Orientador: Aparecido Carlos Gonçalves / Resumo: Os problemas associados às falhas protéticas e cirurgias de revisão aumentaram muito desde que a substituição total da articulação passou a ser aplicada também a pacientes mais jovens e mais ativos, portanto, a necessidade de resolver ou reduzir os problemas relacionados ao desgaste é de suma importância. Partindo-se dessa premissa, decidiu-se por projetar, fabricar e validar uma máquina de ensaio de desgaste do tipo acoplamento orbital, capaz de realizar o ensaio de desgaste de Prótese Total de Quadril (PTQ), obedecendo aos parâmetros de carga e movimento (Flexão/Extensão, Adução/Abdução), estabelecidos pela Norma ABNT NBR ISO 14242-3. Após a validação, foi realizado o ensaio de uma amostra composta de uma cabeça femoral de 28 mm de diâmetro de aço inox ASTM F138 e acetábulo de polietileno convencional (UHMWPE). O ensaio teve a duração de um milhão de ciclos (aproximadamente 12 dias), equivalente a aproximadamente um ano de uso da prótese in vivo e teve duas avaliações de perda de massa e volume ao longo do ensaio. Os resultados obtidos da taxa média de perda de massa e volume por milhão de ciclos, foram compatíveis com os resultados apresentados por outros autores. A avaliação do desgaste sofrido pelo componente acetabular (análise visual e microscópica) e a análise morfológica das partículas geradas pelo desgaste via MEV, forneceram informações importantes para melhor interpretar os mecanismos de desgastes (abrasão, adesão e fadiga) ocorridos durante o ensaio tribológico. ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The problems associated with prosthetic failure and revision surgery have increased greatly since total joint replacement has also been applied to younger and more active patients, so the need to resolve or reduce wear-related problems is of paramount importance. Based on this premise, it was decided to design, manufacture and validate a wear test machine of the orbital coupling type, capable of performing the Total Hip Prosthesis (PTQ) wear test, according to load and movement parameters ( Flexion / Extension, Adduction / Abduction), established by the Standard ABNT NBR ISO 14242-3. After validation, a sample composed of a 28 mm diameter femoral head of ASTM F138 stainless steel and conventional polyethylene acetabulum (UHMWPE) was performed. The assay lasted for one million cycles (approximately 12 days), equivalent to approximately one year of use of the prosthesis in vivo and had two mass and volume loss evaluations throughout the trial. The results obtained from the average loss rate of mass and volume per million cycles were compatible with the results presented by other authors. The evaluation of the wear of the acetabular component (visual and microscopic analysis) and the morphological analysis of the particles generated by the MEV wear, provided important information to better interpret the mechanisms of wear (abrasion, adhesion and fatigue) that occurred during the tribological test. It is a fact that these wear mechanisms compromise the useful life of a hip joint ... (Complete abstract click electronic access below) / Doutor

Submitted by Luis Guilherme de Faria null (lgfaria.medvet@ymail.com) on 2018-02-20T18:24:16Z No. of bitstreams: 1 TESE DE DOUTORADO - LUÍS GUILHERME DE FARIA - REPOSITÓRIO.pdf: 2930040 bytes, checksum: 40cde73090fb7af7b81a6b84ae05ed52 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-02-21T14:06:52Z (GMT) No. of bitstreams: 1 faria_lg_dr_jabo.pdf: 2930040 bytes, checksum: 40cde73090fb7af7b81a6b84ae05ed52 (MD5) / Made available in DSpace on 2018-02-21T14:06:52Z (GMT). No. of bitstreams: 1 faria_lg_dr_jabo.pdf: 2930040 bytes, checksum: 40cde73090fb7af7b81a6b84ae05ed52 (MD5) Previous issue date: 2018-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi comparar as propriedades biomecânicas de dois modelos de hastes femorais da prótese total de quadril, não cimentada, modular e nacional. A haste A, possui uma extensão na base do colo do implante, denominado “colar”, já o implante B, possui a sua porção proximal abaulada. Buscou-se determinar qual dos dois modelos de hastes femorais tem melhor desempenho ao evitar, ou impedir, o afundamento (subsidence). Para tal, utilizou-se 8 pares de fêmures de cães adultos, machos e fêmeas, de diferentes raças e massa corporal de ±25 kg. Em cada fêmur, uma ostectomia da cabeça e do colo femoral foi realizada e inserido um dos implantes selecionados. As construções foram submetidas, previamente, à radiografia e densitometria óssea, a fim de determinar a homogeneidade da amostra. Logo em seguida, divididos em dois grupos, Haste A (8 fêmures) e Haste B (8 fêmures), aplicou-se carga de flexo-compressão, no eixo axial de cada amostra, em máquina universal de ensaios. A força máxima, a deflexão, a resistência à compressão e a energia foram as variáveis analisadas nos dois sistemas, assim, o Grupo B exibiu valores significativamente maiores (p≤0,05) para as variáveis resultantes deste estudo, com exceção da rigidez que, estatisticamente, considerou-se similar entre os dois grupos (p=0,2031). A média da força máxima no teste de compressão axial para o Grupo A foi de 1347±357 N e, para o Grupo B, de 1805±123 N (p≤0,0069). A média da deflexão para o Grupo A foi de 5547±2639 mm e, para o Grupo B, de 10033±3998 mm (p≤0,0056). Para a variável energia, a média da força máxima para o Grupo A foi de 6203±3488 N.mm, já para o Grupo B, foi de 12885±5056 N.mm (p≤0,0054). A média do módulo de deformação elástica, expresso em rigidez, no Grupo A foi de 860±160 N/mm, já no Grupo B, de 1011±305 N/mm (p≤0,0054). Os dados obtidos apresentavam distribuição normal e foram submetidos ao teste t pareado (p≤0,05). Constatou-se que a Haste B possui maior força máxima, deflexão e energia. Todavia, quanto a rigidez, ambas são eficientes em amortizar o impacto das forças axiais de flexo-compressão em fêmures cadavéricos de cães. / The goal of this study was to compare the biomechanical properties of two models of femoral stems of the total hip, uncemented, modular, and national (Brazil) prosthesis. The stem A has an extension at the base of the implant, called the "collar", and the implant B, has its convex proximal portion. We sought to determine which of the two models of femoral rods perform best by avoiding, or preventing, subsidence. To this end, we used eight pairs of femurs of adult dogs, male and female, of different races and body weight ± 25 kg. In each femur, an ostectomy of the head and femoral neck was performed and inserted one of the selected implants. The constructs were previously submitted to radiography and bone densitometry, in order to determine the homogeneity of the sample. Then, divided into two groups, Stem A (8 femurs) and Stem B (8 femurs), a flexo-compression load was applied on the axial axis of each sample in a universal testing machine. Maximum strength, deflection, compressive strength and energy were the variables analyzed in both systems, thus, Group B showed significantly higher values (p≤0.05) for the variables resulting from this study, except for the rigidity that, statistically, it was considered similar between the two groups (p=0.2031). The mean maximal force in the axial compression test for Group A was 1347±357 N and, for Group B, 1805 ± 123 N (p≤0.0069). The mean deflection for Group A was 5547 ± 2639 mm and, for Group B, 10033±3998 mm (p≤0.0056). For the energy variable, the mean of the maximum force for Group A was 6203±3488 N.mm, for Group B, it was 12885±5056 N.mm (p≤0.0054). The mean elastic strain modulus, expressed as rigidity, in Group A was 860±160 N/mm, in Group B, of 1011±305 N/mm (p≤0.0054). The obtained data presented normal distribution and were submitted to paired t test (p≤0.05). It was verified that Haste B has greater maximum strength, deflection and energy. However, for stiffness, both are efficient in amortizing the impact of axial flexion-compression forces on cadaverous femurs of dogs.

Total hip arthroplasty (THA) is a highly successful surgical procedure, but complications remain, including aseptic loosening, early dislocation and misalignment. These may partly be related to lacking training opportunities for novices or those performing THA less frequently. A standardized training setting with realistic haptic feedback for THA does not exist to date. Virtual Reality (VR) may help establish THA training scenarios under standardized settings, morphology and material properties. This work summarizes the development and acquisition of mechanical properties on hip reaming, resulting in a tissue-based material model of the acetabulum for force feedback VR hip reaming simulators. With the given forces and torques occurring during the reaming, Cubic Hermite Spline interpolation seemed the most suitable approach to represent the nonlinear forcedisplacement behavior of the acetabular tissues over Cubic Splines. Further, Cubic Hermite Splines allowed for a rapid force feedback computation below the 1 ms hallmark. The Cubic Hermite Spline material model was implemented using a three-dimensional-sphere packing model. The resulting forces were delivered via a human–machine-interaction certified KUKA iiwa robotic arm used as a force feedback device. Consequently, this novel approach presents a concept to obtain mechanical data from high-force surgical interventions as baseline data for material models and biomechanical considerations; this will allow THA surgeons to train with a variety of machining hardness levels of acetabula for haptic VR acetabulum reaming.

Bakgrund: Ledrörelse- och belastningsrestriktioner är vanliga efter en total höftprotesoperation och syftar till att undvika att höftleden luxerar eller att suturerad muskulatur släpper under tiden som mjukdelarna läker, vanligen 6 – 8 veckor. Proteser och operationsteknikerna har förändrats med åren vilket lett till att antalet postoperativa luxationer minskat, och därav har vissa ortopedkliniker i Sverige börjat frångå postoperativa ledrörelse- och belastningsrestriktioner. Syfte: Att kartlägga vilka ledrörelse- och belastningsrestriktioner som rekommenderas efter en total höftprotesoperation på svenska ortopedkliniker samt om restriktionerna har förändrats under de senaste fem åren. Metod: Studien genomfördes som en kvantitativ tvärsnittsstudie med hjälp av en egenformulerad validerad webbenkät. Huvudresultat: Av de 16 svarande klinikerna uppgav 81 % att de hade någon form av restriktion (ledrörelse- eller belastningsrestriktion) för sina höftprotesopererade patienter. Vanligast var ledrörelserestriktioner där 62 % av respondenterna svarade ja på frågan ”rekommenderar din enhet/klinik patienter som opereras med höftprotesoperation några ledrörelserestriktioner”. Motsvarande siffra för belastningsrestriktioner var 50 %. En total avsaknad av restriktioner förekom hos 19 % av de svarande klinikerna. 63 % av klinikerna svarade att belastningsrestriktionerna hade förändrats för mer än 10 år sedan medan 50 % av klinikerna svarade att ledrörelserestriktionerna hade förändrats de senaste 5 åren. Resultatet i vår studie tydde på att användandet av postoperativa restriktioner har minskat. Den vanligaste förändringen var en minskning av användandet av postoperativa ledrörelserestriktioner, vilket hade skett hos 60 % av respondenterna. Konklusion: Vår studie visade att 4 av 5 svenska ortopedklinikerna som deltog i vår enkätstudie använde sig av ledrörelse- eller belastningsrestriktioner efter en höftprotesoperation och att 1 av 5 inte använde restriktioner. Hälften av klinikerna har förändrat ledrörelserestriktionerna de senaste fem åren, och färre än 40 % har förändrat belastningsrestriktionerna. / Background: Joint movement- and load precautions are common after a total hip arthroplasty and aims to prevent dislocation of the hip and to prevent the loss of sutured muscles while the soft tissue heal, usually 6-8 weeks. Prosthesis and surgical technics have changed over the years, which had led to a reduced number of postoperative hip dislocations and hence have some orthopedic clinics in Sweden begun abandon postoperative joint movementand load precautions. Aim: A mapping of the use of joint movement- and load precautions in Swedish orthopedic clinics and if there has been any changes in precautions during the last five years. Method: The study was conducted as a quantitative cross-sectional study with the help of a selfdeveloped validated online survey. Result: 81 % of the 16 respondent clinics stated they had some form of precautions (joint movement- or load precautions) for their hip replaced patients. The most common precaution was joint movement where 62% of respondents answered yes to the question "Does your unit/Clinic recommend patients undergoing surgery with total hip replacement any joint movement precautions". The corresponding figure for load precautions was 50%. A total absence of restrictions occurred in 19 % of the respondent clinics. 63 % responded that modifications of load precautions took place for more than 10 years ago while 50 % responded that the modifications of joint movement precaution took place over the past 5 years. The result in our study indicated that the use of precautions had decreased. The most common change was a decrease in jointmovementprecautions that occurred with 60 % of the respondents. Conclusion: In our study we found that 4 out of 5 Swedish orthopaedic clinics who participated in our survey recommended joint movement- or load precautions after a hip replacement and it also showed that 1 out of 5 didn´t recommend precautions. Half of the clinics had changed the movement precautions during the past five years, and less than 40 % had changed the load precautions.

<p>In this thesis, occurrence of heterotopic ossification (HO) following total hip arthroplasty (THA) was studied. Preventive effects and complications with non-steroidal anti-inflammatory drugs (NSAIDs) were analyzed. Experimental investigations on bone formation were employed to gain insight to the mechanism of NSAIDs action on bone.</p><p>(I). Fifty-six patients with bilateral THAs were analyzed. We found a strong correlation between HO on the two sides. Incidence and grade of HO were higher in men than in women.</p><p>(II). Sixty-nine patients with bilateral THAs who had been treated with NSAIDs after one or both THAs were analyzed for HO. Widespread HO occurred in untreated THAs, but in none of the treated THAs.</p><p>(III). A consecutive series of THAs were analyzed for HO. No widespread HO occurred in patients treated with NSAIDs for 21 days. In contrast, widespread HO occurred in 23% of patients not treated.</p><p>(IV). A randomized, double-blind, prospective study on 144 patients was performed to determine the efficacy and minimum treatment time with Ibuprofen for prophylaxis of HO after THA. Treatment with Ibuprofen was effective for preventing HO and a treatment time of 8 days was sufficient.</p><p>(V). A ten-year follow-up examination was performed on the patients from study IV. Thirteen patients had been revised. All but one belonged to groups treated with Ibuprofen. However, the prosthetic survival time was not statistically different for patients treated with NSAIDs compared to the control group. Eighty-four more patients underwent radiographic examination10 years after THA. Nine loose prostheses were found. These were equally distributed between NSAIDs-treated and non-treated THAs. When combining complications (revisions and radiographic loosening) no significant effects could be verified.</p><p>(VI). Experimental induction of heterotopic new bone with demineralized allogeneic bone matrix (DABM) and with bone autografts, was used in rats to study effects of NSAIDs on new bone formation. Indomethacin inhibited net bone formation in DABMs and in orthotopic fractured bone. In contrast, a net mineral loss occurred in autografts, but neither mineral content nor ⁴⁵Ca incorporation was affected by Indomethacin treatment. The amount of bone formed per mg implanted DABM was linearly correlated to implant size.</p>

In this thesis, occurrence of heterotopic ossification (HO) following total hip arthroplasty (THA) was studied. Preventive effects and complications with non-steroidal anti-inflammatory drugs (NSAIDs) were analyzed. Experimental investigations on bone formation were employed to gain insight to the mechanism of NSAIDs action on bone. (I). Fifty-six patients with bilateral THAs were analyzed. We found a strong correlation between HO on the two sides. Incidence and grade of HO were higher in men than in women. (II). Sixty-nine patients with bilateral THAs who had been treated with NSAIDs after one or both THAs were analyzed for HO. Widespread HO occurred in untreated THAs, but in none of the treated THAs. (III). A consecutive series of THAs were analyzed for HO. No widespread HO occurred in patients treated with NSAIDs for 21 days. In contrast, widespread HO occurred in 23% of patients not treated. (IV). A randomized, double-blind, prospective study on 144 patients was performed to determine the efficacy and minimum treatment time with Ibuprofen for prophylaxis of HO after THA. Treatment with Ibuprofen was effective for preventing HO and a treatment time of 8 days was sufficient. (V). A ten-year follow-up examination was performed on the patients from study IV. Thirteen patients had been revised. All but one belonged to groups treated with Ibuprofen. However, the prosthetic survival time was not statistically different for patients treated with NSAIDs compared to the control group. Eighty-four more patients underwent radiographic examination10 years after THA. Nine loose prostheses were found. These were equally distributed between NSAIDs-treated and non-treated THAs. When combining complications (revisions and radiographic loosening) no significant effects could be verified. (VI). Experimental induction of heterotopic new bone with demineralized allogeneic bone matrix (DABM) and with bone autografts, was used in rats to study effects of NSAIDs on new bone formation. Indomethacin inhibited net bone formation in DABMs and in orthotopic fractured bone. In contrast, a net mineral loss occurred in autografts, but neither mineral content nor 45Ca incorporation was affected by Indomethacin treatment. The amount of bone formed per mg implanted DABM was linearly correlated to implant size.

No description available.

The law of bone remodeling, commonly referred to as Wolff's Law, asserts that the internal trabecular bone adapts to external loadings, reorienting with the principal stress trajectories to maximize mechanical efficiency, thereby creating a naturally optimum structure. The primary objective of the research was to utilize an advanced structural optimization algorithm, called design space optimization (DSO), to create a numerical framework to perform a micro-level three-dimensional finite element bone remodeling simulation on the human proximal femur and analyze the results to determine the validity of Wolff's hypothesis. DSO optimizes the layout of material by iteratively distributing it into the areas of highest loading, while simultaneously changing the design domain to increase computational efficiency. The result is a "fully stressed" structure with minimized compliance and increased stiffness. The large-scale computational simulation utilized a 175µm mesh resolution and the routine daily loading activities of walking and stair climbing. The resulting anisotropic human trabecular architecture was compared to both Wolff's trajectory hypothesis and natural femur data from the literature using a variety of visualization techniques, including radiography and computed tomography (CT). The remodeling predictions qualitatively revealed several anisotropic trabecular regions comparable to the natural human femurs. Quantitatively, the various regional bone volume fractions from the computational results were consistent with CT analyses. The strain energy proceeded to become more uniform during optimization; implying increased mechanical efficiency was achieved. The realistic simulated trabecular geometry suggests that the DSO method can accurately predict three-dimensional bone adaptation due to mechanical loading and that the proximal femur is an optimum structure as Wolff hypothesized. The secondary objective was to revise this computational framework to perform the first in-silico hip replacement considering micro-level bone remodeling. Two different commercially available hip prostheses were quantitatively analyzed using stress, strain energy, and bone mineral density as performance criteria and qualitatively visualized using the techniques above. Several important factors for stable fixation, determined from clinical evaluations, were evident: high levels of proximal bone loss, distal bone growth, and medial densification. The results suggest the DSO method can be utilized for comparative prosthetic implant stem design, uniquely considering post-operation bone remodeling as a design criterion. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-08-16 15:30:55.144

Ce travail de thèse avait comme objectif l'amélioration des outils de planning préopératoire tridimensionnels (P3D) pour l'arthroplastie totale de la hanche. Lors de l'utilisation d'implants sans ciment, une bonne stabilité primaire est requise pour obtenir une ostéointégration satisfaisante. Pour cela, une sélection appropriée de la taille et de la position de la prothèse est indispensable. En utilisant des images scanner obtenues par tomographie à rayon X de la hanche des patients, le chirurgien peut se servir du P3D pour faire la sélection de l'implant et anticiper sa position finale. Aujourd'hui, les méthodes de planning disponibles ne fournissent pas de critère mécanique qui pourrait refléter la qualité du contact os-implant. Nous proposons une méthode pour l'amélioration du P3D basé sur une analyse vibratoire par éléments finis pour le calcul de paramètres mécaniques personnalisés et liés á la stabilité primaire. Nos résultats suggèrent que la réponse modale de la tige est très sensible aux changements de l'aire de contact et de la raideur apparente de l'interface os-implant. Une transition marquée du comportement modal associée à un ancrage plus ou moins bon a permis de définir des seuils qui pourraient potentiellement discriminer des implants stables et instables dans le cadre du planning. Nous avons aussi étudié l'effet de la procédure de râpage et son possible impact sur le P3D. L'effet de la râpe sur la microstructure de l'os à l'interface os-implant a été analysé ex-vivo à l'aide d'images de micro-scanographie. Une distribution spatiale de la raideur de l'os en contact avec l’implant a aussi été obtenue par indentation des mêmes pièces anatomiques. / This thesis work is concerned with the enhancement of three-dimensional preoperative planning (P3D) tools for total hip reconstruction. When cementless implants are used, primary stability is vital for a good osseointegration. For this, a correct selection of the size and position of the implant is necessary. The surgeon may use P3D based on the computed tomography scanner of the patient’s hip to optimally select the implant’s size and anticipate the final implant’s position. Available planning methods lack a mechanical criterion reflecting the actual quality of the bone-implant contact. In this work we propose a method to improve P3D using a vibrational finite element analysis to calculate patient-specific mechanical parameters representative of primary stability. We found that the modal response of the stem is very sensitive to changes of the area and apparent stiffness of the bone-implant interface. A clear transition between loose and tight contact allowed the definition of thresholds that could potentially discriminate between a stable and an unstable stem. We also studied the effect of the broaching procedure and its relevance for P3D. The effect of broaching on bone microstructure at the bone-implant interface was analyzed using cadaveric samples and micro-computed tomography. A mapping of the stiffness of bone in contact with the implant was obtained with indentation on the same cadaveric samples.

Aseptic loosening of the components is probably the most common long-term complication resulting in failure of Total Hip Arthroplasty. The mechanical behaviour of bone under load is one of the contributory causes of loosening encountered at the prosthesis/cement/bone interface. The present study dealt with a series of invitro experiments conducted on epoxy resin models of human hemi-pelves with different commercially available acetabular components implanted in them. These are used for the construction of simplified models of the artificial hip joint (three-dimensional) and of the prosthesis/cement/bone acetabular interface (two-dimensional). Loading conditions for the models included tensioning of the simulated abductor muscles for the hemi-pelvic and femoral loading for the prosthesis/cement/bone interface study. The experimental method employed was real-time holographic interferometry, a stress analysis technique recently used in the biomechanical field, which permitted whole-field simultaneously inspection of deformation patterns. The holographic interferograms were interpreted in a qualitative rather than a quantitative manner. The models do not exactly represent the in-vivo situation. Since this study identified high stresses both in the hip bone as well as in the interface (prosthesis/bone) it is suggested that these stresses are implicated in the mechanical pathogenesis of loosening. The observed changes in stress levels detected in our models could serve as a guide for future designs of acetabular prostheses as well as guide a in surgical techniques.