Longitudinal radiologic evaluation of osteoarthritis of the knee.

Radiologic assessment appears to be an objective standard for longterm evaluation of osteoarthritis (OA) and it is inexpensive, quick, simple and noninvasive. We conducted a one year followup study of patients with OA of the knee to evaluate the reproducibility and validity of this evaluation. The intra and interobserver reproducibility of the radiologic variables were evaluated on 275 and 539 patients, respectively, and found to be satisfactory (intraclass coefficient of correlation above 0.70 for the evaluation of the space narrowing of the joint). During the one year followup study, there was a slight but statistically significant deterioration of the joint space narrowing, evaluated on a 6 grade scale on 360 patients (p less than 0.001). The changes in the joint space narrowing were more closely correlated with treatments received by the patients for OA (nonsteroidal antiinflammatory drug (NSAID) intake, synovial fluid aspiration) than with changes in the recorded clinical variables (pain on a visual analog scale, Lequesne algofunctional index). Moreover, some factors such as obesity, generalized OA and flares of OA appeared to be correlated with the deterioration of joint space narrowing. Further studies are necessary to confirm and/or explain the relationship between the deterioration of the joint space narrowing and such factors (i.e., NSAID intake, obesity, flares of OA, generalized OA), which were detected in this study.