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.

Oxford knee score 1 year after TKR for osteoarthritis with reference to a normative population: What can patients expect?

Objectives: Total knee replacement (TKR) procedure is commonly carried out in patients with advanced osteoarthritis to reduce pain and increase mobility, with on average 84% rated satisfactory outcome, but some (some suggest 44%) continue to experience debilitating pain. The study aimed to investigate factors affecting pain and function outcomes (using Oxford Knee Score, OKS) one year after TKR, with normative comparison to a reference population. Design: We recruited TKR patients from one hospital (Nottinghamshire, UK); collected pre- and post-operative OKS; graded radiographs for severity of osteoarthritis (K-L grade) in a sub-group. We also collected OKS by postal survey from the local area, calculated age and sex specific normative scores and z-scores of post-operative OKS (Z-OKS). The associations between K-L grade, pre-operative OKS, age, sex, against change in OKS and Z-OKS were analysed. Results: There were 536 TKR cases, 91 in radiographic sub-group and 360 people in reference cohort. Post-operative Z-OKS was associated with K-L grade (ߠ​= â€‹0.368; p<0.001). Change in OKS was associated with K-L grade (ߠ​= â€‹0.247; p â€‹= â€‹0.003); pre-operative OKS (ߠ​= â€‹-0.449; p<0.001); age (ߠ​= â€‹0.276; p â€‹= â€‹0.001); and female sex protective (ߠ​= â€‹-0.213; p â€‹= â€‹0.008). On average TKR patients returned to 74% of their normative age and sex adjusted OKS, with younger women achieving worst outcomes. More severe radiographic osteoarthritis predicted greater improvement and better post-operative outcome when compared to normative population. Conclusion: This study identified factors and provided normative OKS data intended to guide clinicians in counselling patients regarding likely surgical outcomes. This could help manage patients' expectations, aid decision making and increase post-surgery satisfaction rate.