TY - JOUR
T1 - Comprehensive biomechanical analysis of three reconstruction techniques following total sacrectomy
T2 - An in vitro human cadaveric model
AU - Macki, Mohamed
AU - De La Garza-Ramos, Rafael
AU - Murgatroyd, Ashley A.
AU - Mullinix, Kenneth P.
AU - Sun, Xiaolei
AU - Cunningham, Bryan W.
AU - McCutcheon, Brandon A.
AU - Bydon, Mohamad
AU - Gokaslan, Ziya L.
N1 - Publisher Copyright:
© AANS, 2017.
PY - 2017/11
Y1 - 2017/11
N2 - OBJECTIVE: Aggressive sacral tumors often require en bloc resection and lumbopelvic reconstruction. Instrumentation failure and pseudarthrosis remain a clinical concern to be addressed. The objective in this study was to compare the biomechanical stability of 3 distinct techniques for sacral reconstruction in vitro. METHODS: In a human cadaveric model study, 8 intact human lumbopelvic specimens (L2-pelvis) were tested for flexion-extension range of motion (ROM), lateral bending, and axial rotation with a custom-designed 6-df spine simulator as well as axial compression stiffness with the MTS 858 Bionix Test System. Biomechanical testing followed this sequence: 1) intact spine; 2) sacrectomy (no testing); 3) Model 1 (L3-5 transpedicular instrumentation plus spinal rods anchored to iliac screws); 4) Model 2 (addition of transiliac rod); and 5) Model 3 (removal of transiliac rod; addition of 2 spinal rods and 2 S-2 screws). Range of motion was measured at L4-5, L5-S1/cross-link, L5-right ilium, and L5-left ilium. RESULTS: Flexion-extension ROM of the intact specimen at L4-5 (6.34° ± 2.57°) was significantly greater than in Model 1 (1.54° ± 0.94°), Model 2 (1.51° ± 1.01°), and Model 3 (0.72° ± 0.62°) (p < 0.001). Flexion-extension at both the L5- right ilium (2.95° ± 1.27°) and the L5-left ilium (2.87° ± 1.40°) for Model 3 was significantly less than the other 3 cohorts at the same level (p = 0.005 and p = 0.012, respectively). Compared with the intact condition, all 3 reconstruction groups statistically significantly decreased lateral bending ROM at all measured points. Axial rotation ROM at L4-5 for Model 1 (2.01° ± 1.39°), Model 2 (2.00° ± 1.52°), and Model 3 (1.15° ± 0.80°) was significantly lower than the intact condition (5.02° ± 2.90°) (p < 0.001). Moreover, axial rotation for the intact condition and Model 3 at L5-right ilium (2.64° ± 1.36° and 2.93° ± 1.68°, respectively) and L5-left ilium (2.58° ± 1.43° and 2.93° ± 1.71°, respectively) was significantly lower than for Model 1 and Model 2 at L5-right ilium (5.14° ± 2.48° and 4.95° ± 2.45°, respectively) (p = 0.036) and L5-left ilium (5.19° ± 2.34° and 4.99° ± 2.31°) (p = 0.022). Last, results of the axial compression testing at all measured points were not statistically different among reconstructions. CONCLUSIONS: The addition of a transverse bar in Model 2 offered no biomechanical advantage. Although the implementation of 4 iliac screws and 4 rods conferred a definitive kinematic advantage in Model 3, that model was associated with significantly restricted lumbopelvic ROM.
AB - OBJECTIVE: Aggressive sacral tumors often require en bloc resection and lumbopelvic reconstruction. Instrumentation failure and pseudarthrosis remain a clinical concern to be addressed. The objective in this study was to compare the biomechanical stability of 3 distinct techniques for sacral reconstruction in vitro. METHODS: In a human cadaveric model study, 8 intact human lumbopelvic specimens (L2-pelvis) were tested for flexion-extension range of motion (ROM), lateral bending, and axial rotation with a custom-designed 6-df spine simulator as well as axial compression stiffness with the MTS 858 Bionix Test System. Biomechanical testing followed this sequence: 1) intact spine; 2) sacrectomy (no testing); 3) Model 1 (L3-5 transpedicular instrumentation plus spinal rods anchored to iliac screws); 4) Model 2 (addition of transiliac rod); and 5) Model 3 (removal of transiliac rod; addition of 2 spinal rods and 2 S-2 screws). Range of motion was measured at L4-5, L5-S1/cross-link, L5-right ilium, and L5-left ilium. RESULTS: Flexion-extension ROM of the intact specimen at L4-5 (6.34° ± 2.57°) was significantly greater than in Model 1 (1.54° ± 0.94°), Model 2 (1.51° ± 1.01°), and Model 3 (0.72° ± 0.62°) (p < 0.001). Flexion-extension at both the L5- right ilium (2.95° ± 1.27°) and the L5-left ilium (2.87° ± 1.40°) for Model 3 was significantly less than the other 3 cohorts at the same level (p = 0.005 and p = 0.012, respectively). Compared with the intact condition, all 3 reconstruction groups statistically significantly decreased lateral bending ROM at all measured points. Axial rotation ROM at L4-5 for Model 1 (2.01° ± 1.39°), Model 2 (2.00° ± 1.52°), and Model 3 (1.15° ± 0.80°) was significantly lower than the intact condition (5.02° ± 2.90°) (p < 0.001). Moreover, axial rotation for the intact condition and Model 3 at L5-right ilium (2.64° ± 1.36° and 2.93° ± 1.68°, respectively) and L5-left ilium (2.58° ± 1.43° and 2.93° ± 1.71°, respectively) was significantly lower than for Model 1 and Model 2 at L5-right ilium (5.14° ± 2.48° and 4.95° ± 2.45°, respectively) (p = 0.036) and L5-left ilium (5.19° ± 2.34° and 4.99° ± 2.31°) (p = 0.022). Last, results of the axial compression testing at all measured points were not statistically different among reconstructions. CONCLUSIONS: The addition of a transverse bar in Model 2 offered no biomechanical advantage. Although the implementation of 4 iliac screws and 4 rods conferred a definitive kinematic advantage in Model 3, that model was associated with significantly restricted lumbopelvic ROM.
KW - Biomechanics
KW - Galveston L-rod
KW - Lumbopelvic
KW - Sacral reconstruction
KW - Sacrectomy
KW - Sacrum
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U2 - 10.3171/2017.2.SPINE161128
DO - 10.3171/2017.2.SPINE161128
M3 - Article
C2 - 28777063
AN - SCOPUS:85032693551
SN - 1547-5654
VL - 27
SP - 570
EP - 577
JO - Journal of Neurosurgery: Spine
JF - Journal of Neurosurgery: Spine
IS - 5
ER -