Synovial fluid acidosis correlates with radiological joint destruction in rheumatoid arthritis knee joints.

Metabolic variables in samples of synovial fluid (SF) from 33 rheumatoid arthritis (RA) knees were analyzed. These variables were correlated with radiological destruction and SF proteoglycan concentrations. SF acidosis correlated with radiological involvement (rs = 0.62, p less than 0.002), but not with proteoglycan concentrations. A weak correlation was found between SF acidosis and granulocyte concentrations (rs = 0.37, 0.02 less than p less than 0.05). Metabolic variables covaried as expected. Samples from right and left knees from the same patients correlated regarding cellular and metabolic variables. Our results indicate insufficient nutritional supply in RA joints with increasing radiological involvement.