Obesity and the female sex, risk factors for knee osteoarthritis that may be attributable to systemic or local leptin biosynthesis and its cellular effects

A systematic review on the effects of non-pharmacological interventions for fatigue among people with upper and/or lower limb osteoarthritis

Objectives

To identify non-pharmacological fatigue interventions and determine the effectiveness of these non-pharmacological interventions in reducing fatigue immediately and over time in OA.

Methods

A review protocol (CRD42020163730) was developed and registered with the PROSPERO database. Included studies comprised peer-reviewed randomized controlled trials (RCTs) that examined the effects of conservative interventions on fatigue in people with upper and lower limb OA. Cochrane Collaboration's tool for assessing the risk of bias (ROB-2) was used to assess the quality of evidence of studies. Narrative synthesis was used to summarize the effectiveness of identified fatigue interventions.

Results

Out of 2644 citations identified from databases, 32 reports were included after screening for titles, abstracts and full texts. Of these reports, 30 parallel RCTs, one cluster and one cross-over RCT were included. 13 RCTs were of low ROB, 6 had some concerns and 13 had high ROB. The narrative synthesis identified interventions for fatigue including exercise, activity pacing, cognitive behavioural therapy, telerehabilitation and complementary alternative therapies. Exercise interventions showed the most significant beneficial effects on fatigue.

Conclusions

Diverse interventions for fatigue management among individuals with upper and lower limb OA were identified. Of these, exercise interventions appear to be the most promising with the majority of these interventions favouring fatigue improvement. While cognitive behavioural therapy has limited evidence of beneficial effects, there is insufficient evidence regarding the effectiveness of other identified interventions, including complementary and alternative therapies, and telerehabilitation.

Sex differences in osteoarthritis prevalence, pain perception, physical function and therapeutics

OBJECTIVE

Women have a higher prevalence of osteoarthritis (OA) and worse clinical courses than men. However, the underlying factors and therapeutic outcomes of these sex-specific differences are incompletely researched. This review examines the current state of knowledge regarding sex differences in OA prevalence, risk factors, pain severity, functional outcomes, and use and response to therapeutics.

METHODS

PubMed database was used with the title keyword combinations "{gender OR sex} AND osteoarthritis" plus additional manual search of the included papers for pertinent references, yielding 212 references. Additional references were added and 343 that were reviewed for appropriateness.

RESULTS

Globally, women account for 60% of people with osteoarthritis with a greater difference after age 40. The higher risk for women may be due to differences in joint anatomy, alignment, muscle strength, hormonal influences, obesity, and/or genetics. At the same radiographic severity, women have greater pain severity than men, which may be explained by biologically distinct pain pathways, differential activation of central pain pathways, differences in pain sensitivity, perception, reporting, and coping strategies. Women have greater limitations of physical function and performance than men independent of BMI, OA severity, injury history, amount of weekly exercise. Women also have greater use of analgesic medications than men but less use of arthroplasty and poorer prognosis after surgical interventions.

CONCLUSIONS

The recognition of sex differences in OA manifestations and management could guide tailoring of sex-specific treatment protocols, and analysis of sex as a biological variable in future research would enhance development of precision medicine.

Sex-specific effects of calving season on joint health and biomarkers in Montana ranchers

BACKGROUND

Agricultural workers have a higher incidence of osteoarthritis (OA), but the etiology behind this phenomenon is unclear. Calving season, which occurs in mid- to late-winter for ranchers, includes physical conditions that may elevate OA risk. Our primary aim was to determine whether OA biomarkers are elevated at the peak of calving season compared to pre-season, and to compare these data with joint health survey information from the subjects. Our secondary aim was to detect biomarker differences between male and female ranchers.

METHODS

During collection periods before and during calving season, male (n = 28) and female (n = 10) ranchers completed joint health surveys and provided samples of blood, urine, and saliva for biomarker analysis. Statistical analyses examined associations between mean biomarker levels and survey predictors. Ensemble cluster analysis identified groups having unique biomarker profiles.

RESULTS

The number of calvings performed by each rancher positively correlated with plasma IL-6, serum hyaluronic acid (HA) and urinary CTX-I. Thiobarbituric acid reactive substances (TBARS), a marker of oxidative stress, was significantly higher during calving season than pre-season and was also correlated with ranchers having more months per year of joint pain. We found evidence of sexual dimorphism in the biomarkers among the ranchers, with leptin being elevated and matrix metalloproteinase-3 diminished in female ranchers. The opposite was detected in males. WOMAC score was positively associated with multiple biomarkers: IL-6, IL-2, HA, leptin, C2C, asymmetric dimethylarginine, and CTX-I. These biomarkers represent enzymatic degradation, inflammation, products of joint destruction, and OA severity.

CONCLUSIONS

The positive association between number of calvings performed by each rancher (workload) and both inflammatory and joint tissue catabolism biomarkers establishes that calving season is a risk factor for OA in Montana ranchers. Consistent with the literature, we found important sex differences in OA biomarkers, with female ranchers showing elevated leptin, whereas males showed elevated MMP-3.

Osteoarthritis in early modern population from Dąbrówki (Podlaskie Province)

The aim of this analized is to evaluate the frequency of osteoarthritis in the early modern population of Dąbrówki (Poland). Evaluation of degenerative joint changes was based on standard methods commonly used in physical anthropology. Three types of changes were studied: osteophytes, porosities, and eburnations. They were analyzed in the shoulder, elbow, wrist, hip, knee, and proximal ankle joints. Osteoarthritic changes were assessed in 24 female, 20 male, and 8 undetermined sex individuals in the Dąbrówki population. In the population from Dąbrówki the highest frequency of degenerative changes was noted in the hip joint, and the lowest in the knee joint. Osteophytes were the predominant type of lesions. The less frequent type was porosity, while polishing of the articular surfaces did not occur. In males, degenerative changes were noted more frequently than in females. Due to the existence of many interpretative limitations (there is no a complete picture of the population from Dąbrówki - skeletal material under exploration; not entirely clear and multifactorial etiology of degenerative joint changes), further analysis of the markers of environmental stress in the population from Dąbrówki is necessary.

Effects of Greenshell Mussel (Perna canaliculus) Intake on Pathological Markers of Multiple Phenotypes of Osteoarthritis in Rats

The prevalence of metabolic osteoarthritis has been increasing worldwide, particularly among women. The aim of this study was to investigate the effects of the New Zealand greenshell mussel (Perna canaliculus; GSM) on osteoarthritis (OA) prevention in a rat model. One-hundred-and-eight female rats aged 12 weeks were divided into four test groups, containing 24 rats each, plus an additional control group. Each test group received one of the four experimental diets: normal control diet (ND), normal control diet supplemented with GSM (ND + GSM), high fat/high sugar diet (HFHS), or high fat/high sugar diet supplemented GSM (HFHS + GSM), for 36 weeks (end of the study). After 8 weeks on experimental diets, half of each group was subjected to ovariectomy (OVX) and the remaining half received a sham operation (ovaries left intact). The study evaluated body composition, bone mass, plasma cytokines, adipokines, HbA1c, CTX-II, and knee joint’s histopathology. HFHS diet and OVX significantly induced body weight gain and leptin production. OVX rats lost bone mineral density but increased adiponectin, HbA1C, and MCP-1. The OVX rats fed HFHS showed the highest Mankin scores. Importantly, inclusion of GSM reduced these pathological features. In conclusion, GSM might be beneficial in halting the progression of OA.

Role of Leptin in Inflammation and Vice Versa

Inflammation is an essential immune response for the maintenance of tissue homeostasis. In a general sense, acute and chronic inflammation are different types of adaptive response that are called into action when other homeostatic mechanisms are insufficient. Although considerable progress has been made in understanding the cellular and molecular events that are involved in the acute inflammatory response to infection and tissue injury, the causes and mechanisms of systemic chronic inflammation are much less known. The pathogenic capacity of this type of inflammation is puzzling and represents a common link of the multifactorial diseases, such as cardiovascular diseases and type 2 diabetes. In recent years, interest has been raised by the discovery of novel mediators of inflammation, such as microRNAs and adipokines, with different effects on target tissues. In the present review, we discuss the data emerged from research of leptin in obesity as an inflammatory mediator sustaining multifactorial diseases and how this knowledge could be instrumental in the design of leptin-based manipulation strategies to help restoration of abnormal immune responses. On the other direction, chronic inflammation, either from autoimmune or infectious diseases, or impaired microbiota (dysbiosis) may impair the leptin response inducing resistance to the weight control, and therefore it may be a cause of obesity. Thus, we are reviewing the published data regarding the role of leptin in inflammation, and the other way around, the role of inflammation on the development of leptin resistance and obesity.

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.

Relationships between osteoarthritic changes (osteophytes, porosity, eburnation) based on historical skeletal material

Background: Three main diagnostic types of osteoarthritic changes are distinguished in clinical and anthropological literature: osteophytes, porosity, and eburnation. The nature of the relationship between these changes and how lesions progress over time is still unclear.Aim: The aim of the present study is the analysis of the relationships between osteophytes, porosity, and eburnation based on skeletal material.Subjects and methods: The analysis employed the skeletal collection from Cedynia (199 individuals) from tenth to fourteenth-century Poland. Marginal osteophytes (OP), porosity (POR), and eburnation (EB) were examined on a shoulder, elbow, wrist, hip, knee, and ankle.Results: Osteophytes and porosity occurred independently of each other. Combinations of osteophytes and porosity (OP + POR) and osteophytes, porosity, and eburnation (OP + POR + EB) were rarely observed. Combinations of osteophytes and eburnation (OP + EB) or porosity and eburnation (POR + EB) were not found. There was a significant correlation between osteophytes and porosity in the scapula, proximal end of the ulna and proximal end of the femur. Osteophytes and eburnation were correlated at the distal end of the ulna. Porosity and eburnation were correlated at the distal end of the radius and distal end of the ulna. When all joints were considered together, all the types of osteoarthritic changes were correlated. However, the relationship between osteophytes and eburnation and between porosity and eburnation was only slightly significant. Osteophytes preceded porosity, but there were a few cases where more developed porosity accompanied less developed osteophytes.Conclusions: The findings indicate that correlations between osteoarthritic changes are weak, albeit statistically significant and further studies of the relationship between changes are necessary.

Leptin levels are associated with multiple sclerosis risk

BACKGROUND

Obesity early in life has been linked to increased risk of developing multiple sclerosis (MS). Leptin and insulin are both associated with obesity, making them suitable candidates for investigating this connection.

OBJECTIVE

To determine if leptin and insulin are risk factors for relapsing-remitting multiple sclerosis (RRMS).

METHODS

In this nested case-control study using blood samples from Swedish biobanks, we compared concentrations of leptin and insulin in 649 individuals who later developed RRMS with 649 controls matched for biobank, sex, age and date of sampling. Only pre-symptomatically drawn samples from individuals below the age of 40 years were included. Conditional logistic regression was performed on z-scored values to calculate odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A 1-unit leptin z-score increase was associated with increased risk of MS in individuals younger than 20 years (OR = 1.4, 95% CI = 1.1-1.9) and in all men (OR = 1.4, 95% CI = 1.0-2.0). In contrast, for women aged 30-39 years, there was a lower risk of MS with increased leptin levels (OR = 0.74, 95% CI = 0.54-1.0) when adjusting for insulin levels.

CONCLUSION

We show that the pro-inflammatory adipokine leptin is a risk factor for MS among young individuals.

Interaction of Osteoarthritis and BMI on Leptin Promoter Methylation in Taiwanese Adults

Leptin (LEP) regulates glucose metabolism and energy storage in the body. Osteoarthritis (OA) is associated with the upregulation of serum LEP. LEP promoter methylation is associated with obesity. So far, few studies have explored the association of BMI and OA with LEP methylation. We assessed the interaction between body mass index (BMI) and OA on LEP promoter methylation. Data of 1114 participants comprising 583 men and 558 women, aged 30–70 years were retrieved from the Taiwan Biobank Database (2008–2015). Osteoarthritis was self-reported and cases were those who reported having ever been clinically diagnosed with osteoarthritis. BMI was categorized into underweight, normal weight, overweight, and obesity. The mean LEP promoter methylation level in individuals with osteoarthritis was 0.5509 ± 0.00437 and 0.5375 ± 0.00101 in those without osteoarthritis. The interaction between osteoarthritis and BMI on LEP promoter methylation was significant (p-value = 0.0180). With normal BMI as the reference, the mean LEP promoter methylation level was significantly higher in obese osteoarthritic individuals (β = 0.03696, p-value = 0.0187). However, there was no significant association between BMI and LEP promoter methylation in individuals without osteoarthritis, regardless of BMI. In conclusion, only obesity was significantly associated with LEP promoter methylation (higher levels) specifically in osteoarthritic patients.

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.

Association of preoperative pain in knee and external to knee with postoperative pain outcome after total knee arthroplasty

Background

Preoperative pain in the symptomatic knee may predict postoperative pain severity in patients undergoing total knee arthroplasty (TKA). However, the effect of preoperative pain external to the knee on postoperative pain is unclear. This study evaluated postoperative pain outcomes in TKA patients according to the presence of preoperative pain in the knee only or in the knee and external to the knee.

Methods

We retrospectively assessed medical records of patients who underwent unilateral TKA. The relationship between reported preoperative pain characteristics and morphine equivalent consumption or numerical rating scale (NRS) pain scores on postoperative day (POD) 0-3 was assessed using a multivariable generalized linear model.

Results

In total, 3,429 adult patients who underwent their first TKA were included; 2,864 (83.5%) patients preoperatively experienced only knee pain and 565 (16.5%) knee pain with external to knee pain. Preoperative pain in the knee and external to the knee was associated with 5% higher morphine equivalent consumption on POD 0-3 compared to preoperative knee pain only (exponentiated regression coefficient: 1.05; 95% confidence interval: 1.02 to 1.09; P = 0.004). However, the NRS pain scores on POD 0, 1, 2, and 3 and adjuvant analgesics consumption (acetaminophen and ketorolac) on POD 0-3 were not significantly different between the two groups (P > 0.05).

Conclusions

This study showed that there was an increase of morphine equivalent consumption during POD 0-3 in patients with preoperative knee pain with external to knee pain than in patients with preoperative only knee pain.

The Preventive Effects of Greenshell Mussel (Perna canaliculus) on Early-Stage Metabolic Osteoarthritis in Rats with Diet-Induced Obesity

The prevalence of osteoarthritis (OA) is rising worldwide, with the most pronounced increase being in the category of metabolic-associated osteoarthritis (MetOA). This is predicted to worsen with the global rise in aging societies and obesity. To address this health burden, research is being conducted to identify foods that can reduce the incidence or severity of MetOA. Oil from the Greenshell mussel (Perna canaliculus) (GSM), a native New Zealand shellfish, has been successfully used to reduce OA symptoms. The current study assessed the effect of including flash-dried powder from whole GSM meat as part of a normal (control) versus high-fat/high-sugar (HFHS) diet for 13 weeks on the development of MetOA in rats. Rats fed a HFHS diet developed metabolic dysregulation and obesity with elevated plasma leptin and HbA1C concentrations. Visible damage to knee joint cartilage was minimal, but plasma levels of C telopeptide of type II collagen (CTX-II), a biomarker of cartilage degradation, were markedly higher in HFHS-fed rats compared to control-fed rats. However, rats fed the HFHS diet containing GSM had significantly reduced serum CTX-II. Inclusion of GSM in rats fed the control diet also lowered CTX-II. These findings suggest that dietary GSM can reduce the incidence or slow the progression of early MetOA.

Risk factors of knee osteoarthritis: A case-control study

Background and Objective

Knee osteoarthritis is one of the most common rheumatologic problems. To investigate risk factors related to the knee osteoarthritis a case-control study was performed using cases diagnosed in the Community Oriented Program for Control of Rheumatic Diseases (COPCORD) study, stage I.

Methods

Using data from the 2012 COPCORD study, stage-I that was conducted in Sanandaj, northwestern of Iran, we runned a case-control study in 2014-2015. Cases were 700 knee osteoarthritis using American College of Rheumatology (ACR) criteria, frequency matched with 700 healthy controls that were randomly selected from the general population.

Results

In multivariate analysis, statistical significant relation was observed between knee OA and some studied factors such as body mass index (P <0.001), lodging (living in highland vs. plain) (P <0.001), type of used toilet (regular vs. toilet) (P <0.001), history of using high-heeled shoes (>3 cm) (P = 0.005), history of knee Injury (P = 0.04), history of lower limb fracture (P = 0.02), Number of pregnancies (P <0.001) and history of pain and swelling (lasting for one months) (P = 0.04).

Conclusions

Living in highland area, using regular toilet, having knee injury and lower limb fracture in the past were most significant associated factors with occurrence of knee osteoarthritis.

Severity and distribution of cartilage damage and bone marrow edema in the patellofemoral and tibiofemoral joints in knee osteoarthritis determined by MRI

The aim of the present study was to analyze the distribution and severity of cartilage damage (CD) and bone marrow edema (BME) of the patellofemoral and tibiofemoral joints (PFJ and TFJ, respectively) in patients with knee osteoarthritis (OA), and to determine whether a correlation exists between BME and CD in knee OA, using magnetic resonance imaging (MRI). Forty-five patients diagnosed with knee OA (KOA group) and 20 healthy individuals (control group) underwent sagittal multi-echo recalled gradient echo sequence scans, in addition to four conventional MR sequence scans. Knee joints were divided into 15 subregions by the whole-organ MRI scoring method. MRIs of each subregion were analyzed for the presence of CD, CD score and BME score. The knee joint activity functional score was determined using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) in the KOA group. Statistical analyses were used to compare the CD incidence; CD score and BME score between the PFJ and TFJ. Whether a correlation existed among body mass index, BME score, WOMAC pain score and CD score was also examined. Among the 675 subregions analyzed in the KOA group, 131 exhibited CD (CD score, 1-6). These 131 subregions were primarily in the PFJ (80/131, 61.07%), with the remainder in the TFJ (51/131, 38.93%). Thirty-three subregions had a CD score of 1, including 24 PFJ subregions (72.73%) and 9 TFJ subregions (27.27%). Among the 103 subregions with BME, the PFJ accounted for 60 (58.25%) and the TFJ for 43 (41.75%). A significant positive correlation was found between the BME and CD scores. In conclusion, CD and BME occurred earlier and more often in the PFJ compared to the TFJ in knee OA, and BME is an indirect sign of CD.

Role of leptin as a link between metabolism and the immune system

Leptin is an adipocyte-derived hormone not only with an important role in the central control of energy metabolism, but also with many pleiotropic effects in different physiological systems. One of these peripheral functions of leptin is a regulatory role in the interplay between energy metabolism and the immune system, being a cornerstone of the new field of immunometabolism. Leptin receptor is expressed throughout the immune system and the regulatory effects of leptin include cells from both the innate and adaptive immune system. Leptin is one of the adipokines responsible for the inflammatory state found in obesity that predisposes not only to type 2 diabetes, metabolic syndrome and cardiovascular disease, but also to autoimmune and allergic diseases. Leptin is an important mediator of the immunosuppressive state in undernutrition status. Placenta is the second source of leptin and it may play a role in the immunomodulation during pregnancy. Finally, recent work has pointed to the participation of leptin and leptin receptor in the pathophysiology of inflammation in oral biology. Therefore, leptin and leptin receptor should be considered for investigation as a marker of inflammation and immune activation in the frontier of innate-adaptive system, and as possible targets for intervention in the immunometabolic mediated pathophysiology.

Prevention of Incident Knee Osteoarthritis by Moderate Weight Loss in Overweight and Obese Females

OBJECTIVE

This study evaluated the effect of moderate weight loss on the incidence of knee osteoarthritis (OA) in middle-aged overweight and obese women, without clinical and radiologic knee OA at baseline.

METHODS

A total of 353 women (87%) with followup data available were selected from the Prevention of Knee Osteoarthritis in Overweight Females study, which evaluated the preventive effect of a diet and exercise intervention and of oral glucosamine sulfate on the incidence of knee OA. This was an exploratory proof-of-concept analysis, which compared the incidence of knee OA between women who reached the clinically relevant weight loss target of 5 kg or 5% of body weight after 30 months and those who did not reach this target.

RESULTS

The weight loss group showed a significantly lower incidence of knee OA according to the primary outcome measure, which was composed of the American College of Rheumatology criteria (clinical and radiographic), Kellgren/Lawrence grade ≥2, and joint space narrowing ≥1.0 mm (15% versus 20%; odds ratio 0.5, 95% confidence interval 0.3-0.9). Moreover, the weight loss also positively affected several health measures, such as blood glucose level, body fat percentage, and blood pressure.

CONCLUSION

A reduction of ≥5 kg or 5% of body weight over a 30-month period reduces the risk for the onset of radiographic knee OA in middle-aged overweight and obese women. Because of the slow progression of the disease, a longer followup period will be necessary before the number of prevented cases of knee OA by moderate weight loss becomes clinically more relevant.

An update on the pathophysiology of osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is one of the most common forms of arthritis. There is accumulating evidence to suggest that OA is an inflammatory disease of the entire synovial joint and has multiple phenotypes. This presents the OA research community with new challenges and opportunities. The main challenge is to understand the root cause of the disease and identify differences and similarities between OA phenotypes. The key opportunity is the possibility of developing personalized and individualized prevention and treatment strategies for OA patients with different phenotypes of the disease. Indeed, it has been suggested that this is the era of 'personalized prevention' for OA. The aim of this mini-review paper is to focus on the pathophysiological aspects of OA development and progression, review the current concepts and discuss the future of personalized medicine for OA.

METHOD

The PubMed/MEDLINE bibliographic database was searched using the keywords 'pathophysiology' and 'osteoarthritis'.

RESULTS

The PubMed/MEDLINE search yielded more than 12,000 relevant papers. A selection of these papers is reviewed here.

CONCLUSION

There has been slow but steady progress in our understanding of the pathophysiology of OA over the last two decades. However, large gaps remain in our knowledge of OA pathogenesis and this impacts negatively on patients and drug development pipeline. In the absence of new pharmaceutical agents and disease modifying osteoarthritis drugs (DMOADs) it is clear that lifestyle modification and physical activity are important and may delay the need for surgical intervention.

Association of rs1137101 polymorphism in LEPR and susceptibility to knee osteoarthritis in a Northwest Chinese Han population

Background

Osteoarthritis (OA) is a complex arthritic condition in which the genetic factor plays a crucial role. A single nucleotide polymorphism (SNP), rs1137101 (Gln223Arg) of leptin receptor (LEPR) gene has been demonstrated to be associated with susceptibility to knee OA. However, this association in Chinese Han population has never been examined. The present study aimed to investigate whether Gln223Arg was related to knee OA susceptibility in a Northwest Chinese population with Han ethnicity.

Methods

Gln223Arg polymorphisms were genotyped in 587 patients with confirmed knee OA and in 628 age- and sex-matched healthy controls using polymerase chain reaction-restriction fragment length polymorphism analysis. Besides, LEPR genotypes were verified by direct DNA sequencing analysis on PCR products.

Results

The genotype and allele frequencies in LEPR SNP rs1137101 were significantly different between cases and control groups (chi-square = 6.52, P = 0.038 for genotype and chi-square = 5.06, P = 0.024 for allele frequencies; respectively). Rs1137101 was correlated with knee OA in the dominant genetic model (GG + GA versus AA) (P = 0.016) and a higher G allele frequency existed (P = 0.024) among all patients with knee OA and controls. On stratification analysis, the genotype GG and G allele were associated with susceptibility to knee OA in females, both young (≤65 years) and old groups (>65 years) and patients with mild knee OA.

Conclusions

Our finding suggested that the genetic variant of LEPR gene rs1137101 is independently related to knee OA susceptibility in Northwest Chinese population with Han ethnicity and may serve as a potential biomarker to determine risk of knee OA.

Influence of body mass index in revision total knee arthroplasty

OBJECTIVE

: To evaluate the influence of the body mass index (BMI) on the functional assessment of patients who underwent revision total knee arthroplasty (RTKA).

METHODS

: Thirty patients who un-derwent RTKA between January 2008 and January 2012 were retrospectively assessed using the WOMAC questionnaire. The patients were divided into three groups according to the BMI ca-tegories defined by the World Health Organization (WHO): Group I with normal BMI (18-24.9 Kg/m²⁾, with eight patients; Group II, overweight (BMI 25-29.9 Kg/m²⁾, with 15 patients, and Group III obesity with BMI ≥ 30 Kg/m², with seven patients. The post-ope-rative function scores obtained through the WOMAC questionnaire were compared with the BMI of each group. The statistical analysis between BMI and WOMAC scores was performed with the Spe-arman correlation test.

RESULTS

: The average functional WOMAC score for individuals in Group I was 16.7; in Group II it was 47.7; and in Group III it was 69.9, with a statistically significant differen-ce between groups I, II and III (p< 0.0001).

CONCLUSION

: Patients with BMI > 25 Kg/m² had a worse functional evaluation through WOMAC scores when compared to patients with normal BMI after RTKA. Level of Evidence III, Tranversal Retrospective Study.

Associations between socioeconomic status and primary total knee joint replacements performed for osteoarthritis across Australia 2003-10: data from the Australian Orthopaedic Association National Joint Replacement Registry

Background

Relatively little is known about the social distribution of total knee joint replacement (TKR) uptake in Australia. We examine associations between socioeconomic status (SES) and TKR performed for diagnosed osteoarthritis 2003–10 for all Australian males and females aged ≥30 yr.

Methods

Data of primary TKR (n = 213,018, 57.4% female) were ascertained from a comprehensive national joint replacement registry. Residential addresses were matched to Australian Census data to identify area-level social disadvantage, and categorised into deciles. Estimated TKR rates were calculated. Poisson regression was used to model the relative risk (RR) of age-adjusted TKR per 1,000py, stratified by sex and SES.

Results

A negative relationship was observed between TKR rates and SES deciles. Females had a greater rate of TKR than males. Surgery utilisation was greatest for all adults aged 70-79 yr. In that age group differences in estimated TKR per 1,000py between deciles were greater for 2010 than 2003 (females: 2010 RR 4.32 and 2003 RR 3.67; males: 2010 RR 2.04 and 2003 RR 1.78).

Conclusions

Identifying factors associated with TKR utilisation and SES may enhance resource planning and promote surgery utilisation for end-stage osteoarthritis.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-356) contains supplementary material, which is available to authorized users.

Body fat predicts an increase and limb muscle strength predicts a decrease in leptin in older adults over 2·6 years

OBJECTIVE

Obesity is characterized by hyperleptinaemia, which is associated with diabetes, hypertension and coronary heart disease. The aim of this study was to determine if body fat and muscle measures predict the natural increase in leptin over 2·6 years in older adults.

METHODS

A total of 190 subjects (50% females) aged between 50 and 79 years were selected to perform the serum measurements for leptin. Height and weight were measured and body mass index (BMI) was calculated. Fat and lean mass of the whole body and the trunk were acquired through dual-energy X-ray absorptiometry (DXA). Leg muscle strength and handgrip strength were measured using dynamometry.

RESULTS

In multivariable analyses, leg muscle strength was negatively associated with both baseline leptin (β: -0·05 μg/l per kg, 95% CI: -0·08, -0·02) and follow-up leptin (β: -0·04 μg/l per kg, 95% CI: -0·07, -0·01). BMI, and percentage total fat and trunk fat and their respective change per annum (cpa) were significantly and positively associated with leptin. Lean mass was negatively associated with baseline leptin. Gender-specific analyses produced similar associations between leg muscle strength, fat measures and follow-up leptin in males and females.

CONCLUSION

Besides positive associations between body fat, trunk fat and leptin, we found that leg muscle strength was negatively associated with leptin after 2·6 years in a sample of older population. This suggests that interventions to maintain or increase muscle strength may have a protective effect on hyperleptinaemia.

Cross-sectional and longitudinal associations between circulating leptin and knee cartilage thickness in older adults

Objective

To investigate cross-sectional and longitudinal associations between serum leptin levels and knee cartilage thickness in older adults.

Methods

A prospective cohort of 163 randomly selected subjects (mean 63 years, range 52–78, 46% women) was studied. Knee cartilage thickness at medial tibial, lateral tibial, femoral and patellar sites was determined using T1-weighted fat-suppressed MRI. Serum leptin levels were measured by radioimmunoassay. Radiographic osteoarthritis, body fat (%), trunk fat (%), weight and height were measured, and body mass index (BMI) was calculated.

Results

Cross-sectionally, serum levels of leptin were negatively associated with femoral (β: −0.013, 95% CI −0.022 to −0.003), medial tibial (β: −0.009, 95% CI −0.018 to −0.001), lateral tibial (β: −0.012, 95% CI −0.021 to −0.003) and patellar (β: −0.014, 95% CI −0.026 to −0.002) cartilage thickness after adjustment for covariates. Moreover, BMI, trunk fat and total body fat were negatively associated with cartilage thickness, and the significant associations disappeared after further adjustment for leptin. Longitudinally, both baseline leptin and change in leptin were associated with greater changes in medial tibial cartilage thickness (β: −0.004, 95% CI −0.007 to −0.001 and β: −0.009, 95% CI −0.018 to −0.001, respectively) in multivariable analyses.

Conclusions

Serum levels of leptin are independently and consistently associated with reduced cartilage thickness cross-sectionally and longitudinally. In addition, the associations between adiposity measures and cartilage thickness are mediated by leptin, suggesting leptin may play a key role in cartilage thinning.

The association of adipokine levels in plasma and synovial fluid with the severity of knee osteoarthritis

OBJECTIVE

We sought to determine the association between plasma and SF levels of leptin and adiponectin in patients with knee OA.

METHODS

Plasma and SF levels of adipokines and soluble leptin receptor (sOB-R) were determined by ELISA in 96 patients with knee OA at different stages, according to Ahlback's classification.

RESULTS

Levels of adiponectin, leptin, sOB-R and free leptin in plasma and SF did not differ significantly across categories of OA severity. However, the ratio of SF to plasma leptin was significantly lower in the advanced OA stage compared with early stages of the disease (P = 0.02). After adjustment for sex and BMI, plasma leptin positively correlated with categories of OA severity (r = 0.23, P = 0.02), whereas SF/plasma leptin negatively correlated with OA stage (r = -0.27, P = 0.01). Cluster analysis showed that all men were included in one cluster and distributed in different stages of OA, whereas women formed three clusters with similar BMI, but those who were older and had the highest plasma leptin levels suffered from advanced OA.

CONCLUSION

Plasma leptin positively correlated with the severity of knee OA. The ratio of SF to plasma leptin might be a marker related to the severity of knee OA. Further studies should investigate whether similar associations exist in other joints affected by OA.

A randomized comparative study of safety and efficacy of immediate release glucosamine HCL and glucosamine HCL sustained release formulation in the treatment of knee osteoarthritis: A proof of concept study

Objectives:

To compare the safety and efficacy of glucosamine HCl- sustained release (GLU-SR) with that of Glucosamine HCl- immediate release (GLU-IR) in patients with knee osteoarthritis (OA).

Materials and Methods:

This study involved 59 patients with knee OA, randomised to receive single oral dose of 1,500 mg, GLU-SR and GLU-IR for 60 days with 31 and 28 patients, respectively. The primary efficacy (pain and function) was assessed using visual analogue scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. Intention-to-treat principle, repeated measure of ANOVA and mixed model analysis were used.

Results:

The patients baseline, demographic and clinical characteristics were comparable between groups with female preponderance (71.20%). There was a significant reduction in algofunctional indices as primary outcome measure in both the groups across time (P < 0.001) and 29% lesser adverse events (AEs) in GLU-SR group, with no difference in the use of rescue medications.

Conclusions:

The study showed equal efficacy of the glucosamine formulations on algofunctional indices in reducing pain in patients with knee OA with less number of AEs in GLU-SR.

Adiponectin interactions in bone and cartilage biology and disease

The adipokine adiponectin promotes insulin sensitivity and fat β-oxidation. In addition to its metabolic effects, adiponectin is an important local and systemic modulator of bone remodeling and cartilage biology, involving direct and indirect mechanisms and a large set of downstream molecular signals. Moreover, data suggest that changes in adiponectin signaling may be associated with bone and cartilage diseases. Adiponectin seems to exert a negative net effect on bone mass and to be an independent predictor of lower bone mass, whereas available data about actions on cartilage are more controversial, showing both pro- and anti-inflammatory actions. Adiponectin-bone cross talk seems to be reciprocal, as osteocalcin, produced by osteoblasts, has been shown to stimulate adiponectin expression and to improve glucose tolerance. Adiponectin-related signaling in bone and cartilage should be considered within the network of hormonal and nutritional signals that may influence skeleton biology, together with body homeostasis and adipose mass changes.

Adipokine actions on cartilage homeostasis

Epidemiological studies have shown an intriguing correlation between obesity and articular cartilage disease. An increase in mechanical forces across weight-bearing joints has long been considered the primary factor leading to joint degeneration. However, emerging data suggest that additional soluble factors such as the adipocyte-derived molecules "adipokines" may also play an important role in the onset and progression of weight-associated cartilage degradative process. Adipokines are pleiotropic secretory molecules mainly produced by white adipose tissue. Adipokines exert their actions through endocrine, paracrine, autocrine, or juxtacrine cross talk in a wide variety of physiological or pathophysiological processes. In particular, they are mainly involved in the regulation of food intake and energy metabolism, in both health and disease states, and in the inflammatory response. Recent observations have shown that, among adipokines, leptin, adiponectin, resistin, visfatin, and apelin may also participate to the complex mechanisms that regulate skeleton biology, both at bone and cartilage level. Herein, we review the present knowledge about the role of these adipokines in cartilage function as well as in inflammatory and degenerative joint diseases. Moreover, we describe some methodological approaches which can be utilized in the measurement of these adipokines in different biological matrices, like plasma and synovial fluid (SF), and may be helpful to better clarify the involvement of these molecules in cartilage disease.

Influence of signalment on developing cranial cruciate rupture in dogs in the UK

OBJECTIVES

To investigate risk factors associated with cranial cruciate ligament rupture in dogs.

METHODS

Retrospective case-control study: medical records of a first-opinion veterinary practice were searched for dogs diagnosed with cranial cruciate ligament rupture (1995 to 2007). For each case, six unaffected dogs were randomly selected from all dogs presenting that day for comparison. Multi-variable binary logistic regression was performed to assess the association of variables on likelihood of cruciate rupture.

RESULTS

Frequency of cranial cruciate ligament rupture was 1·19% [95% confidence interval (CI) 1·02 to 1.36%]. West Highland white terriers (n=17), Yorkshire terriers (n=14) and Rottweilers (n=11) were at significantly increased risk of cranial cruciate ligament rupture (P≤0·002). Rottweilers were at five times greater risk compared with other pure breeds (OR 5·12, 95% CI 2·281 to 11·494, P<0·001), obesity quadrupled the risk of cranial cruciate ligament rupture (OR 3·756, 95% CI 1·659 to 8·502, P=0·001) and females were twice as likely to suffer cranial cruciate ligament failure compared to males (OR 2·054, 95% CI 1·467 to 2·877, P<0·001). Dogs less than two years old were statistically less likely to sustain cranial cruciate ligament rupture than dogs older than eight years (OR 0·246, 95% CI 0·127 to 0·477, P<0·001). There was no significant difference in median weights (in kilograms) of neutered dogs, compared to their entire counterparts in either the case group (P=0·994) or in the control group (P=0·630). There was also no significant difference in body condition (-underweight/normal weight/overweight/obese) of neutered versus entire dogs among the cases (P=0·243), or the controls (P=0·211).

CLINICAL SIGNIFICANCE

Cranial cruciate ligament rupture is more likely in Rottweilers and in female dogs, older dogs and obese dogs. Following multi-variable analysis, it was established that neutering was not associated with increased risk of cranial cruciate ligament rupture.

Serum leptin concentration positively correlates with body weight and total fat mass in postmenopausal Japanese women with osteoarthritis of the knee

The objective of the present study was to identify factors correlated with the serum leptin concentration in women with knee OA. Fifty postmenopausal Japanese women with knee OA (age: 50-88 years) were recruited in our outpatient clinic. Plain radiographs of the knee were taken, and urine and blood samples were collected. Dual-energy X-ray absorptiometry (DXA) scanning was performed for the whole body and lumbar spine, and factors correlated with the serum leptin concentration were identified. A simple linear regression analysis showed that body weight, body mass index, whole-body bone mineral density (BMD), total fat mass, and total fat percentage, but not age, height, lumbar spine BMD, lean body mass, serum and urinary bone turnover markers, or the radiographic grade of knee OA, were significantly correlated with the serum leptin concentration. A multiple regression analysis showed that among these factors, only body weight and total fat mass exhibited a significant positive correlation with the serum leptin concentration. These results suggest that the serum leptin concentration might be related to increases in body weight and total fat mass, but not to BMD or bone turnover markers, in postmenopausal women with OA.

Age-associated increases in the size of the infrapatellar fat pad in knee osteoarthritis as measured by 3T MRI

Obesity, as a primary risk factor for osteoarthritis (OA), has been shown to alter joint loading, but may also result in metabolic changes characterized by chronic, low-level inflammation due to increased circulating levels of adipose-derived cytokines, or "adipokines." The presence of the infrapatellar fat pad in the knee suggests that local changes in adipokine concentrations may influence knee OA. This study examined the hypotheses that the volume of the infrapatellar fat pad is correlated to the body mass index (BMI) of OA patients, and that fat pad volume is greater in subjects with OA. Fat pad volume was measured in sequential magnetic resonance (MR) images taken over one year in a cohort of 15 control and 15 knee OA subjects. No differences were observed in the fat pad volume between the two groups at baseline, 3, 6, or 12 months. In control subjects, no significant correlations were present between any parameters (age, BMI, weight, volume of fat pad at any time point). However, in the osteoarthritic group, fat pad volume was correlated with age at every time point. One possible explanation is that local factors related to knee OA may also induce enlargement of the fat pad with age. Alternatively, subjects who are prone to growth or enlargement of the fat pad may also be more prone to symptomatic OA. These findings provide intriguing preliminary data on the potential role of the infrapatellar fat pad in OA, although additional study is required to better understand the mechanisms of this relationship.

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.

Association of the leptin gene with knee osteoarthritis susceptibility in a Han Chinese population: a case-control study

Previous studies have suggested that leptin works as a key regulator in the pathogenesis of osteoarthritis (OA), and genetic factors modulate OA. This study assessed the contribution of leptin gene (LEP) polymorphism(s) to knee OA among Han Chinese. Three tag single-nucleotide polymorphisms (SNPs) covering all those LEP SNPs of which the minor allele frequencies were over 10% were selected. Study subjects (697 patients and 699 controls) were divided into four groups (underweight, normal weight, overweight and obese) by body mass index (BMI). Allele and genotype frequencies in the three tag SNPs were significantly different in the normal weight and overweight groups. In the normal weight, overweight and obese groups, BMI (P=4.3 × 10(-5), 0.012 and 0.009, respectively) and gender (P=3.5 × 10(-22), 5.1 × 10(-23) and 2.1 × 10(-8), respectively) were effective factors. Age was an independent effective factor in the overweight group (P=0.009). Haplotypes were associated with OA in the normal weight group (CAT, P=0.015) and the overweight group (AGC, P=0.015). Our results suggest an association between LEP and knee OA in the normal weight and overweight groups among Han Chinese.

Relationship between body habitus and joint leptin levels in a knee osteoarthritis population

Synovial fluid (SF) leptin has been shown to have an association with cartilage degeneration. Our objective was to examine the relationship between different measures of body habitus and SF leptin levels in an end-stage knee osteoarthritis (OA) population. Sixty consecutive patients with knee OA were surveyed prior to surgery for demographic data. Body habitus was assessed with the body mass index (BMI), waist circumference (WC), and waist-hip ratio (WHR). SF and serum samples were analyzed for leptin and adiponectin using specific ELISA. Nonparametric correlations and linear regression modeling was used to identify the relationship between the measures of body habitus and SF leptin levels. Females had greater levels of leptin than males in both the serum and SF. Significant correlations were found between SF leptin levels and BMI and WC (R(2) 0.44 and 0.38, respectively; p < 0.05). Regression modeling showed that female gender and WC were independent predictors of a greater SF leptin level independent of age, BMI, and presence of diabetes (p < 0.05). WC may be a more accurate measure of body habitus than BMI in the relationship between the metabolic effects of adipose tissue and OA.

Correlation of synovial fluid leptin concentrations with the severity of osteoarthritis

Leptin is known to play an important role in the pathophysiology of osteoarthritis (OA). This study investigated whether synovial fluid (SF) leptin level is related to the radiographic severity of OA and its role as a quantitative marker for the detection of OA. SF was obtained from 42 OA patients who underwent knee surgery and 10 who had no abnormality of articular cartilage during arthroscopic examination. The progression of OA was classified by Kellgren-Lawrence grading scale. The concentrations of leptin were measured with commercial enzyme-linked-immunosorbent serologic assay kits. Median leptin concentrations in SF were significantly higher in OA patients (median 4.40 ng/ml; range 0.5-15.8) compared to controls (median 2.05 ng/ml; range 1.0-4.6; P = 0.006). SF leptin levels showed significant difference according to the severity of OA (P = 0.0125). Median SF leptin level was highest in stage IV patients (11.1 ng/ml), which was significantly higher compared to all other groups including controls (P < 0.05). Age showed a significant positive correlation with leptin concentrations in OA patients (P < 0.05), but not in controls. These results demonstrate that SF leptin concentrations were closely related to the radiographic severity of OA, suggesting that SF leptin levels could be used as an effective marker for quantitative detection of OA.

Cartilage in normal and osteoarthritis conditions

The preservation of articular cartilage depends on keeping the cartilage architecture intact. Cartilage strength and function depend on both the properties of the tissue and on their structural parameters. The main structural macromolecules are collagen and proteoglycans (aggrecan). During life, cartilage matrix turnover is mediated by a multitude of complex autocrine and paracrine anabolic and catabolic factors. These act on the chondrocytes and can lead to repair, remodeling or catabolic processes like those that occur in osteoarthritis. Osteoarthritis is characterized by degradation and loss of articular cartilage, subchondral bone remodeling, and, at the clinical stage of the disease, inflammation of the synovial membrane. The alterations in osteoarthritic cartilage are numerous and involve morphologic and metabolic changes in chondrocytes, as well as biochemical and structural alterations in the extracellular matrix macromolecules.

Leptin beyond body weight regulation--current concepts concerning its role in immune function and inflammation

Leptin, a 16 kDa non-glycosylated polypeptide produced primarily by adipocytes and released into the systemic circulation, exerts a multitude of regulatory functions including energy utilization and storage, regulation of various endocrine axes, bone metabolism, and thermoregulation. In addition to leptin's best known role as regulator of energy homeostasis, several studies indicate that leptin plays a pivotal role in immune and inflammatory response. Because of its dual nature as a hormone and cytokine, leptin can be nowadays considered the link between neuroendocrine and immune system. The increase in leptin production that occurs during infections and inflammatory processes strongly suggests that this adipokine is a part of the cytokines network which governs inflammatory/immune response and host defence mechanisms. Indeed, leptin plays a relevant role in inflammatory processes involving either innate or adaptive immune responses. Several studies have implicated leptin in the pathogenesis of autoimmune inflammatory conditions such as encephalomyelitis, type I diabetes, bowel inflammation and also articular degenerative diseases such as rheumatoid arthritis and osteoarthritis. Although the mechanisms by which leptin exerts its action as modulator of inflammatory/immune response are likely to be more complex than predicted and far to be completely depicted, there is a general consensus about its pivotal role as pro-inflammatory and immune-modulating agent. Here, we review the most recent advances on leptin biology with a particular attention to its adipokine facet, even though its role as metabolic hormone will be also addressed.

Differential expression of leptin and leptin's receptor isoform (Ob-Rb) mRNA between advanced and minimally affected osteoarthritic cartilage; effect on cartilage metabolism

OBJECTIVE

To investigate leptin's effect on cartilage metabolism and the pathophysiology of osteoarthritis (OA).

METHODS

Messenger RNA (mRNA) expression and protein levels of leptin and leptin's receptor isoforms were measured by real-time reverse transcription-PCR and Western blot in osteoarthritic and normal cartilage. Osteoarthritic cartilage samples were obtained from two locations of the knee (n=11) and hip (n=6); from the main defective area (advanced OA) and from adjacent macroscopically and histological intact regions (minimal OA). Paired serum and synovial fluid (SF) leptin levels were measured. The effect of leptin was evaluated on chondrocyte proliferation, IL-1beta (interleukin-1beta), NO and metalloproteinases 9 and 13 (MMP-9, MMP-13) protein expression.

RESULTS

Leptin's and leptin's receptor (Ob-Rb) expression levels were significantly increased in advanced OA cartilage compared to minimal. Leptin was significantly increased in SF than serum samples. Also, leptin had a detrimental effect on chondrocyte proliferation and induced IL-1beta production and MMP-9 and MMP-13 protein expression. Furthermore, leptin's mRNA expression in advanced OA cartilage was significantly correlated with BMI of the patients.

CONCLUSION

The increased leptin levels in SF point toward a local effect of leptin in articular cartilage, while the observed intrajoint differences of leptin and Ob-Rb mRNA expression may be related to the grade of cartilage destruction. The observed production of IL-1beta, MMP-9 and MMP-13 by chondrocytes after leptin treatment indicates a pro-inflammatory and catabolic role of leptin on cartilage metabolism. Furthermore, the observed correlation of leptin's mRNA expression with BMI suggests that leptin may be a metabolic link between obesity and OA.

The emerging role of adipokines as mediators of inflammation and immune responses

Interest in the biology of white adipose tissue (WAT) has increased dramatically since the discovery of leptin in 1994. The identification of the product of the gene obese (ob) threw light on the role of adipose tissue in the physiopathology of obesity-related diseases, and spurred the identification of numerous other adipokines, many of a pro-inflammatory nature. It has become increasingly evident that WAT-derived cytokines mediate between obesity-related exogenous factors (nutrition and lifestyle) and the molecular events that lead to metabolic syndrome and inflammatory and/or autoimmune conditions. Here, we review recent adipokine research, with particular attention to the roles of leptin, adiponectin, resistin, visfatin, apelin, vaspin and hepcidin in such conditions.

Differences in outcomes of obese women and men undergoing primary total hip arthroplasty

OBJECTIVE

To evaluate the effect of obesity on the incidence of main complications (infection, dislocation, and revision), functional outcome, and patient satisfaction 5 years after primary total hip arthroplasty (THA), and to determine whether results differ between obese women and men.

METHODS

We conducted a hospital-based prospective cohort study including patients who underwent primary THA (2,495 hips) between 1996 and 2005. We used rates and rate ratios to compare the incidence of main complications in obese and nonobese patients, and we stratified the data for sex. Functional outcome was measured using the Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index.

RESULTS

The adjusted incidence rate ratio for infection (obese versus nonobese) was 4.4 (95% confidence interval [95% CI] 1.8, 10.8). Obesity substantially increased the infection rate in women (incidence rate ratio comparing obese with nonobese women 16.1; 95% CI 3.4, 75.7), whereas obesity appeared to have no effect in men (incidence rate ratio 1.0; 95% CI 0.2, 5.3). The adjusted incidence rate ratio for dislocation (obese versus nonobese) was 2.4 (95% CI 1.4, 4.2), with a higher rate increase in obese women. A total of 817 patients had a 5-year clinical followup visit. Functional outcome and satisfaction were slightly lower in obese women partly due to higher complication rates. No difference was seen in men.

CONCLUSION

Primary THA is a successful intervention in obese patients, but physician and patient must be aware of increased complications, particularly in women.