[Mechanical properties of human femoral head allografts after physico-chemical treatment (Osteopure)]. / Propriétés mécaniques de greffons humains provenant de têtes fémorales et traitées par un procédé d'épuration physico-chimique (Ostéopure).

PURPOSE OF THE STUDY: Bone grafts and bone substitutes must be biocompatible osteoconductors with satisfactory mechanical properties similar to native bone. When the bone treatment is conducted under specific conditions, the elasticity module under infra-maximal loading can be optimized to achieve reproducible values. The purpose of this work was to determine the effect of the cleaning and sterilization process using Osteopure on the biomechanical properties of trabecular bone harvested from human femoral heads. MATERIAL AND METHOD: Seventy trabecular bone samples were tested: group 1F (fresh samples); group 1N (after application of Osteopure cleaning); group 1S (after Osteopure cleaning and sterilization). Non-destructive and destructive tests (group 1D) were performed. Two fresh femoral heads were used as controls for the destructive test (group 2). The first non-destructive test was applied directly after section (group 1F). Other samples were then purified with Osteopure treatment and a second non-destructive test was conducted (group 1N). A third non-destructive test was conducted after sterilization with 25 kgray radiation (group 1S). Treatments 1 and 2 were performed by OST Developpement SA (Clermont-Ferrand). Finally a destruction test was applied along the directional axis (group 1D). For the 31 samples in group 2 (control) the destructive test was applied along the directional axis immediately after section. Compression tests were performed at a deformation speed of 3 mm/min for 0.3% deformation. RESULTS: The Young module did not exhibit any significant difference between the three steps of the testing in the three orthogonal directions. The Young module was not significantly different between group 1F and group 2 (controls). Maximal force of compression was significantly different (P<0.01). There was a linear relationship between maximal force at rupture and the Young module obtained during destructive tests, for groups 1D and 2 respectively. The compression curves obtained from sterilized samples (group 1D) were not significantly different from those observed for fresh trabecular bone in group 2 (controls). DISCUSSION: The Young module values measured from 70-673 MPa. For non-destructive tests, the module values were to the order of 64% of those obtained for destructive tests. Decreased maximal force of rupture observed for treated samples in comparison with fresh samples can be explained by the extraction of most of the lipids. CONCLUSION: The Osteopure method does not alter stiffness of bone allografts. The elasticity module observed in treated bones is close to that observed in fresh bones. Mechanical resistance to compression is however only half the force of compression observed in the hip joint for daily activities. The linear relationship between the elasticity mode and loading required for rupture is not affected by treatment with Osteopure. The advantages related to elimination of prions or viral contamination appear by far to be more important than the minor changes observed in the mechanical characteristics of allografts.

Contamination by metallic elements released from joint prostheses.

When a metallic implant is in contact with human tissues, the organism reacts and a corrosion process starts. Consequently, we might observe liberation of metallic debris and wear. Our purpose is to measure the contamination and the migration of these metallic elements in the surrounding tissues of the implant. Two types of samples have been studied. First type is sample taken on post-mortem tissues around prostheses to study contamination gradients. Second type is sample taken on pathologic joints on periprosthetic capsular tissues in surgical conditions. These allow estimating contamination degree. The experiments were made on a Van de Graaff accelerator located at CERI (Centre d'Etude et de Recherche par Irradiation, Orléans, France). We measure elemental concentrations resulting from the contamination of the surface of each sample. Results are analysed in function of the pathology and the type of implants. According to the pathology and the location of the sampling, these measurements show a very heterogeneous contamination by metallic elements under particles and/or ionic species which can migrate through soft tissues by various mechanisms.

Normal diameter of the thoracic aorta in adults: a magnetic resonance imaging study.

To determine the evolution of the diameter of the thoracic aorta with age in order to detect dilatation more reliably by imaging, we performed a retrospective analysis of the MRI examinations of the normal thoracic aorta of 66 subjects aged 44.1+/-19.1 years (range 19.1-82.4 years) obtained between 1991 and 2000 on a Magnetom SP 42 1T apparatus (Siemens) using T1-weighted spin echo sequences with electrocardiographic synchronization. Sixteen measurements were made in the axial plane, the oblique sagittal plane in the axis of the aortic arch, and the oblique frontal plane perpendicular to the latter at the level of the ascending aorta, the arch and the descending thoracic aorta. We found an increase in the thoracic aorta diameter and a significant relationship between this diameter and the age of our subjects, wherever the measure was performed. However, there was no systematic correlation between aortic diameter and age. The aortic diameter evolved with age and a marked difference seemed to exist in measurements made in groups younger and older than 40 years. This study, conducted on a small population of 66 patients, thus helps to define a normal aortic diameter, thereby making the diagnosis of pathological dilatation of the aorta more reliable.

[Anatomy of the vestibulo-acoustico-facial neurovascular pedicle. Importance of therapeutic management of vestibular schwannomas]. / Anatomie du pédicule vasculo-nerveux facio-cochléo-vestibulaire. Intérêt dans la prise en charge thérapeutique des schwannomes vestibulaires.

A perfect knowledge of the anatomy of the vestibuloacusticofacial pedicle is required to preserve hearing and facial functions during cerebellopontine angle surgery for vestibular schwannoma. A clarification of the anatomy of this pedicle, in particular of its blood supply, is presented here, based on a review of the available literature, as well as on the author's data issued from anatomical dissections on latex-injected fresh specimens, and from radiological images of the cerebellopontine angle. The blood supply to the vestibuloacusticofacial bundle arises from the meatal loop of the anterior inferior cerebellar artery most often exhibited at the porus of the internal acoustical meatus. The labyrinthine artery is particularly exposed to injury between the cochlear and facial nerves. In addition, dissection in between these two nerves is likely to sever vessels directed to these nerves even though the labyrinthine artery is not interrupted. Thus, aside from a direct injury to the labyrinth, auditory function can be impaired through two distinct ischemic lesion types. Although the facial nerve is supplied through three main arterial systems (from the labyrinthine, the middle meningeal, and the stylomastoid arteries), its labyrinthine portion is more likely to suffer from ischemic damage as it is only supplied by meatal arteries. A refinement of our anatomical knowledge of the vestibuloacusticofacial pedicle, from a functional point of view, could arise from laser Doppler measurements of labyrinthine and facial blood flow during surgery, in an attempt to improve our functional preservation rate during therapeutic procedures for vestibular schwannoma.

[Maximal isometric bite force and sports. Preliminary study]. / Forces occlusales maximales isométriques et sport. Etude préliminaire.

INTRODUCTION: The evaluation of the bite forces coupled with EMG activity of masseter muscles allows to point out temporo-mandibular joint disorders. The intense practice of sports induces stress which may affect the mandibular statics, due to an hyperfunction of the elevator masticatory muscles, especially the masseter muscles. This concept has led us to compare the maximum isometric bite forces of sedentary and physically trained subjects. MATERIAL AND METHODS: The aim of this experimentation is to study the maximum isometric bite forces of the premolars, with a force transducer, for two groups of physically trained and sedentary volunteers (25 subjects), with distinction between male and female subjects. Subjects with normal denture and no temporo-mandibular joint disorder were retained. EMG and force recording were synchronized and recorded during 10 seconds of maximal contraction. RESULTS: The male subjects developed a maximal bite-force significantly higher (p < 0.05) compared to the female subjects. There is no significant difference between subjects practising a sport (at least 6 hours a week) and sedentary ones. The evolution of force during the contraction is different between sexes. EMG activity allowed to control that subjects developed a maximal force and an increase in muscular fatigability of physically active females compared to sedentary ones was noticed. DISCUSSION: The difference of maximal force between men and women is similar to the one found for the locomotor muscles. The analysis of the evolution of the force according to the contraction duration, might be linked to a different distribution of muscular fibers according to the sex. The practice of a sport might increase the fatigability of the masseter muscles and might be a factor inducing a muscular imbalance of the mandibular posture. But the relatively low number of subjects and the absence of well defined distinctions between different kinds of sport limit our conclusions.

[Effect of pelvic member abduction on the kinematics of the thoracic and lumbar spine]. / Influence de l'abduction des membres pelviens sur la cinématique du rachis thoracique et lombaire.

The motion of thoracic and lumbar spine segments has been analysed by mean of the skin landmarks method on 14 volunteers (7 males, 7 females). Results demonstrate that: There is no significant difference between male and female. There is either facilitation, or limitation of the motion of the characteristic landmarks of the spinal segments during trunk motion in perpendicular planes. The mobility of the spinal segments is associated with pelvic girdle motion in order to obtain the planed amplitude, and varies with hips abduction. The analysis of the precise mechanisms of relaxing or stretching of the pelvi-spinal musculo-ligamentous structures constitutes a large field of investigation that necessitates the study of other pelvic limbs postures and needs the use of robotic techniques.

[Prevalence and morphology of pineal cysts discovered at pituitary MRI: review of 1844 examinations]. / Prévalence et morphologie des kystes épiphysaires: à propos de 1844 IRM hypophysaires.

PURPOSE: To evaluate the frequency, morphology and clinical long term evolution of pineal cysts depicted on MRI. PATIENTS AND METHODS: one thousand eight hundred and forty four (1 532 women and 126 men) MRI examinations were retrospectively reviewed. Coronal and sagittal spin echo T1 weighted sequences without and with gadolinium injection were performed, completed with spin echo T2 weighted images when a cystic sellar lesion was suspected. A pineal cyst was diagnosed as a rounded well defined lesion, with fluid signal in an enlarged pineal gland. Follow-up examinations were performed to evaluate the efficacy of the treatment of the sellar lesion. RESULTS: Twenty one epiphyseal cysts (1.27%) were diagnosed in 20 women (1.31%) and one man (0.79%). Their size was 1,2 +/- 0,4 cm (0,3 to 2 cm). They were asymptomatic. In 10 patients, follow-up MRI examinations did not show any change in size. During the clinical follow-up, these twenty-one patients remained asymptomatic (6 months to 5 years). CONCLUSION: The incidental detection of a pineal cyst at MRI is not exceptional. This lesion's pattern appears characteristic and their reputation of benignity is confirmed in our study.

Intrathoracic blood supply of the left vagus and recurrent laryngeal nerves.

The arteries and veins of the left vagus (VN) and left recurrent laryngeal (RLN) nerves from the thoracic inlet to the subaortic region are described following vascular casting with red colored latex in 6 adult fresh non-embalmed cadavers. In all specimens the anterior bronchoesophageal artery supplied at least one vessel to the VN and RLN in the subaortic region. For the RLN other arterial sources were arteries arising from the aortic arch in 1 specimen, the subclavian artery in 3 specimens, the first intercostal artery in 1 specimen, and the inferior thyroid artery in all specimens. For the VN other arterial sources were arteries arising from the aortic arch in 2 specimens and the inferior thyroid artery in 1 specimen. For both the VN and RLN the veins were located under the pleura and directed towards the internal thoracic vein anteriorly and the thoracic intercostal veins posteriorly. In conclusion, the inferior thyroid artery at the thoracic inlet for the RLN and the anterior bronchoesophageal artery are the more consistent vessels supplying the VN and RLN. Vascular damage occurring during mediastinal lymph node excision to the VN and RLN, especially in the subaortic region, may explain postoperative vocal fold paralysis.

Training effects of amortization phase with eccentric/concentric variations--the vertical jump.

The purpose of this study was to find if the performance of the vertical jump is improved by the result of increasing the force, velocity, and muscle adaptation(s). For the experiment, there were four groups (Gr): three groups did the training programs and the fourth group was the control group (CG). In order to establish improvements in force and velocity, the groups performed three variations using eccentric (Ecc) and concentric (Con) movement. Finally, the leg presses, squat jumps (SJ) and countermovement jumps (CJ) were used to determine the changes in the muscle adaptations before and after the training program. For measuring the force, four force transducers were used. In determining the velocity, a displacement transducer was used. A surface EMG was used to measure the muscle activations during all of the tests that were performed. After eight weeks of training, Gr 1 and Gr 2 improved the isometric force and the power during the Con. movement for the leg press. For the SJ, Gr. 1 and 2 increased their height, muscle activity, force, and power, but only group one improved the velocity. However, group three improved the isometric force and power for the leg presses, the squat jump and the countermovement jump. For both of the jumps, they also increased velocity, muscle activity and height. There were no changes observed for group four. Although the three combinations of Ecc/Con movements existed during the training program, the force, velocity and muscle adaptations increased, but not all of the improvements were of the same degree.

Influence of the mode of load carriage on the static posture of the pelvic girdle and the thoracic and lumbar spine in vivo.

The influence of various modes of carrying a load of 16 kg (15.69 DaN) on the static positioning of the pelvic girdle and the thoracic and lumbar segments of the spine was examined in seven male subjects. The displacement of cutaneous markers attached to easily palpable skeletal landmarks was recorded using 4 CCD cameras; the data acquired were analysed using an optoelectronic technique (SAGA3). The subjects stood upright on an AMTI biomechanical force platform, from which the ground reaction forces enabled displacements of the centre of gravity axis and thus the moment of the mass carried to be determined. The modes of load carriage examined were: 1) in a case in the left hand; 2) in a case in the right hand; 3) equally in two cases; 4) on the head; 5) in a rucksack; and 6) in an anterior bag. The results showed displacements of the pelvic girdle, the caudal and cranial lumbar segments, and the caudal and cranial thoracic segments in the three orthogonal planes (sagittal, frontal and transverse). The influence of the moment created by the load was seen in the statokinesigrams. The use of external markers using an optoelectronic technique, in association with the ground reaction forces, enables the mode of load carriage to be determined. The results show that the influence of the moment exerted by the mode of load carriage on the gravity axis has important ergonomic consequences.

[Inguinal hernia in pediatric practice]. / La hernie inguinale en pratique pédiatrique.

Inguinal hernia is a most common pathology in paediatric practice. Diagnosis is usually easy and rarely requires paraclinic exams (sonography). The main risk is strangulation, which can be complicated by testicular or ovarian atrophy. This justifies early surgical treatment. Operative mortality rate is almost nil. There is a risk of recurrence and of occurrence of contralateral hernia.

Visualisation of the portal flows by porto-scanner.

This study presents a retrospective analysis of 15 portal vein CT scans, conducted for the evaluation of hepatic metastasis in patients suffering from colorectal cancer, with the aim of verifying in vivo the presence of laminar flow as reported by Pironcof. After selective catheterization of the superior mesenteric artery, CT scans were performed during opacification of the portal vein. Different flows were identified by the incomplete opacification they induced in the portal vein. Splenic flows could always be identified, however right colic and superior mesenteric flows were only seen in 3 cases (20%) and gastrocolic flow in 2 (13.6%). Even though incremental (i.e. slower than helical) the CT acquisitions allowed the flows to be viewed by modifying the visualisation window. In vivo evidence of laminar flow is provided which supports Pironcof's experimental observations.

[Abduction of pelvic members and pelvic girdle kinematics]. / Abduction des membres pelviens et cinématique de la ceinture pelvienne.

The analysis of the displacement of the pelvic girdle, during movements of the trunk in the anatomical orthogonal plans, was carried out by the technique of the cutaneous markers on two series of 7 male subjects and 7 female. The photographs made it possible to objectify angular displacements of reliable singular points and to observe that the abduction of hips determines, according to movements carried out, either a facilitation, or a limitation of displacements observed similar in the two series. The precise mechanism of these variations will have to be analyzed by later studies.

The effect of loads carried on the shoulders.

This work describes a way of measuring the forces acting on the shoulders when subjects carry a backpack. A frame pack was carried by 12 male subjects: 4 hikers, 4 occasional hikers, and 4 novices. They walked for 30 minutes on a 5% inclined treadmill at 3.6 km/h to simulate moderate hiking. The load was carried at T9 and was increased (10, 15, and 20 kg) after 1, 20, and 25 minutes. The data from force transducers placed on the shoulder straps were collected for 30 seconds at 100 Hz. Shoulder strain appeared to be the limiting factor in load carriage. The optimal carrying method depends on the person, but it has been shown that decreasing stride length and wearing appropriate footwear reduces the strain on the shoulders.

Changes of contour of the spine caused by load carrying.

The development of new leisure activities such as walking has spread the use of the backpack as a means of carrying loads. The aim of this work was to present a way of defining the movements imposed on the trunk by this type of load carrying. A 20 kg load situated at the thoracic level (T9) of the trunk, was placed in a backpack (2.5 kg). The 12 subjects were average mountain guides of Auvergne region, intermediate level and complete beginners. External markers were glued to the projecting contours of the spinous processes of the C7, T7, T12, L3 and S1 vertebrae, the shin and the external occipital tuberosity (EOT). Using a Vicon 140 3-D system we measured the effective mobility of the different spinal segments in the sagittal plane during one step. For every subject, we noticed a significant decrease of the effective inter-segmental mobility (EISM) between S1-L3-T12 (p < .01) while backpacking a 22.5 kg load. A decrease of EISM also appeared at the next level between L3-T12-T7 (p < .05). An increase of the EISM between T7-C7-EOT was noted (p < .05). We supposed that strength loss of the back muscles and/or angular oscillations of the trunk could be a common cause of symptoms during backpacking. The subjects using this type of load carrying have to adopt an adequate position of the lumbar, dorsal and cervical vertebrae.

[Radio-anatomic study of the angle of origin of dysplastic renal arteries]. / Etude radio-anatomique de l'angle d'origine des artères rénales dysplasiques.

PURPOSE: To compare the angulation at the origin of dysplastic renal arteries compared to atherosclerotic renal arteries, in order to improve the technique for percutaneous transluminal angioplasty of FMD. MATERIALS AND METHODS: Retrospective analysis of 40 aortograms in patients who underwent renal angioplasty for dysplastic stenosis, with comparison with 45 control aortograms (with or without atherosclerotic lesions of the renal arteries). The angle of implantation of the renal arteries was measured relative to the aortic axis in the frontal plane, taking into account only the angulation of its proximal segment. We identified three types of kidneys with regard to their position relative to the renal artery ostium. RESULTS: The angle of implantation of dysplastic renal arteries is significantly sharper compared with the control group (63.8 degrees vs 80.9 degrees, p = 0.0001), irrespective of the side. The angulation did not correlate with the position of the kidney or the direction of the renal artery, suggesting a congenital origin. CONCLUSION: The angle of implantation of the dysplastic renal arteries relative to the aortic axis in the frontal plane is sharper than the angle measured in non dysplastic renal arteries.

Determination of metallic ion transfer from an implanted prosthesis by the PIXE method.

Prostheses can release some metallic elements to the surrounding tissues, particularly when they are not covered with a biomaterial layer and when an unsealing process happens. We try to measure major and trace elements in these tissues with an experimentally sensitive method. Proton-induced X-ray emission is used to detect about 10 elements in tissue. Tissues are calcinated and deposited in a thin layer before irradiation. Results are obtained in a standard and samples from three patients. We observe contamination by Ti, Cr, Ni, and Zn in the tissues. Correlations are to be studied between these atomic transfers and prosthesis in the patient.

Role of hip abduction in the kinetics of the thoracic and lumbar spine.

The motion of the thoracic and lumbar spine segments was analysed by mean of the skin landmarks method in 14 volunteers (7 males, 7 females). The results demonstrated that there was no significant difference between men and women and there was either facilitation or limitation of the motion of the characteristic landmarks of spinal segments during trunk motion in perpendicular planes. The mobility of spinal segments was associated with pelvic girdle motion in order to obtain the planned amplitude, and varied with hip joint abduction. The analysis of the precise mechanisms of relaxing or stretching of the pelvivertebral musculo-ligamentous structures constitutes a large field of investigation that necessitates the study of other lower limb postures and the use of robotic techniques.

Determination of the position of the pelvic girdle using surface markers.

The overall movement of the trunk is made up of two components, namely the movements of the pelvic girdle and the vertebrae. In the frontal plane, the amplitude of the pelvic movements appears to be relatively limited compared to the vertebral column whereas the pelvis makes the major contribution to the total rotational movement in the axial plane.