What causes piriformis syndrome. Could it cause pain in the whole leg and knee? Does it cause difficulty in stepping on foot. Please help?

Pyriformis syndrome. Pyriformis syndrome is pain in the buttocks cause by imbalance of the pyriformis muscle that crosses near the sciatic nerve that can cause sciatica just like a herniated disc. I have had this and there are some great online stretching exercises to help as well as to diagnose this condition. See your pcp and ask to see a good physical therapist who may help you sort things out.