SAM

Barycentremetry, spine disorders, posture and motion analysis

SKALLI, Wafa — Wed, 01 Oct 2025 00:00:00 GMT

Barycentremetry, spine disorders, posture and motion analysis SKALLI, Wafa; KHALIFÉ, Marc; FERRERO, EMMANUELLE; VERGARI, Claudio; GHANEM, Ismat; ASSI, Ayman Purpose of the research Prevention of spine disorders and their management require better understanding of related biomechanical issues. While tremendous progress has been performed for musculoskeletal modelling of the spine, subject specific modelling of the gravitational loads and their effects on the spine is still an issue. Recently, 3D reconstruction of the skeleton from biplanar head to feet X-rays in erect position has been completed by the external body envelope. An approach named “barycentremetry” based on density models to estimate the mass and centre of mass of each body segment, yielding a force plate less estimation of the gravity line, together with the estimation of the gravitational loads and the associated lever arm at each vertebral level. Principal results Due to vertebral pose, gravitational loads effect on intervertebral disc shows wide variation. Studies exploring barycentremetry clinical relevance were analysed, particularly for adolescent idiopathic scoliosis, adult spinal deformities and osteoporosis. They progressively yield a better comprehension of the potential vicious circles linking postural disorder to increase of spine loads to increase of postural disorder. Barycentremetry was also explored within gait and motion analysis research, allowing to estimate subject specific body segments inertial parameters for patient specific dynamic analysis. Indeed, 3D musculoskeletal modelling of posture and motion could benefit from subject specific dynamic analysis based on barycentremetry. Major conclusions Such approaches progressively provide a better understanding of the stability of this complex system and compensation strategies that could be useful for early detection of disorders that are responsible of a biomechanical cascade

Femoral neck version in the spinopelvic and lower limb 3D alignment: a full-body EOS® study in 400 healthy subjects

KHALIFE, Marc — Fri, 01 Sep 2023 00:00:00 GMT

Femoral neck version in the spinopelvic and lower limb 3D alignment: a full-body EOS® study in 400 healthy subjects KHALIFE, Marc; VERGARI, Claudio; REBEYRAT, Guillaume; FERRERO, EMMANUELLE; GUIGUI, Pierre; ASSI, Ayman; SKALLI, Wafa Background: The goal of this study was to better understand the variation of femoral neck version according to spinopelvic and lower limb 3D alignment using biplanar X-rays in standing position. Methods: This multicentric study retrospectively included healthy subjects from previous studies who had free-standing position biplanar radiographs. Subjects were excluded if they presented spinal or any musculo-skeletal deformity, and reported pain in the spine, hip or knee. Age, sex, and the following 3D-reconstructed parameters were collected: spinal curvatures, pelvic parameters, sagittal vertical axis (SVA), T1 pelvic angle (TPA), spino-sacral angle (SSA), femoral torsion angle (FTA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle angle (AA), pelvic shift (PS) and ankle distance. Femoral neck version angle (FVA) was calculated between horizontal plane projection of the bi-coxo-femoral axis and the line passing through the femoral neck barycenter and femoral head center. Analysis according to age subsets was performed. Results: A total of 400 subjects were included (219 females); mean age was 29 ± 18 years (range: 4-83). Subjects with high pelvic tilt values presented significantly higher FVA than average and low-PT individuals, respectively, 7.8 ± 7.1°, 2 ± 9° and 2.1 ± 9.5° (p < 0.001). These subjects also presented lower lumbar lordosis values and higher acetabulum anteversion in the horizontal plane than the two other groups. SVA correlation with FVA was weaker (r = 0.1, p = 0.03) than SSA and TPA (r = - 0.3 and r = 0.3, respectively, p < 0.001). A strong correlation was found with femoral torsion (r = 0.5, p < 0.001). SFA (r = - 0.3, p < 0.001), pelvic shift (r = 0.2, p < 0.001) and ankle distance (r = 0.3, p < 0.001) were also significantly correlated. Multivariate analysis confirmed significant association of age, pelvic tilt, lumbar lordosis, pelvic shift, ankle distance and femoral torsion with FVA. Conclusion: Patients with lower lumbar lordosis present pelvic retroversion which induces a higher femoral neck version. This finding may help positioning implants in total hip replacement procedures. Higher pelvic shift, age, male gender and increased femoral torsion were also correlated with higher FVA. Pas de financement pour cet article.

The relative contribution of discs and vertebral bodies to thoracic kyphosis in healthy volunteers

FINOCO, Mikael — Mon, 06 Oct 2025 00:00:00 GMT

The relative contribution of discs and vertebral bodies to thoracic kyphosis in healthy volunteers FINOCO, Mikael; LAFAGE, Renaud; VERGARI, Claudio; SKALLI, Wafa; ELYSEE, Jonathan; ASSI, Ayman; GUIGUI, Pierre; FERRERO, EMMANUELLE; LAFAGE, Virginie; KHALIFÉ, Marc Introduction : Understanding the normal anatomy of thoracic kyphosis (TK) in healthy subjects is essential for evaluating sagittal malalignment and planning the surgery accordingly. The aim of this study was to identify the proportion of thoracic kyphosis originating from disc versus vertebral body shape and to describe its variation according to age and thoracic kyphosis magnitude. Methods : This study was a retrospective review of a prospective multicenter database of healthy volunteers aged 18 years or older. Vertebral body and disc sagittal Cobb angles were measured at each level and summed within each of the 3 TK regions (Upper, Middle and Lower TK). Relative contributions of discs and vertebral bodies to Upper, Middle, Lower, and total TK were assessed in the whole cohort, and according to age and TK groups, after stratification. Finally, a multivariate analysis including age and TK magnitude was conducted. Results : Among these 645 subjects, the mean age was 37.6 ± 16.3 years with 51% of females. Intervertebral discs were kyphotic in Upper and Middle TK with respective discs contribution to total TK of 4.2% and 9.6%, for a total of 13.8% of total kyphosis. Lower TK discs were lordotic, with a participation of -13.2% of total TK, leading to an overall discs contribution to TK of 0.6%. Vertebral bodies were all kyphotic with a contribution of 99.4% of total kyphosis. Vertebral bodies kyphosis increased across age groups for Middle TK (p = 0.004), Lower TK (p < 0.001), and Total TK (p < 0.001). Discs contributions to total TK increased significantly with increasing TK (-13.8% for Low TK, -1.5% for Average-Low TK, 5.7% for Average-High TK and 9.1% for High TK), (p < 0.001). Finally, discs contribution was significantly greater in males than in females, with respective values of 2.6% and -1.8% (p = 0.01). Conclusion : This study highlights the predominant role of vertebral bodies contribution to thoracic kyphosis, 99.4% on average. The contribution of disc to thoracic kyphosis (values ranging from -13.8% to 9.1%) increases significantly with increasing thoracic kyphosis magnitude. The association of age with thoracic kyphosis was greater for vertebral bodies than discs, particularly in Middle and Lower TK.