Comparative high-resolution pQCT analysis of femoral neck indicates different bone mass distribution in osteoporosis and osteoarthritis

Spatial assessment of femoral neck bone density and microstructure in hip osteoarthritis

Osteoarthritis (OA) is known to involve profound changes in bone density and microstructure near to, and even distal to, the joint. Critically, however, a full, spatial picture of these abnormalities has not been well documented in a quantitative fashion in hip OA. Here, micro-computed tomography (44.8 μm/voxel) and data-driven computational anatomy were used to generate 3-D maps of the distribution of bone density and microstructure in human femoral neck samples with early (6F/4M, mean age = 51.3 years), moderate (14F/8M, mean age = 60 years), and severe (16F/6M, mean age = 63.3 years) radiographic OA. With increasing severity of radiographic OA, there was decreased cortical bone mineral density (BMD) (p=0.003), increased cortical thickness (p=0.001), increased cortical porosity (p=0.0028), and increased cortical cross-sectional area (p=0.0012, due to an increase in periosteal radius (p=0.018)), with no differences detected in the total femoral neck or trabecular compartment measures. No OA-related region-specific differences were detected through Statistical Parametric Mapping, but there were trends towards decreased tissue mineral density (TMD) in the inferior femoral neck with increasing OA severity (0.050 < p ≤ 0.091), possibly due to osteophytes. Overall, the lack of differences in cortical TMD among radiographic OA groups indicated that the decrease in cortical BMD with increasing OA severity was largely due to the increased cortical porosity rather than decreased tissue mineralization. As porosity is inversely associated with stiffness and strength in cortical bone, increased porosity may offset the effect that increased cortical cross-sectional area would be expected to have on reducing stresses within the femoral neck. The use of high-resolution imaging and quantitative spatial assessment in this study provide insight into the heterogeneous and multi-faceted changes in density and microstructure in hip OA, which have implications for OA progression and fracture risk.

A computational framework for canonical holistic morphometric analysis of trabecular bone

Bone is a remarkable, living tissue that functionally adapts to external loading. Therefore, bone shape and internal structure carry information relevant to many disciplines, including medicine, forensic science, and anthropology. However, morphometric comparisons of homologous regions across different individuals or groups are still challenging. In this study, two methods were combined to quantify such differences: (1) Holistic morphometric analysis (HMA) was used to quantify morphometric values in each bone, (2) which could then be mapped to a volumetric mesh of a canonical bone created by a statistical free-form deformation model (SDM). Required parameters for this canonical holistic morphometric analysis (cHMA) method were identified and the robustness of the method was evaluated. The robustness studies showed that the SDM converged after one to two iterations, had only a marginal bias towards the chosen starting image, and could handle large shape differences seen in bones of different species. Case studies were performed on metacarpal bones and proximal femora of different primate species to confirm prior study results. The differences between species could be visualised and statistically analysed in both case studies. cHMA provides a framework for performing quantitative comparisons of different morphometric quantities across individuals or groups. These comparisons facilitate investigation of the relationship between spatial morphometric variations and function or pathology, or both.

Influence of Extracellular Vesicles Isolated From Osteoblasts of Patients With Cox-Arthrosis and/or Osteoporosis on Metabolism and Osteogenic Differentiation of BMSCs

Background: Studies with extracellular vesicles (EVs), including exosomes, isolated from mesenchymal stem cells (MSC) indicate benefits for the treatment of musculoskeletal pathologies as osteoarthritis (OA) and osteoporosis (OP). However, little is known about intercellular effects of EVs derived from pathologically altered cells that might influence the outcome by counteracting effects from “healthy” MSC derived EVs. We hypothesize, that EVs isolated from osteoblasts of patients with hip OA (coxarthrosis/CA), osteoporosis (OP), or a combination of both (CA/OP) might negatively affect metabolism and osteogenic differentiation of bone-marrow derived (B)MSCs.

Methods: Osteoblasts, isolated from bone explants of CA, OP, and CA/OP patients, were compared regarding growth, viability, and osteogenic differentiation capacity. Structural features of bone explants were analyzed via μCT. EVs were isolated from supernatant of naïve BMSCs and CA, OP, and CA/OP osteoblasts (osteogenic culture for 35 days). BMSC cultures were stimulated with EVs and subsequently, cell metabolism, osteogenic marker gene expression, and osteogenic differentiation were analyzed.

Results: Trabecular bone structure was different between the three groups with lowest number and highest separation in the CA/OP group. Viability and Alizarin red staining increased over culture time in CA/OP osteoblasts whereas growth of osteoblasts was comparable. Alizarin red staining was by trend higher in CA compared to OP osteoblasts after 35 days and ALP activity was higher after 28 and 35 days. Stimulation of BMSC cultures with CA, OP, and CA/OP EVs did not affect proliferation but increased caspase 3/7-activity compared to unstimulated BMSCs. BMSC viability was reduced after stimulation with CA and CA/OP EVs compared to unstimulated BMSCs or stimulation with OP EVs. ALP gene expression and activity were reduced in BMSCs after stimulation with CA, OP, and CA/OP EVs. Stimulation of BMSCs with CA EVs reduced Alizarin Red staining by trend.

Conclusion: Stimulation of BMSCs with EVs isolated from CA, OP, and CA/OP osteoblasts had mostly catabolic effects on cell metabolism and osteogenic differentiation irrespective of donor pathology and reflect the impact of tissue microenvironment on cell metabolism. These catabolic effects are important for understanding differences in effects of EVs on target tissues/cells when harnessing them as therapeutic drugs.

Decreased trabecular bone deterioration of proximal tibiae and lumbar vertebrae in postmenopausal women with osteoarthritis

Osteoporosis and osteoarthritis (OA) are two common age-related skeletal disorders, which are associated with substantial morbidity and disability, particularly among elderly women. The present study was performed to investigate the trabecular bone deterioration of proximal tibiae and lumbar vertebrae in postmenopausal women with OA. The results demonstrated that the histomorphometric section of trabecular bone below the growth plate was markedly different between the healthy control and OA group. However, the loss of trabecular bone underneath the growth plate in the healthy control group was significantly worse than that of the OA group. Hematoxylin and eosin staining demonstrated the increased disconnection and separation of the trabecular bone network as well as the reduction of trabecular bone mass of primary and secondary spongiosa throughout the proximal metaphysis of tibia in the healthy control compared to the OA group; similar results were found when the same experiment was repeated on the lumbar vertebrae of healthy control subjects and OA patients from postmenopausal women. The biological properties of trabecular bone in the proximal tibia and lumbar vertebrae were measured in postmenopausal women with OA. Spearman's rank correlation analysis revealed that the bone volume fraction was both positively correlated with radiographic severity and Western Ontario McMaster University Osteoarthritis Index scores in in the proximal tibia and lumbar vertebrae from postmenopausal women with OA. In conclusion, the structural properties of the proximal tibia and lumbar vertebrae supported that an inverse correlation existed between postmenopausal women with OA and healthy controls. Moreover, there is an important protective mechanism of OA on trabecular microstructure in proximal tibiae and lumbar vertebrae from postmenopausal women.

Local Variation in Femoral Neck Cortical Bone: In Vitro Measured Bone Mineral Density, Geometry and Mechanical Properties

Age- and disease (osteoporotic fractured and osteoarthritic tissue)-related changes in the distribution of cortical bone were examined, using a multimodality approach, including measurement of local density, geometry and mechanical properties, where changes in these properties can give rise to instability and increasing probability of fracture. In contrast to the majority of previously reported research, this study also focuses on the characteristic non-circular femoral neck cross-sectional geometry and variation in bone mineral density (BMD) around the femoral neck. Twenty-two osteoarthritic and 7 osteoporotic femoral neck slices, collected from elective and trauma-related arthroplasty, and 16 cadaveric donor tissue controls were tested mechanically using Reference Point Indentation (BioDent™, Active Life Technologies®, Santa Barbara, CA) and then scanned with in vitro-based radiography intended to replicate the dual-energy X-ray absorptiometry technique. All parameters were measured regionally around the circumference of the femoral neck, allowing examination of spatial variability within the cortical bone. Fractured tissue was less resistant to indentation in the thinner superolateral segment compared to other segments and other groups. BMD around the fractured femoral necks appeared more consistent than that of nonfractured tissue, where BMD was reduced in the superolateral segment for the other groups. Cortical bone was thin in the superolateral segment for all groups except for the osteoarthritic group, and was thicker in the inferomedial segment for both osteoarthritic and fractured groups, resulting in the largest variation in buckling ratio (ratio of cortical bone diameter to cortical bone thickness) around the femoral neck for the fractured group. With age, healthy controls appeared to have lower inferomedial cortical thickness, whereas no significant differences in Reference Point Indentation measurements and density were observed. The study has highlighted several (both quality- and quantity-related) parameters that may be used to improve prediction of fracture risk.

Evidence for Altered Canonical Wnt Signaling in the Trabecular Bone of Elderly Postmenopausal Women with Fragility Femoral Fracture

Wnt signaling, a major regulator of bone formation and homeostasis, might be involved in the bone loss of osteoporotic patients and the consequent impaired response to fracture. Therefore we analyzed Wnt-related, osteogenic, and adipogenic genes in bone tissue of elderly postmenopausal women undergoing hip replacement for either femoral fracture or osteoarthritis. Bone specimens derived from the intertrochanteric region of the femurs of 25 women with fracture (F) and 29 with osteoarthritis without fracture (OA) were analyzed. Specific miRNAs were analyzed in bone and in matched blood samples. RUNX2, BGP, and OPG showed lower expression in F than in OA samples, while OSX, OPN, BSP, and RANKL were not different. Inhibitory genes of Wnt pathway were lower in F versus OA. β-Catenin protein levels were higher in F versus OA, whereas its cotranscriptional regulator (Lef1) was lower in F group. miR-204, which targets RUNX2, and miR-130a, which inhibits PPARγ, were lower and higher, respectively, in F versus OA serum samples. The present study showed an inefficient Wnt signal transduction in F group despite higher β-catenin protein levels, consistent with the expected overall postfracture systemic activation towards osteogenesis. This transcriptional inefficiency could contribute to the osteoporotic bone fragility.

Bone mineral density distribution in the proximal femur and its relationship to morphologic factors in progressed unilateral hip osteoarthritis

Although an adverse relationship between osteoporosis and osteoarthritis (OA) has been reported, it remains controversial. In most previous reports of OA, bone mineral density (BMD) changes in the subtrochanteric region have not been clarified, whilst BMD of the femoral neck and trochanteric region has been well investigated. In our current study, we investigated the BMD ratio compared to the contralateral side in the whole proximal femurs of hip OA patients. We aimed to clarify the morphologic factor that may influence these BMD ratios. We performed dual energy X-ray absorptiometry (DEXA) analysis of 69 hip joints from unilateral progressed OA cases. The minimum joint space, center edge angle, Sharp angle, acetabular head index, neck-shaft angle, and leg length discrepancy were also measured as radiographic factors. The correlation between BMD ratio and radiographic morphologic factors was then evaluated by logistic regression. The BMD ratio was higher in the femoral neck than in the distal region. In terms of radiographic factors, the neck-shaft angle was revealed to influence the decreased BMD ratio in the distal subtrochanteric part, whilst the leg length discrepancy and Sharp angle showed a relationship with the increased BMD ratio in the proximal neck region. The discrepancy in the BMD ratio between the femoral neck and the distal subtrochanteric region in the proximal femur is influenced by several morphologic factors.

A novel 3D-printed device for localization and extraction of trabeculae from human femoral heads: a comparison with traditional visual extraction

In this study, we propose a novel method for accurate trabeculae extraction from human femoral heads using 3D-printing techniques and compare spatial deviation errors between this novel method and the conventional method. We found that spatial deviation errors, which indicate inaccuracy and unreliability, were significantly higher with the conventional method.

INTRODUCTION

Assessment of structural and mechanical properties of local bone is important in the study of pathological changes associated with musculoskeletal degenerative diseases. However, the widely used visual extraction method (VIS) for trabecular columns showed large deviations from veridicality, referred to as spatial deviation errors (SDE). Here, we propose a novel method for accurately locating and trephining trabeculae using a 3D-printed (3DP) positioning device and also evaluate the SDE of the VIS.

METHODS

Twenty femoral heads were obtained from osteoporotic patients, and the trabecular columns were extracted from the principal compressive trabeculae by VIS (n = 10) or the 3DP (n = 10) method. Morphological, structural, and mechanical properties were compared between both groups along with the recorded errors in spatial deviation.

RESULTS

Compared with the 3DP group, the average angle of central axis deflection in the VIS group was significantly greater; SDE in the VIS group was 26.1, 8.8, 4.1, 9.8, 7.2, 8.1, and 10.1 % greater for bone mineral density, bone volume/tissue volume ratio, trabecular thickness, trabecular number, Young's modulus, yield strength, and ultimate strength.

CONCLUSION

In this study, a high degree of SDE was demonstrated in the VIS, which indicates that the conventional technique is unreliable. Additionally, accurate sample fabrication and credible quantitative analysis of local trabeculae among individuals can be achieved with the aid of computed tomography and the 3DP device, thus providing a more objective method for researching musculoskeletal degenerative diseases and possibly a better clinical understanding of these disorders.

Comparison of microstructural and mechanical properties of trabeculae in femoral head from osteoporosis patients with and without cartilage lesions: a case-control study

Background

Degeneration of cartilage will change load distribution, affecting bone remodeling progress and trabecular structure and strength. However, in human primary osteoporosis, whether cartilage lesions would also affect properties beneath trabecular bone remains unknown. In this study, we explored the differences in local trabecular properties between osteoporosis patients with and without cartilage lesions.

Methods

Eighteen pairs of femoral heads with and without cartilage lesions in a weight-bearing area were collected from senile femoral neck fracture patients. The Mankin score and glycosaminoglycan (GAG) content were used to evaluate the severity of the cartilage lesions. Micro-CT and compression tests were used to obtain structural and mechanical characteristics of each trabecular column. Multivariate linear regression was performed to evaluate the association between mechanical parameters and the degree of cartilage lesion.

Results

In osteoporosis patients with cartilage lesions, the bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) of the trabecular column were significantly higher than that of osteoporotic control patients (all P < 0.05), while the Young’s modulus was lower (P = 0.024). Multivariable linear regression indicated that in both groups, bone mineral density (BMD) significantly correlated with Young’s modulus (all P < 0.05). While in patients with cartilage lesion, GAG content was also correlated with Young’s modulus (standardized coefficient 0.443, P < 0.01).

Conclusions

Osteoporosis patients with cartilage lesions exhibited a weaker mechanical property of trabeculae. The intimate association of cartilage lesions and impairment of trabecular mechanical properties indicate that cartilage and trabeculae belong to an interdependent functional unit. Previously proposed adaptive mechanisms in osteoarthritis might also be applicable to the progression of osteoporosis.

Histomorphometric bone assessment in patients with fracture of the proximal end of the femur

OBJECTIVE:

To determine whether there is a difference on the bone architecture in patients with femoral neck fracture compared to patients with intertrochanteric fractures and assess the importance of aging on bone microarchitecture in patients with proximal femoral fracture.

METHODS:

Biopsy of the iliac crest was made in seventeen patients between 55 and 90 years old who were admitted to the emergency room with fractures of the proximal end of the femur. After a small fragment was removed, we made a histomorphometric analysis of it.

RESULTS:

There was no significant difference between patients with femoral neck fracture and trochanteric fracture in structural parameters, formation and resorption. Comparing age groups we also did not find any significant change between the groups in the parameters volume and trabecular separation.

CONCLUSION:

There are no difference in the morphometric parameters analyzed between the different types of fracture and age is not a significant factor in the alteration of these parameters.

Level of Evidence II, Diagnostic Studies.

Histomorphometric analysis of the femoral neck in patients with and without femoral neck fracture

OBJECTIVE:

To determine, through bone histomorphometry in femoral neck, whether there are differences in the cancellous bone of the proximal femur from female patients over 60 years old who had femoral neck fracture and similar patients who did not have such fracture.

METHODS:

We analyzed the trabecular part of the femur of 13 female patients, aged over 60 years old, by the bone histomorphometry method. Seven of these patients had femoral neck fracture. All of them were subjected to hip arthroplasty.

RESULTS:

Bone densitometry showed no significant difference. There was no significant difference on the average thickness of the trabecular bone (124.38µm versus 147.09µm). The number of bone trabeculae was lower (1.52, versus 1.88) and the separation between them was larger (541,19µm versus 391,14µm) in the fracture group.

CONCLUSION:

A difference in histomorphometric parameters of cancellous bone of the femur neck was observed among patients who had fractures as compared to patients who had not.

Level of Evidence II, Diagnostic Studies.

Application of high resolution pQCT analysis for the assessment of a bone lesion: a technical note

Peripheral quantitative computed tomography (pQCT) has found new fields of application in bone medicine, but none of them concerns the forensic practice. This study exposes the potential of pQCT applied to a penetrating lesion in a vertebral body. A pQCT scanner was used for the measurements (XCT Research SA+; Stratec Medizintechnik GmbH, Pforzheim, Germany). A more precise reconstruction of the path of the lesion within the trabecular bone was reached, with more details concerning the morphological characteristics of the lesion inside the vertebral body, and the elaboration of a 3D model was created, which allowed the operator to define the volume of the lack of tissues related to the lesion. The application of pQCT scan proved to be a potentially useful tool for the assessment of bone lesions, although further studies are needed in order to verify its applicability to forensic context.

Extra-virgin olive oil diet and mild physical activity prevent cartilage degeneration in an osteoarthritis model: an in vivo and in vitro study on lubricin expression

Mediterranean diet includes a relatively high fat consumption mostly from monounsaturated fatty acids mainly provided by olive oil, the principal source of culinary and dressing fat. The beneficial effects of olive oil have been widely studied and could be due to its phytochemicals, which have been shown to possess anti-inflammatory properties. Lubricin is a chondroprotective glycoprotein and it serves as a critical boundary lubricant between opposing cartilage surfaces. A joint injury causes an initial flare of cytokines, which decreases lubricin expression and predisposes to cartilage degeneration such as osteoarthritis. The aim of this study was to evaluate the role of extra-virgin olive oil diet and physical activity on inflammation and expression of lubricin in articular cartilage of rats after injury. In this study we used histomorphometric, histological, immunocytochemical, immunohistochemical, western blot and biochemical analysis for lubricin and interleukin-1 evaluations in the cartilage and in the synovial fluid. We report the beneficial effect of physical activity (treadmill training) and extra-virgin olive oil supplementation, on the articular cartilage. The effects of anterior cruciate ligament transection decrease drastically the expression of lubricin and increase the expression of interleukin-1 in rats, while after physical activity and extra-virgin olive oil supplemented diet, the values return to a normal level compared to the control group. With our results we can confirm the importance of the physical activity in conjunction with extra-virgin olive oil diet in medical therapy to prevent osteoarthritis disease in order to preserve the articular cartilage and then the entire joint.

Osteoporosis and osteoarthritis, rheumatoid arthritis and spondylarthropathies

Osteoporosis (OP) commonly occurs in the setting of inflammatory arthritis, whereas there is an inverse relationship with osteoarthritis (OA). We review the recent updates in epidemiology and pathophysiology of OP relating to several arthridities. In ankylosing spondylitis, lateral lumbar spine dual x-ray absorptiometry is better at detecting osteoporosis compared with the AP view and patients receiving treatment with anti- tumor necrosis factor medications had lower levels of bone turnover markers. With regard to rheumatoid arthritis, anticitrullinated peptide positivity without clinical arthritis as well as higher levels of interleukin-6 is associated with decreased bone mineral density and polymorphisms in the vitamin D receptor in RA patients may predispose to OP. With regard to OA, results from the Global Longitudinal Study of Osteoporosis in Women study and several radiological studies suggest that differences in the distribution of bone mass at the femoral neck may account for the inverse relationship of OA and OP, and several studies suggest that OA and OP have opposing cytokine and bone metabolism marker profiles.

Osteoarthritic versus osteoporotic bone and intra-skeletal variations in normal bone: evaluation with µCT and bone histomorphometry

Several studies have shown that in contrast to osteoporosis (OP), osteoarthritis (OA) is characterized by high bone mineral density (BMD). Bone strength not only depends on mineral content as determined by dual X-ray absorptiometry (DXA), but also on bone microarchitecture. We studied intertrochanteric bone from normal controls and OA and OP patients by bone histomorphometry (BHM) and microcomputed tomography (µCT) as well as DXA in order to first, test the differences between OA and OP comparing both groups to healthy controls, second, to assess variations between three different skeletal sites in controls and third, to determine the level of agreement between µCT, BHM, and DXA. Analysis was performed on 115 samples from OA and OP patients, and controls. We found significant differences between OA and OP samples in structural parameters and in the osteoid fraction (p < 0.05). The majority of the intra-skeletal differences were shown between lumbar spine and femoral head samples (p < 0.05). Significant agreements were found between µCT and BHM and DXA (r = 0.32-0.45, p < 0.05). Our findings suggest differences in intertrochanteric bone between OA and OP, the age-related intra-skeletal variations and a correlation between microscopic and macroscopic bone evaluation methods.

The effects of physical activity on apoptosis and lubricin expression in articular cartilage in rats with glucocorticoid-induced osteoporosis

Glucocorticoids are considered the most powerful anti-inflammatory and immunomodulating drugs. However, a number of side-effects are well documented in different diseases, including articular cartilage, where increases or decreases in the synthesis of hormone-dependent extracellular matrix components are seen. The objective of this study has been to test the effects of procedures or drugs affecting bone metabolism on articular cartilage in rats with prednisolone-induced osteoporosis and to evaluate the outcomes of physical activity with treadmill and vibration platform training on articular cartilage. The animals were divided into 5 groups, and bone and cartilage evaluations were performed using whole-body scans and histomorphometric analysis. Lubricin and caspase-3 expression were evaluated by immunohistochemistry, Western blot analysis and biochemical analysis. These results confirm the beneficial effect of physical activity on the articular cartilage. The effects of drug therapy with glucocorticoids decrease the expression of lubricin and increase the expression of caspase-3 in the rats, while after physical activity the values return to normal compared to the control group. Our findings suggest that it might be possible that mechanical stimulation in the articular cartilage could induce the expression of lubricin, which is capable of inhibiting caspase-3 activity, preventing chondrocyte death. We can assume that the physiologic balance between lubricin and caspase-3 could maintain the integrity of cartilage. Therefore, in certain diseases such as osteoporosis, mechanical stimulation could be a possible therapeutic treatment. With our results we can propose the hypothesis that physical activity could also be used as a therapeutic treatment for cartilage disease such as osteoarthritis.

Enhanced trabecular micro-architecture of the femoral neck in hip osteoarthritis vs. healthy controls: a micro-computer tomography study in postmenopausal women

PURPOSE

A controversial relationship between osteoarthritis (OA) and bone fragility has been attracting considerable attention. However, despite interest in the effects of OA on femoral neck fracture risk and numerous studies analysing the changes in the arthritic femoral head, there is insufficient data about femoral neck 3D bone micro-architecture in individuals with hip osteoarthritis. We compared trabecular micro-architecture of the femoral neck between postmenopausal women with coxarthrosis and controls to explore whether coxarthrosis may indicate reduced bone fragility from the trabecular micro-architectural perspective.

METHODS

The study sample included nine women with hip osteoarthritis and 13 age-matched controls. The femoral neck sections were scanned using micro-computed tomography, evaluating the cancellous bone from the superolateral and inferomedial neck subregions.

RESULTS

Osteoarthritic subjects demonstrated a general trend of improved trabecular micro-architecture in both analysed subregions when compared with age-matched controls. In particular, several architectural properties that are important predictors of cancellous bone strength showed significantly better values in the OA group, even after adjusting for bone volume fraction. Namely, the OA group expressed higher trabecular connectivity (p = 0.008), lower SMI indicating more plate-like structure (p = 0.005), and reduced anisotropy (p = 0.006) particularly in the inferomedial neck. Osteoarthritic cases also trended towards higher BV/TV, particularly in the superolateral neck. All micro-architectural parameters displayed significant regional heterogeneity (p ≤ 0.01), with the inferomedial neck region showing more favourable values than the superolateral region.

CONCLUSIONS

Enhanced trabecular micro-architecture of the femoral neck in postmenopausal osteoarthritic subjects suggests reduced cancellous bone fragility in comparison with their age-matched healthy controls.