A biomechanics study on ligamentous injury in anterior-posterior compression type II pelvic injury

Jianzhong Kong,Yu Xu,Chengwei Zhou,Guodong Bao,Xiaolong Shui,Xiaoshan Guo,Shuaibo Sun,Yupeng Chu

doi:10.1186/s13018-020-02156-w

Abstract

BackgroundAnterior-posterior compression (APC) type II pelvis fracture is caused by the destruction of pelvic ligaments. This study aims to explore ligaments injury in APC type II pelvic injury.MethodFourteen human cadaveric pelvis samples with sacrospinous ligament (SPL), sacrotuberous ligament (SBL), anterior sacroiliac ligament (ASL), and partial bone retaining unilaterally were acquired for this study. They were randomly divided into hemipelvis restricted and unrestricted groups. We recorded the separation distance of the pubic symphysis and anterior sacroiliac joint, external rotation angle, and force when ASL ruptured. We observed the external rotation damage to the pelvic bone and ligaments.ResultWhen ASL failed, there was no significant difference in pubic symphysis separation (28.6 ± 8.4 mm to 23.6 ± 8.2 mm, P = 0.11) and anterior sacroiliac joint separation (11.4 ± 3.8 mm to 9.7 ± 3.9 mm, P = 0.30) between restricted and unrestricted groups. The external rotation angle (33.9 ± 5.5° to 48.9 ± 5.2°, P < 0.01) and force (553.9 ± 82.6 N to 756.6 ± 41.4 N, P < 0.01) were significantly different. Pubic symphysis separation between two groups ranged from 14 to 40 mm. In the restricted group, both SBL and SPL were injured. SPL ruptured first, and then SBL and the interosseous sacroiliac ligament were damaged while the posterior ligament remained unharmed. In the unrestricted group, interosseous sacroiliac ligament and posterior sacroiliac ligaments were damaged, while SBL and SPL were not. When the ASL, SBL, and SPL all failed, pubic symphysis and anterior sacroiliac joint separation between two groups increased significantly (from 28.6 ± 8.4 to 42.0 ± 7.6 mm, 11.4 ± 3.8 to 16.7 ± 4.2 mm respectively, all P < 0.05).ConclusionPelvic external rotation injury is either hemipelvic restricted or unrestricted, which can result in different outcomes. When the ASL ruptures, the unrestricted group needs greater external rotation angle and force, without SBL or SPL injury, while both SBL and SPL were injured in another group. When ASL fails in two groups, pubic symphysis separation fluctuates considerably. Finally, when the ASL ruptures, SBL and SPL may be undamaged.

Highlights

Pelvic fractures occur frequently and can be complicated by multiple traumas [1,2,3]
sacrospinous ligaments (SPL) ruptured first, and sacrotuberous ligament (SBL) and the interosseous sacroiliac ligament were damaged while the posterior ligament remained unharmed
When the anterior sacroiliac ligament (ASL) ruptures, the unrestricted group needs greater external rotation angle and force, without SBL or SPL injury, while both SBL and SPL were injured in another group

Summary

Introduction

Pelvic fractures occur frequently and can be complicated by multiple traumas [1,2,3]. The anterior and posterior compression (APC) pelvic injury, a classic type known as external rotation injury, is considered to be caused by the destruction of pelvic ligaments. There have been some biomechanical articles about APC pelvic fracture treatment [7, 8]; there are few about ligamentous injury in APC pelvic fracture. Toward this end, we biomechanically modeled the pelvic external rotation injury (APC type II pelvis fracture) to explore pelvic ligamentous injury and the separation distance of the pubic symphysis and sacroiliac joint when anterior sacroiliac ligament (ASL) ruptured. Anterior-posterior compression (APC) type II pelvis fracture is caused by the destruction of pelvic ligaments. This study aims to explore ligaments injury in APC type II pelvic injury

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