Abstract #1935 High Prevalence of Symptomatic Knee OA in Elderly Black Women: Role of Obesity and Quadriceps Weakness.
M Nevitt, B Goodpaster, D Felson, A Newman, K Wildy, F harris, S Kritchevsky, E Simonsick, T Harris. San Francisco; Pittsburgh; Boston; Memphis and Bethesda.

2732 black and white men and women [40% black; 49% male], participants in the Health ABC cohort, were studied. This cohort was designed to examine weight-related diseases and disablement in well-functioning elderly in Pittsburgh and Memphis. These elderly participants were investigated in terms of the presence of knee pain [using the WOMAC scale] and the radiographic presence of osteoarthritis [using standing PA semiflexed x-rays]. Quadriceps strength was measured using an isokinetic dynamometer.

Of the four gender-race groups, black women demonstrated the highest prevalence of symptomatic knee OA. They also exhibited the highest average body mass index and greatest degree of quadriceps weakness. In each of the four gender-race groups, greater body mass index and reduced quadriceps strength were associated with an increased risk of having symptomatic knee OA.

Physical activity and access to nutritious low fat foods (including fresh fruits and vegetables) are important component of body weight regulation. Large body size and knee pain associated with knee OA often make weight management and muscle strengthening efforts difficult for older adults who are overweight and obese. Once obesity develops, it is difficult to treat effectively. More attention needs to be directed toward preventing weight gain throughout adulthood to stem the increasing prevalence of symptomatic knee OA in later life.

Abstract #1936 Current Hormone Replacement Therapy and Radiographic Knee and Hip Osteoarthritis in Post-Menopausal African-American And Caucasian Women.
A Dragomir, J Jordan, J Renner, G Luta, M Hochberg, C Helmick. Chapel Hill, NC; Baltimore, MD; and Atlanta, GA.

Postmenopausal women in The Johnston County Osteoarthritis Project were studied with regard to the relationship of hormone replacement therapy use to the presence of radiographic knee and hip osteoarthritis. Of note, use of hormone replacement was defined as self-reported use of hormones, pills, shots or implants. 1589 such post-menopausal women were studied.

Use of hormone replacement therapy was strongly associated, in an inverse fashion, with knee and hip osteoarthritis. Specifically, users of hormone replacement therapy had approximately 1/3 less knee osteoarthritis and 50% less hip osteoarthritis that non-users of hormone replacement.

Editorial Comments: It has been previously shown that use of hormone replacement therapy is protective for radiographic knee and hip OA. The present study has extended this observation to African American women as well. These findings suggest that in addition to other known benefits of hormone replacement therapy in post-menopausal women, that protection from knee and hip osteoarthritis, in both Caucasian and African American women, may also be realized.

Abstract #287 Association of Obesity and Severity of Knee Osteoarthritis is Not Mediated by Shared Genetic Influences.
N Manek, D Hart, T Spector, A MacGregor. London.

Of note, radiographic scores were similar for both right and left knees, as well as for monozygotic and dizygotic twins. The overall heritability score was greater for knee radiographic features than it was for body mass index. The analysis yielded results supporting the conclusion that the effect of body weight on severity of knee OA is largely influenced by environmental factors.

Editorial Comments: Obesity is known to be a major risk factor for both incident and prevalent knee osteoarthritis. Though this association has been consistently observed, the mechanism by which obesity mediates this effect is uncertain, with debate as to whether a metabolic or mechanical link represents the mediating factor. The observed findings support the mechanical mechanism for the observed adverse effect of obesity of knee OA.

Abstract #291 Synovitis Predicts the Arthroscopic Progression of Medial Tibiofemoral Knee Osteoarthritis.
X Ayral, E Pickering, T Woodworth, N Mackillop, M Dougados. Paris; Groton and Sandwich, United Kingdom.

A multicenter study was undertaken to evaluate the relationship of synovitis with the structural severity of knee osteoarthritis. Each studied knee was assessed for (a) pain, (b) radiographic/arthroscopic severity, and (c) arthroscopic evidence of synovitis. The synovium was scored as normal, reactive or inflammatory. 506 patients were studied at baseline, with 498 reassessed at a one year interval.

A relationship between arthroscopic evidence of synovitis and severity of osteoarthritis was observed at baseline as well as with disease progression over the year of follow-up. In particular, the knees with arthroscopic evidence of an inflammatory synovitis demonstrated a greater degree of chondropathy and overall radiographic severity. In addition, those knees that demonstrated an inflammatory synovitis at baseline were associated with a greater degree of osteoarthritis progression over the year of follow-up.

Editorial Comments: This project describes a novel approach to address the relationship of synovitis in the pathogenesis of knee osteoarthritis. The extent to which inflammation of the synovium plays a role in disease development or progression offers an improved understanding of pathophysiology and potential target for therapy. However, a caveat is that the observer who assessed, using arthroscopy, the presence and severity of synovitis also could have seemingly rendered a judgment on the degree/severity of chondropathy. Thus the association of inflammatory synovitis with greater degree of knee osteoarthritis may have been biased, at least in part, by the observer making a determination of one parameter with full knowledge and in full view of the status of the other parameter.

Abstract #1277 Prevalence of Cardiovascular Disease Risk Factors Among U.S. Adults with Osteoarthritis and Rheumatoid Arthritis.
G Singh, J Miller, F Lee, AM Sesti, M Russel. Palo Alto, CA; Waltham, MA and New York, NY.

While rheumatoid arthritis has been linked to increased risk of cardiovascular morbidity and mortality, the prevalence of "traditional" risk factors for cardiovascular disease in these populations is not well known. The investigators examined the profile of both osteoarthritis and rheumatoid arthritis patients in a nationally representative survey. They examined data from the Third National Health and Nutrition Examination Survey, that was conducted from 1988-94.

On the basis of this survey, approximately 24.3 million adult Americans, 35 years of age and older, are estimated to have osteoarthritis. An addition 5.7 million adults are estimated to have rheumatoid arthritis. Of note, the prevalence of hypertension, diabetes mellitus, total cholesterol levels, and serum creatinine levels are higher among adult Americans with osteoarthritis and rheumatoid arthritis than in the general population without arthritis.

Editorial Comments: This study advances our understanding of one potential reason why persons with arthritis experience a greater burden of cardiovascular morbidity than the general population. These data specifically indicate that several traditional cardiovascular risk factors, including hypertension, diabetes mellitus, and hypercholesterolemia are more prevalent among persons with, than among those without, arthritis. These results also suggest a potential therapeutic approach that would be focused upon traditional cardiovascular risk factors, in adult Americans with osteoarthritis and rheumatoid arthritis.

Abstract #614 Reduction of severe joint pain increases joint space width (JSW) in standing extended-view xrays of patients with knee osteoarthritis (OA).
S. Mazzuca, K. Brandt, J. Surber. Indianapolis, IN.
reviewed by Joan Bathon, M.D.

Earlier studies of progression of knee OA have utilized conventional standing extended knee xrays to evaluate joint space width. One potential problem with this methodology is that changes in knee pain may affect knee extension and, therefore, the apparent thickness of cartilage as assessed radiographically by joint space width (JSW). In this study, the investigators compared the effect of changes in knee pain on JSW in the extended view with the semiflexed view (SF) in which radioanatomic positioning of the knee is standardized by fluoroscopy.

Methods: 19 patients with knee OA underwent analgesic/NSAID washout (5 half-lives), after which extended and SF radiographic views of the knee were obtained. Analgesic/NSAID therapy was resumed and repeat xrays in both positions were repeated 2-8 weeks later. Knee pain was assessed by the WOMAC score, and JSW by calipers and magnifying lens.

Results: Changes in mean pain score and JSW are shown below. Patients were grouped according to those in whom pain after washout was severe and responsive to resumption of analgesic/NSAID (SP+/R+), and those whose pain was not severe at washing and/or who did not respond to treatment (SP-/R-). Patients with marked improvement in pain (first column) exhibited significant improvement in JSW in the extended view, but not in the SF-AP view, relative to patients with a more modest improvement in pain.

Conclusions: JSW in standing extended view radiographs of highly symptomatic knee OA can be altered significantly by changes in joint pain. In clinical trials and epidemiologic studies of OA progression using extended view knee radiographs, longitudinal variations in pain may confound changes in the apparent thickness of the articular cartilage.

Editorial Comments: Recent studies suggesting that glucosamine has disease modifying effects in knee OA were based on the assessment of JSW by extended knee radiographs. The validity of the findings has been called into question because of the possibility that reduction in knee pain may allow more knee extension and, therefore, an artifactual increase in JSW. The current study supports this notion and suggests that semi-flexed knee radiographs are preferable for long-term studies of progression of knee OA. However, most studies on progression of knee OA to date have targeted patients with early disease in whom symptoms tend to be milder. The current study would suggest that in this group, the radiographic technique may not in fact be as critical unless their pain progresses substantially over the time of the study period. These issues will require further study and resolution in larger numbers of patients, but it seems prudent at this time to use semi-flexed views for long-term evaluations of progression of knee OA.

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