Acute joint pain- Septic arthritis

Vignette: You are the IMT1 on call on acute TAKE. You have been asked to see a 67 year old gentleman who has presented with a 1 day history of right knee pain and swelling.

Past medical history: Hypertension, Osteoarthritis, Atrial Fibrillation, Type 2 DM
Medications: Metformin 500mg bd, Bisoprolol 2.5mg od, Apixaban 5mg bd, Ibuprofen gel prn
Observations: T – 38.1, HR 102, RR 18, Sats 95% on air, BP 115/60, BM 6.5

Please discuss you approach in this patient.

Model answer: Candidate should assess the patient in a systemic manner. Get full history as able, repeat obs, send off bloods including blood cultures, FBC, U&Es, CRP, LFTs, clotting, may consider d-dimer (if leg swollen too) ,CK (if any hx of falls/long lie), autoimmune/rheumatology tests if worried about spondyloarthropathy.

Examine clinically – focused knee examination that reveals a swollen right knee with tenderness, erythema and warmth.

Ask for appropriate imaging – knee XR

Differential diagnosis: to include Septic arthritis, acute gout/pseudogout, haemoarthrosis, MSK injury, spondyloarthropathies (ankylosing
spondylitis, psoriatic arthritis.)

Management: Analgesia, refer to orthopaedics team for knee aspiration and state clearly what they would send samples for – MC&S, gram stain, cultures and
sensitivities + light microscopy (for crystals)

Further history: Knee aspiration has been done, patient continues to remain pyrexial and in severe pain, now screaming out in pain.

Observations now: T 38.5, HR 110, RR 19, BP 110/60, Sats 95% on air, BM 15.1

How would you manage this patient further?

Candidate should state that they would start antibiotics as per Trust protocol, send out blood cultures if not already done, give antipyrexials + adequate analgesia (NSAIDs if no CI/opiates.) Consider stopping metformin whilst patient is acutely unwell and monitor blood sugar levels. May need to start patient on variable rate insulin infusion. If aspiration results come back positive for joint infection then patient will need irrigation and washout via the T&O team. Further definitive treatment will be guided by the results of knee aspiration