Emergency Medicine

KNEE ASPIRATION

492 Practical Procedures

KNEE ASPIRATION

INDICATIONS

1 Diagnostic

(i) Remove joint fluid for biochemical testing including

microbiology, cytology and polarizing light microscopy, to

differentiate a septic arthritis from an inflammatory (gouty) or

bloody (haemarthrosis) effusion.

2 Therapeutic

(i) Remove excess fluid or blood from the joint to provide

symptomatic relief, increase mobility and decrease pain in a large

effusion, crystal-induced arthropathy or haemarthrosis.

(ii) Intra-articular steroid injection (first discuss with orthopaedics

or rheumatology consultant).

CONTRAINDICATIONS

1 Local skin cellulitis/infection.

2 Acute fracture or joint prosthesis (may introduce infection).

3 Uncorrected bleeding diathesis (in particular platelets <50 or INR >1.5).

4 Uncooperative patient.

Figure 18.7 Digital nerve block.

(a) Site of needle insertion.

(b) Sites of anaesthetic injection.

(b)

(a)

(b)