Reactive arthritis

Case history

A 21-year-old male student presents with a 4-week history of a painful, hot, and swollen left knee, low back pain with bilateral buttock pain, and left heel pain. He denies trauma and states the symptoms began acutely. He denies any fever or any other significant arthralgias. Further review of symptoms indicates the patient was treated for a chlamydia infection after he developed dysuria approximately 8 weeks ago (he was treated with a single dose of azithromycin). He admits to unprotected sexual intercourse with a new partner 2 days before the onset of his dysuria. In addition to pain and swelling, the patient reports that he has developed morning stiffness in the left knee and low back that last more than 1 hour. He continues to have episodes of dysuria. The findings of physical examination are significant for a large effusion of the left knee with warmth. Range of motion is slightly diminished. There is tenderness to palpation of the left heel at the site of the Achilles' insertion. Laboratory findings are significant for an erythrocyte sedimentation rate of 35 mm/hour, and both full blood count and uric acid level are within normal limits. He is HLA-B27 positive, rheumatoid factor negative, and antinuclear antibody negative. The synovial fluid analysis is negative for crystals, with a total nucleated cell count of 22,000 cells/microlitre (65% neutrophils). A urethral swab was positive by polymerase chain reaction for Chlamydia trachomatis 9 weeks ago at initial presentation of dysuria. There was no evidence of gram-negative diplococci on Gram stain.