Written by Chris Thom
Spoon Feed
In this systematic review on the accuracy of ultrasound versus landmark knee arthrocentesis, the ultrasound approach was more successful and associated with improved pain scores.
Ultrasound needle guidance wins again over landmark approach
This systematic review analyzed 13 articles studying landmark versus ultrasound-guided knee injection or arthrocentesis. Outcomes included accuracy and efficacy of injection/aspiration, as well as pain and function scores for those receiving therapeutic knee injections.
There were a cumulative 373 patients in the ultrasound-guided cohort and 327 in the landmark cohort. Cumulative combined accuracy for injection and aspiration was 95.4% (356/373) in the ultrasound guided group versus 82% (268/327) in the landmark group. Benefits were also seen in studies evaluating functional outcomes and visual analog scale pain scores, including post-procedural pain scores after 2 to 6 weeks follow-up after therapeutic knee injection.
How will this change my practice?
I find it extremely helpful to assess joint spaces with POCUS to determine if there is joint fluid present and to guide any subsequent aspiration attempts. The literature on ultrasound guidance being superior to landmark for small and medium joints is well defined. For the knee, one may hear that ultrasound is unnecessary given how large the joint space is. However, not all knee effusions are large or easy to access, and the landmark approach is by no means perfect in facilitating needle placement. This study proves that looking before you leap is appropriate and helpful in ensuring successful knee aspiration or injection.
POCUS pro-tips and clips
For identification of knee effusions and subsequent aspiration, I tend to gravitate toward the suprapatellar joint space. Place the linear probe over the midline patella in the long axis and then slide cephalad until the patella transitions into the quadriceps tendon. Once over the quadriceps tendon, the probe is slid off of midline to either the lateral or medial side and angled in medially to view the distal femur. Joint fluid will appear black and just superficial to the highly echogenic femur. Applying probe pressure will allow you to see the joint fluid disappearing into the other side of the joint and then returning again. You’ll check both the medial and lateral sides to assess for the largest pocket. Aim for that location when doing your arthrocentesis. For small pockets, use the dynamic guidance approach and actively watch the needle as it tracks down towards the joint space.
Source
Accuracy and Efficacy of Intra-articular Knee Injections/Aspirations Under Ultrasound Versus Landmark Guidance: A Systematic Review. Am J Phys Med Rehabil. 2026 Jan 1;105(1):1-11. doi: 10.1097/PHM.0000000000002803. Epub 2025 Jul 23. PMID: 40729535.
