Bone spurs are an enlargement of the normal bony structures of the spine. As spinal disc material wears down, ligaments loosen and excess motion occurs at the joint. This leads to a thickening of the ligaments that hold the bones together. Over time, these thickened ligaments tend to calcify, which leads to bone spur formation.
Some mistakenly think that bone spurs are somehow interfering with the normal spinal anatomy and causing pain. In fact, bone spurs form over a long period of time, and are simply an indication that there is degeneration of the spine.
Certain things can accelerate bone spur growth: heredity, nutrition, lifestyle (posture), and accidents. The medical term for bone spurs is osteophytes.