I have a client who had his neck fused together at a young age from an injury. This client's chiropractor sent him to me 6 years ago to see if I could help him with the stiff muscles. I contacted my client's chiropractor to ask several questions about stretching my client with out causing any more damage or possibly "breaking" this man's neck. The chiropractor said, NO, you can't do any damage by stretching him, go for it! I have done research on how to stretch the client's neck and manipulate the muscles to where he can get relief instantly. The client come to me each week for a 30 minute session and is very happy with my work and says he can't live without the massages. The range of motion he receives is awesome!
If you need a reference my client said he would be glad to help!