Scientific basis for the treatment of low back pain.

Disc degeneration causes back pain because the function of the disc as a load transferring structure is abnormal, producing abnormal patterns of load which cause pain. Fusion has been unpredictable because it only fortuitously addresses loading. A fusion may be in such a position that it takes load from the disc, and this may be reflected in the way the fusion models, demonstrating a weight bearing pattern, but this is unpredictable. Recognition that we are dealing with a problem of load transfer allows us to design any surgical implant to solve this problem, without stopping movement.