Objectives. This study aims to evaluate if micro-CT can work as a method for the 3D assessment and analysis of cancellous bone by comparing micro-CT with undecalcified histological sections in OVX rats. Methods. The mandible and tibia of sham, ovariectomised (OVX) and zoledronate-injected ovariectomised (OVX-ZOL) rats were assessed morphometrically. Specimens were scanned by micro-CT. Undecalcified histological sections were manufactured from the specimen scanned by micro-CT and stained with haematoxylin and eosin. Bivariate linear regressions and one-way analysis of variance were undertaken for statistics using SPSS 16.0.1 software. Results. There were highly significant correlations between undecalcified histological sections and micro-CT for all parameters (bone volume density (BV/TV), bone surface density (BS/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp))in the mandible and tibia. Bone histomorphometric parameters analysed by both methods exhibited significant differences among sham, OVX, and OVX-ZOL groups. There were significant correlations between mandible and tibia in BV/TV, BS/BV, and Tb.Sp. Conclusions. Micro-CT is a complementary tool to histological sections in basic research that could improve our understanding of bone histomorphometry. The mandible can be used as an effective site to assess bone morphometry of OVX or metabolic bone disease rat models. Cite this article: H. Liu, W. Li, Y. S. Liu, Y. S. Zhou. Bone micro-architectural analysis of mandible and tibia in ovariectomised rats: A quantitative structural comparison between undecalcified histological sections and micro-CT. Bone Joint Res 2016;5:253–262

Objectives

Little is known about tissue changes underlying bone marrow lesions (BMLs) in non-weight-bearing joints with osteoarthritis (OA). Our aim was to characterize BMLs in OA of the hand using dynamic histomorphometry. We therefore quantified bone turnover and angiogenesis in subchondral bone at the base of the thumb, and compared the findings with control bone from hip OA.

Fragility fractures are skeletal complications associated with type 2 diabetes (T2D) causing disability, hospitalization, impaired quality of life, and increased mortality. Increased circulating sclerostin and accumulation of advanced glycation end-products (AGEs) are two potential mechanisms underlying low bone turnover and increased fracture risk. We have recently shown that T2D affects the expression of genes controlling bone formation (SOST and RUNX2) and that accumulation of AGEs is associated with impaired bone formation in T2D. We hypothesized that Wnt/B- catenin target genes are down-regulated in bone of T2D subjects as a consequence of decreased SOST and AGEs accumulation. To this end, we studied gene expression in extracts of bone samples obtained from femoral heads of 14 subjects with relatively well-controlled T2D (HbA1c 6.5±1.7%) and 21 control, non-diabetic postmenopausal women (age >65 years) undergoing hip replacement. There were no differences in age (73.2± .8 vs. 75.2±8.5 years) or BMI (27.7±5.6 vs. 29.9±5.4 kg/m2) between control and T2D groups, respectively. Expression of LEF1 mRNA was significantly lower in T2D compared to non-diabetic subjects (p=0.002), while DKK1 was not different between groups (p=0.108). Correlation analysis showed that DKK1 (r2=0.038; p=0.043) and HbA1c (r2=0.503; p=0.048) increased with age in T2D. COL1A1 mRNA trended lower in T2D compared to controls (p=0.056). Bone volume (9,333 ± 1,443 vs. 15,53 ± 2,442 mm2; p=0.048), mineralized volume (9,278 ± 1,418 vs. 15,45 ± 2,444 mm. 2. ; p=0.048) and BV/TV (0,2125 ± 0,03114 vs. 0,3719 ± 0,03196 %; p=0.002) measured by bone histomorphometry were lower in T2D compared to controls. Our data show that even in patients with relatively good glycemic control, T2D decreases expression of Wnt/B-catenin target genes andCOL1A1, associated with decreased bone density. These results may help understand the mechanisms underlying bone fragility in T2D

Summary. Osteoporosis reduces particle-induced osteolysis in rat model. Introduction. Wear particle induced osteolysis is considered to be a vital factor that reduces the life span of joint prosthesis. Osteoporosis is not rare in patients with indication for arthroplasty. However, the influence of osteoporosis on wear particles induced osteolysis is not clear. This study is aimed to explore on this issue by using animal model. Methods. 42 female Sprague-Dawley (SD) rats aged 6 months were randomly divided into 3 groups: A, B and C group. Group A and B contained 18 rats each, and group C contained 6 rats. The rats in group A underwent bilateral ovariectomy. Group B was normal control, and group C was sham control. After 3 months, 6 rats in group A, 6 rats in group B and all the rats of group C were sacrificed. Bone mineral density (BMD), μCT and bone histomorphometry were conducted. The rest of rats in group A were randomly divided into 2 groups: group A1 and group A2, and so were the rats in group B. 5mg titanium particles were implanted onto the calvaria of groups A1 and B1, and isometric PBS solution were injected to group A2 and B2. Calvaria were harvested after 14 days. Calvaria were analyzed by μCT and histomorphometry to measure the osteolysis area of calvarial sagittal suture. Results. Compared with B and C group, BMD and bone histomorphometry index of group A was significantly reduced (P<0.05), and tibial trabeculae of group A was slimmer. Area of calvarial sagittal suture osteolysis were 0.262±0.009mm. 2. , 0.130±0.013mm. 2. , 0.307±0.013mm. 2. and 0.178±0.011mm. 2. in A1, A2, B1and B2 groups, respectively. There was significant difference among the groups. Conclusions. Osteoporosis may reduce particle-induced osteolysis in rat model

Aims

Osteoporosis is characterized by decreased trabecular bone volume, and microarchitectural deterioration in the medullary cavity. Interleukin-19 (IL-19), a member of the IL-10 family, is an anti-inflammatory cytokine produced primarily by macrophages. The aim of our study was to investigate the effect of IL-19 on osteoporosis.

Structural bone allografts are a viable option in reconstructing massive bone defects in patients following musculoskeletal (MSK) tumour resection and revision hip/knee replacements. To decrease infection risk, bone allografts are often sterilised with gamma-irradiation, which consequently degrades the bone collagen connectivity and makes the bone brittle. Clinically, irradiated bone allografts fracture at rates twice that of fresh non-irradiated allografts. Our lab has developed a method that protects the bone collagen connectivity through ribose pre-treatment while still undergoing gamma-irradiation. Biomechanical testing of bone pretreated with our method provided 60–70% protection of toughness and 100% protection of strength otherwise lost with conventional irradiation. This study aimed to determine if the ribose-treated bone allografts are biocompatible with host bone. The New Zealand White rabbit (NZWr) radius segmental defect model was used, in which 15-mm critically-sized defects were created. Bone allografts were first harvested from the radial diaphysis of donor female NZWr, and treated to create 3 graft types: C=untreated controls, I=conventionally-irradiated (33 kGy), R=our ribose pretreated + irradiation method. Recipient female NZWr (n=24) were then evenly randomised into the 3 graft groups. Allografts were surgically fixed with a 0.8-mm Kirschner wire. Post-operative X-rays were taken at 2, 6, and 12 weeks, with bony healing assessed by a blinded MSK radiologist using an established radiographic scoring system. The reconstructed radii were retrieved at 12 weeks and analysed using bone histomorphometry and microCT. Kruskal-Wallis and Mann-Whitney tests were utilised to compare groups, with statistical significance when p<0.05. Radiographic analysis revealed no differences in periosteal reaction and degree of osteotomy site union between the groups at any time point. Less cortical remodeling was observed in R and I grafts compared to untreated controls at 6 weeks (p=0.004), but was no longer evident by 12 weeks. Radiographic union was achieved in all groups by 12 weeks. Histologic and microCT analysis further confirmed union at the graft-host bone interface, with the presence of mineralising callus and osteoid. Histomorphometry also showed the bridging external callus originated from host bone periosteum and a distinct cement line between allograft and host bone was present at the union site. Previous studies have shown that the presence of non-enzymatic glycation end products in bone can impair fracture healing. However, these studies investigated bony healing in the setting of diabetic states. Our findings showed that under normal conditions, ribose pretreated grafts healed at rates similar to controls via mechanisms also seen in retrieved human allografts clinically in use. These findings that grafts pretreated with our method are biocompatible with host bone in the rabbit help to further advance this technology for clinical trials

Aims

The aim of this study was to investigate the global and local impact of fat on bone in obesity by using the diet-induced obese (DIO) mouse model.

Sacral insufficiency fractures are not uncommon in elderly patients. We have diagnosed 20 cases in a five-year period, and have reviewed the clinical records, radiographs, CT and bone scans. We also assessed the degree of osteoporosis by measuring bone density using dual-energy X-ray absorptiometry and bone histomorphometry, and monitored the patients' functional outcome. Bone scans were positive in all 20 patients, CT showed a fracture or sclerosis in 7 of 12 patients and was useful in excluding malignancy. Plain radiographs were the least helpful, showing sclerosis in only 4 of the 20 patients. Involutional osteoporosis with a reduced bone formation rate was the most common underlying cause. Seventeen patients had complete resolution of pain within nine months, and no patient lost independence in daily activities. Increased awareness of these fractures may help to avoid unnecessary investigation and treatment. Bedrest and analgesia followed by rehabilitation provide good relief of symptoms

Introduction Bone loss and increased bone fragility may occur following long-term steroid therapy resulting in painful vertebral fractures. To fully understand the mechanisms underlying steroid-induced osteoporosis and to test potential spinal implants a large animal model is needed. The sheep is appropriate since bone remodelling is similar to humans and the vertebral body dimensions permit easy surgical manipulation. This study was undertaken to fully characterise the sheep as a model of steroid-induced vertebral osteoporosis and to evaluate its suitability for testing balloon kyphoplasty. Methods Osteoporosis was induced in ten lactating ewes (mean age 8 years) by ovariectomy, weekly injection of 54mg dexamethasone (Dexafort, Intervet, Australia) and a diet containing 0.2% calcium for up to 6 months. Baseline and endpoint iliac crest biopsies were taken to measure static histomorphometric indices of bone formation and resorption. Control animals were not ovariectomised and not treated with steroids. Dual energy X-ray absorptiometry (DXA, Hologic QDR 1000+, USA) was used to monitor bone mineral density (BMD) in the lumbar spine (L2-L5) after 0, 3 and 6 months of steroid treatment. At each time interval sheep were killed by barbiturate injection and the entire lumbar spine (L1-L6) was processed for histology, quantitative histomorphometry, mechanical testing, micro-CT (computed tomography) and ex-vivo trials to inflate kyphoplasty balloon tamps. Results After six months of treatment, BMD in the lumbar spine decreased by 29.5% from baseline. Trabecular bone volume of L2, L3 and L4 vertebrae (pooled) decreased by 31.4% (p< 0.05) and trabecular thickness decreased by 33.9%. Cortical bone thickness decreased by 43.9% (p< 0.05). The average load at which L1 yielded decreased by 67.4%. Static measurements of bone formation decreased by 68.3% and bone resorption increased 10 fold. Kyphoplasty balloon tamps were successfully inflated ex-vivo in vertebral bodies from treated animals. Discussion Using DXA, cancellous bone histomorphometry and mechanical testing, this study has demonstrated significant trabecular and cortical bone loss in the sheep lumbar spine up to six months after ovariectomy and continuous steroid treatment. These changes are the result of increased resorption and decreased formation of bone. The successful inflation of bone tamps in osteoporotic vertebrae ex-vivo is a prerequisite for in-vivo studies to assess the safety and efficacy of the kyphoplasty procedure

Aims

Distraction osteogenesis (DO) is a useful orthopaedic procedure employed to lengthen and reshape bones by stimulating bone formation through controlled slow stretching force. Despite its promising applications, difficulties are still encountered. Our previous study demonstrated that pulsed electromagnetic field (PEMF) treatment significantly enhances bone mineralization and neovascularization, suggesting its potential application. The current study compared a new, high slew rate (HSR) PEMF signal, with different treatment durations, with the standard Food and Drug Administration (FDA)-approved signal, to determine if HSR PEMF is a better alternative for bone formation augmentation.

Introduction: Vertebral compression fractures are common in osteoporosis, resulting in spinal deformities, severe back pain and decreased mobility. Vertebroplasty and kyphoplasty procedures aim to restore the integrity of the deformed vertebral body by injection of biocompatible cement. To date, there have been no long-term studies of the bone-cement interaction in this setting. A reliable large animal model of vertebral osteoporosis would be useful to fully characterise the disease process, to assess potential treatment regimens and to investigate the biocompatibility of bone cements used in kyphoplasty and vertebroplasty. The aim of this pilot study was to develop such a model with ovariectomy, low calcium diet and continuous steroid treatment. Methods: To induce osteoporosis, ten lactating ewes (mean age 8 years) were ovariectomised, injected weekly with 9 mg dexamethasone (Dexafort, Intervet, Australia) and fed low calcium diet. Weekly serum samples were taken to quantify generalised bone resorption (Type 1 collagen C-telopeptide [CTX], ‚-Cross Laps assay, Roche Diagnostics, Australia). Dual-energy X-ray absorptiometry (DEXA, Hologic QDR 1000+, USA) was used to monitor bone mineral density (BMD) in the lumbar spine (L3-L6) after 0, 2, 4, 6 and 9 months of treatment. At each time interval two sheep were killed by barbiturate injection. The entire lumbar spine (L1-L6) was processed for histology, quantitative histomorphometry, mechanical testing and micro-CT (computed tomography). Results: CTX levels increased rapidly after two months (p< 0.05). Baseline BMD in the lumbar spine (0.87±0.06 g/cm2) decreased by 16.9±3.8% or 2.72 standard deviations (p< 0.001) after nine months of treatment. Structural parameters of cancellous bone also showed osteoporotic change. Trabecular bone volume of L2, L3 and L6 vertebrae (pooled) progressively decreased from 24.9±1.2% at two months to 16.5±0.47% at nine months (p< 0.05). Trabecular thickness decreased from 0.14±0.01mm to 0.09±0.01mm, (p< 0.05) and trabecular spacing increased from 0.42±0.03mm to 0.47±0.02mm in the same period. The compressive load at which the L1 vertebrae failed decreased by 39.4% after 9 months. Discussion: This pilot study has demonstrated by DEXA, cancellous bone histomorphometry and mechanical testing, significant bone loss in the sheep lumbar spine up to nine months after ovariectomy and continuous steroid treatment. Assuming that the baseline BMD is representative of mature sheep, the changes in the lumbar spine could be interpreted as osteoporotic. Vertebral bone loss did not reach levels that would result in fracture. However, further work is underway using higher steroid doses to accelerate bone loss. This experimental model will be used to assess aspects of osteoporosis in general and vertebral augmentation procedures in particular

Aims

The effect of the gut microbiota (GM) and its metabolite on bone health is termed the gut-bone axis. Multiple studies have elucidated the mechanisms but findings vary greatly. A systematic review was performed to analyze current animal models and explore the effect of GM on bone.

Osteoporosis (OP) is a chronic metabolic bone disease characterized by the decrease of bone tissue per unit volume under the combined action of genetic and environmental factors, which leads to the decrease of bone strength, makes the bone brittle, and raises the possibility of bone fracture. However, the exact mechanism that determines the progression of OP remains to be underlined. There are hundreds of trillions of symbiotic bacteria living in the human gut, which have a mutually beneficial symbiotic relationship with the human body that helps to maintain human health. With the development of modern high-throughput sequencing (HTS) platforms, there has been growing evidence that the gut microbiome may play an important role in the programming of bone metabolism. In the present review, we discuss the potential mechanisms of the gut microbiome in the development of OP, such as alterations of bone metabolism, bone mineral absorption, and immune regulation. The potential of gut microbiome-targeted strategies in the prevention and treatment of OP was also evaluated.

Cite this article: Bone Joint Res 2020;9(8):524–530.

Corticosteroids are prescribed for the treatment of many medical conditions and their adverse effects on bone, including steroid-associated osteoporosis and osteonecrosis, are well documented. Core decompression is performed to treat osteonecrosis, but the results are variable. As steroids may affect bone turnover, this study was designed to investigate bone healing within a bone tunnel after core decompression in an experimental model of steroid-associated osteonecrosis. A total of five 28-week-old New Zealand rabbits were used to establish a model of steroid-induced osteonecrosis and another five rabbits served as controls. Two weeks after the induction of osteonecrosis, core decompression was performed by creating a bone tunnel 3 mm in diameter in both distal femora of each rabbit in both the experimental osteonecrosis and control groups. An in vivo micro-CT scanner was used to monitor healing within the bone tunnel at four, eight and 12 weeks postoperatively. At week 12, the animals were killed for histological and biomechanical analysis.

In the osteonecrosis group all measurements of bone healing and maturation were lower compared with the control group. Impaired osteogenesis and remodelling within the bone tunnel was demonstrated in the steroid-induced osteonecrosis, accompanied by inferior mechanical properties of the bone.

We have confirmed impaired bone healing in a model of bone defects in rabbits with pulsed administration of corticosteroids. This finding may be important in the development of strategies for treatment to improve the prognosis of fracture healing or the repair of bone defects in patients receiving steroid treatment.

Impacted bone allograft is often used in revision joint replacement. Hydroxyapatite granules have been suggested as a substitute or to enhance morcellised bone allograft. We hypothesised that adding osteogenic protein-1 to a composite of bone allograft and non-resorbable hydroxyapatite granules (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1.

After three weeks osteogenic protein-1 increased bone formation and the energy absorption of implants grafted with allograft and ProOsteon. A composite of allograft, ProOsteon and osteogenic protein-1 was comparable, but not superior to, allograft used on its own.

ProOsteon alone cannot be recommended as a substitute for allograft around non-cemented implants, but should be used to extend the volume of the graft, preferably with the addition of a growth factor.