Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weightbearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability. Ann Intern Med. 2000;133:635-646. www.annals.org For author affiliations and current addresses, see end of text.

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Osteoarthritis: New Insights Part 1: The Disease and Its Risk Factors

https://www.rheumatic.theclinics.com/article/S0889-857X(08)00041-0/pdf

Epidemiology of Osteoarthritis

and Introduction Abstract Study Design: Review and reinterpretation of existing literature. Objective: To suggest how intervertebral disc degeneration might be distinguished from the physiologic processes of growth, aging, healing, and adaptive remodeling. Summary of Background Data: The research literature concerning disc degeneration is particularly diverse, and there are no accepted definitions to guide biomedical research, or medicolegal practice. Definitions: The process of disc degeneration is an aberrant, cell-mediated response to progressive structural failure. A degenerate disc is one with structural failure combined with accelerated or advanced signs of aging. Early degenerative changes should refer to accelerated age-related changes in a structurally intact disc. Degenerative disc disease should be applied to a degenerate disc that is also painful. Justification: Structural defects such as endplate fracture, radial fissures, and herniation are easily detected, unambiguous markers of impaired disc function. They are not inevitable with age and are more closely related to pain than any other feature of aging discs. Structural failure is irreversible because adult discs have limited healing potential. It also progresses by physical and biologic mechanisms, and, therefore, is a suitable marker for a degenerative process. Biologic progression occurs because structural failure uncouples the local mechanical environment of disc cells from the overall loading of the disc, so that disc cell responses can be inappropriate or aberrant. Animal models confirm that cell-mediated changes always follow structural failure caused by trauma. This definition of disc degeneration simplifies the issue of causality: excessive mechanical loading disrupts a disc's structure and precipitates a cascade of cell-mediated responses, leading to further disruption. Underlying causes of disc degeneration include genetic inheritance, age, inadequate metabolite transport, and loading history, all of which can weaken discs to such an extent that structural failure occurs during the activities of daily living. The other closely related definitions help to distinguish between degenerate and injured discs, and between discs that are and are not painful.

What is intervertebral disc degeneration, and what causes it?

Objective. —To determine the effects of structured exercise programs on self-reported disability in older adults with knee osteoarthritis. Setting and Degign. —A randomized, single-blind clinical trial lasting 18 months conducted at 2 academic medical centers. Participants. —A total of 439 community-dwelling adults, aged 60 years or older, with radiographically evident knee osteoarthritis, pain, and self-reported physical disability. Invervention. —An aerobic exercise program, a resistance exercise program, and a health education program. Main Outcome Measures. —The primary outcome was self-reported disability score (range, 1-5). The secondary outcomes were knee pain score (range, 1-6), performance measures of physical function, x-ray score, aerobic capacity, and knee muscle strength. Results. —A total of 365 (83%) participants completed the trial. Overall compliance with the exercise prescription was 68% in the aerobic training group and 70% in the resistance training group. Postrandomization, participants in the aerobic exercise group had a 10% lower adjusted mean (±SE) score on the physical disability questionnaire (1.71 ±0.03 vs 1.90±0.04 units; P Conclusions. —Older disabled persons with osteoarthritis of the knee had modest improvements in measures of disability, physical performance, and pain from participating in either an aerobic or a resistance exercise program. These data suggest that exercise should be prescribed as part of the treatment for knee osteoarthritis.

https://jamanetwork.com/journals/JAMA/articlepdf/412600/jama_277_1_028.pdf

A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST)

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1529-0131%28199808%2941%3A8%3C1343%3A%3AAID-ART3%3E3.0.CO%3B2-9

An update on the epidemiology of knee and hip osteoarthritis with a view to prevention

Objective. To determine the relationship between different physical loading conditions and findings of knee osteoarthritis (OA).

Methods. We selected 117 male former top-level athletes (age range 45–68 years) who had participated in sports activities with distinctly different loading conditions: 28 had been long-distance runners, 31 soccer players, 29 weight lifters, and 29 shooters. Histories of lifetime occupational and athletic knee loading, knee injuries, and knee symptoms were obtained, and subjects were examined clinically and radiographically for knee findings of OA.

Results. The prevalence of tibiofemoral or patellofemoral OA based on radiographic examination was 3% in shooters, 29% in soccer players, 31% in weight lifters, and 14% in runners (P = 0.016 between groups). Soccer players had the highest prevalence of tibiofemoral OA (26%), and weight lifters had the highest prevalence of patellofemoral OA (28%). Subjects with radiographically documented knee OA had more symptoms, clinical findings, and functional limitations than did subjects without knee OA. By stepwise logistic regression analysis, the risk for having knee OA was increased in subjects with previous knee injuries (odds ratio [OR] 4.73), high body mass index at the age of 20 (OR 1.76/unit of increasing body mass index), previous participation in heavy work (OR 1.08/work-year), kneeling or squatting work (OR 1.10/work-year), and in subjects participating in soccer (OR 5.21).

Conclusion. Soccer players and weight lifters are at increased risk of developing premature knee OA. The increased risk is explained in part by knee injuries in soccer players and by high body mass in weight lifters.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780380413

Knee osteoarthritis in former runners, soccer players, weight lifters, and shooters

Study design Historical cohort, including selected subgroups. Objectives To understand the long-term effects of exercise on back-related outcomes, back pain, sciatica, back-related hospitalizations, pensions, and magnetic resonance imaging findings were studied among former elite athletes. Summary of background data Exercise and sports participation have become increasingly popular, as have recommendations of exercises for back problems, but little is known about their long-term effects. Methods Questionnaires were returned by 937 former elite athletes and 620 control subjects (83% response rate). Identification codes allowed record linkage to hospital discharge and pension registers. Magnetic resonance images were obtained of selected subgroups with contrasting physical loading patterns. Results Odds ratios for back pain were lower among athletes than among control subjects, with significant differences in endurance, sprinting and game sports, and wrestling and boxing. No differences in the occurrence of sciatica or in back-related pensions and hospitalizations were seen. When comparing lumbar magnetic resonance images of 24 runners, 26 soccer players, 19 weight lifters, and 25 shooters, disc degeneration and bulging were most common among weight lifters; soccer players had similar changes in the L4-S1 discs. No significant differences were seen in the magnetic resonance images of runners and shooters. Conclusions Maximal weight lifting was associated with greater degeneration throughout the entire lumbar spine, and soccer with degeneration in the lower lumbar region. No signs of accelerated disc degeneration were found in competitive runners. However, back pain was less common among athletes than control subjects and there were no significant differences in hospitalizations or pensions. No benefits were shown for vigorous exercise compared with lighter exercise with respect to back findings.

Heli Paananen

Papers

Knee osteoarthritis in former runners, soccer players, weight lifters, and shooters

The long-term effects of physical loading and exercise lifestyles on back-related symptoms, disability, and spinal pathology among men.