Total hip arthroplasty commonly involves a hard metallic/ceramic femoral ball component articulating against an acetabular ultra-high molecular weight polyethylene (UHMWPE) counter-bearing. A novel six-station, wear tribometer, featuring programmable load and motion, was designed to further the investigation into wear, sub-surface plasticity and debris generation of UHMWPE. This thesis describes the pin-on-plate device, its validation and subsequent use to assess unirradiated (-PE) and gamma-irradiated highly crosslinked (+PE) UHMWPE wear behaviour. With the emphasis on dynamic loading and a closer gait matched open wear path, the tribometer improves on the clinical relevance of pin-on-plate testing. There is a requirement for this type of machine in order to investigate the directional dependence of wear and debris generation of UHMWPE more accurately, where “simplified” tribometers (adequate for constant load/constant velocity and constant load/sinusoidal velocity work) are not capable or suitable. For the first time in orthopaedic pin-on-plate studies, tests were conducted using an advanced dynamic load synchronised to a more physiologically accurate elliptical motion path. To validate the machine, three orthopaedic polymers of clinical relevance; Polytetrafluroethylene, Polyacetal, and UHMWPE were subjected to linear-reciprocating (LR) and novel elliptical motion paths under a Paul-type load profile. All three polymers showed higher wear factors under elliptical motion, by up to 2 orders of magnitude, agreeing well with explanted values. The UHMWPE elliptical wear factor was comparable to that reported for clinical, where kelliptical = 1.56 x 10-6 mm3/Nm. In the crosslinked study, the mean steady state wear of -PE and +PE groups under linear reciprocating motion was not significantly different. However, under elliptical motion, crosslinking reduced UHMWPE wear by up to 92% when compared to the unirradiated group. In –PE pins worn under LR motion and in +PE pins subjected to both motion paths a sub-surface damage zone with reduced crystallinity and increased strain was measured using Raman spectroscopy. This was attributed to large strain accumulation in the slower wearing surfaces providing a mechanism for de-crystallisation. The discovery of such a near-surface layer is in good agreement with critical strain wear models. In disagreement, however, we found the sliding induced layer to extend to greater depths than previous reported.

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.

Die Möglichkeiten der operativen Rekonstruktion degenerativ veränderter Hüftgelenke sind komplex und vielfältig. Bei den derzeit zur Verfügung stehenden operativen Behandlungsmassnahmen führen die Vor- und Nachteile immer wieder zur Diskussionen und Abwägung der Operationsverfahren. Hierbei stehen sich die rasche postoperative Mobilisierung sowie eine verminderte Rekonvaleszenzzeit mit den diskutierten Nachteilen einer schlechteren Übersichtlichkeit und damit verbundenen Fehlimplantationen gegenüber. Dies und die damit verbundene volkswirtschaftliche Bedeutung sind ein ständiger Ausgangspunkt für das Bemühen den optimalen Zugangsweg zu etablieren. Daher stellte das von Smith-Peterson 1949 publizierte Verfahren einen Meilenstein in der operativen Therapie dar. Hierdurch konnten zum einen die operationstechnischen Vorteile wie auch das volkswirtschaftliche Begehren nach kürzeren postoperativen Verweildauern vereint werden. Die Modifizierung dieses Zugangsweges hat sich bereits in einer großen Anzahl prospektiver Studien als zuverlässiges Rekonstruktionsverfahren etabliert und erfüllt zudem auch die Anforderungen der heutigen Medizin nach ästhetisch schönen Ergebnissen. In der vorliegenden Arbeit wurde eine prospektive Fallstudie des direkten anterioren Zugangs mit einem gesunden Vergleichskollektiv durchgeführt. Mit dem Ziel, die Aktivität ein Jahr postoperativ nach Implantation einer HTEP mit gesunden Probanden zu vergleichen. Von Januar 2009 bis Mai 2011 wurden insgesamt 77 Patienten und 59 Probanden in die Studie aufgenommen. Als Vergleichswerte wurde zum einen die klinische wie auch die radiologische Untersuchung herangezogen. In der klinischen Untersuchung zeigte sich insgesamt ein signifikanter Anstieg der untersuchten Scores im Vergleich mit den präoperativen Ergebnissen bei den Operierten. Im Vergleich zu den Probanden erzielen die Patienten ein Jahr nach HTEP teilweise noch schlechtere Werte in dem Bewegungsumfang und den Aktivitätsniveaus welche mittels der Auswertung des Stepwatches, des TWB und des Arzt-Patienten-Fragebogens erhoben wurden. Die radiologische Bewertung diente zur Feststellung der Positionierung der HTEP. Mit guten Positionierungen durch den direkten anterioren Zugang. Die Bewertung der Funktionalität zwischen den beiden Gruppen erfolgte durch den HHS, XSFMA- D und den Arzt-Patientenfragenbogen. Hierbei konnten ähnliche Ergebnisse, wie bereits oben beschrieben, verzeichnet werden mit guten Werten in der Gruppe der untersuchten Patienten, jedoch einer geringeren Funktionalität im Vergleich zu den Probanden. Die vorliegende Arbeit zeigt, dass der direkte anteriore Zugang die Wiederherstellung eines guten postoperativen Gesundheitszustandes mit erreichen eines hohen postoperativen Aktivitätslevels der Patienten ermöglicht. Ebenso erfüllt dieser Zugangsweg die Anforderungen der heutigen Medizin im Sinne einer schnellen postoperativen Mobilisation. Im Vergleich zu anderen minimal-invasiven Verfahren zeigen sich eine gute Implantierbarkeit, eine gute Positionierung und ein niedriges Komplikationsniveau. Prinzipiell hat der minimal-invasive anteriore Zugang das Potenzial sich als ein Standardverfahren in der operativen Rekonstruktion bei Hüftgelenksersatz zu etablieren, jedoch wäre ein direkter Vergleich mit dem lateralen Zugang erstrebenswert und sollte in weiteren Studien verglichen werden. / Background: The aim of this prospectve study was to evaluate the clinical results one year after total hip arthroplasty performed through a minimally invasive direct anterior approach versus a healthy volunteer group. Methods: 77 patients and 59 probands have been evaltuated applying the Stepwatch activity monitor (SAM), the Harris hip score (HHS), the SF 36, a daliy activity questionnaire (DAQ) and the XSFMA. Results: The average SAM showed significant differences of 5658 steps (patients) compared to 6417 steps (proband) (p=0,011). The same routcome can be seen in the DAQ with 4226 (patients) and 4686 (proband) cycles (p=0,327) respectively. No significant difference occured by using the average HHS reflecting an equal outcome of 90,7 points in the patient group compared to 90.8 points in the proband group (p=0,022). In contrast tot he afore-mentioned HHS, was a significant increase of the XSFMA reported with 10,9 (patients) and 5.0 (proband) (p=0,001). The SF -36 physical component scores were 45.8 (patients) and 50.6 (proband) while the psychometric properties added up to 56.6 (patients) and 55.9 (proband). While the physical component scores (p=0,001) showed a significant difference this couldnt be observed for the psychometric properties (p=0,511). Conclusion: In our study, good results have been obtained after the first year of the total hip arthroplasty, however these are not as beneficial as the outcomes in the healthy volunteer group.

The aim of this thesis was to determine if the size of the femoral head can influ-ence corrosion at the head-neck taper interface of total hip arthroplasty (THA) prosthe-ses. A hypothesis was developed that large head sizes could result in a greater toggling torque at the head-neck taper interface by increasing the distance between the centre of the femoral head to the centre of the neck taper. This could result in increased micromotion and deteriorate the passive oxide film along the head-neck taper interface; thus, making the taper interface vulnerable to corrosion. A retrieval analysis of 74 THA prostheses studied the corrosion damage at the head-neck taper interface. This study revealed that prostheses featuring 36 mm femoral heads had significantly greater head taper corrosion than prostheses with a 28 mm head. Finite element analysis was performed afterwards to identify if the use of large femoral heads can increase the micromotion at the head-neck taper interface due to a greater toggling torque. This experiment demonstrated that with a larger head size the micromotion at the head-neck taper interface increases. An in vitro corrosion fatigue study was performed afterwards following ASTM F1875-98. When applying an off-axis fatigue load, prostheses featuring a 36 mm femoral head displayed significantly more corrosion damage at the head-neck taper interface than those with a 28 mm femoral head. Axial fatigue loading was also applied; negligible corrosion damage at the head-neck taper interface was discovered in comparison to the prostheses that received an out of axis load. This verifies that the use of large femoral heads can result in increased head-neck taper corrosion due to a greater toggling torque.

No description available.

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.

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.

Surgical interventions on the hip joint have greatly increased over the past decade, with the cumulative cost total hip arthroplasties (THA) alone exceeding $400B/year by 2020. Although positive patient-reported outcomes and satisfaction after THA and hip preservation for cam femoroacetabular impingement (FAI) are among the highest in orthopaedics, a limited number of research has investigated the biomechanics of dynamic activities following-up the surgery. This doctoral thesis examined the kinematics, muscle force component, and hip contact loading in pre- and postoperative patients during the deep squat motion. Specifically, this research: 1) examined muscle strength and pelvic kinematics in asymptomatic FAI, 2) examined lower-limb kinematics and muscle activity in postoperative patients who underwent either THA or FAI correction during a deep squat task, and 3) examined muscle force contributions and hip contact forces (HCF) during dynamic motion in postoperative FAI patients. First, clinical and medical imaging evaluations classified the participants into three groups: symptomatic FAI, asymptomatic FAI (FAD – participants had the cam deformity, but no pain), and healthy controls. The FAD participants had significantly greater hip extensor strength compared to the FAI and CTRL groups, which allowed them to achieve greater pelvic mobility and squat as deep as the CTRL group. Second, at the follow-up for the FAI surgery the patients showed increased pelvic ROM during the squat, and weakness associated with hip flexion and hip flexion-with-abduction were associated with postoperative alterations. For the THA follow-up analyses, the patients using a dual- mobility (DM) prosthesis reached an anterior pelvic tilt similarly to the CTRL during the dynamic parts of the squat; however, without returning its neutral tilt at the bottom of the squat, while the single- bearing (SB) prosthesis was associated with excessive hip abduction during the squat. Third, a generic full-body musculoskeletal model (MSKM) was optimized to allow for the analysis of tasks with a high range of motion (ROM; e.g. deep squat task), which controlled muscle moment arms during the high joint flexions to avoid the model’s motor tendon units (MTU) to penetrate the bony structures and respect the anatomical via points. Simulation performed during gait demonstrated that FAI patients enhance medial-lateral hip stability postoperatively, allowing reduced dynamic forces of the muscles associated with the sagittal aspect of the gait due to a less compensatory strategy to stabilize the hip joint. Furthermore, simulations performed during deep squat showed a higher anterior pelvic tilt in postoperative FAI patients as a ‘restore to native’ mechanism once the cam-deformity was no longer present. Increased semimembranosus force was linked to higher vertical HCF and total magnitude. The outcomes of this research include findings for gait and squat analyses that provide a better understanding of the pelvic mobility and hip muscle forces in hip diseases. In silico models can improve biomechanical assessment of postoperative patients in order to quantify surgical effectiveness and support clinicians in making subject-specific case decisions. The contributions also lay on the assertion of helping us to formulate future research directions in biomechanics applied to the orthopaedics field.