While once again browsing the topic of ACL reconstruction, I managed to find an article about ligament healing called "prolotherapy." Apparently it is not a common form of therapy used to treat chronic pain, but its nonethless interesting. Granted you have to have a ligament before prolotherapy is undertaken, it's a relatively unheard of treatment, so far as the article mentions.
http://www.diagnose-me.com/treat/T85233.html