[Clinical features of patients with osteoarthritic knees followed by development of rheumatoid arthritis].

We investigated clinical features of patients with osteoarthritic knees followed by development of rheumatoid arthritis (RA) after several year's interval. The subjects were 16 knees of 8 patients with osteoarthritis (OA) including one man and 7 women. The mean age at development of OA knee was 62.8 years (range; 45-73). The mean age at later development of RA was 66.0 years (range; 52-79). The mean follow-up period was 96.4 months (range; 28-191). We evaluated clinical features using the 1987 revised Criteria of the American College of Rheumatology (ACR), laboratory dates including RF, CRP, ESR, the number of joints with RA, and femorotibial angle (FTA). The mean number of features of patients which was fulfilled with the ACR criteria was 3.3 +/- 1.6 at the onset of RA. Only four patients were seropositive through the total follow-up period. The serum level of RF, CRP, and ESR were reduced at the follow-up period. The mean number of the joints involved in RA was 11.0 +/- 5.1 (range; 4-22) and wrist and shoulder joints were involved more frequently than other joints except knees. High tibial osteotomy (HTO) was performed on 5 knees of 3 patients and the mean degree of FTA was 168.8 +/- 1.9 degrees just after surgery. However, 36 months after development of RA, joint destruction and valgus deformity occurred on 3 knees and the mean degree of FTA of 5 knees was ended up to 159.6 +/- 11.3 degrees. Our experiences suggested that RF, CRP, ESR and lesions of other joints should be carefully evaluated in the OA patients with seropositivity or knee hydrarthrosis and that histological analysis for synovium should be assessed by the biopsy at time of HTO or arthroscopic surgery to improve accuracy of diagnosis.