Table 1.

Castellvi classification of transitional lumbosacral vertebra (TLV)

Castellvi classification	TLV transverse process morphology
Type I	Elongated (Type Ia) unilateral (Type Ib) bilateral
Type II	Pseudo-articulating (Type IIa) unilateral (Type IIb) bilateral
Type III	Fused (Type IIa) unilateral (Type IIb) bilateral
Type IV	Combined – Type IIa and Type IIIa (one pseudo-articulating and one fused)