Effect of hormone therapy on risk of hip and knee joint replacement in the Women's Health Initiative

Are estrogen-related drugs new alternatives for the management of osteoarthritis?

Osteoarthritis (OA) is a chronic degenerative disease involving multiple physiopathological mechanisms. The increased prevalence of OA after menopause and the presence of estrogen receptors in joint tissues suggest that estrogen could help prevent development of OA. This review summarizes OA research with a focus on the effects of estrogen and selective estrogen receptor modulators (SERMs). Preclinical studies and clinical trials of estrogen therapy have reported inconsistent results. However, almost all studies assessing SERM treatment have obtained more consistent and favorable effects in OA with a relatively safety and tolerability profiles. At present, some SERMs including raloxifene and bazedoxifene have been approved for the treatment of osteoporosis. In summary, estrogen-related agents may exert both a direct effect on subchondral bone and direct and/or indirect effects upon the surrounding tissues, including the articular cartilage, synovium, and muscle, to name a few. Estrogen and SERMs may be particularly favorable for postmenopausal patients with early-stage OA or osteoporotic OA, a phenotype defined by reduced bone mineral density related to high remodeling in subchondral bone. At present, no single drug exists that can prevent OA progression. Although estrogen-related drugs provide insight into the continued work in the field of OA drug administration, further research is required before SERMs can become therapeutic alternatives for OA treatment.

Hand osteoarthritis, menopause and menopausal hormone therapy

Hand osteoarthritis (OA) is one of the commonest musculoskeletal conditions, primarily affecting women over the age of 50, typically around the age of the menopause. Symptomatic disease can give rise to substantial pain, impairment of hand function and quality of life, leading to significant socioeconomic cost. There is currently no disease-modifying therapy, representing a huge unmet clinical need. The evidence for a relationship between hand OA and the menopause is summarised. Whether there is evidence for an effect of menopausal hormonal therapy on the incidence, prevalence or severity of symptomatic hand OA is critically reviewed, and gaps in our knowledge identified. Lastly, the potential mechanisms by which estrogen, or newer agents such as SERMs, might act to interfere with disease pathogenesis are overviewed. The need for specifically designed, controlled trials of agents in cohorts with symptomatic hand OA, refractory to standard symptomatic management is highlighted.

Male and female differences in musculoskeletal disease

Gender differences exist in the presentation of musculoskeletal disease, and recognition of the differences between men and women's burden of disease and response to treatment is key in optimizing care of orthopaedic patients. The role of structural anatomy differences, hormones, and genetics are factors to consider in the analysis of differential injury and arthritic patterns between genders.

Association of single nucleotide polymorphisms in estrogen receptor alpha gene with susceptibility to knee osteoarthritis: a case-control study in a Chinese Han population

Osteoarthritis (OA) is the most prevalent form of arthritis and its multifactorial nature has been increasingly recognized. Genetic factors play an important role in OA etiology and estrogen receptor alpha (ESR1) gene polymorphisms may be involved. This study tried to explore whether the ESR1 gene single nucleotide polymorphisms (SNPs) were associated with primary knee OA in the Chinese Han population. Two SNPs, rs2234693 and rs9340799, were genotyped in 469 cases and 522 controls. Rs2234693 was associated with knee OA in the dominant genetic model (TT + TC versus CC) (P = 0.025) and a higher T allele frequency existed (P = 0.047) among females. The combined genotype (TT + TC) (P = 0.025) and T allele (P = 0.016) were related with mild knee OA only. For rs9340799, A allele was associated with knee OA in all subjects (P = 0.031) and females (P = 0.046). Statistical differences were detected in the dominant genetic model (AA + AG versus GG) among females (P = 0.030). The combined genotype (AA + AG) (P = 0.036) and A allele (P = 0.039) were merely correlated with mild knee OA. ESR1 gene is considerably associated with knee OA etiology in the Chinese Han population.

Role of hormones in cartilage and joint metabolism: understanding an unhealthy metabolic phenotype in osteoarthritis

OBJECTIVE

Joint health is affected by local and systemic hormones. It is well accepted that systemic factors regulate the metabolism of joint tissues, and that substantial cross-talk between tissues actively contributes to homeostasis. In the current review, we try to define a subtype of osteoarthritis (OA), metabolic OA, which is dependent on an unhealthy phenotype.

METHODS

Peer-reviewed research articles and reviews were reviewed and summarized. Only literature readily available online, either by download or by purchase order, was included.

RESULTS

OA is the most common joint disease and is more common in women after menopause. OA is a disease that affects the whole joint, including cartilage, subchondral bone, synovium, tendons, and muscles. The clinical endpoints of OA are pain and joint space narrowing, which is characterized by cartilage erosion and subchondral sclerosis, suggesting that cartilage is a central tissue of joint health. Thus, the joint, more specifically the cartilage, may be considered a target of endocrine function in addition to the well-described traditional risk factors of disease initiation and progression such as long-term loading of the joint due to obesity. Metabolic syndrome affects a range of tissues and may in part be molecularly described as a dysregulation of cytokines, adipokines, and hormones (e.g., estrogen and thyroid hormone). Consequently, metabolic imbalance may both directly and indirectly influence joint health and cartilage turnover, altering the progression of diseases such as OA.

CONCLUSIONS

There is substantial evidence for a connection between metabolic health and development of OA. We propose that more focus be directed to understanding this connection to improve the management of menopausal health and associated comorbidities.

Experimental osteoarthritis models in mice

Osteoarthritis (OA) is a slowly progressing, degenerative disorder of synovial joints culminating in the irreversible destruction of articular cartilage and subchondral bone. It affects almost everyone over the age of 65 and influences life quality of affected individuals with enormous costs to the health care system. Current therapeutic strategies seek to ameliorate pain and increase mobility; however, to date none of them halts disease progression or regenerates damaged cartilage or bone. Thus, there is an ultimate need for the development of new, noninvasive treatments that could substitute joint replacement for late- or end-stage patients. Therefore, osteoarthritis animal models for mimicking of all OA features are important. Mice develop an OA pathology that is comparable to humans, rapidly develop OA due to the short lifetime and show reproducible OA symptoms. They provide a versatile and widely used animal model for analyzing molecular mechanisms of OA pathology. One major advantage over large animal models is the availability of knockout or transgenic mice strains to examine genetic predispositions/contributions to OA.In this chapter, we describe three widely used instability-inducing murine osteoarthritis models. The most common two methods for surgical induction are: (1) destabilization of the medial meniscus (DMM) and (2) anterior cruciate ligament transection (ACLT). In the DMM model, the medial meniscotibial ligament is transected while in the ACLT model the anterior cruciate ligament is destroyed. In the third, chemical induced instability method, intraarticular collagenase is injected into the knee joint. Intraarticular collagenase weakens articular ligaments which cause instability of the joint, and full-blown OA develops within 6 weeks. For morphological evaluation, we correspond mainly to the recommendations of OARSI for histological assessment of osteoarthritis in mouse. For statistical evaluation summed or mean scores of all four knee areas (medial tibial plateau (MTP), medial tibial condyle (MFC), lateral tibial plateau (LTP) or lateral femoral condyle (LFC)), medial and/or lateral regions are used.In future, not only large animal models like guinea pigs, sheep, goats, or horses will be important for a better understanding of osteoarthritis, but especially the mouse model with its rapid development of osteoarthritis and its numerous advantages by providing knockout or transgenic strains will become more and more relevant for drug development and determination of genetic predispositions of osteoarthritis pathology.

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.

An OA phenotype may obtain major benefit from bone-acting agents

BACKGROUND

Osteoarthritis (OA) joints display relevant microstructure alterations associated to an increase in remodeling at subchondral bone, which supports its crucial role in OA pathogenesis. Despite this, the treatment of knee OA patients with antiresorptive drugs has given discordant results, suggesting the existence of a particular patient subset with good response to halting high subchondral remodeling.

OBJECTIVE

To identify an OA phenotype that may obtain major benefit from therapy with bone-acting agents.

METHODS

A systematic review of the literature was performed by searching the Medline and PubMed databases from 1990 to April 2013 using the following keywords: subchondral bone, articular cartilage, and osteoarthritis in various combinations with bone agents, bone mineral density, and scintigraphy.

RESULTS

Early animal and human studies provided the rationale for the beneficial use of bone agents on OA cartilage damage. Several bone-acting agents have reduced low back pain and likely spondylosis progression. Recently, strontium ranelate has been reported to exert both structural and clinical benefits in knee OA patients with radiological progression. However, other antiresorptives have shown divergent results. Human studies suggest that these contradictory results may be due to the lack of well-defined OA phenotypes and an accurate methodology to recruit and follow up these patients.

CONCLUSIONS

A particular subset of postmenopausal patients with high remodeling and/or low subchondral bone density may benefit from the treatment with bone-acting agents hindering OA progression. This OA population could be identified with the simultaneous use of subchondral bone dual-energy X-ray absorptiometry and scintigraphy.

Incidence and risk factors for clinically diagnosed knee, hip and hand osteoarthritis: influences of age, gender and osteoarthritis affecting other joints

OBJECTIVES

Data on the incidence of symptomatic osteoarthritis (OA) are scarce. We estimated incidence of clinical hip, knee and hand OA, and studied the effect of prevalent OA on joint-specific incident OA.

METHODS

SIDIAP contains primary care records for>5 million people from Catalonia (Spain). Participants aged ≥40 years with an incident diagnosis of knee, hip or hand OA between 2006 and 2010 were identified using International Classification of Diseases (ICD)-10 codes. Incidence rates and female-to-male rate ratios (RRs) for each joint site were calculated. Age, gender and body mass index-adjusted HR for future joint-specific OA according to prevalent OA at other sites were estimated using Cox regression.

RESULTS

3 266 826 participants were studied for a median of 4.45 years. Knee and hip OA rates increased continuously with age, and female-to-male RRs were highest at age 70-75 years. In contrast, female hand OA risk peaked at age 60-64 years, and corresponding female-to-male RR was highest at age 50-55 years. Adjusted HR for prevalent knee OA on risk of hip OA was 1.35 (99% CI 1.28 to 1.43); prevalent hip OA on incident knee OA: HR 1.15 (1.08 to 1.23). Prevalent hand OA predicted incident knee and hip OA: HR 1.20 (1.14 to 1.26) and 1.23 (1.13 to 1.34), respectively.

CONCLUSIONS

The effect of age is greatest in the elderly for knee and hip OA, but around the menopause for hand OA. OA clusters within individuals, with higher risk of incident knee and hip disease from prevalent lower limb and hand OA.

Estrogen alone and joint symptoms in the Women's Health Initiative randomized trial

OBJECTIVE

Although joint symptoms are commonly reported after menopause, observational studies examining exogenous estrogen's influence on joint symptoms provide mixed results. Against this background, estrogen-alone effects on joint symptoms were examined in post hoc analyses in the Women's Health Initiative randomized, placebo-controlled, clinical trial.

METHODS

A total of 10,739 postmenopausal women who have had a hysterectomy were randomized to receive daily oral conjugated equine estrogens (0.625 mg/d) or a matching placebo. The frequency and severity of joint pain and joint swelling were assessed by questionnaire in all participants at entry and on year 1, and in a 9.9% random subsample (n = 1,062) after years 3 and 6. Logistic regression models were used to compare the frequency and severity of symptoms by randomization group. Sensitivity analyses evaluated adherence influence on symptoms.

RESULTS

At baseline, joint pain and joint swelling were closely comparable in the randomization groups (about 77% with joint pain and 40% with joint swelling). After 1 year, joint pain frequency was significantly lower in the estrogen-alone group compared with the placebo group (76.3% vs 79.2%, P = 0.001), as was joint pain severity, and the difference in pain between randomization groups persisted through year 3. However, joint swelling frequency was higher in the estrogen-alone group (42.1% vs 39.7%, P = 0.02). Adherence-adjusted analyses strengthen estrogen's association with reduced joint pain but attenuate estrogen's association with increased joint swelling.

CONCLUSIONS

The current findings suggest that estrogen-alone use in postmenopausal women results in a modest but sustained reduction in the frequency of joint pain.

Aromatase inhibitor-induced arthralgia: a review

Though aromatase inhibitors (AIs) are an essential part of estrogen receptor-positive (ER+) breast cancer therapy, many patients discontinue the medicine before their adjuvant therapy is completed because of the arthralgia which often accompanies the medicine. Up to half of women on AI therapy experience joint pain, and up to 20% will become non-compliant with the medicine because of the joint pain. Yet, very little is known about what causes AI-induced arthralgia (AIA), and there is no established, effective treatment for this difficult problem. It compromises survivors' quality of life and leads to non-compliance. This paper will discuss AIA in depth, including potential etiologies, clinical significance, risk factors, and possible management solutions. Of note, this article presents one of the first proposed algorithms which clearly lays out a treatment plan for AIA, incorporating a variety of interventions which have been proven by the available literature.

Epidemiology of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis in the United States and is a leading cause of disability. It is typically defined in epidemiologic studies by radiographic findings and consideration of symptoms. Its incidence and prevalence are rising, likely related to the aging of the population and increasing obesity. Risk factors for OA include numerous person-level factors, such as age, sex, obesity, and genetics, as well as joint-specific factors that are likely reflective of abnormal loading of the joints. In studying OA, several methodologic challenges exist that can hamper our ability to identify pertinent relationships.

Estrogens, osteoarthritis and inflammation

Estrogens participate in several biological processes through different molecular mechanisms. Their final actions consist of a combination of both direct and indirect effects on different organ and tissues. Estrogen may have pro- and anti-inflammatory properties depending on the situation and the involved tissue. In general, acute loss of estrogens increases the levels of reactive oxygen species and activates nuclear factor-κB and pro-inflammatory cytokine production, indicating their predominant anti-inflammatory properties. Furthermore, pro-inflammatory cytokine expression has been shown to be attenuated by estrogen replacement. Osteoarthritis and cardiovascular disease are two of the more prevalent diseases once menopause is established, which has suggested the link between estrogens and both processes. In addition, deletion of estrogen receptors in female mice results in cartilage damage, osteophytosis and changes in the subchondral bone of the joints suggesting that estrogens have a protective role on the maintenance of joint homeostasis. Furthermore, in spite of the negative effect of estrogen replacement reported in 2002 by the Women's Health Initiative study, several works published afterwards have explored the potential protective effect of estrogen supplementation in animal models and have postulated that these actions may justify a beneficial role of estrogens in different diseases where inflammation is the major feature. In this review, we will analyze the effects of estrogens on certain pathological situations such as osteoarthritis, some autoimmune diseases and coronary heart disease, especially in postmenopausal women.

Epidemiology and burden of osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease involving the cartilage and many of its surrounding tissues. Disease progression is usually slow but can ultimately lead to joint failure with pain and disability. OA of the hips and knees tends to cause the greatest burden to the population as pain and stiffness in these large weight-bearing joints often leads to significant disability requiring surgical intervention.

SOURCES OF DATA

The article reviews the existing data on epidemiology of osteoarthritis and the burden of the disease.

AREAS OF AGREEMENT

Symptoms and radiographic changes are poorly correlated in OA. Established risk factors include obesity, local trauma and occupation. The burden of OA is physical, psychological and socioeconomic.

AREAS OF CONTROVERSY

Available data does not allow definite conclusion regarding the roles of nutrition, smoking and sarcopenia as risk factors for developing OA.

GROWING POINTS

Variable methods of diagnosing osteoarthritis have significantly influenced the comparability of the available literature.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research is required to fully understand how OA affects an individual physically and psychologically, and to determine their healthcare need.

Role of sex hormones in the development of osteoarthritis

Women older than 50 years have a considerably higher prevalence of osteoarthritis than men of the same age group. Although several factors have been proposed, there is some evidence that sex hormones influence the development of osteoarthritis. This article will focus on the basic science and clinical evidence that describe the current state of knowledge regarding the relationship between sex hormones and the development of osteoarthritis.

The pathogenesis of osteoarthritis involves bone, cartilage and synovial inflammation: may estrogen be a magic bullet?

The female predominance of polyarticular osteoarthritis (OA), and in particular the marked increase of OA in women after the menopause points to a likely involvement of female sex hormones in the maintenance of cartilage homeostasis. This perception has inspired many research groups to investigate the role of estrogens in the modulation of cartilage homeostasis with the ultimate aim to clarify whether estrogen replacement therapy (ERT) could provide benefits in preventing the rapid rise in the prevalence of OA in postmenopausal women. The effects of ERT and selective estrogen-receptor modulators on the joint in various experimental models have been investigated. Clinically, the effects of estrogens have been evaluated by post hoc analysis in clinical trials using biochemical markers of cartilage and bone degradation. Lastly, the Women's Health Initiative trial (WHI) investigated the effects of estrogens on the joint and joint replacements. Even though the exact mode of action still needs to be elucidated, the effect involves both direct and indirect mechanisms on the whole joint pathophysiology. Several animal models have demonstrated structural benefits of estrogens, as well as significant effects on joint inflammation. This is in complete alignment with clinical data using biochemical markers of joint degradation which demonstrated approximately 50% inhibition of cartilage destruction. These finding were recently validated in WHI, where women taking estrogens had significantly less joint replacement. In conclusion, the pleiotropic effect of estrogens on several different tissues may match the complicated aetiology of OA in some important aspects.

Hippocampal nerve growth factor potentiated by 17β-estradiol and involved in allodynia of inflamed TMJ in rat

The hippocampus is believed to play an important role in sex-based differences of pain perception. Whether estrogen potentiates allodynia in the inflamed temporomandibular joint (TMJ) through affecting the expressions of pain-related genes in the hippocampus remains largely unknown. Because the nerve growth factor (NGF) is an important gene related to inflammatory pain, we tested whether hippocampal NGF may be involved in TMJ inflammatory pain. Here we showed that the rat hippocampal NGF was upregulated by TMJ inflammation induced by complete Freund adjuvant. NGF upregulation was further potentiated by estradiol in a dose-dependent manner. In contrast, NGF transcription in the amygdala, prefrontal cortex, and thalamus was not affected by TMJ inflammation and estradiol. An intrahippocampal injection of NGF antibody or NGF receptor inhibitor K252a (inhibitor for tropomyosin receptor kinase A, TrkA) reduced the allodynia of inflamed TMJ in proestrous rats. Our data suggest that the hippocampal NGF is involved in estradiol-sensitized allodynia of inflammatory TMJ pain.

PERSPECTIVE

We report that complete Freund adjuvant-induced temporomandibular joint (TMJ) inflammation upregulated hippocampal nerve growth factor (NGF) expression, and estradiol replacement potentiated this upregulation. These results propose that estradiol could modulate TMJ pain through the NGF signaling pathway in the hippocampus to exacerbate TMJ pain and offer a possible mechanism of sexual dimorphism of temporomandibular disorder pain.

Targeting bone alleviates osteoarthritis in osteopenic mice and modulates cartilage catabolism

OBJECTIVE

Subchondral bone modifications occur early in the development of osteoarthritis (OA). The level of bone resorption might impact cartilage remodeling. We therefore assessed the in vivo and in vitro effects of targeting bone resorption in OA and cartilage metabolism.

METHODS

OA was induced by meniscectomy (MNX) in ovariectomized osteopenic mice (OP) treated with estradiol (E2), pamidronate (PAM), or phosphate buffered saline (PBS) for 6 weeks. We assessed the subchondral bone and cartilage structure and the expression of cartilage matrix proteases. To assess the involvement of bone soluble factors in cartilage metabolism, supernatant of human bone explants pre-treated with E2 or PAM were transferred to cartilage explants to assess proteoglycan release and aggrecan cleavage. OPG/RANKL mRNA expression was assessed in bone explants by real-time quantitative PCR. The role of osteoprotegerin (OPG) in the bone-cartilage crosstalk was tested using an OPG neutralizing antibody.

RESULTS

Bone mineral density of OP mice and osteoclast number were restored by E2 and PAM (p<0.05). In OP mice, E2 and PAM decreased ADAMTS-4 and -5 expression, while only PAM markedly reduced OA compared to PBS (2.0±0.63 vs 5.2±0.95; p<0.05). OPG/RANKL mRNA was increased in human bone explants treated with both drugs (2.2-3.7-fold). Moreover, supernatants from bone explants cultured with E2 or PAM reduced aggrecan cleavage and cartilage proteoglycan release (73±8.0% and 80±22% of control, respectively, p<0.05). This effect was reversed with osteoprotegerin blockade.

CONCLUSION

The inhibition of bone resorption by pamidronate in osteopenic mice alleviates the histological OA score with a reduction in the expression of aggrecanases. Bone soluble factors, such as osteoprotegerin, impact the cartilage response to catabolic factors. This study further highlights the importance of subchondral bone in the regulation of joint cartilage damage in OA.

Immunohistochemical analysis of the effects of estrogen on intraarticular neurogenic inflammation in a rat anterior cruciate ligament transection model of osteoarthritis

Synovitis is considered as one of the factors associated with the pathogenesis of osteoarthritis (OA). There is currently a significant amount of research linking estrogen deficiencies with the development of OA in estrogen-deficient women, including postmenopausal women; however, the exact etiology remains unclear. Various neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP), have been shown to contribute to synovitis in OA joints, and the influence of estrogen on the expressions of SP and CGRP in the synovium of OA joints has been noted. After ovariectomy (OVX) followed by estradiol (E2) replacement, 24 female rats were divided into three groups: OVX group, OVX + E2 replacement group (E2 group), and a sham group. All rats underwent transection of the anterior cruciate ligament at the same time. After 30 days, the histological findings of knee joints by hematoxylin-eosin staining and immunofluorescence staining of protein gene product 9.5 (pan-neuronal marker), SP, and CGRP were compared among experimental groups. The degree of synovitis in the OVX group was higher than in the E2 and sham groups. No significant differences in the density of protein gene product 9.5-immunoreactive nerve fibers were observed among the three experimental groups, but the density of SP- or CGRP-immunoreactive nerve fibers in the OVX group was significantly higher than in the E2 and sham groups. These findings suggest that estrogen partly regulates intraarticular neurogenic inflammation in OA joints by modulating the expressions of neuropeptides in the synovium.

Risk factors for incident osteoarthritis of the hip and knee

This article reviews the published risk factors associated with incident osteoarthritis of the lower extremity weight-bearing joints. Systemic risk factors include factors such as age, ethnicity, gender and genetic variables. Local risk factors are variables such as obesity, previous knee injury and occupational activities. Challenges in the study of incident osteoarthritis, and promising potential future study directions are also reviewed.

Epidemiology of osteoarthritis

Osteoarthritis (OA) is the most common joint disorder in the United States. Symptomatic knee OA occurs in 10% men and 13% in women aged 60 years or older. The number of people affected with symptomatic OA is likely to increase due to the aging of the population and the obesity epidemic. OA has a multifactorial etiology, and can be considered the product of an interplay between systemic and local factors. Old age, female gender, overweight and obesity, knee injury, repetitive use of joints, bone density, muscle weakness, and joint laxity all play roles in the development of joint OA, particularly in the weight-bearing joints. Modifying these factors may reduce the risk of OA and prevent subsequent pain and disability.

New developments in osteoarthritis. Sex differences in magnetic resonance imaging-based biomarkers and in those of joint metabolism

Sex differences in the prevalence, incidence, and severity of osteoarthritis (OA) have long been known. Some differences in the evaluation of this issue across studies may be related to differences in study design, sampling, study size, study populations, targeted joint sites, and definitions of OA. This report highlights recent studies of sex differences in individual joint components imaged by magnetic resonance imaging and in systemic biomarkers of joint metabolism. Particularly important are those studies that examine this issue in young unaffected adults and children before the development of disease. Despite some variation across studies, women appear for the most part to have a thinner and more reduced volume of cartilage in the knee than men, and this may occur from early childhood. It is not clear whether women have a more accelerated rate of cartilage volume loss than men. Few data exist on sex differences in systemic biomarkers of joint metabolism. In these studies, it is critically important to characterize the total body burden of OA and the presence of comorbid conditions likely to influence a given biomarker. Lastly, future research should dovetail studies of sex differences in imaging and biochemical biomarkers with genetics to maximize insight into the mechanisms behind observed sex differences.

Osteoarthritis in Women: Effects of Estrogen, Obesity and Physical Activity

Arthritis is the leading cause of physical disability in the USA and osteoarthritis (OA), the most common form, affects nearly 27 million people. Women have a higher prevalence of OA than men, but the underlying causes for the increased susceptibility of women to OA are not fully understood. This review discusses the associations of sex hormones, obesity and physical activity with the incidence and progression of OA in women. Although many studies have explored the relationships of estrogen and reproductive history with the risk of OA or joint replacement, there is no consensus on the role of these factors. Obesity clearly increases risk for OA, but whether obesity affects women and men differently is uncertain. Moderate levels of physical activity do not appear to increase the incidence or progression of OA and may even have a weak protective effect. Future investigations should focus on sex-specific mechanisms for the development of OA and determine whether there are modifiable factors (e.g., estrogen, obesity, physical activity) that can be targeted through prevention and treatment strategies to mitigate the increased incidence and prevalence of OA in women.

Common variations in estrogen-related genes are associated with severe large-joint osteoarthritis: a multicenter genetic and functional study

OBJECTIVE

Several lines of evidence suggest that estrogens influence the development of osteoarthritis (OA). The aim of this study was to explore the association of two common polymorphisms within the aromatase (CYP19A1) and estrogen receptor (ER) alpha (ESR1) genes with severe OA of the lower limbs.

METHODS

The rs1062033 (CYP19A1) and rs2234693 (ESR1) single nucleotide polymorphisms were genotyped in 5528 individuals (3147 patients with severe hip or knee OA, and 2381 controls) from four centres in Spain and the United Kingdom. Gene expression was measured in femoral bone samples from a group of patients.

RESULTS

In the global analysis, both polymorphisms were associated with OA, but there was a significant sex interaction. The GG genotype at rs1062033 was associated with an increased risk of knee OA in women [odds ratio (OR) 1.23; P=0.04]. The CC genotype at rs2234693 tended to be associated with reduced OA risk in women (OR 0.76, P=0.028, for knee OA; OR=0.84, P=0.076 for hip OA), but with increased risk of hip OA in men (OR 1.28; P=0.029). Women with unfavourable genotypes at both loci had an OR of 1.61 for knee OA (P=0.006). The rs1062033 genotype associated with higher OA risk was also associated with reduced expression of the aromatase gene in bone.

CONCLUSIONS

Common genetic variations of the aromatase and ER genes are associated with the risk of severe OA of the large joints of the lower limb in a sex-specific manner. These results are consistent with the hypothesis that estrogen activity may influence the development of large-joint OA.

Biochemical markers identify influences on bone and cartilage degradation in osteoarthritis--the effect of sex, Kellgren-Lawrence (KL) score, body mass index (BMI), oral salmon calcitonin (sCT) treatment and diurnal variation

Background

Osteoarthritis (OA) involves changes in both bone and cartilage. These processes might be associated under some circumstances. This study investigated correlations between bone and cartilage degradation in patients with OA as a function of sex, Kellgren-Lawrence (KL) score, Body Mass Index (BMI), oral salmon calcitonin (sCT) treatment and diurnal variation.

Methods

This study was a 2-week, double-blind, double-dummy, randomized study including 37 postmenopausal women and 36 men, aged 57-75 years, with painful knee OA, and a KL-score of I - III. Subjects were allocated to one of three treatment arms: 0.6 mg or 0.8 mg oral sCT, or placebo given twice-daily for 14 days. Correlations between gender, KL score, or BMI and the bone resorption marker, serum C-terminal telopeptide of collagen type I (CTX-I), or the cartilage degradation marker, urine C-terminal telopeptide of collagen type II (CTX-II) were investigated.

Results

At baseline, biomarkers indicated women with OA experienced higher bone and cartilage degradation than men. CTX-I levels were significantly higher, and CTX-II levels only marginally higher, in women than in men (p = 0.04 and p = 0.06, respectively). Increasing KL score was not correlated with bone resorption, but was significantly associated with the cartilage degradation CTX-II marker in both men and women (p = 0.007). BMI was significantly and negatively correlated to the bone resorption marker CTX-I, r = -0.40 (p = 0.002), but showed only a borderline positive correlation to CTX-II, r = 0.25 (p = 0.12). Before morning treatments on days 1 and 14, no correlation was seen between CTX-I and CTX-II in either the sCT or placebo group. However, oral sCT and food intake induced a clear correlation between these bone and cartilage degradation markers. Four hours after the first sCT dose on treatment days 1 and 14, a significant correlation (r = 0.71, p < 0.001) between changes in both CTX-I and CTX-II was seen. In the placebo group a weakly significant correlation between changes in both markers was found on day 1 (r = 0.49, p = 0.02), but not on day 14.

Conclusion

Bone resorption was higher in females than males, while cartilage degradation was correlated with increasing KL-score and only weakly associated with BMI. Bone and cartilage degradation were not correlated in untreated individuals, but dosing with oral sCT with or without food, and a mid-day meal, decreased bone and cartilage degradation and induced a correlation between both markers. Changes in bone and cartilage markers may aid in the identification of potential new treatment opportunities for OA.

Trial Registration

Clinical trial registration number (EUDRACT2006-005532-24 & NCT00486369)

Higher BMC and areal BMD in children and grandchildren of individuals with hip or knee replacement

The relationship between aBMD and osteoarthritis (OA) remains unclear. We compared aBMD, BMC and bone size among children and grandchildren of Hutterites with hip or knee replacement (n=23 each) to children and grandchildren of age- and sex-matched controls (178 children and 267 grandchildren). There were no differences in anthropometric measures or activity levels between case and control probands, but femoral neck (FN) and spine (LS) aBMD and Z-scores were greater in cases than controls (0.89 vs. 0.80 g/cm2; 1.15 vs. 1.03 g/cm2; 1.5 vs. 0.8; 2.4 vs. 1.2: all p<0.05). Hip, FN and LS aBMD (1.05 vs. 0.97, 0.92 vs. 0.84, 1.15 vs. 1.03 g/cm2), BMC (34.1 vs. 32.0, 4.58 vs. 4.27, 69.5 vs. 62.4 g) and Z-scores (1.0 vs. 0.4; 0.9 vs. 0.2; 1.3 vs. 0.2) were greater in daughters of cases than controls (hip BMC p=0.06, others p<0.05); there were no differences between sons. Grandchildren (aged 8-39 years) were categorized as growing (premenarcheal or male<14 years) or not growing (> or =2 years post-menarcheal or males> or =18 years): 33 were not classified. Post-menarcheal, but not premenarcheal, granddaughters of cases had greater hip, FN and LS aBMD Z-scores (0.7 vs. -0.1; 0.6 vs. -0.1; 0.8 vs. -0.3); greater hip and spine aBMD (1.03 vs. 0.95, 1.10 vs. 0.98 g/cm2); greater femoral neck and spine BMC (4.77 vs. 4.21, 66.7 vs. 55.4 g); and greater spine bone area (60.7 vs. 56.6 cm2) compared to granddaughters of controls (all, p<0.05), which remained significant when height, weight, and age were included as covariates. Growing grandsons of cases were taller and heavier than control grandsons, and a greater hip aBMD among grandsons of cases (0.88 vs. 0.76 g/cm2) was the only bone difference that remained significant after taking into account body size differences. Grandsons who were not growing had greater spine bone area (1.19 vs. 1.08 cm2) if their grandparent had OA compared to grandsons whose grandparents did not have OA. We speculate that there is a genetic basis for OA that leads to early differences in growth patterns among boys and greater peak bone mass and aBMD among girls.

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.

Long-Term Prevention with Hormone-Replacement Therapy after the Menopause: Which Women should be Targeted?

For decades, hormone-replacement therapy (HRT) was considered safe and was the first choice in prevention of postmenopausal osteoporosis induced by estrogen deficiency. Numerous experimental and epidemiological studies further supported a protective effect of exogenous female sex hormones on atherogenesis and coronary heart disease (CHD) in women after the menopause. However, the fact that these promising results were not translated into lower incidences of CHD events in hormone-treated women compared with placebo in subsequent, large, randomized studies of healthy subjects as well as women with known CHD raised a very intense debate concerning the safety of HRT in terms of cardiovascular risk. A critical mass of data points toward a protective influence of HRT on cardiovascular disease end points in early postmenopausal women, but increased harm in elderly women, especially those with abdominal adiposity or metabolic syndrome. Once the quasi-hysterical reaction to the largest of the randomized studies (the Women's Health Initiative) has abated, a future strategy should be to concentrate on identifying those relatively few individuals who are not suitable for HRT, as HRT still remains the most thoroughly investigated pharmacological prevention strategy of osteoporosis.

Osteoarthritis associated with estrogen deficiency

Osteoarthritis (OA) affects all articular tissues and finally leads to joint failure. Although articular tissues have long been considered unresponsive to estrogens or their deficiency, there is now increasing evidence that estrogens influence the activity of joint tissues through complex molecular pathways that act at multiple levels. Indeed, we are only just beginning to understand the effects of estrogen deficiency on articular tissues during OA development and progression, as well as on the association between OA and osteoporosis. Estrogen replacement therapy and current selective estrogen receptor modulators have mixed effectiveness in preserving and/or restoring joint tissue in OA. Thus, a better understanding of how estrogen acts on joints and other tissues in OA will aid the development of specific and safe estrogen ligands as novel therapeutic agents targeting the OA joint as a whole organ.

Tibolone inhibits bone resorption without secondary positive effects on cartilage degradation

Background

Osteoarthritis is associated with increased bone resorption and increased cartilage degradation in the subchondral bone and joint. The objective of the present study was to determine whether Tibolone, a synthetic steroid with estrogenic, androgenic, and progestogenic properties, would have similar dual actions on both bone and cartilage turnover, as reported previously with some SERMS and HRT.

Methods

This study was a secondary analysis of ninety-one healthy postmenopausal women aged 52–75 yrs entered a 2-yr double blind, randomized, placebo-controlled study of treatment with either 1.25 mg/day (n = 36), or 2.5 mg/day Tibolone (n = 35), or placebo (n = 20), (J Clin Endocrinol Metab. 1996 Jul;81(7):2419–22) Second void morning urine samples were collected at baseline, and at 3, 6, 12, and 24 months. Urine CrossLaps^® ELISA (CTX-I) and Urine CartiLaps^® ELISA (CTX-II) was investigated as markers of bone resorption and cartilage degradation, respectively.

Results

Tibolone significantly (P < 0.001) suppressed bone resorption by approximately 60%. In contrast, no effect was observed on cartilage degradation.

Conclusion

These data suggest uncoupling of the bone and cartilage effects of the synthetic steroid, Tibolone. Bone resorption was significantly decreased, whereas cartilage degradation was unchanged. These effects are in contrast to those observed some SERMs with effects on both bone and cartilage degradation. These effects may in part be described by the complicated pharmacology of Tibolone on testosterone, estrogen and progesterone receptors.

Epidemiology of osteoarthritis

Evolving definitions of osteoarthritis and improvements in risk factor measurement that use advanced imaging, systemic and local biomarkers, and improved methods for measuring symptoms and their impact can help elucidate mechanisms and identify potential areas for intervention or prevention.

Estrogen and progestogen use in postmenopausal women: July 2008 position statement of The North American Menopause Society

OBJECTIVE

: To update for both clinicians and the lay public the evidence-based position statement published by The North American Menopause Society (NAMS) in March 2007 regarding its recommendations for menopausal hormone therapy (HT) for postmenopausal women, with consideration for the therapeutic benefit-risk ratio at various times through menopause and beyond.

DESIGN

: An Advisory Panel of clinicians and researchers expert in the field of women's health was enlisted to review the March 2007 NAMS position statement, evaluate new evidence through an evidence-based analysis, and reach consensus on recommendations. The Panel's recommendations were reviewed and approved by the NAMS Board of Trustees as an official NAMS position statement. The document was provided to other interested organizations to seek their endorsement.

RESULTS

: Current evidence supports a consensus regarding the role of HT in postmenopausal women, when potential therapeutic benefits and risks around the time of menopause are considered. This paper lists all these areas along with explanatory comments. Conclusions that vary from the 2007 position statement are highlighted. Addenda include a discussion of risk concepts, a new component not included in the 2007 paper, and a recommended list of areas for future HT research. A suggested reading list of key references is also provided.

CONCLUSIONS

: Recent data support the initiation of HT around the time of menopause to treat menopause-related symptoms; to treat or reduce the risk of certain disorders, such as osteoporosis or fractures in select postmenopausal women; or both. The benefit-risk ratio for menopausal HT is favorable close to menopause but decreases with aging and with time since menopause in previously untreated women.

An update review of cellular mechanisms conferring the indirect and direct effects of estrogen on articular cartilage

OBJECTIVE

To review cellular mechanisms that have been proposed to mediate the indirect and direct effects of estrogen on articular cartilage, and to outline the remaining clinical questions that need to be clarified before utilizing the beneficial effects of estrogen for the prevention of osteoarthritis in early postmenopausal women.

DESIGN

Summary of original research papers and reviews listed in Pubmed (1980-2007).

RESULTS

Estrogen receptors have been identified in articular chondrocytes from various animals and humans. Molecular studies showed that estrogen can elicit genomic and rapid non-genomic effects on various cell types, including chondrocytes, and the latter effects are only inducible in females. In addition to direct effects, estrogen can also affect the homeostasis of articular cartilage by modulating the expression/production of different molecules such as various growth factors, inflammatory cytokines, matrix metalloproteinases, and reactive oxygen species. Moreover, in vivo observation argues for the notion that inhibition of subchondral bone turnover is also part of the mechanisms by which estrogen (and antiresorptive agents in general) can protect against joint degradation. Published studies undertaken at cellular, tissue, and in vivo levels illustrate that the effect of estrogen on cartilage may depend on the dose applied, the administration route, the time of initiation, and whether it is combined with a progestin.

CONCLUSIONS

The herein reviewed direct and indirect effects of estrogen on articular cartilage further corroborate the due consideration of estrogen therapy for maintaining not only bone but also cartilage health in postmenopausal women. Future studies in postmenopausal women are needed to clarify whether the efficacy of estrogen therapy can be further optimized by using other forms of estrogen, other progestins, or by initiating the therapy in the peri- or early postmenopausal period.

Modulation of pain by estrogens

It has become increasingly apparent that women suffer a disproportionate amount of pain during their lifetime compared to men. Over the past 15 years, a growing number of studies have suggested a variety of causes for this sex difference, from cellular to psychosocial levels of analysis. From a biological perspective, sexual differentiation of pain appears to occur similarly to sexual differentiation of other phenomena: it results in large part from organizational and activational effects of gonadal steroid hormones. The focus of this review is the activational effects of a single group of ovarian hormones, the estrogens, on pain in humans and animals. The effects of estrogens (estradiol being the most commonly examined) on experimentally induced acute pain vs. clinical pain are summarized. For clinical pain, the review is limited to a few syndromes for which there is considerable evidence for estrogenic involvement: migraine, temporomandibular disorder (TMD) and arthritis. Because estrogens can modulate the function of the nervous, immune, skeletal, and cardiovascular systems, estrogenic modulation of pain is an exceedingly complex, multi-faceted phenomenon, with estrogens producing both pro- and antinociceptive effects that depend on the extent to which each of these systems of the body is involved in a particular type of pain. Forging a more complete understanding of the myriad ways that estrogens can ameliorate vs. facilitate pain will enable us to better prevent and treat pain in both women and men.