Factors that may mediate the relationship between physical activity and the risk for developing knee osteoarthritis

Asymmetric Post-Traumatic Knee Arthritis Is Closely Correlated With Both Severity and Time for Lower Limb Coronal Plane Malalignment

OBJECTIVE

Mechanical alignment of the lower limbs has been suggested to cause abnormal uneven loading across the compartments at the knee, but its contribution to the initiation and progression of arthritis remains controversial. This study aimed to establish whether malalignment of the lower limb after trauma is associated with worsened arthritis scores in the theoretically overloaded compartment, and if arthritis scores continuously correlate with the degree of malalignment and time with deformity.

DESIGN

After screening 1160 X-rays, 60 patients were identified with long-leg radiographs > 2 years after fracture. Measurement of mechanical axis deviation (MAD) divided into groups of varus malalignment (n = 16, >16 mm), valgus (n = 25, <0 mm), and normal alignment (n = 19). Alignment and bilateral knee compartmental arthritis scores were recorded by three clinicians, compared via analysis of variance and assessed with linear regression against time since injury using MAD as a covariate.

RESULTS

In varus and valgus malalignment, there was a greater mean arthritis score in the "overloaded" compartment compared to the contralateral side, with varus medial Osteoarthritis Research Society International (OARSI) scores 5.17 ± 2.91 vs 3.50 ± 2.72 (P = 0.006) and Kellegren-Lawrence scores 2.65 ± 1.19 vs 1.79 ± 1.24 (P ≤ 0.001). In a linear regression model, OARSI arthritis score was significantly associated with absolute MAD (0.6/10 mm MAD, P < 0.001) and time (0.7/decade, P ≤ 0.001).

CONCLUSIONS

Malalignment consistently results in more advanced arthritis scores in the overloaded compartment, most likely related to abnormal loading across the knee. Severity of arthritis using OARSI grading continuously correlates with degree of malalignment and time with deformity after post-traumatic malunion.

The Influence of Athletes' Age in the Onset of Osteoarthritis: A Systematic Review

PURPOSE

Whether sport participation is a risk factor for osteoarthritis (OA) development or progression is controversial. Mechanical overload, injuries, genetics, and acquired disorders concur to the onset of OA, with high variability between sports and participants. This study investigated the association between participation in specific sports and the risk of developing knee and hip OA in athletes at different ages. We hypothesized that young athletes who are exposed to high levels of physical activities have a greater risk of developing OA.

MATERIALS AND METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Google scholar, EMABSE, and Web of Science were accessed in October 2021. No time constrains were used for the search. All the published clinical studies reporting data about relationship between physical activity, OA, and age were included.

RESULTS

The Newcastle-Ottawa Scale resulted in a final score ≥7 for all studies, attesting good quality of the methodological assessment. Data from 27,364 patients were retrieved. The mean age was 48.2±16.7 years. In all, 21.8% were women.

CONCLUSIONS

Our systematic review suggests an association between high levels of physical activities and knee and hip OA in men younger than 50 years. People who practice intense physical activity, such as professional athletes or heavy workers, are more prone to develop early-onset OA.

Intensive Physical Activity Increases the Risk of Knee and Hip Arthroplasty: A Systematic Review

PURPOSE

The present study investigated the type of sport and activity level of athletes before they underwent knee and/or hip arthroplasty for osteoarthritis (OA), and compared them with a control group of subjects who did not undergo knee and hip arthroplasty. We hypothesed athletes exposed to high physical loads during sports had the highest risk of developing OA requiring arthroplasty.

MATERIALS AND METHODS

This systematic review was conducted according to the PRISMA guidelines. All the comparative clinical trials to August 2021 investigating the sport activity level between subjects who underwent arthroplasty versus those who did not undergo arthroplasty for OA were considered.

RESULTS

Data from 5 studies and 3638 patients were collected. The mean age for both groups was 47.61±15.5 years, and the mean body mass index was 24.6±2.1 kg/m2 17.6% were women. The Newcastle-Ottawa scale attested good quality of the methodology of the investigations included in the present study.

CONCLUSION

Intense physical exercise, implying a high cumulative number of hours of exercise which can lead to excessive joint overload, in both sexes is associated with greater likelihood of early knee and hip OA which may lead to prosthetic surgery. Moderate and recreational exposure to sport has minor degenerative effects, and is not associated with early onset OA requiring arthroplasty.

The Degradation of Synthetic Polymeric Scaffolds With Strut-like Architecture Influences the Mechanics-dependent Repair Process of an Osteochondral Defect in Silico

Current clinical treatments of osteochondral defects in articulating joints are frequently not successful in restoring articular surfaces. Novel scaffold-based tissue engineering strategies may help to improve current treatment options and foster a true regeneration of articulating structures. A frequently desired property of scaffolds is their ability to degrade over time and allow a full restoration of tissue and function. However, it remains largely unknown how scaffold degradation influences the mechanical stability of the tissue in a defect region and, in turn, the regenerative process. Such differing goals–supporting regeneration by degrading its own structure–can hardly be analyzed for tissue engineered constructs in clinical trials and in vivo preclinical experiments. Using an in silico analysis, we investigated the degradation-induced modifications in material and architectural properties of a scaffold with strut-like architecture over the healing course and their influence on the mechanics-dependent tissue formation in osteochondral defects. The repair outcome greatly varied depending on the degradation modality, i.e. surface erosion or bulk degradation with and without autocatalysis, and of the degradation speed, i.e. faster, equal or slower than the expected repair time. Bulk degradation with autocatalysis, independently of degradation speed, caused the mechanical failure of the scaffold prior to osteochondral defect repair and was thereby deemed inappropriate for further application. On the other hand, scaffolds with strut-like architecture degrading by both surface erosion and bulk degradation with slow degradation speed resulted in comparably good repair outcomes, thereby indicating such degradation modalities as favorable for the application in osteochondral defects.

[Possibilities and limits of conservative treatment for osteoarthritis : Sport advice, training therapy, orthotics and cartilage therapeutics]

Hintergrund

Arthrose – die Degeneration von Gelenken – ist ein weit verbreitetes Problem durch alle Bevölkerungsschichten, das im zunehmenden Alter vermehrt auftritt und die häufigste Ursache für mobilitätseinschränkende Schmerzen am Bewegungsapparat ist. Etwa 70–80 % der über 70-Jährigen zeigen Zeichen einer Gelenksdegeneration. Insgesamt sind bis zu 25 % der Gesamtbevölkerung davon betroffen, aufgrund der generellen Alterung der Bevölkerung mit steigender Tendenz. Die Inzidenz der Arthrose steigt aber schon ab dem 40 Lebensjahr, wobei besonders posttraumatische und sekundäre Arthroseformen zum Tragen kommen.

Anspruch

Der Wunsch nach hoher Mobilität und Sport zieht sich als Phänomen ebenfalls durch alle Altersgruppe. Dies ist mit hohen Gelenkbelastungen verbunden und stellt damit eine große Herausforderung an vor allem früh degenerativ veränderte Gelenksstrukturen dar. In diesem Zusammenhang ist der orthopädisch tätige Arzt gefordert, die Belastbarkeit von geschädigten Gelenken abzuschätzen und so früh wie möglich präventive Schritte sowie gegebenenfalls konservative Therapien einzuleiten, um die Progression der Arthrose zu verhindern und damit den eventuell notwendigen Gelenkersatz möglichst weit nach hinten zu schieben.

An exploratory study to investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in adult males

Purpose

To investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in a cross-sectional sample of adult males. This study utilizes several emerging biomarkers that have been associated with early joint degenerative changes; serum COMP (cartilage oligomeric matrix protein), HA (hyaluronan) and lubricin.

Methods

Eighty-one males (age: mean (range): 43(18–70) years; body mass index: 25.2 (21.0–30.6) kg/m²) volunteered. Resting serum COMP, HA and lubricin concentrations were determined via commercially available enzyme-linked immunosorbent assay (ELISA) and femoral trochlear cartilage thickness via supra-patellar ultrasound imaging. Physical activity levels were assessed using questionnaires. Statistical analyses were performed using correlation and regression analyses.

Results

Age was correlated with lateral trochlear cartilage thickness (r = − 0.372; p < 0.01) and serum COMP (r = 0.342; p < 0.01). 7-day physical activity was correlated with serum COMP (r = 0.357, p < 0.01), and 12-month physical activity with both lateral trochlear cartilage thickness (r = 0.340, p = 0.01) and serum HA (r = 0.296, p < 0.05). Regression analyses revealed that age significantly accounted for the variability in lateral cartilage thickness and serum COMP, following the adjustment for potential cofounders. However, the association between age and lateral trochlear cartilage thickness was not moderated by physical activity levels (all p > 0.05).

Conclusion

This study indicates that older age may be associated with thinner lateral trochlear cartilage and higher cartilage turnover. Being physically active may also be positive for lateral trochlear cartilage thickness. However, overall, both age and physical activity level only account for a small amount of the variability in cartilage thickness and serum biomarkers.

Characterization of individuals with osteoarthritis in the United States and their use of prescription and over-the-counter supplements

PURPOSE

Osteoarthritis (OA) is a frequently occurring, chronic condition; however, few studies describe the clinical characteristics of individuals with OA and the treatments they use to manage their symptoms. We conducted a study to characterize the OA population in the US and describe the nonsurgical management used by this population based on consumer research data collected through an online survey.

METHODS

Data from the 2017 US National Health and Wellness Survey (NHWS) for adults aged ≥35 years were used to evaluate the relationship between OA and certain study participant characteristics and to identify the most commonly used treatment options. NHWS data were collected through a survey of individuals drawn from the internet panel maintained by Lightspeed Research (Bridgewater, New Jersey) and its panel partners. Weighted estimates were generated using data from the 2016 Current Population Survey (Annual Demographics File) of the US Census Bureau. Comparisons between the general and OA populations were made based on body mass index (BMI), exercise frequency, and comorbid diagnoses of hypertension or diabetes. Among the OA population, the use of dietary supplements, prescription or over-the-counter (OTC) treatments with chondroitin with or without glucosamine (Ch ± Gl), prescription treatment by time since OA diagnosis, and utilization of a physical therapist were also recorded.

RESULTS

The prevalence of OA in the overall population was 17.6 % and was higher for individuals with a BMI ≥ 25 (21.9 %), patients diagnosed with hypertension or diabetes (36.2 %), and those who did not exercise regularly (19.0 %). Adults without OA were more likely to exercise regularly (12 days per month or more) than adults diagnosed with OA. Ch ± Gl (6.0 %) was the most commonly used OTC dietary supplement in the OA population, followed by omega-3 fatty acids (2.8 %), vitamin D (1.9 %), calcium (1.1 %), and multivitamins (0.7 %). Individuals using Ch ± Gl were more likely to use OTC only products (75.4 % vs 37.3 %) or prescription medications, namely non-steroidal anti-inflammatory drugs (NSAIDs) and/or opioids, and OTC products (24.6 % vs 13.0 %) compared with individuals not using Ch ± Gl, while individuals not using Ch ± Gl were more likely to be untreated (30.3 % vs 0) or to use prescription medications only (19.4 % vs 0). Nearly 32 % of individuals with OA reported using prescription treatments, and the likelihood of using a prescription treatment increased with number of years since OA diagnosis (<3 years: 27.5 %; ≥21 years: 32.5 %). The pharmaceutical products used by this population primarily consisted of nonsteroidal anti-inflammatory drugs, acetaminophen and opioids. Approximately 13 % of patients with OA had visited a physical therapist in the past 6 months.

CONCLUSIONS

The prevalence of OA was higher in those with a high BMI, and comorbid diabetes or hypertension. Individuals with OA using Ch ± Gl primarily reported use of OTC products only or used them in combination with prescription products. The likelihood of using prescription products increased with the length of OA history. These data provide valuable new information about demographics, clinical characteristics, and commonly used prescription and OTC treatments and dietary supplements in the OA population.

Self-Reported Knee Pain Does Not Impact Physical Training Negatively in Conscripts

INTRODUCTION

Despite the great number of investigations on the effects of injuries during military service, there is limited information available on the use of self-reported instruments. This study evaluated self-reported knee pain (KP) and its effect on physical performance during military service in the Estonian Defense Forces.

MATERIAL AND METHODS

Ninety-five male conscripts aged 19-25 years were divided into two study groups based on the occurrence of KP or not. Self-reported KP and function according to the Knee Injury and Osteoarthritis Outcome Score (KOOS) were measured. Physical fitness level was scored using the Army Physical Fitness Test (APFT). KOOS and APFT were measured in the beginning and at the end of the 6-month period of military service.

RESULTS

Significant differences in favor of the group without KP (P < 0.001) were found for all subgroups of the KOOS. In spite of KP, the physical condition improved significantly (P < 0.001) in both study groups as measured with both the APFT test (22.2% increase) and running time (10.3% decrease).

CONCLUSION

In conclusion, self-reported KP and limited function according to KOOS did not hinder the improvement of physical condition and running speed as assessed by APFT in Estonian conscripts.

WEIRD bodies: mismatch, medicine and missing diversity

Despite recent rapid advances in medical knowledge that have improved survival, conventional medical science's understanding of human health and disease relies heavily on people of European descent living in contemporary urban industrialized environments. Given that modern conditions in high-income countries differ widely in terms of lifestyle and exposures compared to those experienced by billions of people and all our ancestors over several hundred thousand years, this narrow approach to the human body and health is very limiting. We argue that preventing and treating chronic diseases of aging and other mismatch diseases will require both expanding study design to sample diverse populations and contexts, and fully incorporating evolutionary perspectives. In this paper, we first assess the extent of biased representation of industrialized populations in high profile, international biomedical journals, then compare patterns of morbidity and health across world regions. We also compare demographic rates and the force of selection between subsistence and industrialized populations to reflect on the changes in how selection operates on fertility and survivorship across the lifespan. We argue that, contrary to simplistic misguided solutions like the PaleoDiet, the hypothesis of evolutionary mismatch needs critical consideration of population history, evolutionary biology and evolved reaction norms to prevent and treat diseases. We highlight the critical value of broader sampling by considering the effects of three key exposures that have radically changed over the past century in many parts of the world-pathogen burden, reproductive effort and physical activity-on autoimmune, cardiometabolic and other mismatch diseases.

The different influence of high levels of physical activity on the incidence of knee OA in overweight and obese men and women-a gender specific analysis

OBJECTIVE

To investigate the influence of physical activity on incidence of knee osteoarthritis (OA) in overweight and obese men and women.

DESIGN

Data were extracted from the Osteoarthritis Initiative cohort on 1,667 participants without symptomatic knee OA at baseline. We used logistic regression and marginal effect models to estimate the effect of body mass index (BMI) and reported physical activity score, together with the interaction between them, on the development of radiographic knee OA, symptomatic knee OA and joint space narrowing (JSN) after 96-months.

RESULTS

Men in the most active quartile had almost double the likelihood of knee OA, independent of OA definition [e.g., odds ratio (OR) 2.4 (95%CI: 1.2-4.5) for radiographic knee OA]. Interaction analyses showed statistically significant interactions between physical activity and BMI on developing knee OA (i) radiographic OA _interaction(P = 0.039), (ii) symptomatic OA _interaction(P = 0.022), (iii) JSN _interactionP = 0.012). The margin plots in men also demonstrated that the effect of physical activity on different measures of knee OA were modified by high levels of BMI. These effects were not mirrored in women where at all BMI levels, the level of reported physical activity did not influence likelihood of knee OA independent of OA definition.

CONCLUSIONS

In overweight and obese men, there appears to be a threshold above which increasing levels of physical activity are associated with higher risk of knee OA. This is absent in women.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

The association between ambulatory activity, body composition and hip or knee joint replacement due to osteoarthritis: a prospective cohort study

OBJECTIVE

To examine the association between ambulatory activity (AA), body composition measures and hip or knee joint replacement (JR) due to osteoarthritis.

DESIGN

At baseline, 1082 community-dwelling older-adults aged 50-80 years were studied. AA was measured objectively using pedometer and body composition by dual-energy X-ray absorptiometry. The incidence of primary (first-time) JR was determined by data linkage to the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Log binomial regression with generalized estimating equations were used to estimate the risk of JR associated with baseline AA and body composition measures, adjusting for age, sex, X-ray disease severity, and pain.

RESULTS

Over 13 years of follow-up, 74 (6.8%) participants had a knee replacement (KR) and 50 (4.7%) a hip replacement (HR). AA was associated with a higher risk of KR (RR 1.09/1000 steps/day, 95% CI 1.01, 1.16) and a lower risk of HR (RR 0.90/1000 steps/day, 95% CI 0.81, 0.99). Body mass index (BMI) (RR 1.07/kg/m², 95% CI 1.03, 1.12), total fat mass (RR 1.03/kg, 95% CI 1.01, 1.06), trunk fat mass (RR 1.05/kg, 95% CI 1.00, 1.09), and waist circumference (RR 1.02/cm, 95% CI 1.00, 1.04) were associated with a higher risk of KR. Body composition measures were not associated with HR.

CONCLUSIONS

An objective measure of AA was associated with a small increased risk of KR and a small reduced risk of HR. Worse body composition profiles were associated with KR, but not HR. Altogether this may suggest different causal pathways for each site with regard to habitual activity and obesity.

Dose-response relationship between sports activity and musculoskeletal pain in adolescents

Supplemental Digital Content is Available in the Text.

A school-based cohort study showed that time spent in sports activity had a linear association with musculoskeletal pain prevalence and risk among Japanese adolescents.

Physical activity has multiple health benefits but may also increase the risk of developing musculoskeletal pain (MSP). However, the relationship between physical activity and MSP has not been well characterized. This study examined the dose–response relationship between sports activity and MSP among adolescents. Two school-based serial surveys were conducted 1 year apart in adolescents aged 12 to 18 years in Unnan, Japan. Self-administered questionnaires were completed by 2403 students. Associations between time spent in organized sports activity and MSP were analyzed cross-sectionally (n = 2403) and longitudinally (n = 374, students free of pain and in seventh or 10th grade at baseline) with repeated-measures Poisson regression and restricted cubic splines, with adjustment for potential confounders. The prevalence of overall pain, defined as having pain recently at least several times a week in at least one part of the body, was 27.4%. In the cross-sectional analysis, sports activity was significantly associated with pain prevalence. Each additional 1 h/wk of sports activity was associated with a 3% higher probability of having pain (prevalence ratio = 1.03, 95% confidence interval = 1.02-1.04). Similar trends were found across causes (traumatic and nontraumatic pain) and anatomic locations (upper limbs, lower back, and lower limbs). In longitudinal analysis, the risk ratio for developing pain at 1-year follow-up per 1 h/wk increase in baseline sports activity was 1.03 (95% confidence interval = 1.02-1.05). Spline models indicated a linear association (P < 0.001) but not a nonlinear association (P ≥ 0.45). The more the adolescents played sports, the more likely they were to have and develop pain.

Development and Prevention of Running-Related Osteoarthritis

Studies investigating the effect of running on risk for developing osteoarthritis at weight-bearing joints have reported with conflicting results. Generally, moderate-level running is not likely detrimental to joint health. However, many factors may be associated with the increased risk of developing osteoarthritis in runners. Factors often implicated in the development of osteoarthritis comprise those that increase joint vulnerability and those which increase joint loading. It is therefore suggested that running has different effects on different people. Efforts should be made to identify those with joint vulnerability and joint loading, and measures should be taken to have those factors and/or their running programs modified to run safely. Further investigations are needed to examine the effect of running on joint health under different conditions to confirm the association between exposure to risk factors and development of osteoarthritis, as well as to validate the effectiveness of measures for preventing running-related osteoarthritis.

Self-Reported Knee Symptoms Assessed by KOOS Questionnaire in Downhill Runners (Skyrunners)

BACKGROUND

The knee is the weight-bearing joint most commonly associated with sports injuries, and therefore is most at risk of developing degenerative changes, including osteoarthritis. Skyrunners can be considered to be at risk of developing symptoms of post-traumatic osteoarthritis due to downhill running.

AIM

The aim of this study was to analyze the health of the knee joints of a large group of these athletes via a specific self-report questionnaire.

METHODS

This study was carried out by asking the participants of seven official Skyraces (22.4±3.1 km length; 1596±393 m elevation) to fill out a questionnaire. Information regarding age, sex, downhill elevation (m) during training and competitions over the last month, and history of previous knee injury was also collected before the participants filled out the Knee injury and Osteoarthritis Outcome Score (KOOS), which is a reliable and validated instrument designed to assess patients' opinions about their knees and associated problems that can result in post-traumatic osteoarthritis. Athletes were divided into six age groups (from 17 to 70 years) and 12 groups based on the downhill gradient they had covered over the last month (from 1,000 to 40,000 m).

RESULTS

Six hundred twenty-one questionnaires were collected from 45% of the participants in the seven races. Multivariate analysis revealed that self-reported KOOS scores were unrelated to age, sex and monthly downhill gradient. Only 74 (12%) of the participants reported previous knee injuries. Significant differences in the five subscales of the KOOS were found between skyrunners with and without previous knee injuries (P<0.01).

CONCLUSIONS

In the studied population, regular training for downhill running and participation in Skyraces could not be considered risk factors for subjective knee symptoms. Skyrunners with self-reported histories of knee injuries scored worse on all five subscales of the KOOS.

The influence of long-term exposure and timing of physical activity on new joint pain and stiffness in mid-age women

OBJECTIVE

To examine the influence of long-term exposure and timing of physical activity (PA) on new joint pain/stiffness in mid-age women.

METHODS

Data were from 5105 participants (born 1946-51) in the Australian Longitudinal Study on Women's Health (ALSWH) who completed survey items on PA (1998, 2001 and 2004) and joint pain/stiffness (2007 and 2010). PA was categorized in five levels at each survey and summed into a cumulative PA score (CPA, range 0-12). Associations were analysed using logistic regression, with separate models for the cumulative model (using CPA), the sensitive periods model (i.e., PA measured at each survey in one regression model) and the critical periods model (i.e., separate regression models for PA at each survey).

RESULTS

951 (18.6%) participants reported new-onset joint pain/stiffness. In the cumulative model, CPA was associated joint pain/stiffness when included as a continuous variable (adjusted odds ratio [OR] = 0.97, 95% confidence interval [CI] = 0.95-0.99), but not when included as a categorical variable. In both the sensitive periods and critical periods models, low to high levels of PA in 2001 and 2004 had stronger inverse associations with joint pain/stiffness than PA levels in 1998. The model fit was better for the sensitive periods than the cumulative or critical periods models.

CONCLUSIONS

In mid-age women, PA between the ages 47 and 58 was associated with a lower risk of joint pain/stiffness 9 years later. Associations were stronger for PA in the last 6 years than for earlier PA.

Determinants of MSK health and disability: lifestyle determinants of symptomatic osteoarthritis

It is frequently considered that, for many people, symptomatic osteoarthritis involving the lower limb joints is a largely preventable 'lifestyle disease'. The purpose of this review is to evaluate the most recent scientific evidence examining the effect of various lifestyle factors, such as physical activity, obesity, diet, smoking, alcohol and injury, on the development of symptomatic knee or hip osteoarthritis. The strengths and weaknesses of various studies are discussed, the magnitude of any demonstrated risks presented and current overall conclusions drawn.

Withaferin A-caused production of intracellular reactive oxygen species modulates apoptosis via PI3K/Akt and JNKinase in rabbit articular chondrocytes

Withaferin A (WFA) is known as a constituent of Ayurvedic medicinal plant, Withania somnifera, and has been used for thousands of years. Although WFA has been used for the treatment of osteoarthritis (OA) and has a wide range of biochemical and pharmacologic activities, there are no findings suggesting its properties on chondrocytes or cartilage. The aim of the present study is to investigate the effects of WFA on apoptosis with focus on generation of intracellular reactive oxygen species (ROS). Here we showed that WFA significantly increased the generation of intracellular ROS in a dose-dependent manner. We also determined that WFA markedly leads to apoptosis as evidenced by accumulation of p53 by Western blot analysis. N-Acetyl-L-Cystein (NAC), an antioxidant, prevented WFA-caused expression of p53 and inhibited apoptosis of chondrocytes. We also found that WFA causes the activation of PI3K/Akt and JNKinase. Inhibition of PI3K/Akt and JNKinase with LY294002 (LY)/triciribine (TB) or SP600125 (SP) in WFA-treated cells reduced accumulation of p53 and inhibited fragmented DNA. Our findings suggested that apoptosis caused by WFA-induced intracellular ROS generation is regulated through PI3K/Akt and JNKinase in rabbit articular chondrocytes.

Relationship between physical activity and chronic musculoskeletal pain among community-dwelling Japanese adults

BACKGROUND

Both little and excessive physical activity (PA) may relate to chronic musculoskeletal pain. The primary objective of this study was to characterize the relationship of PA levels with chronic low back pain (CLBP) and chronic knee pain (CKP).

METHODS

We evaluated 4559 adults aged 40-79 years in a community-based cross-sectional survey conducted in 2009 in Shimane, Japan. We used self-administered questionnaires to assess sociodemographics and health status: PA was assessed by the International Physical Activity Questionnaire, and CLBP and CKP were assessed by a modified version of the Knee Pain Screening Tool. We examined relationships of PA with prevalence of CLBP and CKP using Poisson regression, controlling for potential confounders.

RESULTS

CLBP and CKP were both prevalent (14.1% and 10.7%, respectively) and associated with history of injury, medication use, and consultation with physicians. PA was not significantly related to CLBP or CKP (P > 0.05) before or after adjustment for potential confounders. For example, compared with adults reporting moderate PA (8.25-23.0 MET-hours/week), prevalence ratios for CKP adjusted for sex, age, education years, self-rated health, depressive symptom, smoking, chronic disease history, and body-mass index were 1.12 (95% confidential interval [CI] 0.84-1.50) among those with the lowest PA and 1.26 (95% CI 0.93-1.70) among those with the highest PA (P quadratic = 0.08). The prevalence ratios were further attenuated toward the null after additional adjustment for history of injury, medication use, and consultation (P quadratic = 0.17).

CONCLUSIONS

This cross-sectional study showed that there were no significant linear or quadratic relationships of self-reported PA with CLBP and CKP. Future longitudinal study with objective measurements is needed.

Melatonin treatment combined with treadmill exercise accelerates muscular adaptation through early inhibition of CHOP-mediated autophagy in the gastrocnemius of rats with intra-articular collagenase-induced knee laxity

The purpose of this study was to determine the effects of melatonin intervention on gastrocnemius remodeling in rats with collagenase-induced knee instability. Type VII collagenase was injected into the right knee to induce joint laxity with cartilage destruction. Melatonin (MT; 10 mg/kg) injection was performed twice daily subcutaneously, and treadmill exercise (Ex; 11 m/min) was conducted for 1 hr/day at a frequency of 5 days/wk for 4 wks. The gastrocnemius mass, which was reduced with collagenase injection only (Veh), was increased with collagenase injection with melatonin treatment with and without exercise in the early phase, and the mass in both limbs was significantly different in the Veh compared with the MT group. However, there was an increase in the relative muscle weight to body weight ratio in the Veh group at the advanced stage. Insulin-like growth factor receptor (IGF-IR) was downregulated in the Veh group, whereas IGF-IR was upregulated in the MT and MT + Ex groups. Joint laxity induced enhancement of autophagic proteolysis (LC3 II) in the muscle, which was recovered to values similar to those in the normal control group (Con) compared with those in the MT and MT+Ex groups. Although intra-articular collagenase increased the total C/EBP homology protein (CHOP) levels at 1 wk and decreased them at 4 wks in the Veh group, CHOP in the nucleus was upregulated continuously. Prolonged melatonin treatment with and without exercise intervention suppressed nuclear localization of ATF4 and CHOP with less activation of caspase-3, at the advanced phase. Moreover, the interventions promoted the expression of myosin heavy chain (MHC) isoforms under the control of myogenin. Concomitant with a beneficial effect of melatonin with and without exercise, step length of the saline-injected limb and the collagenase-injected supporting side was maintained at values similar to those in control rats. Taken together, the findings demonstrate that melatonin with and without exercise accelerate remodeling of the gastrocnemius through inhibition of nuclear CHOP in rats with collagenase-induced knee instability.

Intensity-dependent effect of treadmill running on knee articular cartilage in a rat model

OBJECTIVE

To understand the changes of femoral cartilage in response to treadmill running with different intensities in the hope of differentiating "moderate" and "strenuous" running in a rat model.

METHOD

A total of 24 male Wistar rats were randomly assigned into groups of sedentary (SED), low-intensity running (LIR), medium-intensity running (MIR), and high-intensity running (HIR). Rats in LIR, MIR, and HIR groups underwent 8 weeks' treadmill running programs. After sacrificed, femoral condyles were collected to take histomorphometric analysis and immunohistochemistry for collagen II.

RESULTS

Gross and histological observation showed osteoarthritic changes in group HIR. In comparison to SED group, there was significant increase in cartilage thickness, number of chondrocytes, and GAG content in groups LIR and MIR. Conversely, decrease in cartilage thickness, chondrocyte number, and GAG content was found in rats of HIR group, without significant difference though. In addition, in comparison to SED group, HIR group exhibited disorganization of collagen fibril and significantly lower content of collagen type II.

CONCLUSION

An intensity-dependent effect was suggested on the articular cartilage. Our results also demonstrated that running with low-to-medium intensity applied in the present study should be regarded as "moderate" running, whereas high-intensity running as "strenuous" running.

Obesity & osteoarthritis

The most significant impact of obesity on the musculoskeletal system is associated with osteoarthritis (OA), a disabling degenerative joint disorder characterized by pain, decreased mobility and negative impact on quality of life. OA pathogenesis relates to both excessive joint loading and altered biomechanical patterns together with hormonal and cytokine dysregulation. Obesity is associated with the incidence and progression of OA of both weight-bearing and non weight-bearing joints, to rate of joint replacements as well as operative complications. Weight loss in OA can impart clinically significant improvements in pain and delay progression of joint structural damage. Further work is required to determine the relative contributions of mechanical and metabolic factors in the pathogenesis of OA.

Tackling obesity in knee osteoarthritis

Obesity and knee osteoarthritis (OA), two of the most common chronic diseases, are often comorbid. Obesity increases the risk of knee OA by a variety of mechanisms, such as increased joint loading and changes in body composition, with detrimental effects related to metainflammation and behavioural factors, including diminished physical activity and subsequent loss of protective muscle strength. These complex interactions present a challenge to the managing physician. The risk of knee OA related to weight gain and obesity begins from an early age. Weight loss reduces the risk of incident knee OA, and, in established disease, reduces symptoms, improves function and is likely to reduce disease progression. We review strategies to facilitate weight loss, with particular reference to their application in people with knee OA. Although knee OA presents intrinsic barriers to weight management, weight loss is possible at all stages of disease. Exercise or muscle strengthening are desirable for general health and to improve function, but are not essential to achieve weight loss and a successful symptomatic result. The degree of weight loss required to achieve benefit might be greater with increasing disease severity. Finally, we outline the need for a societal approach to tackle obesity-related OA.

Effect of long-term vigorous physical activity on healthy adult knee cartilage

INTRODUCTION

Whether participation in long-term vigorous physical activity affects knee cartilage is unclear and may depend on the state of knee health. We examined the association between vigorous physical activity during a decade and the subsequent changes in knee cartilage among healthy adults. We then examined whether this effect differed in those with and without bone marrow lesions (BMLs), as an indicator of preclinical joint damage.

METHODS

A total of 297 healthy adults age 50-79 yr were recruited. Physical activity was assessed via questionnaire at baseline (1990-1994) and at follow-up (2003-2004), and a score for persistence of vigorous physical activity score was determined. Each subject underwent knee magnetic resonance imaging in 2003-2004 and in 2006-2007. Cartilage volume, defects, and BMLs were measured using validated methods.

RESULTS

Persistent participation in vigorous physical activity was associated with worsening of medial knee cartilage defects (odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.0-2.3). In the subgroup with BMLs, but not in those without BML, persistent vigorous physical activity was associated with a significant worsening of medial knee cartilage defects (OR = 3.4, 95% CI = 1.0-16.5) and a trend toward an increased rate of loss of medial knee cartilage volume (21.6 mm·yr, 95% CI = -0.4 to 43.6).

CONCLUSIONS

In knees with BMLs, persistent participation in vigorous physical activity was associated with adverse cartilage changes in the medial compartment. This suggests that the long-term effects of vigorous physical activity may depend on the preexisting health of the joint.

Induction of osteoarthritis and metabolic inflammation by a very high-fat diet in mice: effects of short-term exercise

OBJECTIVE

To test the hypotheses that obesity due to a very high-fat diet induces knee osteoarthritis (OA), and that short-term wheel-running exercise protects against obesity-induced knee OA by reducing systemic inflammation and metabolic dysregulation.

METHODS

Male C57BL/6J mice were fed either a control diet (13.5% kcal from fat) or a very high-fat diet (60% kcal from fat) from age 12 weeks to age 24 weeks. From 20 to 24 weeks of age, half of the mice were housed with running wheels. The severity of knee OA was determined by assessing histopathologic features, and serum cytokines were measured using a multiplex bead immunoassay and enzyme-linked immunosorbent assays. Body composition was quantified by dual-energy x-ray absorptiometry, and insulin resistance was assessed by glucose tolerance testing.

RESULTS

Feeding mice with a very high-fat diet increased knee OA scores and levels of serum leptin, adiponectin, KC (mouse analog of interleukin-8 [IL-8]), monokine induced by interferon-γ (CXCL9), and IL-1 receptor antagonist to an extent in proportion to the gain in body fat (3-fold increase in percent body fat compared to controls). Wheel-running exercise reduced progression of OA in the medial femur of obese mice. In addition, exercise disrupted the clustering of cytokine expression and improved glucose tolerance, without reducing body fat or cytokine levels.

CONCLUSION

Obesity induced by a very high-fat diet in mice causes OA and systemic inflammation in proportion to body fat. Increased joint loading is not sufficient to explain the increased incidence of knee OA with obesity, as wheel running is protective rather than damaging. Exercise improves glucose tolerance and disrupts the coexpression of proinflammatory cytokines, suggesting that increased aerobic exercise may act independently of weight loss in promoting joint health.

Effect of leisure time physical activity on severe knee or hip osteoarthritis leading to total joint replacement: a population-based prospective cohort study

BACKGROUND

Studies on leisure time physical activity as risk factor or protective factor for knee or hip osteoarthritis (OA) show divergent results. Longitudinal prospective studies are needed to clarify the association of physical activity with future OA. The aim was to explore in a prospective population-based cohort study the influence of leisure time physical activity on severe knee or hip OA, defined as knee or hip replacement due to OA.

METHODS

Leisure time physical activity was reported by 28320 participants (mean age 58 years (SD 7.6), 60% women) at baseline. An overall leisure time physical activity score, taking both duration and intensity of physical activities into account, was created. The most commonly reported activities were also used for analysis. The incidence of knee or hip replacement due to OA over 11 years was monitored by linkage with the Swedish hospital discharge register. Cox's proportional hazards model (crude and adjusted for potential confounding factors) was used to assess the incidence of total joint replacement, or osteotomy (knee), in separate analyses of leisure time physical activity.

RESULTS

There was no significant overall association between leisure time physical activity and risk for knee or hip replacement due to OA over the 11-year observation time. For women only, the adjusted RR (95% CI) for hip replacement was 0.66 (0.48, 0.89) (fourth vs. first quartile), indicating a lower risk of hip replacement in those with the highest compared with the lowest physical activity. The most commonly reported activities were walking, bicycling, using stairs, and gardening. Walking was associated with a lower risk of hip replacement (adjusted RR 0.76 (95% CI 0.61, 0.94), specifically for women (adjusted RR 0.75 (95% CI 0.57, 0.98)).

CONCLUSIONS

In this population-based study of middle-aged men and women, leisure time physical activity showed no consistent overall relationship with incidence of severe knee or hip OA, defined as joint replacement due to OA, over 11 years. For women, higher leisure time physical activity may have a protective role for the incidence of hip replacement. Walking may have a protective role for hip replacement, specifically for women.

Intensive lifestyle intervention improves physical function among obese adults with knee pain: findings from the Look AHEAD trial

Lifestyle interventions have resulted in weight loss or improved physical fitness among individuals with obesity, which may lead to improved physical function. This prospective investigation involved participants in the Action for Health in Diabetes (Look AHEAD) trial who reported knee pain at baseline (n = 2,203). The purposes of this investigation were to determine whether an Intensive Lifestyle Intervention (ILI) condition resulted in improvement in self-reported physical function from baseline to 12 months vs. a Diabetes Support and Education (DSE) condition, and whether changes in weight or fitness mediated the effect of the ILI. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function subscales, and WOMAC summary score. ILI participants exhibited greater adjusted mean weight loss (s.e.) vs. DSE participants (-9.02 kg (0.48) vs. -0.78 kg (0.49); P < 0.001)). ILI participants also demonstrated more favorable change in WOMAC summary scores vs. DSE participants (β (s.e.) = -1.81 (0.63); P = 0.004). Multiple regression mediation analyses revealed that weight loss was a mediator of the effect of the ILI intervention on change in WOMAC pain, function, and summary scores (P < 0.001). In separate analyses, increased fitness also mediated the effect of the ILI intervention upon WOMAC summary score (P < 0.001). The ILI condition resulted in significant improvement in physical function among overweight and obese adults with diabetes and knee pain. The ILI condition also resulted in significant weight loss and improved fitness, which are possible mechanisms through which the ILI condition improved physical function.

Functional adaptation of knee cartilage in asymptomatic female novice runners compared to sedentary controls. A longitudinal analysis using delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC)

OBJECTIVE

To longitudinally estimate the change in glycosaminoglycan content of knee cartilage in asymptomatic untrained female novice runners participating in a Start To Run program (STR) compared to sedentary controls.

METHOD

Nine females enrolling in a 10-week STR and 10 sedentary controls participated voluntarily. Prior to and after the 10-week period, both groups were subjected to dGEMRIC imaging. dGEMRIC indices of knee cartilage were determined at baseline and for the change after the 10-week period in both groups. Based on a self-reported weekly log, physical activity change during the study was depicted as decreased, unchanged or increased. The Mann-Whitney U and Kruskal-Wallis tests were applied to test the hypotheses that dGEMRIC changes occurred between groups and according to physical activity changes respectively.

RESULTS

No significant differences were established between groups for dGEMRIC indices at baseline (P=0.541). A significant positive change of the median dGEMRIC index in the runners group was demonstrated when compared to the controls [+11.66ms (95% CI: -25.29, 44.43) vs -9.56ms (95% CI: -29.55, 5.83), P=0.006]. The change in dGEMRIC index differed significantly according to physical activity change (P=0.014), showing an increase in dGEMRIC index with increasing physical activity.

CONCLUSION

Since cartilage appears to positively respond to moderate running when compared to a sedentary lifestyle, this running scheme might be considered a valuable tool in osteoarthritis prevention strategies. Caution is warranted when applying these results to a wider population and to longer training periods.

The protective effect of tetramethylpyrazine on cartilage explants and chondrocytes

AIMS OF STUDY

Ligusticum wallichi Franchat (chuanxiong) is a very common traditional Chinese herbal medicine in China. Tetramethylpyrazine (TMP) is a major active ingredient extracted from Ligusticum wallichi Franchat. We investigated the protective effect of TMP on interleukin-1β (IL-1β) induced proteoglycan (PG) degradation and apoptosis in rabbit articular cartilage and chondrocytes.

MATERIALS AND METHODS

Rabbit articular cartilage explants and chondrocytes were cultured with 10 ng/ml IL-1β for 72 h in the absence or presence of various concentrations of TMP (50, 100 or 200 μM). Cartilage and chondroprotective effects of TMP were determined by evaluating (1) the degree of PG degradation by measuring the amount of glycosaminoglycan (GAG) released into the culture media with 1,9-dimethylmethylene blue (DMMB) assay in cartilage explants; (2) gene expression of MMP-3 and TIMP-1 by real-time quantitative reverse transcription-polymerase chain reaction analysis in cartilage explants; (3) chondrocytes viability with MTT assay; (4) the production of intracellular reactive oxygen species (ROS) with laser scanning confocal microscopy (LSCM). Anti-apoptotic effects of TMP were determined by measuring (1) apoptosis with flow cytometric analysis; (2) mitochondrial membrane potential assay with LSCM; (3) caspase-3 activity with special assay kit.

RESULTS

IL-1β treatment increased the level of GAG released into the culture media, and induced the gene expression of MMP-3 and inhibited the gene expression of TIMP-1 in cartilage explants. Moreover, IL-1β treatment decreased the cell viability and mitochondrial membrane potential, and enhanced the level of intracellular ROS, apoptosis rate, and caspase-3 activity in chondrocytes. However, simultaneous treatment with TMP attenuated the IL-1β-induced cartilage and chondrocyte destruction in a dose-dependent manner. TMP showed the decrease of GAG degradation and MMP-3 mRNA production, and the enhancement of TIMP-1 mRNA production in cartilage explants. TMP also increased the cell viability in chondrocytes. Furthermore, TMP inhibited the chondrocytes apoptosis through suppression of ROS production, maintaining of mitochondrial membrane potential and downregulation of caspase-3 activity.

CONCLUSION

These results demonstrate that TMP has the cartilage and chondroprotective effect, which suggest that TMP could act as an agent for pharmacological intervention in the progress of OA.

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

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

Subjects with higher physical activity levels have more severe focal knee lesions diagnosed with 3T MRI: analysis of a non-symptomatic cohort of the osteoarthritis initiative

PURPOSE

To study the prevalence of focal knee abnormalities using 3 Tesla (T) magnetic resonance (MR) studies in relation to physical activity levels in asymptomatic, middle-aged subjects from the osteoarthritis initiative (OAI).

MATERIAL AND METHODS

We analyzed baseline data from 236, 45-55 years old individuals (136 women, 100 men) without knee pain (based on Western Ontario and McMaster University scores) and a body mass index (BMI) of 19-27 kg/m(2). Physical activity levels were determined in all subjects using the Physical Activity Scale for the Elderly (PASE). MR imaging (MRI) at 3T was performed using coronal intermediate-weighted (IW) 2D fast spin-echo (FSE), sagittal 3D dual-echo in steady state (DESS) and 2D IW fat-suppressed (fs) FSE sequences of the right knee. All images were analyzed by two musculoskeletal radiologists identifying and grading cartilage, meniscal, ligamentous and other knee abnormalities using the whole-organ MR imaging score (WORMS) MRI OA scoring method. Statistical significances between subjects with different activity levels were determined using one-way analysis of variance (ANOVA), chi-square tests and a multi-variate regression model adjusted for gender, age, BMI, Kellgren-Lawrence (KL) score and osteoarthritis (OA) risk factors.

RESULTS

Meniscal lesions were found in 47% of the 236 subjects, cartilage lesions in 74.6%, bone marrow edema pattern (BMEP) in 40.3% and ligament lesions in 17%. Stratification of subjects by physical activity resulted in an increasing incidence of cartilage, meniscus and ligament abnormalities, BMEP and joint effusion according to activity levels (PASE). The severity grade of cartilage lesions was also associated with PASE levels and presence of other knee abnormalities was also significantly associated with cartilage defects.

CONCLUSION

Asymptomatic middle-aged individuals from the OAI incidence cohort had a high prevalence of knee abnormalities; more physically active individuals had significantly more and more severe knee abnormalities independently of gender, age, BMI, KL score and OA risk factors. These data therefore also suggest that subjects with higher physical activity levels may be at greater risk for cartilage, meniscus and ligament abnormalities, but the analysis of the longitudinal data will show whether these subjects will demonstrate accelerated progress.

Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany

INTRODUCTION

A number of occupational risk factors are discussed in relation to the development and progress of knee joint diseases (for example, working in a kneeling or squatting posture, lifting and carrying heavy weights). Besides the occupational factors, a number of individual risk factors are important. The distinction between work-related and other factors is crucial in assessing the risk and in deriving preventive measures in occupational health.

METHODS

In a case-control study, patients with and without symptomatic knee osteoarthritis (OA) were questioned by means of a standardised questionnaire complemented by a semi-standardised interview. Controls were matched and assigned to the cases by gender and age. Conditional logistic regression was used in analysing data.

RESULTS

In total, 739 cases and 571 controls were included in the study. In women and men, several individual and occupational predictors for knee OA could be described: obesity (odds ratio (OR) up to 17.65 in women and up to 12.56 in men); kneeling/squatting (women, OR 2.52 (>8,934 hours/life); men, 2.16 (574 to 12,244 hours/life), 2.47 (>12,244 hours/life)); genetic predisposition (women, OR 2.17; men, OR 2.37); and sports with a risk of unapparent trauma (women, OR 2.47 (>or=1,440 hours/life); men, 2.58 (>or=3,232 hours/life)). In women, malalignment of the knee (OR 11.54), pain in the knee already in childhood (OR 2.08), and the daily lifting and carrying of loads (>or=1,088 tons/life, OR 2.13) were related to an increased OR; sitting and smoking led to a reduced OR.

CONCLUSIONS

The results support a dose-response relationship between kneeling/squatting and symptomatic knee OA in men and, for the first time, in women. The results concerning general and occupational predictors for knee OA reflect the findings from the literature quite well. Yet occupational risks such as jumping or climbing stairs/ladders, as discussed in the literature, did not correlate with symptomatic knee OA in the present study. With regards to occupational health, prevention measures should focus on the reduction of kneeling activities and the lifting and carrying of loads as well as general risk factors, most notably the reduction of obesity. More intervention studies of the effectiveness of tools and working methods for reducing knee straining activities are needed.

Case-control study of knee osteoarthritis and lifestyle factors considering their interaction with physical workload

AIMS

The aim of this study is to examine the dose-response relationships between age, "lifestyle factors" (body mass index, tobacco smoking, sports), and symptomatic knee osteoarthritis in a population-based case-control study. Additionally, the study aims to investigate the mode of interaction between body mass index (BMI) and physical workload (occupational kneeling/squatting and lifting/carrying of loads) with respect to the risk of symptomatic knee osteoarthritis.

METHODS

In five orthopedic clinics and five practices, 295 male patients aged 25-70 with radiographically confirmed knee osteoarthritis associated with chronic complaints were recruited. The control group comprised 327 male control subjects. In a structured personal interview, body weight at different ages, body height, cumulative amount of smoking, and cumulative duration of different sports activities until the date of first diagnosis of knee osteoarthritis were elicited. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis. An interaction analysis for the parameters BMI and kneeling/squatting respective lifting/carrying of loads was performed. Population attributable risks (PAR) for knee osteoarthritis were determined for BMI solely and for the combination of BMI with occupational kneeling/squatting and lifting/carrying of loads, respectively.

RESULTS

Age and overweight were strongly associated with the diagnosis of knee osteoarthritis. Compared with persons less than 35 years old, persons who were at least 65 years old had an odds ratio (OR) of 19.0 (95% CI 6.1-58.7) for knee osteoarthritis. Persons with a BMI > or = 28.41 kg/m2 had a strongly elevated risk of knee osteoarthritis (OR 10.8; 95% CI 4.8-24.3) compared to persons with a BMI < 22.86 kg/m2. Heavy tobacco smoking (> or = 55.5 pack years) was associated with a decreased knee osteoarthritis risk in comparison with never-smoking (OR 0.2; 95% CI 0.1-0.5). Ball games (handball, volleyball, basketball) and cycling were associated with symptomatic knee osteoarthritis (OR 4.0; 95% CI 1.8-8.9 and OR 3.7; 95% CI 1.7-7.8 in the highest category of cumulative duration, respectively); to a weaker degree jogging, swimming, and soccer also were positively related to symptomatic knee osteoarthritis. Combining the two parameters, BMI and kneeling/squatting into one variable led to a multiplicative interaction mode for symptomatic knee osteoarthritis. For persons with elevated BMI in combination with moderate to high exposure to occupational kneeling/squatting, the population attributable risk (PAR) was 4%. The PAR for elevated BMI in combination with moderate to high exposure to occupational lifting/carrying of loads was 7%.

CONCLUSIONS

In accordance with the literature, we find a strong association between BMI and knee osteoarthritis risk. Considering the relatively high prevalence of occupational manual materials handling, prevention of knee osteoarthritis should not only focus on body weight reduction, but should also take into account work organizational measures particularly aiming to reduce occupational lifting and carrying of loads.

Patellar cartilage: T2 values and morphologic abnormalities at 3.0-T MR imaging in relation to physical activity in asymptomatic subjects from the osteoarthritis initiative

PURPOSE

To study the interrelationship between patella cartilage T2 relaxation time, other knee abnormalities, and physical activity levels in asymptomatic subjects from the Osteoarthritis Initiative (OAI) incidence cohort.

MATERIALS AND METHODS

The study had institutional review board approval and was HIPAA compliant. One hundred twenty subjects from the OAI without knee pain (age, 45-55 years) and with risk factors for knee osteoarthritis (OA) were studied by using knee radiographs, 3.0-T knee magnetic resonance (MR) images (including intermediate-weighted fast spin-echo and T2 mapping sequences), and the Physical Activity Scale for the Elderly. MR images of the right knee were assessed by two musculoskeletal radiologists for the presence and grade of abnormalities. Segmentation of the patella cartilage was performed, and T2 maps were generated. Statistical significance was determined by using analysis of variance, chi(2) analysis, correlation coefficient tests, the Cohen kappa, and a multiple linear regression model.

RESULTS

Cartilage lesions were found in 95 (79.0%) of 120 knees, and meniscal lesions were found in 54 (45%) of 120 knees. A significant correlation between patella cartilage T2 values and the severity and grade of cartilage (P = .0025) and meniscus (P = .0067) lesions was demonstrated. Subjects with high activity levels had significantly higher prevalence and grade of abnormalities and higher T2 values (48.7 msec +/-4.35 vs 45.8 msec +/-3.93; P < .001) than did subjects with low activity levels.

CONCLUSION

Middle-aged asymptomatic individuals with risk factors for knee OA had a high prevalence of cartilage and meniscus knee lesions. Physically active individuals had more knee abnormalities and higher patellar T2 values. Additional studies will be needed to determine causality.

Relationship of compartment-specific structural knee status at baseline with change in cartilage morphology: a prospective observational study using data from the osteoarthritis initiative

INTRODUCTION

The aim was to investigate the relationship of cartilage loss (change in medial femorotibial cartilage thickness measured with magnetic resonance imaging (MRI)) with compartment-specific baseline radiographic findings and MRI cartilage morphometry features, and to identify which baseline features can be used for stratification of fast progressors.

METHODS

An age and gender stratified subsample of the osteoarthritis (OA) initiative progression subcohort (79 women; 77 men; age 60.9 +/- 9.9 years; body mass index (BMI) 30.3 +/- 4.7) with symptomatic, radiographic OA in at least one knee was studied. Baseline fixed flexion radiographs were read centrally and adjudicated, and cartilage morphometry was performed at baseline and at one year follow-up from coronal FLASH 3 Tesla MR images of the right knee.

RESULTS

Osteophyte status at baseline was not associated with medial cartilage loss. Knees with medial joint space narrowing tended to show higher rates of change than those without, but the relationship was not statistically significant. Knees with medial femoral subchondral bone sclerosis (radiography), medial denuded subchondral bone areas (MRI), and low cartilage thickness (MRI) at baseline displayed significantly higher cartilage loss than those without, both with and without adjusting for age, sex, and BMI. Participants with denuded subchondral bone showed a standardized response mean of up to -0.64 versus -0.33 for the entire subcohort.

CONCLUSIONS

The results indicate that radiographic and MRI cartilage morphometry features suggestive of advanced disease appear to be associated with greater cartilage loss. These features may be suited for selecting patients with a higher likelihood of fast progression in studies that attempt to demonstrate the cartilage-preserving effect of disease-modifying osteoarthritis drugs.