Three-dimensional finite element analysis with different internal fixation methods through the anterior approach

Table 1 Material property parameters of the main structures of the pelvis

Part	Modulus of elasticity in MPa	Poisson’s ratio
Pubic cartilage	5.00	0.45
Interosseous sacroiliac ligament	5610.00	0.20
Sacrum	6140.00	0.30
Sacrospinous ligament	12.60	0.20
Sacrotuberous ligament	46.48	0.300
Sacroiliac joint cartilage	54.00	0.40
Iliac cancellous bone	132.00	0.20
Femur	18200.00	0.38
Posterior sacroiliac ligament	133.00	0.20
Acetabular cartilage	12.00	0.42
Iliac cortical bone	17000.00	0.30
Anterior sacroiliac ligament	208.00	0.20

Table 2 The stress of each point on the fracture line, in MPa

Node	Combined steel plate		Internal iliac plate		Row nail blocking		Triangular steel plate		Spring steel plate
	Sitting	Standing	Sitting	Standing	Sitting	Standing	Sitting	Standing	Sitting	Standing
1	0.470	0.891	0.549	0.703	0.606	0.827	0.485	0.568	0.538	0.650
2	0.812	0.299	0.991	0.376	1.200	0.239	1.227	0.412	1.142	0.483
3	1.285	0.653	1.213	0.792	1.197	1.105	1.298	0.923	1.186	0.792
4	2.296	0.603	1.929	0.624	2.314	0.612	2.305	0.706	2.401	0.654
5	2.017	1.880	2.117	1.597	2.153	2.683	2.129	2.507	2.113	2.019
6	2.664	1.751	2.653	1.815	2.726	1.920	2.803	1.192	2.735	1.803
7	0.535	0.154	0.509	0.173	0.541	0.187	0.551	0.180	0.547	0.161
8	0.592	1.153	0.603	1.128	0.614	1.164	0.597	1.226	0.602	1.092
9	0.783	1.228	0.790	1.316	0.793	1.357	0.785	1.366	0.798	1.124
10	0.947	0.776	0.938	0.839	0.951	0.914	0.963	0.814	0.971	0.785
Mean	1.240	0.939	1.229	0.936	1.310	1.101	1.314	0.989	1.303	0.956
SD	0.757	0.541	0.708	0.497	0.756	0.719	0.778	0.618	0.772	0.547
Minimum value	0.470	0.154	0.509	0.173	0.541	0.187	0.485	0.180	0.538	0.161
Maximum value	2.296	1.880	2.653	1.815	2.726	2.683	2.803	2.507	2.735	2.019

In the sitting position, there were no statistical differences among groups (P = 0.979). In the standing position, there were no statistical differences among groups (P = 0.974). SD: Standard deviation.

Table 3 Displacement of each point on the fracture line, in mm

Node	Combined steel plate		Internal iliac plate		Row nail blocking		Triangular steel plate		Spring steel plate
	Sitting	Standing	Sitting	Standing	Sitting	Standing	Sitting	Standing	Sitting	Standing
1	0.097	0.089	0.085	0.099	0.087	0．103	0.093	0.107	0.102	0.141
2	0.910	0.103	0.481	0.086	0.956	0.097	0.914	0.105	1.104	0.127
3	0.938	0.112	0.458	0.102	0.683	0.124	0.832	0.120	1.017	0.136
4	0.104	0.093	0.484	0.128	1.109	0.115	0.753	0.098	0.936	0.128
5	0.887	0.121	0.401	0.157	0.990	0.131	0.914	0.144	1.125	0.205
6	0.682	0.117	0.377	0.128	0.887	0.135	0.756	0.126	0.913	0.146
7	0.652	0.129	0.473	0.172	0.633	0.153	0.671	0.167	0.801	0.182
8	0.556	0.194	0.503	0.172	0.545	0.201	0.539	0.187	0.714	0.214
9	0.520	0.198	0.588	0.171	0.511	0.198	0.597	0.178	0.618	0.201
10	0.690	0.239	0.590	0.241	0.538	0.244	0.702	0.237	0.843	0.257
Mean	0.604	0.140	0.444	0.146	0.694	0.150	0.677	0.147	0.817	0.171
SD	0.286	0.049	0.136	0.044	0.286	0.046	0.227	0.042	0.283	0.042
Minimum value	0.097	0.089	0.085	0.086	0.087	0.097	0.093	0.098	0.102	0.127
Maximum value	0.938	0.240	0.590	0.241	1.109	0.244	0.914	0.237	1.125	0.257

In the sitting position, there was a statistical difference in the means among groups (P = 0.004). The pairwise comparisons indicated that the average displacement of the internal iliac plate group was significantly smaller than that of the spring plate group (P = 0.002). There were no other significant pairwise differences (all P > 0.05). In the standing position, there were no significant differences in the means among groups (P = 0.299). SD: Standard deviation.