Is osteoarthritis a systemic disorder of bone?

ENPP1 in Blood and Bone: Skeletal and Soft Tissue Diseases Induced by ENPP1 Deficiency

The enzyme ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) codes for a type 2 transmembrane glycoprotein that hydrolyzes extracellular ATP to generate pyrophosphate (PPi) and adenosine monophosphate, thereby contributing to downstream purinergic signaling pathways. The clinical phenotypes induced by ENPP1 deficiency are seemingly contradictory and include early-onset osteoporosis in middle-aged adults and life-threatening vascular calcifications in the large arteries of infants with generalized arterial calcification of infancy. The progressive overmineralization of soft tissue and concurrent undermineralization of skeleton also occur in the general medical population, where it is referred to as paradoxical mineralization to highlight the confusing pathophysiology. This review summarizes the clinical presentation and pathophysiology of paradoxical mineralization unveiled by ENPP1 deficiency and the bench-to-bedside development of a novel ENPP1 biologics designed to treat mineralization disorders in the rare disease and general medical population.

Biomechanical Impact of Phosphate Wasting on Articular Cartilage Using the Murine Hyp Model of X-linked hypophosphatemia

Degenerative osteoarthritis (OA) is recognized as an early-onset comorbidity of X-linked hypophosphatemia (XLH), contributing to pain and stiffness and limiting range of motion and activities of daily living. Here, we extend prior findings describing biochemical and cellular changes of articular cartilage (AC) in the phosphate-wasting environment of XLH to determine the impact of these changes on the biomechanical properties of AC in compression and potential role in the etiology of OA. We hypothesize that despite increased proteoglycan biosynthesis, disruption of the mineralized zone of AC impacts the mechanical properties of cartilage that function to accommodate loads and that therapeutic restoration of this zone will improve the mechanical properties of AC. Data were compared between three groups: wild type (WT), Hyp, and Hyp mice treated with calcitriol and oral phosphate. EPIC microCT confirmed AC mineral deficits and responsiveness to therapy. MicroCT of the Hyp subchondral bone plate revealed that treatment improved trabecular bone volume (BV/TV) but remained significantly lower than WT mice in other trabecular microstructures (p < 0.05). Microindentation AC studies revealed that, compared with WT mice, the mean stiffness of tibial AC was significantly lower in untreated Hyp mice (2.65 ± 0.95 versus 0.87 ± 0.33 N/mm, p < 0.001) and improved with therapy (2.15 + 0.38 N/mm) to within WT values. Stress relaxation of AC under compressive loading displayed similar biphasic relaxation time constants (Taufast and Tauslow) between controls and Hyp mice, although Tauslow trended toward slowed relaxation times. In addition, Taufast and Tauslow times correlated with peak load in WT mice (r = 0.80; r = 0.78, respectively), whereas correlation coefficient values for Hyp mice (r = 0.46; r = 0.21) improved with treatment (r = 0.71; r = 0.56). These data provide rationale for therapies that both preserve AC stiffness and recovery from compression. The Hyp mouse also provides unique insight into determinants of structural stiffness and the viscoelastic properties of AC in the progression of OA. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Controlling Microenvironments with Organs-on-Chips for Osteoarthritis Modelling

Osteoarthritis (OA) remains a prevalent disease affecting more than 20% of the global population, resulting in morbidity and lower quality of life for patients. The study of OA pathophysiology remains predominantly in animal models due to the complexities of mimicking the physiological environment surrounding the joint tissue. Recent development in microfluidic organ-on-chip (OoC) systems have demonstrated various techniques to mimic and modulate tissue physiological environments. Adaptations of these techniques have demonstrated success in capturing a joint tissue's tissue physiology for studying the mechanism of OA. Adapting these techniques and strategies can help create human-specific in vitro models that recapitulate the cellular processes involved in OA. This review aims to comprehensively summarise various demonstrations of microfluidic platforms in mimicking joint microenvironments for future platform design iterations.

The role of TGF-beta3 in cartilage development and osteoarthritis

Articular cartilage serves as a low-friction, load-bearing tissue without the support with blood vessels, lymphatics and nerves, making its repair a big challenge. Transforming growth factor-beta 3 (TGF-β3), a vital member of the highly conserved TGF-β superfamily, plays a versatile role in cartilage physiology and pathology. TGF-β3 influences the whole life cycle of chondrocytes and mediates a series of cellular responses, including cell survival, proliferation, migration, and differentiation. Since TGF-β3 is involved in maintaining the balance between chondrogenic differentiation and chondrocyte hypertrophy, its regulatory role is especially important to cartilage development. Increased TGF-β3 plays a dual role: in healthy tissues, it can facilitate chondrocyte viability, but in osteoarthritic chondrocytes, it can accelerate the progression of disease. Recently, TGF-β3 has been recognized as a potential therapeutic target for osteoarthritis (OA) owing to its protective effect, which it confers by enhancing the recruitment of autologous mesenchymal stem cells (MSCs) to damaged cartilage. However, the biological mechanism of TGF-β3 action in cartilage development and OA is not well understood. In this review, we systematically summarize recent progress in the research on TGF-β3 in cartilage physiology and pathology, providing up-to-date strategies for cartilage repair and preventive treatment.

Association between radiographic hand osteoarthritis and bone microarchitecture in a population-based sample

Background

Subchondral bone plays an important role in the pathogenesis of radiographic osteoarthritis (OA). However, the bony changes that occur in hand OA (HOA) are much less understood. This study aimed to describe the association between radiographic HOA and high-resolution peripheral quantitative computed tomography (HRpQCT) measures of the hand and radius in a population-based sample.

Methods

A total of 201 participants (mean age 72, 46% female) from the Tasmanian Older Adult Cohort (TASOAC) study underwent HRpQCT assessment of the 2nd distal and proximal interphalangeal (DIP, PIP), 1st carpometacarpal (CMC) joint, and distal radius. Radiographic HOA was assessed at the 2nd DIP, PIP joints, and the 1st CMC joint using the OARSI atlas.

Results

Proximal osteophyte and joint space narrowing (JSN) scores were consistently more strongly associated with HRpQCT measures compared to the distal site with positive associations for indices of bone size (total and trabecular bone area and cortical perimeter but inconsistent for cortical area) and negative associations for volumetric bone mineral density (vBMD). There was a decrease in trabecular number and bone volume fraction with increasing osteophyte and JSN score as well as an increase in trabecular separation and inhomogeneity. Osteophyte and JSN scores in the hand were not associated with HRpQCT measures at the distal radius.

Conclusions

This hypothesis generating data suggests that bone size and trabecular disorganization increase with both osteophyte formation and JSN (proximal more than distal), while local vBMD decreases. This process appears to be primarily at the site of pathology rather than nearby unaffected bone.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02907-6.

Enthesopathy-An Underappreciated Role in Osteoarthritis?

Osteoarthritis (OA) continues to be a debilitating disease worldwide, to date, no therapies have been definitely proven to modify disease progression or moderate symptom relief long term other than joint replacement. A contributing factor may be the lack of attention to the potential role of the periarticular enthesis and development and progression of OA. The enthesis is the site of attachment for a tendon, ligament, or joint capsule to the bony skeleton, thereby allowing centralized transmission and dissipation of mechanical loads. Because of this design, the enthesis is a site of stress concentration subject to inflammation during sports-related activities or spondyloarthropathies, which may lead to long-term degeneration. Our hypothesis is that functional incompetence of the enthesis resulting from either degenerative or inflammatory changes could be an initiating factor for OA and may thus provide a novel basis for the development of future disease management in this phenotype of patients.

MK801 regulates the expression of key osteoarthritis factors in osteoarthritis synovial fibroblasts through complement C5

BACKGROUND

Osteoarthritis is currently one of the most common chronic diseases. As life expectancy increases, its prevalence and incidence are expected to rise. At present, more and more evidences prove the correlation between the complement system and osteoarthritis (OA). This study aims to investigate complement C5's influence on the effect of MK801 on osteoarthritis synovial fibroblasts (OA-SFs).

METHODS

We used IL-1b to induce OA-SFs derived from mice to obtain OA-SFs. And we performed RT-PCR and Western Blot assays to evaluate the expression levels of associated mRNA and protein. The alteration of MAC expression on OA-SFs cell membrane was evaluated by immunofluorescence assay. The expression of related inflammatory factors of OA-SFs was evaluated by ELISA experiment.

RESULTS

MK801 could significantly inhibit the expression of osteoarthritis (OA) marker factors, such as: membrane attack complex (MAC), tumor necrosis factor-α (TNF-α) and matrix metalloproteinase-13 (MMP13). Meanwhile, MK801 can significantly inhibit the expression of complement C5 (C5) in OA-SFs. Immunofluorescence assay showed that MAC expression on OA-SFs cell membrane was significantly inhibited by MK801. The nucleo-plasmic separation experiment demonstrated that MK801 could significantly inhibit the activation of Nuclear factor-κB (NF-κB) signaling pathway in OA-SFs. Futhermore, koncking down the expression of C5 reversed the inhibition MK801 on the expression of OA-SFs inflammatory factors.

CONCLUSIONS

These results illustrated two points: first, MK801 inhibited the generation of MAC and the release of inflammation factors in OA-SFs through C5; second: MK801 inhibited the activation of NF-κB signaling pathway in OA-SFs.

Bone phenotypes in rheumatology - there is more to bone than just bone

Osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, all have one clear common denominator; an altered turnover of bone. However, this may be more complex than a simple change in bone matrix and mineral turnover. While these diseases share a common tissue axis, their manifestations in the area of pathology are highly diverse, ranging from sclerosis to erosion of bone in different regions. The management of these diseases will benefit from a deeper understanding of the local versus systemic effects, the relation to the equilibrium of the bone balance (i.e., bone formation versus bone resorption), and the physiological and pathophysiological phenotypes of the cells involved (e.g., osteoblasts, osteoclasts, osteocytes and chondrocytes). For example, the process of endochondral bone formation in chondrocytes occurs exists during skeletal development and healthy conditions, but also in pathological conditions. This review focuses on the complex molecular and cellular taxonomy of bone in the context of rheumatological diseases that alter bone matrix composition and maintenance, giving rise to different bone turnover phenotypes, and how biomarkers (biochemical markers) can be applied to potentially describe specific bone phenotypic tissue profiles.

The Contributive Role of IGFBP-3 and Mitochondria in Synoviocyte-Induced Osteoarthritis through Hypoxia/Reoxygenation Injury: A Pathogenesis-Focused Literature Review

Osteoarthritis (OA), one of the most common joint disorders, is characterized by chronic progressive cartilage degradation, osteophyte formation, and synovial inflammation. OA lesions are not only located in articular cartilage but also in the entire synovial joint. Nevertheless, most of the early studies done mostly focused on the important role of chondrocyte apoptosis and cartilage degeneration in the pathogenesis and progress of OA. The increased expression of hypoxia-inducible factors (HIF-1α and HIF-2α) is known to be the cellular and biochemical signal that mediates the response of chondrocytes to hypoxia. The role of the synovium in OA pathogenesis had been poorly evaluated. Being sensitive to hypoxia/reoxygeneration (H/R) injury, fibroblast-like synoviocytes (FLS) play an essential role in cartilage degradation during the course of this pathology. Insulin-like growth factor binding protein 3 (IGFBP-3) acts as the main carrier of insulin-like growth factor I (IGF-I) in the circulation and remains the most abundant among the six IGFBPs. Synovial fluids of OA patients have markedly increased levels of IGFBP-3. We aim to discuss the interconnected behavior of IGFBP-3 and synoviocytes during the course of osteoarthritis pathogenesis, especially under the influence of hypoxia-inducible factors. In this review, we present information related to the essential role that is played by IGFBP-3 and mitochondria in synoviocyte-induced osteoarthritis through H/R injury. Little research has been done in this area. However, strong evidences show that the level of IGFBP-3 in synovial fluid significantly increased in OA, inhibiting the binding of IGF-1 to IGFR 1 (IGF receptor-1) and therefore the inhibition of cell proliferation. To the best of our knowledge, this is the first paper providing a comprehensive explanatory contribution of IGFBP-3 and mitochondria in synovial cell-induced osteoarthritis through hypoxia/reoxygenation mechanism.

Pattern of thoracic osteophytes development and the association between calcification of the aorta and thoracic osteophytes: CT study

INTRODUCTION

Our aim was use state-of-the-art computed tomography (CT) to assess the prevalence and size of osteophytes in the thoracic spine; the effect of the thoracic aorta on osteophyte development; and the relationship between thoracic aortic calcification and osteophytes.

METHODS

Thoracic CT scans of 100 individuals taken at the T4-T12 spinal levels were examined to determine the numbers and sizes of osteophytes on the right/left side of the vertebrae. Calcific deposits in the thoracic aorta (TAC) at each thoracic vertebral level were assessed. The mean length of the thoracic osteophytes on each side, the total thoracic osteophyte score (TTOS), and the numbers of osteophytes were calculated.

RESULTS

The sample comprised 44 males/56 females (mean age 66.45 ± 9.37). TAC was observed in 54 subjects. Osteophytes were significantly larger on the right side than the left at each spinal level. The largest osteophytes on both sides were at the T9, T10, and T11 levels. After adjustment for age, no significant association was found between sex and TTOS on the left (F = 0.277, p = .600) or right (F = 3.856, p = .052). The right TTOS was significantly associated with TAC after adjustment for age and sex (p = .018).

CONCLUSIONS

Osteophytes in the thoracic spine are prevalent in older adults, with number and size increasing with age in both sexes. Osteophytes are significantly less prominent on the left side than the right, probably because of the proximity of the aorta. TTOS and TAC occurred in the same individuals after adjustment for age and sex, suggesting a possible common etiology.

Turning the Page in Osteoarthritis Assessment with the Use of Ultrasound

PURPOSE OF REVIEW

This narrative review summarizes the last 5 years of published, peer-reviewed research on the use of musculoskeletal ultrasound (US) in osteoarthritis (OA).

RECENT FINDINGS

Multiple features relevant to OA can be visualized on US, including synovitis, erosion, enthesitis, osteophytes, cartilage damage, meniscal extrusion, and popliteal cysts. US can be used to confirm a diagnosis of OA or make an alternate diagnosis in the clinical setting. When a standardized protocol is used, US is a reliable modality for assessment of the features of OA. Findings on US can predict progression and response to therapy in OA of the hand and knee and can allow characterization of risk factors in a cost-effective, non-invasive, repeatable manner. US is becoming more widely used in OA imaging and has clear value in addition to radiography and clinical assessment. US will likely prove useful in defining phenotypes and providing treatment guidance in OA.

Osteoarthritis – a problematic skeletal trait in past human populations. Osteoarthritic changes vs. entheseal changes in the late medieval and early modern population form Łekno

According to medical knowledge, physical activity plays a role in osteoarthritic changes formation. The impact of occupation on osteoarthritic changes development in past human populations is not clear enough, causing problems with interpretation. The aim of the current study is to examine the relationship between osteoarthritis and entheseal changes. Skeletal material comes from the late medieval, early modern population from Łekno (Poland). The sample consists of 110 males and 56 females (adults only). Osteophytes, porosity and eburnation were analyzed in the shoulder, elbow, wrist, hip, knee, and ankle. Entheses on the humerus, radius, femur, and tibia were examined. Standard ranked categorical scoring systems were used for the osteoarthritic and entheseal changes examination.

Males with more developed osteophytes in the shoulder have more “muscular” upper limbs (higher values of muscle markers). Males with more developed osteophytes in the hip and knee are predicted to have more “muscular” lower limbs. Males with more developed osteoarthritis in the shoulder, wrist, hip, and knee exhibit more developed entheseal changes. Males with more developed entheses tend to yield more developed osteophytes (all joints taken together) and general osteoarthritis (all changes and all joints taken together). Females with more developed entheses have more developed osteoarthritis in the elbow, wrist, and hip. Individuals with more developed entheses have much more developed osteophytes. When all the three types of changes are taken together, more “muscular” females exhibit more developed osteoarthritis. The lack of uniformity of the results, wild discussions on the usage of entheses in activity patterns reconstruction and other limitations do not allow to draw unambiguous conclusions about the impact of physical activity on the osteoarthritis in past populations and further studies are needed.

Osteoarthritis: A problematic disease in past human populations. A dependence between entheseal changes, body size, age, sex, and osteoarthritic changes development

Osteoarthritis is a problematic trait in terms of etiology and interpretation in past human populations. The relationships between osteoarthritic changes (osteophytes, porosity, and eburnation) and entheseal changes, body mass, stature, bone massiveness, sex, and age on the basis of skeletal material from Łekno (Poland) are analyzed here. Entheses were the strongest contributor to the prediction of osteophyte expression and when all types of changes and all joints were taken together. Stature demonstrates a negative dependence on porosity. When each joint was analyzed separately, entheses were the strongest contributor to the prediction of arthritis expression in the wrist and hip. Age was the strongest contributor to the prediction of arthritis expression in the elbow. Body mass, stature, bone massiveness, and sex had no effect on osteoarthritic changes in any of the examined joints. The results of the present study suggest an important dependence between entheses and osteoarthritic changes. Other factors had little to no effect on differences in OA severity. These results do not dispel all doubts but enrich knowledge about the effect of etiological factors on osteoarthritic change formation. This knowledge is essential for proper, reliable interpretation of osteoarthritic changes in the context of past human biology, ecology, and behavior.

The relationship of age, activity, and body size on osteoarthritis in weight-bearing skeletal regions

This study examined the simultaneous impact of multiple underlying factors on OA expression in weight-bearing joints of the vertebrae and lower limb of a modern European skeletal sample (Lisbon and Sassari). OA was evaluated using standard ranked categorical scoring; composite OA scores derived through principal component analysis. Body size was calculated from postcranial measurements; torsional strength (J) of the femoral midshaft was calculated from three-dimensional surface models, size standardized and used as a proxy for activity. A standard multiple regression was applied. In all regions, the linear combination of age, body mass, stature, and J was significantly related to differences in OA. Across all joints, age was the strongest predictor; neither body size, nor activity variables demonstrated a statistical relationship with OA at the lumbar or knee; J demonstrated a negative correlation with pelvic OA. Variation in OA can be explained by age, stature, body mass, and structural adaptation related to habitual use. The negative correlation between femoral torsional strength with OA suggests that long-term, repetitive physical work capacity in childhood may be protective against OA development later in life. The multifactorial aetiology of OA requires incorporating multiple lines of evidence to interpret individual or population health from bone samples.

Exploring the Key Genes and Pathways of Osteoarthritis in Knee Cartilage in a Rat Model Using Gene Expression Profiling

PURPOSE

To compare differentially expressed genes (DEGs) mediating osteoarthritis (OA) in knee cartilage and in normal knee cartilage in a rat model of OA and to identify their impact on molecular pathways associated with OA.

MATERIALS AND METHODS

A gene expression profile was downloaded from the Gene Expression Omnibus database. Analysis of DEGs was carried out using GEO2R. Enrichment analyses were performed on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway using the Search Tool for the Retrieval of Interacting Genes database (http://www.string-db.org/). Subsequently, the regulatory interaction network of OA-associated genes was visualized using Cytoscape software (version 3.4.0; www.cytoscape.org).

RESULTS

In the gene expression profile GSE103416, a total of 99 DEGs were identified. Among them, 76 DEGs (76.77%) were overexpressed, and the remaining 23 DEGs (23.23%) were underexpressed. GO and pathway enrichment analyses of target genes were performed. Using gene-gene interaction network analysis, relevant core genes, including MET, UBB, GNAI3, and GNA13, were shown to hold a potential relationship with the development of OA in cartilage. Using quantitative real-time PCR, the Gna13/cGMP-PKG signaling pathway was identified as a potential research target for therapy and for further understanding the development of OA.

CONCLUSION

The results of the present study provide a comprehensive understanding of the roles of DEGs in knee cartilage in relation to the development of OA.

RETRACTED: Tanshinone IIA protects murine chondrogenic ATDC5 cells from lipopolysaccharide-induced inflammatory injury by down-regulating microRNA-203a

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. Concerns were raised about the background pattern of the Western Blots from Figures 3 and 5-7. Given the comments of Dr Elisabeth Bik regarding this article “This paper belongs to a set of over 400 papers (as per February 2020) that share very similar Western blots with tadpole-like shaped bands, the same background pattern, and striking similarities in title structures, paper layout, bar graph design, and - in a subset - flow cytometry panels”, the journal requested the authors to provide the raw data. However, the authors were not able to provide raw data of sufficient quality and detail for the journal to independently audit the provenance and validity of the data, and therefore the Editor-in-Chief decided to retract the article.

Can osteophytes be used as age at death estimators? Testing correlations in skeletonized human remains with known age-at-death

Age-at-death estimation is one of the major challenges when establishing an adult skeleton biological profile. The presence of degenerative joint changes - e.g. osteophytes - has been regarded as a good postmaturity age indicator. This study assessed if a clear relationship between age and osteophytes exists. To accomplish this goal, a total of 16 joint surfaces, from the shoulder, elbow, wrist, hip, knee, and ankle, were examined in 604 adult individuals, of both sexes from two Portuguese Identified collections. Individuals had between 20 and 98 year old at death. Statistically significant results were found between age-at-death and degrees of severity of osteophytes throughout all the articular surfaces analyzed (p>0.001). However, the strength of the correlation varies from moderate to low in the majority of the joints, for both sexes. The only strong correlation effects (r=0.567 in females and r=0.552 in males) were found associated with the left and right glenoid cavity in females and males respectively. More noticeable changes were consistently found in association with older individuals (>62 years old). Results indicate that significant relationships exist between age and the presence of osteophytes in the joint margins. However, correlation effects were low to moderate in most cases, therefore the use of osteophytes to predict age-at-death is not without significant error of interpretation.

MRI-based hip cartilage measures in osteoarthritic and non-osteoarthritic individuals: a systematic review

Osteoarthritis is a common hip joint disease, involving loss of articular cartilage. The prevalence and prognosis of hip osteoarthritis have been difficult to determine, with various clinical and radiological methods used to derive epidemiological estimates exhibiting significant heterogeneity. MRI-based methods directly visualise hip joint cartilage, and offer potential to more reliably define presence and severity of osteoarthritis, but have been underused. We performed a systematic review of MRI-based estimates of hip articular cartilage in the general population and in patients with established osteoarthritis, using MEDLINE, EMBASE and SCOPUS current to June 2016, with search terms such as ‘hip’, ‘femoral head’, ‘cartilage’, ‘volume’, ‘thickness’, ‘MRI’, etc. Ultimately, 11 studies were found appropriate for inclusion, but they were heterogeneous in osteoarthritis assessment methodology and composition. Overall, the studies consistently demonstrate the reliability and potential clinical utility of MRI-based estimates. However, no longitudinal data or reference values for hip cartilage thickness or volume have been published, limiting the ability of MRI to define or risk-stratify hip osteoarthritis. MRI-based techniques are available to quantify articular cartilage signal, volume, thickness and defects, which could establish the sequence and rate of articular cartilage changes at the hip that yield symptomatic osteoarthritis. However, prevalence and rates of progression of hip osteoarthritis have not been established in any MRI studies in the general population. Future investigations could fill this important knowledge gap using robust MRI methods in population-based cross-sectional and longitudinal studies.

Shape variability of the adult human acetabulum and acetabular fossa related to sex and age by geometric morphometrics. Implications for adult age estimation

This study aims to explore shape variability of the acetabulum during the human adult life span, in relation to sex and age. The human acetabular shape was analysed in 682 os coxae from three different documented skeletal collections from the Iberian Peninsula. Two landmarks and thirty-two sliding semi-landmarks were used for the geometric morphometric procedures and a clock-wise standard was used for orientation. The 180° meridian (6:00) line was positioned over the midpoint of the acetabular notch and 36 reference points in 10° increments along the rim were marked. Data showed that size, sex and age significantly influence acetabular shape variation. Sex differences were significant in individuals younger than 65 years old and were characterised by males exhibiting relatively extended acetabular rim profiles from 10:00 to 1:00, narrower acetabular notches, and reduced acetabular fossae. In addition, three main age-related changes occurred to the acetabular shape in both sexes: outer acetabular profile modification, with extension from 10:00 to 1:00 and reduction from 7:00 to 9:00, acetabular notch narrowing, and acetabular fossa reduction. The age-related changes that were observed are shared by both sexes and seem to be related to bone production associated with age. Specifically, age appears to affect the entire border of the lunate surface: the acetabular rim, both acetabular horns, and the outer edge of the acetabular fossa. Furthermore, shape data confirmed the clover-leaf shape of the acetabular fossa in both males and females. These results improve our understanding of acetabular shape, and assist in refining age-estimation methods and enhancing hip surgery and rehabilitation.

Principal component analysis in the evaluation of osteoarthritis

OBJECTIVES

The purpose of this study is to demonstrate advantages of principal component analysis (PCA) as a standardized procedure in the evaluation of osteoarthritis (OA) in a skeletal series to: (1) compute aggregate scores for joint complexes that accurately capture pathological expression, (2) reveal which variables describe the most sample variation in OA, (3) enable inter- and intra-sample comparison of results, and (4) formulate predictive models from component-based arthritic scores.

MATERIALS AND METHODS

The sample (144 males, 145 females) is drawn from a large skeletal cemetery collection of modern Europeans of known sex, age, and occupation. OA data was collected using standard ranked categorical scoring. PCA was conducted separately on lumbar spine, pelvis, and knee regions to generate composite OA scores from eigenequations of the first and second principal components (PC).

RESULTS

Results demonstrate that as severity in OA increases, so does the distribution of OA within the joint surface. In each region, PCA produced the same general pattern with eburnation scoring driving significant changes in composite OA scores, representing earlier to later stages of cartilage degeneration. The distribution of arthritic traits determined by PCA produced an OA score that quantifies the expression of joint changes in varied biological joint structures from most moveable to least mobile, the final stage being joint fusion. OA scores are most highly variable in the lumbar region for both males and females, as compared to the pelvis and knee.

CONCLUSIONS

PCA is a simple, non-parametric method of extracting relevant information from complex OA datasets and summarizes variation based on correlated multi-attributes to reveal a simplified structure of OA expression. Multivariate techniques like PCA should be used to describe discrete OA samples, and are useful to compute population-specific representative measurements for idiopathic joint OA in a skeletal sample.

Bone-formers and bone-losers in an archaeological population

Objectives

Recent biomedical research suggests that, in modern human populations, individuals may vary in their inherent tendency toward bone formation at skeletal and extra‐skeletal locations. However, the nature of this phenomenon is incompletely understood, and the extent to which it might apply to past populations is unclear. It is hypothesized that if there is inter‐individual variation in some overall tendency toward bone formation in skeletal and extra‐skeletal sites then there should be a positive relationship between ligamentous ossification and thickness of cortical bone. This work is a test of this hypothesis in an archaeological population.

Materials and Methods

The study material comprises adult skeletons (N = 137 individuals) of documented age at death from 18th to 19th century London. It examines the relationship between bone deposition in the anterior longitudinal ligament (ALL) in the thoracic spine and cortical index (CI) at the metacarpal measured by radiogrammetry.

Results

Controlling for the potential confounders age, sex, skeletal completeness, occupation (males) and parity (females), there was a positive association between ossification into the ALL and CI. This reflects lesser medullary cavity width in those showing ALL ossification.

Discussion

Ligamentous ossification in the axial skeleton and peripheral cortical bone status are linked, individuals with ALL ossification showing lesser resorption of cortical bone at the endosteal surface. This is consistent with the idea of inter‐individual variation in some general bone‐forming/bone‐losing tendency in this 200 year old study population, but there was no evidence of a link between ALL ossification and increased skeletal subperiosteal bone deposition. Am J Phys Anthropol 159:577–584, 2016. © 2015 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc.

Alpha C-telopeptide of type I collagen is associated with subchondral bone turnover and predicts progression of joint space narrowing and osteophytes in osteoarthritis

OBJECTIVE

To evaluate joint tissue remodeling using the urinary collagen biomarkers urinary α-C-telopeptide of type I collagen (α-CTX) and urinary C-telopeptide of type II collagen (CTX-II) and to determine the association of these biomarkers with osteoarthritis (OA) severity, progression, and localized knee bone turnover.

METHODS

Participants (n = 149) with symptomatic and radiographic knee OA underwent fixed-flexion knee radiography at baseline and 3 years, and late-phase bone scintigraphy of both knees at baseline, which were scored semiquantitatively for osteophyte and joint space narrowing (JSN) severity and uptake intensity, with scores summed across knees. Urinary concentrations of α-CTX and CTX-II were determined by enzyme-linked immunosorbent assay. Immunohistochemical analysis of human OA knees was performed to localize the joint tissue origin of the biomarker epitopes.

RESULTS

Urinary α-CTX concentrations correlated strongly with the intensity of bone scintigraphic uptake and with JSN progression (risk ratio 13.2) and osteophyte progression (risk ratio 3). Urinary CTX-II concentrations were strongly associated with intensity of bone scintigraphic uptake, with JSN and osteophyte severity, and with OA progression based on osteophyte score. Urinary α-CTX localized primarily to high bone turnover areas in subchondral bone. CTX-II localized to the bone-cartilage interface, the tidemark, and damaged articular cartilage.

CONCLUSION

Baseline urinary α-CTX, which was localized to high turnover areas of subchondral bone, was associated with dynamic bone turnover of knees, as signified by scintigraphy, and progression of both osteophytes and JSN. Urinary CTX-II correlated with JSN and osteophyte severity and progression of osteophytes. To our knowledge, this represents the first report of serologic markers reflecting subchondral bone turnover. These collagen markers may be useful for noninvasive detection and quantification of active subchondral bone turnover and joint remodeling in knee OA.

Osteophytes, enthesophytes, and high bone mass: a bone-forming triad with potential relevance in osteoarthritis

Objective

Previous studies of skeletal remains have suggested that both enthesophytes and osteophytes are manifestations of an underlying bone-forming tendency. A greater prevalence of osteophytes has been observed among individuals with high bone mass (HBM) compared with controls. This study was undertaken to examine the possible interrelationships between bone mass, enthesophytes, and osteophytes in a population of individuals with extreme HBM.

Methods

Cases of HBM (defined according to bone mineral density [BMD] Z scores on dual x-ray absorptiometry) from the UK-based HBM study were compared with a control group comprising unaffected family members and general population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs from cases and controls were pooled and evaluated, in a blinded manner, by a single observer, who performed semiquantitative grading of the radiographs for the presence and severity of osteophytes and enthesophytes (score range 0–3 for each). Logistic regression analysis was used to identify significant associations, with a priori adjustment for age, sex, and body mass index.

Results

In this study, 226 radiographs from HBM cases and 437 radiographs from control subjects were included. Enthesophytes (grade ≥1) and moderate enthesophytes (grade ≥2) were more prevalent in HBM cases compared with controls (adjusted odds ratio [OR] 3.00 [95% confidence interval (95% CI) 1.96–4.58], P < 0.001 for any enthesophyte; adjusted OR 4.33 [95% CI 2.67–7.02], P < 0.001 for moderate enthesophytes). In the combined population of cases and controls, the enthesophyte grade was positively associated with BMD at both the total hip and lumbar spine (adjusted P for trend < 0.001). In addition, a positive association between osteophytes and enthesophytes was observed; for each unit increase in enthesophyte grade, the odds of any osteophyte being present were increased >2-fold (P < 0.001).

Conclusion

Strong interrelationships were observed between osteophytes, enthesophytes, and HBM, which may be helpful in defining a distinct subset of patients with osteoarthritis characterized by excess bone formation.

Differentiation between osteoarthritis and psoriatic arthritis: implications for pathogenesis and treatment in the biologic therapy era

Rheumatologists have long considered OA and PsA as two completely distinct arthropathies. This review highlights how some forms of generalized OA and PsA may afflict the same entheseal-associated anatomical territories. While degeneration or inflammation may be clearly discernible at the two extremes, there may be a group of patients where differentiation is impossible. Misdiagnosis of a primary degeneration-related pathology as being part of the PsA spectrum could lead to apparent failure of disease-modifying agents, including apparent anti-TNF and apparent IL23/17 axis therapy failure. This is not a reflection of poor clinical acumen, but rather a failure to appreciate that the pathological process overlaps in the two diseases. Whether the category of OA-PsA overlap disease exists or whether it represents the co-occurrence of two common arthropathies that afflict the same anatomical territories has implications for the optimal diagnosis and management of both OA and PsA.

Prevalence of radiographic hip osteoarthritis is increased in high bone mass

OBJECTIVE

Epidemiological studies have shown an association between increased bone mineral density (BMD) and osteoarthritis (OA), but whether this represents cause or effect remains unclear. In this study, we used a novel approach to investigate this question, determining whether individuals with High Bone Mass (HBM) have a higher prevalence of radiographic hip OA compared with controls.

DESIGN

HBM cases came from the UK-based HBM study: HBM was defined by BMD Z-score. Unaffected relatives of index cases were recruited as family controls. Age-stratified random sampling was used to select further population controls from the Chingford and Hertfordshire cohort studies. Pelvic radiographs were pooled and assessed by a single observer blinded to case-control status. Analyses used logistic regression, adjusted for age, gender and body mass index (BMI).

RESULTS

530 HBM hips in 272 cases (mean age 62.9 years, 74% female) and 1702 control hips in 863 controls (mean age 64.8 years, 84% female) were analysed. The prevalence of radiographic OA, defined as Croft score ≥3, was higher in cases compared with controls (20.0% vs 13.6%), with adjusted odds ratio (OR) [95% CI] 1.52 [1.09, 2.11], P = 0.013. Osteophytes (OR 2.12 [1.61, 2.79], P < 0.001) and subchondral sclerosis (OR 2.78 [1.49, 5.18], P = 0.001) were more prevalent in cases. However, no difference in the prevalence of joint space narrowing (JSN) was seen (OR 0.97 [0.72, 1.33], P = 0.869).

CONCLUSIONS

An increased prevalence of radiographic hip OA and osteophytosis was observed in HBM cases compared with controls, in keeping with a positive association between HBM and OA and suggesting that OA in HBM has a hypertrophic phenotype.

Anti-inflammatory effects of hydrophilic and lipophilic statins with hyaluronic acid against LPS-induced inflammation in porcine articular chondrocytes

The objective of the study is to understand the therapeutic effects of lipophilic (simvastatin) and hydrophilic statins (pravastatin) combined with/without hyaluronic acid for osteoarthritis by an in vitro LPS-induced inflammatory model of articular chondrocytes. HA in combination with different doses of simvastatin or pravastatin were used. Beside cytotoxicity, the influence of statins on NO production, pro-inflammatory cytokine, inflammatory mediators, and NF-κB p50 protein were analyzed. Finally, TUNEL assay was performed to detect DNA strand breakage. Two statins were less able to lower NF-κB activity when they were administrated along without HA. The gene expression demonstrates that simvastatin and pravastatin had the ability to decrease pro-inflammatory and inflammatory mediator levels. High dose simvastatin with or without HA down regulated inflammatory cytokines, but resulted in higher cytotoxicity. TUNEL assay confirms the regulatory effect of statins with or without HA over the apoptosis of chondrocytes, especially in hydrophilic statins. The significant down-regulation of inflammatory mediators suggests that intra-articular injection of HA in combination with statins might feasibly slow the progress of osteoarthritis. Administration of simvastatin or pravastatin with hyaluronic acid may produce beneficial effects for OA treatment, but with better results when hydrophilic statin was used.

The coupling of bone and cartilage turnover in osteoarthritis: opportunities for bone antiresorptives and anabolics as potential treatments?

Osteoarthritis (OA) is the most common form of arthritic disease, and a major cause of disability and impaired quality of life in the elderly. OA is a complex disease of the entire joint, affecting bone, cartilage and synovium that thereby presents multiple targets for treatment. This manuscript will summarise emerging observations from cell biology, preclinical and preliminary clinical trials that elucidate interactions between the bone and cartilage components in particular. Bone and cartilage health are tightly associated. Ample evidence has been found for bone changes during progression of OA including, but not limited to, increased turnover in the subchondral bone, undermineralisation of the trabecular structure, osteophyte formation, bone marrow lesions and sclerosis of the subchondral plate. Meanwhile, a range of investigations has shown positive effects on cartilage health when bone resorption is suppressed, or deterioration of the cartilage when resorption is increased. Known bone therapies, namely oestrogens, selective oestrogen receptor modifiers (SERMs), bisphosphonates, strontium ranelate, calcitonin and parathyroid hormone, might prove useful for treating two critical tissue components of the OA joint, the bone and the cartilage. An optimal treatment for OA likely targets at least these two tissue components. The patient subgroups for whom these therapies are most appropriate have yet to be fully defined but would likely include, at a minimum, those with high bone turnover.

Joint and bone assessment in hand osteoarthritis

Hand osteoarthritis (OA) is a common disease frequently affecting middle-aged women. Prevalence estimates for OA vary widely depending on the age and sex of the population studied, the assessment tools used, and the specific joint sites analyzed OA is characterized by the degradation of articular cartilage, subchondral bone changes and osteophyte formation at the joint margins leading to joint failure. The pathogenesis of the disease and its evolution are multifactorial involving biomechanical, metabolic, hormonal, and genetic factors. Moreover, the role of inflammation has recently been advanced as pivotal in OA onset and progression. In particular, an uncommon variant of hand OA, erosive hand OA, is characterized by inflammatory and degenerative interphalangeal proximal and distal joints. The diagnosis of different types of hand OA is centered on clinical and laboratory investigations which can distinguish the peculiar aspects of these forms. Joint and bone assessments in hand OA are widely studied but there is no agreement with regard to established parameters to make a definitive diagnosis. This report focuses on the laboratory and clinimetric assessments that can be used to distinguish hand OA subtypes and addresses the debatable association with low bone mineral density in osteoporosis.

CCN family member 2/connective tissue growth factor (CCN2/CTGF) has anti-aging effects that protect articular cartilage from age-related degenerative changes

To examine the role of connective tissue growth factor CCN2/CTGF (CCN2) in the maintenance of the articular cartilaginous phenotype, we analyzed knee joints from aging transgenic mice (TG) overexpressing CCN2 driven by the Col2a1 promoter. Knee joints from 3-, 14-, 40-, and 60-day-old and 5-, 12-, 18-, 21-, and 24-month-old littermates were analyzed. Ccn2-LacZ transgene expression in articular cartilage was followed by X-gal staining until 5 months of age. Overexpression of CCN2 protein was confirmed through all ages in TG articular cartilage and in growth plates. Radiographic analysis of knee joints showed a narrowing joint space and other features of osteoarthritis in 50% of WT, but not in any of the TG mice. Transgenic articular cartilage showed enhanced toluidine blue and safranin-O staining as well as chondrocyte proliferation but reduced staining for type X and I collagen and MMP-13 as compared with those parameters for WT cartilage. Staining for aggrecan neoepitope, a marker of aggrecan degradation in WT articular cartilage, increased at 5 and 12 months, but disappeared at 24 months due to loss of cartilage; whereas it was reduced in TG articular cartilage after 12 months. Expression of cartilage genes and MMPs under cyclic tension stress (CTS) was measured by using primary cultures of chondrocytes obtained from wild-type (WT) rib cartilage and TG or WT epiphyseal cartilage. CTS applied to primary cultures of mock-transfected rib chondrocytes from WT cartilage and WT epiphyseal cartilage induced expression of Col1a1, ColXa1, Mmp-13, and Mmp-9 mRNAs; however, their levels were not affected in CCN2-overexpressing chondrocytes and TG epiphyseal cartilage. In conclusion, cartilage-specific overexpression of CCN2 during the developmental and growth periods reduced age-related changes in articular cartilage. Thus CCN2 may play a role as an anti-aging factor by stabilizing articular cartilage.

Hand osteoarthritis and bone loss: is there an inverse relationship?

An inverse relationship between osteoarthritis (OA) and bone loss has been supported in clinical research, but there has been little research on bioarchaeological skeletal remains. The current study examines 115 adults from a prehistoric hunter-gatherer population to aid in determining whether hand OA and bone loss are negatively correlated. OA lipping is scored on a four-point scale on left and right trapezia, MC1s, and MC2s and then analyzed with regard to their relationships with sex, age, right MC2 cortical index, and left and right MC1 robusticity, midshaft circumference, and midshaft diameter values. With sexes and ages combined, higher OA scores are found in individuals with greater midshaft diameters. However, lower cortical indices were found in individuals with higher right MC2 OA scores. The data presented tenuously support that bone loss is lower in individuals with more severe osteoarthritis, but age-related changes in bone deposition may make cortical index and other external shaft dimensions an unsuitable variable to examine this relationship.

Periarticular osteophytes as an appendicular joint stress marker (JSM): analysis in a contemporary Japanese skeletal collection

Objective

The aim of this study was to investigate the possibility that periarticular osteophytes plays a role as a appendicular joint stress marker (JSM) which reflects the biomechanical stresses on individuals and populations.

Methods

A total of 366 contemporary Japanese skeletons (231 males, 135 females) were examined closely to evaluate the periarticular osteophytes of six major joints, the shoulder, elbow, wrist, hip, knee, and ankle and osteophyte scores (OS) were determined using an original grading system. These scores were aggregated and analyzed statistically from some viewpoints.

Results

All of the OS for the respective joints were correlated logarithmically with the age-at-death of the individuals. For 70 individuals, in whom both sides of all six joints were evaluated without missing values, the age-standardized OS were calculated. A right side dominancy was recognized in the joints of the upper extremities, shoulder and wrist joints, and the bilateral correlations were large in the three joints on the lower extremity. For the shoulder joint and the hip joint, it was inferred by some distinctions that systemic factors were relatively large. All of these six joints could be assorted by the extent of systemic and local factors on osteophytes formation. Moreover, when the age-standardized OS of all the joints was summed up, some individuals had significantly high total scores, and others had significantly low total scores; namely, all of the individuals varied greatly in their systemic predisposition for osteophytes formation.

Conclusions

This study demonstrated the significance of periarticular osteophytes; the evaluating system for OS could be used to detect differences among joints and individuals. Periarticular osteophytes could be applied as an appendicular joint stress marker (JSM); by applying OS evaluating system for skeletal populations, intra-skeletal and inter-skeletal variations in biomechanical stresses throughout the lives could be clarified.

High bone mass is associated with an increased prevalence of joint replacement: a case-control study

Objective. Epidemiological studies have shown an association between OA and increased BMD. To explore the nature of this relationship, we examined whether the risk of OA is increased in individuals with high bone mass (HBM), in whom BMD is assumed to be elevated due to a primary genetic cause.

Methods. A total of 335 115 DXA scans were screened to identify HBM index cases (defined by DXA scan as an L1 Z-score of ≥+3.2 and total hip Z-score ≥+1.2, or total hip Z-score ≥+3.2 and L1 Z-score ≥+1.2). In relatives, the definition of HBM was L1 Z-score plus total hip Z-score ≥+3.2. Controls comprised unaffected relatives and spouses. Clinical indicators of OA were determined by structured assessment. Analyses used logistic regression adjusting for age, gender, BMI and social deprivation.

Results. A total of 353 HBM cases (mean age 61.7 years, 77% female) and 197 controls (mean age 54.1 years, 47% female) were included. Adjusted NSAID use was more prevalent in HBM cases versus controls [odds ratio (OR) 2.17 (95% CI 1.10, 4.28); P = 0.03]. The prevalence of joint replacement was higher in HBM cases (13.0%) than controls (4.1%), with an adjusted OR of 2.42 (95% CI 1.06, 5.56); P = 0.04. Adjusted prevalence of joint pain and knee crepitus did not differ between cases and controls.

Conclusion. HBM is associated with increased prevalence of joint replacement surgery and NSAID use compared with unaffected controls.

Natural course in tennis elbow--lateral epicondylitis after all?

Tennis elbow is a common and difficult-to-treat condition largely because of lack of evidence. The natural history is unknown, but the condition is described as self-limiting. The objective of this case report is to describe the natural course of two control participants (pain free), who later developed tennis elbow, patient history, clinical findings, and ultrasound and colour Doppler examination before, during and after a period of tennis elbow.

Osteochondral alterations in osteoarthritis

Osteoarthritis (OA) is a major cause of pain and disability in the aging population, but its pathogenesis remains incompletely understood. Alterations beneath the articular cartilage at the osteochondral junction are attracting interest as possible mediators of pain and structural progression in OA. Osteochondral changes occur early during the development of OA and may aggravate pathology elsewhere in the joint. Loss of osteochondral integrity removes the barrier between intra-articular and subchondral compartments, exposing subchondral bone and its nerves to abnormal chemical and biomechanical influence. Osteochondral plasticity results in a merging of tissue compartments across the junction. Loss of the clearly differentiated demarcation between bone and articular cartilage is associated with invasion of articular cartilage by blood vessels and sensory nerves, and advancing endochondral ossification. Increased subchondral bone turnover is intimately associated with these alterations at the osteochondral junction. Cells signal across the osteochondral junction, and this cross-talk may be both a consequence of, and contribute to these pathological changes. Bone turnover, angiogenesis and nerve growth are also features of other diseases such as osteoporosis and cancers, for which therapeutic interventions are already advanced in their development. Here we review pathological changes at the osteochondral junction and explore their potential therapeutic implications for OA. This article is part of a Special Issue entitled "Osteoarthritis".

Molecular analysis of age and sex-related gene expression in meniscal tears with and without a concomitant anterior cruciate ligament tear

BACKGROUND

The meniscus plays critical roles in the knee, contributing to load transmission, shock absorption, and joint stability. Little is known about gene expression in meniscal tears, particularly in relation to injury pattern and patient age and sex. The purpose of this study was to test the hypothesis that gene expression in meniscal tears varies depending on patient age and sex and whether the anterior cruciate ligament (ACL) is also torn.

METHODS

Meniscal tissue from twenty-eight patients with an isolated meniscal tear or a meniscal tear with a concomitant ACL tear was collected at the time of clinically indicated partial meniscectomy. Messenger RNA (mRNA) expression was examined by quantitative real-time polymerase chain reaction for molecular markers of osteoarthritis including proinflammatory cytokines (interleukin [IL]-1α, IL-1β, IL-6, and tumor necrosis factor-alpha [TNFα]), chemokines (IL-8, CCL3, CCL3L1, CXCL1, CXCL3, CXCL6, and CCL20), aggrecanases (ADAMTS-4 [a disintegrin and metalloproteinase with thrombospondin type-4 motifs] and ADAMTS-5), matrix metalloproteinases (MMP-1, MMP-3, MMP-9, and MMP-13), transcription factors (NFκB2 [nuclear factor kappa B2], NFκBIA [NF-kappa B inhibitor alpha], and IκBA [inhibitor of kappa B alpha]), and matrix components (bone morphogenetic protein [BMP]-2, type-I collagen alpha 1 [Col1a1], Col2a1, and aggrecan).

RESULTS

Expression of IL-1β (p = 0.02), ADAMTS-5 (p = 0.001), MMP-1 (p = 0.007), MMP-9 (p = 0.002), MMP-13 (p = 0.01), and NFκB2 (p = 0.01) was significantly higher in patients with a meniscal tear who were under the age of forty years than it was in those over the age of forty years. Similarly, the expression of ADAMTS-4 (p = 0.002), ADAMTS-5 (p = 0.02), MMP-1 (p = 0.02), and MMP-13 (p = 0.0002) was higher in patients with a meniscal tear and an ACL tear who were under the age of forty years than it was in those over forty years. In patients with a meniscal tear and an ACL tear, the expression of IL-1β (p = 0.01), TNFα (p = 0.02), MMP-13 (p = 0.004), CCL3 (p = 0.03), and CCL3L1 (p = 0.03) was significantly higher, while that of aggrecan (p = 0.03) was lower, than that in patients with a meniscal tear alone. The only sex-based difference in gene expression was higher levels of CCL3L1 in female patients (p &lt; 0.05) of all ages with combined injuries.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings suggest clinically relevant differences in the response of the knee to meniscal tears on the basis of patient age and sex. Elevated expression levels of arthritis-related markers indicate an increased catabolic response in patients under forty years old. Higher expression of catabolic markers in patients with meniscal and ACL tears suggests this combined injury pattern is more likely to lead to the development of osteoarthritis. Catabolic activity in meniscal tissue may predict patients who are at risk for progression of osteoarthritis following partial meniscectomy.

Relation of hand enthesophytes with knee enthesopathy: is osteoarthritis related to a systemic enthesopathy?

OBJECTIVE

Enthesopathy has been reported as a feature of osteoarthritis (OA) in the distal interphalangeal (DIP) joints. We previously reported that central bone marrow lesions (BML) on magnetic resonance imaging (MRI) scans are associated with OA. In this study, we evaluated whether hand and knee enthesopathy were related.

METHODS

We studied knee and hand radiographs of subjects from the Framingham Osteoarthritis Study. Subjects seen in 2002-2005 had bilateral posteroanterior hand radiographs, weight-bearing knee radiographs, and knee MRI scans. Hand radiographs were read for enthesophytes at the juxtaarticular nonsynovial areas of metacarpophalangeal (MCP), proximal interphalangeal (PIP), and DIP joints, and midshafts of the phalanges. We selected 100 cases of knees with central BML and 100 matched controls. Conditional logistic regression was used to assess associations.

RESULTS

Subjects with enthesophytes of at least 1 score ≥ 2 at DIP, PIP, and/or MCP were not more likely to have central knee BML (OR 0.49, 95% CI 0.17-1.40) than those without enthesophytes. Similarly, having at least 1 score ≥ 2 on the shafts was not significantly associated with having a central knee BML (OR 0.59, 95% CI 0.23-1.51). Adjustment for the presence of diabetes mellitus did not affect these results, but there was an increased prevalence of diabetes in those with hand enthesophytes (OR 3.09, 95% 1.29-7.40, enthesophyte score ≥ 2).

CONCLUSION

We found no increase in the prevalence of hand enthesophytes among persons with central knee BML on their knee MRI scans. This provides evidence against a systemic enthesopathic disorder in association with knee OA.

An atypical degenerative osteoarthropathy in Hyp mice is characterized by a loss in the mineralized zone of articular cartilage

Patients with X-linked hypophosphatemia (XLH) develop enthesophytes and osteophytes secondary to articular cartilage degeneration and together are the primary cause of morbidity in adult patients so afflicted. We have previously characterized the enthesopathy in Hyp mice, a murine model of XLH. We now extend these studies to the synovial joint in order to characterize potential cellular changes in articular cartilage that may predispose patients to the osteoarthropathy of XLH. We report that, despite highly elevated levels of alkaline phosphatase activity throughout articular cartilage, there is a complete loss in the mineralized zone of articular cartilage as assessed by von Kossa staining of mineral and as quantified by EPIC-microCT analysis and evidence of vascular invasion. We also identify the downregulation of extracellular matrix (ECM) factors identified as regulators of terminally differentiated mineralizing articular chondrocytes. There is also a striking increase in the histochemical staining of sulfated proteoglycans, a change that may reflect the loss of a transitional tissue that reduces mechanical stress at the interface between cartilage and subchondral bone. The failure of mineralizing articular chondrocytes to develop in the hypophosphatemic state suggests that phosphate may be a key regulator of chondrocyte mineralization. Accordingly, we find that the appropriate zonal arrangement and phenotypic markers of articular cartilage are significantly reestablished by phosphate-replacement therapy. Given the turnover and maintenance of articular cartilage ECM, the identification of early and abnormal cellular changes unique to XLH will undoubtedly aid in a more effective management of this disease to minimize the onset of degenerative osteoarthropathy.

Characterization of an Ex vivo Femoral Head Model Assessed by Markers of Bone and Cartilage Turnover

OBJECTIVE

The pathophysiology of osteoarthritis involves the whole joint and is characterized by cartilage degradation and altered subchondral bone turnover. At present, there is a need for biological models that allow investigation of the interactions between the key cellular players in bone/cartilage: osteoblasts, osteoclasts, and chondrocytes.

METHODS

Femoral heads from 3-, 6-, 9-, and 12-week-old female mice were isolated and cultured for 10 days in serum-free media in the absence or presence of IGF-I (100 nM) (anabolic stimulation) or OSM (10 ng/mL) + TNF-α (20 ng/mL) (catabolic stimulation). Histology on femoral heads before and after culture was performed, and the growth plate size was examined to evaluate the effects on cell metabolism. The conditioned medium was examined for biochemical markers of bone and cartilage degradation/formation.

RESULTS

Each age group represented a unique system regarding the interest of bone or cartilage metabolism. Stimulation over 10 days with OSM + TNF-α resulted in depletion of proteoglycans from the cartilage surface in all ages. Furthermore, OSM + TNF-α decreased growth plate size, whereas IGF-I increased the size. Measurements from the conditioned media showed that OSM + TNF-α increased the number of osteoclasts by approximately 80% and induced bone and cartilage degradation by approximately 1200% and approximately 2600%, respectively. Stimulation with IGF-I decreased the osteoclast number and increased cartilage formation by approximately 30%.

CONCLUSION

Biochemical markers and histology together showed that the catabolic stimulation induced degradation and the anabolic stimulation induced formation in the femoral heads. We propose that we have established an explant whole-tissue model for investigating cell-cell interactions, reflecting parts of the processes in the pathogenesis of joint degenerative diseases.

Matrix metalloproteinases and inhibitors in cartilage tissue engineering

Inhibiting matrix metalloproteinase (MMP) activity has been considered as a potential therapeutic treatment that may modify the outcome for osteoarthritis (OA), a disease governed by abnormalities in the balance between MMPs and their inhibitors. Due to unexpected tissue fibrosis in early-phase clinical trials with some MMP inhibitors, possible divergent effects of inhibiting MMP activity on different cells are hypothesized. Therefore, we evaluated the effects of MMP inhibition on cells relevant to cartilage tissue engineering by culturing them in vitro in poly(ethylene glycol) diacrylate hydrogels to create 3D representations of cartilage tissue while allowing for local and direct administration of inhibitors. Mesenchymal stem cells demonstrated an inhibitor concentration-dependent decrease in extracellular matrix (ECM) deposition, while normal chondrocytes were mainly affected at the highest concentration of inhibitors. In contrast, the concomitant treatment of chondrocytes from patients with OA resulted in an increase in glycosaminoglycan content only in the presence of both inhibitors and anabolic growth factors. The observed upregulation of bone markers, however, indicates a delicate balance that must be addressed to therapeutically treat OA chondrocytes to stimulate more ECM production without errant bone formation. In conclusion, this study suggests that MMPs have complex interactions in both pathobiology and homeostasis.

Osteoarthritis of the distal interphalangeal joint

Osteoarthritis occurs with the highest prevalence in the distal interphalangeal joint of the hand and has been divided into an erosive and a nonerosive form. The pathogenesis of the early stages of osteoarthritis is poorly understood, but considerable emphasis has been placed on the role of cartilage and subchondral bone as well as soft tissue structures such as collateral ligaments and tendons. Radiographic evaluation represents the most standardized method to quantify disease progression, with different systems having been developed for defining and grading radiographic features. This current concepts article examines the recent knowledge base regarding the etiology, pathogenesis, and evaluation of osteoarthritis of the distal interphalangeal joint.

Treatment with TNF-α inhibitor infliximab might reduce hand osteoarthritis in patients with rheumatoid arthritis

OBJECTIVES

To investigate the association between systemic and local inflammation and incident and progressive radiographic secondary osteoarthritis (OA) in interphalangeal joints (IPJs) over 3 years in rheumatoid arthritis (RA) patients and the effect of tumor necrosis factor alpha (TNF-α) inhibitor infliximab on secondary OA in IPJs.

METHODS

In the present observational longitudinal study baseline and 3-year hand X-rays of 416 recent-onset RA patients were scored for osteophytes and erosions in IPJs, blinded for time, using Osteoarthritis Research Society International atlas and Sharp-van der Heijde score. The associations between inflammatory factors and incident and progressive secondary OA in distal IPJs (DIPJs) and proximal IPJs (PIPJs) and the effect of infliximab compared to disease-modifying anti-rheumatic drug treatment on secondary OA were analyzed by multivariable regression and generalised estimating equations analyses.

RESULTS

Sixty-seven percent of the patients were female with, at baseline, a mean age of 54 years and OA present in DIPJs and PIPJs in 37% and 13%. Three years later, new secondary OA in DIPJs and PIPJs was seen in 11% and 10%, and progressive secondary OA in 36% and 35%. High erythrocyte sedimentation rate over 3 years and progressive erosive damage were risk factors for incident secondary OA in DIPJs, but not in PIPJs. At joint level, progression of erosions was associated with both incident and progressive secondary OA, only in DIPJs. Infliximab treatment was associated with lower incident secondary OA in PIPJs [relative risk 0.5 (95% confidence interval 0.2, 1.0)], independent of decrease in inflammation.

CONCLUSION

Incident and progressive secondary OA in DIPJs over 3 years was associated with high inflammatory activity in RA. Infliximab treatment reduced incident secondary OA in PIPJs independent of decrease in inflammation, suggesting that anti-TNF-α therapy might be effective against secondary hand OA via other pathways than suppression of inflammation. Further studies in populations of primary hand OA are necessary to determine the role of anti-TNF-α in treatment of primary hand OA.

Microarchitectural adaptations in aging and osteoarthrotic subchondral bone issues

The human skeleton optimizes its microarchitecture by elaborate adaptations to mechanical loading during development and growth. The mechanisms for adaptation involve a multistep process of cellular mechanotransduction stimulating bone modelling, and remodeling resulting in either bone formation or resorption. This process causes appropriate microarchitectural changes tending to adjust and improve the bone structure to its prevailing mechanical environment. Normal individual reaches peak bone mass at age between 25 and 30 years, and thereafter bone mass declines with age in both genders. The bone loss is accompanied by microarchitectural deterioration resulting in reduced mechanical strength likely leading to fragility fractures. With aging, inevitable bone loss occurs, which is frequently the cause of osteoporosis; and inevitable bone and joint degeneration happens, which often results in osteoarthrosis. These diseases are among the major health care problems in terms of socio-economic costs. The overall goals of the current series of studies were to investigate the age-related and osteoarthrosis (OA) related changes in the 3-D microarchitectural properties, mechanical properties, collagen and mineral quality of subchondral cancellous and cortical bone tissues. The studies included mainly two parts. For human subjects: aging- (I–IV) and early OArelated (V–VI) changes in cancellous bone properties were assessed. For OA guinea pig models (VII–IX), three topics were studied: firstly, the spontaneous, age-related development of guinea pig OA; secondly, the potential effects of hyaluronan on OA subchondral bone tissues; and thirdly, the effects on OA progression of an increase in subchondral bone density by inhibition of bone remodeling with a bisphosphonate. These investigations aimed to obtain more insight into the age-related and OA-related subchondral bone adaptations.

The effect of oral salmon calcitonin delivered with 5-CNAC on bone and cartilage degradation in osteoarthritic patients: a 14-day randomized study

BACKGROUND

The aim of this study was to investigate the pharmacokinetic and pharmacodynamic parameters of oral salmon calcitonin (oSCT) administered over 14 days to men and women presenting with osteoarthritis (OA).

MATERIALS AND METHODS

The study was a phase-I, 2-week, placebo-controlled, double-blind, double-dummy, randomized, gender-stratified study including 73 subjects aged 57-75 years. Patients had painful OA with a Kellgren and Lawrence index score of I-III. Treatment allocations were; 0.6 mg, 0.8 mg of oSCT, or placebo. Treatment was given twice daily for 14 days. The morning dose was administered between 07:00 and 08:00 at least 30 min before breakfast. The second dose was administered 30 min before evening dinner. On treatment day 1 and 14, the morning dose was followed by 5h of fasting, and blood samples and urine were collected immediately prior to dosing and according to the protocol. Study parameters were: plasma sCT levels, bone resorption by CTX-I (serum C-terminal telopeptide of collagen type I), bone formation by osteocalcin (serum OC), and cartilage degradation by CTX-II (urine C-terminal telopeptide of collagen type II) (clinicaltrials.gov identifier: NCT00486369).

RESULTS

Doses of 0.8 mg compared with 0.6 mg produced significantly higher C(max) and AUC(0-4 hrs), of calcitonin, P=0.03. This resulted in significant reductions in CTX-I and CTX-II, [P<0.0001; P=0.007]. No differences were observed between baseline and follow-up at day 14 in pharmacokinetic and pharmacodynamic parameters. Gender had no observable influence on results.

CONCLUSIONS

oSCT given twice daily with a pre-dinner and morning fasting dosing resulted in reductions in markers of bone resorption and cartilage degradation.

Tender point count, pain, and mobility in the older population: the mobilize Boston study

Prevalence of tender points (TP), and widespread pain and fibromyalgia, as well as the relationship between TP and widespread pain and mobility, was examined in 585 community-dwelling older adults (mean age 78.2 years, 63.4% female). Pain was based on location (none, single site, multisite, widespread). Mobility was measured by the Short Physical Performance Battery (SPPB), gait speed, and self-reported (S-R) mobility difficulty. Tender-point count and health characteristics (ie, BMI, chronic conditions, analgesic use, number of medications, depression, and blocks walked per week) were assessed. Several participants had 3 or more TP (22.1%) although prevalence of criteria-based fibromyalgia was low (.3%). Mobility was more limited in persons with higher tender-point counts. After adjustment for pain and other risk factors, higher tender-point count was associated with poorer SPPB performance (score < 10, aOR = 1.09 per TP, 95%CI, 1.01-1.17), and slow gait speed (< .784m/sec, aOR = 1.14 per TP, 95%CI, 1.05-1.24), but not with S-R mobility difficulty. S-R mobility difficulty was associated with more disseminated pain (multisite pain, aOR = 2.01, 95%CI, 1.21-3.34; widespread pain, aOR = 2.47, 95%CI, 1.09-5.62). These findings portray a significant mobility burden related to tender-point count and multisite and widespread pain in the older population. Future studies using longitudinal methods are warranted.

PERSPECTIVE

Higher tender-point count, multisite pain, and widespread pain are common in community-dwelling older adults and associated with mobility problems. Both the manual tender-point exam and the McGill Pain Map may provide important yet different information about risks for mobility disability in older individuals.