Such as:
-Spinal mechanical instability, related to ligaments laxity and connective tissue disease like in rheumatoid arthritis, Down syndrome, Ehlar Danlos syndrome
-Severe degenerative instability, related to degenerative arthritis of the facet joint, like degenerative spondylolithesis.
-Rheumatic disease of the spine which may cause erosion of the soft tissue and ligaments causing mechanical instability, like rheumatoid arthritis.
-Previous trauma, infection or tumour which may affect the spinal stability.