When I had a herniated disk (before surgery), my PT tried mechanical traction. I let her do it once. I was in absolute agony afterwards. After a subsequent reherniation, I went to a different PT who did a manual traction, almost as part of a back massage. That I could tolerate just fine. I suppose manual traction does help some folks, but I wouldn't recommend doing it unless your orthopedic doc recommends it.

Kay