The structural function of bone is to resist axial force and bending moments. Axial forces and bending moments are functions of time. Therefore, bone remodels to asymmetrical stress as a function of time. In other words, the amount of remodeling is proportional to the length of time the vertebrae are subjected to the abnormal load. A primary stress system dictates that the stress and bone material are parallel.
Collagen fibers run vertical in bone as does axial loading.
When abnormal translations and rotations are present in the spine the collagen fibers and axial loading are no longer parallel and a secondary stress system occurs . . . Therefore bone remodeling is necessary. The electrical values that are measured from bone under asymmetric stress, and the electrical values that are used to promote bony unions are within the same range of frequencies that cause electrical nerve interference. The electromagnetic fields that are produced in bone deformation are in the frequency range of 1-72 Hz. Electric nerve interference occurs between 0.5-75 Hz.