In 1999, at age 37, I suffered a SEVERE knee injury on a job site, (Fayette County Detention Center construction), thanks to one of the laborers. Basically, three different surgeons stated it was the single worst knee injury they had ever seen; everything was torn. Bone chips the size of nickels were floating in the subsequent swelling. Each said I would have been better off had my lower leg bones snapped. Several surgeries later, they finally gave up and gave me a total knee replacement. The first few weeks post surgery are nothing short of hell, just unreal pain. Now, the same knee needs replaced again, and my "good" knee now needs it as well due to favoring it so much over the years.
When I finally cave in, I'm going to go ahead and have them both done at the same time, no way am I going through that pain again twice, lol.
Best of luck OP, and if the doctor tells you to go to therapy....go to therapy. It will hurt like the devil, but in the long run it's well worth it.