Methods for improving spinal alignment and motion

A surgical method for creating a desired lordosis or kyphosis between a first upper vertebrae and a second lower vertebrae, comprising:

• removing at least a portion of a natural intervertebral disc from between the upper and lower vertebrae to create a disc space, wherein an endplate of the lower vertebra has a generally planar natural endplate surface;
• removing a first wedge of bony material from the lower vertebra to create a first modified vertebral surface which is non-parallel to the generally planar natural endplate surface, at least a first portion of the first modified vertebral surface cutting completely through a posterior cortical bone surface of the endplate and a posterior cortical ring of the lower vertebra without completely removing an anterior cortical bone surface of the endplate of the lower vertebra;
• removing at least a portion of a natural pedicle of the lower vertebrae to create a first modified pedicle surface which extends along a remaining portion of the natural pedicle;
• inserting a lower portion of a first arthroplasty device at least partially into the disc space, the lower portion of the first arthroplasty device including an upward facing articulation surface, a first lower surface adapted to engage with the first modified vertebral surface and a bridge portion having a first surface for engaging with the first modified pedicle surface outside of the disc space;
• and
• attaching the first arthroplasty device to the lower vertebrae with a bone fastener.