From the Guidelines
Ultrasound guidance is recommended for knee aspirates to improve success rates, reduce procedural pain, and minimize complications. When performing knee aspirates, the use of ultrasound guidance is essential, particularly in challenging cases such as small effusions, obese patients, or complex anatomy 1. The American College of Radiology suggests that preaspiration imaging with US, CT, or MRI can be crucial for planning a safe aspiration, and image-guided aspiration is ideal for confirming proper needle placement and reducing vascular complications and injury to nerves 1. Some key benefits of using ultrasound guidance for knee aspirates include:
- Improved success rates
- Reduced procedural pain
- Minimized complications like vessel or nerve injury
- Ability to visualize the suprapatellar recess and guide the needle to the largest fluid collection
- Reduced risk of contaminating normal adjacent tissues The procedure involves using a high-frequency linear transducer to visualize the suprapatellar recess, and after standard sterile preparation, the needle is inserted using either an in-plane or out-of-plane approach while visualizing the needle tip throughout the procedure 1. In cases where blind aspirations are considered, the traditional approach involves inserting the needle at the superolateral or superomedial aspect of the patella, directed toward the intercondylar notch, but this method is not recommended due to the higher risk of complications and lower success rates compared to ultrasound-guided aspiration 1. Proper aseptic technique with skin preparation, sterile gloves, and appropriate needle size is essential for both ultrasound-guided and blind aspirations, but the use of ultrasound guidance provides an additional layer of safety and accuracy 1.
From the Research
Ultrasound-Guided Knee Aspirates
- The use of ultrasound guidance for knee aspirates has been shown to be beneficial, particularly for obese patients, diagnostic injection specificity, safety, and precise targeting of pathology 2.
- Ultrasound-guided aspiration can aid in the earlier establishment of diagnosis in non-trauma cases of effusion, and can provide temporary improvement in clinical parameters, especially in post-traumatic effusion 3.
Comparison of Ultrasound-Guided and Non-Guided Aspiration
- A study comparing fluoroscopy-guided and ultrasound-guided aspiration techniques in the management of periprosthetic joint infection found that ultrasound-guided aspiration had higher sensitivity and specificity, as well as lower costs 4.
- Another study found that ultrasound-guided aspiration and corticosteroid injection, combined with horizontal therapy, resulted in better pain relief and functional improvement in patients with knee osteoarthritis complicated with Baker's cyst 5.
Technical Considerations
- Ultrasound guidance offers advantages such as near-field visualization of the joint and soft tissues, ease of access, portability, and lack of ionization radiation 6.
- The choice of ultrasound-guided or non-guided aspiration may depend on the specific clinical scenario, including the presence of trauma or the need for diagnostic specificity 3, 4.