Diabetes causes the accelerated loss of cartilage during fracture repair which is reversed by insulin treatment

U-shaped association between triglyceride glucose-body mass index with all-cause and cardiovascular mortality in US adults with osteoarthritis: evidence from NHANES 1999-2020

The association between insulin resistance (IR) and the risk of all-cause mortality and cardiovascular mortality among osteoarthritis (OA) patients remains uncertain. This study aims to clarify the correlation between a novel marker of IR, the triglyceride glucose-body mass index (TyG-BMI), and the risk of all-cause mortality and cardiovascular mortality in OA patients. Data from the National Health and Nutrition Examination Survey (NHANES) spanning from 1999 to 2020 were analyzed. Multivariable Cox proportional hazards regression analysis and restricted cubic spline plots were employed to elucidate the association between the TyG-BMI index and the risk of all-cause mortality or cardiovascular mortality in OA patients. Additionally, subgroup analysis was conducted to explore potential interactions and identify populations at elevated risk of mortality. The study cohort comprised 4097 OA patients who were followed up for a period of 20 years, during which 1197 cases of all-cause mortality and 329 cases of mortality attributed to cardiovascular disease were recorded. Our findings revealed a U-shaped nonlinear relationship between the TyG-BMI index and the risk of all-cause mortality or cardiovascular mortality in OA patients, with the lowest mortality risk thresholds identified at 282 and 270, respectively. Moreover, surpassing these thresholds was associated with a 3% increase in the risk of all-cause mortality and a 5% increase in the risk of cardiovascular mortality for every 10-unit increment in TyG-BMI level. Among American OA patients, a U-shaped nonlinear relationship exists between the TyG-BMI index and the risk of all-cause mortality or cardiovascular mortality. These findings underscore the significant role of IR in the progression of OA.

Advantages and Limitations of Diabetic Bone Healing in Mouse Models: A Narrative Review

Diabetes represents a major risk factor for impaired fracture healing. Type 2 diabetes mellitus is a growing epidemic worldwide, hence an increase in diabetes-related complications in fracture healing can be expected. However, the underlying mechanisms are not yet completely understood. Different mouse models are used in preclinical trauma research for fracture healing under diabetic conditions. The present review elucidates and evaluates the characteristics of state-of-the-art murine diabetic fracture healing models. Three major categories of murine models were identified: Streptozotocin-induced diabetes models, diet-induced diabetes models, and transgenic diabetes models. They all have specific advantages and limitations and affect bone physiology and fracture healing differently. The studies differed widely in their diabetic and fracture healing models and the chosen models were evaluated and discussed, raising concerns in the comparability of the current literature. Researchers should be aware of the presented advantages and limitations when choosing a murine diabetes model. Given the rapid increase in type II diabetics worldwide, our review found that there are a lack of models that sufficiently mimic the development of type II diabetes in adult patients over the years. We suggest that a model with a high-fat diet that accounts for 60% of the daily calorie intake over a period of at least 12 weeks provides the most accurate representation.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Reduced Bone Regeneration in Rats With Type 2 Diabetes Mellitus as a Result of Impaired Stromal Cell and Osteoblast Function-A Computer Modeling Study

Bone has the fascinating ability to self-regenerate. However, under certain conditions, such as type 2 diabetes mellitus (T2DM), this ability is impaired. T2DM is a chronic metabolic disease known by the presence of elevated blood glucose levels that is associated with reduced bone regeneration capability, high fracture risk, and eventual non-union risk after a fracture. Several mechanical and biological factors relevant to bone regeneration have been shown to be affected in a diabetic environment. However, whether impaired bone regeneration in T2DM can be explained due to mechanical or biological alterations remains unknown. To elucidate the relevance of either one, the aim of this study was to investigate the relative contribution of T2DM-related alterations on either cellular activity or mechanical stimuli driving bone regeneration. A previously validated in silico computer modeling approach that was capable of explaining bone regeneration in uneventful conditions of healing was further developed to investigate bone regeneration in T2DM. Aspects analyzed included the presence of mesenchymal stromal cells (MSCs), cellular migration, proliferation, differentiation, apoptosis, and cellular mechanosensitivity. To further verify the computer model findings against in vivo data, an experimental setup was replicated, in which regeneration was compared in healthy and diabetic after a rat femur bone osteotomy stabilized with plate fixation. We found that mechanical alterations had little effect on the reduced bone regeneration in T2DM and that alterations in MSC proliferation, MSC migration, and osteoblast differentiation had the highest effect. In silico predictions of regenerated bone in T2DM matched qualitatively and quantitatively those from ex vivo μCT at 12 weeks post-surgery when reduced cellular activities reported in previous in vitro and in vivo studies were included in the model. The presented findings here could have clinical implications in the treatment of bone fractures in patients with T2DM. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Injectable hydrogel for sustained delivery of progranulin derivative Atsttrin in treating diabetic fracture healing

Hydrogels with long-term storage stability, controllable sustained-release properties, and biocompatibility have been garnering attention as carriers for drug/growth factor delivery in tissue engineering applications. Chitosan (CS)/Graphene Oxide (GO)/Hydroxyethyl cellulose (HEC)/β-glycerol phosphate (β-GP) hydrogel is capable of forming a 3D gel network at physiological temperature (37 °C), rendering it an excellent candidate for use as an injectable biomaterial. This work focused on an injectable thermo-responsive CS/GO/HEC/β-GP hydrogel, which was designed to deliver Atsttrin, an engineered derivative of a known chondrogenic and anti-inflammatory growth factor-like molecule progranulin. The combination of the CS/GO/HEC/β-GP hydrogel and Atsttrin provides a unique biochemical and biomechanical environment to enhance fracture healing. CS/GO/HEC/β-GP hydrogels with increased amounts of GO exhibited rapid sol-gel transition, higher viscosity, and sustained release of Atsttrin. In addition, these hydrogels exhibited a porous interconnected structure. The combination of Atsttrin and hydrogel successfully promoted chondrogenesis and osteogenesis of bone marrow mesenchymal stem cells (bmMSCs) in vitro. Furthermore, the work also presented in vivo evidence that injection of Atsttrin-loaded CS/GO/HEC/β-GP hydrogel stimulated diabetic fracture healing by simultaneously inhibiting inflammatory and stimulating cartilage regeneration and endochondral bone formation signaling pathways. Collectively, the developed injectable thermo-responsive CS/GO/HEC/βG-P hydrogel yielded to be minimally invasive, as well as capable of prolonged and sustained delivery of Atsttrin, for therapeutic application in impaired fracture healing, particularly diabetic fracture healing.

FOXO 1 deletion in chondrocytes rescues diabetes-impaired fracture healing by restoring angiogenesis and reducing apoptosis

Introduction

Diabetes mellitus is associated with higher risks of long bone and jaw fractures. It is also associated with a higher incidence of delayed union or non-union. Our previous investigations concluded that a dominant mechanism was the premature loss of cartilage during endochondral bone formation associated with increased osteoclastic activities. We tested the hypothesis that FOXO1 plays a key role in diabetes-impaired angiogenesis and chondrocyte apoptosis.

Methods

Closed fractures of the femur were induced in mice with lineage-specific FOXO1 deletion in chondrocytes. The control group consisted of mice with the FOXO1 gene present. Mice in the diabetic group were rendered diabetic by multiple streptozotocin injections, while mice in the normoglycemic group received vehicle. Specimens were collected 16 days post fracture. The samples were fixed, decalcified, and embedded in paraffin blocks for immunostaining utilizing anti cleaved caspase-3 or CD31 specific antibodies compared with matched control IgG antibody, and apoptosis by the TUNEL assay. Additionally, ATDC5 chondrocytes were examined in vitro by RT-PCR, luciferase reporter and chromatin immunoprecipitation assays.

Results

Diabetic mice had ~ 50% fewer blood vessels compared to normoglycemic mice FOXO1 deletion in diabetic mice partially rescued the low number of blood vessels (p < 0.05). Additionally, diabetes increased caspase-3 positive and apoptotic chondrocytes by 50%. FOXO1 deletion in diabetic animals blocked the increase in both to levels comparable to normoglycemic animals (p < 0.05). High glucose (HG) and high advanced glycation end products (AGE) levels stimulated FOXO1 association with the caspase-3 promoter in vitro, and overexpression of FOXO1 increased caspase-3 promoter activity in luciferase reporter assays. Furthermore, we review previous mechanistic studies demonstrating that tumor necrosis factor (TNF) inhibition reverses impaired angiogenesis and reverses high levels of chondrocyte apoptosis that occur in fracture healing.

Discussion

New results presented here, in combination with recent studies, provide a comprehensive overview of how diabetes, through high glucose levels, AGEs, and increased inflammation, impair the healing process by interfering with angiogenesis and stimulating chondrocyte apoptosis. FOXO1 in diabetic fractures plays a negative role by reducing new blood vessel formation and increasing chondrocyte cell death which is distinct from its role in normal fracture healing.

Norisoboldine, a Natural Isoquinoline Alkaloid, Inhibits Diaphyseal Fracture Healing in Mice by Alleviating Cartilage Formation

Norisoboldine (NOR), the major isoquinoline alkaloid constituent of a Chinese traditional medicine Radix Linderae, has been demonstrated to inhibit osteoclast differentiation and improve arthritis. The aim of this study is to examine the effect of NOR on bone fracture healing and the underlying mechanisms correlated with bone marrow stromal cells (BMSCs) differentiation to chondrocytes. Our results showed that NOR inhibits the tibia fracture healing process by suppressing cartilage formation, which leads to less endochondral ossification, indicated by less osterix and collage I signaling at the fracture site. Moreover, NOR significantly reduced the differentiation of primary BMSCs to chondrocytes in vitro by reducing the bone morphogenetic protein 2 (BMP2) signaling. These findings imply that NOR negatively regulates the healing of the tibial midshaft fracture, which might delay the union of the fractures and should be noticed when used in other treatments.

Beyond mechanical loading: The metabolic contribution of obesity in osteoarthritis unveils novel therapeutic targets

Osteoarthritis (OA) is a prevalent progressive disease that frequently coexists with obesity. For several decades, OA was thought to be the result of ageing and mechanical stress on cartilage. Researchers' perspective has been greatly transformed when cumulative findings emphasized the role of adipose tissue in the diseases. Nowadays, the metabolic effect of obesity on cartilage tissue has become an integral part of obesity research; hoping to discover a disease-modifying drug for OA. Recently, several adipokines have been reported to be associated with OA. Particularly, metrnl (meteorin-like) and retinol-binding protein 4 (RBP4) have been recognized as emerging adipokines that can mediate OA pathogenesis. Accordingly, in this review, we will summarize the latest findings concerned with the metabolic contribution of obesity in OA pathogenesis, with particular emphasis on dyslipidemia, insulin resistance and adipokines. Additionally, we will discuss the most recent adipokines that have been reported to play a role in this context. Careful consideration of these molecular mechanisms interrelated with obesity and OA will undoubtedly unveil new avenues for OA treatment.

Liraglutide in Combination with Insulin Has a Superior Therapeutic Effect to Either Alone on Fracture Healing in Diabetic Rats

Purpose

Fractures in patients with type 2 diabetes mellitus are at a high risk of delayed union or non-union. Previous studies have shown a protective effect of liraglutide on bone. In the present study, we aimed to investigate the effects of a combination of liraglutide and insulin on fracture healing in a rat model of diabetes and the mechanisms involved.

Materials and Methods

Closed femoral mid-shaft fractures were established in male Sprague-Dawley rats with or without diabetes mellitus, and the diabetic rats were administered insulin and/or liraglutide. Six weeks after femoral fracture, the femoral callus was evaluated by immunohistochemistry, histology, and micro-computed tomography. Additionally, the effects of liraglutide on high-glucose-stimulated MC3T3-E1 cells were analyzed by Western blotting.

Results

Micro-computed tomography and safranin O/fast green staining showed that fracture healing was delayed in the diabetic rats, and this was accompanied by much lower expression of osteogenic markers and greater osteoclast activity. However, treatment with insulin and/or liraglutide prevented these changes. Liraglutide in combination with insulin treatment resulted in lower blood glucose concentrations and significantly higher osteocalcin (OCN) and collagen I (Col I) expression six weeks following fracture. Western blot analysis showed that liraglutide prevented the low expression of the bone morphogenetic protein-2, osterix/SP7, OCN, Col I, and β-catenin in high-glucose-stimulated MC3T3-E1 cells.

Conclusion

These results demonstrate that insulin and/or liraglutide promotes bone fracture healing in the DF model. The combination was more effective than either single treatment, which may be because of the two drugs' additive effects on the osteogenic ability of osteoblast precursors.

Local zinc treatment enhances fracture callus properties in diabetic rats

The effects of locally applied zinc chloride (ZnCl₂ ) on early and late-stage parameters of fracture healing were evaluated in a diabetic rat model. Type 1 Diabetes has been shown to negatively impact mechanical parameters of bone as well as biologic markers associated with bone healing. Zinc treatments have been shown to reverse those outcomes in tests of nondiabetic and diabetic animals. This study is the first to assess the efficacy of a noncarrier mediated ZnCl₂ on bony healing in diabetic animals. This is a promising basic science approach which may lead to benefits for diabetic patients in the future. Treatment and healing were assessed through quantification of callus zinc, radiographic scoring, microcomputed tomography (µCT), histomorphometry, and mechanical testing. Local ZnCl₂ treatment increased callus zinc levels at 1 and 3 days after fracture (p ≤ 0.025). Femur fractures treated with ZnCl₂ showed increased mechanical properties after 4 and 6 weeks of healing. Histomorphometry of the ZnCl₂ -treated fractures found increased callus cartilage area at Day 7 (p = 0.033) and increased callus bone area at Day 10 (p = 0.038). In contrast, callus cartilage area was decreased (p < 0.01) after 14 days in the ZnCl₂ -treated rats. µCT analysis showed increased bone volume in the fracture callus of ZnCl₂ -treated rats at 6 weeks (p = 0.0012) with an associated increase in the proportion of µCT voxel axial projections (Z-rays) spanning the fracture site. The results suggest that local ZnCl₂ administration improves callus chondrogenesis leading to greater callus bone formation and improved fracture healing in diabetic rats.

Fracture Healing in the Setting of Endocrine Diseases, Aging, and Cellular Senescence

More than 2.1 million age-related fractures occur in the United States annually, resulting in an immense socioeconomic burden. Importantly, the age-related deterioration of bone structure is associated with impaired bone healing. Fracture healing is a dynamic process which can be divided into four stages. While the initial hematoma generates an inflammatory environment in which mesenchymal stem cells and macrophages orchestrate the framework for repair, angiogenesis and cartilage formation mark the second healing period. In the central region, endochondral ossification favors soft callus development while next to the fractured bony ends, intramembranous ossification directly forms woven bone. The third stage is characterized by removal and calcification of the endochondral cartilage. Finally, the chronic remodeling phase concludes the healing process. Impaired fracture healing due to aging is related to detrimental changes at the cellular level. Macrophages, osteocytes, and chondrocytes express markers of senescence, leading to reduced self-renewal and proliferative capacity. A prolonged phase of "inflammaging" results in an extended remodeling phase, characterized by a senescent microenvironment and deteriorating healing capacity. Although there is evidence that in the setting of injury, at least in some tissues, senescent cells may play a beneficial role in facilitating tissue repair, recent data demonstrate that clearing senescent cells enhances fracture repair. In this review, we summarize the physiological as well as pathological processes during fracture healing in endocrine disease and aging in order to establish a broad understanding of the biomechanical as well as molecular mechanisms involved in bone repair.

Monocyte Chemotactic Proteins Mediate the Effects of Hyperglycemia in Chondrocytes: In Vitro Studies

Chemokines are secreted by a large variety of cells. They are involved in controlling cell trafficking, maturation, and differentiation. However, the specific responses and effects of chemokines on specific skeletal cell types under high glucose conditions have not been investigated. Chondrocytes play an important role in osteoarthritis and fracture healing. Delayed fracture healing is one of the major health complications caused by diabetes, so the goal of this study was to evaluate the response of several chemokines to high glucose conditions in chondrocyte cells and analyze their role in the catabolic effect of hyperglycemia. ATDC5 chondrocytes were cultured in normal and high glucose media, and mRNA expression levels of several chemokines and chondrocyte differentiation markers were quantified. Bindarit, a specific inhibitor of monocyte chemotactic proteins (MCPs), was used to determine the role of MCPs in mediating the effects of high glucose conditions in chondrocyte cells. High glucose treatment upregulated the expression of three Mcps, as well as the expression of matrix metalloproteinase 13 (Mmp13) and Osteocalcin (Oc). Furthermore, bindarit treatment downregulated Mmp13 and Oc but upregulated Collagen 2 (Col2) mRNA levels in chondrocytes treated with high glucose. Moreover, treatment of chondrocytes with ascorbic acid reduced the effect of high glucose conditions on the expression of chemokines and Mmps. These data together suggest that MCPs mediate the catabolic effect of high glucose in chondrocytes.

Vibration therapy as an effective approach to improve bone healing in diabetic rats

OBJECTIVE

To investigate the effects of vibration therapy on fracture healing in diabetic and non-diabetic rats.

METHODS

148 rats underwent fracture surgery and were assigned to four groups: (1) SHAM: weight-matched non-diabetic rats, (2) SHAM+VT: non-diabetic rats treated with vibration therapy (VT), (3) DM: diabetic rats, and (4) DM+VT: diabetic rats treated with VT. Thirty days after diabetes induction with streptozotocin, animals underwent bone fracture, followed by surgical stabilization. Three days after bone fracture, rats began VT. Bone healing was assessed on days 14 and 28 post-fracture by serum bone marker analysis, and femurs collected for dual-energy X-ray absorptiometry, micro-computed tomography, histology, and gene expression.

RESULTS

Our results are based on 88 animals. Diabetes led to a dramatic impairment of bone healing as demonstrated by a 17% reduction in bone mineral density and decreases in formation-related microstructural parameters compared to non-diabetic control rats (81% reduction in bone callus volume, 69% reduction in woven bone fraction, 39% reduction in trabecular thickness, and 45% in trabecular number). These changes were accompanied by a significant decrease in the expression of osteoblast-related genes (Runx2, Col1a1, Osx), as well as a 92% reduction in serum insulin-like growth factor I (IGF-1) levels. On the other hand, resorption-related parameters were increased in diabetic rats, including a 20% increase in the callus porosity, a 33% increase in trabecular separation, and a 318% increase in serum C terminal telopeptide of type 1 collagen levels. VT augmented osteogenic and chondrogenic cell proliferation at the fracture callus in diabetic rats; increased circulating IGF-1 by 668%, callus volume by 52%, callus bone mineral content by 90%, and callus area by 72%; and was associated with a 19% reduction in circulating receptor activator of nuclear factor kappa beta ligand (RANK-L).

CONCLUSIONS

Diabetes had detrimental effects on bone healing. Vibration therapy was effective at counteracting the significant disruption in bone repair induced by diabetes, but did not improve fracture healing in non-diabetic control rats. The mechanical stimulus not only improved bone callus quality and quantity, but also partially restored the serum levels of IGF-1 and RANK-L, inducing bone formation and mineralization, thus creating conditions for adequate fracture repair in diabetic rats.

Type 1 diabetic Akita mice have low bone mass and impaired fracture healing

Type 1 diabetes (T1DM) impairs bone formation and fracture healing in humans. Akita mice carry a mutation in one allele of the insulin-2 (Ins2) gene, which leads to pancreatic beta cell dysfunction and hyperglycemia by 5-6 weeks age. We hypothesized that T1DM in Akita mice is associated with decreased bone mass, weaker bones, and impaired fracture healing. Ins2 ± (Akita) and wildtype (WT) males were subjected to femur fracture at 18-weeks age and healing assessed 3-21 days post-fracture. Non-fractured left femurs were assessed for morphology (microCT) and strength (bending or torsion) at 19-21 weeks age. Fractured right femurs were assessed for callus mechanics (torsion), morphology and composition (microCT and histology) and gene expression (qPCR). Both Akita and WT mice gained weight from 3 to 18 weeks age, but Akita mice weighed less starting at 5 weeks (-5.2%, p < 0.05). At 18-20 weeks age Akita mice had reduced serum osteocalcin (-30%), cortical bone area (-16%), and thickness (-17%) compared to WT, as well as reduced cancellous BV/TV (-39%), trabecular thickness (-23%) and vBMD (-31%). Mechanical testing of non-fractured femurs showed decreased structural (stiffness, ultimate load) and material (ultimate stress) properties of Akita bones. At 14 and 21 days post fracture Akita mice had a significantly smaller callus than WT mice (~30%), with less cartilage and bone area. Assessment of torsional strength showed a weaker callus in Akita mice with lower stiffness (-42%), maximum torque (-44%) and work to fracture (-44%). In summary, cortical and cancellous bone mass were reduced in Akita mice, with lower bone mechanical properties. Fracture healing in Akita mice was impaired by T1DM, with a smaller, weaker fracture callus due to decreased cartilage and bone formation. In conclusion, the Akita mouse mimics some of the skeletal features of T1DM in humans, including osteopenia and impaired fracture healing, and may be useful to test interventions.

Progranulin promotes bone fracture healing via TNFR pathways in mice with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) significantly increases bone fragility and fracture risk. Progranulin (PGRN) promotes bone fracture healing in both physiological and type 1 diabetic conditions. The present study aimed to investigate the role of PGRN in T2DM bone fracture healing. MKR mice (with an FVB/N genetic background) were used as the T2DM model. Drill-hole and Bonnarens and Einhorn models were used to investigate the role of PGRN in T2DM fracture healing in vivo. Primary bone marrow cells were isolated for molecular and signaling studies, and reverse transcription-polymerase chain reaction, immunohistochemical staining, and western blotting were performed to assess PGRN effects in vitro. PGRN mRNA and protein expression were upregulated in the T2DM model. Local administration of recombinant PGRN effectively promoted T2DM bone fracture healing in vivo. Additionally, PGRN could induce anabolic metabolism during endochondral ossification through the TNFR2-Akt and Erk1/2 pathways. Furthermore, PGRN showed anti-inflammatory activity in the T2DM bone regeneration process. These findings suggest that local administration of exogenous PGRN may be an alternative strategy to support bone regeneration in patients with T2DM. Additionally, PGRN might hold therapeutic potential for other TNFR-related metabolic disorders.

Modeling Complex Orthopedic Trauma in Rodents: Bone, Muscle and Nerve Injury and Healing

Orthopedic injury can occur from a variety of causes including motor vehicle collision, battlefield injuries or even falls from standing. Persistent limb pain is common after orthopedic injury or surgery and presents a unique challenge, as the initiating event may result in polytrauma to bone, muscle, and peripheral nerves. It is imperative that we understand the tissue-specific and multicellular response to this unique type of injury in order to best develop targeted treatments that improve healing and regeneration. In this Mini Review we will first discuss current rodent models of orthopedic trauma/complex orthotrauma. In the second section, we will focus on bone-specific outcomes including imaging modalities, biomechanical testing and immunostaining for markers of bone healing/turnover. In the third section, we will discuss muscle-related pathology including outcome measures of fibrosis, muscle regeneration and tensile strength measurements. In the fourth section, we will discuss nervous system-related pathology including outcome measures of pain-like responses, both reflexive and non-reflexive. In all sections we will consider parallels between preclinical outcome measures and the functional and mechanistic findings of the human condition.

Diabetes impairs periosteal progenitor regenerative potential

Diabetics are at increased risk for fracture, and experience severely impaired skeletal healing characterized by delayed union or nonunion of the bone. The periosteum harbors osteochondral progenitors that can differentiate into chondrocytes and osteoblasts, and this connective tissue layer is required for efficient fracture healing. While bone marrow-derived stromal cells have been studied extensively in the context of diabetic skeletal repair and osteogenesis, the effect of diabetes on the periosteum and its ability to contribute to bone regeneration has not yet been explicitly evaluated. Within this study, we utilized an established murine model of type I diabetes to evaluate periosteal cell differentiation capacity, proliferation, and availability under the effect of a diabetic environment. Periosteal cells from diabetic mice were deficient in osteogenic differentiation ability in vitro, and diabetic mice had reduced periosteal populations of mesenchymal progenitors with a corresponding reduction in proliferation capacity following injury. Additionally, fracture callus mineralization and mature osteoblast activity during periosteum-mediated healing was impaired in diabetic mice compared to controls. We propose that the effect of diabetes on periosteal progenitors and their ability to aid in skeletal repair directly impairs fracture healing.

Serum MicroRNA Differences Between Fracture in Postmenopausal Women with and without Diabetes

OBJECTIVE

To screen serum microRNAs (miRNAs) which could discriminate fracture status in postmenopausal women with or without diabetes.

METHODS

The miRNA expression profile dataset GSE70318 was downloaded from Gene Expression Omnibus (GEO) database. This dataset composed of 74 samples, among these, 55 postmenopausal women was selected for bioinformatics analysis, including 19 osteoporotic fracture patients with type-2 diabetes, 19 osteoporotic fracture patients without type-2 diabetes, and 17 healthy control subjects. These samples were divided into two groups: fracture patients with diabetes vs healthy subjects (FH group) and fracture patients without diabetes vs healthy subjects (DFH group). Then, the differentially expressed miRNA (DEMs) in FH group and DFH group were respectively identified. The target genes of DEMs were predicted, followed by functional enrichment analysis. Furthermore, DEMs related to long non-coding RNAs (lncRNAs) were screened, and DEMs-lncRNA-target genes network was constructed. Subsequently, principal component analysis (PCA) of DEMs was performed to further explore the expression characteristics of the selected miRNAs in different types of fracture samples. Finally, the expression level of significant DEMs was calculated by quantitative real-time polymerase chain reaction (qPCR) to verify the accuracy of the results of bioinformatics analysis.

RESULTS

A total of 18 and 23 DEMs were identified in FH and DFH groups, respectively. Gene ontology (GO) analysis showed that genes in FH group were significantly enriched in regulation of transcription (GO: 0045449) and genes in DFH group were mainly enriched in cellular response to hormone stimulus (GO: 0032870). Meanwhile, pathway analysis indicated that genes in FH group were primarily enriched in T cell receptor signaling pathway (hsa04660) and genes in DFH group were mainly implicated in neurotrophin-signaling pathway (hsa04722). Moreover, the miRNA-lncRNA analysis revealed that miR-155-5p regulated by lncRNA MIR155HG was up-regulated in FH group; in addition, the miR-181c was significantly up-regulated and miR-375 was observably down-regulated in DFH group. Furthermore, PCA analysis suggested that the screened miRNAs were able to differentiate these two types of fractures in postmenopausal women. The miR-181c and miR-375 might be regarded as potential predictors for fracture, while miR-155-5p might be a candidate diagnostic biomarker for diabetic fracture. Finally, the results of qPCR were consistent with that of microarray data.

CONCLUSIONS

Overall, these three miRNAs might be regarded as potential diagnostic biomarkers to discriminate fracture status in postmenopausal women with and or without diabetes, and they served a putative role in the pathogenesis of these two diseases. However, these findings were only observed in serum samples and further clinical trials are urgently demanded to validate our results.

Outcome of fragility hip fractures in elderly patients: Does diabetes mellitus and its severity matter?

AIMS

Diabetes mellitus (DM) and osteoporosis are both diseases of epidemic proportions with an increasing incidence worldwide. Fragility hip fractures (FHF) are associated with elevated morbidity, mortality, social burden and medical costs. The aim of this study was to determine whether patients with DM have worse medical and surgical outcomes following FHFs and whether the Diabetes Complications Severity Index (DCSI) can predict in-hospital complications and one-year mortality.

METHODS

A single centre retrospective cohort study including 1343 patients older than 65 years who underwent surgery for FHFs was conducted. The data collected included length of hospital stay, time-to-surgery, blood loss, complications and mortality during the first post-operative year.

RESULTS

408 patients with a DM diagnosis were compared with 935 without DM. Pre-operatively, patients with DM had lower haemoglobin levels, higher platelet counts and worse renal function. Following surgery, patients with DM were more likely to be transferred to another department or intensive care. One-year mortality was significantly higher in the DM group [23.3% vs. 17.1%, odds ratio 1.36 (CI 1.029-1.799, p = 0.03)]. Higher DCSI scores were related with elevated one-year mortality rates in the DM group. Cerebrovascular events were found to be nearly five times more prevalent in the DM group. Patients with DM were more likely to continue treatment in a rehabilitation centre and had a higher probability to be re-hospitalized in the first post-operative year (p.<0.001).

CONCLUSIONS

Our results emphasize the increased vulnerability of this patient population and the importance of specialized care during the peri-operative period of FHFs.

Low Intensity Pulsed Ultrasound Therapy (LIPUS): A review of evidence and potential applications in diabetics

Low Intensity Pulsed Ultrasound Therapy (LIPUS) is a non-invasive treatment and aims to reduce fracture healing time and avoid non-union by delivering micro-mechanical stress to the bone to stimulate bone healing. In 2018, the National Institute for Health and Clinical Excellence (NICE) recommended that the evidence for LIPUS to promote healing of delayed-union and non-union fractures raised no major safety concerns, but the current evidence on efficacy is inadequate in quality. Little is known about the potential benefits of LIPUS for fracture healing in diabetic patients. In this article, we review the current evidence of LIPUS therapy both in animal and human studies and its possible application on fractures in diabetics.

Insulin Resistance in Osteoarthritis: Similar Mechanisms to Type 2 Diabetes Mellitus

Osteoarthritis (OA) and type 2 diabetes mellitus (T2D) are two of the most widespread chronic diseases. OA and T2D have common epidemiologic traits, are considered heterogenic multifactorial pathologies that develop through the interaction of genetic and environmental factors, and have common risk factors. In addition, both of these diseases often manifest in a single patient. Despite differences in clinical manifestations, both diseases are characterized by disturbances in cellular metabolism and by an insulin-resistant state primarily associated with the production and utilization of energy. However, currently, the primary cause of OA development and progression is not clear. In addition, although OA is manifested as a joint disease, evidence has accumulated that it affects the whole body. As pathological insulin resistance is viewed as a driving force of T2D development, now, we present evidence that the molecular and cellular metabolic disturbances associated with OA are linked to an insulin-resistant state similar to T2D. Moreover, the alterations in cellular energy requirements associated with insulin resistance could affect many metabolic changes in the body that eventually result in pathology and could serve as a unified mechanism that also functions in many metabolic diseases. However, these issues have not been comprehensively described. Therefore, here, we discuss the basic molecular mechanisms underlying the pathological processes associated with the development of insulin resistance; the major inducers, regulators, and metabolic consequences of insulin resistance; and instruments for controlling insulin resistance as a new approach to therapy.

The Effects of Diabetes and Diabetic Medications on Bone Health

The incidence and prevalence of diabetes continues to increase, and proper understanding of the adverse effects on bone metabolism is important. This review attempts to discuss the pathophysiology of the effects of diabetes and diabetic medications on bone metabolism and bone health. In addition, this review will address the mechanisms resulting in increased fracture risk and delayed bone healing to better treat and manage diabetic patients in the orthopedic clinical setting.

[there any association of metabolic disturbances with joint destruction and pain?]

Osteoarthritis and type 2 diabetes mellitus represent two the most common chronic diseases. They possess many shared epidemiologic traits, have common risk factors, and embody heterogeneous multifactorial pathologies, which develop due to interaction of genetic an environmental factors. In addition, these diseases are often occurring in the same patient. In spite of the differences in clinical manifestation both diseases have similar disturbances of cellular metabolism, primarily associated with ATP production and utilization. The review discusses molecular mechanisms determining pathophysiological processes associated with glucose and lipid metabolism as well as the means aiming to alleviate the disturbances of energy metabolism as a new a therapeutic approach.

AdipoRon promotes diabetic fracture repair through endochondral ossification-based bone repair by enhancing survival and differentiation of chondrocytes

Diabetic bone defects may exhibit impaired endochondral ossification (ECO) leading to delayed bone repair. AdipoRon, a receptor agonist of adiponectin polymers, can ameliorate diabetes and related complications, as well as overcome the disadvantages of the unstable structure of artificial adiponectin polymers. Here, the effects of AdipoRon on the survival and differentiation of chondrocytes in a diabetic environment were explored focusing on related mechanisms in gene and protein levels. In vivo, AdipoRon was applied to diet-induced-obesity (DIO) mice, a model of obesity and type 2 diabetes, with femoral fracture. Sequential histological evaluations and micro-CT were examined for further verification. We found that AdipoRon could ameliorate cell viability, apoptosis, and reactive oxygen species (ROS) production and promote mRNA expression of chondrogenic markers and cartilaginous matrix production of ATDC5 cells in high glucose medium via activating ERK1/2 pathway. Additionally, DIO mice with intragastric AdipoRon administration had more neocartilage and accelerated new bone formation. These data suggest that AdipoRon could stimulate bone regeneration via ECO in diabetes.

Uniform-sized insulin-loaded PLGA microspheres for improved early-stage peri-implant bone regeneration

Poor initial stability at the first four weeks after surgery is becoming the major causes for metal implant failure. Previous attempts neglected the control release of insulin for the bone regeneration among nondiabetic subjects. The major reason may lie in the adverse effects, such as attenuated bone formation, hypoglycemia or hyperinsulinemia, that caused by the excessive insulin. Thus, spatiotemporal release of insulin may serve as the promising strategy. To address this, through solvent extraction (EMS), solvent evaporation (SMS) and cosolvent methods (CMS), we prepared three types of PLGA microspheres with various internal structures, but similar size distribution. The effects of the preparation methods on the properties of the microspheres, such as their release behavior, degradation of molecular weight, and structural evolution, were investigated. Human bone marrow mesenchymal stromal cells (BMSCs) and rabbit implant models were used to test the bioactivity of the microspheres in vitro and in vivo, respectively. The result demonstrated that these three preparation methods did not influence the polymer degradation but instead affected the internal structural evolution, which plays a crucial role in the release behavior, osteogenesis and peri-implant bone regeneration. Compared with EMS and CMS microspheres, SMS microspheres exhibited a relatively steady release rate in the first four weeks, which evidently stimulated the osteogenic differentiation of the stem cells and peri-implant bone regeneration. Meanwhile, SMS microspheres significantly enhanced the stability of the implant at Week 4, which is promising to reduce early failure rate of the implant without inducing adverse effects on the serum biochemical indices.

Review of Animal Models of Comorbidities in Fracture-Healing Research

There is clinical evidence that patient-specific comorbidities like osteoporosis, concomitant tissue injury, and ischemia may strongly interfere with bone regeneration. However, underlying mechanisms are still unclear. To study these mechanisms in detail, appropriate animal models are needed. For decades, bone healing has been studied in large animals, including dogs, rabbits, pigs, or sheep. However, large animal models display a limited ability to study molecular pathways and cellular functions. Therefore in recent years, mice and rats have become increasingly popular as a model organism for fracture healing research due to the availability of molecular analysis tools and transgenic models. Both large and small animals can be used to study comorbidities and risk factors, modelling the human clinical situation. However, attention has to be paid when choosing an appropriate model due to species differences between large animals, rodents, and humans. This review focuses on large and small animal models for the common comorbidities ischemic injury/reduced vascularization, osteoporosis, and polytrauma, and critically discusses the translational and molecular aspects of these models. Here, we review material which was presented at the workshop "Animal Models of Comorbidities in Fracture Healing Research" at the 2019 ORS Annual Meeting in Austin Texas. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2491-2498, 2019.

Inhibition of microRNA-222 up-regulates TIMP3 to promotes osteogenic differentiation of MSCs from fracture rats with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is the most common diabetes and has numerous complications. Recent studies demonstrated that T2DM compromises bone fracture healing in which miR-222 might be involved. Furthermore, tissue inhibitor of metalloproteinase 3 (TIMP-3) that is the target of miR-222 accelerates fracture healing. Therefore, we assume that miR-222 could inhibit TIMP-3 expression. Eight-week-old rats were operated femoral fracture or sham, following the injection of streptozotocin (STZ) to induce diabetes one week later in fractured rats, and then, new generated tissues were collected for measuring the expression of miR-222 and TIMP-3. Rat mesenchymal stem cells (MSCs) were isolated and treated with miR-222 mimic or inhibitor to analyse osteogenic differentiation. MiR-222 was increased in fractured rats and further induced in diabetic rats. In contrast, TIMP-3 was reduced in fractured and further down-regulated in diabetic rats. Luciferase report assay indicated miR-222 directly binds and mediated TIMP-3. Furthermore, osteogenic differentiation was suppressed by miR-222 mimic and promoted by miR-222 inhibitor. miR-222 is a key regulator that is promoted in STZ-induced diabetic rats, and it binds to TIMP3 to reduce TIMP-3 expression and suppressed MSCs' differentiation.

Impact of Diabetes Mellitus on Bone Health

Long-term exposure to a diabetic environment leads to changes in bone metabolism and impaired bone micro-architecture through a variety of mechanisms on molecular and structural levels. These changes predispose the bone to an increased fracture risk and impaired osseus healing. In a clinical practice, adequate control of diabetes mellitus is essential for preventing detrimental effects on bone health. Alternative fracture risk assessment tools may be needed to accurately determine fracture risk in patients living with diabetes mellitus. Currently, there is no conclusive model explaining the mechanism of action of diabetes mellitus on bone health, particularly in view of progenitor cells. In this review, the best available literature on the impact of diabetes mellitus on bone health in vitro and in vivo is summarised with an emphasis on future translational research opportunities in this field.

Are serum levels of ADAMTS5, TAS and TOS at 24-28 gestational weeks associated with adverse perinatal outcomes in gestational diabetic women?

We aimed to determine the role of placental A Disintegrin and Metalloproteinase with thrombospondin motifs 5 (ADAMTS5), and maternal serum ADAMTS5, total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) levels at 24-28th gestational weeks in GDM. This study included 57 patients, who had been diagnosed as having GDM at their 24-28th gestational week, and 29 controls. The maternal blood samples were collected at the 24-28th gestational week and ADAMTS5 was studied with the enzyme-linked immunosorbent assay (ELISA) method, whereas an automated colorimetric method was used to study TAS, TOS, and OSI. The level of ADAMTS5 in maternal serum of patients with GDM were significantly lower than the controls (p = .017); whereas TOS and OSI levels were significantly higher (p = .003 and p = .008). Multivariable logistic regression analysis revealed ADAMTS5 and TOS levels were independently associated with adverse perinatal outcomes (p = .004 and p = .018). We found that serum ADAMTS5 levels decreased and TOS level increased in GDM pregnant at 24-28th gestational weeks. In addition, we found that increased levels of serum ADAMTS5 and decreased TOS levels at 24-28th weeks were associated with adverse perinatal outcomes independent of the mode of treatment in GDM.Impact statementWhat is already known on this subject? Gestational diabetes mellitus (GDM) is one of the most common medical complications of pregnancy. The insulin resistance, which starts at the 24-28th gestational weeks, increases during gestation. GDM increases maternal complications like preeclampsia, cesarean rate, cardiovascular disease, obesity, and diabetes after pregnancy; and neonatal complications like macrosomia, hypoglycemia, hyperbilirubinemia, delivery trauma, shoulder dystocia, and adult-onset obesity, and diabetes.What the results of this study add? A significant relationship between ADAMTS5, TOS levels and adverse perinatal outcome. insulin resistance and was observed.What the implications are of these findings for clinical practice and/or further research? Based on this finding, we concluded that increased levels of oxidative stress and decreased ADAMTS5 levels are associated with GDM and predictive for adverse perinatal outcomes. The results of the present study were consistent with the previous reports and indicated that increased oxidative stress in GDM patients are related to adverse perinatal outcomes.

Diabetic hip arthropathy is associated with a higher prevalence of femoral head chondromalacia: a case-controlled study

INTRODUCTION

No previous studies have characterised hip joint disease in diabetic patients undergoing hip arthroscopy. The purpose of our study was to evaluate intra-articular hip pathology and surgical variables in patients with diabetes compared to matched, non-diabetic controls. We hypothesised that diabetic patients would demonstrate a higher prevalence and severity of hip chondral pathology.

METHODS

We retrospectively reviewed 795 consecutive hip arthroscopies performed by a single surgeon between 2010 and 2015. Patients ⩾18 years of age without a history of diabetes served as controls and were matched based on age, sex, body mass index, duration of symptoms, and operative side. Clinical symptoms, preoperative physical examination, and radiologic and intraoperative findings were assessed. The primary outcomes were the acetabular and femoral head chondromalacia index (CMI), calculated as the product of the Outerbridge chondromalacia grade and surface area (mm²*severity).

RESULTS

15 diabetic patients were matched to 137 non-diabetic controls. Diabetic patients demonstrated a higher prevalence of femoral head chondromalacia compared to controls both on magnetic resonance imaging (45.5% vs. 7.5%, p = 0.002) and during arthroscopy (100% vs. 75.9%, p = 0.042). Femoral head chondromalacia in diabetic patients had higher Outerbridge grade (2.4 vs. 2.0, p = 0.030) but similar CMI (513.0 vs. 416.4, p = 0.298) compared to controls.

DISCUSSION

Femoral head chondral pathology was more prevalent and of higher severity grade in diabetic patients. The prevalence, size, and severity of acetabular chondral disease were similar between diabetic and non-diabetic patients. Multivariate analysis demonstrated that diabetic status was independently associated with the presence of femoral head chondromalacia.

Progranulin promotes diabetic fracture healing in mice with type 1 diabetes

Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by insulin deficiency, and patients with diabetes have an increased risk of bone fracture and significantly impaired fracture healing. Proinflammatory cytokine tumor necrosis factor-alpha is significantly upregulated in diabetic fractures and is believed to underlie delayed fracture healing commonly observed in diabetes. Our previous genetic screen for the binding partners of progranulin (PGRN), a growth factor-like molecule that induces chondrogenesis, led to the identification of tumor necrosis factor receptors (TNFRs) as the PGRN-binding receptors. In this study, we employed several in vivo models to ascertain whether PGRN has therapeutic effects in diabetic fracture healing. Here, we report that deletion of PGRN significantly delayed bone fracture healing and aggravated inflammation in the fracture models of mice with T1DM. In contrast, recombinant PGRN effectively promoted diabetic fracture healing by inhibiting inflammation and enhancing chondrogenesis. In addition, both TNFR1 proinflammatory and TNFR2 anti-inflammatory signaling pathways are involved in PGRN-stimulated diabetic fracture healing. Collectively, these findings illuminate a novel understanding concerning the role of PGRN in diabetic fracture healing and may have an application in the development of novel therapeutic intervention strategies for diabetic and other types of impaired fracture healing.

Deletion of FOXO1 in chondrocytes rescues the effect of diabetes on mechanical strength in fracture healing

Diabetes increases the risk of fracture, impairs fracture healing and causes rapid loss of the fracture callus cartilage, which was linked to increased FOXO1 expression in chondrocytes. We recently demonstrated that deletion of FOXO1 in chondrocytes blocked the premature removal of cartilage associated with endochondral bone formation during fracture healing. However, the ultimate impact of this deletion on mechanical strength was not investigated and remains unknown. Closed fractures were induced in Col2α1Cre⁺.FOXO1^L/L mice with lineage specific deletion of FOXO1 in chondrocytes compared to littermate controls. Type 1 diabetes was induced by multiple low dose streptozotocin treatment. Thirty-five days after fracture micro CT analysis showed that diabetes significantly reduced callus volume and bone volume (P < 0.05), both which were reversed by FOXO1 deletion in chondrocytes. Diabetes significantly reduced mechanical strength measured by maximum torque, stiffness, modulus of rigidity and toughness and FOXO1 deletion in diabetic mice rescued each parameter (P < 0.05). Diabetes also reduced both bone volume and mechanical strength in non-fractured femurs. However, FOXO1 deletion did not affect bone volume or strength in non-fractured bone. These results point to the important effect that diabetes has on chondrocytes and show for the first time that the premature removal of cartilage induced by FOXO1 in chondrocytes has a significant impact on the mechanical strength of the healing bone.

Chondrocytes Promote Vascularization in Fracture Healing Through a FOXO1-Dependent Mechanism

Chondrocytes play an essential role in fracture healing by producing cartilage, which forms an anlage for endochondral ossification that stabilizes the healing fracture callus. More recently it has been appreciated that chondrocytes have the capacity to produce factors that may affect the healing process. We examined the role of chondrocytes in angiogenesis during fracture healing and the role of the transcription factor forkhead box-O 1 (FOXO1), which upregulates wound healing in soft tissue. Closed fractures were induced in experimental mice with lineage-specific FOXO1 deletion by Cre recombinase under the control of a collagen-2α1 promoter element (Col2α1Cre+ FOXO1L/L ) and Cre recombinase negative control littermates containing flanking loxP sites (Col2α1Cre- FOXO1L/L ). Experimental mice had significantly reduced CD31+ new vessel formation. Deletion of FOXO1 in chondrocytes in vivo suppressed the expression of vascular endothelial growth factor-A (VEGFA) at both the protein and mRNA levels. Overexpression of FOXO1 in chondrocytes in vitro increased VEGFA mRNA levels and VEGFA transcriptional activity whereas silencing FOXO1 reduced it. Moreover, FOXO1 interacted directly with the VEGFA promoter and a deacetylated FOXO1 mutant enhanced VEGFA expression whereas an acetylated FOXO1 mutant did not. Lastly, FOXO1 knockdown by siRNA significantly reduced the capacity of chondrocytes to stimulate microvascular endothelial cell tube formation in vitro. The results indicate that chondrocytes play a key role in angiogenesis which is FOXO1 dependent and that FOXO1 in chondrocytes regulates a potent angiogenic factor, VEGFA. These studies provide new insight into fracture healing given the important role of vessel formation in the fracture repair process. © 2018 American Society for Bone and Mineral Research.

Risk Factors Associated with 30-Day Mortality After Open Reduction and Internal Fixation of Vertebral Fractures

OBJECTIVE

Few studies have examined the outcomes of open reduction and internal fixation of vertebral fractures. The purpose of this study was to determine patient-related and surgery-related risk factors associated with 30-day postoperative mortality after open reduction and internal fixation (ORIF) of cervical, thoracic, and lumbar vertebral fractures.

METHODS

This was a retrospective cohort study of data from the 2010-2014 ACS-NSQIP database. Adult patients who underwent ORIF of vertebral fractures in the cervical, thoracic, or lumbar spine were included. Patients were divided into 2 groups on the basis of the occurrence of 30-day postoperative mortality. A univariate analysis was performed to compare baseline patient characteristics, comorbidities, operative variables, and 30-day postoperative complications between the mortality and nonmortality groups. A subsequent multivariate regression analysis adjusting for patient and operative factors was then performed to identify independent risk factors for 30-day mortality.

RESULTS

A total of 900 patients who underwent vertebral ORIF were included. The overall 30-day postoperative mortality rate was 1.56%. The mortality group had a higher incidence of pneumonia, pulmonary complications, cardiac complications, blood transfusion, sepsis, and prolonged hospitalization. Multivariate regression analysis identified pulmonary comorbidity and diabetes as independent predictors of 30-day mortality following ORIF of vertebral fractures.

CONCLUSIONS

Pulmonary comorbidity and diabetes were found to be independent risk factors for 30-day mortality after ORIF of vertebral fractures. Recognizing these risk factors is important in preoperative risk stratification, perioperative care, and patient counseling.

Bone callus formation is highly disrupted by dietary restriction in growing rats sustaining a femoral fracture1

PURPOSE

To evaluate the effects of food restriction on fracture healing in growing rats.

METHODS

Sixty-eight male Wistar rats were assigned to two groups: (1) Control and (2) Dietary restriction. After weaning the dietary restricted animals were fed ad libitum for 42 days with 50% of the standard chow ingested by the control group. Subsequently, the animals underwent bone fracture at the diaphysis of the right femur, followed by surgical stabilization of bone fragments. On days 14 and 28 post-fracture, the rats were euthanized, and the fractured femurs were dissected, the callus was analyzed by dual-energy X-ray absorptiometry, micro-computed tomography, histomorphometry, mechanical tests, and gene expression.

RESULTS

Dietary restriction decreased body mass gain and resulted in several phenotypic changes at the bone callus (a delay in cell proliferation and differentiation, lower rate of newly formed bone and collagen deposition, reductions in bone callus density and size, decrease in tridimensional callus volume, deterioration in microstructure, and reduction in bone callus strength), together with the downregulated expression of osteoblast-related genes.

CONCLUSION

Dietary restriction had detrimental effects on osseous healing, with a healing delay and a lower quality of bone callus formation.

Leptin-deficient mice have altered three-dimensional growth plate histomorphometry

BACKGROUND

Leptin is an adipokine that regulates energy homeostasis and is also needed for normal bone growth and maintenance. Mutation in the lep gene, which characterizes the ob/ob mouse model, results in the development of obesity and type 2 diabetes mellitus, as well as reduced limb bone length and increased fracture risk. However, the relationship between limb bone length and growth plate cartilage structure in obese diabetic adolescents is incompletely understood. Here, we tested the hypothesis that leptin deficiency affects the microstructure of growth plate cartilage in juvenile ob/ob mice.

METHODS

Tibial growth plate cartilage structure was compared between lean and obese, leptin-deficient (ob/ob) female mice aged 10 weeks. We used confocal laser scanning microscopy to assess 3D histological differences in Z stacks of growth plate cartilage at 0.2 µm intervals, 80-100 µm in depth. Histomorphometric comparisons were made between juvenile lean and ob/ob mice.

RESULTS

We found obese mice have significantly reduced tibial length and growth plate height in comparison with lean mice (P < 0.05). Obese mice also have fewer chondrocyte columns in growth plate cartilage with reduced chondrocyte cell volumes relative to lean mice (P < 0.05).

CONCLUSIONS

These data help explicate the relationship between growth plate cartilage structure and bone health in obese diabetic juvenile mice. Our findings suggest obesity and diabetes may adversely affect growth plate cartilage structure.

Scaffolds of bioactive glass-ceramic (Biosilicate®) and bone healing: A biological evaluation in an experimental model of tibial bone defect in rats

This study aimed to investigate the in vivo tissue response of the Biosilicate® scaffolds in a model of tibial bone defect. Sixty male Wistar rats were distributed into bone defect control group (CG) and Biosilicate® scaffold group (BG).  Animals were euthanized 15, 30 and 45 days post-surgery. Stereomicroscopy, scanning electron microscopy, histopathological, immunohistochemistry and biomechanical analysis were used. Scaffolds had a total porosity of 44%, macroporosity of 15% with pore diameter of 230 μm. Higher amount of newly formed bone was observed on days 30 and 45 in BG. Immunohistochemistry analysis showed that the COX-2 expression was significantly higher on days 15 and 30 in BG compared with the CG. RUNX-2 immunoexpression was significantly higher in BG on days 15 and 45. No statistically significant difference was observed in RANKL immunoexpression in all experimental groups. BMP-9 immunoexpression was significantly upregulated in the BG on day 45. Biomechanical analysis showed a decrease in the biomechanical properties of the bone callus on days 30 and 45. The implantation of the Biosilicate® scaffolds was effective in stimulating newly bone formation and produced an increased immunoexpression of markers related to the bone repair.

Strontium Ranelate Combined with Insulin Is as Beneficial as Insulin Alone in Treatment of Fracture Healing in Ovariectomized Diabetic Rats

Background

Type 2 diabetes mellitus (T2DM) and estrogen deficiency both predispose fracture patients to increased risk of delayed union or nonunion. The present study investigated the effects of strontium ranelate (SR) on fracture healing in ovariectomized (OVX) diabetic rats.

Material/Methods

A mid-shaft fracture was established in female normal control (CF), diabetic (DF), and OVX diabetic (DOF) rats. Treated DOF rats received either insulin alone (DOFI) or combined with SR (DOFIS). All rats were euthanized at 2 or 3 weeks after fracture. Fracture healing was evaluated using radiological, histological, immunohistochemical, and micro-computed tomography analyses.

Results

At 3 weeks after fracture, radiological and histological evaluations demonstrated delayed fracture healing in the DF group compared with the CF group, which was exacerbated by OVX, as indicated by the significantly lower X-ray score, BMD, BV/TV, and Md.Ar/Ps.Cl.Ar, and the markedly decreased OCN and Col I expression in the DOF group. All these changes were prevented by insulin alone or combined with SR treatment. In comparison with the DOFI group, DOFIS rats displayed markedly higher OCN expression at 2 weeks after fracture and Col I expression at 2 and 3 weeks after fracture.

Conclusions

These results demonstrated delayed fracture healing with preexisting estrogen deficiency and T2DM. While insulin alone and combined with SR were both effective in promoting bone fracture healing in this model, their combined treatment showed significant improvement in promoting osteogenic marker expression, but not of the radiological appearance, compared with insulin alone.

A high-fat diet can affect bone healing in growing rats

A high-fat diet (HFD) can have a negative effect on bone quality in young and old people. Although bone healing in children is normally efficient, there is no evidence that children who have a diet rich in fat have compromised bone fracture regeneration compared with children with recommended dietary fat levels. The purpose of the present study was to evaluate the effects of an HFD on bone healing in growing female rats. Twenty-six postweaning female Wistar rats were divided into two groups (13 animals per group): a standard diet (SD) group and an HFD (with 60% of energy from fat) group. The rats received the assigned diets for 5 weeks, and in the third week they were submitted to an osteotomy procedure of the left tibia. Body mass and feed intake were recorded during the experiment. One day before euthanasia, an insulin tolerance test was performed. After euthanasia, the tibiae were removed and analyzed by densitometry, mechanical testing, histomorphometry, stereology and immunohistochemistry. An HFD caused an adaptive response to maintain energetic balance by decreasing feed intake and causing insulin insensitivity. There was no change in bone mineral density, collagen amount and immunostaining for bone formation, but maximal load and stiffness were decreased in the HFD group. In addition, bone volume had a tendency to be higher in the SD group than in the HFD group. Compared with rats receiving an SD, growing rats receiving an HFD for 5 weeks had similar bone mineral density but altered mechanical properties at the osteotomy defect site.

The burden of inpatient care for diabetic and non-diabetic patients with osteoporotic hip fractures-does it differ? An analysis of patients recruited into a fracture liaison service in Southeast Asia

Hospital care and mortality of diabetic and non-diabetic osteoporotic Asian patients undergoing hip fracture surgery were explored with no difference in length of hospitalization, incidence of post-operative complications, or mortality between diabetics and non-diabetics seen. Time to operation correlated with post-operative complications occurrence and therefore surgery should be expeditiously done.

INTRODUCTION

Whether burden of inpatient care, problems after admission, and mortality rates differ between diabetics and non-diabetics undergoing surgery for osteoporotic hip fractures has not been explored in Asian populations.

METHOD

Three hundred eighty-nine multi-ethnic diabetic and non-diabetic patients recruited into a FLS at a large Asian hospital with new osteoporotic hip fractures requiring operative repair were analyzed.

RESULTS

87.9% were Chinese, 6.4% Malay, and 3.6% Indians. BMI and age did not significantly differ between diabetics and non-diabetics. Median (IQR) length of hospitalization (LOHS) in days was 12 (9, 17) in diabetics and 11 (8, 14) in non-diabetics (p = 0.011). Median time from admission to operation (TTO) was 3 (2, 5) in diabetics versus 2 (1, 4.5) in the non-diabetics (p = 0.003). Occurrence of aggregate post-operative complications did not differ between diabetics and non-diabetics. No in-hospital mortalities occurred in either group. Thirty-day and 1-year mortality rates did not differ between the two groups. One-year mortality was 2.8% in the entire cohort. On multivariate regression analysis adjusted for age and race, only TTO (β; 1.8, 95% CI 1.5-2.0, p < 0.001) and occurrence of post-operative complications (β; 6.3, 95% CI 3.7-7.9, p < 0.001) correlated with LOHS. TTO and age-adjusted Charlson's Comorbidity Index (CCI) correlated significantly with the development of post-operative complications.

CONCLUSIONS

Diabetes was not independently associated with LOHS in patients undergoing hip fracture surgery. Aggregate post-operative complications did not differ between diabetics and non-diabetics. TTO and occurrence of post-operative complications significantly affected LOHS. TTO correlated with post-complications development. Surgery should be expeditiously done in both diabetics and non-diabetics to avoid the development of post-operative complications and to prevent prolonged hospital stay.

Effects of local vanadium delivery on diabetic fracture healing

This study evaluated the effect of local vanadyl acetylacetonate (VAC), an insulin mimetic agent, upon the early and late parameters of fracture healing in rats using a standard femur fracture model. Mechanical testing, and radiographic scoring were performed, as well as histomorphometry, including percent bone, percent cartilage, and osteoclast numbers. Fractures treated with local 1.5 mg/kg VAC possessed significantly increased mechanical properties compared to controls at 6 weeks post-fracture, including increased torque to failure (15%; p = 0.046), shear modulus (89%; p = 0.043), and shear stress (81%; p = 0.009). The radiographic scoring analysis showed increased cortical bridging at 4 weeks and 6 weeks (119%; p = 0.036 and 209%; p = 0.002) in 1.5 mg/kg VAC treated groups. Histomorphometry of the fracture callus at days 10 and 14 showed increased percent cartilage (121%; p = 0.009 and 45%; p = 0.035) and percent mineralized tissue (66%; p = 0.035 and 58%; p = 0.006) with local VAC treated groups compared to control. Additionally, fewer osteoclasts were observed in the local VAC treated animals as compared to controls at day 14 (0.45% ± 0.29% vs. 0.83% ± 0.36% of callus area; p = 0.032). The results suggest local administration of VAC acts to modulate osteoclast activity and increase percentage of early callus cartilage, ultimately enhancing mechanical properties comparably to non-diabetic animals treated with local VAC. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2174-2180, 2017.

Parathyroid hormone (1-34) promotes fracture healing in ovariectomized rats with type 2 diabetes mellitus

Ovariectomized (OVX) rats with type 2 diabetes mellitus (T2DM) with femur fracture received vehicle, insulin, or insulin plus parathyroid hormone (PTH) treatment for 2 and 3 weeks. Radiography, histomorphometry, histology, and immunohistochemistry in callus were evaluated.

INTRODUCTION

Reports about effects of PTH plus insulin on callus formation of osteoporotic fracture with T2DM were limited. This study was designed to investigate the effects of the combination of PTH and insulin on fracture healing in OVX rats with T2DM.

METHODS

Two-month-old female rats were randomly divided into five groups: normal fracture (F), OVX fracture (OF), T2DM + OVX fracture (DOF), insulin-treated (2-4 u/daylight, 4-6 u/night, DOFI), and treated with insulin and PTH (50 μg/kg/day, 5 days/week, DOFIP). A closed mid-shaft fracture was established in the right femurs of all rats after 6 weeks of OVX. Rats were euthanized at 2 and 3 weeks post-fracture according to the time schedule, respectively.

RESULTS

The administration of insulin alone or insulin combined with PTH significantly increased mineralized bone volume fraction (BV/TV) and connectivity density (Conn.D) compared with those of the DOF group at 3 weeks post-fracture and also increased cartilaginous callus area ratio in the DOFI and DOFIP groups at 2 weeks and bony callus area ratio in the DOFIP groups at both the 2 and 3 weeks post-fracture.

CONCLUSIONS

OVX rats with T2DM exhibited a marked delay in the fracture healing process; insulin treatment ameliorated these effects, and the healing process was enhanced following treatment with a combination of insulin and PTH.

Transplantation of human skeletal muscle-derived progenitor cells ameliorates knee osteoarthritis in streptozotocin-induced diabetic mice

The epidemiological and experimental evidence suggests that diabetes can be an independent risk factor for osteoarthritis. The osteoarthritis-like cartilage damage has been shown in streptozotocin-induced diabetic mice. The therapeutic effects of human skeletal muscle-derived progenitor cells (HSMPCs) on diabetic osteoarthritis still remain unclear. Here, we investigated the therapeutic potential of HSMPCs on diabetic knee osteoarthritis. The in vitro chondrogenic ability of HSMPCs was determined by pellet culture assay. Male mice were used to develop the model of streptozotocin-induced type 1 diabetes and its related osteoarthritis. HSMPCs were injected intra-articularly to rescue osteoarthritis. Protein expressions of advanced glycation end-products, cyclooxygenase-2, and type-2 collagen in tissues were determined by immunohistochemistry. The pellet culture assay showed that HSMPCs cultured in differentiation medium for chondrogenesis significantly produced larger pellets with an overproduction of extracellular matrix than in growth medium. In in vivo experiments, intra-articular injection of HSMPCs for 4 weeks significantly prevented the progression of degenerative changes in the cartilage of streptozotocin-induced diabetic mice, including an obvious increase of total articular cartilage thickness and a decrease of fibrous cartilage thickness. HSMPCs transplantation also exerted the decline in advanced glycation end-products and cyclooxygenase-2 protein expression, but increased the type-2 collagen protein expression in streptozotocin-induced osteoarthritic cartilages. Moreover, HSMPCs transplantation also inhibited the increased serum interleukin-6 and matrix metalloproteinase-3 levels in diabetic mice. These results demonstrated for the first time that HSMPCs transplantation ameliorates cartilage degeneration in diabetes-related osteoarthritis mice. These findings suggest that HSMPCs transplantation may apply as a potential therapeutic use of diabetes-related osteoarthritis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1886-1893, 2017.

TNFα contributes to diabetes impaired angiogenesis in fracture healing

Diabetes increases the likelihood of fracture, interferes with fracture healing and impairs angiogenesis. The latter may be significant due to the critical nature of angiogenesis in fracture healing. Although it is known that diabetes interferes with angiogenesis the mechanisms remain poorly defined. We examined fracture healing in normoglycemic and streptozotocin-induced diabetic mice and quantified the degree of angiogenesis with antibodies to three different vascular markers, CD34, CD31 and Factor VIII. The role of diabetes-enhanced inflammation was investigated by treatment of the TNFα-specific inhibitor, pegsunercept starting 10days after induction of fractures. Diabetes decreased both angiogenesis and VEGFA expression by chondrocytes. The reduced angiogenesis and VEGFA expression in diabetic fractures was rescued by specific inhibition of TNF in vivo. In addition, the TNF inhibitor rescued the negative effect of diabetes on endothelial cell proliferation and endothelial cell apoptosis. The effect of TNFα in vitro was enhanced by high glucose and an advanced glycation endproduct to impair microvascular endothelial cell proliferation and tube formation and to stimulate apoptosis. The effect of TNF, high glucose and an AGE was mediated by the transcription factor FOXO1, which increased expression of p21 and caspase-3. These studies indicate that inflammation plays a major role in diabetes-impaired angiogenesis in endochondral bone formation through its effect on microvascular endothelial cells and FOXO1.

American College of Foot and Ankle Surgeons® Clinical Consensus Statement: Perioperative Management

A wide range of factors contribute to the complexity of the management plan for an individual patient, and it is the surgeon's responsibility to consider the clinical variables and to guide the patient through the perioperative period. In an effort to address a number of important variables, the American College of Foot and Ankle Surgeons convened a panel of experts to derive a clinical consensus statement to address selected issues associated with the perioperative management of foot and ankle surgical patients.