I had the same thing, spacing was fine laterally, but front and back spacing was a little off.
Usually they want to try therapy before going to surgery anyways.
Just show him that you are generally concerned and that you think therapy won't help.
1. Get an MRI
2. Get Stress x-rays (where they pressure and bend your ankle to check spacing laterally and front to back)
3. After those are done, he can see if you need surgery