Quantitative geometric analysis of rib, costal cartilage and sternum from childhood to teenagehood

Better understanding of the effects of growth on children’s bones and cartilage is necessary for clinical and biomechanical purposes. The aim of this study is to define the 3D geometry of children’s rib cages: including sternum, ribs and costal cartilage. Three-dimensional reconstructions of 960 ribs, 518 costal cartilages and 113 sternebrae were performed on thoracic CT-scans of 48 children, aged four months to 15 years. The geometry of the sternum was detailed and nine parameters were used to describe the ribs and rib cages. A "costal index" was defined as the ratio between cartilage length and whole rib length to evaluate the cartilage ratio for each rib level. For all children, the costal index decreased from rib level one to three and increased from level three to seven. For all levels, the cartilage accounted for 45 to 60% of the rib length, and was longer for the first years of life. The mean costal index decreased by 21% for subjects over three years old compared to those under three (p<10-4). The volume of the sternebrae was found to be highly age dependent. Such data could be useful to define the standard geometry of the paediatric thorax and help to detect clinical abnormalities.Grant from the ANR (SECUR_ENFANT 06_0385) and supported by the GDR 2610 “Biomécanique des chocs” (CNRS/INRETS/GIE PSA Renault

Variability of Child Rib Bone Hounsfield Units using in vivo Computed Tomography

The variability assessment of the rib bone mechanical properties during the growth process is still missing. These properties could not be obtained in vivo on children. Relationships have been obtained between Hounsfield Units from computed tomography (CT) and mechanical properties (e.g. for the cortical bone on adults). As a first step for investigation of the mechanical properties of child ribs, the aim of this study was to determine the Hounsfield Units variation of child ribs from CT‐scan data, by rib level, along the rib and within the rib sections. Twenty‐seven right ribs of levels 4, 6 and 9 were processed from 11 thoracic CT scans of children without bone lesions aged between 1 and 10 years. A first set of 10 equidistributed cross‐sections normal to the rib midline were extracted. Sixteen equally distributed elements defined 4 areas into the cortical band: internal, external, caudal and cranial. Within the rib sections, Hounsfield Units were found significantly higher in internal and external areas than in caudal and cranial. In a further step using calibrated CT scans, it would be possible to derive the mechanical properties of in vivo child ribs using bone density correlation with Hounsfield Units

Postnatal Diagnostic Workup in Children With Arthrogryposis: A Series of 82 Patients

International audienceObjective: To describe a postnatal series of patients with arthrogryposis multiplex congenita by the causal mechanisms involved. Methods: In this single-center study, the local data warehouse was used to identify patients with arthrogryposis multiplex congenita. Patients were classified into different etiologic groups. Results: Of 82 patients included, the most frequent cause of arthrogryposis multiplex congenita was a neuromuscular disorder (39%), including skeletal muscle (n = 19), neuromuscular junction (n = 3), and peripheral nerve (n = 11) involvement. In other subgroups, 19 patients (23%) were classified by disorders in the central nervous system, 5 (6%) in connective tissue, 7 (8.5%) had mixed mechanisms, and 18 (22%) could not be classified. Contractures topography was not associated with a causal mechanism. Cerebral magnetic resonance imaging (MRI), electroneuromyography, and muscle biopsy were the most conclusive investigations. Metabolic investigations were normal in all the patients tested. Targeted or whole exome sequencing diagnostic rates were 51% and 71%, respectively. Thirty-three percent of patients died (early death occurred in patients with polyhydramnios, prematurity, and ventilatory dependency). Discussion: The benefits of a precise diagnosis in the neonatal period include more tailored management of arthrogryposis multiplex congenita and better genetic information