If this is post surgery injury then I will require a sign off letter from your PT and a list of do's and dont's that you can do in a yoga practice.
If you are seeing a PT for a non surgical injury, please check with your PT as to what you are able to do. A lot of times I can incorporate your PT exercise program into a home yoga practice. However, it is the students responsibility to check with their PT or Certified Health Care Practitioner before starting any exercise program.
This answer is really based upon individual circumstances, and the reason you are working with a provider for your symptoms of PTSD. It's impossible for me to answer this question in such a broad sense, as students can suffer from PTSD for multiple reasons, and be at different levels of their treatment, and have many different triggers. Talking with your mental health practitioner and directing them to the iRest website is a good starting point, as they will be able to determine whether this would be a good fit for you. iRest is another tool in our coping mechanism.
This is a great question, and something I've experienced with a few of clients. The clients were dealing with grief but were not ready to go to a provider, they just wanted a space where they could just be with whatever was coming up. I provided the ideal space and time, and after about 6 sessions of iRest Yoga Nidra, the clients were ready to see a mental health provider where they could seek more specialized help and treatment for what they were dealing with.