What are the characteristics of the synovial fluid and tissue biopsies in osteoarticular TB?
Synovial fluid analysis reveals elevated protein in virtually all patients with arthritis, whereas low glucose level is seen in 60%. Cell counts are highly variable and range from 1000 to 100,000 cells/mm 3 , but most fall in the 10,000 to 20,000 cells/mm 3 range. Polymorphonuclear cells predominate. Synovial membrane biopsies typically show caseating granulomas in 80% of cases. Osteomyelitis is diagnosed by needle biopsy, which usually reveals granulomata that may or may not be associated with caseating necrosis.