Type II Accessory Navicular

I have been treating a patient who presented with persistant ankle oedema and pain that is predominantly aggravated by active dorsiflexion (especially when driving). The is no pain on passive dorsiflexion. Tenderness ond oedema are diffuse with no specific findings. She recently had a MRI which showed a symptomatic type II accessory navicular. Has anyone had any experience treating this conservatively, as the only treatment option I have been able to find so far is surgical fusion, and the patient would prefer to have surgery as a last resort.