Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 6 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 4 uppsatser.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--University of Tennessee Health Science Center, 2008. / Title from title page screen (viewed on February 24, 2009). Research advisor: Denis DiAngelo Ph.D. Document formatted into pages (viii, 59 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 42-46).

The history of total knee arthroplasty stretches back over 70 years. Many studies have shown that TKA is, in general, a successful operation for the relief of joint pain, with patient satisfaction rates of 90-95% and implant survival rates at 10-15 years of greater than 90%. However, a number of studies have also shown the potential for failures or complications arising post-implantation leading to revision surgery. This thesis presents finite element (FE) models of the distal femur following primary and revision total knee arthroplasty. Pre-arthroplasty models are also developed for comparison. Particular attention is given to how femoral component design and method of fixation impacts the mechanical environment of the distal femur and stability of the prosthesis. FE analyses with fully bonded interfaces indicate that femoral components are subject to areas of low stress (stress shielding) immediately under the anterior flange and chamfer regardless of internal implant features. However, internal implant features were found to play a role in the pattern and magnitude of stress concentrations. Both stresses and motions were observed to increase with increasing flexion angle, indicating the importance of testing at multiple angles. The initial models of the distal femur were extended to incorporate the effects of ageing and endosteal thinning of the femoral cortex, through novel application of pre-existing FE modelling techniques, specifically the ability to assign variable material properties corresponding to the nodal temperatures output from a heat transfer analysis. The findings from this study indicate that older patients with osteoporosis may be at increased risk of periprosthetic fracture compared to younger healthy patients. The use of a revision femoral component with a cemented stem as a means to mitigate this fracture risk was also investigated. FE analyses using frictional interfaces were employed to determine the influence of femoral component design on micromotion at the interface. These models showed that all primary implants were subject to similar magnitudes of relative motion at the interface, however, the distinct internal implant features led to very different regional variations. Furthermore, certain internal implant features (i.e. femoral box) were found to be highly sensitive to errors in surgical bone cuts. This aspect of the thesis also concluded that the addition of a stem served to significantly reduce motions at the interface in comparison to primary stemless implants. Long stemmed prostheses were found to result in the smallest levels of interface motion. This study also detailed the design and creation of an in vitro test setup for the purposes of determining the influence of stem length and fixation on the stability of revision prostheses. Experimental results using this test rig showed that a cemented short stem provides as much initial stability as the uncemented long stem, and is easier to fit surgically. Corresponding FE models incorporating a virtual representation of the test rig and in vitro loading conditions revealed that the relative motion at the multi-planar bone-prosthesis interface cannot be adequately described using a single reference point. However, in vitro setups may be used to predict a general measure of implant stability and to provide a source of calibration for FE. The distal femur models were further modified to investigate how the presence of condylar defects as classified by AORI defect classification system (Engh 2006) and weak osseous support due to osteoporosis may adversely affect the survival of the prosthesis. These investigations revealed that fixation of the femoral component, the presence of a large condylar defect and the level of osseous support all had an impact on stress in the implant, it is concluded that a non-modular approach should be adopted in older patient groups with severe osteoporosis to mitigate the risk of component junction failure and distal femoral fracture.

Made available in DSpace on 2014-11-10T11:09:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-07Bitstream added on 2014-11-10T11:57:29Z : No. of bitstreams: 1 000785278.pdf: 9323801 bytes, checksum: f9990068cf96a193d90d9cb627dc3c41 (MD5) / Objetivos: Avaliar, através de um estudo clinico, randomizado, controlado e cego, a eficácia do plasma rico em plaquetas na cicatrização, dor e hemostasia após artroplastia total do joelho. Metodologia: Foram selecionados 40 pacientes que seriam submetidos a prótese total do joelho e randomizados. Em 20 destes pacientes foi aplicado o plasma rico em plaquetas antes do fechamento da cápsula articular. Foram realizadas dosagens de hemoglobina (mg/dL) e hematócrito (%) no pré-operatório, após 24 e 48 horas da cirurgia. Aplicado o questionário WOMAC, a escala verbal da dor e medidas as amplitudes de movimento do joelho até o 2o mês pós-operatório. A análise estatística comparou os resultados afim de comprovar haver diferença entre os grupos em cada um dos momentos da avaliação. Resultados: Medidas do valor da hemoglobina (mg/dL) e hematócrito (%) realizadas no pré-operatório, após 24 e 48 horas da cirurgia não mostraram diferenças significativas entre os grupos (p>0,05). O questionário WOMAC e a amplitude de movimento medidas no pré-operatorio e até os dois primeiros meses também não mostraram diferenças estatísticas entre os grupos (p>0,05). A avaliação da dor através da escala verbal, mostrou vantagem no grupo que utilizou o plasma rico em plaquetas após 24 e 48 horas, uma e três semanas e dois meses de pós-operatório (p<0,05). Conclusões: Da maneira que foi utilizado, o plasma rico em plaquetas não se mostrou efetivo para reduzir sangramento ou melhorar a função do joelho após a artroplastia em comparação aos controles. Houve vantagem na escala verbal de dor pós-operatória. Descritores: Artroplastia, joelho, transfusão, plasma rico em plaquetas, sangramento / Purpose: To assess, through a clinical study, randomized, controlled ande singleblinded, the effectiveness of platelet-rich plasma in healing, pain and hemostasis after a total knee arthroplasty. Methods: 40 patients, that would be submitted to total knee arthroplasty, were selected and randomized. In 20 of these was applied platelet-rich plasma before the closure of the joint capsule. Hemoglobin and hematocrit levels were measured in the preoperative, after 24 and 48 hours of surgery. The WOMAC questionnaire and verbal pain scale were applied, measures of the range of motion of the knee were performed until the second postoperative month. Statistical analysis compared the results in order to prove if there is a difference between the groups at each time of evaluation times. Results: Hemoglobin and hematocrit levels performed preoperatively, after 24 and 48h of surgery showed no significant differences between groups (p>0,05). The WOMAC questionnaire and the measures of range of motion in the preoperative and even in the first two months also showed no statistic differences between groups (p>0,05). Pain assessement through verbal scale showed benefit in the group using platelet-rich plasma after 24 and 48 hours, one to three weeks and two months postoperative (p<0,05). Conclusions: The way it was used, the platelet-rich plasma was not effective for reducing bleeding or improve knee function after arthroplasty compared with controls. There was an advantage in the verbal scale of postoperative pain

Em um estudo prospectivo e randomizado sobre o posicionamento do componente acetabular na artroplastia total do quadril, 20 quadris foram operados com o auxílio da navegação livre de métodos de imagem e 20 quadris foram operados através do método convencional. Todas as cirurgias foram realizadas pelo mesmo cirurgião com o paciente em decúbito lateral. A avaliação do posicionamento foi feita através da medição tomográfica pós-operatória dos ângulos de anteversão e inclinação cirúrgicos e análise da zona de segurança. Os resultados obtidos foram similares em todas as comparações: anteversão média de 17,4o no grupo navegado e 14,5o no grupo convencional (p=0,215), inclinação média de 41,7o no grupo navegado e 42,2o no grupo convencional (p=0,633), desvio médio do objetivo da anteversão (15o) de 5,5o no grupo navegado e 6,6o no grupo convencional (p=0,429), desvio médio do objetivo da inclinação (40o) de 3o no grupo navegado e 3,2o no grupo convencional (p=0,783) e localização dentro da zona de segurança de 90% no grupo navegado e 80% no grupo convencional (p=0,661). A avaliação tomográfica pós-operatória do posicionamento acetabular na artroplastia total de quadril realizada com o paciente em decúbito lateral foi semelhante ao se comparar a técnica navegada com a técnica convencional / In a prospective and randomised study of the acetabular component position in total hip arthroplasty, 20 hips were operated using imageless navigation and 20 hips were operated using the conventional method. The same surgeon performed all the operations with the patient in the lateral position. The correct position of the acetabular component was evaluated with computed tomography performed after the surgeries, measuring the operative anteversion angle and the operative inclination angle and determining the cases inside the safe zone. The results were similar in all the analyses: a mean anteversion of 17.4o in the navigated group and 14.5o in the conventional group (p=0.215), a mean inclination of 41.7o in the navigated group and 42.2o in the conventional group (p=0.633), a mean deviation from the desired anteversion (15o) of 5.5o in the navigated group and 6.6o in the conventional group (p=0.429), a mean deviation from the desired inclination (40o) of 3o in the navigated group and 3.2o in the conventional group (p=0.783), and location inside the safe zone of 90% in the navigated group and 80% in the conventional group (p=0.661). The acetabular component positions tomography analyses in total hip arthroplasty, performed with the patient in the lateral position, were similar whether using imageless navigation or performing it conventionally

Introdução: As alterações anatômicas do fêmur proximal ou do acetábulo, como as decorrentes das sequelas da epifisiólise do fêmur proximal, da displasia do quadril da doença de Legg-Perthes-Calvé, podem levar ao desenvolvimento da artrose do quadril. No entanto, em torno de 80% dos indivíduos que desenvolvem essa doença têm uma anatomia óssea considerada normal. Ainda assim, surgiu a hipótese que alterações sutis do fêmur proximal ou do acetábulo, denominadas, respectivamente, cam e pincer, poderiam gerar um contato anormal entre essas estruturas ósseas, desencadear lesão condral e, como consequência, a artrose do quadril. Esse mecanismo foi denominado impacto fêmoro-acetabular. No entanto, a comprovação da relação entre o impacto e a artrose do quadril depende da uniformização dos critérios diagnósticos do cam e do pincer, ainda escassa e variável na literatura. Dessa forma, será possível a definição da prevalência e história natura do impacto fêmoro-acetabular e da sua relação com a artrose do quadril. Objetivo: Avaliar a prevalência do impacto fêmoro-acetabular tipo cam e tipo pincer em uma amostra de indivíduos assintomáticos. Pacientes e Métodos: Foram estudados 106 indivíduos assintomáticos (65 homens e 41 mulheres), com idade entre 20 e 40 anos. A condição determinante para a inclusão no estudo foi à ausência de história de dor no quadril ao longo da vida. Foram obtidas radiografias em ântero-posterior e Dünn 45°. A presença de cam foi determinada por um ângulo alfa, arbitrado, de 55° e a presença de pincer, quando observado o sinal da parede posterior e/ou o sinal de crossover. Resultados: Foi observada prevalência de cam de 29%; o sinal do crossover e da parede posterior ocorreram, respectivamente, em 20% e 29% dos indivíduos estudados. Pelo menos uma das imagens de impacto fêmoro-acetabular estava presente em 65% dos indivíduos da amostra. Conclusão: A prevalência encontrada das imagens de impacto fêmoro-acetabular (65%) está acima daquelas relatadas na literatura. É necessária a ampliação do estudo para confirmar os resultados encontrados e a realização de estudos prospectivos bem controlados para avaliar o papel do cam e do pincer no desenvolvimento da artrose do quadril. / Background: Anatomical abnormalities of the proximal femur or the acetabulum, such as those resulting from the consequences of slipped epiphyses of the proximal femur, the hip dysplasia of Legg-Calve-Perthes disease, could lead to the development of hip osteoarthrosis. Nevertheless, around 80% of individuals who develop this condition have a bone anatomy considered normal. Still, the hypothesis arose that subtle alterations of the proximal femur or the acetabulum, called, respectively, cam and pincer, could generate an abnormal contact between these bony structures, triggering chondral lesion and as a consequence, arthritis of the hip. This mechanism has been named femoroacetabular impingement. Nevertheless, evidence of the relationship between the impact and osteoarthritis of the hip depends on the standardization of diagnostic criteria of cam and pincer, still scarce and variable in the literature. Thus it will be possible to define the prevalence and natural history of femoroacetabular impingement and its relationship with hip osteoarthrosis. Aim: To determine the prevalence of cam-type and pincer-type femoroacetabular impingements in asymptomatic subjects. Patients and Methods: Were studied 106 asymptomatic subjects (65 males and 41 females) aged between 20 and 40 years. The determining condition for inclusion in the study was the absence of history of hip pain throughout life. Radiographs were obtained in anteroposterior pelvic view and Dunn 45° view. The presence of cam was determined by an angle alpha, arbitrated, 55 ° and the presence of pincer when the observed the posterior wall and / or crossover signs. Results: A prevalence of 29% of cam, and 20% and 29% of crossover sign and posterior wall sign respectively was found. At least, one of those radiographic signs of femoroacetabular impingement was found in 65% (68) of the cases. Conclusion: In conclusion, the prevalence of images of femoroacetabular impingement (65%) is above those reported in the literature. Increase of the study is necessary to verify the results found, and the performance of well-controlled prospective studies to evaluate the role of the cam and pincer in the development of osteoarthritis of the hip.

A utilização de implantes cirúrgicos para artroplastia de quadril com prótese de recapeamento da cabeça femoral como substituto ósseo é um procedimento que tem sido realizado em 35% dos casos de Osteoartrose nos EUA. Entretanto, o atrito da broca e o aumento da temperatura durante a usinagem da cabeça femoral são responsáveis pelo possível aquecimento do tecido ósseo, podendo provocar a necrose óssea térmica. Neste sentido, o desenvolvimento de novos ferramentais e metodologias para minimizar os danos térmicos do atrito torna-se importante. Diante disso, o presente estudo teve como objetivo verificar se há a ocorrência de necrose óssea em um procedimento de furação óssea utilizando o dispositivo EQUITRON; Mod.ES 2200, desenvolvido no LTC-EESC-USP. Para tal, utilizamos 4 amostras de costela bovina removidas após a morte do animal, que foram furadas com broca de aço inoxidável (HSS-SKF), de 8 milímetros, sem irrigação externa. As amostras foram furadas com rotações de 100, 1000, 1200 e 2500 RPM, aferidas por tacômetro foto/contato digital da marca MINIPA, MDT-2238, e com avanço controlado de 80 mm/min (dispositivo da marca-EQUITRON; MOD.ES 2200; RPM 2800; Potência 0,30; Torque 1,6 Nm). Foram mensuradas as temperaturas iniciais da broca e da amostra e a final da amostra com termômetro digital, marca-MEDISANA®. Após a furação foram confeccionadas lâminas histológicas (HE) do tecido ósseo, preparadas de acordo com a metodologia apropriada, para posterior qualificação e quantificação da ocorrência de necrose óssea térmica através de imagens captadas por microscopia óptica (Olympus BX 41TF - Made Japan) utilizando-se o programa Motic Images Plus 2.0 para a captura das imagens. Os valores de temperaturas aferidos na amostra após a furação apresentaram relação positiva com a RPM utilizada, isto é, quanto maior a rotação, maior foi a temperatura observada. Apenas a amostra furada a 2500 RPM ultrapassou a temperatura de referencia para a gênese da osteonecrose térmica, que é de 47ºC. As análises histológicas apresentaram uma baixa predominância de células picnóticas e lacunas, sugerindo menor dano tecidual. Os resultados obtidos no presente estudo sugerem que o dispositivo (furadeira) desenvolvido no LTC-EESC-USP para a realização das furações nas amostras ósseas em testes de bancada foi eficiente em minimizar a ocorrência de necrose óssea térmica, até mesmo em condições de temperatura acima do limite fisiológico aceitável. / The utilization of surgical implants for hip arthroplasty with a resurfacing prosthesis of the femoral head as a bone substitute have been conducted in 35% of osteoarthrosis cases in the USA. However, the friction of the drill and the increase in the temperature during the machining of the femoral head can possibly heat the bony tissue and provoke a thermal bone necrosis. The development of new tools and methodologies for minimizing the thermal damage of the friction has become fundamental. The present study analyzes the occurrence of bone necrosis in a procedure of bone drilling that uses an EQUITRON device, Mod. ES 2200, developed at the LTC-EESC-USP. Four samples of bovine ribs removed after the death of the animal were used for the tests. They were drilled by an 8mm stainless-steel drill (HSS-SKF) with no external irrigation, at 100, 1000, 1200 and 2500 RPM calibrated by a MINIPA, MDT-2238 digital photo/contact tachometer and whose 80mm/min. advance (EQUITORN device; MOD.ES 2200; RPM 2800; 0.30 Potency and 1,6Nm torque) was controlled. The initial temperatures of the drill and the sample and the final temperature of the sample were measured by a MEDISANA digital thermometer. After drilling, histological blades (HE) were produced from the bony tissue and prepared according to the adequate methodology for further qualification and quantification of the occurrence of thermal bone necrosis through images captured by optical microscopy (Olympus BX 41TF - made in Japan) and Motic Images Plus 2.0 program. The values of the temperatures measured in the sample after drilling showed a positive relation with the RPM utilized, i.e., the faster the rotation, the higher the temperature. Only the sample drilled at 2500RPM exceeded the reference temperature (47ºC) for the genesis of the thermal osteonecrosis. The histological analyses revealed a low predominance of picnotic cells and gaps, which suggest minor tissue damage. The results show the device (drilling machine) developed at the LTC-EESC-USP for the drilling in the bone samples in workbench tests is efficient to minimize the occurrence of thermal bone necrosis, even at temperatures above the physiological acceptable limit.