I had a fusion of the L-4 Thru S-1 about 10yrs agon. I had a recent fall backwards while pulling on a release handle on my semi trailer. The numbness radiates from the top of the front leg down to just below the knee. It feels like I have a knee pad on when I kneel. I also get a sharp pain in the knee especially on the inside of it. I have seen a neuro and have had a MRI done. One doctor says I have a herniated L-3 L-4 disc with narrowing of the spinal column. The 2nd doctor who also teaches says he sees no narrowing or herniated disc and did not address the numbness. When I walk more than 10 to 12 minutes, my legs become very weak and I increase the pain along the lower back and up the spinal column about 3/4 way up.