US fibularis (peroneus) longus tendon at ankle joint: Normal and abnormal with thickening

The ultrasound images above both portray fibularis (peroneus) longus tendons in their long axis (sagittal plane) as they cross the ankle joint. The tendon in the upper image (A) is notably thickened and an effusion can be seen adjacent to the bone. These signs suggest tendinopathy. The tendon in the image below (B) is normal appearing and there is no associated effusion.