Trabecular and cortical bone architecture in the sacrum demonstrate the pattern of load-transmission through the bone. Transitional vertebrae at the lumbo-sacral junction present either with fusions between the L5 vertebrae and the first sacral segments or as accessory articulations between the transverse processes of L5 and the alae of the sacra. These morphological changes are associated with alterations in load-transmission patterns in the region and with low back pain situations. This study analyses the trabecular pattern in sacra bearing fused L5 vertebrae as well as those with unilateral articulation with L5 transverse element. The study reveals that: a) in complete sacralisation, the level of the auricular surfaces extend between the lower aspect of the L5 and the S2 segments with incorporation of the L5 into the load-bearing segments of the sacrum; b) The trabecular patterns are discrete and conspicuous in the L5, S1 and S2 segments and show prominent ventral and dorsal trabecular areas with an intervening area of reduced density; and c) The sacra with accessory L5 articulation demonstrate auricular surfaces situated at a relatively higher level with the upper two sacral segments bearing prominent trabecular as well as cortical bones on the side of the accessory articulation. The S3 segment bears less load and presents with rarified trabecular and cortical bone in transitional states with L5-S1 accessory articulation.