I had my knees replaced four weeks ago and have had some trouble with lower back pain. Is this a common by product of bilateral replacement rehab? I otherwise can't complain - I am wallking almost normally (hurts a little still) and can see the operation was probably a success. A different question: Why is the area above the knee so very painful? Everyone I talk to has said the same thing, that that area is way sore for a long time after surgery.