FACTORS AFFECTING RADIOGRAPHIC PROGRESSION OF KNEE OSTEOARTHRITIS

Objectives-To evaluate the prognostic significance of patient characte ristics and radiographic features at the knee for outcome of knee oste oarthritis. Methods-This was a prospective observational study of 350 osteoarthritic knees. Clinical and radiographic data were obtained on 188 hospital referred patients (mean age 70, range 33-91 years). Resul ts-Median duration of follow up was two years (range 1-5 years). The m ajority of patients (48%) reported deterioration, but 23% experienced improvement in symptoms during the study period. Reported exercise tol erance remained unchanged in the majority (62%) and deteriorated in 35 %. Change at least one individual radiographic feature of osteoarthrit is was seen in 252 (72%) knees: increase in joint space narrowing occu rred in 52%, osteophyte in 32%, cysts in 19%, sclerosis in 14%, and at trition in 30%. Increase in Kellgren grade occurred in 137 (39%) knees . Knee effusion, osteoarthritis at multiple joint sites, and nodal cha nge associated with change in Kellgren grade (odds ratios 1.03, 2.39, and 1.80; 95% confidence intervals (CI) 1.01 to 1.05, 1.16 to 4.93, an d 1.02 to 3.17, respectively); warmth at the knee associated with chan ge in any radiographic feature (odds ratio 2.22; 95% CI 1.19 to 4.14). Development of, or increase in, attrition and joint space narrowing a ssociated with worsening symptoms and function and occurred with incre ased frequency in knees with effusions, clinical warmth and calcium py rophosphate crystals in synovial fluid (p < 0.05). Conclusions-A high rate of change, radiographic more than clinical, was seen in osteoarth ritic knees during this study. Poor clinical and radiographic outcome associated with calcium pyrophosphate crystal deposition and clinical inflammation as reflected by knee effusion and warmth.