Sacroiliac joint stability: Finite element analysis of implant number, orientation, and superior implant length

Table 4 Change in sacroiliac joint flexion-extension range of motion (°) as a result of reducing the number of implants

Treatment	Implants (positions)	Superior implant ending point	Range of motion (°)	Motion increase (°)	% 3 Implant motion
Intact	-	-1	1.94	-	-
Inline	3 (S, M, I)	Mid-ala	0.7	Reference configuration
Inline	2 (S, M, -)	Mid-ala	0.97	0.27	39
Inline	2 (S, -, I)	Mid-ala	0.82	0.12	17
Inline	2 (-, M, I)	-1	0.91	0.21	30
Inline	1 (S, -, -)	Mid-ala	1.36	0.66	94
Inline	1 (-, M, -)	-1	1.32	0.62	89
Inline	1 (-, -, I)	-1	1.25	0.55	79
Inline	3 (S, M, I)	Mid-sacrum	0.63	Reference configuration
Inline	2 (S, M, -)	Mid-sacrum	0.76	0.13	21
Inline	2 (S, -, I)	Mid-sacrum	0.69	0.06	10
Inline	1 (S, -, -)	Mid-sacrum	1.21	0.58	92
Transarticular	3 (S, M, I)	Mid-ala	0.59	Reference configuration
Transarticular	2 (S, M, -)	Mid-ala	0.81	0.22	37
Transarticular	2 (S, -, I)	Mid-ala	0.69	0.1	17
Transarticular	2 (-, M, I)	-1	0.76	0.17	29
Transarticular	1 (S, -, -)	Mid-ala	1.36	0.77	131
Transarticular	1 (-, M, -)	-1	1.11	0.52	88
Transarticular	1 (-, -, I)	-1	1.05	0.46	78
Transarticular	3 (S, M, I)	Mid-sacrum	0.52	Reference configuration
Transarticular	2 (S, M, -)	Mid-sacrum	0.64	0.12	23
Transarticular	2 (S, -, I)	Mid-sacrum	0.58	0.06	12
Transarticular	1 (S, -, -)	Mid-sacrum	1.21	0.69	133
Treatment	Implants (positions)	Superior implant ending point	% 3 Implant motion	Implants (positions)	Median (%) [range]
Inline	2 (S, -, I)	Mid-ala	17	2 (S, -, I)	14.5% (10-17)
Inline	2 (S, -, I)	Mid-sacrum	10
Transarticular	2 (S, -, I)	Mid-ala	17
Transarticular	2 (S, -, I)	Mid-sacrum	12
Inline	2 (S, M, -)	Mid-ala	39	2 (S, M, -)	30% (21-39)
Inline	2 (S, M, -)	Mid-sacrum	21
Transarticular	2 (S, M, -)	Mid-ala	37
Transarticular	2 (S, M, -)	Mid-sacrum	23
Inline	2 (-, M, I)	-1	30	2 (-, M, I)	29.5% (29-30)
Transarticular	2 (-, M, I)	-1	29
Inline	1 (S, -, -)	Mid-ala	94	1 (S, -, -)	112.5% (92-133)
Inline	1 (S, -, -)	Mid-sacrum	92
Transarticular	1 (S, -, -)	Mid-ala	131
Transarticular	1 (S, -, -)	Mid-sacrum	133
Inline	1 (-, M, -)	-1	89	1 (-, M, -)	88.5% (88-89)
Transarticular	1 (-, M, -)	-1	88
Inline	1 (-, -, I)	-1	79	1 (-, -, I)	78.5% (78-79)
Transarticular	1 (-, -, I)	-1	78

¹Configuration does not include a superior implant. S: Superior; M: Middle; I: Inferior.