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

Changes in Bone Turnover Markers after Osteoporotic Vertebral Compression Fractures in Males and Females

Background. To explore the normal changes in bone turnover markers (BTMs) and the correlations between the different BTMs after osteoporotic vertebral compression fracture (OVCF). Meanwhile, we explored the related differences that exist between sexes. Methods. A total of 130 OVCF patients were retrospectively reviewed. Using IBM SPSS 19.0 statistical software, the differences in the levels of BTMs and clinical parameters between sexes were assessed using Student’s unpaired $t$ test, and one-way ANOVA was used for the comparison of the three groups of samples. The correlations between P1NP, CTX, and clinical factors were assessed using Pearson’s correlation coefficient. Results. P1NP was 52.15 ng/ml within two weeks in male patients, and the level increased to 96.33 ng/ml after 12 weeks; in female patients, the increase was not as obvious as in male patients. CTX in male patients reached as much as approximately twice the initial value after 12 weeks. However, the situation in female patients was diverse. CTX was 0.58 ng/ml within two weeks and increased to 0.61 ng/ml within 2-12 weeks after the onset of OVCF. Subsequently, CTX decreased suddenly after 12 weeks. The increase in P1NP levels within 2 weeks after OVCF was significantly correlated with the levels of osteocalcin (OC) and bone-specific alkaline phosphatase (BAP). Changes in CTX within 2 weeks after OVCF were considerably related to phosphorus, 25 hydroxyvitamin D (25-OHD), OC, and BAP. Conclusion. The levels of P1NP and CTX increased differently in males and females after OVCF. The levels of OC and BAP were correlated with the levels of P1NP and CTX within 2 weeks of OVCF.

Microarchitecture of historic bone samples with tuberculosis

Tuberculosis is among the leading causes of death from infectious diseases and affects many organ systems, including the skeleton. Skeletal tuberculosis is an extrapulmonary stage of tuberculosis, which occurs after the early and post-primary pulmonary stages of the disease. The aim of our study was to assess the microarchitecture of historic dry bone samples of subjects who have died of tuberculosis documented by post-mortem examinations. These preparations date to the pre-antibiotic era, and were provided by the Pathological-Anatomical Collection in the “Fools Tower” of the Natural History Museum Vienna (PASiN-NHM).

We investigated macerated samples of 20 vertebral bodies, 19 femoral heads, and 20 tibiae of a total of 59 individuals diagnosed with tuberculosis from the nineteenth and early twentieth century. 10 femora and 10 tibiae from body donors that did not exhibit signs of infection and 10 (unaffected) vertebrae kept at the PASiN-NHM were studied as controls. The affected regions of the bone samples (and the corresponding regions of the control bones) were analyzed by microcomputed tomography using a Viscom X 8060 II system. Obtained images were analyzed semi-quantitatively. In samples with tuberculosis, independent of the investigated skeletal region, trabecular defects and decreased trabecular thickness were observed. Cortical porosity was seen in affected vertebrae and tibia; in tuberculous tibiae (but not in the femora) cortical thickness was decreased. In half of the individuals, cortical sclerosis was present; signs of ankylosis were observed mainly at the femoral heads affected with tuberculosis. We conclude that a combination of several alterations at the trabecular compartment could be suggestive of the presence of tuberculosis in historic skeletal remains.

Age-related alterations and senescence of mesenchymal stromal cells: Implications for regenerative treatments of bones and joints

The most common clinical manifestations of age-related musculoskeletal degeneration are osteoarthritis and osteoporosis, and these represent an enormous burden on modern society. Mesenchymal stromal cells (MSCs) have pivotal roles in musculoskeletal tissue development. In adult organisms, MSCs retain their ability to regenerate tissues following bone fractures, articular cartilage injuries, and other traumatic injuries of connective tissue. However, their remarkable regenerative ability appears to be impaired through aging, and in particular in age-related diseases of bones and joints. Here, we review age-related alterations of MSCs in musculoskeletal tissues, and address the underlying mechanisms of aging and senescence of MSCs. Furthermore, we focus on the properties of MSCs in osteoarthritis and osteoporosis, and how their changes contribute to onset and progression of these disorders. Finally, we consider current treatments that exploit the enormous potential of MSCs for tissue regeneration, as well as for innovative cell-free extracellular-vesicle-based and anti-aging treatment approaches.

Topographic modeling of early human osteoarthritis in sheep

Articular cartilage damage occurring during early osteoarthritis (OA) is a key event marking the development of the disease. Here, we modeled early human OA by gathering detailed spatiotemporal data from surgically induced knee OA development in sheep. We identified a specific topographical pattern of osteochondral changes instructed by a defined meniscal injury, showing that both cartilage and subchondral bone degeneration are initiated from the region adjacent to the damage. Alterations of the subarticular spongiosa arising locally and progressing globally disturbed the correlations of cartilage with subchondral bone seen at homeostasis and were indicative of disease progression. We validated our quantitative findings against human OA, showing a similar pattern of early OA correlating with regions of meniscal loss and an analogous late critical disturbance within the entire osteochondral unit. This translational model system can be used to elucidate mechanisms of OA development and provides a roadmap for investigating regenerative therapies.

Sex-determining region Y (SRY) attributes to gender differences in RANKL expression and incidence of osteoporosis

Receptor activator of nuclear factor κB ligand (RANKL) plays a crucial role in bone metabolism. RANKL gene misregulation has been implicated in several bone and cancer diseases. Here, we aimed to identify novel transcription regulators of RANKL expression. We discovered that transcription factors, sex-determining region Y (SRY) and c-Myb, regulate RANKL expression. We demonstrated that c-Myb increases and male-specific SRY decreases RANKL expression through direct binding to its 5’-proximal promoter. These results are corroborated by the gene expression in human bone samples. In osteoporotic men, expression of RANKL is 17-fold higher, which correlates with the drastically reduced expression (200-fold) of Sry, suggesting that in osteoporotic men, the upregulation of RANKL is caused by a decrease of Sry. In healthy men, the expression of RANKL is 20% higher than that in healthy women. Our data suggest that gender differences in RANKL expression and bone quality could be due to the sex-specific transcription factor SRY.

A male-specific gene offers clues to diagnosis and treatment of age-related osteoporosis. Osteoporosis was known to be linked to higher expression levels of RANKL, a gene that induces bone resorption, but the details were poorly understood. Nika Lovsin at the University of Ljubljana in Slovenia and co-workers searched for the genetic switches that control RANKL levels. They found that SRY, a gene on the male-specific Y chromosome, was a strong repressor of RANKL. In bone samples from osteoporotic men, expression levels of SRY levels were low and those of RANKL were high, suggesting that in men, when SRY fails to keep the bone-resorbing RANKL in check, osteoporosis results. SRY shows promise as an osteoporosis marker in men, or for development of treatment for both genders. Future research could address what triggers decreased SRY expression in men.

Section Plane Effects on Morphometric Values of Microcomputed Tomography

Objectives

Histomorphometry is the established gold standard for inspection of trabecular microstructures in biomaterial research. However, microcomputed tomography can provide images from the perspective of various section planes. The aim of the present study was to evaluate the effects of different section planes, which may cause bias in two-dimensional morphometry, on the morphometric values of microcomputed tomography.

Methods

A socket preservation technique was performed on the extracted premolar area of 4 beagle dogs. After an 8-week healing period, a total of 16 specimens were obtained and analyzed with conventional histomorphometry and microtomographic morphometry. Using the original images of the histologic specimens for comparison, the most similar tomographic image was selected by trial and error. Then, the section plane was then moved with ±79 μm parallel offsets and rotated ±10° around the center from the occlusal view. The images were compared in terms of bone, graft, and noncalcified area, and the concordance correlation coefficient (CCC) was calculated.

Results

There was a high CCC in the comparison between histomorphometric images and the most similar microtomographic images. However, the CCC value was low in the comparisons with both parallel movement and rotation. Our results demonstrate that the sectioning plane has a significant effect on measurements.

Conclusion

Two-dimensional morphometric values for biomaterial research should be interpreted with caution, and the simultaneous use of complementary 3-dimensional tools is recommended.

VEGF-A is associated with early degenerative changes in cartilage and subchondral bone

Paired cartilage and subchondral bone of subjects with no clinical history of joint disorders were analyzed to determine whether antioxidant enzymes, inflammatory cytokines and growth factors can be linked to a pre-osteoarthritis. Tissue explants were phenotyped according to Osteoarthritis Research Society International grading and micro-computed tomography, and also screened for the expression of several markers using quantitative polymerase chain reaction. The expression of these same genes was measured in SW1353 cells treated with hydrogen peroxide, to gain insight into the pathways involved with oxidative stress responses. Vascular endothelial growth factor A (VEGF-A) was up-regulated in the cartilage samples that showed early cartilage or bone degeneration. Oxidative stress in chondrocytes provoked up-regulation of interleukin-1β, interleukin-6, aggrecan, and SRY-box containing gene 9. Our results confirm the hitherto evidence of the deteriorating effects of the oxidative stress on cartilage and suggest the link between VEGF-A and pre-osteoarthritis.

Epigenetic enzymes influenced by oxidative stress and hypoxia mimetic in osteoblasts are differentially expressed in patients with osteoporosis and osteoarthritis

Epigenetic mechanisms including posttranslational histone modifications and DNA methylation are emerging as important determinants of bone homeostasis. With our case-control study we aimed to identify which chromatin-modifying enzymes could be involved in the pathology of postmenopausal osteoporosis and osteoarthritis while co-regulated by estrogens, oxidative stress and hypoxia. Gene expression of HAT1, KAT5, HDAC6, MBD1 and DNMT3A affected by oxidative stress and hypoxia in an in vitro qPCR screening step performed on an osteoblast cell line was analysed in trabecular bone tissue samples from 96 patients. Their expression was significantly reduced in patients with postmenopausal osteoporosis and osteoarthritis as compared to autopsy controls and significantly correlated with bone mineral density and several bone histomorphometry-derived parameters of bone quality and quantity as well as indicators of oxidative stress, RANK/RANKL/OPG system and angiogenesis. Furthermore, oxidative stress increased DNA methylation levels at the RANKL and OPG promoters while decreasing histone acetylation levels at these two genes. Our study is the first to show that higher expression of HAT1, HDAC6 and MBD1 is associated with superior quantity as well as quality of the bone tissue having a more favourable trabecular structure.

Visfatin alters the cytokine and matrix-degrading enzyme profile during osteogenic and adipogenic MSC differentiation

OBJECTIVES

Age-related bone loss is associated with bone marrow adiposity. Adipokines (e.g., visfatin, resistin, leptin) are adipocyte-derived factors with immunomodulatory properties and might influence differentiation of bone marrow-derived mesenchymal stem cells (MSC) in osteoarthritis (OA) and osteoporosis (OP). Thus, the presence of adipokines and MMPs in bone marrow and their effects on MSC differentiation were analyzed.

METHODS

MSC and ribonucleic acid (RNA) were isolated from femoral heads after hip replacement surgery of OA or osteoporotic femoral neck fracture (FF) patients. Bone structural parameters were evaluated by microcomputed tomography (μCT). MSC were differentiated towards adipocytes or osteoblasts with/without adipokines. Gene expression (adipokines, bone marker genes, MMPs, TIMPs) and cytokine production was evaluated by realtime-polymerase chain reaction (realtime-PCR) and enzyme-linked immunosorbent assay (ELISA). Matrix mineralization was quantified using Alizarin red S staining.

RESULTS

μCT showed an osteoporotic phenotype of FF compared to OA bone (reduced trabecular thickness and increased ratio of bone surface vs volume of solid bone). Visfatin and leptin were increased in FF vs OA. Visfatin induced the secretion of IL-6, IL-8, and MCP-1 during osteogenic and adipogenic differentiation. In contrast to resistin and leptin, visfatin increased MMP2 and MMP13 during adipogenesis. In osteogenically differentiated cells, MMPs and TIMPs were reduced by visfatin. Visfatin significantly increased matrix mineralization during osteogenesis, whereas collagen type I expression was reduced.

CONCLUSION

Visfatin-mediated increase of matrix mineralization and reduced collagen type I expression could contribute to bone fragility. Visfatin is involved in impaired bone remodeling at the adipose tissue/bone interface through induction of proinflammatory factors and dysregulated MMP/TIMP balance during MSC differentiation.

Older men with severe disc degeneration have more incident vertebral fractures-the prospective MINOS cohort study

OBJECTIVE

Data on the relationship between disc degeneration (DD) and fragility fractures in men are limited. The aim of this study was to prospectively analyse the risk of vertebral and non-vertebral fractures in men with thoracolumbar DD according to the severity of its radiological signs: disc space narrowing (DSN), osteophytes and endplate sclerosis.

METHODS

Men >50 years of age (n = 765) had lateral spine radiographs and DXA and were monitored prospectively. We analysed the risk of incident vertebral (7.5 years) and non-vertebral fractures (10 years) in men according to the severity of DD.

RESULTS

After adjustment for age and weight, BMD increased with increasing total DSN score, endplate sclerosis and osteophytosis. Over 7.5 years, 28 incident vertebral fractures occurred in 27 men. After adjustment for age, BMI, spine BMD, prior fractures and abdominal aortic calcifications, the vertebral fracture risk was 3-fold higher in the upper DSN quartile vs men without DSN. After adjustment for the same confounders, vertebral fracture risk was also nearly 3-fold higher in the upper DSN quartile vs the three lower quartiles combined. Over 10 years, 61 men sustained non-vertebral fragility fractures. After adjustment for age, BMI, hip BMD, abdominal aortic calcifications and prior falls and fractures, the non-vertebral fracture risk decreased with increasing DSN score. The risk of non-vertebral fracture was half as high in men above the median total DSN score vs men below the median.

CONCLUSION

In older men, severe DD is associated with higher BMD. Multilevel severe DSN is associated with higher vertebral fracture risk and lower non-vertebral fracture risk.

Mapping trabecular disconnection "hotspots" in aged human spine and hip

Trabecular bone disconnection is an independent factor in age-related skeletal failure where real termini (ReTm; rare in youth) may cause weakness disproportionate to tissue loss, yet their structural contribution at vulnerable locations remains uncertain. ReTm (previously recorded at the iliac crest) were mapped in "normal" aged vertebral bodies (T11-L5 autopsy; 20 females, 10 males) and corresponding proximal femora (autopsy; 10 females). Results were compared with biomechanically failed femora from orthopaedic subjects aged >58 yr (osteoporosis OP, 10 females; osteoarthritis OA, 10 females). A novel direct 2D/3D histological method was applied to large, thick (300 μm) slices superficially silver-stained to separate ReTm (unstained) from apparent termini (planar artefacts, brown). Light microscope field co-ordinates enabled ReTm mapping and statistical testing relative to i) sex, ii) tissue sector and iii) slicing plane. In men ReTm populations were small and random while in women they were large and sector-specific. In vertebrae they clustered anterior/superior being rare posterior/inferior; in the femoral head they concentrated distal/superior and also near the fovea, being fewer distal/inferior. A distribution polarity was evident with 100% more ReTm observed transversely (i.e., on tensile-related cross struts) than longitudinally (i.e., on compression-related vertical struts). Their numbers rose in OP (BV/TV<14%, microCT) and in OA (BV/TV>14%), remaining polarised and sector-specific in OP only. Comparative experimentation by marrow elution of an OP animal model demonstrated "floating segments" as a possible outcome. Conclusions were supported statistically that trabecular disconnection "hotspots" at vulnerable locations are sex- and sector-specific, mainly transaxial, and subject to disease modulation.

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.

Microstructural trabecular bone from patients with osteoporotic hip fracture or osteoarthritis: its relationship with bone mineral density and bone remodelling markers

Osteoporosis (OP) and osteoarthritis (OA) are the most prevalent musculoskeletal disorders in the elderly but the relationship between them is unclear. The purposes of this study are to analyze the bone turnover markers (BTM), bone mineral density (BMD) and the structural and mechanical properties of trabecular bone in patients with OP and OA, and to explore the relationship between these two diseases. We studied 12 OP patients and 13 OA patients. We analyzed BTM (β-CrossLaps and PINP), BMD and microstructural and biomechanical parameters (micro-CT). Our results were: OP group has higher levels of β-CrossLaps and lower BMD at the femoral neck. Also, OP patients have a decreased volume of trabecular bone and less trabecular number, with architecture showing prevalence of rod-like trabeculae and worse connectivity than OA patients. The biomechanical parameters were worse in OP patients. BMD was correlated with almost all the structural and biomechanical parameters. Moreover, β-CrossLaps was negatively correlated with hip BMD and with bone surface density and positively with trabecular separation. BTM, BMD and bone microstructural changes in osteoporosis are opposite to those of OA. These findings justify a less resistant bone with higher risk of fragility fractures in OP patients. These histomorphometric and biomechanical changes may be suspected by measuring of BMD and β-CrossLaps levels.

Dietary fatty acid content regulates wound repair and the pathogenesis of osteoarthritis following joint injury

OBJECTIVE

The mechanisms linking obesity and osteoarthritis (OA) are not fully understood and have been generally attributed to increased weight, rather than metabolic or inflammatory factors. Here, we examined the influence of fatty acids, adipokines, and body weight on OA following joint injury in an obese mouse model.

METHODS

Mice were fed high-fat diets rich in various fatty acids (FA) including saturated FAs (SFAs), ω-6 polyunsaturated FAs (PUFAs), and ω-3 PUFAs. OA was induced by destabilising the medial meniscus. Wound healing was evaluated using an ear punch. OA, synovitis and wound healing were determined histologically, while bone changes were measured using microCT. Activity levels and serum cytokines were measured at various time-points. Multivariate models were performed to elucidate the associations of dietary, metabolic and mechanical factors with OA and wound healing.

RESULTS

Using weight-matched mice and multivariate models, we found that OA was significantly associated with dietary fatty acid content and serum adipokine levels, but not with body weight. Furthermore, spontaneous activity of the mice was independent of OA development. Small amounts of ω-3 PUFAs (8% by kcal) in a high-fat diet were sufficient to mitigate injury-induced OA, decreasing leptin and resistin levels. ω-3 PUFAs significantly enhanced wound repair, SFAs or ω-6 PUFAs independently increased OA severity, heterotopic ossification and scar tissue formation.

CONCLUSIONS

Our results indicate that with obesity, dietary FA content regulates wound healing and OA severity following joint injury, independent of body weight, supporting the need for further studies of dietary FA supplements as a potential therapeutic approach for OA.

Molecular evidence of osteoblast dysfunction in elderly men with osteoporotic hip fractures

Osteoporosis is extremely frequent in post-menopausal women; nevertheless, osteoporosis in men is also a severe and frequently occurring but often underestimated disease. Increasing evidence links bone loss in male idiopathic osteoporosis and age related osteoporosis to osteoblast dysfunction rather than increased osteoclast activity as seen in postmenopausal osteoporosis. The aim of this study was to investigate gene expression of osteoblast related genes and of bone architecture in bone samples derived from elderly osteoporotic men with hip fractures (OP) in comparison to bone samples from age matched men with osteoarthritis of the hip (OA). Femoral heads and adjacent neck tissue were collected from 12 men with low-trauma hip fractures and consecutive surgical hip replacement. Bone samples of age matched patients undergoing hip replacement due to osteoarthritis served as controls. One half of the bone samples was subjected to RNA extraction, reverse transcription, and real-time polymerase chain reactions. The second half of the bone samples was analyzed by static histomorphometry. From each half samples from four different regions, the central and subcortical region of the femoral head and neck, were analyzed. OP patients displayed a significantly decreased RUNX2, Osterix and SOST expression compared to OA patients. Major microstructural changes in OP bone were seen in the subcortical region of the neck and were characterized by a significant decrease of bone volume, and a significant increase of trabecular separation. In conclusion, decreased local gene expression of RUNX2 and Osterix in men with hip fractures strongly supports the concept of osteoblast dysfunction in male osteoporosis. Major microstructural changes in the trabecular structure associated with osteoporotic hip fractures in men are localized in the subcortical region of the femoral neck.

The relationship between osteoarthritis and osteoporosis

The relationship between osteoarthritis (OA) and osteoporosis (OP), the two most common skeletal disorders related to aging, is controversial. Previous studies suggest that OA is inversely related to OP when studied cross-sectionally and systematically. However, there are differences in the results depending on the parameter used to define OA. The purpose of this review is to analyze and summarize the literature, and derive possible answers to three key questions along with a brief introduction on underlying mechanisms: (1) Is OA correlated to a high bone mineral density (BMD)? (2) Does OA influence the progression of OP or osteoporotic fractures? (3) Does high BMD affect the incidence and progression of OA? A review of the literature suggests that OA is inversely related to OP in general when studied cross-sectionally and systematically. However, when analyzed in individual bones, the BMD of the appendicular skeleton in OA-affected joints may decrease, particularly in the upper extremities. On whether OA influences bone loss or osteoporotic fractures, differences are observed according to the affected joints. The risk for osteoporotic fracture does not seem to decrease despite a high BMD in patients with OA, probably due to postural instability and muscle strength. Low BMD at the lumbar spine is associated with a lower incidence of knee OA although it does not arrest the progression of knee OA.

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.

Agreement between Histomorphometry and Microcomputed Tomography to Assess Bone Microarchitecture of Dental Implant Sites

BACKGROUND

Histomorphometry and microcomputed tomography (microCT) have been used in implant studies but need better understanding before being used as equivalent methods.

PURPOSE

The purpose of this study was to investigate the agreement between 2D (histomorphometry) and 3D (microCT) reference methods for assessing jawbone microarchitecture in vivo.

MATERIAL AND METHODS

Forty-four bone specimens from 32 patients were obtained during implant placement and examined by microCT, followed by hematoxylin-eosin staining and histomorphometric analysis. The morphometric parameters included bone volume density (BV/TV), bone surface fraction (BS/TV), bone surface density, trabecular thickness, trabecular number, and trabecular separation (Tb.Sp). Bland-Altman plots were used for pairwise agreement analysis between the equivalent 3D and 2D parameters, and complemented with Mountain plots. The association between the two methods was tested using Pearson's correlation followed by Passing-Bablok regression.

RESULTS

Systematic bias was observed in all Bland-Altman and Mountain plots, including constant bias for BV/TV and Tb.Sp, and proportional bias for all other parameters. Significant correlation was found for BV/TV (r = 0.80; p < .001) and BS/TV (r = 0.44; p = .003), and the Passing-Bablok regression showed constant bias for BV/TV and proportional bias for BS/TV.

CONCLUSION

Because of the poor agreement between measures obtained by histomorphometry and microCT, these methods should not be used interchangeably for jawbones.

Bone microarchitecture of the talus changes with aging

BACKGROUND

Fractures of the talus in the elderly are rare and usually result from high-impact injuries, suggesting only minor age-related bone structure changes. However, total ankle replacement failures with age often result from talar subsidence, suggesting age-related bone loss in the talus. Despite a number of histological analyses of talar microarchitecture, the effects of age and sex on talar microarchitecture changes remain poorly defined.

QUESTIONS/PURPOSES

The aim of this study was to analyze changes or differences in the trabecular microarchitecture of the talus with regard to (1) age and (2) sex.

METHODS

Sixty human tali were harvested from 30 patients at autopsy of three different age groups (20-40, 41-60, 61-80 years). The specimens were analyzed by radiography, micro-CT, and histological analysis. Given that there was no difference between the left and right talus, static histomorphometric parameters were assessed in three regions of interest of the right talus only (body, neck, head; n = 30).

RESULTS

The talar body, neck, and head were affected differently by age-related changes. The greatest loss of bone volume with age was seen in the talar body (estimate: -0.239; 95% confidence interval [CI], -0.365 to -0.114; p < 0.001). In the talar neck (estimate: -0.165; 95% CI, -0.307 to -0.023; p = 0.025), bone loss was only moderate and primarily was the result of reduction in trabecular thickness (estimate: -1.288; 95% CI, -2.449 to -0.127; p = 0.031) instead of number (estimate: -0.001; 95% CI, -0.005 to -0.003; p = 0.593). Bone structure changes were independent of sex.

CONCLUSIONS

Age-related bone structure changes predominantly occur in the talar body, which poses a potential risk factor for total ankle replacement loosening. The moderate changes in the talar neck might explain the persistent low incidence of talar neck fractures with age.

CLINICAL RELEVANCE

Our findings suggest that before total ankle replacement implantation, careful patient selection with dual-energy xray absorptiometry evaluation may be necessary to reduce the risk of talar implant subsidence.