Full-body Postural Alignment Analysis Through Barycentremetry

Marc Khalifé; Claudio Vergari; Ayman Assi; Pierre Guigui; Valérie Attali; Rémi Valentin; Saman Vafadar; Emmanuelle Ferrero; Wafa Skalli

doi:10.1097/BRS.0000000000005001

Full-body Postural Alignment Analysis Through Barycentremetry

Spine (Phila Pa 1976). 2024 Apr 4. doi: 10.1097/BRS.0000000000005001. Online ahead of print.

Authors

Marc Khalifé^{1

2

3}, Claudio Vergari³, Ayman Assi^{3

4}, Pierre Guigui^{1

2}, Valérie Attali^{3

5

6}, Rémi Valentin^{3

5

6}, Saman Vafadar³, Emmanuelle Ferrero^{1

2}, Wafa Skalli³

Affiliations

¹ Orthopaedic Surgery Department, Spine Unit, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France.
² Université Paris-Cité, Paris, France.
³ Arts et Métiers Institute of Technology, Université Sorbonne Paris Nord, IBHGC - Institut de Biomécanique Humaine Georges Charpak, HESAM Université, 75013 Paris, France.
⁴ Faculty of Medicine, Saint-Joseph University, Beirut, Lebanon.
⁵ Service des Pathologies du Sommeil (Département "R3S"), Hôpitaux Universitaires Pitié Salpêtrière - Charles Foix, Assistance Publique Hôpitaux de Paris (APHP), Paris, France.
⁶ UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, INSERM, Paris, France.

PMID: 38571297
DOI: 10.1097/BRS.0000000000005001

Abstract

Study design: Multicentric retrospective.

Objective: The study of center of mass (COM) locations (i.e. barycentremetry) can help us understand postural alignment. This study goal was to determine relationships between COM locations and global postural alignment X-ray parameters in healthy subjects. The second objective was to determine the impact on spinopelvic alignment of increased distance between anterior body envelope and spine at lumbar apex level.

Summary of background data: Unexplored relationship between COM location and spinopelvic parameters.

Methods: This study included healthy volunteers with full-body biplanar radiograph including body envelope reconstruction, allowing the estimation of COM location. The following parameters were analyzed: lumbar lordosis (LL), thoracic kyphosis (TK), cervical lordosis (CL), pelvic tilt (PT), Sacro-femoral angle (SFA), Knee flexion angle (KFA), sagittal odontoid-hip axis angle (ODHA). The following COM in the sagittal plane were located: whole body, at thoracolumbar inflexion point, and body segment above TK apex. The body envelope reconstruction also provided the distance between anterior skin and the LL apex vertebral body center ("SV-L distance").

Results: This study included 124 volunteers, with a mean age of 44±19.3. Multivariate analysis confirmed posterior translation of COM above TK apex with increasing LL (P=0.002) through its proximal component, and posterior shift of COM at inflexion point with increasing TK (P=0.008). Increased SV-L distance was associated with greater ODHA (r=0.4) and more anterior body COM (r=0.8), caused by increased TK (r=0.2) and decreased proximal and distal LL (both r=0.3), resulting in an augmentation in SFA (r=0.3) (all P<0.01).

Conclusions: Barycentremetry showed that greater LL was associated with posterior shift of COM above thoracic apex while greater TK was correlated with more posterior COM at inflexion point. Whole-body COM was strongly correlated with ODHA. This study also exhibited significant alignment disruption associated with increased abdominal volume, with compensatory hip extension.

Level of evidence: II.