Aging and bone

Comparative profiles of DNA methylation and differential gene expression in osteocytic areas from aged and young mice

Altered DNA methylation upon ageing may result in many age-related diseases such as osteoporosis. However, the changes in DNA methylation that occur in cortical bones, the major osteocytic areas, remain unknown. In our study, we extracted total DNA and RNA from the cortical bones of 6-month-old and 24-month-old mice and systematically analysed the differentially methylated regions (DMRs), differentially methylated promoters (DMPs) and differentially expressed genes (DEGs) between the mouse groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DMR-related genes revealed that they were mainly associated with metabolic signalling pathways, including glycolysis, fatty acid and amino acid metabolism. Other genes with DMRs were related to signalling pathways that regulate the growth and development of cells, including the PI3K-AKT, Ras and Rap1 signalling pathways. The gene expression profiles indicated that the DEGs were mainly involved in metabolic pathways and the PI3K-AKT signalling pathway, and the profiles were verified through real-time quantitative PCR (RT-qPCR). Due to the pivotal roles of the affected genes in maintaining bone homeostasis, we suspect that these changes may be key factors in age-related bone loss, either together or individually. Our study may provide a novel perspective for understanding the osteocyte and its relationship with osteoporosis during ageing. SIGNIFICANCE OF THE STUDY: Our study identified age-related changes in gene expressions in osteocytic areas through whole-genome bisulfite sequencing (WGBS) and RNA-seq, providing new theoretical foundations for the targeted treatment of senile osteoporosis.

Immediate vs conventional loading of Facility-Equator system in mandibular overdenture wearers: 1-year RCT with clinical, biological, and functional evaluation

BACKGROUND

The use of immediate loading (IML) is still poorly explored in elderly patients and implant-retained mandibular overdenture (IMO) wearers. For this reason, more comparisons to conventional loading (CL) are required.

PURPOSE

To evaluate the clinical, biological, functional, and oral health-related quality of life (OHRQOL) influence of CL and IML loading on elders wearing IMO retained by the Facility-Equator system up to 1 year after implant installation.

MATERIAL AND METHODS

Twenty edentulous patients received two narrow diameter implants in the mandible; the loading type (CL or IML) was randomized. The clinical parameters were monitored along with prosthetic events, marginal bone loss (MBL) and bone level change (BLC), implant stability quotients (ISQ), masticatory performance outcomes, and Interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) levels in the peri-implant crevicular fluid during the first year of loading. The OHRQoL was assessed via the Oral Health Impact Profile-EDENT questionnaire. Data were analyzed by the Mann-Whitney, χ² , Wilcoxon paired, and McNemar tests.

RESULTS

After 1 year, MBL, BLC and ISQ were statistically identical (P > .05) in the CL and IML groups. The probing depth at 12 months in the CL group (2.19 mm) was higher than in the IML group (1.29 mm; P ≤ .0001). TNF-α was 33.6% higher in the CL group at 6 months (P = .043), while IL-1β was significantly higher in the IML group up to 6 months. The survival rate was 90% in the CL group and 85% in the IML group; 33 prosthetic events occurred in CL group and 23 in IML group.

CONCLUSIONS

After 12 months, both loading protocols are viable and result in similar clinical, biological, functional, and OHRQOL outcomes. However, IML generates better adaptation of the peri-implant tissues, faster improvement in OHRQoL and fewer prosthetic intercurrences than CL.

Age-related and sex-specific effects on architectural properties and biomechanical response of the C57BL/6N mouse femur, tibia and ulna

Aging is known to reduce bone quality and bone strength. We sought to determine how aging affects the biomechanical and architectural properties of various long bones, and if sex influences age related differences/changes. While researchers have extensively studied these changes in individual bones of mice, there is no comprehensive study of the changes in the bones from the same mice to study the changes with aging. We performed three point bending tests and microcomputed tomography (microCT) analysis on femurs, tibiae and ulnae. Three point bending tests were utilized to calculate biomechanical parameters and imaging was also performed using high resolution microCT to reveal both cortical and trabecular microarchitecture C57BL/6N mice were divided into three age groups: 6, 12 and 22 months. Each age and sex group consisted of 6–7 mice. The ultimate load to failure (UL), elastic stiffness (ES), modulus of elasticity (E) and the moment of inertia about bending axis (MOI) for each bone was calculated using three point bending test. MicroCT scans of all the bones were analyzed to determine cortical bone volume per tissue volume (C.BV/TV), trabecular bone volume per tissue volume (Tb.BV/TV), cortical bone area (B.Ar) using CTAn's microCT analysis and tested for correlation with the biomechanical parameters. Mean (standard error) values of UL in femur decreased from 19.8(0.6) N to 12.8(1.1) N (p < .01) and 17.9(0.6) N to 14.6(1.0) N (p = .02) from 6 to 22 months groups in males and females respectively. Similarly, UL in tibia decreased from 19.8(0.5) N to 14.3(0.2) N (p < .01) and 14.4(0.6) N to 9.5(1.0) N (p < .01) from 6 to 22 months group in males and females respectively. ES in femur decreased from 113.2(7) N/mm to 69.6(6.7) N/mm (p < .01) from 6 to 22 months in males only. ES in tibia decreased from 78.6(3.2) N/mm to 65.0(2.3) N/mm (p = .01) and 53.1(2.9) N/mm to 44.0(1.7) N/mm (p = .02) from 6 to 22 months in males and females respectively. Interestingly, ES in ulna increased from 8.2(0.8) N/mm to 10.9(1.0) N/mm (p = .051) from 6 to 22 months of age in females only. E in femur decreased from 4.0(0.4) GPa to 2.8(0.2) GPa (p = .01) and 6.7(0.5) GPa to 4.5(0.4) GPa (p = .01) from 6 to 22 months of age in males and females respectively while tibia showed no change. However, E in ulna increased from 7.0(0.8) GPa to 11.0(1.1) GPa (p = .01) from 6 to 22 months of age in females only. Changes in age and sex-related bone properties were more pronounced in the femur and tibia, while the ulna showed fewer overall differences. Most of the changes were observed in biomechanical compared to architectural properties and female bones are more severely affected by aging. In conclusion, our data demonstrate that care must be taken to describe bone site and sex-specific, rather than making broad generalizations when describing age-related changes on the biomechanical and architectural properties of the skeleton.

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Assess age/gender related biomechanical property changes in femur, tibiae and ulnae.

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C57Bl/6 mice were divided into three age groups: 6, 12 and 22 months.

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Significant decline in the biomechanical response of femurs and tibiae at the age of 22 months.

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Ulnae showed some improved properties with aging.

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Aging affected biomechanical rather than microCT properties and female bones

Age related changes in the bone microstructure in patients with femoral neck fractures

BACKGROUND

The risk of femoral neck fracture progressively increases with age. However, the reasons behind this consistent increase in the fracture risk can't be completely justified by the decrease in the bone mineral density. The objective of this study was to analyze the correlation between various bone structural features and age.

STUDY DESIGN & METHODS

A total of 29 consecutive patients who suffered an intracapsular hip fracture and underwent joint replacement surgery between May 2012 and March 2013 were included in this study. A 2 cm × 1 cm Ø cylindrical trabecular bone sample was collected from the femoral heads and preserved in formaldehyde. Bone mineral density (BMD), microarchitecture, organic content and crystallography were analyzed using a Dual-energy X-ray absorptiometry scan, micro-CT scan, and high resolution magic-angle-spinning-nuclear magnetic resonance (MAS-NMR), respectively. Statistical correlations were made using Spearman´s or Pearson´s correlation tests depending on the distribution of the continuous variables.

RESULTS

The mean patient age was 79.83 ± 9.31 years. A moderate negative correlation was observed between age and the hydrogen content in bone (¹H), which is an indirect estimate to quantify the organic matrix (r = -0.512, p = 0.005). No correlations were observed between BMD, trabecular number, trabecular thickness, phosphorous content, apatite crystal size, and age (r = 0.06, p = 0.755; r = -0.008, p = 0.967; r = -0.046, p = 0.812; r = -0.152, p = 0.430, respectively). A weak positive correlation was observed between Charlson´s comorbidity index (CCI) and c-axis of the hydroxiapatite (HA) crystals (r = -0.400, p = 0.035).

CONCLUSION

The femoral head relative protein content progressively decreases with age. BMD was not correlated with other structural bone parameters and age. Patients with higher comorbidity scores had larger HA crystals. The present results suggest that the progressive increase in the hip fracture risk in elderly patients could be partially explained by the lower bone protein content in this age group.

Has the Use of Fixation Techniques in THA Changed in This Decade? The Uncemented Paradox Revisited

BACKGROUND

Despite existing studies favoring cemented fixation for patients older than 75 years, a trend toward increased use of uncemented fixation has been described in a 2013 study that used arthroplasty registry data from 2006 to 2010. Updated summarized data are needed beyond 2010 to investigate contemporary trends in the usage of uncemented fixation, especially in patients older than 75 years, and to draw attention to a potential continuing conflict between trends in fixation choice and reported revision risk. Thus, healthcare policy and practice can change and surgeons can make better implant fixation choices.

QUESTIONS/PURPOSES

(1) Has the percentage of primary THAs performed with uncemented fixation changed since 2010? (2) Has the percentage of primary THAs performed in patients older than 75 years performed with uncemented fixation changed since 2010? (3) After stratifying by age, which fixation strategy (cemented versus uncemented and hybrid versus uncemented) is associated with the lowest risk of revision?

METHODS

National annual reports from hip arthroplasty registers were identified, and data were extracted from registers published in English or a Scandinavian language, with at least 3 years of reported data in the period from 2010 to 2017. These included Australia, Denmark, England-Wales, Finland, the Netherlands, New Zealand, Romania, Norway, Sweden, and Switzerland, which are all countries with high completeness rates. Data regarding rates of revisions (all causes) related to fixation methods and secondary to different age groups, were taken directly from the registers and no re-analysis was done. The risk estimates were presented as either hazard ratios, rate per 100 component years or as Kaplan-Meier estimates of revision. The age groups compared for Denmark were younger than 50, 50-59, 60-69,70-79, and older than 80 years, and for Australia, New Zealand, England-Wales, and Finland, they were younger than 55, 55-64, 65-74, and older than 75 years. No data were pooled across the registers.

RESULTS

The current use of uncemented fixation in primary THAs varies between 24% (Sweden) and 71% (Denmark). Increasing use of uncemented fixation has been reported in Norway, Denmark, and Sweden, whereas decreasing use of uncemented fixation has been reported in England-Wales, Australia, New Zealand, and Finland. Examining the group of patients older than 75 years, we found that the use of uncemented fixation has been stable in Netherlands, Sweden, New Zealand, and England-Wales. The use of uncemented fixation is still increasing in Denmark and Australia. In Finland, the use of uncemented fixation has decreased (from 43 % to 24 %) from 2010 to 2017. When compared with uncemented fixation, the risk of revision for hips using cemented fixation was lower in patients older than 75 years for all registers surveyed, except for the oldest males in the Finnish register. In this group, no difference was found between cemented and uncemented fixation.

CONCLUSION

Our findings should be used in healthcare policy as feedback on current THAs being performed so as to direct surgeons to choose the right implant fixation, especially in patients older than 75 years, thereby reducing revision risk and increasing the long-term survival of primary THAs. It appears that femoral stem fixation may be the most important revision risk factor in older patients, and future studies should examine this perspective.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Review on calcium- and magnesium-based silicates for bone tissue engineering applications

Bone is a self-engineered structural component of the human body with multifaceted mechanical strength, which provides indomitable support to the effective functioning of the human body. It is indispensable to find a suitable biomaterial for substituting the bone as the bone substitute material requirement is very high due to the rate of bone fracture and infection lead to osteoporosis in human beings increases rapidly. It is not an easy task to design a material with good apatite deposition ability, a faster rate of dissolution, superior resorbability, high mechanical strength, and significant bactericidal activity. Since the synthetic hydroxyapatite was not able to achieve the dahlite phase of hydroxyapatite (natural bone mineral phase), silicates emerged as an alternate biomaterial to meet the need for bone graft substitutes. All silicates do not exhibit the properties required for bone graft substitutes, as their composition and methodology adopted for the synthesis are different. Calcium, magnesium, and silicon play a major role in the formation of bone mineral and their metabolism during bone formation. In this review, the relationship between composition and activity of calcium, magnesium-based silicates have been discussed along with the future scope of these materials for hard tissue engineering applications.

Numerical modeling of the effects hydration and number of hydrogen bonds on the mechanical properties of the tropocollagen molecule

Bone aging involves structural and molecular modifications, especially at the level of type I tropocollagen. This macromolecule shows two main age-related alterations, which are the decrease of both molecular diameter (due to the loss of hydration) and number of hydrogen bonds. In this work, it is proposed to investigate the influence of these two parameters (molecular diameter and number of hydrogen bonds) on the mechanical behavior of tropocollagen using finite element method. To this end, a novel three-dimensional finite element model of collagen molecule accounting for hydrogen bonds was developed. Then, a numerical design of experiments for the diameter of tropocollagen and variations in the number of hydrogen bonds has been established. The mechanical properties (“load–strain” curve and apparent Young’s modulus) of the collagen molecule were obtained by employing the proposed model to uniaxial tensile tests. The parametric study demonstrates that the mechanical properties of tropocollagen are slightly affected by the rate of hydration but considerably affected by variation of the number of hydrogen bonds. Finally, a fitted analytical function was deduced from the above results showing effects of the two parameters (hydration rate and hydrogen bonds) on the apparent Young’s modulus of tropocollagen. This study could be useful to understand the influence of structural age modifications of tropocollagen on the macroscopic mechanical properties of bone.

Effects of micro-osteoperforations on intraoral miniscrew anchored maxillary molar distalization : A randomized clinical trial

PURPOSE

The aim was to study the effects of micro-osteoperforations (MOPs) on miniscrew-supported maxillary molar distalization.

METHODS

As part of a single center, split-mouth, randomized clinical trial, 20 eligible subjects were randomly recruited from patients who had applied to the orthodontics department of a university dental hospital. In the experimental group, subjects were randomized to receive MOPs to either the left or right maxillary molar region (n = 10). The control group (n = 10) and the contralateral sides of the experimental group (n = 10) did not receive any MOPs. In both groups, distalization of the maxillary molars was performed by miniscrew-supported distalization appliances. Using 3D models, maxillary molar distalization at 3, 6, 9, and 12 weeks was measured. Pain, discomfort, eating difficulty, and speech problem levels were assessed using a visual analog scale (VAS 0-10). Periodontal evaluations were performed.

RESULTS

In all, 18 subjects completed the study. The mean amount of tooth movement was significantly greater on the MOP side compared to contralateral side of the experimental group at all time points. After 12 weeks, the maxillary molars on the MOP side moved 1.17-fold more than those on the contralateral side. No significant differences were found regarding amount of tooth movement between the control group and the MOP and contralateral sides of the experimental group. The rates of tooth movement in the MOP sides of the experimental group, contralateral sides of the experimental group, and the control group were 0.029, 0.025, and 0.028 mm/day, respectively. Pain VAS scores after intervention were significantly increased on the MOP side compared with the contralateral side of the experimental group but not at any other time point. No differences in periodontal scores between the groups were observed.

CONCLUSIONS

A 1.17-fold increase in the rate of tooth movement in the MOP group compared with the contralateral side was recorded. However the accelerating effect of MOPs was lower than expected. The mean pain level was statistically greater in the MOP group compared to the contralateral side only on the first day of application.

Age-related periosteal expansion at femoral neck among elderly women may maintain bending stiffness, but not femoral strength

Periosteal expansion and bone loss have opposite effects on femur strength. Their combined effect has not been fully understood. Our investigation using a recently developed beam model suggested that periosteal expansion may maintain femur bending stiffness among elderly women, but not help preserve femoral strength and reduce hip fracture risk.

INTRODUCTION

Periosteal expansion and bone loss are two accompanying biological phenomena in old population. Their combined effect on bone stiffness, strength, and fracture risk is still not clear, because previous studies have reported contradictory results.

METHODS

A recently developed DXA (dual-energy X-ray absorptiometry)-based beam model was applied to study the effect at the femoral neck. We first made a theoretical analysis. Then, a clinical cohort consisting of 961 women (316 hip fractures and 645 controls, age of 75.9 ± 7.1) was used to investigate the associations quantitatively. We investigated (1) correlations of femoral-neck width and bone mineral density with femoral stiffness and strength; (2) correlations of femoral stiffness, strength, and hip fracture risk index with age; (3) associations of femoral stiffness, strength and fracture risk index with actual fracture status, measured by the area under the curve (AUC) and odds ratio (OR).

RESULTS

The investigation results showed that (i) femoral-neck width had stronger correlation with femoral bending stiffness (r = 0.61-0.82, p < 0.001) than with the other stiffness components, while bone mineral density had stronger correlation with axial/shearing stiffness (r = 0.84-0.97, p < 0.001), strength (r = 0.85-0.92, p < 0.001), and fracture risk index (r = -0.61-0.62, p < 0.001) than with bending stiffness. (ii) The association between femoral bending stiffness and age was insignificant (r = - 0.06-0.05, r > 0.05); The associations of axial/shearing stiffness (r = - 0.27--0.20, p < 0.001), strength (r = - 0.28, p < 0.001), and fracture risk index (r = 0.38, p < 0.001) with age were significant. (iii) Fracture risk index had the strongest association with actual fracture status (AUC = 0.75, OR = 3.19), followed by strength (AUC = 0.74, OR = 2.84) and axial/shearing stiffness (AUC = 0.56-0.65, OR = 2.39-2.49). Femoral bending stiffness had the weakest association (AUC = 0.48-0.69, OR = 1.42-2.09).

CONCLUSION

We concluded that periosteal expansion may be adequate to maintain femoral bending stiffness among elderly women, but it may not help preserve strength and reduce hip fracture risk.

Assessment of Renal Osteodystrophy via Computational Analysis of Label-free Raman Detection of Multiple Biomarkers

Accurate clinical evaluation of renal osteodystrophy (ROD) is currently accomplished using invasive in vivo transiliac bone biopsy, followed by in vitro histomorphometry. In this study, we demonstrate that an alternative method for ROD assessment is through a fast, label-free Raman recording of multiple biomarkers combined with computational analysis for predicting the minimally required number of spectra for sample classification at defined accuracies. Four clinically relevant biomarkers: the mineral-to-matrix ratio, the carbonate-to-matrix ratio, phenylalanine, and calcium contents were experimentally determined and simultaneously considered as input to a linear discriminant analysis (LDA). Additionally, sample evaluation was performed with a linear support vector machine (LSVM) algorithm, with a 300 variable input. The computed probabilities based on a single spectrum were only marginally different (~80% from LDA and ~87% from LSVM), both providing an unacceptable classification power for a correct sample assignment. However, the Type I and Type II assignment errors confirm that a relatively small number of independent spectra (7 spectra for Type I and 5 spectra for Type II) is necessary for a p < 0.05 error probability. This low number of spectra supports the practicality of future in vivo Raman translation for a fast and accurate ROD detection in clinical settings.

Different effects of soybean isoflavone genistein on transforming growth factor levels during orthodontic tooth movement among young and old rabbits

Background: Orthodontic treatment to improve aesthetics and for health reasons is performed in children and adults. Elderly individuals have low levels of estrogen, this results in alveolar bone resorption being greater than alveolar bone apposition. Isoflavones present in soybeans may be able to improve the remodeling process through the induction of osteoblastogenesis by increasing transforming growth factor-β1 (TGF-β1) levels. This study aimed to assess the comparative effect of soybean genistein isoflavone to TGF-β1 during orthodontic tooth movement among juvenile and adult rabbits. Methods: In this study, 12 healthy female rabbits were used. Subjects were divided into four groups (n=3); YG group (young rabbits), YGI group (young rabbits + isoflavones genistein), OG group (old rabbits), and OGI group (old rabbits + isoflavones genistein). Two lower incisors of the rabbit were moved distally using an orthodontic force (50 grams force) delivered by an open coil spring, which was inserted between two brackets. During active movements, the genistein isoflavones were given from the initial installation of the device until days 21, at a dose of 1.2 mg/kg BW once a day. Measurement of TGF-β levels were performed on days 1, 7, 14, 21 after appliance installation. TGF-β1 expression was analyzed using enzyme-linked immunosorbent assay (ELISA) and the optical density (OD) of the sample quantifed using a standard curve. The data obtained were analyzed using one-way Anova followed by Tukey HSD test. Results: The TGF-β1 levels were found to highest in the YGI group, and the TGF-β levels were significantly lower in the OG group ( p<0.05). ELISA analysis also revealed that TGF-β1 levels of the OGI group were significantly higher when compared with the OG group ( p<0.05). Conclusion: The administration of soybean genistein isoflavones could improve TGF-β1 levels in old rabbit's during active orthodontic tooth movement.

Different effects of soybean isoflavone genistein on transforming growth factor levels during orthodontic tooth movement among young and old rabbits

Background: Orthodontic treatment to improve aesthetics and for health reasons is performed in children and adults. Elderly individuals have low levels of estrogen, this results in alveolar bone resorption being greater than alveolar bone apposition. Isoflavones present in soybeans may be able to improve the remodeling process through the induction of osteoblastogenesis by increasing transforming growth factor-β1 (TGF-β1) levels. This study aimed to assess the comparative effect of soybean genistein isoflavone to TGF-β1 during orthodontic tooth movement among juvenile and adult rabbits. Methods: In this study, 12 healthy female rabbits were used. Subjects were divided into four groups (n=3); YG group (young rabbits), YGI group (young rabbits + isoflavones genistein), OG group (old rabbits), and OGI group (old rabbits + isoflavones genistein). Two lower incisors of the rabbit were moved distally using an orthodontic force (50 grams force) delivered by an open coil spring, which was inserted between two brackets. During active movements, the genistein isoflavones were given from the initial installation of the device until days 21, at a dose of 1.2 mg/kg BW once a day. Measurement of TGF-β levels were performed on days 1, 7, 14, 21 after appliance installation. TGF-β1 expression was analyzed using enzyme-linked immunosorbent assay (ELISA) and the optical density (OD) of the sample quantifed using a standard curve. The data obtained were analyzed using one-way Anova followed by Tukey HSD test. Results: The TGF-β1 levels were found to highest in the YGI group, and the TGF-β levels were significantly lower in the OG group ( p<0.05). ELISA analysis also revealed that TGF-β1 levels of the OGI group were significantly higher when compared with the OG group ( p<0.05). Conclusion: The administration of soybean genistein isoflavones could improve TGF-β1 levels in old rabbit's during active orthodontic tooth movement.

Relation between cross-sectional bone geometry and double zonal osteon frequency and morphology

OBJECTIVES

While double-zonal osteons (DZ) are characterized by a hyper-mineralized ring inside their lamellae, recent findings suggest that this ring is also defined by a change in the collagen fibers' orientation. Collagen and minerals are essential components to the maintenance of adequate bone strength and their alteration can modify the mechanical properties of the bone tissue. Consequently, the aim of this study is to explore the effect of past loads, as estimated from cross-sectional geometric properties, on the formation of DZ osteons compared to type I (common) osteons.

MATERIALS AND METHODS

The sample consists of paired humerus and femur midshaft sections (n = 23) of Eurocanadian settlers from the historical St. Matthew cemetery, Quebec City (1771-1860). Histomorphometric variables included in this study are osteon density for DZ and type I osteons (DZD; OPD), osteon area (DZOn.Ar; On. Ar), Haversian canal area (DZH.Ar; H.Ar), and the area within the hypermineralized ring (HR. Ar). Loading history is estimated from cross-sectional properties including the following variable: cortical and total area (CA, TA), maximum and minimum second moment of area (I_max , I_min ) and polar moment of area (J).

RESULTS

When the humerus and femur of the same individuals are compared, the femur has a higher OPD, DZD, and relative DZD (DZD/OPD). DZ osteons have a smaller area and Haversian canal area compared to type I osteons. The area within the hypermineralized ring in DZ is higher than the Haversian canal area of the type I osteons. Correlations between the residual scores of the regression of histomorphometric variables and cross-sectional properties of the humerus on the femur were not significant.

DISCUSSION

Based on the analysis of the entire cross-section, the lack of correlation between variations in cross-sectional properties and remodeling combined with the significant differences between humeri and femura suggests that the creation of DZ or type I osteons in the bone tissue might be due to a bone specific response, possibly related to differences in bone tissue age that needs to be further investigated. Definitive conclusion regarding biomechanical loads still seem to be premature as regional variations associated with mechanical properties remain to be explored.

Functional disuse initiates medullary endosteal micro-architectural impairment in cortical bone characterized by nanoindentation

In this study, we evaluated the effect of functional disuse-induced bone remodeling on its mechanical properties, individually at periosteum and medullary endosteum regions of the cortical bone. Left middle tibiae were obtained from 5-month-old female Sprague-Dawley rats for the baseline control as well as hindlimb suspended (disuse) groups. Micro-nano-mechanical elastic moduli (at lateral region) was evaluated along axial (Z), circumferential (C) and radial (R) orientations using nanoindentation. Results indicated an anisotropic microstructure with axial orientation having the highest and radial orientation with the lowest moduli at periosteum and medullary endosteum for both baseline control as well as disuse groups. Between the groups: at periosteum, an insignificant difference was evaluated for each of the orientations (p > 0.05) and at endosteum, a significant decrease of elastic moduli in the radial (p < 0.0001), circumferential (p < 0.001) and statistically insignificant difference in axial (p > 0.05) orientation. For the moduli ratios between groups: at periosteum, only significant difference in the Z/R (p < 0.05) anisotropy ratio, whereas at endosteum, a statistically significant difference in Z/C (p < 0.001), and Z/R (p < 0.001), as well as C/R (p < 0.05) anisotropy ratios, was evaluated. The results suggested initial bone remodeling impaired bone micro-architecture predominantly at the medullary endosteum with possible alterations in the geometric orientations of collagen and mineral phases inside the bone. The findings could be significant for studying the mechanotransduction pathways involved in maintaining the bone micro-architecture and possibly have high clinical significance for drug use against impairment from functional disuse.

Cementless versus Cemented Fixation in Total Knee Arthroplasty: Usage, Costs, and Complications during the Inpatient Period

Cemented fixation has been the gold standard in total knee arthroplasty (TKA). However, with younger and more active patients requiring TKA, cementless (press-fit) fixation has sparked renewed interest. Therefore, we investigated differences in (1) patient demographics, (2) inpatient costs, (3) short-term complications, and (4) discharge disposition between patients who underwent TKA with cemented and cementless fixation. The National Inpatient Sample database was queried for TKA patients with cement or cementless fixation between October 1 and December 31, 2015. Primary outcomes of interest included complications, length of stay (LOS), discharge disposition, and inpatient costs. Student's t-test and chi-square analysis were used to assess continuous and categorical data, respectively. Multivariable analysis evaluated the effects of fixation type on the continuous and categorical dependent variables. Patients who received cementless fixation were more often younger (63.5 vs. 65.9 years), male (47.4 vs. 40.3%), Black (10.7 vs. 7.7%), from the Northeast census region (29.1 vs. 17.1%), and under private insurance (49.2 vs. 40.3%; p < 0.001 for all). Cementless fixation involved higher inpatient hospital costs (US$17,357 vs. US$16,888) and charges (US$67,366 vs. US$64,190; p < 0.001 for both), lower mean LOS (2.63 vs. 2.71 days; p < 0.001), and higher odds of being discharged to home (odds ratio = 1.99; p = 0.002). This study revisited the outcomes of TKA with cementless fixation and demonstrated higher inpatient charges and costs, shorter mean LOS, and higher odds of being discharged home. Future studies should investigate patient outcomes and complications past the inpatient period, evaluate long-term survivorship and failure rates, and implement a prospective study design.

HU-671, a Novel Oleoyl Serine Derivative, Exhibits Enhanced Efficacy in Reversing Ovariectomy-Induced Osteoporosis and Bone Marrow Adiposity

Oleoyl serine (OS), an endogenous fatty acyl amide (FAA) found in bone, has been shown to have an anti-osteoporotic effect. OS, being an amide, can be hydrolyzed in the body by amidases. Hindering its amide bond by introducing adjacent substituents has been demonstrated as a successful method for prolonging its skeletal activity. Here, we tested the therapeutic efficacy of two methylated OS derivatives, oleoyl α-methyl serine (HU-671) and 2-methyl-oleoyl serine (HU-681), in an ovariectomized mouse model for osteoporosis by utilizing combined micro-computed tomography, histomorphometry, and cell culture analyses. Our findings indicate that daily treatment for 6 weeks with OS or HU-671 completely rescues bone loss, whereas HU-681 has only a partial effect. The increased bone density was primarily due to enhanced trabecular thickness and number. Moreover, the most effective dose of HU-671 was 0.5 mg/kg/day, an order of magnitude lower than with OS. The reversal of bone loss resulted from increased bone formation and decreased bone resorption, as well as reversal of bone marrow adiposity. These results were further confirmed by determining the serum levels of osteocalcin and type 1 collagen C-terminal crosslinks, as well as demonstrating the enhanced antiadipogenic effect of HU-671. Taken together, these data suggest that methylation interferes with OS’s metabolism, thus enhancing its effects by extending its availability to its target cells.

Human Oral Stem Cells, Biomaterials and Extracellular Vesicles: A Promising Tool in Bone Tissue Repair

Tissue engineering and/or regenerative medicine are fields of life science exploiting both engineering and biological fundamentals to originate new tissues and organs and to induce the regeneration of damaged or diseased tissues and organs. In particular, de novo bone tissue regeneration requires a mechanically competent osteo-conductive/inductive 3D biomaterial scaffold that guarantees the cell adhesion, proliferation, angiogenesis and differentiation into osteogenic lineage. Cellular components represent a key factor in tissue engineering and bone growth strategies take advantage from employment of mesenchymal stem cells (MSCs), an ideal cell source for tissue repair. Recently, the application of extracellular vesicles (EVs), isolated from stem cells, as cell-free therapy has emerged as a promising therapeutic strategy. This review aims at summarizing the recent and representative research on the bone tissue engineering field using a 3D scaffold enriched with human oral stem cells and their derivatives, EVs, as a promising therapeutic potential in the reconstructing of bone tissue defects.

Chronic kidney disease and aging differentially diminish bone material and microarchitecture in C57Bl/6 mice

Chronic kidney disease (CKD) is a common disease of aging and increases fracture risk over advanced age alone. Aging and CKD differently impair bone turnover and mineralization. We thus hypothesize that the loss of bone quality would be greatest with the combination of advanced age and CKD. We evaluated bone from young adult (6 mo.), middle-age (18 mo.), and old (24 mo.) male C57Bl/6 mice three months following either 5/6th nephrectomy, to induce CKD, or Sham procedures. CKD exacerbated losses of cortical and trabecular microarchitecture associated with aging. Aging and CKD each resulted in thinner, more porous cortices and fewer and thinner trabeculae. Bone material quality was also reduced with CKD, and these changes to bone material were distinct from those due to age. Aging reduced whole-bone flexural strength and modulus, micrometer-scale nanoindentation modulus, and nanometer-scale tissue and collagen strain (small-angle x-ray scattering [SAXS]. By contrast, CKD reduced work to fracture and variation in bone tissue modulus and composition (Raman spectroscopy), and increased percent collagen strain. The increased collagen strain burden was associated with loss of toughness in CKD. In addition, osteocyte lacunae became smaller, sparser, and more disordered with age for Sham mice, yet these age-related changes were not clearly observed in CKD. However, for CKD, larger lacunae positively correlated with increased serum phosphate levels, suggesting that osteocytes play a role in systemic mineral homeostasis. This work demonstrates that CKD reduces bone quality, including microarchitecture and bone material properties, and that loss of bone quality with age is compounded by CKD. These findings may help reconcile why bone mass does not consistently predict fracture in the CKD population, as well as why older individuals with CKD are at high risk of fragility.

Accelerated discovery and mechanical property characterization of bioresorbable amorphous alloys in the Mg-Zn-Ca and the Fe-Mg-Zn systems using high-throughput methods

Ternary amorphous alloys in the magnesium (Mg)-zinc (Zn)-calcium (Ca) and the iron (Fe)-Mg-Zn systems are promising candidates for use in bioresorbable implants and devices. The optimal alloy compositions for biomedical applications should be chosen from a large variety of available alloys with best combination of mechanical properties (modulus, strength, hardness) and biological response (in situ degradation rates, cell adhesion and proliferation). As a first step towards establishing a database designed to enable such targeted material selection, amorphous alloy composition libraries were fabricated employing a combinatorial magnetron sputtering approach where Mg, Zn, and Ca/Fe are co-deposited from separate sources onto a silicon wafer substrate. Composition analysis using energy dispersive X-ray spectroscopy documented a composition range of ∼15-85 at% Mg, ∼6-55 at% Zn, and ∼5-60 at% Ca for the Mg-Zn-Ca library and ∼26-84 at% Mg, ∼10-61 at% Zn, and ∼7-55 at% Fe for the Fe-Mg-Zn library. X-ray diffraction measurements established that amorphous alloys (i.e., glasses) form in almost the entire range of composition at the high cooling rates during sputtering for both alloy libraries. Finally, the effective material modulus, the Oliver-Pharr hardness, and the yield strength values obtained using nanoindentation reveal a wide range of mechanical properties within both systems.

Exercise or manual physiotherapy compared with a single session of physiotherapy for osteoporotic vertebral fracture: three-arm PROVE RCT

BACKGROUND

A total of 25,000 people in the UK have osteoporotic vertebral fracture (OVF). Evidence suggests that physiotherapy may have an important treatment role.

OBJECTIVE

The objective was to investigate the clinical effectiveness and cost-effectiveness of two different physiotherapy programmes for people with OVF compared with a single physiotherapy session.

DESIGN

This was a prospective, adaptive, multicentre, assessor-blinded randomised controlled trial (RCT) with nested qualitative and health economic studies.

SETTING

This trial was based in 21 NHS physiotherapy departments.

PARTICIPANTS

The participants were people with symptomatic OVF.

INTERVENTIONS

Seven sessions of either manual outpatient physiotherapy or exercise outpatient physiotherapy compared with the best practice of a 1-hour single session of physiotherapy (SSPT).

MAIN OUTCOME MEASURES

Outcomes were measured at 4 and 12 months. The primary outcomes were quality of life and muscle endurance, which were measured by the disease-specific QUALEFFO-41 (Quality of Life Questionnaire of the European Foundation for Osteoporosis - 41 items) and timed loaded standing (TLS) test, respectively. Secondary outcomes were (1) thoracic kyphosis angle, (2) balance, evaluated via the functional reach test (FRT), and (3) physical function, assessed via the Short Physical Performance Battery (SPPB), 6-minute walk test (6MWT), Physical Activity Scale for the Elderly, a health resource use and falls diary, and the EuroQol-5 Dimensions, five-level version.

RESULTS

A total of 615 participants were enrolled, with 216, 203 and 196 randomised by a computer-generated program to exercise therapy, manual therapy and a SSPT, respectively. Baseline data were available for 613 participants, 531 (86.6%) of whom were women; the mean age of these participants was 72.14 years (standard deviation 9.09 years). Primary outcome data were obtained for 69% of participants (429/615) at 12 months: 175 in the exercise therapy arm, 181 in the manual therapy arm and 173 in the SSPT arm. Interim analysis met the criteria for all arms to remain in the study. For the primary outcomes at 12 months, there were no significant benefits over SSPT of exercise [QUALEFFO-41, difference -0.23 points, 95% confidence interval (CI) -3.20 to 1.59 points; p = 1.000; and TLS test, difference 5.77 seconds, 95% CI -4.85 to 20.46 seconds; p = 0.437] or of manual therapy (QUALEFFO-41, difference 1.35 points, 95% CI -1.76 to 2.93 points; p = 0.744; TLS test, difference 9.69 seconds (95% CI 0.09 to 24.86 seconds; p = 0.335). At 4 months, there were significant gains for both manual therapy and exercise therapy over SSPT in the TLS test in participants aged < 70 years. Exercise therapy was superior to a SSPT at 4 months in the SPPB, FRT and 6MWT and manual therapy was superior to a SSPT at 4 months in the TLS test and FRT. Neither manual therapy nor exercise therapy was cost-effective relative to a SSPT using the threshold of £20,000 per quality-adjusted life-year. There were no treatment-related serious adverse events.

CONCLUSIONS

This is the largest RCT to date assessing physiotherapy in participants with OVFs. At 1 year, neither treatment intervention conferred more benefit than a single 1-hour physiotherapy advice session. The focus of future work should be on the intensity and duration of interventions to determine if changes to these would demonstrate more sustained effects.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN49117867.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 44. See the NIHR Journals Library website for further project information.

Can children be affected by bisphosphonate-related osteonecrosis of the jaw? A systematic review

Knowledge of bisphosphonate-related osteonecrosis of the jaw (BRONJ) is mostly based on adult cases, however bisphosphonates are also currently recommended for different paediatric diseases resulting in osteoporosis. The aim of this study was to review the literature on the risk of developing BRONJ in children and adolescents. The PubMed, LILACS, Web of Science, Scopus, and Cochrane databases were searched using the key words "bisphosphonates", "osteonecrosis", "jaw", and "children". Literature reviews, case reports, abstracts, theses, textbooks, and book chapters were excluded. Studies involving children and young adults (younger than 24 years of age) were included. A total of 56 publications were identified. After applying the eligibility criteria, only seven articles remained. Although no cases of osteonecrosis were identified, all studies had weaknesses such as a limited sample size or the absence of risk factors for the development of osteonecrosis. There is general consensus that this subject should be of concern and that further studies should be conducted before any definitive opinion is reached. It is believed that patients with secondary osteoporosis who use bisphosphonates continuously should be followed up during adulthood, since bone turnover decreases over the years.

Injectable Tissue Replacement and Regeneration: Anatomic Fat Grafting to Restore Decayed Facial Tissues

Aging is a dynamic process that can be modeled and understood tissue by tissue and cell by cell. Numerous authors have helped us understand the anatomy of facial fat compartments and the effects of aging on our facial tissues such as skin, fat, bone and fibrous ligaments. Injectable tissue replacement and regeneration (ITR2) is a method to replace decayed tissues of the face using “like tissues” in an effort to delay or slow the rate of tissue decay seen in facial aging. Facial topography and proportion analysis are performed to diagnose individual-specific losses of facial fat. The degree of sun damage and skin thinning is noted as is the degree of loss in the superficial fat compartment. Deep compartment fat loss is evaluated as is pyriform aperture, orbital, mandibular ramus, mandibular body, and chin resorption. From this analysis, a detailed treatment plan is formulated. Using a mechanical device, 3 different fat grafts are created: 2 mm (millifat), 1 mm (microfat), and 500 microns (cell optimized, matrix rich nanofat); anatomic replacement of all areas of tissue loss is carried out. Millifat is used for deep compartment and bone losses, microfat for superficial fat losses above the facial musculature and nanofat is used intradermally and as a biological cream for topical application. The rationale behind this standardized approach is explained and the scientific foundations for the idea are presented. Reduction in tissue decay appears to be a valid observation, but awaits others confirmation.

Allometry and advancing age significantly structure craniofacial variation in adult female baboons

Primate craniofacial growth is traditionally assumed to cease upon maturation or at least be negligible, whereas bony remodeling is typically associated with advanced adult age and, in particular, tooth loss. Therefore, size and shape of the craniofacial skeleton of young and middle-aged adults should be stable. However, research on both modern and historic human samples suggests that portions of the CFS exhibit age-related changes in mature individuals, both related to and independent of tooth loss. These results demonstrate that the age-category 'adult' is heterogeneous, containing individuals demonstrating post-maturational age-related variation, but the topic remains understudied outside of humans and in the cranial vault and base. Our research quantifies variation in a sample of captive adult female baboons (n = 97) in an effort to understand how advancing age alters the mature CFS. Craniometric landmarks and sliding semilandmarks were collected from computed tomography (CT) scans of adult baboons aged 7-32 years old. To determine whether craniofacial morphology is sensitive to aging mechanisms and whether any such effects are differentially distributed throughout the cranium, geometric morphometric techniques were employed to compare the shapes of various cranial regions among individuals of increasing age. Unexpectedly, the biggest form differences were observed between young and middle-aged adults, rather than between adults with full dentitions and those with some degree of tooth loss. Shape variation was greatest in masticatory and nuchal musculature attachment areas. Our results indicate that the craniofacial skeleton changes form during adulthood in baboons, raising interesting questions about the molecular and biological mechanisms governing these changes.

Mechanical Competence and Bone Quality Develop During Skeletal Growth

Bone fracture risk is influenced by bone quality, which encompasses bone's composition as well as its multiscale organization and architecture. Aging and disease deteriorate bone quality, leading to reduced mechanical properties and higher fracture incidence. Largely unexplored is how bone quality and mechanical competence progress during longitudinal bone growth. Human femoral cortical bone was acquired from fetal (n = 1), infantile (n = 3), and 2- to 14-year-old cases (n = 4) at the mid-diaphysis. Bone quality was assessed in terms of bone structure, osteocyte characteristics, mineralization, and collagen orientation. The mechanical properties were investigated by measuring tensile deformation at multiple length scales via synchrotron X-ray diffraction. We find dramatic differences in mechanical resistance with age. Specifically, cortical bone in 2- to 14-year-old cases exhibits a 160% greater stiffness and 83% higher strength than fetal/infantile cases. The higher mechanical resistance of the 2- to 14-year-old cases is associated with advantageous bone quality, specifically higher bone volume fraction, better micronscale organization (woven versus lamellar), and higher mean mineralization compared with fetal/infantile cases. Our study reveals that bone quality is superior after remodeling/modeling processes convert the primary woven bone structure to lamellar bone. In this cohort of female children, the microstructural differences at the femoral diaphysis were apparent between the 1- to 2-year-old cases. Indeed, the lamellar bone in 2- to 14-year-old cases had a superior structural organization (collagen and osteocyte characteristics) and composition for resisting deformation and fracture than fetal/infantile bone. Mechanistically, the changes in bone quality during longitudinal bone growth lead to higher fracture resistance because collagen fibrils are better aligned to resist tensile forces, while elevated mean mineralization reinforces the collagen scaffold. Thus, our results reveal inherent weaknesses of the fetal/infantile skeleton signifying its inferior bone quality. These results have implications for pediatric fracture risk, as bone produced at ossification centers during children's longitudinal bone growth could display similarly weak points. © 2019 American Society for Bone and Mineral Research.

Osteocyte numbers decrease only in postcranial but not in cranial bones in humans of advanced age

BACKGROUND

Bone ageing is governed by the linked activities of short-lived osteoblasts and osteoclasts in conjunction with long-lived osteocytes present in osseous structure. Besides their maintenance function, osteogenic cells also gain specific positional information, which may potentially trigger ageing-associated cellular deviations in terminally differentiated osteocytes differently in cranial versus postcranial tissues.

METHODS

We therefore investigated bone taken from deceased aged humans explanted at five distinct anatomical positions throughout the body and assessed physical and biological determinants applying radiologic and histologic measures.

RESULTS

We were able to show that significantly more osteocytes reside in aged cortical bone at cranial positions than within axial or limb skeleton. These cellular states and conditions were not found in the corresponding trabecular bone, where osteocyte numbers remain also high at postcranial positions. Parallel comparative analyses of bone microstructure as analyzed by means of computer tomography showed no significant differences.

CONCLUSIONS

Considering differences and commonalities regarding the bone samples, such as loading, mechanisms of ossification or the surrounding stromal cell compartment, our findings indicate that positional information laid down during ontogenetic processes is instructive during the entire life thus potentially also moulding spatial-specific mechanistic distinctions of bone ageing.

Mapping of inflammatory biomarkers in the peri-implant crevicular fluid before and after the occlusal loading of narrow diameter implants

OBJECTIVE

To monitor the cytokine release patterns in the peri-implant crevicular fluid (PICF) and to investigate which factors affect the success rate of narrow diameter implants (NDI) during the first year.

MATERIAL AND METHODS

Mandibular implant overdentures (IOD) retained by 2 NDI were installed in 16 clinically atrophic edentulous patients. The following parameters were monitored during the first year: (i) peri-implant health parameters (plaque index (PI), calculus presence (CP), gingival index (GI), probing depth (PD) and bleeding on probing (BoP); (ii) cytokine concentrations in the PICF (TNF-α, IL-1β, IL-6, IL-10); (iii) implant stability quotient (ISQ); (iv) marginal bone level (MBL) and bone level change (BLC); (v) implant success. The insertion torque, bone type, mandibular atrophy, time since edentulism, and smoking habits were also recorded. All data were analyzed using multivariable multilevel mixed-effects regression models.

RESULTS

The variability in the TNF-α release patterns temporarily reduced at weeks (w) 8-12, while the IL-1β concentrations remained low until they peaked at w48 [p < 0.05; + 177.55 pg/μl (+ 96.13 - + 258.97)]. Conversely, IL-10 release decreased significantly at w48 [p < 0.05; - 456.24 pg/μl (- 644.41 - - 268.07)]. The PD and ISQ decreased significantly (p < 0.05) over the follow-up period, while the MBL was stable after w48 with a BLC of 0.12 ± 0.71 mm. The overall success rate was 81.3%, and was influenced by TNF-α, IL-1β, IL-10, PI, GI, PD, smoking, and time since edentulism.

CONCLUSION

Pro- and anti-inflammatory cytokine release was balanced during the first 24 weeks. The GI, smoking, and time since edentulism are the most important factors determining the implant success.

CLINICAL RELEVANCE

The study contributes to the understanding of the osseointegration process in a clinically atrophic population rehabilitated with IOD, and highlights the importance of monitoring clinical peri-implant health-related parameters, smoking habit, and time since edentulism to predict implant success rates.

Environmentally-Controlled Near Infrared Spectroscopic Imaging of Bone Water

We have designed an environmentally-controlled chamber for near infrared spectroscopic imaging (NIRSI) to monitor changes in cortical bone water content, an emerging biomarker related to bone quality assessment. The chamber is required to ensure repeatable spectroscopic measurements of tissues without the influence of atmospheric moisture. A calibration curve to predict gravimetric water content from human cadaveric cortical bone was created using NIRSI data obtained at six different lyophilization time points. Partial least squares (PLS) models successfully predicted bone water content that ranged from 0–10% (R = 0.96, p < 0.05, root mean square error of prediction (RMSEP) = 7.39%), as well as in the physiologic range of 4–10% of wet tissue weight (R = 0.87, p < 0.05, RMSEP = 14.5%). Similar results were obtained with univariate and bivariate regression models for prediction of water in the 0–10% range. Further, we identified two new NIR bone absorbances, at 6560 cm⁻¹ and 6688 cm⁻¹, associated with water and collagen respectively. Such data will be useful in pre-clinical studies that investigate changes in bone quality with disease, aging and with therapeutic use.

High-resolution large-area imaging of nanoscale structure and mineralization of a sclerosing osteosarcoma in human bone

Osteosarcoma is the most common primary bone cancer type in humans. It is predominantly found in young individuals, with a second peak later in life. The tumour is formed by malignant osteoblasts and consists of collagenous, sometimes also mineralized, bone matrix. While the morphology of osteosarcoma has been well studied, there is virtually no information about the nanostructure of the tumour and changes in mineralization on the nanoscale level. In the present paper, human bone tissue inside, next to and remote from a sclerosing osteosarcoma was studied with small angle x-ray scattering, x-ray diffraction and electron microscopy. Quantitative evaluation of nanostructure parameters was combined with high resolution, large area mapping to obtain microscopic images with nanostructure parameter contrast. It was found that the tumour regions were characterized by a notable reduction in mineral particle size, while the mineral content was even higher than that in normal bone. Furthermore, the normal preferential orientation of mineral particles along the longitudinal direction of corticalis or trabeculae was largely suppressed. Also the bone mineral crystal structure was affected: severe crystal lattice distortions were detected in mineralized tumour tissue pointing to a different ion substitution of hydroxyl apatite in tumorous tissue than in healthy tissue.

Bisphosphonates and Cancer: A Relationship Beyond the Antiresorptive Effects

Bisphosphonates (BPs) are stable analogues of the Inorganic Pyrophosphate (PPi), an endogenous regulator of bone mineralization, which can resist the hydrolysis in the gastrointestinal tract. Their conformation allows targeting the bone as a result of their three-dimensional structure, which makes them primary agents against osteoclast-mediated bone loss. They are used in many bone pathological conditions, like bone metastasis, because of its ability to modulate bone metabolism into a less favorable place to cancer cell growth, through the inhibition of osteoclastogenesis and bone resorption. This review is focused on the mechanisms of action through which BPs affect the cellular activity and survival, mainly on their antitumoral effects. In conclusion, BPs are considered the primary therapy for skeletal disorders due to its high affinity for bone, but now they are also considered as potential antitumor agents due to its ability to induce tumor cell apoptosis, inhibition of cell adhesion, invasion and proliferation, modulation of the immune system to target and eliminate cancer cells as well as affect the angiogenic mechanisms. Like any other drug, they also have some adverse effects, but the most common, the acute phase reaction, can be minimized with the intake of calcium and vitamin D.

Peri-implant marginal bone loss rate pre- and post-loading: An exploratory analysis of associated factors

OBJECTIVES

To perform an exploratory analysis of factors influencing annual rates of peri-implant marginal bone loss (RBL) calculated over different time frames, at implants unaffected by peri-implantitis.

MATERIAL AND METHODS

A total of 154 implants from 86 patients were reviewed at 1.6-6.8 years after placement. Marginal bone levels (MBL) were assessed on intraoral radiographs at three time-points: immediately post-placement, time of loading, and least 1-year post-loading. RBLs (mm/year) were computed using these three time frames and corresponding MBL changes as: RBL placement-loading, RBL loading-review, RBL placement-review. Exploratory ordination of three RBLs, corresponding time durations, and 17 background factors were used for visualization. Hierarchical linear mixed-effects models (MEM) with predictor selection were applied to RBL outcomes. The correlation of actual MBL with MBLs predicted by RBL placement-loading and RBL loading-review was tested.

RESULTS

Median RBL placement-loading was 0.9 mm/year (IQR = 2.02), loading-review was 0.06 mm/year (IQR = 0.16), and overall RBL placement-review was 0.21 mm/year (IQR = 0.33). Among-patient variance was highest for RBL placement-loading (SD = 0.66). Longer time predicted lower RBL in all time frames. Shorter time of loading significantly predicted lower RBL placement-review. Augmentation predicted lower RBL placement-loading, while anterior location and older age predicted lower RBLs placement-loading placement-review. Only MBL projected using RBL placement-loading significantly correlated with actual MBL.

CONCLUSIONS

Exploratory analysis indicated RBL varied with the time duration used for calculation in pre- and post-loading, and overall periods. In each period, RBL declined with increasing time. Earlier loading predicted lower overall RBL. Higher pre-loading RBL predicted worse actual bone level.

Hypermineralization in the femoral neck of the elderly

Hip fragility depends on the decline in bone mass as well as changes in bone microstructure and the properties of bone mineral and organic matrix. Although it is well-established that low bone mass or osteoporosis is a key factor in hip fracture risk, it is striking to observe that 92% of 24 patients who have sustained an intracapsular hip fracture showed hypermineralization at the superior-anterior quadrant, a critical region associated with increased hip fracture risk. In-depth material studies on a total of 12 human cadaver femurs revealed increased degree of mineralization in the hypermineralized tissue: calcium weight percentage as measured by quantitative backscattered electron imaging increased by approximately 15% compared with lamellar bone; mineral-to-matrix ratio obtained by Raman microspectroscopy imaging also increased. Immunohistochemistry revealed localized type II collagen in the hypermineralized region, implying its cartilaginous nature. At the ultrastructural level, X-ray scattering revealed significantly smaller (on average 2.3 nm thick and 15.6 nm long) and less ordered bone minerals in the hypermineralized tissue. Finally, the hypermineralized tissue was more brittle than lamellar bone under hydrated state - cracks propagated easily in the hypermineralized region but stopped at the lamellar boundary. This study demonstrates that hypermineralization of femoral neck cortical bone is a source of bone fragility which is worth considering in future fracture risk assessment when the origin of hip fracture is unclear based on current evaluation standards. STATEMENT OF SIGNIFICANCE: Hypermineralization of femoral cortical bone in older adults might occur in many more hip fracture cases than presently known. Yet, this tissue remains largely unknown to the orthopedic community possibly due to coarse resolution of clinical imaging. The current study showed the hypermineralized tissue had reduced fracture resistance which could be attributed to the material changes in mineral content, organic matrix, and mineral platelets properties. It thus could be a source for fracture initiation. Consequently, we believe hypermineralization of femoral neck cortical bone should be considered in hip fragility assessment, especially when low bone mass cannot be identified as a primary contributor to hip fracture.

Alveolar bone plate measurements of maxillary anterior teeth: A retrospective Cone Beam Computed Tomography study, AlMadianh, Saudi Arabia

Purpose

To study bone profile (facial bone thickness and height of alveolar bone crest) of anterior maxillary teeth in the aesthetic area among Saudi dentulous adults.

Methods

This retrospective study was conducted at Taibah University College of Dentistry and Hospital, AlMadinah; Saudi Arabia. The analysis included 490 adult patients' Cone Beam Computed Tomography (CBCT) retrieved from Kodak Carestream-R4 database. Alveolar bone thicknesses and crest bone-height for maxillary anterior teeth were measured directly on CBCT images using built-in digital caliper. Descriptive statistics and comparative analysis were performed.

Results

Of the 490 CBCTs 186 were found useable for the study purpose. The mean age of the patients was 34.65 ± 11.57and 109 (59%) were males. Statistically significant (P < 0.001) differences were found between the mean ± SD facial plate thickness of the central incisors, lateral incisors, and canines (1.12 ± 0.28 mm, 1.14 ± 0.31 mm, and 1.03 ± 0.24 mm, respectively). In addition, facial plate height increased statistically significantly positively with age for the central incisors, lateral incisors, and canines (r = 0.543, n = 186, p = 0.001; r = 0.515, n = 186, p = 0.001; r = 0.474, n = 186, p = 0.001, respectively). Genderwise, males had statistically significantly (P < 0.00) higher facial bone thickness e.g. in central incisor (males 1.20 ± 0.29 VS females 1.04 ± 0.25, p = 0.001) and increased bone height (Males 2.62 ± 0.77VS females 2.09 ± 0.66, p = 0.001) compared to females.

Conclusion

In this study, the significant differences in bone thickness and crest height between anterior maxillary teeth in the aesthetic area was highlighted. Notably, increases in facial plate crest height was linked to age and male and female differed on both facial bone thickness and bone height.

Tissue engineered bone mimetics to study bone disorders ex vivo: Role of bioinspired materials

Recent advances in materials development and tissue engineering has resulted in a substantial number of bioinspired materials that recapitulate cardinal features of bone extracellular matrix (ECM) such as dynamic inorganic and organic environment(s), hierarchical organization, and topographical features. Bone mimicking materials, as defined by its self-explanatory term, are developed based on the current understandings of the natural bone ECM during development, remodeling, and fracture repair. Compared to conventional plastic cultures, biomaterials that resemble some aspects of the native environment could elicit a more natural molecular and cellular response relevant to the bone tissue. Although current bioinspired materials are mainly developed to assist tissue repair or engineer bone tissues, such materials could nevertheless be applied to model various skeletal diseases in vitro. This review summarizes the use of bioinspired materials for bone tissue engineering, and their potential to model diseases of bone development and remodeling ex vivo. We largely focus on biomaterials, designed to re-create different aspects of the chemical and physical cues of native bone ECM. Employing these bone-inspired materials and tissue engineered bone surrogates to study bone diseases has tremendous potential and will provide a closer portrayal of disease progression and maintenance, both at the cellular and tissue level. We also briefly touch upon the application of patient-derived stem cells and introduce emerging technologies such as organ-on-chip in disease modeling. Faithful recapitulation of disease pathologies will not only offer novel insights into diseases, but also lead to enabling technologies for drug discovery and new approaches for cell-based therapies.

The role of subchondral bone, and its histomorphology, on the dynamic viscoelasticity of cartilage, bone and osteochondral cores

OBJECTIVE

Viscoelastic properties of articular cartilage have been characterised at physiological frequencies. However, studies investigating the interaction between cartilage and subchondral bone and the influence of underlying bone histomorphometry on the viscoelasticity of cartilage are lacking.

METHOD

Dynamic Mechanical Analysis (DMA) has been used to quantify the dynamic viscoelasticity of bovine tibial plateau osteochondral cores, over a frequency sweep from 1 to 88 Hz. Specimens (approximately aged between 18 and 30 months) were neither osteoarthritic nor otherwise compromised. A maximum nominal stress of 1.7 MPa was induced. Viscoelastic properties of cores have been compared with that of its components (cartilage and bone) in terms of the elastic and viscous components of both structural stiffness and material modulus. Micro-computed tomography scans were used to quantify the histomorphological properties of the subchondral bone.

RESULTS

Opposing frequency-dependent loss stiffness, and modulus, trends were witnessed for osteochondral tissues: for cartilage it increased logarithmically (P < 0.05); for bone it decreased logarithmically (P < 0.05). The storage stiffness of osteochondral cores was logarithmically frequency-dependent (P < 0.05), however, the loss stiffness was typically frequency-independent (P > 0.05). A linear relationship between the subchondral bone plate (SBP) thickness and cartilage thickness (P < 0.001) was identified. Cartilage loss modulus was linearly correlated to bone mineral density (BMD) (P < 0.05) and bone volume (P < 0.05).

CONCLUSION

The relationship between the subchondral bone histomorphometry and cartilage viscoelasticity (namely loss modulus) and thickness, have implications for the initiation and progression of osteoarthritis (OA) through an altered ability of cartilage to dissipate energy.

Relative effects of age on implant integration in a rat model: A longitudinal in vivo microct study

The effect of age on implant fixation in bone is not always considered during the design of preclinical models. The decision on animal's age is often related to practical or historical reasons, which ultimately may affect the reproducibility of results. This study aimed to quantify the effect of age by monitoring the fixation of contrast-enhanced PEEK screws in rats, hypothesizing that the kinetics of fixation is impaired in older animals but that age effects are less severe than osteoporotic effects. The time course of implant fixation was investigated in healthy rats at 24, 40, and 60 weeks of age; and in ovariectomized rats. Implant fixation was monitored using in-vivo microCT and dynamic histomorphometry during 1 month. The rats were euthanized 28 days post screw insertion. The data was analyzed both in absolute value and after normalization to baseline bone mass. In absolute terms, greater age had a detrimental effect on bone implant contact, bone fraction, implant stiffness, and bone remodeling but less than ovariectomy. Interestingly, once data was normalized to baseline bone mass this effect disappeared, suggesting that the physiologic response to implant placement was not affected by age. In conclusion, implant fixation kinetics is less affected by age than by baseline bone mass in this rat model. Animals of different ages can therefore be compared but data must be construed relatively to baseline bone mass and not in absolute terms. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-12, 2018.

Fabrication of a nanoparticle-containing 3D porous bone scaffold with proangiogenic and antibacterial properties

3D porous scaffolds based on agarose and nanocrystalline apatite, two structural components that act as a temporary mineralized extracellular matrix, were prepared by the GELPOR3D method. This shaping technology allows the introduction of thermally-labile molecules within the scaffolds during the fabrication procedure. An angiogenic protein, Vascular Endothelial Growth Factor, and an antibiotic, cephalexin, loaded in mesoporous silica nanoparticles, were included to design multifunctional scaffolds for bone reconstruction. The dual release of both molecules showed a marked increase in the number of blood vessels on embryonic day 14 in chicken embryos grown ex ovo, while, at the same time providing an antibiotic local concentration capable of inhibiting Staphylococcus aureus bacterial growth. In this sense, different release patterns, monitored by UV-spectroscopy, could be tailored as a function of the cephalexin loading strategy, either releasing all the loaded cephalexin in the first 4 h or less than 50% after 24 h. The scaffold surface was characterized by a high hydrophilicity, with contact angles between 50° and 63°, which enabled the adhesion and proliferation of preosteoblastic cells. STATEMENT OF SIGNIFICANCE: The localized delivery of bioactive molecules has attracted significant attention due to the potential for dose reduction as well as reduced side effects compared to systemic delivery. In this article multifunctional 3D porous scaffolds with a designed porosity have been fabricated. The method also enables the controlled loading of an antibiotic drug and an angiogenic protein into the scaffold. These scaffolds, whose composition resembles the extracellular matrix are suitable for the adhesion of preosteoblast cells, exhibit a sustained cephalexin delivery adequate for inhibiting bacterial growth as well as release the proangiogenic molecule which induces blood vessel formation in chicken embryos grown ex ovo.

Tea consumption and bone health in Chinese adults: a population-based study

Tea is a worldwide drink with controversial effect on bone health. The sex-specific associations are unrevealed among general population. This study showed that prolonged moderate tea consumption benefited bone health in women, while no additional benefit with stronger tea. However, tea consumption was not associated with bone health in men.

INTRODUCTION

Tea consumption has been shown a potentially beneficial effect on bone health in postmenopausal women. However, little is known about such association in men, and whether stronger tea instead harms bone health due to elevated urinary excretion of calcium associated with caffeine in the tea. The aim of this study was to examine the association between various metrics of tea consumption and bone health.

METHODS

The present study included 20,643 participants from the China Kadoorie Biobank (CKB), who have finished both baseline survey (2004-2008) and a re-survey (2013-2014). They were aged 38-86 years at re-survey. Tea consumption was self-reported at both baseline and re-survey. Bone mineral density (BMD) was measured using calcaneal quantitative ultrasound once at re-survey.

RESULTS

Compared with non-consumers, prolonged weekly tea consumers in women was associated with higher calcaneus BMD measures, with β (95% CI) of 0.98 (0.22, 1.74) for BUA, 4.68 (1.74, 7.61) for SOS, and 1.95 (0.81, 3.10) for SI. Among prolonged weekly tea consumers, no linear increase in BMD measures with the amount of tea leaves added was observed. The SOS and SI were higher in consumers with tea leaves 3.0-5.9 g/day than in those with < 3.0 g/day, but were reduced to non-significant for those with ≥ 6.0 g/day. Tea consumption was not associated with calcaneus BMD measures in men.

CONCLUSION

Prolonged moderate tea consumption benefited bone health in women but not in men. For stronger tea consumption with more tea leaves added, neither benefit nor harm to bone health was observed.

Fermentation Improves the Preventive Effect of Soybean Against Bone Loss in Senescence-Accelerated Mouse Prone 6

Osteopenia is a preclinical phase of osteoporosis, it occurs naturally with aging and increases the risk of bone fractures in elderly males. Previous studies have revealed the beneficial effects of soybean on preventing bone loss due to its isoflavone contents. Fermentation alters the soybean isoflavone contents, that is, isoflavone glucosides is hydrolyzed into aglycones. However, it is not clear how these alterations influences the preventive effect of soybean on bone loss. In this study, we fed senescence-accelerated mouse prone 6 (SAMP6), a model of senile osteopenia, with an equal dosage of nonfermented soybean (NS) or fermented soybean, Doenjang (DJ) for 18 weeks. Mice supplemented with DJ showed 1.13-fold higher bone densities and 1.06-fold longer relative bone lengths than those of osteopenic SAMP6 mice old control (OC), while NS-supplemented mice showed no significant improvement. Supplementation with DJ effectively prevented bone loss in the osteopenia model by the improvement of bone formation and reduction of osteoclastogenesis. In addition, we discovered that DJ increased osteogenesis in SAMP6 mice via BMP2-Smad-Runx2 signaling. These results suggest that the fermentation process could enhance bone loss prevention by soybean and dietary supplementation with fermented soybeans may be beneficial for bone health. PRACTICAL APPLICATION: Soybean fermentation improved the preventive effects of soybean on bone loss. Therefore, the consumption of fermented soybean, Doenjang, is a potential alternative for aging-related bone loss therapy.

The role of sclerostin and dickkopf-1 in oral tissues - A review from the perspective of the dental disciplines

Wnt signaling is of high relevance in the development, homeostasis, and regeneration of oral tissues. Therefore, Wnt signaling is considered to be a potential target for therapeutic strategies. The action of Wnt is tightly controlled by the inhibitors sclerostin (SOST) and Dickkopf (DKK)-1. Given the impact of SOST and DKK-1 in hard tissue formation, related diseases and healing, it is of high relevance to understand their role in oral tissues. The clinical relevance of this knowledge is further underlined by systemic and local approaches which are currently in development for treating a variety of diseases such as osteoporosis and inflammatory hard tissue resorption. In this narrative review, we summarize the current knowledge and understanding on the Wnt signaling inhibitors SOST and DKK-1, and their role in physiology, pathology, and regeneration in oral tissues. We present this role from the perspective of the different specialties in dentistry, including endodontics, orthodontics, periodontics, and oral surgery.

A cross-sectional study on the age-related cortical and trabecular bone changes at the femoral head in elderly female hip fracture patients

Bone is in a continuous state of remodeling whereby old bone is absorbed and new bone is formed in its place. During this process, new formations reinforce the bone in the direction of the dominant stress trajectories through a functional adaptation. In normal aging, the balance between bone resorption and formation can be shifted. How this affects the functional adaptation remains to be investigated. Furthermore, how or whether the bone continues to change beyond the age of 85 is not yet studied in detail. In this study we examined the age-related changes in the cortical and trabecular bone in old age, and assessed whether we can find evidence of the presence of functional adaptation. We measured cortical and trabecular parameters from micro-computed tomography scans of the femoral head extracted from hip fracture patients between the age of 70 and 93 years. A significant decrease in global trabecular bone mineral density (38.1%) and cortical thickness (13.0%) was seen from the 9th to the 10th decade of life. The degree of anisotropy was maintained globally as well as locally in both high and low stress regions. The local trabecular bone mineral density decreased in both high stress and low stress regions between the 9th and 10th decade of life with similar trends. This suggests that the role of functional adaptation in maintaining the bone structural integrity in old age may be limited. This study highlights the need for a controlled clinical trial examining the cause of the continued bone degradation throughout old age.

Masquelet Technique: Effects of Spacer Material and Micro-topography on Factor Expression and Bone Regeneration

We and others have shown that changing surface characteristics of the spacer implanted during the first Masquelet stage alters some aspects of membrane development. Previously we demonstrated that titanium (TI) spacers create membranes that are better barriers to movement of solutes > 70 kDa in size than polymethyl methacrylate (PMMA) induced-membranes, and roughening creates more mechanically compliant membranes. However, it is unclear if these alterations affect the membrane's biochemical environment or bone regeneration during the second stage. Ten-week-old, male Sprague-Dawley rats underwent an initial surgery to create an externally stabilized 6 mm femoral defect. PMMA or TI spacers with smooth (~ 1 μm) or roughened (~ 8 μm) surfaces were implanted. Four weeks later, rats were either euthanized for membrane harvest or underwent the second Masquelet surgery. TI spacers induced thicker membranes that were similar in structure and biochemical expression. All membranes were bilayered with the inner layer having increased factor expression [bone morphogenetic protein 2 (BMP2), transforming growth factor beta (TGFβ), interleukin 6 (IL6), and vascular endothelial growth factor (VEGF)]. Roughening increased overall IL6 levels. Ten-weeks post-engraftment, PMMA-smooth induced membranes better supported bone regeneration (60% union). The other groups only had 1 or 2 that united (9-22%). There were no significant differences in any micro computed tomography or dynamic histology outcome. In conclusion, this study suggests that the membrane's important function in the Masquelet technique is not simply as a barrier. There is likely a critical biochemical, cellular, or vascular component as well.

Computational investigation of ultrastructural behavior of bone using a cohesive finite element approach

Bone ultrastructure at sub-lamellar length scale is a key structural unit in bone that bridges nano- and microscale hierarchies of the tissue. Despite its influence on bulk response of bone, the mechanical behavior of bone at ultrastructural level remains poorly understood. To fill this gap, in this study, a two-dimensional cohesive finite element model of bone at sub-lamellar level was proposed and analyzed under tensile and compressive loading conditions. In the model, ultrastructural bone was considered as a composite of mineralized collagen fibrils (MCFs) embedded in an extrafibrillar matrix (EFM) that is comprised of hydroxyapatite (HA) polycrystals bounded via thin organic interfaces of non-collagenous proteins (NCPs). The simulation results indicated that in compression, EFM dictated the pre-yield deformation of the model, then damage was initiated via relative sliding of HA polycrystals along the organic interfaces, and finally shear bands were formed followed by delamination between MCF and EFM and local buckling of MCF. In tension, EFM carried the most of load in pre-yield deformation, and then an array of opening-mode nano-cracks began to form within EFM after yielding, thus gradually transferring the load to MCF until failure, which acted as crack bridging filament. The failure modes, stress-strain curves, and in situ mineral strain of ultrastructural bone predicted by the model were in good agreement with the experimental observations reported in the literature, thus suggesting that this model can provide new insights into sub-microscale mechanical behavior of bone.

Vibrational spectroscopic analysis of hydroxyapatite in HYP mice and individuals with X-linked hypophosphatemia

BACKGROUND

X-linked hypophosphatemia (XLH) is the most common form of familial phosphate-wasting disorders, due to an inactivating mutation in the phosphate-regulating neutral endopeptidase, X-linked gene. Persistent osteomalacia, enthesophytes, osteophytes, degenerative arthritis and dental abscesses/periodontal disease dominate the adult disorder. However, the impact of insufficient phosphate on hydroxyapatite composition, the major inorganic component of bone and teeth, is unknown in individuals with XLH.

METHODS

Using Raman spectroscopy, the carbonate (CO3 2-) to phosphate (PO4 3-) ion ratio was measured in HYP and wild-type mice and in primary and permanent teeth from XLH individuals and unaffected controls.

RESULTS

There was a significant difference in carbonate ion substitution between the HYP and wild-type femoral cortical bone (0.36 ± 0.08 versus 0.24 ± 0.04; p < 0.001). Carbonate ion substitution levels were also higher in permanent XLH teeth compared with unaffected individuals (0.39 ± 0.12 versus 0.23 ± 0.04; p < 0.001), but not in primary teeth (0.29 ± 0.11 versus 0.26 ± 0.02; p = 0.29). Complementary Fourier transform infrared analyses demonstrated higher relative intensities of the four major vibrational bands originating from the carbonate anion in XLH teeth compared with unaffected controls.

CONCLUSION

Ionic substitution within the crystal lattice is a common feature of hydroxyapatite and one that confers the physiological properties of bone that impact mechanical strength and the process of bone remodeling. Our data demonstrating anionic substitution in human dentin from individuals with XLH validate the use of dentin as a proxy for bone and to better understand the molecular adaptations that occur in the biochemical milieu of XLH.

Biomimetic matrices for rapidly forming mineralized bone tissue based on stem cell-mediated osteogenesis

Bone regeneration, following fracture, relies on autologous and allogenic bone grafts. However, majority of fracture population consists of older individuals with poor quality bone associated with loss and/or modification of matrix proteins critical for bone formation and mineralization. Allografts suffer from same limitations and carry the risk of delayed healing, infection, immune rejection and eventual fracture. In this work, we apply a synergistic biomimetic strategy to develop matrices that rapidly form bone tissue - a critical aspect of fracture healing of weight bearing bones. Collagen matrices, enhanced with two selected key matrix proteins, osteocalcin (OC) and/or osteopontin (OPN), increased the rate and quantity of synthesized bone matrix by increasing mesenchymal stem/stromal cell (MSC) proliferation, accelerating osteogenic differentiation, enhancing angiogenesis and showing a sustained bone formation response from MSC obtained from a variety of human tissue sources (marrow, fat and umbilical cord). In vivo assessment of OC/OPN mineralized scaffolds in a critical sized-defect rabbit long-bone model did not reveal any foreign body reaction while bone tissue was being formed. We demonstrate a new biomimetic strategy to rapidly form mineralized bone tissue and secure a sustained bone formation response by MSC from multiple sources, thus facilitating faster patient recovery and treatment of non-union fractures in aging and diseased population. Acellular biomimetic matrices elicit bone regeneration response from MSC, obtained from multiple tissue sources, and can be used in variety of scaffolds and made widely available.