Knee Arthrocentesis

Table of Contents

Table of Contents

Published February 2021; reviewed January 2023

Brandon Fainstad, MD1, Molly Brett, MD1, Lisa Thompson, MD1, Meara Melton, MD2

1 Assistant Professor, Department of Medicine, University of Colorado
2 Fellow in Geriatric Medicine, University of Colorado


  1. Determine appropriate indications and contraindications for an intra-articular knee corticosteroid injection. 
  2. Perform all critical steps of a knee joint injection (except needle insertion) using a high-fidelity simulation-based training under direct preceptor observation. 
  3. Perform all critical steps of a steroid injection of the knee in a clinical environment under direct preceptor observation.

Teaching Instructions

Have the learners watch a brief introductory video, review the clinical checklist, and take the pre-quiz below to assess their own knowledge the day prior to procedure training.

Consider combining simulation with a review of the knee exam (a brief demo as well as practice cases – see below) for a total of ~70 minutes.  Trainees are asked to wear scrubs / loose pants for this training.

Knee exam training

We begin by having the instructor demonstrate a brief ~2 minute knee exam on a volunteer learner. Throughout the demonstration, we explain the clinical context for each exam maneuver (e.g. what hypothesis are we looking to prove/disprove with each maneuver?) and share the accuracy (e.g. likelihood ratio) of various parts of the exam.

Then, trainees break into small groups. They work through cases with one participant serving as clinician and the other as model.  Each case provides a background history; as the “clinician” trainee examines his or her peer, the pertinent physical findings are shared. Finally, the “clinician” is asked for the diagnosis and next steps in management.   

Procedure training:

It is critical that both the learner and instructor treat the simulation like a true clinical encounter.  This provides more opportunity for the instructor to identify and correct learner errors, and to reduce the intrinsic and extrinsic cognitive load for the learner when they perform the procedure in a clinical setting.  Have each learner take turns being the proceduralist with another willing learner or standardized patient serving as the model.  Move through the clinical checklist, step-by-step.  For the simulation, we simply ask the learner to list the potential indications and contraindications.  In the clinical procedure, we ask for the specific indication identified for this encounter and ask the learner to report the historical feature and/or demonstrate the physical exam finding that supports the proposed diagnosis. 

We use a “no-touch technique” for this procedure.  Using non-sterile gloves learners identify all necessary supplies for the procedure.  They draw up the lidocaine and steroid from pre-filled vials of saline while instructors offer suggestions for improved technique.  These tips include cleaning the vial tops with alcohol swabs, using a separate needle for drawing up solutions and for the procedure, injecting air into a vial when drawing up more than 3ccs, and drawing up lidocaine first so a small amount can be injected into the small steroid vial to increase the amount of steroid than can be aspirated. 

After the supplies are prepped, we supervise the correct identification and marking of the superior and lateral edges of the patella.  We have them draw two straight and connecting lines to identify the insertion point, superior-lateral to the patella.  After the site is correctly marked, the learner will sterilize the site using the scrub technique (30 seconds).  Then, while using their non-dominant hand to gently displace the patella laterally, they will use the (CAPPED) injection needle to demonstrate their preferred approach to the injection site (advanced along the same horizontal plane as the femur and patella directed slightly inferiorly underneath the patella).   After providing feedback on the trajectory, the learner verbalizes the next steps of the procedure to its completion by placing a bandaid over the marked site.  


Ideally, the simulation training closely precedes (hours to days) the clinical procedure, allowing for maximal opportunity to reinforce the learning in a clinical setting.  However, this is often not possible.  Either way, the learner should watch the clinical procedure video beforehand and verbally review the steps of the clinical checklist before starting the procedure.   Again, one of the most important and often overlooked steps is the learner's correct identification and demonstration of an appropriate indication. It is important to educate the patient on the value of physical therapy in providing more long-term, sustainable benefits. 


Quiz (10 MCQs)

Interactive version

Printable version

Trainee Video:

  1. Watch this 3-minute video of the clinical procedure for trainees. (

Simulation Training

Instructional Video

Simulation Procedural Checklist

Clinical Procedure

Clinical Procedure Checklist

Supply list

  1. Marker
  2. Lidocaine 1% (5cc)
  3. Triamcinolone 40mg/ml (1cc)
  4. Sterile gloves (optional)
  5. Chlorhexidine swab
  6. 18g needle (for drawing up solution)
  7. *2nd 18g needle for aspiration of a joint effusion*
  8. 21-25g 1.5” needle (for injection)
  9. 5cc syringe
  10. *20-30cc syringe for aspiration of joint effusion”
  11. 2×2 gauze
  12. Band-aid

Example procedure note

Indication (osteoarthritis, aseptic inflammatory arthritis): 
Procedure: Steroid injection of the knee
Performing provider: _ 
Supervising Physician (if applicable): _
Consent: obtained and saved in the chart
Time-out confirming correct procedure, location, and patient (2 identifiers): performed 
Procedure: The superior edge and posterior margin of the lateral edge of the patella were marked with strait-intersecting lines to identify the superior-lateral insertion point.  The area was prepped in the usual sterile manner. Then a 21g needle was inserted into the marked insertion point and advanced to a depth of ~3cm.  Attempt for aspiration was performed without bloody return.  Then a combination of ____cc's of 1% lidocaine and 1cc of 40mg/cc of triamcinolone was injected without resistance or patient discomfort.  The needle was then removed and a bandaid applied over the insertion site. 
Follow-up: The patient tolerated the procedure well without complications.  Standard post-procedure care and return precautions were provided. A consult for physical therapy was also placed and the patient was strongly encouraged to start their physical therapy within the next 4 weeks to improve the long-term benefits of the procedure. 


McNabb, J. W. (2014). A Practical Guide to Joint & Soft Tissue Injections. United States: Wolters Kluwer Health.

AAOS. (2018). Essentials of Musculoskeletal Care. United States: Jones & Bartlett Learning, LLC.

Zuber, T. J. (2002). Knee joint aspiration and injection. American family physician66(8), 1497.

Brandon Fainstad


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