Figure 2.

Ultrasound-guided arthrocentesis should be performed by first assessing the joint space for an effusion followed by direct observation of the needle entering the effusion. Use of ultrasound-guided arthrocentesis is highly accurate compared to blind or landmark-techniques for smaller joint spaces such as the tibiotalar joint demonstrated in the image above. Landmarks within the ultrasound image include the bone appearing as a hyperechoic region with superficial tissues including tendons and muscle appearing as heterogenous echoic regions. Fluid within the joint space appears as hypoechoic shapes that conform to the space. Single white arrow indicates the tibia; double white arrow indicates the talus. Star indicates the tibiotalar effusion.