While most people have only five lumbar vertebrae, there are cases where someone could have an extra lumbar vertebra. This is called lumbarization. It is usually the result of the first and second parts of the sacrum failing to fuse, creating an extra bone in the spinal column.

In the majority of cases, this condition is harmless. However, some people who live with lumbarization may experience lower back pain without knowing why or may be more prone to herniated discs in their spine.