hi!!
@alophysio: seems that i follow you everywhere. i would suggest that we have the same fields of interest :-))
And i still agree with alophysio. the talus mainly consists of kind of cartilagnous bone and as a result it heals very badly when fractured. thus, necrosis happens as a result of less blood supply in this area. so surgery and a kind of reconstruction af the necrotic area might be indicated. also immobilisation seems to be necessary. but first of all check pros and cons of surgery etc. are you able to do all adls properly? what about sport/exercise? maybe you can try it first with rehab, lots of stability exercises for ankle and knee joint and strenghening of the surrounding muscles.
good luck!!