Congenital
Achondroplasia
SED
Polynesians (trefoil)
Prematurity
Osteopetrosis
Acquired
Degenerative discs
Spondylolisthesis
Kyphosis
Trauma
Iatrogenic
- post laminectomy
Miscellaneous
- Paget's
- AS
- DISH
- Fluorosis
Tumour