Effect of lordosis angle change after lumbar/lumbosacral fusion on sacrum angular displacement: a finite element study

• DOI: 10.1007/s00586-014-3569-3
• Publication Date: 2014-09-17T12:59:56Z
• Authors: Ningfang Mao; Jian Shi; Dawei He; Yang Xie; Yushu Bai; Xianzhao Wei; Zhicai Shi; Ming Li
• Keywords: Lumbosacral joint; Lumbar lordosis

To assess and characterize the sacrum angular displacements in response to lumbar lordosis after lumbar/lumbosacral fusion.A finite element model of the lower lumbar spine-pelvis was established and used to simulate the posterior fusion at L3-L5 and L4-S1. The lordosis angle in the fusion segments was set to five different conditions with respect to the intact model: 10° less than intact, 5° less than intact, same as intact, 5° more than intact, and 10° more than intact. Variations of the sacrum angular displacements with lordosis changes were analyzed under loading setting of axial compression, flexion, extension, lateral bending, and axial rotation.Compared with the intact lordosis, both increased and decreased lumbar lordosis angles caused the sacrum angular displacements to be increased. The lordosis angle increased by 10° induced the most substantial increase in sacrum angular displacements. In addition, the sacrum angular displacements of the L4-S1 fusion model at different lordosis angles were higher than those of the L3-L5 fusion model.The sacrum angular displacements occur as a result of the fusion surgery (L4-S1) and the changes in lumbar lordosis.