Oedematous thickening of the tibialis anterior tendon sheath consistent with tenosynovitis with less prominent tenosynovitis of extensor hallucis longus. There is oedema centered over the inferior extensor retinaculum.
Additional findings include a talanavicular ganglion which encroaches upon the sinus tarsi as well as the anterior tarsal tunnel in proximity to the deep peroneal nerve. Clinical assessment would be required to exclude anterior tarsal tunnel syndrome, however tibialis anterior tenosynovitis is enough of a cause for pain in this patient. The is also focal synovitis / scarring adjacent to the posterior talofibular ligament which could be a sign of posterolateral impingement or prior injury. No evidence of navicular stress fracture or reaction.