The remarkable thing about the SPORT study was that even after patients agreed to participate in the study and be randomized to either surgery or conservative treatment, they left the group they were assigned to in large numbers.

Those assigned to conservative treatment, if they felt their pain was unbearable, switched to surgery, and those in the surgery group, feeling they could tolerate their pain, switched to conservative treatment.

So in the end, while both groups did the same--people tended to heal well from disk-caused sciatica--the study ended up showing that people in severe pain, choosing surgery, do well; and people in less pain, choosing to avoid surgery, do well.

That people refused to stay randomized based on their pain was interesting, in itself. It mimicked life more than the researchers expected.