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

Body roundness index and the risk of knee osteoarthritis: evidence from the China Health and Retirement Longitudinal Study

Objective

Previous cross-sectional studies have demonstrated that the body roundness index (BRI) is associated with knee osteoarthritis (KOA). However, no longitudinal studies have confirmed this association. This study aims to explore the link between BRI and KOA risk in the Chinese population through longitudinal analysis and to evaluate its utility in early diagnosis and risk prediction.

Methods

This study utilizes data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 7,318 participants who were followed from 2015 to 2020 were included. BRI was calculated using physical examinations and questionnaire data, and participants were categorized by quartiles. The relationship between BRI and KOA risk was assessed using multivariate weighted regression models and trend tests, while subgroup and sensitivity analyses were conducted to ensure the robustness of the findings.

Results

After 5 years of follow-up, 1,035 participants (14.14%) were diagnosed with KOA. Findings indicate a positive correlation between BRI and KOA risk (HR = 1.08, 95% CI: 1.02-1.13, p = 0.0039), with an increasing trend in KOA risk across BRI quartiles (p for trend = 0.0033). Subgroup analysis reveals that the association is particularly strong among individuals aged 50-59, males, those living in rural areas, and those without cardiovascular disease.

Conclusion

This study establishes that an increase in BRI significantly elevates KOA risk. These findings suggest that BRI could be an effective tool for KOA risk assessment and could contribute to the development of personalized prevention strategies. Additionally, BRI is valuable in elucidating the potential mechanisms linking body fat distribution and inflammatory responses in KOA progression.

Associations between low sex steroid concentrations and incidence of knee and hip replacement for osteoarthritis in community-dwelling older women

OBJECTIVE

To examine whether low circulating sex steroid concentrations are associated with the incidence of knee and hip replacement for osteoarthritis in community-dwelling older women.

STUDY DESIGN

This prospective cohort study examined 5535 Australian women recruited into the Aspirin in Reducing Events in the Elderly (ASPREE) trial, aged ≥70 years, not taking medications affecting sex steroid concentrations, and with sex steroid concentrations measured by liquid chromatography-tandem mass spectrometry.

MAIN OUTCOME MEASURES

The incidence of knee and hip replacement for osteoarthritis was determined by hospitalisations for knee and hip surgical procedures where osteoarthritis was recorded as the indication.

RESULTS

With a mean follow-up of 3.9 (SD 1.4) years, 311 women underwent knee replacement and 242 underwent hip replacement. A greater incidence of knee replacement was observed in women with the lowest quartile concentrations of oestrone (HR 1.35, 95 % CI 1.04-1.75, p = 0.03) and testosterone (HR 1.35, 95 % CI 1.05-1.72, p = 0.02) compared with quartiles 2 to 4, after adjusting for age, body mass index, socioeconomic status, smoking, alcohol consumption, and comorbidities. A greater likelihood of hip replacement was seen for women with the lowest quartile concentrations of dehydroepiandrosterone compared with quartiles 2 to 4 (HR 1.37, 95 % CI 1.03-1.82, p = 0.03).

CONCLUSIONS

Low concentrations of endogenous sex steroids were associated with a greater likelihood of lower-limb joint replacement for osteoarthritis in community-based women aged 70 years or older. These findings suggest sex steroids contribute to musculoskeletal health in later life, although the mechanisms by which sex steroids might influence joint replacement remain unclear.

CLINICALTRIALS

gov NCT01038583. International Standard Randomized Controlled Trial Number Register ISRCTN83772183.

Associations between urinary phytoestrogen mixed metabolites and osteoarthritis risk

BACKGROUND

This study aims to explore the relationship between urinary phytoestrogen mixed metabolites and the risk of osteoarthritis (OA).

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES), a Weighted Quantile Sum (WQS) regression analysis was conducted to determine the dominant metabolites. Additionally, a Bayesian kernel machine regression (BKMR) model was utilized to explore the combined effects of phytoestrogen mixed metabolites on OA.

RESULTS

Compared to the lowest quartile group, the highest quartile group of Enterodiol showed a 46% increased risk of OA (OR = 1.46, 95% CI: 1.09-1.96), while the highest quartile group of Enterlactone showed a 30% decreased risk of OA (OR = 0.70, 95% CI: 0.52-0.96). The WQS regression model analysis revealed a positive relationship between urinary phytoestrogen mixed metabolites and OA risk, with Enterodiol found to have the highest weight in this association. The BKMR model indicated that the association between urinary phytoestrogens and OA increased with concentration but did not reach statistical significance. The univariate exposure-response function demonstrated a positive association between Enterodiol and OA.

CONCLUSIONS

There is a positive relationship between urinary phytoestrogen mixed metabolites and OA, with Enterodiol being an important factor influencing OA risk.

Men and women undergoing total hip arthroplasty have different clinical presentations before surgery and different outcomes at 1-year follow-up

PURPOSE

The purpose of this study was to investigate the influence of sex on patients undergoing total hip arthroplasty (THA) for hip osteoarthritis (HOA), aiming to assess the clinical and functional outcomes using patient-reported outcome measures (PROMs).

METHODS

A retrospective analysis of patients undergoing THA at Ospedale Galeazzi-Sant'Ambrogio between 2016 and 2022 was conducted. Inclusion criteria encompassed Kellgren-Lawrence grade III or IV HOA, with preoperative and 12-month postoperative PROMs. Enroled patients have been selected from a larger cohort without matching design for confounders. The analyses were performed using R software v4.0.3 (R Core Team) and data distributions were assessed using the Shapiro-Wilk normality test.

RESULTS

One hundred ninety patients (72 male and 118 female) who had both preoperative and postoperative PROMs have been analysed from our institutional prosthesis registry (Datareg). Baseline and 12-month post-THA PROMs showed significant improvements overall. VAS score dropped notably from baseline to 3 months postsurgery (7.1 ± 2.1 vs. 0.9 ± 1.7). Functional and mental PROMs, including Harris Hip Score-functional (HHS-F), Harris Hip Score-total (HHS-t), SF-12PS and SF-12MS, exhibited substantial improvements post-THA. Stratifying by sex, males had lower baseline VAS, higher HHS-F, SF-12MS and hip disability and osteoarthritis outcome score-physical function short form (HOOS-PS). At 12 months, males displayed significantly better VAS, HHS-F, SF-12PS and HOOS-PS scores. Complication rates were minimal (1.5%), with stable rates across genders, mostly involving dislocation and periprosthetic fractures. Implant survival at 12 months reached an impressive 99%.

CONCLUSION

THA remains an effective treatment for severe HOA. However, females presented with worse baseline conditions and showed relatively less improvement at 1-year postsurgery compared to males. This difference could be attributed to physiological and psychosocial factors associated with sex, including hormonal changes, muscle mass decline and perception of pain. Longer follow-ups and prospective studies are necessary to validate these findings and facilitate personalised approaches in HOA treatment, emphasising the need for careful consideration of sex-related variables in clinical decision-making for THA patients.

LEVEL OF EVIDENCE

Level III.

The musculoskeletal syndrome of menopause

Fifty-one percent of humans are born with ovaries. As the ovarian production of estrogen diminishes in midlife and ultimately stops, it is estimated that more than 47 million women worldwide enter the menopause transition annually. More than 70% will experience musculoskeletal symptoms and 25% will be disabled by them through the transition from perimenopause to postmenopause. This often-unrecognized collective of musculoskeletal symptoms, largely influenced by estrogen flux, includes arthralgia, loss of muscle mass, loss of bone density and progression of osteoarthritis, among others. In isolation, it can be difficult for clinicians and patients to adequately appreciate the substantial role of decreasing estrogen, anticipate the onset of related symptoms and actively treat to mitigate future detrimental processes. Thus, in this review we introduce a new term, the musculoskeletal syndrome of menopause, to describe the collective musculoskeletal signs and symptoms associated with the loss of estrogen. Given the significant effects of these processes on quality of life and the associated personal and financial costs, it is important for clinicians and the women they care for to be aware of this terminology and the constellation of musculoskeletal processes for which proper risk assessment and prophylactic management are of consequence.

Evaluation of the efficacy after Total Knee Arthroplasty by Gait analysis in patients with Knee Osteoarthritis: a meta-analysis

BACKGROUND

Total knee replacement (TKA) is a frequent modality performed in patients with knee osteoarthritis (OA). The aim of this study was to perform a meta-analysis and systematic review to evaluate the efficacy after TKA by gait analysis in patients with OA.

METHODS

PubMed, EMBASE, the Cochrane library, and Web of Science were searched for relevant studies from inception to July 2024. STATA SE 14.0 software was used for statistical analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guideline.

RESULTS

A total of 2525 reports were identified with 24 studies meeting pre-designed inclusion criteria. Several gait parameters were investigated. In patients with knee OA after TKA, there existed an increase in the Max knee flexion (WMD, 3.12; 95% CI, 0.93 to 5.32; I2 = 73.9%, P < 0.001), the Cadence (WMD, 4.05; 95% CI, 2.28 to 5.82; I2 = 48.9%, P = 0.068), the stride length (WMD, 0.05; 95% CI, 0.01 to 0.09; I2 = 77.1%, P < 0.001), the walking speed (WMD, 0.08; 95% CI, 0.02 to 0.14; I2 = 93.3%, P < 0.001), and the step length (WMD, 0.04; 95% CI, 0.00 to 0.07; I2 = 89.3%, P < 0.001) while a decrease in the double support time (WMD, -0.04; 95% CI, - 0.08 to -0.01; I2 = 0.0%, P = 0.585). Besides, no statistically significant differences were observed in the Knee range of motion (ROM), the Max knee rotation at stance phase, the Max knee extension, the step width, the stride time and the step time. Sensitivity analysis showed that all the results were robust.

CONCLUSIONS

In summary, the study found that, in patients with knee OA undergoing TKA may have great effects on improving gait parameters. If there are more high-quality studies in the future, we should make a more comprehensive evaluation of walking function by gait analysis together with other evaluation systems such as muscle strength and proprioception measurement.

Effect of biological sex and short-term high-fat diet on cellular proliferation, ribosomal biogenesis, and targeted protein abundance in murine articular cartilage

Objective

To identify factors contributing to sex-differences in OA risk by evaluating the short-term effect of high-fat (HF) diet on sex-specific changes in cartilage cell proliferation, ribosomal biogenesis, and targeted extra-cellular and cellular protein abundance.

Materials and methods

Knee cartilage was harvested to the subchondral bone from 20-week-old female and male C57BL/6J mice fed a low-fat or HF diet for 4 weeks and labeled with deuterium oxide for 1, 3, 5, 7, 15, or 21 days. Deuterium enrichment was quantified in isolated DNA and RNA to measure cell proliferation and ribosomal biogenesis, respectively. Protein concentration was measured using targeted high resolution accurate mass spectrometry.

Results

HF diet increased the maximal deuterium incorporation into DNA from approximately 40 to 50%, albeit at a slower rate. These findings, which were magnified in female versus male mice, indicate a greater number of proliferating cells with longer half-lives under HF diet conditions. HF diet caused distinct sex-dependent effects on deuterium incorporation into RNA, increasing the fraction of ribosomes undergoing biogenesis in male mice and doubling the rate of ribosome biogenesis in female mice. HF diet altered cartilage protein abundance similarly in both sexes, except for matrilin-3, which was more abundant in HF versus LF conditions in female mice only. Overall, HF diet treatment had a stronger effect than sex on cartilage protein abundance, with most changes involving extracellular matrix and matrix-associated proteins.

Conclusions

Short-term HF diet broadly altered cartilage matrix protein abundance, while sex-dependent effects primarily involved differences in cell proliferation and ribosomal biogenesis.

Increased alcohol intake is associated with radiographic severity of knee and hand osteoarthritis in men

Observational studies have shown controversial associations between alcohol intake and radiographic osteoarthritis (OA). This study investigated whether this association was causal using a Mendelian randomization (MR) study in a population-based cohort in Korean. The study enrolled 2429 subjects (1058 men, 1371 women) from the Dong-gu Study. X-rays of the hand and knee joints were scored using a semi-quantitative grading system to calculate the total score of the hand and knee joints. ALDH2 rs671 genotyping was performed by high-resolution melting analysis. MR instrumental variable analysis and observational multivariable regression analysis were used to estimate the association between genetically predicted alcohol intake and the radiographic severity of OA. Subjects with the G/G genotype had a higher current alcohol intake than those with the G/A and A/A genotypes in both men and women (all P < 0.001). Men with the G/G genotype had higher total knee (P < 0.001) and hand scores (P = 0.042) compared to those with the G/A and A/A genotypes after adjusting for age and body mass index, but not in women. In the observational multivariable regression analysis, each alcohol drink per day in men was associated with increased knee (P = 0.001) and hand joint scores (P = 0.013) after adjustment, but not in women. In our MR analysis, utilizing ALDH2 rs671 genotypes as instrumental variables for alcohol consumption, has shown a significant link between each additional daily alcohol drink and increased radiographic joint severity in men.

Female obesity: clinical and psychological assessment toward the best treatment

Obesity is a heterogeneous condition which results from complex interactions among sex/gender, sociocultural, environmental, and biological factors. Obesity is more prevalent in women in most developed countries, and several clinical and psychological obesity complications show sex-specific patterns. Females differ regarding fat distribution, with males tending to store more visceral fat, which is highly correlated to increased cardiovascular risk. Although women are more likely to be diagnosed with obesity and appear more motivated to lose weight, as confirmed by their greater representation in clinical trials, males show better outcomes in terms of body weight and intra-abdominal fat loss and improvements in the metabolic risk profile. However, only a few relatively recent studies have investigated gender differences in obesity, and sex/gender is rarely considered in the assessment and management of the disease. This review summarizes the evidence of gender differences in obesity prevalence, contributing factors, clinical complications, and psychological challenges. In addition, we explored gender differences in response to obesity treatments in the specific context of new anti-obesity drugs.

Association of synovial fluid and urinary C2C-HUSA levels with surgical outcomes post-total knee arthroplasty

OBJECTIVES

After total knee arthroplasty (TKA), ∼30% of knee osteoarthritis (KOA) patients show little symptomatic improvement. Earlier studies have correlated urinary (u) type 2 collagen C terminal cleavage peptide assay (C2C-HUSA), which detects a fragment of cartilage collagen breakdown, with KOA progression. This study determines whether C2C levels in urine, synovial fluid, or their ratio, are associated with post-surgical outcomes.

METHODS

From a large sample of 489 subjects, diagnosed with primary KOA undergoing TKA, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scores were collected at baseline (time of surgery) and one-year post-TKA. Baseline urine (u) and synovial fluid (sf) were analysed using the IBEX-C2C-HUSA assay, with higher values indicating higher amounts of cartilage degradation. For urine, results were normalised to creatinine. Furthermore, subjects' changes in WOMAC scores were categorised based on percent reduction in pain or improvement in function, compared to baseline, such that >66.7%, >33.3 to ≤66.7%, and ≤33.3% denoted "strong", "moderate" and "mild/worse" responses, respectively. Associations of individual biofluid C2C-HUSA levels, or their ratio, with change in WOMAC pain and function scores up to one-year post-TKA, or category of change, were analysed by linear, logistic, or cumulative odds models.

RESULTS

Higher baseline uC2C-HUSA levels or a lower ratio of baseline sfC2C-HUSA to uC2C-HUSA were associated with improvements in WOMAC pain by linear multivariable modelling [odds ratio -0.40 (95% confidence interval -0.76, -0.05) p = 0.03; 0.36 (0.01, 0.71), p = 0.04, respectively], while sfC2C-HUSA alone was not. However, lower ratios of sfC2C-HUSA to uC2C-HUSA were associated with improvements in WOMAC function [1.37 (0.18, 2.55), p = 0.02], while sfC2C-HUSA and uC2C-HUSA alone were not. Lower ratios of sfC2C-HUSA to uC2C-HUSA were also associated with an increased likelihood of a subject being categorised in a group where TKA was beneficial in both univariable [pain, 0.81 (0.68, 0.96), p = 0.02; function, 0.92 (0.85, 0.99), p = 0.035] and multivariable [pain, 0.81 (0.68, 0.97) p = 0.02; function, 0.92 (0.85, 1.00), p = 0.043] ordinal modelling, while sfC2C-HUSA and uC2C-HUSA alone were not.

CONCLUSIONS

Overall, ratios of baseline sfC2C-HUSA to uC2C-HUSA, and baseline uC2C-HUSA, may play an important role in studying post-TKA surgical outcomes.

The Prevalence of Knee Osteoarthritis and Its Association With Obesity Among Individuals in Saudi Arabia

Introduction This research, set in 2023 in Saudi Arabia, addresses the rising prevalence of knee osteoarthritis (OA) among obese individuals. It explores associations with age, BMI, and gender, aiming to enhance our understanding of this pressing health issue within the Saudi context and contribute to global research on OA and obesity. Methodology A retrospective cohort study was conducted at King Saud Hospital and Buraydah Central Hospital in the Al-Qassim region from November 2022 to February 2023. It included the patients' records that fit the inclusion criteria during the study period. A data collection sheet was used to collect data, and data was analyzed using SPSS Statistics version 27.0.1 (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY: IBM Corp.). Results In 2023, a study on knee OA among 267 obese individuals in Saudi Arabia yielded significant findings. The median age of participants was 60 years, with an average weight of 77.00 kg (IQR:15) and a median BMI of 29.14, categorizing participants as overweight. Ninety percent (n=240) of knee OA cases occurred in individuals classified as "obese" (n=118) or "overweight (n=122)". Furthermore, OA primarily affected both knees in 79.4% (n=212) of cases. Conclusion Study participants, predominantly older and female, reflect OA's age-related and gender-specific prevalence trends. Notably, excess weight and a higher BMI highlight the role of obesity as a significant OA risk factor. Bilateral knee involvement is common, with a strong link between OA and obesity.

Hysterectomy and risk of osteoarthritis in women: a nationwide nested case-control study

OBJECTIVE

Hysterectomy is the most common gynaecological surgery, performed mainly for benign uterine pathologies in women. Studies have suggested that hysterectomy is associated with osteoarthritis (OA); however, the association remains controversial. This study aimed to investigate the association between hysterectomy and the risk of OA.

METHOD

We performed a population-based nested case-control study using the National Health Insurance programme database from 2000 to 2016 in Taiwan. All medical conditions for each case and control were categorized using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and ICD-10. A multiple conditional logistic regression model was applied to analyse the adjusted odds ratio (aOR) and 95% confidence interval (CI) for the association between hysterectomy and OA.

RESULTS

Our analyses included 16 592 patients with OA and 66 368 matched controls. After adjustment for possible confounders, hysterectomy had a significant association with OA (aOR = 1.19, 95% CI = 1.09-1.30), especially knee OA (aOR = 1.25, 95% CI = 1.13-1.38). Furthermore, women who received oestrogen therapy (ET) alone and patients who underwent hysterectomy without ET showed a greater risk of OA development compared to women who did not receive ET (aOR = 1.14, 95% CI = 1.07-1.23, and aOR = 1.19, 95% CI = 1.08-1.31, respectively).

CONCLUSION

Our findings indicate that hysterectomy is associated with OA, especially knee OA. We also found that women who received ET alone and patients who underwent hysterectomy without ET had an increased risk of OA.

Effects of Greenshell™ mussel intervention on biomarkers of cartilage metabolism, inflammatory markers and joint symptoms in overweight/obese postmenopausal women: A randomized, double-blind, and placebo-controlled trial

Objective

To investigate the effect of whole greenshell mussel (GSM) powder on biomarkers of cartilage metabolism, inflammatory cytokines, and joint symptoms in postmenopausal women with overweight/obesity and joint discomfort.

Design

Fifty-five postmenopausal women with overweight/obesity were randomly assigned to receive 3 g/day whole GSM powder or placebo for 12 weeks. Cartilage turnover biomarkers urinary C-telopeptide of type II collagen (CTX-II) and serum cartilage oligomeric matrix protein (COMP) were measured at baseline, week 6 and 12. Plasma cytokines were measured at baseline and week 12. Joint pain and knee-related problems were assessed at baseline and week 12 using a 100 mm Visual Analogue Scale (VAS) and the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire, respectively.

Results

Forty-nine participants completed the study (GSM n = 25, placebo n = 24). After 12 weeks, urinary CTX-II showed no significant change over time or between the groups (interaction effect P = 0.1). However, in women with symptomatic knees, a significant difference was noted between the group (treatment effect P = 0.04), as it was lower in the GSM group compared to placebo group at week 6 (P = 0.04) and week 12 (P = 0.03). Serum COMP and plasma cytokines were not affected. GSM supplementation showed greater reduction in the VAS pain score than placebo (-13.2 ± 20.3 vs. -2.9 ± 15.9; P = 0.04). No significant change in KOOS domains between the two groups was observed.

Conclusion

Oral supplementation of whole GSM powder at 3 g/day may slow down the degradation of type II collagen in postmenopausal women with symptomatic knees. GSM treatment conferred clinical benefit on overall joint pain. No significant effect was noted for inflammatory cytokines, suggesting that GSM may act within the joint microenvironment rather than at the systemic level.

Clinical trial registration

[www.australianclinicaltrials.gov.au/clinical-trialregistries], identifier [ACTRN12620000413921p].

Gender differences in the decision-making process for undergoing total knee replacement

OBJECTIVE

To assess gender differences in the decision-making process for treatment of knee osteoarthritis (OA).

METHODS

A secondary analysis of a randomized trial was conducted (n = 193). Knowledge of OA and total knee replacement (TKR), decisional conflict, satisfaction with the decision-making process, treatment preference and TKR uptake 6 months later were compared by gender. Multivariate regression models were developed to identify gender-specific predictors.

RESULTS

Women showed less knowledge (MD = -7.68, 95% CI: -13.9, -1.46, p = 0.016), reported less satisfaction (MD = -6.95, 95% CI: -11.7, -2.23, p = 0.004) and gave more importance to avoiding surgery (U = 2.09, p = 0.019). In women, more importance attributed to the time needed to relieve symptoms significantly reduced the odds of surgery (OR = 0.76, p = 0.016).

CONCLUSION

The provision of information and/or promotion of shared decision-making could be of lower quality in female patients, although other explanations such as differences in information needs or preference for involvement in decision-making cannot be ruled out with the current evidence. Given the study's limitations, especially regarding the sample size, further confirmation is needed.

PRACTICE IMPLICATIONS

A systematic, shared decision-making approach in consultation is needed to avoid potential gender-based biases.

Risk of Postoperative Stiffness Following Multiligamentous Knee Injury Surgery Is Not Affected by Obesity: A Multicenter Study

PURPOSE

The purpose of this study was to examine the relationship between obesity and postoperative stiffness following surgical management of multiligamentous knee injuries (MLKIs) using a large two-center cohort, by both 1) using binary cutoffs at various body mass indexes (BMIs) and 2) a linear regression model.

METHODS

190 consecutive patients who underwent surgical management of MLKIs between January 2001 and March 2020 were reviewed at two level 1 academic trauma centers. Patient demographics, surgical characteristics, and manipulation under anesthesia (MUA)/lysis of adhesions (LOA) were reviewed. Patients were stratified by obesity grades: grade 1 (BMI 30 to <35) grade 2 (BMI 35 to <40); grade 3 (BMI >40), and compared with a nonobese comparison group with BMI <30. Multivariate logistic regressions were performed, including the covariates of age, gender, BMI, acute versus chronic injury, external fixator, vascular injury, knee dislocation, and Schenck Classification. Fisher's exact test was used to compare rate of MUA between grades of obesity. Analyses were performed with R. Statistical significance was set at P < .05.

RESULTS

The mean BMI of the cohort was 29.2 kg/m². The mean overall follow-up was 27.2 ± 7.2 months (range: 14-142 months). There were 55 (29.1%) MUA procedures observed at a mean 3.77 ± 2.18 months (range: 1.8-9.7 months) after final MLKI surgery. No significant difference was found in BMI of patients who underwent a MUA compared to patients who did not (30.2 vs 28.8; P = .67). There was no significant difference in rate or time to MUA following MLKI surgery between groups, with logistic regression demonstrating no significance (P = .144). Use of external fixation at the index surgery (OR = 3.3 [95% CI: 2.2, 4.7; P < .0001]) and vascular injury (OR = 6.2 [95% CI: 1.8, 24.5; P = .005]) were found to be independent predictors for need for MUA.

CONCLUSION

No difference in risk for postoperative stiffness requiring MUA following surgery for MLKI was found based on BMI. At all BMI levels, there were no significant increase in need for postoperative MUA, suggesting at minimum a neutralizing effect of obesity on postoperative stiffness. In addition, patients with external fixator use and vascular injury at index surgery were found to be at significantly higher risk for postoperative stiffness requiring MUA following surgery for MLKI. Surgeons should be aware of the risk factors for arthrofibrosis when proceeding with surgical repair or reconstruction of two or more ligaments of the knee.

LEVEL OF EVIDENCE

III, multicenter retrospective cohort study.

Sex Differences in Functional Capacity in Older Adults With Stroke: An Analysis of Data From the National Health and Aging Trends Study

OBJECTIVE

Women experience greater disability following stroke, but biological sex differences in both overall and specific domains of functional capacity are not well understood. The primary objective of this study was to examine sex differences in overall functional capacity (Short Physical Performance Battery [SPPB] score) cross-sectionally and longitudinally over a 3-year follow-up period. The secondary objective was to determine whether sex differences exist in specific domains of functional capacity of walking speed and lower extremity functional strength.

METHODS

This study was a secondary analysis of data of individuals with stroke from the National Health and Aging Trends Study. For the cross-sectional analyses, general linear models were used to examine differences between 293 men and 427 women in SPPB, walking speed, and the 5-Times Sit-to-Stand Test (5XSST). For the longitudinal analysis, survey-weighted, multivariable-adjusted generalized linear mixed models were used to compare 3-year trajectories in SPPB scores between the sexes (87 men, 153 women).

RESULTS

Women had lower SPPB scores at baseline (difference = 0.9, linearized SE = 0.3) and over 3 years. SPPB scores declined similarly between men and women. Women had lower walking speed (difference = 0.08 m/s, SE = 0.02) as compared with men, but men and women had similar 5XSST scores (difference = 0.6 seconds, SE = 0.5).

CONCLUSION

Older women with stroke have clinically meaningfully lower overall functional capacity as compared with older men but decline at a similar rate over time. Walking speed was lower in older women with stroke, but similar between sexes in 5XSST.

IMPACT

Women with stroke have poorer functional capacity compared with men, which reinforces the importance of targeted stroke rehabilitation strategies to address these sex-specific disparities.

LAY SUMMARY

Women with stroke have poorer outcomes in terms of their ability to move around the community when compared with men. However, both men and women with stroke have similar physical functioning over time.

Effects of the Leptin-Mediated MAPK/ERK Signaling Pathway on Collagen II Expression in Knee Cartilage of Newborn Male Mice from Obese Maternal Offspring

Epidemiological data suggest that various noncommunicable diseases develop as a result of altered maternal metabolic and physiological status due to exposure to several adverse factors during pregnancy. However, evidence for intrauterine exposure factors and mechanisms underlying the origin of early cartilage disease in chronic osteoarthritic disease is still lacking. In this study, we found that persistent overnutrition during pregnancy in obese mothers led to cartilage damage in neonatal male mice. This was mainly characterized by increased apoptosis with decreased expression of chondrocyte collagen II and low expression of Runx family transcription factor 2 (RUNX2) and SRY-box transcription factor 9 (SOX9). This reduction was also found to be associated with high leptin expression in newborn male mice of obese maternal offspring. Furthermore, the administration of leptin and mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK) inhibitors in primary chondrocytes showed that leptin mediated MAPK/ERK signaling activation and thus affected the key regulators of cartilage matrix metallopeptidase 1 (MMP1) and tissue inhibitor of metalloproteinase 1 (TIMP1), thereby altering the expression of collagen II in mouse cartilage. Altogether, this study provided insights into the molecular mechanisms of cartilage-related disease development and also new clues and evidence for the fetogenetic origin of cartilage diseases.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Additive Interaction of Work-Related Stress and Sleep Duration on Arthritis Among Middle-Aged Civil Servants

Aim

Occupational strain is recognized as a risk for arthritis, yet little is known about how psychological stress affects arthritis moderated by sleep duration. The objective of this study is to assess work-related stress using the effort-reward imbalance (ERI) model and the job-demand-support (JDS) model on arthritis moderated by sleep duration.

Methods

A nationwide cross-sectional study randomly collected a total of 11,875 middle-aged, employed civil servants from 647 registered governmental institutions. Each participant anonymously and voluntarily filled out a web-based questionnaire and informed consent at the time of the study. Psychosocial work stress was assessed by ERI and JDS measured by a Chinese version of the job content questionnaire.

Results

There were significant odds ratios (ORs) of arthritis positively associated with high ERI (OR = 1.58), high overcommitment (OC) (OR = 1.57), and job demand (OR = 1.31) and negatively associated with job support (OR = 0.69) using multivariate analysis after being adjusted for covariates. For the short sleep duration group, there was an interaction effect of both high ERI and OC on arthritis, with a synergy index of 18.91 and 1.52, respectively. Similarly, there are high ORs of arthritis in both the high job demand and low job support groups.

Conclusion

Work-related stress related to arthritis moderated by sleep duration for civil servants. Civil servants with high job demand and low job support should use caution to reduce the risk of arthritis.

Osteoarthritis Affects Mammalian Oogenesis: Effects of Collagenase-Induced Osteoarthritis on Oocyte Cytoskeleton in a Mouse Model

Known as a degenerative joint disorder of advanced age affecting predominantly females, osteoarthritis can develop in younger and actively working people because of activities involving loading and injuries of joints. Collagenase-induced osteoarthritis (CIOA) in a mouse model allowed us to investigate for the first time its effects on key cytoskeletal structures (meiotic spindles and actin distribution) of ovulated mouse oocytes. Their meiotic spindles, actin caps, and chromatin were analyzed by immunofluorescence. A total of 193 oocytes from mice with CIOA and 209 from control animals were obtained, almost all in metaphase I (M I) or metaphase II (MII). The maturation rate was lower in CIOA (26.42% M II) than in controls (55.50% M II). CIOA oocytes had significantly larger spindles (average 37 μm versus 25 μm in controls, p < 0.001), with a proportion of large spindles more than 64% in CIOA versus up to 15% in controls (p < 0.001). Meiotic spindles were wider in 68.35% M I and 54.90% M II of CIOA oocytes (mean 18.04 μm M I and 17.34 μm M II versus controls: 11.64 μm M I and 12.64 μm M II), and their poles were approximately two times broader (mean 6.9 μm) in CIOA than in controls (3.6 μm). CIOA oocytes often contained disoriented microtubules. Actin cap was visible in over 91% of controls and less than 20% of CIOA oocytes. Many CIOA oocytes without an actin cap had a nonpolarized thick peripheral actin ring (61.87% of M I and 52.94% of M II). Chromosome alignment was normal in more than 82% in both groups. In conclusion, CIOA affects the cytoskeleton of ovulated mouse oocytes—meiotic spindles are longer and wider, their poles are broader and with disorganized fibers, and the actin cap is replaced by a broad nonpolarized ring. Nevertheless, meiotic spindles were successfully formed in CIOA oocytes and, even when abnormal, allowed correct alignment of chromosomes.

Gender and Sex Are Key Determinants in Osteoarthritis Not Only Confounding Variables. A Systematic Review of Clinical Data

Many risk factors for osteoarthritis (OA) have been noted, while gender/sex differences have been understated. The work aimed to systematically review literature investigating as primary aim the relationship between gender/sex related discriminants and OA. The search was performed in PubMed, Science Direct and Web of Knowledge in the last 10 years. Inclusion criteria were limited to clinical studies of patients affected by OA in any joints, analyzing as primary aim gender/sex differences. Exclusion criteria were review articles, in vitro, in vivo and ex vivo studies, case series studies and papers in which gender/sex differences were adjusted as confounding variable. Of the 120 records screened, 42 studies were included. Different clinical outcomes were analyzed: morphometric differences, followed by kinematics, pain, functional outcomes after arthroplasty and health care needs of patients. Women appear to use more health care, have higher OA prevalence, clinical pain and inflammation, decreased cartilage volume, physical difficulty, and smaller joint parameters and dimensions, as compared to men. No in-depth studies or mechanistic studies analyzing biomarker differential expressions, molecular pathways and omic profiles were found that might drive preclinical and clinical research towards sex-/gender-oriented protocols.

S-Equol Protects Chondrocytes against Sodium Nitroprusside-Caused Matrix Loss and Apoptosis through Activating PI3K/Akt Pathway

Osteoarthritis (OA) is a common chronic disease with increasing prevalence in societies with more aging populations, therefore, it is causing more concern. S-Equol, a kind of isoflavones, was reported to be bioavailable and beneficial to humans in many aspects, such as improving menopausal symptoms, osteoporosis and prevention of cardiovascular disease. This study investigated the effects of S-Equol on OA progress in which rat primary chondrocytes were treated with sodium nitroprusside (SNP) to mimic OA progress with or without the co-addition of S-Equol for the evaluation of S-Equol's efficacy on OA. Results showed treatment of 0.8 mM SNP caused cell death, and increased oxidative stress (NO and H₂O₂), apoptosis, and proteoglycan loss. Furthermore, the expressions of MMPs of MMP-2, MMP-3, MMP-9, and MMP-13 and p53 were increased. The addition of 30 μM S-Equol could lessen those caused by SNP. Moreover, S-Equol activates the PI₃K/Akt pathway, which is an upstream regulation of p53 and NO production and is associated with apoptosis and matrix degradation. As a pretreatment of phosphoinositide ₃-kinases (PI₃K) inhibitor, all S-Equol protective functions against SNP decrease or disappear. In conclusion, through PI₃K/Akt activation, S-Equol can protect chondrocytes against SNP-induced matrix degradation and apoptosis, which are commonly found in OA, suggesting S-Equol is a potential for OA prevention.

Abortion is associated with knee osteoarthritis among older women in China: A STROBE-compliant article

The current studies revealed inconsistent relationship between reproductive factors and osteoarthritis. Community-based research has not been conducted in China. The study was to examine the association of reproductive factors with the prevalence of knee osteoarthritis (OA).Through a multistage stratified random sampling method, 10 streets or villages from 5 cities in Hunan province were randomly selected, a total 2746 eligible women aged 50 to 83 were recruited in this cross-sectional study. A structured questionnaire including demographic factors, socio-economic status, reproductive factors, and knee OA was used. According to the criteria of American College of Rheumatology, clinical knee OA was assessed by doctors in community or village health clinics for knee pain, age, morning stiffness, crepitus on active motion or for knee pain, morning stiffness, crepitus on active motion, and tenderness of the bony navigation of the joint. Self-reported age of menarche, parity, abortion history, and menopausal status were collected.The prevalence of knee OA was 13.44%. Abortion is associated with knee OA (odds ratio [OR] = 1.271, 95% confidence interval [CI] = 1.007, 1.606), but age at menarche, parity, and menopausal status were not the factors. Furthermore, age (OR = 1.040, 95% CI = 1.020, 1.060), weight (OR = 1.019, 95% CI = 1.004, 1.035), higher education level (OR = 1.530, 95% CI = 1.121, 2.088), higher monthly household income (OR = .583, 95% CI = 0.441, 0.770 for 3000-4999 ¥ and OR = 0.599, 95% CI = 0.431, 0.833 for 5000 ¥ or more), and chronic gastritis (OR = 3.364, 95% CI = 2.548, 4.442) were associated with knee OA.Abortion may increase the risk of knee OA. Special attention should be paid to women with a history of abortion, and women who are planning to abort should be informed of the risk of knee OA later in life. The relationship between abortion and knee OA should be interpreted with caution and further confirmed.

Burden of osteoarthritis in China, 1990-2017: findings from the Global Burden of Disease Study 2017

BACKGROUND

China has seen a remarkable epidemiological and demographic transition during the past three decades. We aimed to describe the prevalence of osteoarthritis as well as years lived with disability (YLDs) due to osteoarthritis in China, according to age, sex, and geographical location, from 1990 to 2017.

METHODS

Data were obtained from systematic reviews of symptomatic osteoarthritis of the knee and hip in the Global Burden of Diseases, Injuries, and Risk Factors Study 2017 (GBD 2017). Three categories of sequelae (mild, moderate, and severe) of osteoarthritis were defined to indicate the degrees of severity and functional loss associated with the condition. A Bayesian meta-regression tool was applied to estimate the prevalence of osteoarthritis and the distribution of its severity. YLDs were calculated by multiplying the prevalence of osteoarthritis sequelae by their corresponding disability weights. All data were analysed by age-sex-province-year groups in China.

FINDINGS

Around 26·1 million individuals in China had osteoarthritis in 1990, and this number rose to 61·2 million in 2017. The age-standardised prevalence of osteoarthritis increased from 2·9% (95% uncertainty interval 2·5-3·3) in 1990 to 3·1% (2·7-3·4) in 2017. The total YLDs due to osteoarthritis increased from 0·84 million (0·42-1·69) in 1990 to 1·97 million (0·98-3·94) in 2017, while the age-standardised YLD rate increased from 92·5 (45·7-185·6) per 100 000 people to 98·8 (49·4-197·6) per 100 000. Osteoarthritis prevalence and YLDs were higher in females than in males, and YLD rate increased with age. Osteoarthritis was the 24th most common cause of YLDs in China in 2017, accounting for 1·08% (0·64-2·02) of all YLDs.

INTERPRETATION

Osteoarthritis is prevalent in China. Between 1990 and 2017, disease burden increased and varied greatly according to geographical location. Appropriate prevention and treatment strategies, predominantly those targeted at women, older people, and underdeveloped areas, must be developed to reduce the burden of the disease.

FUNDING

National Natural Science Foundation of China, China National Key Research and Development Programme.

The association between body mass index and the risk of endometriosis: A meta-analysis

Background:

Many epidemiologic studies have been conducted to assess factors that were associated to endometriosis, but there is no consistency in results. Therefore, we conducted this meta-analysis to investigate the association between body mass index and the risk of endometriosis.

Methods:

In this meta-analysis, relevant studies that published in major international electronic bibliographic databases of PubMed, Scopus and Web of Science were systematically searched during November 2017. The Begg and Egger’s test was used to investigate publication bias in included studies. The Q-statistic and I2 tests were carried out for measuring heterogeneity. The random-effects model was conducted to obtain pooled odds ratio.

Results:

Our results showed a direct association between underweight and endometriosis in woman (odds ratio = 1.41, 95% confidence interval = 1.16–1.66), so underweight woman had 41% higher chance for endometriosis. However, we did not find linear association between overweight and endometriosis (odds ratio = 0.95; 95% confidence interval: 0.72–1.18) and obesity and endometriosis (odds ratio = 0.88; 95% confidence interval: 0.54–1.21), respectively.

Conclusions:

Our results suggested that underweight was a risk factor for the endometriosis, while overweight and obesity were not protective factors for endometriosis.

Biochanin-A antagonizes the interleukin-1β-induced catabolic inflammation through the modulation of NFκB cellular signaling in primary rat chondrocytes

Biochanin-A, a phytoestrogen derived from herbal plants, protected from the IL-1β-induced loss of proteoglycans through the suppression of matrix degrading enzymes such as matrix metalloproteinase (MMP)-13, MMP-3, MMP-1, and ADAMTS-5 in primary rat chondrocytes and the knee articular cartilage. It also suppressed the expression of IL-1β-induced catabolic factors such as nitric oxide synthase 2, cyclooxygenase-2, prostaglandin E2, and inflammatory cytokines. Furthermore, biochanin-A suppressed the IL-1β-induced phosphorylation of NFκB, and inhibited its nuclear translocation in primary rat chondrocytes. These results indicate that biochanin-A antagonizes the IL-1β-induced catabolic effects through its anti-inflammatory activity that involves the modulation of NFκB signaling.

Men and Women Demonstrate Differences in Early Functional Recovery After Total Knee Arthroplasty

OBJECTIVE

To investigate whether sex affects the trajectory of functional recovery after total knee arthroplasty (TKA).

DESIGN

Retrospective analysis from a historical database containing data from 3 prospective clinical trials and a pilot study.

SETTING

Clinical laboratory setting.

PARTICIPANTS

Recruitment across studies was restricted to patients who underwent an elective unilateral TKA for the treatment of osteoarthritis and were between 50 and 85 years of age (N=301).

INTERVENTIONS

Across all 4 studies, patients received a TKA and physical therapy intervention. Measures of physical function and strength were assessed before TKA and 1, 3, and 6 months after TKA.

MAIN OUTCOME MEASURES

Using a repeated-measures maximum likelihood model, statistical inference was made to estimate the changes in outcomes from before surgery to 1, 3, and 6 months after TKA that were stratified by sex. Muscle strength was assessed during maximal isometric quadriceps and hamstrings contractions. Muscle activation was assessed in the quadriceps muscle. Physical function outcomes included timed Up and Go (TUG) test, stair climbing test, and 6-minute walk test (6MWT).

RESULTS

Women demonstrated less decline in quadriceps strength than did men at 1, 3, and 6 months after TKA (P<.04), whereas women demonstrated less decline in hamstrings strength 1 month after TKA (P<.0001). Women demonstrated a greater decline than did men on the TUG test (P=.001), stair climbing test (P=.004), and 6MWT (P=.001) 1 month after TKA. Sex differences in physical function did not persist at 3 and 6 months after TKA.

CONCLUSIONS

Sex affected early recovery of muscle and physical function in the first month after TKA. Women demonstrated better preservation of quadriceps strength but a greater decline on measures of physical function than did men.

Measurement of pain and anthropometric parameters in women with chronic pelvic pain

RATIONALE, AIMS AND OBJECTIVES

To analyse anthropometric parameters, clinical pain and experimental pain in women with chronic pelvic pain (CPP).

METHODS

Ninety-one women with a clinical diagnosis of CPP, mean age of 40.03 ± 9.97 years, submitted to anthropometric evaluation based on body mass index (BMI) and percent body fat (%BF) using bioimpedance body composition monitor; pain intensity was determined by visual analogue scale (VAS), numerical categorical scale (NCS) and McGill Pain Questionnaire; experimental pain was determined by transcutaneous electrical nerve stimulation (TENS), and anxiety and depression symptoms were determined by the Hospital Anxiety and Depression scale.

RESULTS

A total of 54.8% of the women showed %BF >32 risk of disease associated with obesity. Regarding the anthropometric data, a statistically significant difference was observed between groups for both BMI and %BF (P<0.0001). In the analysis of pain intensity by the VAS, NCS and total McGill, there was no significant difference between the groups, and experimental pain by TENS revealed significant difference only between the normal weight and overweight groups (P=0.0154). The results of anxiety symptoms were above the cut-off point in all groups, with no significant difference between them (P=0.3710). The depression symptoms were below the cut-off point in the normal weight group and above the cut-off point in the overweight and obese groups, 9.469(4.501) and 9.741(4.848), respectively, with no significant difference between them (P=0.6476).

CONCLUSION

Evaluation of anthropometric parameters and pain measurements can be applied in clinical practice, making a contribution to the diagnosis and influencing the choice of a more effective treatment for women with CPP.

Chondrocyte and mesenchymal stem cell-based therapies for cartilage repair in osteoarthritis and related orthopaedic conditions

Osteoarthritis (OA) represents a final and common pathway for all major traumatic insults to synovial joints. OA is the most common form of degenerative joint disease and a major cause of pain and disability. Despite the global increase in the incidence of OA, there are no effective pharmacotherapies capable of restoring the original structure and function of damaged articular cartilage. Consequently cell-based and biological therapies for osteoarthritis (OA) and related orthopaedic disorders have become thriving areas of research and development. Autologous chondrocyte implantation (ACI) has been used for treatment of osteoarticular lesions for over two decades. Although chondrocyte-based therapy has the capacity to slow down the progression of OA and delay partial or total joint replacement surgery, currently used procedures are associated with the risk of serious adverse events. Complications of ACI include hypertrophy, disturbed fusion, delamination, and graft failure. Therefore there is significant interest in improving the success rate of ACI by improving surgical techniques and preserving the phenotype of the primary chondrocytes used in the procedure. Future tissue-engineering approaches for cartilage repair will also benefit from advances in chondrocyte-based repair strategies. This review article focuses on the structure and function of articular cartilage and the pathogenesis of OA in the context of the rising global burden of musculoskeletal disease. We explore the challenges associated with cartilage repair and regeneration using cell-based therapies that use chondrocytes and mesenchymal stem cells (MSCs). This paper also explores common misconceptions associated with cell-based therapy and highlights a few areas for future investigation.

The future of osteoarthritis therapeutics: targeted pharmacological therapy

Osteoarthritis (OA) is one of the most common forms of degenerative joint disease and a major cause of pain and disability affecting the aging population. It is estimated that more than 20 million Americans and 35 to 40 million Europeans suffer from OA. Analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) are the only therapeutic treatment options for OA. Effective pharmacotherapy for OA, capable of restoring the original structure and function of damaged cartilage and other synovial tissue, is urgently needed, and research into such disease-modifying osteoarthritis drugs (DMOADs) is in progress. This is the first of three reviews focusing on OA therapeutics. This paper provides an overview of current research into potential structure-modifying drugs and more appropriately targeted pharmacological therapy. The challenges and opportunities in this area of research and development are reviewed, covering the most up-to-date initiatives, trends, and topics.

Perinatal exposure to 4-nonylphenol affects adipogenesis in first and second generation rats offspring

Maternal exposure to 4-nonylphenol (4-NP) during pregnancy was shown to alter adipogenesis in rodents, yet whether the effects are restricted to 4-NP-exposed offspring only or can be transmitted to the next generation are not known. Pregnant Wistar rats received either vehicle or 4-NP (5, 25 and 125μg/kg/day) from gestation to postnatal day 21. F1 pups were subjected to blood biochemistry tests, or killed to obtain their gonadal fat to determine gene expression. Some F1 adult female rats were mated with F1 males from control group to obtain F2 pups, but without any exposure to 4-NP in the perinatal stage. F2 pups underwent studies similar to those performed on F1 pups. Serum total cholesterol, leptin levels were significantly elevated, the quantity and size of fat cells were increased, gene expression of key regulators of adipogenesis and lipogenic pathway of fat tissue were perturbed by 4-NP (p<0.05 or p<0.01). In addition, the expression of mRNA levels and protein of ERα were downregulated in adipose tissue in the two generation offspring. Perinatal exposure to 4-NP affects the adipogenesis in both male and female F1 offspring, and this effect can be progressed to the F2 offspring through the maternal line.

Reproductive status and sex show strong effects on knee OA in a baboon model

OBJECTIVE

We aimed to characterize severity and occurrence of knee osteoarthritis (OA), and effects of age, sex, body mass, and reproductive status on population-level normal variation in this condition in the baboon, a natural model of human knee OA.

METHODS

We visually inspected articular cartilage of distal right femora of 464 baboons (309 females, 155 males) and assigned an OA severity score (comparable to a modified Outerbridge score) from 1 = unaffected to 4 = advanced OA (eburnation). Presence/absence of osteophytes was recorded. We tested for significant effects of age, sex, body mass, and, in females, reproductive status (pre-, peri-, or post-menopausal) on OA. When appropriate, analyses were repeated on an age-matched subset (153 of each sex).

RESULTS

Knee OA was more frequent and severe in older animals (P < 0.0001), but significant age variation was apparent in each severity grade. Sex differences within the younger and older age groups suggest that males develop knee OA earlier, but females progress more quickly to advanced disease. There is a strong relationship between reproductive status and OA severity grade in females (P = 0.0005) with more severe OA in peri- and post-menopausal female baboons, as in humans.

CONCLUSIONS

Idiopathic knee OA is common in adult baboons. Occurrence and severity are influenced strongly by reproductive status in females, and by sex with regard to patterns of disease progression - providing an animal model to investigate sex-specific variation in OA susceptibility in which the environmental heterogeneity inherent in human populations is vastly reduced.

Body size and endometriosis: results from 20 years of follow-up within the Nurses' Health Study II prospective cohort

STUDY QUESTION

Is there a relationship between body mass index (BMI), body shape and endometriosis?

SUMMARY ANSWER

Endometriosis is inversely associated with early adult BMI and may correlate with a peripheral body fat distribution.

WHAT IS KNOWN ALREADY

The literature suggests an inverse relation between endometriosis and BMI, although few studies have specifically explored this association in depth.

STUDY DESIGN, SIZE, DURATION

Prospective cohort study using data collected from 116 430 female nurses from September 1989 to June 2011 as part of the Nurses' Health Study II cohort. PARTICIPANTS/MATERIALS, METHODS AND SETTING: Cases were restricted to laparoscopically confirmed endometriosis. Weight at age 18 and height were reported at baseline, and current weight was updated every 2 years. Waist and hip measurements were first taken in 1993 and updated in 2005. Rate ratios (RR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards models with time-varying covariates.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 5504 incident cases of endometriosis were reported during 1 299 349 woman-years (incidence rate = 385 per 100 000 woman-years). BMI at age 18 and current BMI were each significantly inversely associated with endometriosis (P-value, test for linear trend <0.0001). Both associations were stronger among infertile women. Obese infertile women with current BMIs of 35-39.9 kg/m(2) and ≥ 40 kg/m(2) had a 55% (95% CI 0.30-0.67) and a 62% (95% CI 0.23-0.62) lower risk of endometriosis, respectively, compared with the low-normal BMI referent (18.5-22.4 kg/m(2)). Rates of endometriosis were nearly 3-fold higher in women with waist-to-hip ratios <0.60 (RR = 2.78, 95% CI 1.38-5.60) compared with those with waist-to-hip ratios between 0.70 and 0.79, although the sample size for this category was very small.

LIMITATIONS AND REASONS FOR CAUTION

Although women with undiagnosed endometriosis certainly remain in the comparison population even in this prospective cohort study, the community prevalence of endometriosis in an asymptomatic population is very low. Moreover, the characteristics of this small proportion of undiagnosed cases are diluted among the >90 000 women accurately defined as being endometriosis-free and are, therefore, unlikely to impact on effect estimation. Although geographically diverse, the NHS II cohort is overwhelmingly Caucasian, which may limit generalizability to more ethnically diverse populations. WIDER IMPLICATIONS OF THE STUDY: The results of this study suggest that endometriosis is inversely associated with early adult BMI and may correlate with a peripheral body fat distribution.

Osteoarthritis, osteoporosis, and exercise

With the aging of the work force, occupational health nurses must prepare for encounters with clients who are challenged by osteoarthritis or osteoporosis. Clients should be encouraged to exercise safely to promote functioning at home and work. This article reviews recent literature on the benefits of exercise for workers with osteoarthritis, osteoporosis, or both.

Effect of neuromuscular electrical muscle stimulation on energy expenditure in healthy adults

Weight loss/weight control is a major concern in prevention of cardiovascular disease and the realm of health promotion. The primary aim of this study was to investigate the effect of neuromuscular electrical stimulation (NMES) at different intensities on energy expenditure (oxygen and calories) in healthy adults. The secondary aim was to develop a generalized linear regression (GEE) model to predict the increase of energy expenditure facilitated by NMES and identify factors (NMES stimulation intensity level, age, body mass index, weight, body fat percentage, waist/hip ratio, and gender) associated with this NMES-induced increase of energy expenditure. Forty sedentary healthy adults (18 males and 22 females) participated. NMES was given at the following stimulation intensities for 10 minutes each: sensory level (E1), motor threshold (E2), and maximal intensity comfortably tolerated (E3). Cardiopulmonary gas exchange was evaluated during rest, NMES, and recovery stage. The results revealed that NMES at E2 and E3 significantly increased energy expenditure and the energy expenditure at recovery stage was still significantly higher than baseline. The GEE model demonstrated that a linear dose-response relationship existed between the stimulation intensity and the increase of energy expenditure. No subject’s demographic or anthropometric characteristics tested were significantly associated with the increase of energy expenditure. This study suggested NMES may be used to serve as an additional intervention for weight loss programs. Future studies to develop electrical stimulators or stimulation electrodes to maximize the comfort of NMES are recommended.