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Difficulty: HardRheumatology and Immunology

A 26-year-old man presents to the clinic with a 4-day history of a severely swollen, painful right knee, bilateral conjunctival injection, and pain at the left posterior heel. He reports having had a severe diarrheal illness three weeks ago after a camping trip. The patient's vital signs are within normal limits. Arrange the following diagnostic and therapeutic steps in the optimal chronological sequence for managing this patient's condition.

  1. 1Perform diagnostic arthrocentesis of the affected knee to evaluate for crystals and definitively exclude septic arthritis.
  2. 2Confirm the clinical diagnosis of reactive arthritis based on the patient's presentation and the finding of a sterile, inflammatory synovial fluid.
  3. 3Initiate primary pharmacological therapy with a scheduled, maximum-dose nonsteroidal anti-inflammatory drug (NSAID).
  4. 4Administer an intra-articular glucocorticoid injection if the localized joint inflammation fails to improve adequately with systemic NSAID therapy.
  5. 5Initiate systemic therapy with a disease-modifying antirheumatic drug (DMARD), such as sulfasalazine, if the condition progresses to a chronic phase.

Answer

The correct sequence of management for this patient begins with performing a diagnostic arthrocentesis to rule out joint infection. Once a sterile inflammatory fluid confirms the diagnosis of reactive arthritis, initial therapy with high-dose NSAIDs is started. If localized symptoms persist, intra-articular glucocorticoids are administered. Finally, if the disease becomes chronic (lasting more than 3-6 months), systemic therapy is escalated to DMARDs like sulfasalazine.
The correct sequence strictly follows the clinical algorithm for acute mono/oligoarthritis suspected to be reactive arthritis: immediate exclusion of a life-threatening or joint-destroying infection (arthrocentesis), formal diagnosis confirmation (sterile fluid + clinical triad), first-line systemic anti-inflammatory therapy (NSAIDs), step-up local therapy for refractory symptoms (intra-articular steroids), and long-term disease modification (DMARDs) if the condition becomes chronic.

Step-by-Step Solution

1
Perform diagnostic arthrocentesis of the right knee.
Evaluation of synovial fluid for cell count, Gram stain, and culture.
To definitively rule out septic arthritis, which is a critical diagnosis to exclude in any patient with a new-onset, acutely swollen joint.
2
Establish the clinical diagnosis of reactive arthritis.
Confirmation of the diagnosis based on the sterile inflammatory synovial fluid and the classic clinical features following an enteric infection.
Accurate diagnosis dictates the appropriate immunosuppressive or anti-inflammatory management pathway.
3
Initiate high-dose nonsteroidal anti-inflammatory drugs (NSAIDs).
Reduction of acute joint inflammation and symptomatic relief.
NSAIDs are the established first-line medical therapy for the acute phase of reactive arthritis.
4
Administer an intra-articular glucocorticoid injection.
Targeted suppression of localized inflammation in the right knee.
Indicated as step-up therapy when systemic NSAIDs provide inadequate relief for monoarticular or oligoarticular involvement.
5
Escalate to systemic disease-modifying antirheumatic drugs (DMARDs) such as sulfasalazine.
Long-term immune modulation and prevention of joint damage.
Indicated for the subset of patients whose reactive arthritis progresses to a chronic phase lasting beyond 3 to 6 months.

Key Concept

The sequential diagnostic and therapeutic pathway for reactive arthritis requires ruling out joint infection via arthrocentesis first, followed by step-wise medical management starting with NSAIDs, escalating to intra-articular steroids for refractory local disease, and utilizing DMARDs for chronic disease.
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Topics

Rheumatology and Immunology

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