Abstract
A patient without any traumatic history left knee pain with an acute flare and knee effusion. When outpatient arthrocentesis yielded turbid fluid, crystal induced arthritis and prulent arthritis were suspected. The gram stain test was negative and intracellular calcium pyrophosphate dehydrate (CPPD) crystals were seen by compensated polarized light. Staphylococcus aureus was identified. The joint was probably seeded by hematogenous infection. The patient was immediately given antibiotics and was operated on for debridement and closed drainage of his knee joint.
