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Atraumatic knee swelling

31 July 2022 at 11:54:22

Obs, bloods (FBC, CRP, Urate), follow Sepsis 6 (if signs of sepsis), XR knee (AP and lateral)

Refer to Ortho on-call if raised infection markers or prosthesis in-situ

There are many reasons for non-traumatic causes of knee pain with swelling. In general, the list of differentials include:

  • gout / pseudogout

  • bursitis

  • septic arthritis (most important to rule out)

  • arthritis

  • patella tendonitis

  • bipartite patella

  • patella dislocation / subluxation

  • bakers cyst

  • referred pain

  • tumours (ask red flag symptoms)


Septic arthritis is most important to rule out. Signs include:

  • rapid onset of red hot swollen knee

  • severe restriction in movement and inability to weight bear

  • usually, only one knee affected

  • may become systemically unwell (fever, sweats)

  • ask about risk factors (recent joint surgery, steroid injection/use, inflammatory joint disease (RA), IVDU, immunosuppression, adjacent skin infection)




IF PATIENT PRESENTS WITH SEPSIS - TREAT ACCORDING TO SEPSIS GUIDELINES


Before referral to ortho oncall, please

  1. obtain full set of obs (BP, HR, RR, temp)

  2. take bloods (FBC, U&Es, CRP, urate level, blood cultures if pyrexia)

  3. obtain XR of the knee

  4. DO NOT start antibiotics UNLESS patient fulfils criteria for sepsis

  5. document your findings and refer to ortho oncall team


 

Knee joint aspiration

DO NOT aspirate knees with prosthesis in-situ (e.g. TKR) in ED, unless patient is very unwell and septic where there could be delays in getting patient to theatre for aspiration.


For native joint aspiration

  1. Equipment: Green needle, 20ml syringe, ChloraPrep stick, x3 sample bottles, sticky plaster, sterile gloves, sick bowl for discarding excess drainage

  2. Landmarks and approach: feel the superolateral corner of the patella, locate the soft spot just below this, mark the entry site with pen or end of needle cap

  3. Aspiration: advance needle aiming to the centre and under the patella. Aspirate as you advance. You may have to change angle of the needle if no aspirate returns. If

  4. Samples: ensure samples are labelled and call the micro lab to let them know you are sending a joint aspirate sample for urgent Gram stain, MC+S and Crystal analysis.

  5. Document procedure and the volume and appearance of the joint aspirate.



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