Biomedical subjects

D Gignac

Publications and source records attributed to D Gignac.

12 recordsLinked to original sources

PubMed2000

Optimization method for 3D bracing correction of scoliosis using a finite element model.

Scoliosis is a complex three-dimensional deformity of the spine and rib cage frequently treated by brace. Although bracing produces significant correction in the frontal plane, it generally reduces the normal sagittal plane curvatures and has limited effect in the transverse plane. The goal of this study is to develop a new optimization approach using a finite element model of the spine and rib cage in order to find optimal correction patterns. The objective function to be minimized took account of coronal and sagittal offsets from a normal spine at the thoracic and lumbar apices as well as the rib hump. Two different optimization studies were performed using the finite element model, which was personalized to the geometry of 20 different scoliotic patients. The first study took into account only the thoracic deformity, while the second considered both the thoracic and lumbar deformities. The optimization produced an average of 56% and 51% reduction of the objective function respectively in the two studies. Optimal forces were mostly located on the convex side of the curve. This study demonstrates the feasibility of using an optimization approach with a finite element model of the trunk to analyze the biomechanics of bracing, and may be useful in the design of new and more effective braces.

Adolescent↗

PubMed1999

Variability of strap tension in brace treatment for adolescent idiopathic scoliosis.

STUDY DESIGN: A mechanical evaluation of brace strap tensions to document their variability in different patient positions and to assess their biomechanical effectiveness. OBJECTIVES: To measure the strap tensions at which adolescents with scoliosis are wearing their braces and to determine the variations in strap tension in different patient positions. SUMMARY OF BACKGROUND DATA: The biomechanical action of thoracolumbosacral orthoses in still not well understood, and there is no standardized strap tension at which the brace should be fastened to obtain optimal results. METHODS: This study was conducted in 34 adolescents with idiopathic scoliosis wearing thoracolumbosacral orthoses. Brace straps were instrumented with load cells and tightened at four tensions (the ones prescribed by their treating physician and three standardized values: 20, 40, and 60 N). In each case, the tension was recorded while the patients assumed nine positions corresponding to normal daily tasks. The variability of strap tension was evaluated by comparing the changes from the original standing position. RESULTS: The prescribed tensions measured in thoracic and pelvic straps were markedly variable. The greatest changes in tension occurred when the patients were lying down. Relaxation of strap tension was found when the patients returned to the standing position after having completed the tasks. CONCLUSIONS: If strap tension affects the biomechanical actions of the brace, these results indicate that regular brace strap tension adjustments are needed and raise questions about the efficacy of nighttime bracing to correct spinal deformities.

Adolescent↗

PubMed1998

[A biomechanical study of new orthotic treatment approaches for the 3D correction of scoliosis].

Scoliosis is a complex deformity of the spine and rib cage often treated by the Boston brace. The goal of this research is to study the simulation of two new treatment approaches and to compare their results to the Boston brace. A personalized biomechanical model has been used to simulate the treatment on 20 scoliotic teenagers with double curvature. On the first treatment, different forces were applied at the thoracic apex level and the posterior displacement of the rib hump was locked. For the second treatment, an oblique force oriented 45 degrees with respect to the frontal plane was added at the lumbar apex. Following each simulation, geometrical and clinical measurements were calculated and compared to the initial geometry and the Boston brace treatment. Overall, the two new treatment modalities correct the thoracic Cobb angle in the frontal plane while maintaining the normal physiological curvatures in the sagittal plane, move the thoracic plane of maximum deformity towards the sagittal plane and reduce axial rotation and rib hump. In comparison, the Boston brace reduces the Cobb angles in the frontal as well as in the sagittal planes, moves the planes of maximum deformities towards the coronal plane and has no effect on axial rotation and rib hump. This biomechanical study shows force patterns that correct scoliosis more efficiently than the Boston brace. These new treatment approaches must be personalized for each patient and still require clinical evaluation.

Adolescent↗

PubMed1994

[Acute post-rhinoplasty dacryocystitis. Apropos of a case].

Lacrimal ducts are exposed to surgical wounds during cosmetic surgery of the nose because of the anatomic situation. Beside minor and transitory injuries exist major injuries needing a surgical solution. The authors report a case of an acute dacryocystitis after an aesthetic rhinoplasty. After reviewing the literature and studying the possible traumatic mechanisms, the authors propose to treat the lacrymal injury by a bicanaliculonasal intubation before than performing a dacryocystorhinostomy.

Acute Disease↗

PubMed1994

Microfiberoptic evaluation of the middle ear cavity.

Endoscopic instruments have revolutionized surgical diagnosis and treatment. Recently, a high resolution microfiberoptic endoscope has been developed that has vast potential for otologic use. This microfiberoptic endoscope was used in cadaver and human studies to visualize the middle ear cavity. The technique used involved placing a 1.0-mm or smaller microfiberoptic scope into the middle ear via a tympanic membrane perforation, through a myringotomy tube or up the eustachian tube. Using the scope, the mesotympanum and hypotympanum can be well visualized. Similarly, the round window, oval window, ossicular chain, and related structures can be clearly demonstrated and recorded photographically. This technique has great potential to enhance diagnosis without open surgery.

Adolescent↗

PubMed1993

MRI exploration of the intrapetrous facial nerve.

We report our experience of intrapetrous facial nerve evaluation in 33 patients examined by three-dimensional MRI (3D-FT) with intravenous gadolinium injection. The examinations were performed by a 1 Tesla magnet, using Flash and Turbo-Flash sequences which enabled us to obtain contiguous millimetric sections and to make reconstructions in all planes. Among these 33 patients, 31 had facial palsy and 2 a facial nerve lesion without clinical signs and discovered by chance. Facial palsy had started rather abruptly in 26 cases. It was either idiopathic (n = 20) or caused by herpes zoster (n = 1), injuries (n = 2), metastasis (n = 1) and tumour (n = 1); it was concomitant with a granuloma in 1 case. Five patients seen or explored late had congenital cholesteatoma (n = 2), facial nerve neurinoma (n = 2) or persistent idiopathic facial palsy (n = 1). There was no contrast enhancement in "chronic" non tumoral facial palsy. All tumours (neurinoma, neurofibroma, metastasis) were contrast-enhanced, as were the 2 cases of traumatic palsy and the case with granuloma of the labyrinth. In acute idiopathic facial palsy (n = 20), contrast enhancement was demonstrated in 11 patients; among these, recovery was complete at 2 months in 1 case and incomplete in 9 cases; 1 patient was lost sight of. In the 9 patients without contrast enhancement, recovery was complete in 7; 2 patients were lost sight of. This study shows that minute lesions of the facial nerve can be detected with millimetric MRI T1-weighted sequences and contrast enhancement. It also suggests that contrast enhancement has some prognostic value in patients with acute idiopathic facial palsy.

Acute Disease↗

PubMed1991

Willingness of nursing students and faculty to care for patients with AIDS.

Previous research has indicated that nursing students, along with other health care professionals, have expressed an unwillingness to care for patients with AIDS. The purposes of this study were to examine the relationships among nursing students' and faculty members' knowledge of AIDS, attitudes toward patients with AIDS, and willingness to care for them. A descriptive-correlational design was used in which nursing students and faculty (n = 166) at an urban, middle-sized Canadian university completed the AIDS Assess Test developed by Lawrence and Lawrence. Significant relationships were found between willingness to care for and have contact with persons with AIDS and knowledge scores for the group as a whole. Nursing students with more knowledge about AIDS expressed greater willingness to care for AIDS patients. Subjects in the senior year of the nursing program had significantly higher scores on willingness to care for or have contact with persons with AIDS than subjects in other levels of the program and faculty (F(4, 143) = 2.94, p = 0.02). Subjects who knew a homosexual person had significantly higher scores on willingness to care for and have contact with persons with AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Knowledge and attitudes about AIDS among Canadian nursing students: educational implications.

Research was conducted to examine the level of knowledge and attitudes about acquired immunodeficiency syndrome (AIDS) among Canadian nursing students and faculty and the relationships among knowledge, attitudes, and willingness to care for AIDS patients. The study was an extension of earlier research by Lawrence and Lawrence (1989). A descriptive-correlational design was used in which four levels of nursing students and faculty (N = 166) completed the AIDS Assess Test. Knowledge scores increased as students progressed through the program; faculty had the highest scores. Attitude scores were relatively low, indicating areas in which further education and values clarification are essential. Pearson's r revealed significant positive relationships between subjects' knowledge of AIDS and attitude scores for the sample as a whole and two levels of students in the nursing program. Other variables relating to subjects' attitudes toward AIDS patients and willingness to care for and have contact with them were identified in the research. Findings suggest additional learning experiences for assisting students in developing the knowledge needed for care of the patient with AIDS and clarifying values and beliefs which might influence that care.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Vestibular neurotomy by retrosigmoid approach: technique, indications, and results.

During the past 15 years, 96 retrosigmoid vestibular neurotomies have been used in the surgical management of incapacitating Meniere's disease for the control of vertigo and preservation of hearing. This posterior approach of the pontocerebellar angle gives the best view on the acousticofacial nerve bundle, through a 2 x 2 cm suboccipital craniotomy immediately behind the mastoid and sigmoid sinus. Then the vestibular nerve is easily identified, separated from the cochlear nerve and sectioned, the facial nerve not being at risk, as it lies much deeper. Actually, the majority of authors agree that vestibular neurotomy is the most effective surgical treatment in relieving disabling vertigo (96% of cases) with serviceable hearing, but few surgeons know that the retrosigmoid approach is simpler and more reliable than the middle fossa or retrolabyrinthine approaches, with a low incidence of complications. The purpose of this paper is to emphasize the routine use of the retrosigmoid approach.

Aged↗

PubMed1990

[Otospongiosis: different surgical technics, identical results. Why?].

Both platinectomy and platinotomy are currently used to treat otosclerosis surgically. Though the techniques are different from one another, especially by the new area ratio between tympanic membrane and stapes foot-plate, the results are similar. It should be clear that the simple "piston model" of the tympanic ossicular system cannot explain this results. If, for the seesaw mechanical view, a vibratory molecular system conducting acoustic energy is substituted, a pertinent explanation can be given for this result. Thus, understanding of the pattern motion of the tympanic ossicular system has to change drastically.

Ear, Middle↗

PubMed1990

[Retraction pockets, pathological entity?].

Retraction pockets are not a pathological entity per se but take after various ear diseases, with which they share the same morphological eardrum alterations. The authors believe that any holistic evaluation of retraction pockets, as though these were forming a single group of like pathogenic origin, i.e., tubal dysfunction, would be artificial and raise therapeutic problems. The statistical analysis of the causes for retraction pocket formation provides little information. Otologists are still looking into chronic otitis media and cholesteatoma as a possible, long-suspected, unproved etiology. Electron microscopy and, more particularly, istological-enzymological analyses of mounts prepared by the authors have shown, in some cases, the anomalous presence, in the pocket, of Langerhans' cells, which the authors consider as strongly indicative of cholesteatoma. While confirming the clinical diagnosis, anatomopathological examination allows to differentiate poor-prognosis retraction pockets from benign ones. The pathogenesis of these pockets is still poorly understood. It is the authors' contention that tympanic invagination is more likely traceable to some biopathological/biochemical phenomenon than to occupational mechanical disorders involving the tube. The clinical characteristics of retraction pockets are the basis for their classification into three groups, according to their evolutional tendency. Thus, developing cholesteatomas bear a poor prognosis; sequelae of benign otitis are associated with small risk; lastly, there is a small group of pockets the evolution of which is hard to specify. The authors believe that such differentiation between retraction pockets is mandatory to have a clear picture of therapeutic indications, and to assess the various outcomes.

Cholesteatoma↗

PubMedDate not supplied

Jordanian and Canadian nursing students' knowledge about AIDS.

With the current HIV/AIDS epidemic unchecked and as yet no known cure or vaccine, it is critical that students be prepared to care for AIDS patients. Thus nursing schools must teach them full data on the disease, prevention and universal precautions.

Acquired Immunodeficiency Syndrome↗