Manipulation is as effective as everything else that a medical doctor has to offer to treat low-back pain, yet many doctors criticize osteopaths and chiropractors for using manipulation.
I remember a lead article in the New England Journal of Medicine (11/99) which showed that spinal manipulation is at least as effective in controlling low-back pain as the standard medical treatments of ultrasound, antiinflammatory drugs, anti-pain drugs, diathermy heat treatments, hot or cold packs, use of a corset or transcutaneous nerve stimulation. I have always recommended deep massage and manipulation for low back pain, for pain relief, not as a cure. When I had a persistant back problem, I chose deep massage of my back and was able to return to riding my bike in just six weeks.
Many medical doctors recommend cortisone injections when the evidence is that the most they can offer is temporary pain relief. It is not a cure. Surgery is specific for a limited number of cases of low-back pain and has a high failure rate. The NEJM article reinforced my experience that deep massage and manipulation can help to relieve some cases of severe low-back pain.