Obesity and osteoarthritis of the hands in women

No association between impaired glucose metabolism and osteoarthritis

OBJECTIVE

To investigate the association between markers of glucose metabolism and hand and knee osteoarthritis (OA).

METHODS

This is a cross-sectional analysis of baseline measurements of the Netherlands Epidemiology of Obesity (NEO) study, a population-based prospective cohort study. Fasting glucose, insulin and glycated hemoglobulin A1c (HbA1c) concentrations were measured, Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) was calculated and clinical OA was defined following the American College of Rheumatology (ACR) criteria. After exclusion of participants on glucose-lowering drugs, odds ratios (ORs) with 95% confidence intervals (CIs) for either hand, knee or both hand and knee OA were calculated (no OA as reference), as a function of each marker of glucose metabolism, with logistic regression analyses. Models were adjusted for age, ethnicity, education, height, weight and total body fat, and stratified by sex.

RESULTS

In 6197 participants (age 45-65 years, 56% women, mean body mass index (BMI) 26 kg/m(2)), prevalences of hand OA, knee OA or both were 7%, 10% or 4%, respectively. In men, the adjusted OR (95%CI) for hand OA was 1.18 (1.01-1.39) per standard deviation (SD) increase in plasma glucose (0.85 mmol/L). There were no further associations of glucose, HbA1c, insulin and HOMA-IR with the different types of OA, neither in men nor in women.

CONCLUSION

An impaired glucose metabolism does not seem be related to OA. In men, an association was observed for fasting glucose concentrations and hand OA. Future studies should investigate the presence of sex differences in the pathogenesis of hand OA.

Associations between body composition measurements of obesity and radiographic osteoarthritis in older adults: Data from the Dong-gu Study

Background

We examined the effects of fat deposition on radiographic osteoarthritis (OA) to determine the role of obesity in the pathogenesis of radiographic OA.

Methods

Data were taken from the Dong-gu cohort, a cross-sectional study of 2,367 subjects. Baseline characteristics, waist circumference (WC), waist-to-hip ratio (WHR), fat mass, and fat percentage were collected, along with X-rays of the knees and hands. Total knee and hand radiographic OA scores were summed using a semi-quantitative grading system, and then stratified by gender using a multiple linear regression model.

Results

After adjusting for confounders, weight was the only factor significantly associated with knee radiographic OA, regardless of gender (all p < 0.01). Regarding the hand, fat percentage had the largest effect on radiographic OA in males (p = 0.008), while WHR was the most significant factor in females (p = 0.001). For the knee, fat mass was the most important factor for radiographic OA in males (p = 0.001), while in females, body mass index was the most important factor (p < 0.001). Among the variables, only fat percentage was significantly related to both hand and knee radiographic OA in both genders (all p < 0.01).

Conclusions

Regardless of gender, weight was significantly associated with knee radiographic OA. Otherwise, fat deposition correlated with hand and knee radiographic OA in both genders, while the distribution of fat tissue was significantly associated with hand and knee radiographic OA only in females.

Adiposity and hand osteoarthritis: the Netherlands Epidemiology of Obesity study

Introduction

Obesity, usually characterized by the body mass index (BMI), is a risk factor for hand osteoarthritis (OA). We investigated whether adipose tissue and abdominal fat distribution are associated with hand OA.

Methods

The Netherlands Epidemiology of Obesity (NEO) study is a population-based cohort aged 45 to 65 years, including 5315 participants (53% women, median BMI 29.9 kg/m²). Fat percentage and fat mass (FM) (kg) were estimated using bioelectrical impedance analysis. The waist-to-hip ratio (WHR) was calculated. In 1721 participants, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) (cm²) were assessed using abdominal MR imaging. Hand OA was defined according to the ACR criteria.

Odds ratios (OR) with 95% confidence intervals (CI) were calculated for the association of fat percentage, FM, WHR, VAT and SAT with hand OA using logistic regression analyses per standard deviation, stratified by sex and adjusted for age.

Results

Hand OA was present in 8% of men and 20% of women. Fat percentage was associated with hand OA in men (OR 1.34 (95% CI 1.11 to 1.61)) and women (OR 1.26 (1.05 to 1.51)), as was FM. WHR was associated with hand OA in men (OR 1.45 (1.13 to 1.85)), and to a lesser extent in women (OR 1.17 (1.00 to 1.36)). Subgroup analysis revealed that VAT was associated with hand OA in men (OR1.33 (1.01 to 1.75)). This association increased after additional adjustment for FM (OR 1.51 (1.13 to 2.03)).

Conclusions

Fat percentage, FM and WHR were associated with hand OA. VAT was associated with hand OA in men, suggesting involvement of visceral fat in hand OA.

Exercise and osteoarthritis: cause and effects

Osteoarthritis (OA) is a common chronic joint condition predominantly affecting the knee, hip, and hand joints. Exercise plays a role in the development and treatment of OA but most of the literature in this area relates to knee OA. While studies indicate that exercise and physical activity have a generally positive effect on healthy cartilage metrics, depending upon the type of the activity and its intensity, the risk of OA development does appear to be moderately increased with sporting participation. In particular, joint injury associated with sports participation may be largely responsible for this increased risk of OA with sport. Various repetitive occupational tasks are also linked to greater likelihood of OA development. There are a number of physical impairments associated with OA including pain, muscle weakness and altered muscle function, reduced proprioception and postural control, joint instability, restricted range of motion, and lower aerobic fitness. These can result directly from the OA pathological process and/or indirectly as a result of factors such as pain, effusion, and reduced activity levels. These impairments and their underlying physiology are often targeted by exercise interventions and evidence generally shows that many of these can be modified by specific exercise. There is currently little clinical trial evidence to show that exercise can alter mechanical load and structural disease progression in those with established OA, although a number of impairments, that are amenable to change with exercise, appears to be associated with increased mechanical load and/or disease progression in longitudinal studies.

High dietary fat and the development of osteoarthritis in a rabbit model

OBJECTIVE

Osteoarthritis (OA) is associated with obesity, although this relationship remains unclear. Proposed etiologies of OA in obesity include mechanical loading of malaligned joints and possible toxicity of dietary fat. The hypothesis tested in the present study was that increased dietary fat worsens OA in both malaligned and normal joints, detected by biochemical and histological cartilage markers.

METHOD

83 New Zealand white rabbits were divided among two conditions related to OA: bowing of the knee and a 14%kcal vs 47.8%kcal fat diet. Rabbit weights and knee angles were compared throughout the experiment. At 28 and 38 weeks, intra-articular forces were measured, animals sacrificed, and knee cartilage examined for histological changes, glycosaminoglycan content, 35S uptake, and aggrecanase-1 expression.

RESULTS

There were no differences in animal weights or intra-articular forces between the two diets. Despite increased fat content in their diet, animals on the 47.8%kcal fat diet did not gain excess weight. Representative histology showed atypical shearing of articular cartilage among animals on the high fat diet. Animals on the 47.8%kcal fat diet had suppression of protein synthesis compared to the 14%kcal fat diet: lower glycosaminoglycan content and aggrecanase-1 expression in all knee compartments at both times, and lower 35S uptake at 38 weeks.

CONCLUSION

These results suggest dietary fat, independent of animal weight, results in altered chondrocyte function. Increased dietary fat was associated with changes in rabbit cartilage in vivo and appears to be a risk factor for the development of OA.

Hand osteoarthritis in the Abkhazian population

The aim of the study was to evaluate the prevalence and pattern of radiographic hand osteoarthritis (OA) in an Abkhazian community-based sample and its association with age, sex, body mass index (BMI) and place of residence. The study sample was comprised of 542 males with a mean age of 43.9, sd 15.6 years and 463 females with a mean age of 44.9, sd 13.9 years. OA was evaluated for 14 joints of the left hand according to the Kellgren and Lawrence grading scheme. Statistical analyses included prevalence estimation, multiple regression analysis and chi(2) tests. In the entire Abkhazian sample the average prevalence of hand OA was 33.6% for males and 35.4% for females. After age 65, the prevalence of hand OA was 87.5% for males and 83.3% for females. No sex differences were found in the prevalence or number of affected hand joints. Statistically significant association was found between the number of affected joints and BMI, but not between the prevalence of hand OA and BMI. Different prevalences of radiographic hand OA were found in individuals from different villages, after adjustment for age, sex and BMI. Additional studies are needed to explore the possible reasons for such differences.

Prevalence, pattern and determinants of radiographic hand osteoarthritis in Turkmen community-based sample

The aim of the study was to evaluate the prevalence and pattern of radiographic hand osteoarthritis (OA) in Turkmen community-based sample and its association with age, sex, and BMI. The study population was comprised of Turkmens (277 males and 427 females, age 19-90 years). OA was evaluated for 14 joints of each hand according to the Kellgren and Lawrence grading scheme. Statistical analyses included prevalence estimation, linear and polynomial regressions, and chi2 tests. About 13.8% of individuals before age 36 had at least one joint with OA, and the prevalence reached 100% after age 65. For males and females the best-fitted and most parsimonious model of association between age and number of affected hand joints was a two interval linear one. After adjustment for age, we found that females with severe obesity have higher risk of development of hand OA than those with normal weight [OR(95%CI): 3.88 (1.20-12.60)].

Obesity and osteoarthritis in knee, hip and/or hand: an epidemiological study in the general population with 10 years follow-up

Background

Obesity is one of the most important risk factors for osteoarthritis (OA) in knee(s). However, the relationship between obesity and OA in hand(s) and hip(s) remains controversial and needs further investigation. The purpose of this study was to investigate the impact of obesity on incident osteoarthritis (OA) in hip, knee, and hand in a general population followed in 10 years.

Methods

A total of 1854 people aged 24–76 years in 1994 participated in a Norwegian study on musculoskeletal pain in both 1994 and 2004. Participants with OA or rheumatoid arthritis in 1994 and those above 74 years in 1994 were excluded, leaving n = 1675 for the analyses. The main outcome measure was OA diagnosis at follow-up based on self-report. Obesity was defined by a body mass index (BMI) of 30 and above.

Results

At 10-years follow-up the incidence rates were 5.8% (CI 4.3–7.3) for hip OA, 7.3% (CI 5.7–9.0) for knee OA, and 5.6% (CI 4.2–7.1) for hand OA. When adjusting for age, gender, work status and leisure time activities, a high BMI (> 30) was significantly associated with knee OA (OR 2.81; 95%CI 1.32–5.96), and a dose-response relationship was found for this association. Obesity was also significantly associated with hand OA (OR 2.59; 1.08–6.19), but not with hip OA (OR 1.11; 0.41–2.97). There was no statistically significant interaction effect between BMI and gender, age or any of the other confounding variables.

Conclusion

A high BMI was significantly associated with knee OA and hand OA, but not with hip OA.

Risk factors in familial osteoarthritis: the GARP sibling study

PURPOSE

To investigate the association between systemic and local risk factors and familial osteoarthritis (OA) at multiple sites.

METHODS

Patients and their siblings had primary OA at multiple sites at middle age. OA diagnosis followed the American College of Rheumatology criteria. We recruited 345 controls (mean age 57 years (range 40-76), 64% women) by random sampling from the population by telephone and collected all data by questionnaires. Odds ratios (ORs) were adjusted for sex, age and body mass index (BMI) (kg/m(2)), 95% confidence intervals (CIs95) were computed using robust standard errors with the intra-family effect taken into account.

RESULTS

Three hundred and eighty-two patients (mean age 60 years [range 43-79]), 82% women had OA in the spine (80%), hands (72%), knees (34%) and hips (24%). In women, an association of familial OA with a young age at natural menopause (<45 years), OR=2.6 (CI95 1.5-4.5) was found. Physically demanding jobs led to an increased risk of familial OA in men: OR=2.6 (CI95 1.3-5.3). Familial OA was more prevalent in individuals with a BMI>30, OR=2.0 (CI95 1.3-3.2) compared to a BMI of <25. Taller persons had a lower risk of familial OA, OR=0.33 (0.1-0.8) in the height category >180 cm relative to a height of <160 cm. A history of meniscectomy, increased the risk of familial OA at multiple sites with knee involvement, OR=6.2 (CI95 3.0-12.7).

CONCLUSIONS

Systemic and local risk factors play a role in the etiology of familial OA at multiple sites.

The impact of obesity on the musculoskeletal system

Obesity is associated with a range of disabling musculoskeletal conditions in adults. As the prevalence of obesity increases, the societal burden of these chronic musculoskeletal conditions, in terms of disability, health-related quality of life, and health-care costs, also increases. Research exploring the nature and strength of the associations between obesity and musculoskeletal conditions is accumulating, providing a better understanding of underlying mechanisms. Weight reduction is important in ameliorating some of the manifestations of musculoskeletal disease and improving function.

Morbidity and mortality risk associated with an overweight BMI in older men and women

BACKGROUND

There is controversy as to whether older adults with a BMI in the overweight range (25 to 29.9 kg/m2) are at increased health risk and whether they should be encouraged to lose weight. The purpose of this study was to determine whether older adults with a BMI in the overweight range are at increased morbidity and mortality risk.

METHODS

Participants consisted of 4968 older (>or=65 years) men and women from the Cardiovascular Health Study limited access dataset. Based on BMI (kg/m2), participants were grouped into normal-weight (20 to 24.9 kg/m2), overweight (25 to 29.9 kg/m2), and obese (>or=30 kg/m2) categories. Participants were followed for up to 9 years to determine if they developed 10 weight-related health outcomes that are pertinent to older adults. Cox proportional hazards models were used to estimate the hazards ratios of morbidity and mortality after adjusting for age, sex, income, smoking, and physical activity.

RESULTS

Compared with the normal-weight group, the risks of myocardial infarction, stroke, sleep apnea, urinary incontinence, cancer, and osteoporosis were not different in the overweight group (p>0.05). The risks for arthritis and physical disability were modestly increased in the overweight group (p<0.05), whereas the risk for type 2 diabetes was increased by 78% in the overweight group (p<0.01). After adjusting for all relevant covariates, all-cause mortality risk was 11% lower in the overweight group (p<0.05).

CONCLUSIONS

A BMI in the overweight range was associated with some modest disease risks but a slightly lower overall mortality rate. These findings suggest that a BMI cut-off point of 25 kg/m2 may be overly restrictive for the elderly.

[Abdominal obesity and knee ostheoarthritis]

The objective of our study was to determine whether waist circumference (WC) is a more reliable indicator than body mass index (BMI) of the presence of knee osteoarthritis in obese subjects.

PATIENTS AND METHODS

We performed an observational study of obese patients with no other risk factors for knee osteoarthritis. For each patient, we evaluated BMI, WC, duration of obesity and knee pain. Two groups were identified: "asymptomatic patients" (AG), without knee pain, and "symptomatic patients" (SG). For the SG, we measured pain intensity (visual analog scale [VAS], 0-100 mm) and functional repercussions (using the Lequesne and WOMAC indexes). Patients with knee pain underwent standard radiographic procedures to search for signs of osteoarthritis, and the SG was divided into two subgroups: with radiological signs of osteoarthritis (SG-1) and without radiological signs of osteoarthritis (SG-2). The AG and SG groups and SG-1 and SG-2 groups were compared for age, sex, and duration of obesity. Comparisons of BMI, WC, and function involved the Student's t-test.

RESULTS

We recruited 56 patients for the study (82.5% females; mean obesity duration (13+/-6.5 years; mean age 43.21+/-9.58 years). The mean BMI was 39.6+/-7.23 kg/m(2) and mean WC was 113+/-14.3 cm. We found 33 patients (59%) with knee pain. Independent of age, sex, duration of obesity and BMI, the SG showed more significant WC (117.27+/-14.71 cm vs. 107+/-11.75 cm for the AG, P 0.01). In the same group and independent of the already mentioned factors, the patients with radiological signs of osteoarthritis showed significant WC [122+/-15.57 cm (SG-1) vs. 108+/-6.88 cm (SG-2) (P 0.01)]. Moreover, the VAS score of pain at rest and during effort and the WOMAC and Lequesne scores were 16+/-25.7 mm, 75+/-18.3 mm, 12.3+/-8.92 and 11.5+/-5.44 (SG-1) and 7+/-18.4 mm, 70+/-19.2 mm, 5.7+/-3.05, and 6.9+/-3.79 (SG-2), respectively. The difference between SG-1 and SG-2 was significant only for the WOMAC (P=0.015) and Lequesne (P=0.026) scores.

CONCLUSION

Independent of BMI, WC appears to be a factor associated with the presence of knee pain and osteoarthritis in obese patients. Furthermore, a high WC is associated with significant functional repercussion.

Do metabolic factors add to the effect of overweight on hand osteoarthritis? The Rotterdam Study

BACKGROUND

As hand joints are non-weight bearing, the association between overweight and hand osteoarthritis (HOA) is critical to understanding how overweight may associate with osteoarthritis (OA) apart from axial load. Overweight might be associated with the occurrence of OA through other metabolic factors.

AIM

To evaluate the role of overweight in HOA, cross-sectional data of a population-based study were used (> or =55 years, n = 3585). The role of diabetes, hypertension and total cholesterol:high-density lipoprotein (HDL)-cholesterol ratio on HOA, and whether they play an intermediate role in the association of overweight/HOA was investigated. Furthermore, the prevalence of HOA in the concurrent presence of overweight and other metabolic factors was evaluated.

RESULTS

Independently of other metabolic factors, overweight (body mass index (BMI) >27.4 kg/m(2)) showed a significant association with HOA (OR 1.4, 95% CI 1.2 to 1.7). The association between diabetes and HOA was only present in people aged 55-62 years (OR 1.9, 95% CI 1.0 to 3.8), but was absent in the total population or in other age groups. The association of hypertension with HOA was weak, and disappeared after adjustment for BMI. The total/HDL cholesterol ratio showed no significant association with HOA. The concurrent presence of overweight, diabetes and hypertension resulted in an even higher prevalence of HOA (OR 2.3, 95% CI 1.3 to 3.9) compared with subjects with none of these characteristics; this prevalence increased further in the younger age group (OR 3.2, 95% CI 1.1 to 8.8).

CONCLUSION

No intermediate effect of metabolic factors on the association of overweight with HOA was found. An increase in the prevalence of HOA, however, seems to be present when overweight occurs together with hypertension and diabetes especially at a relatively young age.

Separate and combined influence of body mass index and waist circumference on arthritis and knee osteoarthritis

OBJECTIVE

To determine if the combination of body mass index (BMI) and waist circumference (WC) explains an additional component of arthritis and knee osteoarthritis risk than is accounted for by either anthropometric measure alone.

DESIGN

Cross-sectional study.

PARTICIPANTS

Participants were part of the Third National Health and Nutrition Examination Survey, a representative sample of Americans conducted from 1988 to 1994. The arthritis analyses included 15 570 participants aged 18 years and older. The knee osteoarthritis analyses included 2323 participants aged 60 years and older. Body mass index and WC were measured in all participants and classified into sex-specific tertiles.

OUTCOME MEASURES

Arthritis (determined by self-report) and knee osteoarthritis (determined by radiograph).

RESULTS

Independent of sex, the likelihood of arthritis and knee osteoarthritis increased in a graded fashion when moving from the lowest to highest BMI tertile and when moving from the lowest to highest WC tertile (Ptrend < 0.01). In the next phase of analyses, subjects were divided into WC tertiles within each of the BMI tertiles. Within the lowest BMI tertile, the likelihood of arthritis and knee osteoarthritis was not different in the lowest, middle and highest WC tertiles (P > 0.1). Within the middle BMI tertile, the middle and high WC tertiles were more likely to have knee osteoarthritis compared to the lowest WC tertile (P < 0.05). Within the highest BMI tertile, the highest WC tertile was more likely to have arthritis and knee osteoarthritis compared to the lowest WC tertile (P < 0.05).

CONCLUSIONS

Both BMI and WC were strong predictors of arthritis and knee osteoarthritis. When a categorical approach was used for BMI and WC, similar to that in the clinical setting, independent effects of these anthropometric variables were observed.

Osteoarthritis of finger joints in Finns aged 30 or over: prevalence, determinants, and association with mortality

BACKGROUND

Prevalence and risk factors of osteoarthritis (OA) in finger joints have been amply explored in previous studies. However, no study has focused on finger joint OA as a predictor of mortality.

OBJECTIVE

To investigate finger joint OA for its associations with alleged risk factors and with life expectancy in an extensive health survey.

METHODS

From 1978 to 1980 a representative population sample of 8000 Finns aged 30 years or over was invited to participate in a comprehensive health examination; 90% accepted. Hand radiographs were taken from 3595 subjects. By the end of 1994, 897 of these had died.

RESULTS

The prevalence of OA of Kellgren's grade 2 to 4 in any finger joint and in at least two symmetrical pairs of distal interphalangeal joints (DIPs) was 44.8% and 16.0%, respectively. Age and body mass index were significant determinants for OA both in any finger joint and in symmetrical DIP OA. The history of physical workload in women showed a positive association with OA in any finger joint. Smoking in men seemed to protect against symmetrical DIP OA. As adjusted for the determinants above, symmetrical DIP OA predicted mortality in women (relative risk (RR), 1.23; 95% confidence interval (95% CI) 1.01 to 1.51), but not in men (RR 0.89; 95% CI 0.68 to 1.16). In men, however, OA in any finger joint significantly predicted cardiovascular deaths (RR 1.42; 95% CI 1.05 to 1.92).

CONCLUSION

OA in any finger joint and symmetrical DIP OA have different risk factor profiles and predict mortality in different patterns between men and women.

Epidemiology and genetics of hand osteoarthritis

The aim of this session was to identify current issues and problems relating to risk factors for hand osteoarthritis (OA). The following important factors were discussed: Genetics, Age, Gender, Obesity, HRT (hormone replacement therapy), Physical activity/trauma.

The patterns and prevalence of hand osteoarthritis in a population of disabled older women: The Women's Health and Aging Study

OBJECTIVE

To describe the prevalence of hand osteoarthritis (OA) by joint site, joint count and severity in a representative population of older disabled women.

METHODS

1,002 moderately to severely disabled women aged > or = 65 years were selected from a representative population of community-dwelling women. Hand OA was established using a reproducible algorithm based on self-reported pain, standardized physical examinations, hand photographs, and physician questionnaire responses. OA was categorized as either symptomatic disease, intermittently symptomatic/ asymptomatic disease, possible disease, or no disease.

RESULTS

Symptomatic OA, requiring the presence of hand pain on most days for at least 1 month, occurred in approximately 23% of disabled older women in each age group, and most reported pain in the moderate to severe range. The prevalence of intermittently symptomatic/ asymptomatic OA was higher with increasing age. Finally, the most commonly affected hand OA sites were the distal interphalangeal (DIP) and the first carpometacarpal (CMC1) joint groups.

CONCLUSION

These findings demonstrate the very high prevalence of clinical hand OA in disabled older women and show that a large proportion of hand OA results in substantial symptoms.

Grip strength and the risk of developing radiographic hand osteoarthritis: results from the Framingham Study

OBJECTIVE

In knees, quadriceps strength may protect against osteoarthritis (OA). Muscle activity is a major determinant of forces at the hand joints, and grip is a common task during which high muscle forces are sustained, especially at the proximal hand joints (metacarpophalangeal [MCP] joints and thumb base). This longitudinal study of radiographic hand OA examined the association between incident OA at different hand joints and maximal grip strength.

METHODS

Four hand joint groups were studied: distal interphalangeal (DIP), proximal interphalangeal (PIP), MCP, and the base of the thumb (carpometacarpal and scaphotrapezial combined). Subjects were members of the Framingham OA Study who had a baseline radiograph in 1967-1969 and a followup radiograph in 1992-1993 (mean followup 24 years) and had no prevalent radiographic OA in any hand joint at baseline. Incident disease was defined as development of OA defined as a modified Kellgren/Lawrence grade of > or =2. Grip strength was measured in kilograms by dynamometer in 1958-1961 and again in 1960-1963, and the 2 measures were averaged and divided into sex-specific tertiles. Joint-based analysis was performed by adjusting for age, physical activity, and occupational category using the lowest grip strength tertile as the referent.

RESULTS

Baseline and followup radiographs were obtained from 746 subjects. Of these, 453 subjects with no prevalent OA at baseline were eligible for analysis. In men, higher maximal grip strength was associated with an increased risk of OA in the PIP (highest tertile odds ratio [OR] 2.8 compared with lowest tertile, 95% confidence interval [95% CI] 1.2-6.7), MCP (highest tertile OR 2.9, 95% CI 1.1-7.4), and thumb base joints (highest tertile OR 2.8, 95% CI 1.1-7.4). In women, there was increased risk of OA in the MCP joints (highest tertile OR 2.7, 95% CI 1.1-6.4).

CONCLUSION

Men with high maximal grip strength are at increased risk for the development of OA in the PIP, MCP, and thumb base joints, and women, in the MCP joints. No association was found between maximal grip strength and incident OA in the DIP joints of men or women.

Chondrocyte apoptosis increases with age in the articular cartilage of adult animals

BACKGROUND

Apoptosis in vivo has been identified in developing cartilage from embryonic chick sterna and avian and murine growth plates. To date, no evidence exists that chondrocytes in articular cartilage undergo apoptosis.

METHODS

We examined the distribution of cells demonstrating fragmented DNA in the articular knee cartilage of C57BL/6 mice (aged 11, 18, 24, and 30 months) and Wistar rats (aged 6, 12, and 24 months) using a DNA end-labeling technique.

RESULTS

Control experiments utilizing retinoic acid-induced apoptosis in a chondrocyte cell line, established that DNA end-labeling correlated with DNA ladder formation. In vivo, apoptotic cells were detected in articular cartilage tissue in both species examined. The percentage of apoptotic cells increased significantly (P < 0.05 with age) for all joint surfaces in both species. No significant difference was found between the medial and lateral or femoral and tibial joint surfaces of the knee. Apoptotic cells were observed in both the calcified and uncalcified regions of the articular cartilage of C57 mice. In the rat, only the calcified region of articular cartilage contained apoptotic cells.

CONCLUSIONS

These results suggest that apoptosis plays a role in some aspect of maintenance, remodeling, or turnover of mature articular cartilage. In addition, the increase in apoptosis associated with aging could contribute to the greater risk for cartilage degeneration.

Understanding the relationship between body weight and osteoarthritis

Overweight people are at high risk of developing knee osteoarthritis (OA) and may also be at increased risk of hand and hip OA. Furthermore, being overweight accelerates disease progression in knee OA. While the increased joint stress accompanying obesity may explain the strong linkage between obesity and knee OA risk, it does not necessarily explain why obese people have a high risk of disease in the hand nor why obese women are at higher comparative risk of knee disease than obese men. Unfortunately, studies of metabolic factors linked to obesity have not provided an explanation for these findings. There are a paucity of data on weight loss as a treatment for OA, but preliminary information suggests it is especially effective in knee disease and that even small amounts of weight reduction may have favourable effects.