Instability of the lumbo sacral junction can lead to pressure on the nerve roots or cauda equina. This can cause causing degrees of neurological signs including pain, ataxia, paresis or paralysis.
Stabilisation is traditionally done with pins and PMM cement which is bulky, can’t be adjusted and often fractures with time.
Pedicle screws are used extensively in humans. These are now available for veterinary use.
Thanks to Dan Ogden for the picture.