Kyphosis in the paralytic spine.

The paralytic spine without supplementary support is unstable and susceptible to axial collapse. The biomechanical factors responsible for spinal stability should be considered in any treatment regimen for paralytic spines. If posterior fusion is elected as the treatment, kyphosis must be corrected so that the eccentric loading and kyphotic bending moment is very small. When this is done, posterior fusion alone is adequate to give spinal stability and increased function to the individual.