Basic Study
Copyright ©The Author(s) 2018.
World J Orthop. Mar 18, 2018; 9(3): 14-23
Published online Mar 18, 2018. doi: 10.5312/wjo.v9.i3.14
Table 1 Sacroiliac joint range of motion for an intact model and 22 configurations of implant orientation, superior implant length, and number of implants
Treatment/orientationImplant placed
Superior implant ending pointSI joint ROM (°) [Reduction in ROM (%)]
SuperiorMiddleInferiorFlexion-extensionLateral bendingAxial rotation
Intact----11.94° (-)0.66° (-)1.11° (-)
Inline orientationXXXMid-ala0.7° (64%)0.45° (32%)0.41° (63%)
Mid-sacrum0.63° (68%)0.41° (38%)0.38° (66%)
X-XMid-ala0.82° (58%)0.47° (29%)0.44° (60%)
Mid-sacrum0.69° (64%)0.43° (35%)0.4° (64%)
XX-Mid-ala0.97° (50%)0.5° (24%)0.49° (56%)
Mid-sacrum0.76° (61%)0.45° (32%)0.43° (61%)
-XX-10.91° (53%)0.53° (20%)0.55° (50%)
X--Mid-ala1.36° (30%)0.58° (12%)0.67° (40%)
Mid-sacrum1.21° (38%)0.58° (12%)0.61° (45%)
-X--11.32° (32%)0.65° (2%)0.73° (34%)
--X-11.25° (36%)0.69° (-5%)0.79° (29%)
Transarticular orientationXXXMid-ala0.59° (70%)0.41° (38%)0.34° (69%)
Mid-sacrum0.52° (73%)0.38° (42%)0.31° (72%)
X-XMid-ala0.69° (64%)0.42° (36%)0.36° (68%)
Mid-sacrum0.58° (70%)0.39° (41%)0.32° (71%)
XX-Mid-ala0.81° (58%)0.45° (32%)0.4° (64%)
Mid-sacrum0.64° (67%)0.41° (38%)0.35° (68%)
-XX-10.76° (61%)0.47° (29%)0.46° (59%)
X--Mid-ala1.36° (30%)0.58° (12%)0.67° (40%)
Mid-sacrum1.21° (38%)0.58° (12%)0.61° (45%)
-X--11.11° (43%)0.6° (9%)0.7° (37%)
--X-11.05° (46%)0.62° (6%)0.73° (34%)
Table 2 Reduction in sacroiliac joint range of motion (°) between transarticular and inline orientation groups
OrientationImplants (positions)Superior implant ending pointReduction in SI joint ROM (°) (%)
Flexion-extensionLateral bendingAxial rotation
Transarticular vs inline3 (S, M, I)Mid-ala0.11° (16%)0.04° (9%)0.07° (17%)
Mid-sacrum0.11° (17%)0.03° (7%)0.07° (18%)
2 (S, -, I)Mid-ala0.13° (16%)0.05° (11%)0.08° (18%)
Mid-sacrum0.11° (16%)0.04° (9%)0.08° (20%)
2 (S, M, -)Mid-ala0.16° (16%)0.05° (10%)0.09° (18%)
Mid-sacrum0.12° (16%)0.04° (9%)0.08° (19%)
2 (-, M, I)-10.15° (16%)0.06° (11%)0.09° (16%)
1 (-, M, -)-10.21° (16%)0.05° (8%)0.03° (4%)
1 (-, -, I)-10.20° (16%)0.07° (10%)0.06° (8%)
Median (°) (Range)0.13° (0.11-0.21)0.05° (0.03-0.07)0.08° (0.03-0.09)
Median (%) (Range)16% (16-17)9% (7-11)18% (4-20)
Table 3 Reduction in sacroiliac joint range of motion (°) between mid-sacrum and mid-ala placement groups
Reduction in SI joint ROM (°) (%)
Superior implant ending pointOrientationImplants (position)Flexion-extensionLateral bendingAxial rotation
Mid-sacrum vs mid-alaInline3 (S, M, I)0.07° (10%)0.04° (9%)0.03° (7%)
2 (S, -, I)0.13° (16%)0.04° (9%)0.04° (9%)
2 (S, M, -)0.21° (22%)0.05° (10%)0.06° (12%)
1 (S, -, -)0.15° (11%)0.00° (0%)0.06° (9%)
Trans-articular3 (S, M, I)0.07° (12%)0.03° (7%)0.03° (9%)
2 (S, -, I)0.11° (16%)0.03° (7%)0.04° (11%)
2 (S, M, -)0.17° (21%)0.04° (9%)0.05° (13%)
1 (S, -, -)0.15° (11%)0.00° (0%)0.06° (9%)
Median (°) (Range)0.14° (0.07-0.21)0.035° (0.00-0.05)0.045° (0.03-0.06)
Median (%) (Range)14% (10-22)8% (0-10)9% (7-13)
Table 4 Change in sacroiliac joint flexion-extension range of motion (°) as a result of reducing the number of implants
TreatmentImplants (positions)Superior implant ending pointRange of motion (°)Motion increase (°)% 3 Implant motion
Intact--11.94--
Inline3 (S, M, I)Mid-ala0.7Reference configuration
Inline2 (S, M, -)Mid-ala0.970.2739
Inline2 (S, -, I)Mid-ala0.820.1217
Inline2 (-, M, I)-10.910.2130
Inline1 (S, -, -)Mid-ala1.360.6694
Inline1 (-, M, -)-11.320.6289
Inline1 (-, -, I)-11.250.5579
Inline3 (S, M, I)Mid-sacrum0.63Reference configuration
Inline2 (S, M, -)Mid-sacrum0.760.1321
Inline2 (S, -, I)Mid-sacrum0.690.0610
Inline1 (S, -, -)Mid-sacrum1.210.5892
Transarticular3 (S, M, I)Mid-ala0.59Reference configuration
Transarticular2 (S, M, -)Mid-ala0.810.2237
Transarticular2 (S, -, I)Mid-ala0.690.117
Transarticular2 (-, M, I)-10.760.1729
Transarticular1 (S, -, -)Mid-ala1.360.77131
Transarticular1 (-, M, -)-11.110.5288
Transarticular1 (-, -, I)-11.050.4678
Transarticular3 (S, M, I)Mid-sacrum0.52Reference configuration
Transarticular2 (S, M, -)Mid-sacrum0.640.1223
Transarticular2 (S, -, I)Mid-sacrum0.580.0612
Transarticular1 (S, -, -)Mid-sacrum1.210.69133
TreatmentImplants (positions)Superior implant ending point% 3 Implant motionImplants (positions)Median (%) [range]
Inline2 (S, -, I)Mid-ala172 (S, -, I)14.5% (10-17)
Inline2 (S, -, I)Mid-sacrum10
Transarticular2 (S, -, I)Mid-ala17
Transarticular2 (S, -, I)Mid-sacrum12
Inline2 (S, M, -)Mid-ala392 (S, M, -)30% (21-39)
Inline2 (S, M, -)Mid-sacrum21
Transarticular2 (S, M, -)Mid-ala37
Transarticular2 (S, M, -)Mid-sacrum23
Inline2 (-, M, I)-1302 (-, M, I)29.5% (29-30)
Transarticular2 (-, M, I)-129
Inline1 (S, -, -)Mid-ala941 (S, -, -)112.5% (92-133)
Inline1 (S, -, -)Mid-sacrum92
Transarticular1 (S, -, -)Mid-ala131
Transarticular1 (S, -, -)Mid-sacrum133
Inline1 (-, M, -)-1891 (-, M, -)88.5% (88-89)
Transarticular1 (-, M, -)-188
Inline1 (-, -, I)-1791 (-, -, I)78.5% (78-79)
Transarticular1 (-, -, I)-178
Table 5 Change in sacroiliac joint lateral bending range of motion (°) as a result of reducing the number of implants
TreatmentImplants (positions)Superior implant ending pointRange of motion (°)Motion increase (°)% 3 implant motion
Intact--10.66--
Inline3 (S, M, I)Mid-ala0.45Reference configuration
Inline2 (S, M, -)Mid-ala0.50.0511
Inline2 (S, -, I)Mid-ala0.470.024
Inline2 (-, M, I)-10.530.0818
Inline1 (S, -, -)Mid-ala0.580.1329
Inline1 (-, M, -)-10.650.244
Inline1 (-, -, I)-10.690.2453
Inline3 (S, M, I)Mid-sacrum0.41Reference configuration
Inline2 (S, M, -)Mid-sacrum0.450.0410
Inline2 (S, -, I)Mid-sacrum0.430.025
Inline1 (S, -, -)Mid-sacrum0.580.1741
Transarticular3 (S, M, I)Mid-ala0.41Reference configuration
Transarticular2 (S, M, -)Mid-ala0.450.0410
Transarticular2 (S, -, I)Mid-ala0.420.012
Transarticular2 (-, M, I)-10.470.0615
Transarticular1 (S, -, -)Mid-ala0.580.1741
Transarticular1 (-, M, -)-10.60.1946
Transarticular1 (-, -, I)-10.620.2151
Transarticular3 (S, M, I)Mid-sacrum0.38Reference configuration
Transarticular2 (S, M, -)Mid-sacrum0.410.038
Transarticular2 (S, -, I)Mid-sacrum0.390.013
Transarticular1 (S, -, -)Mid-sacrum0.580.253
TreatmentImplants (positions)Superior implant ending point% 3 Implant motionImplants (positions)Median (%) [range]
Inline2 (S, -, I)Mid-ala42 (S, -, I)3.5% (2-5)
Inline2 (S, -, I)Mid-sacrum5
Transarticular2 (S, -, I)Mid-ala2
Transarticular2 (S, -, I)Mid-sacrum3
Inline2 (S, M, -)Mid-ala112 (S, M, -)10% (8-11)
Inline2 (S, M, -)Mid-sacrum10
Transarticular2 (S, M, -)Mid-ala10
Transarticular2 (S, M, -)Mid-sacrum8
Inline2 (-, M, I)-1182 (-, M, I)16.5% (15-18)
Transarticular2 (-, M, I)-115
Inline1 (S, -, -)Mid-ala291 (S, -, -)41% (29-53)
Inline1 (S, -, -)Mid-sacrum41
Transarticular1 (S, -, -)Mid-ala41
Transarticular1 (S, -, -)Mid-sacrum53
Inline1 (-, M, -)-1441 (-, M, -)45% (44-46)
Transarticular1 (-, M, -)-146
Inline1 (-, -, I)-1531 (-, -, I)52% (51-53)
Transarticular1 (-, -, I)-151
Table 6 Change in sacroiliac joint axial rotation range of motion (°) as a result of reducing the number of implants
TreatmentImplants (positions)Superior implant ending pointRange of motionMotion increase (°)% 3 implant motion
Intact-11.11--
Inline3 (S, M, I)Mid-ala0.41Reference configuration
Inline2 (S, M, -)Mid-ala0.490.0820
Inline2 (S, -, I)Mid-ala0.440.037
Inline2 (-, M, I)10.550.1434
Inline1 (S, -, -)Mid-ala0.670.2663
Inline1 (-, M, -)10.730.3278
Inline1 (-, -, I)10.790.3893
Inline3 (S, M, I)Mid-sacrum0.38Reference configuration
Inline2 (S, M, -)Mid-sacrum0.430.0513
Inline2 (S, -, I)Mid-sacrum0.40.025
Inline1 (S, -, -)Mid-sacrum0.610.2361
Transarticular3 (S, M, I)Mid-ala0.34Reference configuration
Transarticular2 (S, M, -)Mid-ala0.40.0618
Transarticular2 (S, -, I)Mid-ala0.360.026
Transarticular2 (-, M, I)10.460.1235
Transarticular1 (S, -, -)Mid-ala0.670.3397
Transarticular1 (-, M, -)10.70.36106
Transarticular1 (-, -, I)10.730.39115
Transarticular3 (S, M, I)Mid-sacrum0.31Reference configuration
Transarticular2 (S, M, -)Mid-sacrum0.350.0413
Transarticular2 (S, -, I)Mid-sacrum0.320.013
Transarticular1 (S, -, -)Mid-sacrum0.610.397
TreatmentImplants (positions)Superior implant ending point% 3 Implant motionImplants (positions)Median (%) [range]
Inline2 (S, -, I)Mid-ala72 (S, -, I)5.5% (3-7)
Inline2 (S, -, I)Mid-sacrum5
Transarticular2 (S, -, I)Mid-ala6
Transarticular2 (S, -, I)Mid-sacrum3
Inline2 (S, M, -)Mid-ala202 (S, M, -)15.5% (13-20)
Inline2 (S, M, -)Mid-sacrum13
Transarticular2 (S, M, -)Mid-ala18
Transarticular2 (S, M, -)Mid-sacrum13
Inline2 (-, M, I)1342 (-, M, I)34.5% (34-35)
Transarticular2 (-, M, I)135
Inline1 (S, -, -)Mid-ala631 (S, -, -)80% (61-97)
Inline1 (S, -, -)Mid-sacrum61
Transarticular1 (S, -, -)Mid-ala97
Transarticular1 (S, -, -)Mid-sacrum97
Inline1 (-, M, -)1781 (-, M, -)92% (78-106)
Transarticular1 (-, M, -)1106
Inline1 (-, -, I)1931 (-, -, I)104% (93-115)
Transarticular1 (-, -, I)1115