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J Sales De Gauzy

Publications and source records attributed to J Sales De Gauzy.

10 recordsLinked to original sources
PubMed2002

Biomechanical evaluation of Cheneau-Toulouse-Munster brace in the treatment of scoliosis using optimisation approach and finite element method.

The aim of the study was to investigate the mechanisms of the Cheneau-Toulouse-Munster (CTM) brace in the correction of scoliotic curves, at night in the supine position. Magnetic resonance imaging (MRI) and Computer tomography (CT) acquisitions were performed in vivo on eight girls having an idiopathic scoliosis and being treated for the first time using a personalized CTM brace. Personalized 3D finite element models of the spine were developed for each patient, and an optimisation approach was used to quantify the forces generated by each brace on each scoliotic spine. A sensitivity study was undertaken to test the assumptions about intervertebral behaviour and load transmission from the brace to the spine. The computed CTM brace forces were 9-216N in the coronal plane and 2-72N in the sagittal plane. Personalized spinal stiffness properties should be included in spine models because, in this study, partial correction resulted from the application of higher estimated forces than for total correction. Partially reduced spines should be stiffer than totally reduced spines. The sensitivity study showed that the computed brace forces were proportional to the intervertebral Young's modulus and should be analysed as estimated data. Better knowledge of brace forces should be helpful in brace design to achieve the best correction of first scoliotic deformities.

Adolescent↗
PubMed2002

Personalised mechanical properties of scoliotic vertebrae determined in vivo using tomodensitometry.

This in vivo study investigated the mechanical properties of apical scoliotic vertebrae using computed tomography (CT) and finite element (FE) meshing. CT examination was performed on seven scoliotic girls. FE meshing of each vertebral body allowed automatic mapping of the CT scan and the visualisation of the bone density distribution. Centroids and mass centres were compared to analyse the mechanical properties distribution. Compared to the centroid, the mass centre migrated into the concavity of the curvature. The three vertebrae of a same patient had the same body migration behaviour because they were located at the curvature apex. This observation was verified in the coronal plane, but not in the sagittal plane. These results represent new data over few geometrical analyses of scoliotic vertebrae. Same in vivo personalisation of mechanical properties should be performed on intervertebral discs or ligaments to personalise stiffness properties of the spine for the biomechanical modelling of human torso. Moreover, do this mechanical deformation of scoliotic vertebrae, that appears before the vertebral wedging, could be a predictive tool in scoliosis treatment?

Child↗
PubMed2002

CTM brace effect on scoliotic intervertebral discs using MRI method.

MRI has been clinically only used for investigation of intervertebral disc disorders. In this study, MR images were used and a new 3D modelling of the intervertebral discs was proposed. MRI examination had been performed on fourteen girls presenting an idiopathic scoliosis and wearing a first CTM brace. Using an in-house image processing software and the pre-post processing software Patran, geometrical models were obtained with and without brace for each patient. These models included the outline of the intervertebral high intensity zone, composed of the nucleus and a part of the annulus. The shift forward between disc high intensity zone centres and body centres was found to be varying from 0 to 8mm. The sagittal and coronal shifts forward appeared in the curvature convexity and were maximum at the curvature apex. The intervertebral disc wedging was found to be varying from -10 degrees to +10 degrees. On these fourteen analysed patients, the CTM brace decreased the coronal shift forward between disc high intensity zone centres and body centres, and increased the sagittal intervertebral wedging. The intervertebral disc informations obtained represented new data in the scoliotic deformation description. But this method was not adapted for a clinical use. The qualitative and quantitative data obtained will help the orthopaedist in the brace design and also the clinician in the scoliosis comprehension.

Adolescent↗
PubMed2002

In vivo quantitative analysis of scoliotic vertebrae.

An in vivo method based on CT images and finite element meshing had been developed to quantify and visualize the bone density distribution of scoliotic vertebrae. CT examination (axial acquisition of the apical, superior and inferior adjacent vertebral bodies) had been performed on seven girls presenting an idiopathic scoliosis. Using an in-house image processing software and the pre-post processor Patran, a surfacic finite element mesh of each body slice was proposed allowing an automatic mapping of the cancellous bone slices and a volumic mesh for the bone density distribution visualization. In the coronal plane, compared to the body geometrical centre, the body mechanical centre was shifted forward in the concavity of the curvature for six patients and in the convexity for one patient. For each patient, this shift forward was made in a same way for the three vertebrae. In the sagittal plane, the body mechanical inertia centre was shifted forward in the posterior side for 12 vertebrae, in the anterior side for 3 vertebrae and was not shifted forward for 6 vertebrae. This shift forward was made in the anterior side for the inferior adjacent vertebra. The shift forward by slice was made in a same way for each slice, excepted at the end plates. Besides, one can observe that the scoliotic deformation evolution seemed to modify the mechanical property distribution. The results may also suggest predictive criteria of evolution of the scoliotic deformities.

Adolescent↗
PubMed2001

In vivo geometrical evaluation of Cheneau-Toulouse-Munster brace effect on scoliotic spine using MRI method.

OBJECTIVES: The aim was to quantify the immediate effect of the Cheneau-Toulouse-Munster brace (worn at night) on scoliotic curvatures in vivo.Design. A three-dimensional geometrical model of the spine was developed using magnetic resonance images. BACKGROUND: Many corrective ortheses were proposed for the orthopaedic treatment of idiopathic scoliosis. Simple radiographs were not sufficient to analyse the three-dimensional spinal deformations. So, three-dimensional geometrical models were developed using stereoradiography and axial tomography. MRI has been only used clinically for investigation of intervertebral disc disorders. METHOD: MRI examination had been performed on 14 girls having an idiopathic scoliosis and wearing a first Cheneau-Toulouse-Munster brace. The protocol investigated was performed with and without brace. Using an in-house image processing software and the pre-post processing software Patran, two geometrical models of the spine (spine without brace and spine with brace correction) were obtained, respectively, for each patient, the models including the vertebral bodies. RESULTS: Our method reproducibility was found to be 0.5 mm on the displacements and 2.5 degrees on the rotations. The Cheneau-Toulouse-Munster brace decreased the coronal shift forward, the coronal tilt, the axial rotation, and increased the sagittal shift forward and the sagittal vertebral tilt. DISCUSSION: The results showed that the Cheneau-Toulouse-Munster brace had a three-dimensional and personalised action on vertebrae. This technique using MRI provides no irradiation and allows the soft tissue visualisation, but actually is not dedicated for clinical use and is limited to the lying position. RELEVANCE: The qualitative and quantitative data obtained allowed a better description of the Cheneau-Toulouse-Munster brace effect on scoliotic spine, and will help the orthopaedist in the brace design and the clinician in the scoliosis comprehension.

Adolescent↗
PubMed2001

Tomodensitometry measurements for in vivo quantification of mechanical properties of scoliotic vertebrae.

OBJECTIVE: This in vivo study investigated the mechanical properties of scoliotic vertebrae especially in the apical zone. DESIGN: A method based on computed tomography images and finite element meshing had been developed to quantify and visualise the bone density distribution of scoliotic vertebrae. BACKGROUND: Most of scoliotic studies performed considered only geometrical parameters. METHOD: Computed tomography examination had been performed on 11 girls presenting idiopathic scoliosis. Using in-house image processing software and the pre-post processor Patran, a finite element mesh of each vertebral body and a mapping of each cancellous bone slice were proposed allowing the bone density distribution to be visualised. The mechanical properties were derived from predictive relationships between Young's modulus and computed tomography number. Geometrical (unit mass) and mechanical centres were calculated and compared in order to quantify the role of mechanical property distribution on the apex zone of the scoliotic spine. RESULTS: In the coronal plane, compared to the geometrical centre, the mechanical centre was shifted forward in the concavity (0.54 mm) of the curvature except for two vertebrae. In the sagittal plane, the mechanical centre was shifted forward in the back (0.26 mm) except for three vertebrae. The shift forward by slice was made in a same way for each slice (0.63 mm), except at the end plates (0.58 mm). DISCUSSION: The result values obtained were small but significant because the curvatures were low and the vertebrae were not wedged. Besides, one can observe that the scoliotic deformation evolution seemed to modify the mechanical property distribution. RELEVANCE: This study suggested the following question: Could these CT measurements be a predictive tool in scoliosis treatment?

Child↗
PubMed2001

[Scarf osteotomy of hallux valgus in children and adolescents].

PURPOSE OF THE STUDY: The aim of this study was to analyze the results of surgical treatment of hallux valgus using scarf osteotomy in children and adolescents. MATERIAL AND METHOD: Twelve children and adolescents (19 feet) operated on with scarf osteotomy were reviewed retrospectively with a mean follow-up of 15 months. Clinical and radiographic results were assessed. RESULTS: We obtained 10 good results (asymptomatic cases), 9 poor with residual symptoms such as pain or cosmetic problems. Two populations could be identified considering the metatarsus varus and distal metatarsal angle. Those with metatarsus varus >/= 10 degrees or normal distal metatarsal angle had good results. Those without metatarsus varus had poor results. There was no disturbance of growth. DISCUSSION: Scarf osteotomy can be used in children without risk of hindering growth. Nevertheless, good results can be achieved only in cases of true metatarsus varus and normal distal metatarsal angle. In other cases, a different osteotomy of the first metatarsal would be preferable.

Adolescent↗
PubMed2001

[Recurrent aggressive chondroblastoma: two cases and a review of the literature].

Chondroblastoma is a rare benign bone tumor. Treatment currently consists of curettage and bone graft. Prognosis depends basically on a relatively high rate of recurrence, between 5 and 38%, sometimes with local seeding of soft tissues and joint space. Such recurrences require wide resection with arthrodesis or even amputation. A 13-year-old girl with a humeral head chondroblastoma as treated by curettage and iliac bone graft. Six months later, a recurrence occurred with extension into the rotator cuff and the metaphysis. Remission was achieved by extensive surgical resection and hemiarthroplasty. The second case was a 14-year-old boy with a chondroblastoma of the right talus. He was treated by curettage and packing with bone substitute. After 2 recurrences with soft tissue and intra-articular extension, we performed a wide resection with reconstruction using a vascularized fibular graft. Many other cases in the literature illustrate such complications. We tried to find factors predictive of recurrence. Recurrence is observed when curettage was incomplete or when tumor cells were disseminated during surgery. Chondroblastoma is a benign bone tumor, but prognosis depends on the rapidity and severity of recurrence. Curettage should be as complete as possible and care should be taken to avoid contaminating the operative field.

Adolescent↗
PubMed1994

Experimental model of posterolateral spinal arthrodesis in sheep. Part 1. Experimental procedures and results with autologous bone graft.

OBJECTIVES: The authors evaluated the reliability in obtaining a posterolateral spinal arthrodesis (PSA) with autologous bone graft. SUMMARY OF BACKGROUND DATA: Posterolateral spinal arthrodesis using autogenous cancellous bone graft is the most simple and efficient technique to get a spinal graft. No extensive biomechanical study of PSA is available. Thus, an experimental model of PSA is needed. METHODS: Eleven sheep underwent lumbar autologous bone grafts and Cotrel-Dubousset instrumentations, and four sheep were used as controls. Sacrifice and biomechanical evaluation of the lumbar spines were performed after 1 year. RESULTS: All grafts appeared continuous. A large decrease of flexibility (in rotation and in translation) was found in grafted spines in every direction. Failure in extension occurred at a mean value of 35.26 +/- 3.71 Nm. CONCLUSION: A constant and homogenous PSA appears to be obtained in sheep under conditions close to the human surgery.

Animals↗