Arthrocentesis and intraarticular injection

Last updated: December 1, 2023

Summarytoggle arrow icon

Arthrocentesis is a procedure involving the removal of fluid from a joint, most commonly the knee or shoulder. It can be used to diagnose conditions such as septic arthritis and crystal-induced arthropathy, and can provide therapeutic relief (e.g., in hemarthrosis). Intraarticular injection is a related procedure that involves the instillation of therapeutic agents (e.g., glucocorticoids, local anesthetics, platelet-rich plasma), with or without concurrent aspiration, for the treatment of chronic conditions such as arthritis. Relative contraindications for both procedures include bleeding diatheses and overlying cellulitis. To perform aspiration or injection, a needle is inserted into the joint space, guided by landmarks, using a sterile technique; ultrasound may be used as an adjunct. Complications include hemarthrosis and soft tissue injury.

Definitiontoggle arrow icon

Indicationstoggle arrow icon

Diagnostic [1][2]

Therapeutic [1][2]

Do not inject glucocorticoids into a swollen joint if infection has not been ruled out. [1]

Contraindicationstoggle arrow icon

Only perform arthrocentesis on prosthetic joints if infection is suspected, as prosthetics are at high risk for infection. [1]

We list the most important contraindications. The selection is not exhaustive.

Technical backgroundtoggle arrow icon

Equipment sizing [1]

  • Needle size
    • Typically 18 to 22-gauge; determined by the anticipated viscosity of the liquid to be aspirated [2]
    • Length: Consider the depth of soft tissue overlying the affected joint. [2]
  • Syringe size
    • Based on the size of the joint and the amount of fluid return expected
    • A 60-mL syringe is often used for therapeutic decompression of large joints, such as the knee.

Agents for intraarticular injection [1][4]

Synergistic and compatible agents can be combined in the same injection (e.g., triamcinolone plus lidocaine). [5]

Ultrasound [1][4]

  • Helpful adjunct to distinguish between superficial bursitis and intraarticular effusion
  • Use a high-frequency linear probe for maximum resolution.
  • Can help with planning (an anechoic fluid collection confirms effusion) and visualizing the needle position during the procedure

Special considerations

  • Hip arthrocentesis is typically performed by an orthopedic surgeon under radiological guidance. [7]
  • Small joints (e.g., in the finger, hand, or foot) may be difficult to aspirate; empiric treatment is often required. [1]

If clinical features are equivocal or landmarks are obscured, use point-of-care ultrasound to assess the fluid in the joint space. [1]

Landmarks and positioningtoggle arrow icon

Knee, parapatellar approach [1][2]

  • Position: knee in maximum extension or flexed at 15–20°; foot perpendicular to the floor
  • Landmarks
    • Can be approached from either the medial or lateral side
    • The medial parapatellar region is thought to be the easiest site to access. [2]
  • Trajectory
    • Insert the needle 1 cm either medial or lateral to the midpoint of the anterior patellar edge.
    • Direct the needle between the intercondylar femoral notch and the posterior surface.
  • Ultrasound probe placement
    • Place the linear probe over the anterior knee (longitudinal orientation).
    • Identify the patella (echogenic object with shadowing).
    • Move the probe medially and laterally to visualize the joint space under the patella.

Shoulder, anterior approach [1]

Shoulder, posterior approach [2]

Equipment checklisttoggle arrow icon

Procedure/applicationtoggle arrow icon

Accessing the synovial space

  1. Position the patient so that the joint is easily accessible. [2]
  2. Identify landmarks specific to each joint and the intended entry point (see “Landmarks and positioning”).
  3. Confirm the presence of the effusion with ultrasound if indicated.
  4. Prep the skin and maintain a sterile field. [2]
  5. Infiltrate local anesthesia under the skin and along the anticipated needle track.
  6. Insert the needle and syringe into the extensor surface of the joint while maintaining traction on the surrounding skin. [1]
  7. Maintain negative pressure on the syringe during insertion and advance the needle until fluid returns. [1]

To minimize pain, avoid repeated contact with the bone when entering the joint space. [1]

Arthrocentesis steps [1][2]

  1. Access the synovial space.
  2. Aspirate an adequate amount of fluid for diagnostic testing. [2]
  3. Manually compress large joints to facilitate additional fluid removal as needed.
  4. Transfer fluid to collection vials.
  5. Perform intraarticular injection steps, if indicated.
  6. Withdraw the needle and apply a dry dressing.

Intraarticular injection steps [1][2]

  1. Access the synovial space.
  2. Perform arthrocentesis steps, if indicated.
  3. Apply negative pressure to ensure that the needle is not located intravascularly.
  4. Slowly inject the desired agent.
  5. Withdraw the needle and apply a dry dressing.

Avoid injection if there is blood flashback suggestive of an intravascular location of the needle.

Pitfalls and troubleshootingtoggle arrow icon

Aspiration without fluid return [1]

  • Use ultrasound to visualize the effusion.
  • If there is still no fluid return, try an alternative site. [2]

Fluid stops flowing during aspiration [1]

  • Debris or purulent material clogging the lumen of the needle
    • Slightly advance and/or retract the needle.
    • Rotate the needle bevel.
    • Consider a larger needle gauge.
  • All fluid removed from the joint : Massage the joint to push any remaining peripheral fluid toward the needle.

Postprocedure checklisttoggle arrow icon

  • Synovial fluid sent for analysis based on the suspected condition (e.g., septic arthritis, gout)
    • Cell count with differential
    • Gram stain
    • Culture
    • Crystal analysis
    • Additional studies as indicated [1]
  • Fluid sample visually inspected and characteristics noted (e.g., color and clarity) for documentation
  • Procedure documented
  • Pain management provided

Interpretation/findingstoggle arrow icon

Complicationstoggle arrow icon

Arthrocentesis [1]

Intraarticular glucocorticoid injection [1]

We list the most important complications. The selection is not exhaustive.

Referencestoggle arrow icon

  1. Roberts JR. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. Elsevier ; 2018
  2. Reichman EF. Reichman's Emergency Medicine Procedures, 3rd Edition. McGraw Hill Professional ; 2018
  3. Chan BY, Crawford AM, Kobes PH, et al. Septic Arthritis: An Evidence-Based Review of Diagnosis and Image-Guided Aspiration. Am Journal Roentgenol. 2020; 215 (3): p.568-581.doi: 10.2214/ajr.20.22773 . | Open in Read by QxMD
  4. Kayentao K, Ongoiba A, Preston AC, et al. Safety and Efficacy of a Monoclonal Antibody against Malaria in Mali. N Engl J Med. 2022; 387 (20): p.1833-1842.doi: 10.1056/nejmoa2206966 . | Open in Read by QxMD
  5. Galloway J, Bukhari M. Practical guide to joint and soft tissue injection techniques. Prescriber. 2006; 17 (20): p.51-56.doi: 10.1002/psb.433 . | Open in Read by QxMD
  6. Ayhan E, Kesmezacar H, Akgun I. Intraarticular injections (corticosteroid, hyaluronic acid, platelet rich plasma) for the knee osteoarthritis. World J Orthop. 2014; 5 (3): p.315-361.doi: 10.5312/wjo.v5.i3.351 . | Open in Read by QxMD
  7. Chisolm‐Straker M, Singer E, Strong D, et al. Validation of a screening tool for labor and sex trafficking among emergency department patients. J Am Coll of Emerg Physicians Open. 2021; 2 (5).doi: 10.1002/emp2.12558 . | Open in Read by QxMD

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