Where is the most appropriate application site for ultrasound treatment of peroneus longus and brevis tendons?

The most appropriate application site for ultrasound treatment of the peroneus longus and brevis tendons is posterior to the lateral malleolus. This is because the peroneus longus and brevis tendons run along the lateral aspect of the lower leg and ankle. Specifically, they pass behind the lateral malleolus, which provides optimal access to these tendons.

By positioning the ultrasound transducer in this area, the treatment can effectively target the tendons' site of injury or dysfunction, allowing for improved healing and symptom relief. The use of ultrasound in this area can help decrease inflammation, improve blood flow, and promote tissue repair.

The other application sites provided are less suitable for targeting these specific tendons. The sustentaculum tali and sinus tarsi do not directly correlate with the locations of the peroneus longus and brevis tendons, as they involve anatomical structures that are not related to these tendons. Similarly, the anterior aspect of the lateral malleolus does not provide proper access to the tendons in question, making it a less effective choice for ultrasound application. Thus, the posterior location is the optimal site for treatment.