Article Figures & Data
Figures
- Figure 1
Schematic of global, regional, and lower extremity alignment parameters assessed in this study. SVA, sagittal vertical axis; GSA, global sagittal angle; TK, T4 T12 thoracic kyphosis; LL, L1 S1 lumbar lordosis; PT, pelvic tilt; PI, pelvic incidence; SFA, sacrofemoral angle; KA, knee angle; AA, ankle angle; PS, pelvic shift.
- Figure 2
Rates of pelvic nonresponse compared across patients undercorrected relative to ideal age-specific postoperative alignment targets, patients matching ideal targets, and patients overcorrected relative to ideal targets for pelvic tilt (PT) (2a), pelvic incidence and lumbar lordosis (PI-LL) (2b), and sagittal vertical axis (SVA) (2c). These comparisons were conducted within groups of increasing baseline Scoliosis Research Society (SRS)-Schwab SVA modifier severity (0, +, and ++).
- Figure 3
Rates of pelvic nonresponse compared across patients undercorrected relative to ideal age-specific postoperative alignment targets, patients matching ideal targets, and patients overcorrected relative to ideal targets for pelvic tilt (PT) (3a), pelvic incidence and lumbar lordosis (PI-LL) (3b), and sagittal vertical axis (SVA) (3c). These comparisons were conducted within groups of increasing baseline Scoliosis Research Society (SRS)-Schwab PI-LL modifier severity (0, +, and ++).
- Figure 4
Rates of pelvic nonresponse compared across patients undercorrected relative to ideal age-specific postoperative alignment targets, patients matching ideal targets, and patients overcorrected relative to ideal targets for pelvic tilt (PT) (4a), pelvic incidence and lumbar lordosis (PI-LL) (4b), and sagittal vertical axis (SVA) (4c). These comparisons were conducted within groups of increasing baseline Scoliosis Research Society (SRS)-Schwab PT modifier severity (0, +, and ++).
- Figure 5
Case examples showing preoperative and 6 months postoperative standing lateral radiographs of a pelvic nonresponse (left) and a pelvic response patient (right).
Tables
- Table 1
Comparison of baseline demographics, surgical factors, sagittal alignment, and lower limb alignment between PNR and PR.
Baseline Measures Patient Group P Value PNR
(N = 29)PR
(N = 29)Demographics Age (y) 64.4 ± 9.8 63.1 ± 12.6 0.668 Sex (% female) 62.1% 72.4% 0.401 Body mass index (kg/m2) 27.0 ± 7.2 29.0 ± 6.7 0.302 Surgical factors Fusion length (levels) 10.8 ± 3.7 10.8 ± 4.3 0.974 Any osteotomy (%) 92.6% 91.7% 0.902 Baseline sagittal alignment Pelvic tilt (°) 29.5 ± 6.0 29.2 ± 5.4 0.820 Mismatch between pelvic incidence and lumbar lordosis (°) 29.5 ± 15.9 30.9 ± 11.8 0.699 Sagittal vertical axis (mm) 98.1 ± 56.8 109.0 ± 50.3 0.448 T4 T12 thoracic kyphosis (°) −39.0 ± 21.3 −29.7 ± 19.9 0.095 T1 spinopelvic inclination (°) 3.0 ± 7.1 4.8 ± 6.3 0.312 Baseline lower limb alignment Sacrofemoral angle (°) 208.1 ± 8.2 204.2 ± 6.5 0.065 Knee angle (°) 8.7 ± 8.0 13.7 ± 8.9 0.043 Ankle angle (°) 7.1 ± 3.9 8.8 ± 4.6 0.172 Pelvic shift (mm) 76.7 ± 44.9 92.6 ± 55.6 0.267 Global sagittal angle (°) 10.2 ± 5.3 12.3 ± 5.8 0.180 Note: Data presented as mean ± SD or %. Bolded values indicate statistical significance at P < 0.05.
PNR, pelvic nonresponders; PR, pelvic responders.
- Table 2
Rates of pre- to postoperative improvement in SRS-Schwab modifiers compared between PNR and PR.
Radiographic Modifier Improvement PNR PR P Value Improved in SRS-Schwab pelvic tilt modifier 0% 100% <0.001 Improved in SRS-Schwab pelvic incidence-lumbar lordosis modifier 48.3% 85.7% 0.003 Improved in SRS-Schwab sagittal vertical axis modifier 60.7% 64.3% 0.783 Note: Bolded values indicate statistical significance at P < 0.05.
PNR, pelvic nonresponders; PR, pelvic responders; SRS, Scoliosis Research Society.
- Table 3
Comparison of postoperative sagittal alignment and lower limb alignment between PNR and PR.
Radiographic Parameter Patient Group P Value PNR
(N = 29)PR
(N = 29)Postoperative sagittal alignment Pelvic tilt (°) 30.2 ± 6.7 17.4 ± 8.4 <0.001 Mismatch between pelvic incidence and lumbar lordosis (°) 17.0 ± 12.0 2.9 ± 10.9 <0.001 Sagittal vertical axis (mm) 51.6 ± 42.3 37.0 ± 45.6 0.209 T4 T12 thoracic kyphosis (°) −46.6 ± 13.1 −40.7 ± 18.3 0.163 T1 spinopelvic inclination (°) −3.0 ± 5.3 −1.8 ± 5.6 0.427 Postoperative lower limb alignment Sacrofemoral angle (°) 203.14 ± 38.7 198.6 ± 7.9 0.535 Knee angle (°) 2.2 ± 29.7 12.9 ± 34.6 0.227 Ankle angle (°) 8.5 ± 4.6 0.3 ± 36.1 0.240 Pelvic shift (mm) 52.6 ± 30.8 31.2 ± 35.6 0.021 Global sagittal angle (°) 9.4 ± 16.2 3.8 ± 4.3 0.096 Note: Data presented as mean ± SD. Bolded values indicate statistical significance at P < 0.05.
PNR, pelvic nonresponders; PR, pelvic responders.
- Table 4
Comparison of pre- to postoperative changes in lower limb alignment, as well as rates of residual postoperative lower extremity compensation, between PNR and PR.
Radiographic Parameter Patient Group P Value PNR
(N = 29)PR
(N = 29)Pre- to postoperative change in lower limb alignment Sacrofemoral angle (°) 2.1 ± 5.8 −5.3 ± 7.0 <0.001 Pelvic shift (mm) −24.1 ± 37.3 −63.7 ± 42.5 0.001 Pelvic femoral angle (°) −1.4 ± 2.2 −3.8 ± 3.0 0.002 Global sagittal angle (°) −3.5 ± 4.8 −8.8 ± 4.4 <0.001 Rates of persistent postoperative lower extremity compensation Sacrofemoral angle 68% 25% 0.003 Ankle flexion 64% 33% 0.032 Pelvic shift 28% 4% 0.049 Note: Data presented as mean ± SD or %. Bolded values indicate statistical significance at P < 0.05.
PNR, pelvic nonresponders; PR, pelvic responders.
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