Arthrocentesis (joint aspiration)

A general guideline containing information on indications / contraindications / procedural technique relating to joint aspiration

The principles of anaesthetic administration and use of an aseptic technique are similar for all joints, but the anatomical landmarks for the site of injection will vary. Common joints requiring fluid aspiration and/or steroid injection include the shoulder, elbow and knee joints.


  • Diagnostic
    • Unexplained joint effusion to differentiate a septic from an inflammatory or bloody mono-arthritis.
    • Remove joint fluid for cytology, microbiology and biochemical testing.
  • Therapeutic
    • Remove excess fluid or blood from joint to provide symptomatic relief, increase mobility and decrease pain in large effusions, crystal-induced arthropathy or haemarthrosis.
    • Intra-articular steroid injections (must first discuss with orthopaedics or rheumatology consultant).


  • Local skin cellulitis/infection
  • Acute fracture
  • Joint prosthesis
  • Uncontrolled bleeding diathesis
  • Anatomically inaccessible joints
  • Uncooperative patient.


  • Sterile dressing pack
  • Syringes: 10 mL, 20 mL, 50 mL
  • Needles: 25G and 21G ´ 2
  • Local anaesthetic (plain lignocaine 1% or 2%)
  • Sterile gloves
  • Skin cleaning solution (e.g. chlorhexidine or povidone-iodine solution)
  • Sterile specimen containers (´ 3)
  • Sterile fenestrated drape
  • Sticking plaster
  • Alcohol swab
  • Absorbent pad or ‘bluey’.

Procedural Technique

  • Explain the procedure to the patient.
  • Position the patient comfortably on a bed with the affected joint fully exposed.
  • Examine the joint fully; ascertain the site where there is maximal fluid felt, and define anatomical landmarks.
  • Identify the proposed puncture site with a skin marker pen, or make a mental note.
  • Wash hands thoroughly and put on sterile gloves.
  • Clean the skin over the joint with povidone-iodine or chlorhexidine solution and place fenestrated drape over area. Allow skin to air dry.
  • Wipe over the proposed puncture site with an alcohol swab prior to infiltrating anaesthetic if using povidone-iodine solution (as small amount of contamination may inhibit bacterial culture growth).
  • Draw up 10 mL lignocaine and infiltrate the surface of the skin over the entry site using the 25G needle. Wait 45–60 seconds.
  • Switch to the 21G needle and infiltrate the surrounding subcutaneous tissue with local anaesthetic. Avoid injecting lignocaine actually into the joint, as it is bactericidal. Wait for 45–60 seconds for anaesthetic to take effect.
  • Attach the second 21G needle onto a 20-mL syringe. Stabilise the joint by holding the skin taut over the joint effusion with the non-dominant hand, and ‘milk’ the effusion fluid towards the point of the needle.
  • Advance the needle slowly along the anaesthetised track, maintaining a slight negative pressure.
  • Observe for flashback of joint fluid as the joint capsule is breached and slowly aspirate the fluid from the joint. Keep the needle as steady as possible, without touching the bone or cartilage surfaces (painful!).
  • Do not apply too great a negative pressure on the syringe as it will cause the local tissues to collapse onto and occlude the needle bevel.
  • Massage the area surrounding the needle insertion site over the joint to increase the local accumulation of effusion.

Diagnostic Tap

  • Aspirate 15–20 mL fluid from the joint, and then withdraw the syringe and needle. Apply firm pressure over the puncture site and apply a sticking plaster.
  • Transfer 5 mL of fluid to each of the three sterile containers, and label for cytology, microbiology and biochemistry.

Therapeutic tap

  • Aspirate the first 15–20 mL of fluid from the joint and disconnect the syringe, leaving the needle in place.
  • Attach a second syringe (20 mL or 50 mL) and continue this procedure until sufficient fluid has been drained.
  • Alternatively attach a three-way tap first, which avoids the need to change aspirating syringe that may be emptied when full.
  • Apply a firm crepe bandage around the joint if a large volume of fluid has been removed.


  • Joint infection—introduction of skin commensals with poor aseptic technique may result in septic arthritis
  • Haemarthrosis, haemorrhage
  • Synovial fistula.

Date implemented – 05/2009
Revision date – currently being revised
Author – Mike Cadogan

Dr James Wheeler
Dr James Wheeler

Emergency Physician, SCGH, WA, Australia

Articles: 500

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.