10 research outputs found
Study and examination of the implements used for securing pelvis bone
Our goal was to compare the direct plate known as the “gold standard” technology in case of a pelvis fracture with the H-plate technology reinforced with iliolumbar fusion and the pelvis screwing technology reinforced with iliolumbar fusion, especially focusing on the matter of stability.In our work we studied and examined the securing possibilities and stability of the transforaminal pelvis fracture using the finite element analysis. My colleauges and I created the anatomically correct model (including the 4th and 5th lumbars and cartilages under the lumbars). To create the model we used a previous geometric model used for older preceding analyses. During the modeling we perfected the geometry; we separated the different bone regions and paid close attention to create the scale model of the implements. The placements of the implements are appropriate and in accordance with real surgery procedures. We examined three different cases: standing on the healthy leg, standing on both legs and standing on the injured leg. The boundary conditions for the finite element analysis: the femur is fi xed and in case of standing on one leg the opposing side of the hip bone is fixed on both the X and Z axes directions. Furthermore both hip bones are fixed on the Y axis direction, and this applies when standing on both legs as well. We added the load to the 4th lumbar on the model. The value of the load is 500 N and the direction is –Z. We defined surface to surface connection between the femur and acetabulum and also between the side of the symphysis pubica and the fracture ends. We defined bonded connection between all the other components. In our analyses and evaluation we examined the arising stress values and also the displacements in the cortical and spongiosa regions and in the implements. We examined the elongation of the ligaments in the pelvis and measured the maximal distance between the fracture ends under load.Considering the results of the stress states, the iliolumbar fusion technologies provide more stability. Therefore it is recommended to use these technologies, not mentioning the fact that the dorsal exposure puts the patient through considerably less trauma.Considering the results of the fracture ends displacements it can be declared that the reason for the existence of the H-plate technology reinforced with iliolumbar fusion cannot be questioned. Therefore continuing the research can be justifi ed by further analyzing and examining dynamic loads on models extracted from CT images. DOI: 10.17489/biohun/2010/1/2
Medencegyűrű-sérülések műtéti rögzítésének végeselemes modellezése
A vertikálisan és rotációban is instabil C típusú medencegyûrû-sérülések rögzítésére használt különbözõ lemezes rögzítési technikák stabilitási vizsgálata az általunk kidolgozott végeselemes medencemodellen. Két lábon állás mellett C típusú medencegyûrû-sérülést hoztunk létre úgy, hogy Denis I., illetve Denis II. keresztcsont (sacrum) törést és a szeméremcsonti ízület szakadását (symphyseolysist) modelleztünk. A symphyseolysist 4 lyukas rekonstrukcióslemezzel, a Denis I. sacrumtörést 2 db 2 lyukas rekonstukciós lemezzel stabilizáltuk a kismedence felõl (ventralisan), majd az általunk használt transsacralisan, hátulról (dorsalisan) felhelyezett keskeny, illetve széles DC-lemezzel. A Denis II. sacrumtörést ventral felõl ugyancsak2 db 2 lyukas rekonsrukciós lemezzel fixáltuk, majd dorsal felõl KFI-H-lemezes rögzítést modelleztünk. A végeselemes modellezés ALGOR programmal történt. A medencét alkotó csontok mellett az ízületeket és a mechanikai szempontból jelentõs szalagokat is modelleztük. A modell validálása megtörtént, párhuzamosan végzett hullai csont-szalagos preparátumokon végzett mérési eredményekkel. A törési rés két oldala közötti elmozdulást, valamint a rögzítõfémekben és a környezõ csontokban fellépõ feszültségeket mértük. A transsacralis lemezes synthesis mellett nagyobb elmozdulások mérhetõk, mint direkt lemezes rögzítés esetén. A KFIH-lemezekkel végzett mûtét stabilitása a direkt lemezes és a transsacralis lemezes synthesis stabilitása között van. Az eredmények korrelálnak a párhuzamosan elvégzett csont-szalagos hullai medencepreparátumokon végzett mérések eredményeivel. A végeselemes modell alkalmas a fentleírt sérüléseket rögzítõ synthesisformák összehasonlítására. Mivel a cadaver-preparátumokon végzett vizsgálatok számos nehézségbe ütköznek, a modell használatának létjogosultságavitathatatlan.A vertikálisan és rotációban is instabil C típusú medencegyûrû-sérülések rögzítésére használt különbözõ lemezes rögzítési technikák stabilitási vizsgálata az általunk kidolgozott végeselemes medencemodellen. Két lábon állás mellett C típusú medencegyûrû-sérülést hoztunk létre úgy, hogy Denis I., illetve Denis II. keresztcsont (sacrum) törést és a szeméremcsonti ízület szakadását (symphyseolysist) modelleztünk. A symphyseolysist 4 lyukas rekonstrukciós lemezzel, a Denis I. sacrumtörést 2 db 2 lyukas rekonstukciós lemezzel stabilizáltuk a kismedence felõl (ventralisan), majd az általunk használt transsacralisan, hátulról (dorsalisan) felhelyezett keskeny, illetve széles DC-lemezzel. A Denis II. sacrumtörést ventral felõl ugyancsak 2 db 2 lyukas rekonsrukciós lemezzel fixáltuk, majd dorsal felõl KFI-H-lemezes rögzítést modelleztünk. A végeselemes modellezés ALGOR programmal történt. A medencét alkotó csontok mellett az ízületeket és a mechanikai szempontból jelentõs szalagokat is modelleztük. A modell validálása megtörtént, párhuzamosan végzett hullai csont-szalagos preparátumokon végzett mérési eredményekkel. A törési rés két oldala közötti elmozdulást, valamint a rögzítõ fémekben és a környezõ csontokban fellépõ feszültségeket mértük. A transsacralis lemezes synthesis mellett nagyobb elmozdulások mérhetõk, mint direkt lemezes rögzítés esetén. A KFIH-lemezekkel végzett mûtét stabilitása a direkt lemezes és a transsacralis lemezes synthesis stabilitása között van. Az eredmények korrelálnak a párhuzamosan elvégzett csont-szalagos hullai medencepreparátumokon végzett mérések eredményeivel. A végeselemes modell alkalmas a fent leírt sérüléseket rögzítõ synthesisformák összehasonlítására. Mivel a cadaver-preparátumokon végzett vizsgálatok számos nehézségbe ütköznek, a modell használatának létjogosultsága vitathatatlan. DOI: 10.17489/biohun/2008/1/3
Eklem Hastalıkları ve Cerrahisi Does surgically fixation of pubic fracture increase the stability of the operated posterior pelvis? Pubis kırığının cerrahi tespiti ameliyat edilen arka pelvisin stabilitesini artırır mı?
Joint Diseases and Related Surgery Experimental Study / Deneysel Çalışma Anahtar sözcükler: Sonlu eleman analizi; pelvis halkası; pubis kırığı; pubis plağı; retrograde pubis vidası. Objectives: This study aims to investigate whether surgical treatment of pubic rami fractures increases the stability of the posterior pelvis. Material and methods: A finite element pelvic model with improved geometric and material characteristics was analyzed. By imitating a standing position, a type I Denis sacrum fracture and a unilateral pubis fracture, we measured the differences in tension and displacement. The posterior injury was treated with a direct plate synthesis or transsacral plate synthesis, while the pubis fracture was left without fixation or fixed with either a retrograde pubic screw or plate synthesis. Results: The operative fixation of pubic rami fractures decreased the movement in the fracture gap not only at the site of the pubis fracture, but also at the site of the fixed sacrum fracture. The plate synthesis provided greater stability of the anterior fracture than the retrograde screw. The tensions in the implants were below the allowed values. Conclusion: We concluded that surgically fixation of pubic fracture increases the stability of the operated posterior pelvis
Delayed Spinal Cord–Brachial Plexus Reconnection after C7 Ventral Root Avulsion: The Effect of Reinnervating Motoneurons Rescued by Riluzole Treatment
Delayed Spinal Cord–Brachial Plexus Reconnection after C7 Ventral Root Avulsion: The Effect of Reinnervating Motoneurons Rescued by Riluzole Treatment
Accounting for radiation exposure from previous CT exams while deciding on the next exam: What do referring clinicians think?
© 2022 Elsevier B.V.Purpose: To obtain clinicians’ views of the need to account for radiation exposure from previous CT scans and the advisability of a regulatory mechanism to control the number of CT scans for an individual patient. Methods: A convenience survey was conducted by emailing a link to a three-question electronic survey to clinicians in many countries, mostly through radiology and radiation protection contacts. Results: 505 responses were received from 24 countries. 293 respondents (58%) understand that current regulations do not limit the number of CT scans that can be prescribed for a single patient in a year. When asked whether there should be a regulation to limit the number of CT scans that can be prescribed for a single patient in one year, only a small fraction (143, 28%) answered ‘No’, 182 (36%) answered ‘Maybe’ and 166 (33%) answered ‘Yes’. Most respondents (337; 67%) think that radiation risk should form part of the consideration when deciding whether to request a CT exam. A minority (138; 27%) think the decision should be based only on the medical indication for the CT exam. Comparison among the 4 countries (South Korea, Hungary, USA and Canada) with the largest number of respondents indicated wide variations in responses. Conclusions: A majority of the surveyed clinicians consider radiation risk, in addition to clinical factors, when prescribing CT exams. Most respondents are in favor of, or would consider, regulation to control the number of CT scans that could be performed on a patient annually.N
Accounting for radiation exposure from previous CT exams while deciding on the next exam: What do referring clinicians think?
Purpose: To obtain clinicians’ views of the need to account for radiation exposure from previous CT scans and the advisability of a regulatory mechanism to control the number of CT scans for an individual patient. Methods: A convenience survey was conducted by emailing a link to a three-question electronic survey to clinicians in many countries, mostly through radiology and radiation protection contacts. Results: 505 responses were received from 24 countries. 293 respondents (58%) understand that current regulations do not limit the number of CT scans that can be prescribed for a single patient in a year. When asked whether there should be a regulation to limit the number of CT scans that can be prescribed for a single patient in one year, only a small fraction (143, 28%) answered ‘No’, 182 (36%) answered ‘Maybe’ and 166 (33%) answered ‘Yes’. Most respondents (337; 67%) think that radiation risk should form part of the consideration when deciding whether to request a CT exam. A minority (138; 27%) think the decision should be based only on the medical indication for the CT exam. Comparison among the 4 countries (South Korea, Hungary, USA and Canada) with the largest number of respondents indicated wide variations in responses. Conclusions: A majority of the surveyed clinicians consider radiation risk, in addition to clinical factors, when prescribing CT exams. Most respondents are in favor of, or would consider, regulation to control the number of CT scans that could be performed on a patient annually. © 2022 Elsevier B.V