Cyrus M Jalai1, Bassel G Diebo2, Dana L Cruz1, Gregory W Poorman2, Shaleen Vira1, Aaron J Buckland1, Renaud Lafage2, Shay Bess1, Thomas J Errico1, Virginie Lafage2, Peter G Passias3. 1. Department of Orthopaedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, 301 East 17th St, New York, NY 10003, USA. 2. Department of Orthopaedic Surgery, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021, USA. 3. Department of Orthopaedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, 301 East 17th St, New York, NY 10003, USA. Electronic address: peter.passias@nyumc.org.
Abstract
BACKGROUND CONTEXT: Obesity's impact on standing sagittal alignment remains poorly understood, especially with respect to the role of the lower limbs. Given energetic expenditure in standing, a complete understanding of compensation in obese patients with sagittal malalignment remains relevant. PURPOSE: This study compares obese and non-obese patients with progressive sagittal malalignment for differences in recruitment of pelvic and lower-limb mechanisms. STUDY DESIGN/ SETTING: Single-center retrospective review. PATIENT SAMPLE: A total of 554 patients (277 obese, 277 non-obese) were identified for analysis. OUTCOME MEASURES: Upper body alignment parameters: sagittal vertical axis (SVA) and T1 spinopelvic inclination (T1SPi). Compensatory lower-limb mechanisms: pelvic translation (pelvic shift [PS]), knee (KA) and ankle (AA) flexion, hip extension (sacrofemoral angle [SFA]), and global sagittal angle (GSA). METHODS: Inclusion criteria were patients ≥18 years who underwent full-body stereographic x-rays. Included patients were categorized as non-obese (N-Ob: body mass index [BMI]<30 kg/m2) or obese (Ob: BMI≥30 kg/m2). To control for potential confounders, groups were propensity score matched by age, gender, and baseline pelvic incidence (PI), and subsequently categorized by increasing spinopelvic (pelvic incidence minus lumbar lordosis [PI-LL]) mismatch: <10°, 10°-20°, >20°. Independent t tests and linear regression models compared sagittal (SVA, T1SPi) and lower limb (PS, KA, AA, SFA, GSA) parameters between obesity cohorts. RESULTS: A total of 554 patients (277 Ob, 277 N-Ob) were included for analysis and were stratified to the following mismatch categories: <10°: n=367; 10°-20°: n=91; >20°: n=96. Obese patients had higher SVA, KA, PS, and GSA than N-Ob patients (p<.001 all). Low PI-LL mismatch Ob patients had greater SVA with lower SFA (142.22° vs. 156.66°, p=.032), higher KA (5.22° vs. 2.93°, p=.004), and higher PS (4.91 vs. -5.20 mm, p<.001) than N-Ob patients. With moderate PI-LL mismatch, Ob patients similarly demonstrated greater SVA, KA, and PS, combined with significantly lower PT (23.69° vs. 27.14°, p=.012). Obese patients of highest (>20°) PI-LL mismatch showed greatest forward malalignment (SVA, T1SPi) with significantly greater PS, and a concomitantly high GSA (12.86° vs. 9.67°, p=.005). Regression analysis for lower-limb compensation revealed that increasing BMI and PI-LL predicted KA (r2=0.234) and GSA (r2=0.563). CONCLUSIONS: With progressive sagittal malalignment, obese patients differentially recruit lower extremity compensatory mechanisms, whereas non-obese patients preferentially recruit pelvic mechanisms. The ability to compensate for progressive sagittal malalignment with the pelvic retroversion is limited by obesity.
BACKGROUND CONTEXT: Obesity's impact on standing sagittal alignment remains poorly understood, especially with respect to the role of the lower limbs. Given energetic expenditure in standing, a complete understanding of compensation in obesepatients with sagittal malalignment remains relevant. PURPOSE: This study compares obese and non-obesepatients with progressive sagittal malalignment for differences in recruitment of pelvic and lower-limb mechanisms. STUDY DESIGN/ SETTING: Single-center retrospective review. PATIENT SAMPLE: A total of 554 patients (277 obese, 277 non-obese) were identified for analysis. OUTCOME MEASURES: Upper body alignment parameters: sagittal vertical axis (SVA) and T1 spinopelvic inclination (T1SPi). Compensatory lower-limb mechanisms: pelvic translation (pelvic shift [PS]), knee (KA) and ankle (AA) flexion, hip extension (sacrofemoral angle [SFA]), and global sagittal angle (GSA). METHODS: Inclusion criteria were patients ≥18 years who underwent full-body stereographic x-rays. Included patients were categorized as non-obese (N-Ob: body mass index [BMI]<30 kg/m2) or obese (Ob: BMI≥30 kg/m2). To control for potential confounders, groups were propensity score matched by age, gender, and baseline pelvic incidence (PI), and subsequently categorized by increasing spinopelvic (pelvic incidence minus lumbar lordosis [PI-LL]) mismatch: <10°, 10°-20°, >20°. Independent t tests and linear regression models compared sagittal (SVA, T1SPi) and lower limb (PS, KA, AA, SFA, GSA) parameters between obesity cohorts. RESULTS: A total of 554 patients (277 Ob, 277 N-Ob) were included for analysis and were stratified to the following mismatch categories: <10°: n=367; 10°-20°: n=91; >20°: n=96. Obesepatients had higher SVA, KA, PS, and GSA than N-Ob patients (p<.001 all). Low PI-LL mismatch Ob patients had greater SVA with lower SFA (142.22° vs. 156.66°, p=.032), higher KA (5.22° vs. 2.93°, p=.004), and higher PS (4.91 vs. -5.20 mm, p<.001) than N-Ob patients. With moderate PI-LL mismatch, Ob patients similarly demonstrated greater SVA, KA, and PS, combined with significantly lower PT (23.69° vs. 27.14°, p=.012). Obesepatients of highest (>20°) PI-LL mismatch showed greatest forward malalignment (SVA, T1SPi) with significantly greater PS, and a concomitantly high GSA (12.86° vs. 9.67°, p=.005). Regression analysis for lower-limb compensation revealed that increasing BMI and PI-LL predicted KA (r2=0.234) and GSA (r2=0.563). CONCLUSIONS: With progressive sagittal malalignment, obesepatients differentially recruit lower extremity compensatory mechanisms, whereas non-obesepatients preferentially recruit pelvic mechanisms. The ability to compensate for progressive sagittal malalignment with the pelvic retroversion is limited by obesity.
Authors: Jannat M Khan; Bryce A Basques; Kyle N Kunze; Gagan Grewal; Young Soo Hong; Coralie Pardo; Philip K Louie; Matthew Colman; Howard S An Journal: Eur Spine J Date: 2019-08-16 Impact factor: 3.134
Authors: Gennadiy A Katsevman; Scott D Daffner; Nicholas J Brandmeir; Sanford E Emery; John C France; Cara L Sedney Journal: Spine J Date: 2019-12-24 Impact factor: 4.166
Authors: Peter G Passias; Frank A Segreto; Bailey Imbo; Tyler Williamson; Rachel Joujon-Roche; Peter Tretiakov; Oscar Krol; Sara Naessig; Cole A Bortz; Samantha R Horn; Waleed Ahmad; Katherine Pierce; Yael U Ihejirika; Virginie Lafage Journal: Spine Deform Date: 2022-06-03
Authors: Samantha R Horn; Cole A Bortz; Subaraman Ramachandran; Gregory W Poorman; Frank Segreto; Matt Siow; Akhila Sure; Dennis Vasquez-Montes; Bassel Diebo; Jared Tishelman; John Moon; Peter Zhou; Bryan Beaubrun; Shaleen Vira; Cyrus Jalai; Charles Wang; Kartik Shenoy; Omar Behery; Thomas Errico; Virginie Lafage; Aaron Buckland; Peter G Passias Journal: Int J Spine Surg Date: 2019-06-30