Knee Injection

By admin Last updated Feb 3, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Knee Injection

Knee Injection

Timothy S. Johnson MD

Basics

Description

Knee aspiration commonly is used for diagnostic purposes for effusions of unclear cause.
Injections are used most commonly to treat arthritis.
Indications
- Effusion
- Hemarthrosis
- Infection/septic joint
- Synovitis/arthritis
Equipment
- 18-gauge needle
- 20–60-mL syringes
- Sterile gloves
- Sterile antiseptic solution

Treatment

Aspiration technique (Fig. 1):
- The superolateral approach is the most reliable for aspiration (1).
- Position the patient supine on the examination table with the knee fully extended or with a pillow under the knee.
- Perform a wide sterile preparation of the knee.
- Identify the aspiration site ~1 finger
  breadth proximal to the superior pole of the patella and 1 finger
  breadth lateral to the lateral border of the patella.
- Advance a needle through the skin,
  subcutaneous tissue, and lateral retinaculum into the suprapatellar
  pouch between the anterior femur and the quadriceps tendon from lateral
  to medial.
  
  Fig. 1. Knee injection. A: Lateral view. B: Superior view.
- Aspirate the entire fluid collection.
  - When the syringe is full, clamp the hub of the needle with a sterile clamp.
  - Hold the hub and unscrew the syringe from the needle without removing the needle from the joint.
  - Apply a new syringe to the needle hub and continue aspirating.
  - Repeat these steps as many times as necessary to aspirate the effusion completely.
- Remove the needle and apply a bandage.
- Store the fluid for laboratory analysis (see “Arthrocentesis” chapter)
Pearls
- A wide sterile skin preparation allows for manipulation of the knee and patella during aspiration.
- Milking the effusion up into the suprapatellar pouch allows for a more complete aspiration of fluid.
- Synovium can easily clog the needle tip
  during aspiration; use a large-bore needle (18-gauge or higher) to
  minimize this problem.
- Injecting the skin with lidocaine at the injection/aspiration site is an option for patients concerned about pain.
  - It may allow the patient to tolerate the procedure better.
  - However, it does require an additional needle stick.
  - Alternatively, ethyl chloride sprayed on the skin immediately before the aspiration has a similar effect.
- Never aspirate or inject through cellulitic skin.
Therapeutic injection:
- Injection of corticosteroid:
  - Commonly performed after aspiration of synovial fluid that is not infected
  - The superolateral approach is the most reliable (1).
- If an aspiration was performed:
  - Do not remove the needle from the joint.
  - Simply exchange the aspiration syringe
    with the syringe filled with the injectable and inject the medication
    without changing the needle’s location within the joint.
- If an aspiration was not performed:
  - Identify the landmarks and insertion location as described for the superolateral approach into the suprapatellar pouch.
  - Advance the needle into the pouch.
  - Aspirate a small amount of synovial fluid to confirm intra-articular placement.
  - Once confirmed, inject the medication into the joint.
- Remove the needle and apply a bandage.

P.217

Medication

Lidocaine:
- Can be helpful in controlling pain caused by the injection.
- Also can facilitate diagnostic procedures.
  - Painful knees are examined more easily after injection because of lidocaine’s numbing effect.
  - This effect is particularly helpful in determining the cause of a traumatic knee effusion.
  - Bupivicaine also may be used for a longer numbing effect.
  - On the day of injection, limit activity on the affected knee to activities of daily living.
Corticosteroid:
- Can be useful for controlling pain and inflammation from noninfectious arthritis
- Contraindicated if a septic knee has not been ruled out
- A typical dose for the knee is 1 mL of kenalog (40 mg/mL), usually injected with 4 mL of 1% lidocaine.
- Steroid medication usually takes 2–3 days to have an effect.
  - Manage the patient’s expectations by discussing this delayed pain relief at the time of the injection.
Hyaluronates (2) are indicated for treatment of mild osteoarthritis.

References

1. Wind WM, Jr, Smolinski RJ. Reliability of common knee injection sites with low-volume injections. J Arthroplasty 2004;19:858–861.

2. Miller EH. Viscosupplementation: therapeutic mechanisms and clinical potential in osteoarthritis of the knee. J Am Acad Orthop Surg 2001;9: 146–147.

Additional Reading

Cole BJ, Schumacher HR, Jr. Injectable corticosteroids in modern practice. J Am Acad Orthop Surg 2005; 13:37–46.

Miscellaneous

FAQ

Q: Which approach is least reliable in successfully injecting therapeutic agents into the knee joint?

A: The lateral joint line approach.

Q: Viscosupplementation therapy of the knee is indicated for which type of arthritis?

A: Osteoarthritis.