Sprained ankle. no fractures/dislocations in ankle on xr. ankle mri shows mild sprain of deltoid ligament & full-thickness anterior & interosseous syndesmotic ligaments & partial thickness tear of posterior syndesmotic lig. is ankle surgery needed?

Such a sprain of the ankle is as or more serious than some actual ankle fractures. To avoid ending up with chronic ankle problems for the rest of your life ( I've seen such patients) get an orthopedic surgeon with a special interest in complex ankle injuries to treat you. You may have to get one a the department of orthopedic surgery at a university hospital.