This patient most likely has Achilles tendinopathy, which classically presents with burning heel pain and stiffness that worsen with activity and improve with rest. As there is no inflammation seen on histopathologic examination, use of the term tendinopathy is preferred to tendinitis. On examination, there is frequently tenderness to palpation approximately 2 to 6 cm proximal to the Achilles tendon insertion on the calcaneus. Symptoms typically begin after an individual increases his or her level of physical activity, as is the case with this patient.

This patient has no evidence of Achilles tendon rupture, which usually but not always presents with the sudden onset of heel pain while the patient is participating in a strenuous activity. Patients may also report hearing a popping sound. On examination, a palpable Achilles tendon defect may be present, and there is usually a positive Thompson test.

High ankle sprains typically result from excessive dorsiflexion or eversion that causes injury to the tibiofibular syndesmotic ligaments connecting the distal tibia and fibula. Unlike in this patient, pain is typically elicited by medial-lateral compression of the leg at the mid-calf level (squeeze test) or by having the patient cross his legs with the mid-calf of the painful leg resting on the other knee (crossed-leg test).

Tarsal tunnel syndrome is caused by compression of the posterior tibial nerve as it passes within the tarsal tunnel below the medial malleolus. It is characterized by pain and paresthesias in the medial ankle that extend into the midfoot. Symptoms commonly worsen with standing, walking, and running. On examination, pain can be elicited by tapping on the posterior tibial nerve along its course.