They say that the entire body is connected, and it really is true in terms of knee and back pain. So many people that suffer from lower back pain end up with knee problems, as they limp, walk gingerly, or just sit wrong to avoid hurting their back. That uneven strain on the knees wears away at the cartilage unevenly, and you can end up with the strangest knee pains all thanks to the back pain.
Also, lower back pain can often lead to tight hamstring muscles, which causes another type of strain on the knees. The two are so closely linked, so it's essential to take care of your back.