0.55 change (r = 0.58; P = 0.42) per vertebra and the polyunsaturated index exhibited a 0.52 change (r = 0.72; P = 0.28) per vertebra in the caudal direction from T11-L2. For T11-L4, there were modest changes in slope for the saturated (m = 0.12; r = 0.30; P = 0.57) and monounsaturated (m = −0.68; r = 0.74; P = 0.09) indices, while the polyunsaturated index slope remained similar (m = 0.56; r = 0.89; P = 0.02). Age, sex, height, body mass, and BMI were not associated with the pattern of any of the lipid composition index measures. Study findings in this small sample of individuals with AIS suggest that the bone marrow saturated index may be relatively stable across T11-L4, while the monounsaturated index may decrease by 0.55–0.68% per vertebra and the polyunsaturated index may increase by 0.52–0.56% per vertebra in the caudal direction. • The pediatric pattern of vertebral marrow lipid composition is unknown. • Marrow from 14 to 18 year olds with idiopathic scoliosis from T2-L4 was analyzed. • The saturated index remained relatively stable across T11-L4. • The monounsaturated index decreased by 0.55–0.68% per vertebra caudally. • The polyunsaturated index increased by 0.52–0.56% per vertebra caudally. [ABSTRACT FROM AUTHOR]

The repair of deep osteochondral joint surface defects represents a significant unmet clinical need. Importantly, untreated lesions lead to a high rate of osteoarthritis. The current strategies to repair these defects include osteochondral autograft transplantation or "sandwich" strategies combining bone autografts with autologous chondrocyte implantation, with poorly documented long-term outcomes. In this study, we first investigated the capacity of juvenile osteochondral grafts (OCGs) to repair osteochondral defects in skeletally mature rats. With this regenerative model in view, we produced a new biological, bilayered and scaffold-free Tissue Engineered construct (bTEC) for the repair of a deep osteochondral defect of the rat knee. Cylindrical OCGs were excised from the femoral intercondylar groove of the knee of skeletally immature rats (5 weeks) and transplanted into osteochondral defects created in skeletally mature rats (11 weeks). To create bTECs, micromasses (μMasses) of human periosteum-derived progenitor cells (hPDCs) and human articular chondrocytes (hACs) were produced in vitro using previously optimized chemically defined medium formulations containing growth and differentiation factors including bone morphogenetic proteins. These two μMass types were subsequently implanted as bilayered constructs into osteochondral defects in nude rats. At 4 and 16 weeks after surgery, the knees were collected and processed for subsequent 3D imaging analysis and histological evaluation. Micro-computed tomography (μCT), H&E, and Safranin O staining were used to evaluate the degree and quality of tissue repair. The osteochondral unit of the knee joint in 5 weeks old rats exhibits an immature phenotype, displaying active subchondral bone formation through endochondral ossification and the absence of a tidemark. When transplanted into skeletally mature animals, the immature OCGs resumed their maturation process, i.e. , formed new subchondral bone, established the tidemark, and maintained their Safranin O-positive hyaline cartilage at 16 weeks after transplantation. The bTECs (hPDCs + hACs) could partially recapitulate the biology as seen with the immature OCGs, including the formation of the joint surface architecture with typical zonation, ranging from non-mineralized hyaline cartilage in the superficial layers to a progressively mineralized matrix at the interface with a new subchondral bone plate. Cell-based TE constructs mimicking immature OCGs and displaying a hierarchically organized structure comprising of different tissue forming units seem an attractive strategy to treat deep osteochondral defects of the knee. Unlabelled Image • Immature osteochondral plugs were transplanted into osteochondral knee defects in mature rats. • Immature osteochondral grafts formed a new tidemark, hyaline cartilage, and bone. • Bilayered constructs mimicking the immature osteochondral unit were generated. • Periosteal cell-derived transient cartilage and articular cartilage were used. • Bilayered scaffold-free constructs successfully repaired osteochondral defects. [ABSTRACT FROM AUTHOR]

Low bone mineral status has been reported in patients first presented with adolescent idiopathic scoliosis (AIS). We aimed to study whether low-normal bone mineral density (BMD) is persistent among AIS girls during puberty and at peak bone mass, and whether if such persistence is associated with curve severity and differed from healthy controls. This prospective longitudinal study comprised 550 AIS girls and 194 healthy control subjects followed from 1997 till 2016. Low-normal BMD was defined as z-standardized bone mineral density (z-BMD) of bilateral femoral neck ≤ −1. Markov Chain 2-stages analysis was conducted to investigate the low-normal BMD transition rate. Linear mixed-effects model and Bland-Altman plot were used to investigate whether low-normal BMD is persistent among a subgroup of AIS patients that reached peak bone mass. The average z-BMD were comparable between AIS cohort and controls at 11 years old (−0.532 vs −0.602), but at 19 years old z-BMD worsened among AIS subjects (−0.860) while controls z-BMD improved (−0.455). During growth period until skeletal maturity, persistence of low-normal BMD was high in both cohorts (>80%) and the AIS group with severe curve presented 100% persistence. Subgroup analysis revealed that z-BMD of AIS patients at skeletal maturity and peak bone mass were highly correlated (r2 = 0.905) and with good agreement. AIS patients had poorer BMD that is associated with curve severity and more likely to persist beyond peripubertal period and at peak bone mass when compared to controls. • Low-normal BMD is persistent beyond skeletal maturity in AIS girls. • Compared to healthy control AIS patients are more likely to progress to a low-normal BMD. • Persistence of low-normal BMD is positively associated with curve severity among AIS. • Low bone mineral status remained in AIS patients from maturity to peak bone bass. [ABSTRACT FROM AUTHOR]

• Gut hormone and bone changes were assessed 6 months after gastric bypass surgery. • Peptide YY changes negatively correlated with BMD and bone formation marker changes. • Uncoupling of bone turnover correlated with spine BMD loss. The gut hormones peptide YY (PYY) and ghrelin mediate in part the metabolic benefits of Roux-en-Y gastric bypass (RYGB) surgery. However, preclinical data suggest these hormones also affect the skeleton and could contribute to postoperative bone loss. We investigated whether changes in fasting serum total PYY and ghrelin were associated with bone turnover marker levels and loss of bone mineral density (BMD) after RYGB. Prospective cohort of adults undergoing RYGB (n = 44) at San Francisco academic hospitals. We analyzed 6-month changes in PYY, ghrelin, bone turnover markers, and BMD by dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). We calculated the uncoupling index (UI), reflecting the relative balance of bone resorption and formation. Postoperatively, there was a trend for an increase in PYY (+25 pg/mL, p = 0.07) and a significant increase in ghrelin (+192 pg/mL, p < 0.01). PYY changes negatively correlated with changes in spine BMD by QCT (r=-0.36, p = 0.02) and bone formation marker P1NP (r=-0.30, p = 0.05). Relationships were significant after adjustments for age, sex, and weight loss. No consistent relationships were found between ghrelin and skeletal outcomes. Mean 6-month UI was -3.3; UI correlated with spine BMD loss by QCT (r = 0.40, p = 0.01). Postoperative PYY increases were associated with attenuated increases in P1NP and greater declines in spine BMD by QCT. Uncoupling of bone turnover correlated with BMD loss. These findings suggest a role for PYY in loss of bone mass after RYGB and highlight the relationship between intestinal and skeletal metabolism. [ABSTRACT FROM AUTHOR]