Cytological assessment of knee effusions.

Effusion fluid from 80 knee joints was obtained from patients prior to arthroscopy and arthroscopic surgery and submitted to independent physicochemical analysis and cytological examination. The majority of the effusions were secondary to osteoarthrosis and traumatic mechanical derangement. These two conditions gave nonspecific findings on physicochemical analysis and cytology, and the cytologist diagnosed on 13% of these correctly. Cytological examination of fluid from rheumatoid knees revealed ragocytes in just over half the cases, and on this basis, the cytologist was able to correctly diagnose rheumatoid arthritis. Contrary to other reports, we conclude that physicochemical analysis and cytological examination of joint fluid is of little value in the assessment of knees presenting to the orthopaedic surgeon.