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Background To examine if different rates of total knee replacement (TKR) in two similar cohorts with symptomatic knee osteoarthritis (OA) were associated with different functional impact of disease. Methods Subjects from the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI), persons with or at high risk of OA, had knee radiographs, completed Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) surveys and had TKRs confirmed at each visit. At each visit, subjects were defined as having symptomatic OA (SxOA) if ⩾ knee had pain and radiographic OA or if they had a TKR. WOMAC function scores at each visit were compared by analysis of covariance adjusting for age, sex, body mass index, race, site, depression, comorbidity, painful leg joints and knees affected. Post- TKR function scores were imputed to estimate scores that would have been present without TKR. Results Subjects with SxOA (n > 750 in MOST and in OAI) had a mean age 66 to 67 years; most were women and were White. Subjects were followed 4-5 years. Among those with SxOA, more TKRs were done in MOST (35%) than OAI (19%). Adjusted mean WOMAC function (0-68, 68 = worst) improved from 26.9 to 21.9 in MOST and from 24.5 to 22.0 in OAI (difference between MOST and OAI in change in WOMAC function, p = .01). Estimates of function without TKRs showed function would not have changed in MOST (23.2 at baseline to 22.4). Conclusions Functional status of subjects with knee OA in MOST improved more than in OAI, probably because of higher rates of TKRs. The decline suggests that TKR diminishes the functional impact of OA in the community. [ABSTRACT FROM AUTHOR]

Background: Knee bone shape differs between men and women and the incidence of knee osteoarthritis (OA) is higher in women than in men. Therefore, the purpose of the present study was to determine whether the observed difference in the incidence of knee radiographic OA (ROA) between men and women is mediated by bone shape.Methods: We randomly sampled 304 knees from the OAI with incident ROA (i.e., development of Kellgren/Lawrence grade ≥ 2 by month 48) and 304 knees without incident ROA. We characterized distal femur and proximal tibia shape on baseline radiographs using Statistical Shape Modeling. If a specific bone shape was associated with the risk of incident ROA, marginal structural models were generated to assess the mediation effect of that bone shape on the relation of sex and risk of incident knee ROA adjusting for baseline covariates.Results: Case and control participants were similar by age, sex and race, but case knees were from higher body mass index (BMI) participants (29.4 vs. 27.0; p < 0.001). Women had 49% increased odds of incident knee ROA compared with men (adjusted odds ratio (OR) = 1.49, 95% Confidence Interval (C.I.): 1.04, 2.12). There was an inconsistent mediation effect for tibial mode 2 between sex and incident knee ROA, with an indirect effect OR of 0.96 (95% C.I.: 0.91-1.00) and a direct effect OR of 1.56 (95% C.I.: 1.08-2.27), suggesting a protective effect for this mode. Similar findings were also observed for the mediation effect of tibia mode 10 and femur mode 4. These shape modes primarily involved differences in the angular relation of the heads to the shafts of the femur and tibia.Conclusions: Distal femur and proximal tibia bone shapes partially and inconsistently mediated the relationship between sex and incident knee OA. Women had a higher risk of incident ROA, and specific bone shapes modestly protected them from even higher risk of ROA. The clinical significance of these findings warrant further investigation. [ABSTRACT FROM AUTHOR]

The aim of our study was to evaluate the association between patellar alignment by using magnetic resonance imaging images and radiographic manifestations of patello-femoral osteoarthritis (OA). Subjects were recruited to participate in a natural history study of symptomatic knee OA. We examined the relation of patellar alignment in the sagittal plane (patellar length ratio (PLR)) and the transverse plane (sulcus angle (SA), lateral patellar tilt angle (LPTA), and bisect offset (BO)) to radiographic features of patello-femoral OA, namely joint space narrowing and patellar osteophytes, using a proportional odds logistic regression model while adjusting for age, sex, and bone mass index (BMI). The study sample consisted of 126 males (average age 68.0 years, BMI 31.2) and 87 females (average age 64.7 years, BMI 31.6), 75% of whom had tibiofemoral OA (a Kellgren-Lawrence score of 2 or more). PLR showed a statistically significant association with joint space narrowing and osteophytosis in the lateral compartment. SA showed significant association with medial joint space narrowing and with lateral and medial patellar osteophytosis. LPTA and BO showed significant association with both radiographic indices of the lateral compartment. Clear linear trends were found in association between PLR, LPTA and BO, and with outcomes associated with lateral patello-femoral OA. SA, LPTA, and BO showed linear trends of association with medial joint space narrowing. Results of our study clearly suggest the association between indices of patellar alignment and such features of patello-femoral OA as osteophytosis and joint space narrowing. Additional studies will be required to establish the normal and abnormal ranges of patellar alignment indices and their longitudinal relation to patello-femoral OA.