Lumbosacral transitional anatomy types and disc degenerative changes

Abstract

Background and purpose: The relationship between presence of lumbosacral transitional vertebra (LSTV) and disc degenerative changes is unclear. The aim of the study was to examine the relation between different types of LSTV and disc degenerative changes at the transitional and the adjacent cephalad segment. Material and methods: Sixty-three patients (mean age 51.48 ± 13.51) out of200 adults with low back pain who performed MRI examination of the lumbosacral spine, classified as positive for LSTV, were included in the study. Annular tears, disc degeneration according to Phirmann classification and disc herniations were evaluated and graded at transitional and adjacent cephalad level. Results: The severity of disc degeneration at the transitional level and the adjacent level correlated with the types of LSTV. Severe disc degenerative changes were most frequent in articulated connection LSTV types and in combined LSTV type at the transitional level and in osseus connection LSTV types at the adjacent cephalad level. These changes were more frequent in unilateral articulated connection LSTV subtype (64% vs 54%); and in unilateral osseus connection LSTV subtype (25% vs no patients) at transitional level, and in bilateral osseus connection LSTV subtype (100% vs 50%) at the level above. High prevalence of disc herniations was observed in articulated connection LSTV types as well as in unilateral osseus connection LSTV subtype at transitional and the adjacent cephalad level. At the transitional level higher prevalence of disc herniations was characteristic for unilateral articulated connection LSTV subtype (46%vs 41%) and for unilateral osseus connection LSTV subtype (50% vs no patients). At the adjacent level higher prevalence of disc herniations was observed in bilateral articulated connection LSTV subtype (38% vs 27%) and in bilateral osseus connection LSTV subtype (50% vs 25%). Conclusions: The compact osseus connection (osseus bridging vs articular bridging) of the lumbosacral transitional vertebra with the sacrum protects the disc at the transitional level and produces greater stress to adjacent cephalad segment. Bilateral osseus bridging seems to be most protective to the disc at the transitional level, but this type of LSTV produces great stress to the adjacent cephalad level.