Settlement amount that is fair after injured on the job?

i injured my right knee last march at work and had to have surgery to replace my ACL and repair my meniscus. i had not gained full function of my knee when i had to have a second surgery to remove scar tissue and was supposed to repair another tear in my meniscus but it was not repaired. was told it will heal. i am still not full functioning but was released to go back to work light duty. i am in constant pain. what is a fair amount i should ask for my attorney to requeast from workers comp? i live in missouri.