Knee and hip radiographic osteoarthritis features: differences on pain, function and quality of life

The association between radiographic osteoarthritis (OA) and symptoms is inconsistent and variable according to each joint. The purpose of this study is to understand the relation between radiographic OA features, pain, function and quality of life, in knee and hip joints. A cross-sectional study was performed using information from EPIPorto cohort. Data was obtained by interview using a structured questionnaire on social, demographic, behavioural and clinical data. Pain was assessed using a pain frequency score (regarding ever having knee pain, pain in the last year, in the last 6 months and in the last month). Quality of life was evaluated with Short Form 36 (SF-36) and function disability with the Lequesne knee and hip indexes. Radiographic knees and hips were classified using the Kellgren–Lawrence score (KL 0–4). Linear regression and proportional odds ratios estimated the association between radiographic features, pain, function and quality of life. In our study, symptomatic OA (KL ≥ 2 plus joint pain) was 26.0 % in knee and 7.0 % hip joints. In knee, the increase on radiographic score increased the odds to have a higher pain frequency score [1.58 (95 % CI = 1.27, 1.97)] and was associated [adjusted β (95 % CI)] with worst general health [−3.05 (−5.00, −1.09)], physical function [−4.92 (−7.03, −2.80)], role-physical [−4.10 (−8.08, −0.11)], bodily pain [−2.96 (−5.45, −0.48)] and limitations in activities of daily living [0.48 (0.08, 0.89)]. Regarding hip, no significant associations were found between the severity of radiographic lesions and these measures. Radiographic lesions in knee were associated with higher complaints, as far as pain and functional limitations are concerned, compared with hip.