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| Jon Giles, M.D., and Kevin Fontaine, Ph.D.
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Abstract 1775: Joints Involved, Severe Pain, Activity limitation and Doctor-Diagnosed Arthritis among Adults with Chronic Joint Symptoms, United States, 2002 Purpose: Data from 31,044 respondents of the 2002 National Health Interview Survey (NHIS) were used to estimate the frequency and site of affected joints among adults reporting chronic joint symptoms (CJS), and to determine the relationship between joints affected and likelihood of arthritis diagnosis, pain severity, and activity limitation among a large, nationally representative sample of US adults. Methods: For this study CJS was defined as joint pain, aching and stiffness during the past 30 days with symptoms onset of over 3 months. Respondents reported which joints were affected, whether they had ever been told by a health care provider that they had some form of arthritis, their average pain level (severe pain defined as a rating of 7 or greater), and if their activity level had been affected by the joint symptoms. To account for the complex sampling design of the NHIS, SUDAAN statistical software was used to derive nationally representative estimates. Logistic regressions were calculated (with persons with 1 affected joint serving as the reference category) to evaluate associations between number of affected joints and the odds of having doctor-diagnosed arthritis, severe pain, and activity limitation. Results: Nearly 25% (51.4 million) of US adults are estimated to report CJS. Among those reporting CJS the joints most affected were the knee (58%), the shoulder (30%), the fingers/thumb (27%), the hip (24%), and the ankle (22%). The prevalence of the number of joints affected and the odds ratios (OR) for the logistic regression analysis on diagnosed arthritis, severe pain, and activity limitation are shown below:
Conclusions: One quarter of the US adult population report CJS and nearly 5 million report CJS in 4 or more joints. The greater the number of affected joints the greater the odds of reporting doctor diagnosed arthritis, severe pain, and activity limitation. Editorial Comments: Consistent with previous research, this study suggests that a substantial proportion of US adults report CJS. Although the NHIS does not adequately assess the particular type of arthritis present, it is likely that inflammatory arthritis is the predominant form reported by US adults. As the population ages and becomes heavier (two major arthritis risk factors) we can anticipate that an even greater proportion of US adults will report CJS and arthritis in the coming years. Since, as this study indicates, a greater number of affected joints associates in a linear way with arthritis, severe pain, and activity limitations, it is vital to reduce the prevalence of risk factors for developing arthritis so we can stem the growing tide of arthritis and its associated physical, social, and societal consequences. Moreover, the results of this study underscore the importance of early intervention to alter progression and reduce the myriad of burdens associated with this disease. Abstract 1973: The Course of Functional Status and Pain in Osteoarthritis (OA) of the Hip and Knee: A Systematic Review Editorial Comments: There is a critical need for methodologically rigorous studies that evaluate the natural history of functional status and pain in adults with knee and/or hip OA. Although this systematic review suggests that there might be factors that predict deterioration and preservation of functional status the current evidence for such factors is scant and only speculative at best. The results of this literature review underscore the need to conduct these important studies so we can develop and evaluate optimal interventions to preserve functional status and control pain in OA sufferers over the long-term. The ongoing 7-year NIH and industry-sponsored Osteoarthritis Initiative (OAI), a longitudinal observational study of adults > 45 years old either at risk for developing OA or early in the disease course should help shed light on the what happens to functional status and pain over time. The OAI may also help us to better learn to diagnose, monitor, and treat OA to optimally preserve function and control pain. Abstract 1848: Current Smoking Increases the Risk for Cartilage Loss at the Knee in Older Men Data from animal studies has suggested that smoking may have a detrimental effect on cartilage, perhaps mediated by tissue hypoxia and elaboration of destructive reactive oxygen species at the level of articular cartilage. However, results from epidemiologic studies in humans have tended to show no association. This may be mediated, in part, by a decrease in BMI associated with smoking that may confound the association in epidemiologic studies. In order to better elucidate the effect of smoking, Amin et al examined knee cartilage loss in men according to current smoking status. Methods: Men enrolled in the Boston OA Study of the Knee were studied. Women were excluded as less than 5% of women enrolled in the study were current smokers. Enrolled subjects were at least 45 years of age and all had symptomatic knee OA at entry (knee pain and evidence of osteophytes on plain radiographs). Study subjects underwent MRI evaluation of the more symptomatic knee, scored by the WORMS method to quantify regional cartilage volume, at baseline and after 15 and 30 months. Smoking status was assessed by patient report as current, former, or never. Cartilage loss was defined as a change in WORMS score by 1 or more for any of the regions of the tibiofemoral or patellofemoral joints. Results: 159 men had follow-up MRIs with complete analysis. Of these, the mean age was 69 years at enrollment and the mean BMI was 31. 18 (11%) of the subjects were current smokers. Current smokers tended to be younger (62 vs. 69 years, respectively), have lower BMI (29 vs. 31, respectively), have less lateral compartment OA, and report less knee pain than non-smokers or former smokers. Odds of having progressive cartilage loss of the medial, lateral, or patellofemoral compartments in current smokers vs. non- or former smokers
Conclusions: Current smoking is associated with progressive cartilage loss of the medial and patellofemoral compartments compared to non- and former smokers, even after adjusting for age, BMI, knee pain, and physical activity. Editorial Comment: These are interesting findings and help to refute previous results from epidemiologic studies that may have been confounded by the beneficial effects of smoking on BMI. The potential mechanisms linking smoking to cartilage loss are numerous, and likely involve interaction between inflammatory pathways and mechanical/alignment abnormalities. In this sample, women could not be studied secondary to the low prevalence of current smokers; and indeed, the prevalence of current smokers among men in this group is also fairly low suggesting that the volunteers for this study may be healthier, in general, than the general population. However, it is likely that the findings presented here would be more pronounced in a more representative population. An interesting next step from this study would be to investigate the effect of smoking cessation on the risk of knee cartilage loss. Abstract 1850: Goodbye to Shoes: Walking Barefoot Decreases Lower Extremity Dynamic Joint Loading Mechanical loading of the knee joint during lower extremity movement has been correlated with the severity and rate of progression of knee OA. Understanding which forces are associated with poor OA outcomes has prompted studies of the use of customized footwear and orthotics in an effort to reduce potentially pathogenic dynamic forces. However, the effect of normal footwear and even no footwear on dynamic knee loading has not been systematically studied. Here, Shakoor et al examine dynamic knee loading in patients with OA while walking barefoot compared to wearing normal footwear. Methods: Men and women with medial joint knee OA (K/L grade 2 or 3) underwent gait analysis using an optoelectric camera system and multi-component force plates while wearing their normal walking shoes and then immediately after while barefoot. Differences in gait parameters with and without shoes were compared, with the peak external knee adduction moment (PEKAM) used as the primary gait outcome. Gait analyses were matched for speed and normalized for subject weight*height. Results: 65 subjects with medial compartment OA (51 women and 14 men) with a mean age of 58 years were studied. The majority of subjects studied (50 of the 65) had K/L grade 2 knee OA. PEKAM, Hip adduction moment, hip internal rotation, and hip external rotation were all significantly decreased with barefoot walking (11.9%, 5%, 9.2%, and 10.9%, respectively). Other gait parameters, such as stride, cadence, toe out angle, and range of motion at the hip, knee, and ankle were significantly affected by barefoot walking. However, adjustment for these parameters demonstrated no effect on the difference in PEKAM between normal footwear vs. barefoot walking. Conclusions: Barefoot walking is associated with decreased dynamic knee loading compared to walking in normal footwear. Editorial Comment: These are interesting results from a creative project. However, some caution should be taken when interpreting the results. In particular, the investigators only studied gait when initiating barefoot walking, when the placement of the foot and maintenance of the plantar arch may be different than after sustained barefoot walking, when maintenance of the plantar arch may be more relaxed and thus prone to increase medial knee loading. Nevertheless, these results highlight the need for greater understanding of the relationship between mechanical joint loading under normal physiologic conditions and risk for the development and progression of knee OA. Abstract 1852: The Association between Varus Thrust and Meniscal Damage in Knee Osteoarthritis (OA) Both varus thrust during ambulation and medial meniscal damage have been associated with risk of and/or progression of medial compartment knee OA. Here, Marshall et al explore whether ambulatory varus thrust may trigger or exacerbate medial meniscal damage. Methods: The authors conducted a cross-sectional study to examine whether knees with ambulatory varus thrust were more likely to demonstrate prevalent medial meniscal tears. Subjects with symptomatic knee OA (K/L grade > 2 with knee symptoms) underwent visual gait observation for presence or absence of ambulatory varus thrust, bilateral knee MRI, and full limb radiographs for assessment of alignment. MRI scans were scored using the WORMS semi-quantitative scoring system that included grading of 0-2 for medial meniscal extrusion and grading of 0-4 for medial meniscal tears for the anterior horn, posterior horn, and body of the medial meniscus. Results: 380 knees from 218 subjects (77% female) underwent MRI scanning. Subjects were, on average, 68 years of age and had a mean BMI of 31. Association of meniscal extrusion with the prevalence of varus thrust
Significance was lost, however, with adjustment for bone attrition. In addition, 71% of knees with varus thrust exhibited high grade (grade 3-4) meniscal tears compared to only 23% without varus thrust, corresponding to a greater than 8-fold greater odds of having a high grade meniscal tear if varus thrust was present. After adjusting for demographic and OA associated factors there remained a greater than 2-fold odds of having a high grade meniscal tear if varus thrust was present. Conclusions: Ambulatory varus thrust of the knee is associated with both extrusion and high grade tears of the medial meniscus, even after adjusting for demographic and most OA associated factors. Editorial Comment: These are interesting and novel findings that help to fill in gaps in the understanding of the processes contributing to OA of the knee. However, the cross-sectional nature of this study does not allow for any causal relationships to be determined. It is plausible that initial medial meniscal injury could lead to altered knee mechanics and the subsequent development of varus thrust, or equally as plausible that altered knee mechanics secondary to varus thrust could stress the supporting structures of the medial knee, leading to medial meniscal injury. A prospective study, of which several are currently underway, would be required to fully examine the cause/effect relationship suggested here. Understanding these cause/effect relationships has the potential to identify intervention strategies that may be effective in preventing and/or slowing the progression of knee OA. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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