Knee injections can present a challenge, particularly when dealing with a dry knee or limited joint space. However, with the right approach and the use of ultrasound guidance, practitioners can significantly enhance accuracy while improving patient comfort. This guide covers essential techniques for performing a lateral suprapatellar knee injection, offering valuable insights for clinicians seeking to refine their skills.
Why Use the Lateral Suprapatellar Approach?
The lateral suprapatellar injection is a highly effective technique for delivering medication into the knee joint, particularly in cases involving effusion. When performed with ultrasound guidance, this approach provides several benefits:
- Ensures precise needle placement
- Minimizes patient discomfort with targeted numbing
- Maximizes fluid aspiration to relieve symptoms
By utilizing this technique, practitioners can improve both procedural efficiency and patient outcomes.
Step-by-Step Breakdown of the Injection
1. Understanding the Anatomy
Before performing the injection, it’s essential to visualize key anatomical structures using ultrasound. Important landmarks include:
- Quadriceps tendon
- Suprapatellar fat pad
- Prefemoral fat pad
- Joint effusion
Identifying these structures ensures that the injection is accurately delivered into the joint space.
2. Choosing the Injection Site
Since the effusion is located in the suprapatellar pouch, selecting a lateral entry point approximately 1.5 to 2 centimeters below the skin surface provides the best access for both fluid aspiration and medication delivery.
3. Numbing the Area
To enhance patient comfort, a small-gauge (30-gauge, half-inch) needle is used to inject lidocaine at the entry site. Additionally, numbing the retinaculum is essential, as this structure can be particularly sensitive during the procedure.
4. Performing the Aspiration and Injection
Once the area is numb, an 18-gauge needle is used to aspirate the effusion. The appearance of the extracted fluid can provide valuable diagnostic insights. Clear, straw-colored fluid suggests a relatively fresh effusion, while older fluid may have a thicker, darker consistency resembling honey.
To optimize fluid removal, utilizing a quad flex technique—where the patient gently contracts their quadriceps—helps shift fluid from the lateral and medial gutters into the suprapatellar pouch, making aspiration easier.
5. Final Injection and Post-Procedure Care
With the joint space clear, a steroid injection is administered to reduce inflammation and improve knee function. This approach is particularly beneficial for patients preparing for physical activity or rehabilitation.
Key Takeaways for Practitioners
- Ultrasound guidance improves accuracy and ensures safe needle placement.
- Numbing the retinaculum enhances patient comfort during the procedure.
- Utilizing muscle contraction techniques helps aspirate more fluid effectively.
- The lateral suprapatellar approach is a reliable method for both aspiration and injection.
Learn More with Gulfcoast Ultrasound Institute
Knee injections are just one of many procedures that can be enhanced through ultrasound guidance. To sharpen your skills and advance your practice, Gulfcoast Ultrasound Institute offers top-tier training programs tailored to your needs. Whether you're new to ultrasound or looking to refine advanced techniques, we’re here to help you master the art of ultrasound-guided procedures.
Call us today at 727-363-4500 to learn more about our ultrasound training courses, or visit us at 111 2nd Ave NE, #800, St. Petersburg, FL 33701, to elevate your ultrasound expertise.
