The Castellvi classification for LSTV
| Classification | Laterality | Description |
|---|---|---|
| I | Unilateral (a) Bilateral (b) | Dysplastic transverse process with a ≥19-mm width on the craniocaudal dimension |
| II | Lumbarization or sacralization with an enlarged transverse process that has a diarthrodial joint with the sacrum | |
| III | Lumbarization or sacralization with complete osseous fusion of the transverse process to the sacrum | |
| IV | – | Unilateral IIa transition with a IIIa transition on the contralateral side |
Note:—The en dash indicates duplicate entries.