Although some training is required, intra-articular injections are no longer considered an orthopedic subspecialty procedure, and there are a number of benefits to incorporating these injections into your practice. Many patients appreciate their primary care clinician making available services that traditionally required a referral to a specialist. Patients also avoid treatment delays.
Here is a step-by-step guide to familiarize you with the technique.
STEP 1: Selecting an injection approach
Common approaches for injecting the knee include the following1 :
- Anterolateral (flexed knee)
- Anteromedial (flexed knee)
- Superolateral/lateral suprapatellar (straight knee)
- Superomedial/medial suprapatellar (straight knee)
- Lateral mid-patellar
- Medial mid-patellar.
One study found that the accuracy of the first attempt at needle placement was highest for lateral mid-patellar (93%) compared with anteromedial (75%) and anterolateral (71%) approaches (superolateral approach not done).
STEP 2: Identify and mark the injection site2
For superolateral approach:
- Palpate superolateral and lateral edges of patella with patient supine and leg straight
- Mark where lines intersect as in diagram.
If the patient cannot completely extend the knee, placement of a rolled towel to support the knee will help provide the patient comfort and minimize muscle spasm, improving the likelihood of a successful and comfortable injection.
STEP 3: Preparing the injection site2
- Aseptic technique
- – Swab area 3 times with a povidone iodine preparation (Beta-dine) and let dry.
- Local anesthetic options
- – Lidocaine
- – Vapocoolant spray
STEP 4: Aspiration (skip to Step 5 if no effusion is present)
If effusion is present, aspiration of the effusion can relieve patient discomfort, be of diagnostic benefit, and avoid dilution of a visco-supplement to be injected.2
- Insert 1 ½” 18-gauge needle for aspiration3
- If needle is accurately placed, the syringe should fill with fluid1
- Compression of the opposite side of the joint or the patella may aid in arthrocentesis.3
STEP 5: Injection
If aspiration was required, the same needle can be used for aspiration and injection by changing the syringe.
- Insert needle (1 ½”, 21-gauge for corticosteroids; 1 ½”, 20- or 22-gauge for viscosupplementation) ¾” to 1 ¼” for injection
- Remove needle, wipe off povidone iodine solution, and apply bandage.
Post-injection care: Setting patient expectations and managing adverse effects
- Patient should avoid strenuous activity for 1 to 2 days after injection and apply ice to injection site
- Mild pain or swelling at the injection site can occur, but is rare
- – If mild pain or swelling occurs, recommend ice, nonsteroidal anti-inflammatory drug (NSAID), rest, and elevation
- – If significant pain or swelling occurs:
- Joint aspiration
- Send aspirate to lab to rule out joint infection
- Crystal analysis
- May provide intra-articular corticosteroid to decrease pain and inflammation after viscosupplementation if infection has been excluded.