Approach-related anatomical differences in patients with lumbo-sacral transitional vertebrae undergoing lumbar fusion surgery at level L4/5

Anterior spinal fusion (ALIF/OLIF/LLIF) with lumbosacral transitional vertebra: A systematic review and proposed treatment algorithm

•Key anterior approaches differences in LSTV include vascular (aortic bifurcation/iliocaval confluence), muscular (psoas) and osseus anatomy (inter-crestal tangent/pubic symphysis), when compared to non-LSTV.•There are increased surgical deviations but not significantly greater complications for anterior approaches in LSTV.•Vascular awareness while accessing L45 will be in the presence of a more cephalad ABF and ICC with sacralized L5, and access to the deeper L56 level will be in the presence of a more caudal ABF and ICC in lumbarized S1.

Lumbosacral Transitional Vertebrae Influence on Acetabular Orientation and Pelvic Tilt

Lumbosacral transitional vertebrae (LSTV) are common congenital variances with a prevalence found in the population up to 35.6%. The literature demonstrates an influence of LSTV on bony pelvic anatomy. The influence on the anatomical acetabular orientation, which is important for cup positioning in total hip arthroplasty, has not yet been described for patients with LSTV. A total of 53 patients with LSTV were identified from a CT Database including 819 subjects. Fifty patients with LSTV could be included and were matched for age and sex against a control group. We examined the influence of LSTV, classified according to Castellvi, on acetabular orientation and pelvic tilt in the supine position. Functional acetabular anteversion and inclination, assessed against the table plane, were compared against anatomical acetabular anteversion and inclination, assessed against the anterior pelvic plane. The anatomical acetabular inclination correlated with the pelvic tilt (r = 0.363, p < 0.001). The anatomical acetabular inclination was significantly larger than the functional acetabular inclination in the supine position (p < 0.001). Castellvi grading of LSTV correlated negatively with pelvic tilt (ρ = −0.387, p = 0.006). Castellvi grading correlated significantly with functional acetabular anteversion (ρ = 0.324, p = 0.022) and anatomical acetabular anteversion (ρ = 0.306, p = 0.022). A higher Castellvi grading was accompanied by a reduced pelvic tilt in the supine position. The functional acetabular anteversion and anatomical acetabular anteversion increased in parallel to the higher Castellvi grading. Therefore, LSTV and Castellvi grading might be assessed on pre-operative X-rays prior to hip arthroplasty and surgeons might consider adjusting cup positioning accordingly.