A 35-year-old man comes to the clinic with acute right knee pain and swelling. His symptoms have been present for a week and have moderately worsened over this period. The patient is able to bear weight but has significant pain when climbing stairs or walking for extended distances. He attempted treatment with ibuprofen, which provided prompt but only temporary relief. Past medical history is unremarkable, though the patient was seen by his primary care provider for a diarrheal illness 2 weeks before onset of the current symptoms. Examination shows a moderate-sized effusion at the right knee. Cultures of a joint aspirate reveal no bacteria. Which of the following is most likely associated with this patient's joint symptoms?

Question

A 35-year-old man comes to the clinic with acute right knee pain and swelling.  His symptoms have been present for a week and have moderately worsened over this period.  The patient is able to bear weight but has significant pain when climbing stairs or walking for extended distances.  He attempted treatment with ibuprofen, which provided prompt but only temporary relief.  Past medical history is unremarkable, though the patient was seen by his primary care provider for a diarrheal illness 2 weeks before onset of the current symptoms.  Examination shows a moderate-sized effusion at the right knee.  Cultures of a joint aspirate reveal no bacteria.  Which of the following is most likely associated with this patient's joint symptoms?

Quizplus · Accepted Answer

11ec160b_3b6a_3481_9249_77be3e9a27c0_MD0001_00 This patient, a young man with acute lower extremity arthritis and a sterile joint effusion following a gastrointestinal infection, has typical symptoms of reactive arthritis. Reactive arthritis is a spondyloarthropathy that preferentially affects HLA-B27-positive individuals. It typically presents as an asymmetric arthritis of the large joints. Common associated symptoms include conjunctivitis, urethritis, and keratoderma blennorrhagicum. Reactive arthritis is most common following infections with Campylobacter, Shigella, Salmonella, Yersinia, Chlamydia, or Bartonella. The clinical manifestations are caused by immune complexes involving bacterial antigens. However, it does not represent disseminated infection, and joint aspirates are sterile (ie, it is a 'reactive' not infectious arthritis). (Choice A) C1 inhibitor deficiency is associated with hereditary angioedema. C1 inhibitor degrades C1 and prevents excessive complement activation and inflammation. (Choice B) High titers of antistreptolysin O antibody are seen in nonpurulent complications of group A streptococcal infections, such as rheumatic fever and glomerulonephritis. (Choices D and E) Antinuclear antibody and rheumatoid factor are nonspecific markers of autoimmune disease, primarily systemic lupus erythematosus and rheumatoid arthritis, respectively. These conditions are less common in men, do not usually present with acute monoarthritis, and are not associated with recent diarrheal illness. Educational objective: Reactive arthritis is a spondyloarthropathy associated with HLA-B27 that can occur following infection with Chlamydia, Campylobacter, Salmonella, Shigella, or Yersinia. It presents with sterile arthritis due to deposition of immune complexes. __________ References: Diagnosis and classification of reactive arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/24418301)

A 35-Year-Old Man Comes to the Clinic with Acute Right