Biomedical subjects
J Sales de Gauzy
Publications and source records attributed to J Sales de Gauzy.
A method to investigate intervertebral disc morphology from MRI in early idiopathic scoliosis: a preliminary evaluation in a group of 14 patients.
The aim of the study was to implement a methodology to quantify in vivo and from magnetic resonance imaging (MRI) the 3D geometrical properties of intervertebral discs (IVDs) in early idiopathic scoliosis with small curves. MRI data were posttreated using a custom-made image processing software to semiautomatically determine the location of disc centres, the location of the nucleus pulposus (NP) and the ratio between the NP volume and the disc volume. MRI was performed in a clinical protocol involving 14 patients having an early idiopathic scoliosis. First, the 3D reconstruction errors were quantified using a reproducibility test (intraoperator and interoperator) in one IVD (L5-S1). The maximal errors in location were 0.79 mm in the frontal plane, 1.84 mm in the sagittal plane and 0.76 mm in the vertical plane. The maximal error in relative volume was 42%. Second, the nucleus migration and relative volume were quantified in discs T5-T6 to L5-S1. No significant relative volume variation was detected. Concerning the disc migration, no significant differences were found in the sagittal and axial planes. In the frontal plane, significant differences were observed at the apex of the scoliotic curvature when the Cobb angle was > or =20 degrees . This innovative study in early scoliosis showed reproducible preliminary results, and its application to improve diagnosis and follow-up will be established in an enlarged patient database.
[Orthopaedic complications of neurofibromatosis].
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[Avulsion fractures of the greater trochanter in children: two cases, review of the literature and proposition for a classification].
Avulsion fractures of the greater trochanter are very rare in children. We report two such cases which led to femoral head necrosis. Based on these two cases and an extensive review of the literature, we discuss the pathophysiology of this complication and propose a new classification system. Three types of lesions can be identified as a function of the mechanism causing fracture. Type 1 lesions are avulsion fractures of the greater trochanter secondary to acute contraction of the gluteus muscles. This contraction produces a vertical displacement of the greater trochanter. Femoral head necrosis has never been reported as a complication after this type of fracture mechanism. Type 2 avulsion fractures are associated with fracture of the femoral neck with a subsequent risk of femoral head necrosis. Type 3 associates hip dislocation with apophyseal avulsion with, according to the literature, an inevitable progression to head necrosis. The two cases reported look identical with those described by Linhart and Kawenblum illustrate type 3 avulsion fractures of the greater trochanter.
Does the meniscus exist in the elbow joint in children?
The authors report a case of meniscus at the elbow joint in a 15-month-old infant causing a limitation of elbow extension. Histological examination demonstrated that this tissue was not a synovial fold or a chondroid metaplasia of the synovial fold. As a meniscus does not appear at any stage of the embryological evolution of the elbow joint, it has been concluded that the presence of the meniscus can be considered as an abnormal condition.
Correlation between nucleus zone migration within scoliotic intervertebral discs and mechanical properties distribution within scoliotic vertebrae.
Correlations between intervertebral disc degeneration and bone mass were investigated previously, but never on scoliotic patients. Using MRI measurements of intervertebral discs behavior and vertebral bone tomodensitometry, correlations between nucleus zone displacement within intervertebral discs and mechanical center migration within vertebral bodies were investigated in vivo on scoliotic patients. The protocol, performed on eleven scoliotic girls, was composed of a CT scan acquisition of apical and adjacent vertebrae followed by a MRI acquisition of the thoracolumbar spine. The displacement between the vertebral body centroid and inertia center was computed from the CT images and called the mechanical migration. The displacement between nucleus zones and vertebral body centroids was quantified from MRI and called the nucleus zone migration. For apical vertebrae, a significant correlation was found in the coronal plane (r = 0.766, p < 0.01), but not in the sagittal plane (r = -0.349, p > 0.05). For adjacent vertebrae, significant correlations were found in both coronal (r = -0.633, p < 0.05) and sagittal (r = -0.797, p < 0.01) planes. The nucleus zone migration occurred in the convexity of the curvature whereas the mechanical migration occurred in the concavity.Known secondary mechanical phenomenon of scoliosis was quantified using new parameters describing intervertebral discs and vertebral bodies. Further investigations should be performed to explain the mechanical evolution of scoliosis and to use these parameters in predictive criteria of scoliosis.
Intervertebral disc modeling using a MRI method: migration of the nucleus zone within scoliotic intervertebral discs.
MRI is increasingly being used for etiologic examination of scoliosis and for intervertebral disc disorder analysis, but until now has not been applied to geometric modeling. The aim of this study was to develop a new geometric model of intervertebral discs using MRI and to quantify the migration of the nucleus zone within scoliotic intervertebral discs. Fourteen lumbar scoliotic children (Cobb angles 22 +/- 7 degrees ) were examined using MRI. The protocol consisted of sagittal and coronal plane acquisitions of the entire spine. An image processing software allowed the outline detection of the nucleus zone (intervertebral high intensity portion). The vertebral bodies were also reconstructed. Using a pre-post processor, the nucleus zone migration and a wedging angle were quantified. Statistical tests showed the repeatability of the method (p > 0.4). Nucleus zone migration was correlated to the wedging angle (r(2) = 0.488, p < 0.0001) in the coronal plane. Our results were in agreement with the literature: when two vertebrae move deforming the disc, the nucleus moves into the convexity of the curvature. But should we talk about the nucleus? Despite image processing software allowing the highlighting of image features (automatic color lookup tables applied to grayscale images using pixel intensity measurements), it is impossible to differentiate the nucleus from the annulus on T2 weighting images of adolescent spine. This new geometric model of the intervertebral disc, used for the quantification of the nucleus zone migration, should be of interest for further investigation of stiffness parameters of spine.
[Imaging of the hip in healthy children in MRI: evaluation of the acetabular coverage].
PURPOSE: To define with MR imaging a reference value for acetabular coverage on coronal and sagittal images for a population of healthy children. MATERIALS AND METHODS: 36 children (72 hips) where prospectively studied over 1 year. T1-weighted spin-echo images in both coronal and sagittal planes were obtained. Slice thickness was 4 mm. Measurement of acetabular coverage (AHI: Acetabular-Head Index) was made in both planes with two different landmarks: bone and cartilage. Study of the evolution with age was made. RESULTS: The acetabular coverage is symmetrical and decreases with age. Its measurement is reproducible. CONCLUSION: This study shows that measurement of acetabular coverage (AHI) is easily obtained at MR imaging and is reproducible. We suggest 83 (mean 1SD) as the inferior limit for AHI based on cartilage measurements. We introduce sagittal values, never published. We believe that MR, by its ability to demonstrate the cartilaginous surfaces, will play a major role in the true understanding of the anatomical relationship between the femoral head and the acetabulum.
Repair of lumbar spondylolysis using Morscher material: 14 children followed for 1-5 years.
We evaluated the results of spondylolysis repair in children and adolescents with the Morscher system. 14 patients (8 girls) with symptomatic spondylolysis unresponsive to closed treatment were operated on. Mean age at operation was 12 (7-15) years. The average follow-up was 33 (16-66) months. Results were assessed clinically according to the Henderson classification and radiographically. Clinical results were excellent in 9 patients, good in 4 and poor in 1. Radiographs showed that fusion was obtained in 12 patients, it was doubtful in 1 and 1 patient had non-union. Loosening of the screw on one or both sides was noted in 8 patients and necessitated removal of the osteosynthesis material which, however, did not alter the final outcome. The satisfactory results obtained in our series are similar to those reported in the literature.
Assessment of hindfoot deformity by three-dimensional MRI in infant club foot.
In 12 infants aged under 16 months with unilateral club foot we used MRI in association with multiplanar reconstruction to calculate the volume and principal axes of inertia of the bone and cartilaginous structures of the hindfoot. The volume of these structures in the club foot is about 20% smaller than that in the normal foot. The reduction in volume of the ossification centre of the talus (40%) is greater than that of the calcaneus (20%). The long axes of both the ossification centre and the cartilaginous anlage of the calcaneus are identical in normal and club feet. The long axis of the osseous nucleus of the talus of normal and club feet is medially rotated relative to the cartilaginous anlage, but the angle is greater in club feet (10 degrees v 14 degrees). The cartilaginous structure of the calcaneus is significantly medially rotated in club feet (15 degrees) relative to the bimalleolar axis. The cartilaginous anlage of the talus is medially rotated in both normal and club feet, but with a smaller angle for club feet (28 degrees v 38 degrees). This objective technique of measurement of the deformity may be of value preoperatively.
Congenital pseudarthrosis of the clavicle and thoracic outlet syndrome in adolescence.
A 15-year-old girl with thoracic outlet syndrome associated with congenital pseudarthrosis of the clavicle was examined. The indication for treatment of congenital pseudarthrosis of the clavicle is discussed.
Natural course of osteochondritis dissecans in children.
Results are reported from an absence of physiotherapic, orthopaedic, or surgical treatment in 31 cases of osteochondritis dissecans in 24 children. The mean age at diagnosis was 11 years and 4 months, and all the children were suffering from pain for an average of 3 months. None of these children were treated, except for instructions to discontinue involvement in sports activities until their pain had disappeared. In all cases pain disappeared, and these children have all returned to their former activities. According to x-ray findings, 30 lesions disappeared totally, although there was one case of a loose body. As a result, absence of treatment is recommended for osteochondritis dissecans in children.
Imaging evaluation of subluxation in Legg-Calvé-Perthes disease: magnetic resonance imaging compared with the plain radiograph.
The aim of the study was to evaluate the advantages of magnetic resonance imaging (MRI) in determining subluxation in Legg-Calvé-Perthes (LCPD) disease. Twenty-six patients with unilateral LCPD received 33 MRI and plain radiographs. For each patient, acetabulum head index (AHI) was measured on both hips (affected and unaffected) in a blinded fashion. Measurements were made from the cortical bone margin on the plain radiograph and from the cartilaginous surfaces on MRI. On the unaffected side AHI was 92.8% on the plain radiograph and 85% on MRI. On the affected side, AHI was 87% on the plain radiograph and 77% on MRI. These differences were statistically significant. With regard to the unaffected side, the femoral head should be considered subluxated if AHI is less than 86% on the plain radiograph and less than 77% on MRI. On the affected side, in 14 cases the femoral head was well-contained on both the plain radiograph and MRI. In 11 patients the femoral head was subluxated both on the plain radiograph and on MRI. In 8 patients the femoral head was well-contained on the plain radiograph but subluxated on MRI. This was due to thickening of the cartilaginous portion of the femoral head, which was clearly seen on MRI. MRI appeared to be more sensitive in determining the subluxation of the femoral head during the active phase of LCPD.
[Behavior of the growth cartilage submitted to hyperpressure].
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[Value of the study of somatosensory evoked potentials during surgical correction of scoliosis associated with syringomyelia. Apropos of 4 cases].
PURPOSE OF THE STUDY: The presence of a syringomyelia cavity increases the rate of neurological complications on the course of surgical treatment of scoliosis. We have evaluated the results of monitoring of somatosensory evoked potentials (SEP) in these situations. MATERIAL AND METHODS: Four patients presenting a scoliosis associated with syringomyelia have been operated through a posterior-approach with CD instrumentation. SEP monitoring was performed pre and intraoperatively. We studied the latency and the amplitude of P40. RESULTS: Preoperative SEP showed in all cases posterior spinal cord involvement (even without clinical manifestations). During monitoring, we noted in one case no variation. In one case a flattening of the response with normalisation within 5 minutes. In two cases a persistent flattening with normalisation within 10 and 15 minutes following modification of the instrumentation. In all cases, postoperative neurological status was identical to preoperative one. DISCUSSION: Preoperative SEP can make the diagnosis of posterior spinal cord involvement even when clinical status is normal. The extent of the preoperative SEP abnormalities may preclude the risk of intraoperative neurological complications. Intraoperative SEP can be performed with the same anesthetic protocol and the same technique used when operating idiopathic scoliosis. The results seem reliable. When alteration occur as for idiopathic scoliosis alteration of the amplitude appears earlier than alteration of the P40 latency. Restoration of normal responses appears later than in idiopathic scoliosis. CONCLUSION: SEP monitoring should diminish the risk for neurological complications in the course of surgical treatment of scoliosis associated with syringomyelia.
Development of the clinical tibiofemoral angle in normal adolescents. A study of 427 normal subjects from 10 to 16 years of age.
We measured the clinical tibiofemoral (TF) angle and the intercondylar (IC) or intermalleolar (IM) distance in 427 normal European children (212 male and 215 female) aged from 10 to 16 years. In our study, girls had a constant valgus (5.5 degrees) and displayed an IM distance of < 8 cm or an IC distance of < 4 cm. By contrast, boys had a varus evolution (4.4 degrees) during the last two years of growth and displayed an IM distance of < 4 cm or an IC distance of < 5 cm. Values above these for genu varum or genu valgum may require careful follow-up and evaluation.
[Cervical spondylolysis in children. Apropos of 4 cases. Review of the literature].
PURPOSE OF THE STUDY: A clinical and radiological study of four cases of spondylolysis in children. Literature review shows the congenital origin of the disorder and how it is to be treated. MATERIAL AND METHODS: We report on four children with cervical spondylolysis. One of the children presented a two-level spondylolysis C5C6. One case was totally asymptomatic and was hazardly discovered. Standard radiographs were used for diagnosis. Conservative treatment was administered in all cases and all patients were immobilized for a few days. DISCUSSION: It has been clearly established that cervical spondylolysis is a congenital disorder often associated with other anomalies: spina bifida, dysplasia of the posterior articular processes. In the child, cervical spondylolysis is only discovered in fifty per cent of Post traumatic cases. The most frequent finding is at C6. A diagnosis can be made based on the radiographs and the CT scan. MRI will only be indicated in spondylolisthesis in order to analyze the disc statement and the degree of canal narrowing. When possible conservative treatment should be adopted. Arthrodesis is reserved for unstable and painful lesions. CONCLUSION: Cervical spondylolysis in the child is a rare congenital disorder. It must be distinguished from the congenital absence of a pedicle and from a pedicle or isthmic fracture. It is a lesion which is normally discovered once the patient has turned adult and is very well long term tolerated.
Percutaneous resection of osteoid osteoma under CT guidance in eight children.
In eight children with suspected osteoid osteoma, a percutaneous resection under CT guidance was performed. The specific drill resection system we currently use includes a 7-mm-diameter toothed drill. Osteoid osteomas were located in the appendicular skeleton in seven children and in the spine (second lumbar vertebral body) in one. All eight patients were successfully treated with complete relief of pain. There was no recurrence of symptoms during a follow-up period of 8-35 months. CT guidance was accurate enough to allow a focal bone excision, and no subsequent bone repair was needed. Histological confirmation was obtained in all cases. This simple and safe technique, when feasible, seems to be an effective means of treatment of osteoid osteoma in children.