par Beyer, Benoît ;Feipel, Véronique ;Sholukha, Victor ;Chèze, Laurence;Van Sint Jan, Serge
Référence 25th congress of the International society of biomechanics(25th: 07-2015: Glasgow), Abstract book, , 25th congress of International society of biomechanics
Publication Publié, 2015-07
Abstract de conférence
Résumé : Introduction and objectives: Relation between rib kinematics and thorax global shape variations is described in the literature but data and analysis of segmental costovertebral joint complexes (CVJ) kinematics are lacking. A thorax 3D model of breathing motion was previously obtained and rib kinematics relative to vertebra was analyzed for upper thoracic levels in a sample of asymptomatic subjects (1). This study proposes an extended description in normal subjects from thoracic levels 1 to 9 and attempts to analyse the relation between inspiratory capacity and rib kinematics. The full method is then applied to a sample of patients with cystic fibrosis. Methods: In vivo computed tomography (CT) imaging was obtained at three different lung volumes (total lung capacity, middle of inspiratory capacity and functional residual capacity) calibrated according to plethysmography. Data from 9 patients with cystic fibrosis and 10 asymptomatic subjects were processed using a previously described method (1). 3D models of ribs and vertebrae were reconstructed for thoracic levels 1 to 9. Custom made software was used for virtual palpation (2) aiming to define 5 anatomical landmarks (ALs) on each vertebra and rib. Local anatomical coordinate systems were constructed following anatomical planes (figure 1a). Kinematics was processed using orientation vector and mean helical axis parameters (MHA) at each level to obtain angular displacements around each reference axis. A fusion method (2) of ALs with 3D models was used to obtain visualisation of both motion and kinematic parameters. Non parametric statistical test for independent samples was used to analyse the influence of pathological conditions on kinematics parameters. Pearson’s correlation coefficient was used to analyse the link between kinematics and anthropometrical parameters in both groups.Results: An advanced 3D model of continuous motion and kinematic parameters visualisation was achieved. Rib angular displacements occurred around dorso-ventral (i.e. pump handle motion) and medio-lateral (i.e. bucket handle motion) axes similarly at each CVJ level and MHA orientations were similar. Mean ranges of motion around both axes decreased with rib number (figure 1b) in both groups (around lateral axis: [from 12.2° to 5.7°] from level 1 to 9 in normal subjects; [from 8.7° to 3.6°] in cystic fibrosis group; around medio lateral axis: [from 9.5° to 3.8°] in normal subjects; [from 9.5 to 3.7°] in cystic fibrosis group). A correlation was found between rib kinematics around the medio-lateral axis and inspiratory capacity only in the cystic fibrosis group (r >0.7). Significant differences in rib kinematics around the medio-lateral axis were found between groups (p<0.05) at almost all thoracic levels.Conclusion: The 3D model of the costovertebral joint during breathing allows visualisation and quantification of segmental kinematics parameter. The influence of a clinical condition was tested and it appeared that kinematics parameters were reduced in patients with cystic fibrosis. Correlation between segmental kinematics and inspiratory capacity was demonstrated only in the cystic fibrosis group but not in normal subjects. These results suggest the hypothesis of an influence of external parameters on volume displacement such as an increase of respiratory muscle activity in patients with cystic fibrosis (3). 1. Beyer B. et al; Clin Biomech 29: 434–438 (2014).2. Keens TG et al; Am Rev Respir Dis 116: 853–860, 1977.3. Van Sint Jan S. et al, Médecine/Sciences 29: 529–536, 2013.