A 28-year-old man comes to the emergency department due to 12 hours of severe right knee pain and swelling. He has had no trauma. The patient drinks 1 or 2 cans of beer on weekends but does not use tobacco or illicit drugs. On physical examination, right knee effusion, erythema, and tenderness are present. Active and passive range of motion is markedly decreased. Other joints are normal. Arthrocentesis is performed, and synovial fluid analysis shows a white blood cell count of 110,000/mm3. Which of the following would provide the best treatment for this patient's condition?
This patient has acute monoarticular arthritis with an effusion, decreased range of motion of the affected joint, and a synovial fluid leukocyte count >100,000/mm3. Septic arthritis (very often due to gonococcus in this patient's age group) is a likely diagnosis, and he should receive antibiotics given the risk of joint destruction, osteomyelitis, and sepsis. Synovial fluid Gram stain and culture can help confirm the diagnosis (although cultures can sometimes be negative with gonococcus). Microscopy can exclude the presence of crystals suggestive of gout and pseudogout, conditions that can also cause acute monoarticular arthritis (gout is associated with alcohol use). However, they typically present at an older age, and the synovial fluid leukocyte count is usually lower (at the lower end of the 20,000-100,000/mm3 range).
(Choice A) Allopurinol is a hypoxanthine isomer that lowers serum uric acid levels. It is prescribed to prevent attacks of acute gouty arthritis but is not useful in the treatment of acute flares.
(Choices C, D, and E) Colchicine reduces the acute inflammation of gouty arthritis by inhibiting neutrophil migration into the inflamed areas. Indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), may be prescribed for pain relief in noninfectious inflammatory arthritis (eg, gout) but would not treat infection. Prednisone is sometimes used in the treatment of gout when there are contraindications to colchicine and NSAIDs.
Educational objective:
A high synovial fluid leukocyte count (>100,000/mm3) and absent crystals on microscopic examination strongly suggest bacterial joint infection. Septic arthritis requires antibiotic treatment to prevent joint destruction, osteomyelitis, and sepsis.