What's the noun for lumbal? Here's the word you're looking for.
lumbarization
A spinalanomaly in which the first and second segments of the sacrum do not fuse, and consequently the lumbar spine appears to have six vertebrae or segments, not five, while the sacrum appears to have only four.
lumbago
(pathology)Backache of the lumbar region or lower back, which can be caused by muscle strain or a slipped disk.