Table 1.
Redefining lumbosacral transitional vertebrae (LSTV) classification through integrating the full spectrum of morphological alterations in a biomechanical continuum.2
| Dysplastic L5 Transverse Process (TP)* | Type I A | Type I B | Type I A F (i/c) or Type I B F(i/c) | Type I A F2 or Type I B F2 | - | |
| Unilateral TP ≤ 19 mm in width* | Bilateral TPs ≤ 19 mm in width* | With presence of ipsi/contra lateral rudimentary facet to the side of the L5 enlargement | With presence of bilateral rudimentary facets | |||
| Accessory articulations | Type II A | Type II B | Type II A F(i/c) or Type I B F(i/c) | Type II A 2F or Type II B 2F | ||
| Unilateral L5-S1 accessory articulation | Bilateral L5-S1 accessory articulations | With presence of ipsi/contra lateral rudimentary facet to the side of the diarthrosis | With presence of bilateral rudimentary facets | - | ||
| Sacralisation** | Type II A | Type III B | Type III C | Type III A F (i/c) or Type III B F(i/c) or Type IIIC F | Type III A 2F or Type III B 2F or Type III C 2F | |
| Unilateral L5-S1 sacralisation | Unilateral complete sacralisation with contralateral L5-S1 pseudoarthrosis | Bilateral complete L5-S1 sacralisation | With presence of ipsi/contra lateral rudiemntary facet to the side of the sacralisation | With presence of bilateral rudimentary facets | ||
| Lumbarisation** | Type IV A | Type IV B | Type IV C | Type IV D | Type IV A F(i/c) or Type IV B F(i/c) or Type IV C F or Type IV D F | Type IV A 2F or Type IV B 2F or Type IV C 2F or Type IV D 2F |
| Incomplete/partial lumbarisation of S1 as an accessory S1-2 articulation | Unilateral complete separation of S1 from sacral mass | Bilateral S1-2 accessory articulation | Complete sacralisation with residual four segment sacrum | With presence of ipsi/contra lateral rudimentary facet to the side of the diarthrosis | With presence of bilateral rudimentary facets | |
*
Southworth and Bersack.29 Modifications on the Castellvi's classifications are given in bold and italics.
**
Situations with aymmetric augmentation of the auricular surface may be represented by adding the alphebets SR+ or SL+ for the corresponding right or the left sides.