Use of cone beam computed tomography, a desktop 3D printer and freeware for manufacturing craniofacial bone prostheses: a pilot study / Utilización de la tomografía cone-beam para la confección de protesis óseas craniofaciales por impresora 3D de escritorio usando programas libres: un estudio piloto

The aim of this study was to reconstruct missing bone parts using cone beam computed tomography (CBCT), freeware and a desktop 3D printer. Materials and Methods: A human skull was used and osteotomies were performed in the frontal process of the zygomatic bone, zygomatic process of the temporal bone and part of the parietal bone. The 3D image was then obtained CBCT and the DICOM file was transformed into STL and exported using InVesalius software. Missing bone parts were modeled by overlapping with OrtogOnBlender software for later printing using a desktop 3D printer. Result: The obtained prostheses had very good adaptation to the missing bone parts. Conclusion: It is feasible to make bone prostheses by 3D printing using low-cost desktop printers, as well as the use of free open-source software programs through CBCT.

El objetivo de este estudio fue el de reconstruir partes óseas faltantes usando tomografía computarizada de haz cónico, programas de licencia libre e impresora 3D de escritorio. Materiales and Métodos:Se utilizó un cráneo humano y se le realizó osteotomías en la apófisis frontal del hueso cigomático, apófisis cigomática del temporal y parte del parietal. Seguidamente se obtuvo la imagen en 3D por medio de la tomografía cone-beam y se exportó el formato DICOM para STL usando el programa libre InVesalius. Se modelaron las partes óseas faltantes por superposición con el programa libre OrtogOnBlender para su posterior impresión utilizando una impresora 3D de escritorio. Resultados: Las prótesis obtenidas tuvieron muy buena adaptación en las partes óseas faltantes. Conclusión:Es factible confeccionar prótesis óseas por impresión 3D utilizando impresoras de escritorio de bajo costo, así como la utilización de programas libres de código abierto a través de la tomografía cone-beam.

Diseño de exoesqueletos para miembro inferior / Exoskeleton design for lower limb

Introducción: La desarticulación de cadera es realizada por cirujanos para prevenir el crecimiento de enfermedades malignas en casos que no pueden ser tratados en forma conservadora. Existe la posibilidad que la desarticulación pueda ser causada por un accidente traumático que comprometa uno o los dos miembros inferiores. Objetivo: modificar el diseño de una prótesis para personas con problemas de tensión muscular, para cargas pesadas y movimientos repetitivos, para ser usada en personas con desarticulación unilateral o bilateral de cadera, partiendo de la patente de invención. Métodos: El diseño se realizó teniendo en cuenta desplazamiento similar al sistema locomotor humano, el confort, las posibles lesiones en las prominencias óseas, la repetitividad y el bajo costo. Para garantizar el menor impacto en la prominencia ósea disminuyendo el riesgo de ruptura o ulceras se usó un escáner 3D con sensores de presión para una correcta distribución de la presión sobre toda la prominencia de la cadera. Resultados: El sistema propuesto resultó en una alternativa para personas con limitaciones de movilidad en miembro inferior permitiendo un movimiento más natural y así mejorar la calidad de vida de este tipo de pacientes. La técnica permitió al usuario un alto nivel de independencia en situaciones de pérdida de los miembros inferiores. Conclusiones: El estudio se centró en la modificación de una prótesis para miembro inferior usado para personas con baja tonicidad muscular o actividades repetitivas a un sistema para personas con desarticulación bilateral de cadera o pérdida de un solo miembro inferior(AU)

Introduction: Hip disarticulation is performed by surgeons to prevent the growth of malignant diseases in cases that can not be treated conservatively. There is a possibility that the disarticulation may be caused by a traumatic accident involving one or both lower limbs. Objective: to modify the design of a prosthesis for people with muscular tension problems, for heavy loads and repetitive movements, to be used in people with unilateral or bilateral hip disarticulation, starting from the patent of invention. Methods: The design was made taking into account displacement similar to the human locomotor system, comfort, possible lesions in bony prominences, repetitiveness and low cost. To guarantee the least impact on the bone prominence, reducing the risk of rupture or ulcers, a 3D scanner with pressure sensors was used to correctly distribute the pressure over the whole hip prominence. Results: The proposed system resulted in an alternative for people with mobility limitations in the lower limb allowing a more natural movement and thus improving the quality of life of this type of patients. The technique allowed the user a high level of independence in situations of loss of the lower limbs. Conclusions: The study focused on the modification of a lower limb prosthesis used for people with low muscle tone or repetitive activities to a system for people with bilateral hip disarticulation or loss of a single lower limb(AU)

Experimental implantation of an arterial substitute made of silicone reinforced with polyester fabric in rabbits

OBJECTIVES: The aim of this study was to analyze silicone tubes with an internal diameter of 4 mm as a possible material for vascular prostheses. METHODS: Grafts were implanted into the infrarenal aortas of 33 rabbits. Fluoroscopic examinations were performed within 150 days after surgical implantation. Sample grafts were analyzed via electron microscopy to evaluate the eventual endothelialization of the prostheses. RESULTS: The patency rates of the prostheses were 87% (±6.7%) after 30 days, 73% (±9.3%) after 60 days and 48% (±12%) after 120 days. The material presented characteristics that support surgical implantation: good tolerance promoted by polyester tear reinforcement, ease of postoperative removal and a lack of pseudoaneurysms. However, intimal hyperplasia was a limiting factor for the patency rate. CONCLUSIONS: We concluded that polydimethylsiloxane has limited potential as an alternative material for small vascular prostheses.

Structural and mechanical characterization of custom design cranial implant created using additive manufacturing

Background: Reconstruction of customized cranial implants with a mesh structure using computer-assisted design and additive manufacturing improves the implant design, surgical planning, defect evaluation, implant-tissue interaction and surgeon's accuracy. The objective of this study is to design, develop and fabricate cranial implant with mechanical properties closer to that of bone and drastically decreases the implant failure and to improve the esthetic outcome in cranial surgery with precision fitting for a better quality of life. A customized cranial mesh implant is designed digitally, based on the Digital Imaging and Communication in Medicine files and fabricated using state of the Art-Electron Beam Melting an Additive Manufacturing technology. The EBM produced titanium implant was evaluated based on their mechanical strength and structural characterization. Results: The result shows, the produced mesh implants have a high permeability of bone ingrowth with its reduced weight and modulus of elasticity closer to that the natural bone thus reducing the stress shielding effect. Scanning electron microscope and micro-computed tomography (CT) scanning confirms, that the produced cranial implant has a highly regular pattern of the porous structure with interconnected channels without any internal defect and voids. Conclusions: The study reveals that the use of mesh implants in cranial reconstruction satisfies the need of lighter implants with an adequate mechanical strength, thus restoring better functionality and esthetic outcomes for the patients.

Prótese óculopalpebral com captação de movimento palpebral: proposta de dispositivo mecânico / Oculopalpebral prosthesis with eyelid motion capture: mechanical appliance proposition

Introdução: A reconstrução de grandes defeitos da face nem sempre é passível de correção cirúrgica, podendo ser restaurados com as próteses faciais. Apesar da prótese óculopalpebral apresentar uma aparência natural, ela é facilmente notada, pois não apresenta os movimentos palpebrais de abertura e fechamento sincronizadas com o olho contralateral, tornando assim a reconstrução protética um grande desafio. Objetivos: Planejar, desenhar, viabilizar e construir um protótipo com recurso mecânico/elétrico possibilitando sincronia dos movimentos palpebrais com o olho sadio para utilização em prótese óculopalpebral. Material e Métodos: Confecção de uma prótese óculopalpebral com um dispositivo de pálpebra móvel em silicone médico capaz de conectar-se a um sistema mecânico-elétrico responsável por realizar movimentos de abertura e fechamento da pálpebra móvel da prótese. Resultados e Discussão: Foi confeccionada uma prótese óculo-palpebral em resina acrílica termicamente ativada, criando-se um nicho para a acomodação de um sistema elétrico e possibilitar a livre movimentação de uma fina pálpebra em silicone interligada ao dispositivo tornando possível a conexão desse sistema com um sensor que capta o movimento palpebral de um olho saudável. Conclusão: No presente estudo um protótipo mecânico - elétrico foi planejado, desenhado e desenvolvido acoplado a uma prótese óculopalpebral estabelecendo e sincronizando seus movimentos palpebrais com o olho sadio.

Introduction: Surgical reconstruction of large facial defects may not be always possible. Extraoral maxillofacial prosthesis are a good restorative option. Even though when the oculopalpebral prosthesis presents a natural appearance, it can be easily noticed because its eyelids do not move. It is desirable for the eyelids to open and close synchronously with contralateral eye. Thus, prosthetic reconstruction of oculopalpebral region is a great challenge. Objectives: To plan, design, enable and build a oculopalpebral prosthesis prototype with mechanical and electric features allowing eyelid motion with synchronization with the sound eye. Material and method: Fabrication of an oculopalpebral prosthesis with a medical grade silicone movable eyelid which has the capability to connect itself to an mechanical-eletrical system responsible to make opening and closing movements on prosthesis movable eyelid. Results and discussion: An oculopalpebral prosthesis was made in thermoactivated acrylic resin. A gap was created to accomodate an electrical system and also allow free motion of a thin silicone eyelid attached to the dispositive. This system can be connected to a sensor which captured the eyelid motion of a sound eye. Conclusion: A mechanical-electrical prototype was planned, designed and developed attached to an oculopalpebral prosthesis stablishing and synchronizing its eyelid movements with the sound eye.

Three Dimensional Morphometry of Distal Femur to Design Knee Prosthesis for Indonesian Population / Morfometría Tridimensional del Fémur Distal para Diseñar Prótesis de Rodilla para la Población Indonesia

The objective of this study was to design custom-made prosthesis in a certain population, the morphometry needs to be measured. The results of this study were expected to provide basic data to design the ideal size of the total knee arthoplasty prosthesis for Indonesian population. This was an anthropometric study conducted on 100 healthy Indonesian population based on Computer Tomographic (CT) imaging on the distal femur resected surface. The parameters being used were Femoral Medio Lateral (fML) length, Femoral Antero Posterior (fAP) length, Femoral Medial Antero Posterior (fMAP) length, Femoral Lateral Antero Posterior (fLAP) length, and Femoral Aspect Ratio (FR). We found that the mean fAP and fML were 54.60±5.71 and 65.98±6.51, respectively. The morphometry of the distal femur were significantly different between male and female (male have larger build), however one of parameters showed different result: fLAP. This study showed that Indonesian people have smaller build compared with their Western counterpart. The proposed dimensions can be used as the basic data to design the ideal size of the custom-made knee arthoplasty prosthesis for Indonesian population.

El objetivo fue diseñar una prótesis a medida para una determinada población, por tanto la morfometría debía ser medida para proporcionar datos básicos para diseñar el tamaño ideal de una prótesis total para la artroplastia de rodilla en población de Indonesia. Se realizó un estudio antropométrico sobre 100 sujetos sanos indonesios, basados en tomografías computadorizadas (TC) de la superficie resecada del fémur distal. Los parámetros que se midieron fueron longitud femoral mediolateral (FML), longitud femoral anteroposterior (FAP), longitud femoral medial anteroposterior (FMAP), longitud femoral lateral anteroposterior (FLAP), y razón de aspecto femoral (FR). Las medias FAP y FML fueron 54,60±5,71 y 65,98±6,51, respectivamente. La morfometría del fémur distal fue significativamente diferente entre hombres y mujeres (mayor tamaño en hombres), sin embargo uno de los parámetros mostró resultados diferentes, la FLAP. Las personas indonesias son de menor tamaño en comparación con su contraparte occidental. Las dimensiones propuestas se pueden utilizar como los datos básicos para diseñar el tamaño ideal para una prótesis de rodilla a medida para la población de Indonesia.

Stent aórtico pulsátil: uma nova alternativa na assistência ventricular crônica / Pulsatile stent graft: a new alternative in chronic ventricular assistance

OBJETIVO: A insuficiência cardíaca é uma das causas mais comuns de internação. Dispositivos para assistência circulatória crônica foram testados e, em sua maioria, são de alta complexidade. O objetivo deste estudo é a descrição de uma endoprótese contrátil com capacidade de pulsação crônica no interior da aorta descendente, de maneira semelhante à produzida pelo balão intra-aórtico. MÉTODOS: Endopróteses pulsáteis compostas de níquel-titânio foram posicionadas de forma a envolver tubos de látex, simulando a aorta. Diferentes correntes elétricas foram aplicadas a unidades ligadas em série, de modo a causar contração da estrutura e deslocamento de uma coluna líquida. Foram realizadas duas sequências de testes: a primeira com duas gaiolas metálicas e a segunda com cinco gaiolas. Na primeira sequência de testes, aplicou-se tensão de 16,3 volts e corrente de 5 amperes e, na segunda sequência, tensão de 15 volts e corrente de 7 amperes. RESULTADOS: Na primeira sequência de testes, obteve-se o efeito pulsátil dos 2 stents, havendo contração do tubo e deslocamento da coluna d'água suficientes para validar o efeito pulsátil da endoprótese. As duas estruturas ejetaram um volume de 2,6 mL por ciclo, com uma variação de 29 mm na altura da coluna de água, equivalente a 8% de contração durante a pulsação. Na segunda sequência, conseguiu-se uma variação de 7,4 mL por ciclo. CONCLUSÃO: Os resultados obtidos comprovam a contratilidade da endoprótese pulsátil ativada pela aplicação de corrente elétrica. Continuidade do estudo e aperfeiçoamento do material se fazem necessários para obtenção de modelo mais eficiente do ponto de vista energético e com maior pulsação, para permitir volumes de ejeção comparáveis aos de balões intra-aórticos.

OBJECTIVE: Heart failure is currently one of the most common hospitalization causes. Several chronic circulatory assist devices have been tested and are highly complex. The objective is the description of a pulsatile endoprosthesis capable of applying a chronic pulse within the descending aorta, similar to that produced by intra-aortic balloon. METHODS: Pulsatile stents composed of nickel-titanium were built and positioned to engage latex tubes simulating the aorta. Different electric currents were applied to units connected in series in order to cause structure contraction and displacement of a liquid column. There were two sequence tests: first composed of two metallic cages and the second composed of five cages. At first sequence tests was applied a voltage of 16.3 volts and a current of 5 amperes. In the second, voltage of 15 volts and current of 07 amperes. RESULTS: In the first sequence was obtained the pulsatile effect of stent, with contraction of the tube and displacement of the water column sufficient to validate the pulsating effect of the endoprosthesis. The two structures ejected a volume of 2.6 ml per cycle, with a range of 29 mm in height of the column of water equivalent to 8% shrinkage during the pulse. In the second sequence, it reachead a variation of 7.4 mL per cycle. CONCLUSION: The results obtained confirm the stent pulsatile contractility activated by electrical current. The continuity of the study and material improvement are necessary to obtain more efficient model from the point of view of energy and pulse, to allow ejection volumes comparable with the intra-aortic balloons.

Nasalance and nasality at experimental velopharyngeal openings in palatal prosthesis: a case study

The use of prosthetic devices for correction of velopharyngeal insufficiency (VPI) is an alternative treatment for patients with conditions that preclude surgery and for those individuals with a hypofunctional velopharynx (HV) with a poor prognosis for the surgical repair of VPI. Understanding the role and measuring the outcome of prosthetic treatment of velopharyngeal dysfunction requires the use of tools that allow for documenting pre- and post-treatment outcomes. Experimental openings in speech bulbs have been used for simulating VPI in studies documenting changes in aerodynamic, acoustic and kinematics aspects of speech associated with the use of palatal prosthetic devices. The use of nasometry to document changes in speech associated with experimental openings in speech bulbs, however, has not been described in the literature. Objective: This single-subject study investigated nasalance and nasality at the presence of experimental openings drilled through the speech bulb of a patient with HV. Material and Methods: Nasometric recordings of the word "pato" were obtained under 4 velopharyngeal conditions: no-opening (control condition), no speech bulb, speech bulb with a 20 mm² opening, and speech bulb with 30 mm² opening. Five speech-language pathologists performed auditory-perceptual ratings while the subject read an oral passage under all conditions. Results: Kruskal-Wallis test showed significant difference among conditions (p=0.0002), with Scheffé post hoc test indicating difference from the no-opening condition. Conclusion: The changes in nasalance observed after drilling holes of known sizes in a speech bulb suggest that nasometry reflect changes in transfer of sound energy related to different sizes of velopharyngeal opening.

Diseño personalizado de una interfaz mioeléctrica para una prótesis de miembro superior / Custom design of a myoelectric interface for upper limb prostheses

Desde los años sesenta se utilizan las señales electromoigráficas (EMG) como señales de control para prótesis actuadas por servomotores, así como en la estimulación de músculos que sufren de parálisis o de atrofia parcial. Mediante el avance tecnológico se ha logrado mejorar el diseño, así como la fabricación de sistemas protésicos, que funcionan como extensiones de algún miembro del cuerpo humano, agregando además con los nuevos diseños, características básicas como: flexibilidad, estética morfológica, incremento de la relación resistencia/peso así como multifuncionalidad. Una prótesis mioeléctrica es una estructura desarrollada con el fin de reemplazar una parte o la totalidad de un miembro del cuerpo humano, lo mismo que suplir las funciones perdidas de este, sin dejar de lado la imagen corporal del paciente. Estas prótesis son accionadas por actuadores que se controlan a través de señales EMG, las cuales se obtiene mediante agujas intramusculares superficiales o por medio de electrodos colocados en el muñón del paciente. Este tipo de prótesis es cada vez más aceptado por personas con amputación de mano, ya que proporciona un mejor desempeño y permite el incremento de funcionalidad para el paciente que la utiliza, debido a que su control es más sencillo.

Since 60’s electromiographical signals (EMG’s) are used like a control signals for prostheses acted by servomotors, as well as stimulation of muscles that are affected due to partial or total paralysis. By means of technological advance, it has been possible to improve the design as well as the production of prosthetic systems that work as extensions of some member of human body, adding with the new designs also basic characteristics as: flexibility, aesthetic morphology, and superior strength/weight relationship, as well as multi-functionality. Mioelectric prosthesis is a structure developed with the purpose of replacing a part or the entirety member of human body, same as to replace the lost functions of this, without leaving aside patient's corporal image. These prostheses are acted by actuators that are controlled through EMG signals, which are obtained by means of intramuscular or superficial needles, or by means of electrodes placed in patient's stump. This class of prostheses is more and more accepted by people with hand amputation since it provides a better acting, that which allows a superior functionality for patient that uses it, because its control is simpler.

Definitive magnetic nasal prosthesis for partial nasal defect.

Maxillofacial trauma refers to any injury to the face or jaw caused by physical force, trauma, the presence of foreign objects, animal or human bites, and burns. Facial defects can be devastating in their impact on physical structure and function of the affected individual, leading to potential compromises in quality of life. Restoration of facial defects, especially nasal defects, is a difficult challenge for both the surgeon and the prosthodontist. Here is a case report of partial nasal defect caused by trauma, rehabilitated with a magnetic nasal prosthesis made with silicone elastomers using mechanical and anatomical retentive aids.

Consideraciones sobre el desgaste del polietileno en la artroplastia total de cadera / Considerations on polyethylene wear in jip total arthroplasty

INTRODUCCION: El desgaste del polietileno ha sido un problema desde la introducción de la artroplastia total de baja fricción y continua siéndolo en la actualidad en lo que influyen múltiples condiciones. OBJETIVO: Describir las consideraciones técnicas necesarias en la artroplastia total de cadera en aras de garantizar la mayor durabilidad de sus componentes. MÉTODOS: Se realiza una revisión de la literatura publicada al respecto tomándose en cuenta las variables que afectan el desgaste del polietileno así como las maniobras técnicas que pueden ser realizadas por el cirujano en aras de optimizar la durabilidad de los componentes protésicos. RESULTADOS: La inclinación de la cúpula mayor de 45º está directamente relacionada con el desgaste del polietileno. La restauración del centro de rotación de la cadera con el centro de rotación de la cúpula ha sido un importante objetivo en la técnica de cementación del acetábulo debido a reportes de su relación con el desgaste. La cobertura por el hueso es importante para evitar el pinzamiento del cuello de metal contra el polietileno o el anillo de metal de la cúpula. CONCLUSIÓN: El cirujano puede cambiar el centro de rotación del acetábulo para obtener una óptima inclinación y cobertura de forma segura sin que implique un incremento de la incidencia del efecto adverso de desgaste

INTRODUCTION: The polyethylene wear has been a problem from the introduction of low fraction total arthroplasty until nowadays where influencing many conditions. OBJECTIVE: To describe the technical conditions needed in the total hip arthroplasty to guarantee a greater durability of its components. METHODS: Literature published on this subject is reviewed taking into account the variables affecting the polyethylene wear as well as the possible technical manoeuvres carried out by surgeon to optimize the durability of prosthetic components. RESULTS: The 45º slope of major cupula is directly related to polyethylene wear. Restoration of the hip rotation center with the cupula rotation center has been a significant objective in acetabulum cementation due to reports of its relation to wear. The bone coverage is important to avoid the metal neck clamping against the polyethylene or the metal ring of cupula. CONCLUSION: The surgeon may to change the acetabulum rotation center to achieve an optimal and safe slope and coverage without an increase of incidence of wear adverse effect

Restoration of an atrophic eye socket with custom made eye prosthesis, utilizing digital photography.

Ocular defects may cause several ocular and orbital disorders, which require surgical intervention. These defects are psychologically disturbing for the patients, and therefore, they require immediate management and rehabilitation by a team of specialist. Ocular prosthesis may be either readymade (stock) or custom made. Fabrication of a custom ocular prosthesis allows for a range of variations during construction. The iris can also be custom made by ocular painting or by digital photography. The optimum cosmetic and functional results of a custom-made prosthesis enhance the patient's rehabilitation to a normal life style. This paper elaborates the technique for fabrication of a custom-made ocular prosthesis for an atrophic eye socket utilizing digital photography.

Ocular prosthesis: art meets science / Prótese ocular: a arte encontra a ciência

Objective: To describe a method of fabricating of ocular prosthesis. Discussion: The conventionalmethod of painting the iris region of a scleral prosthesis has been circumvented in this method. Fabricatingan ocular prosthesis by conventional methods requires painting the scleral region. Painting the cornealregion of the prosthesis is a tedious process. This article describes an easier, faster and a more aesthetictechnique of customizing an ocular prosthesis.

Objetivo: Descrever um método de fabricação de prótese ocular. Discussão: O método convencional de pintura(caracterização) da região da íris numa prótese escleral foi modifi cado neste método. A fabricação de prótese ocular pormétodos convencionais requer pintura da esclerótica. Pintar a região corneal da prótese é um processo tedioso. Esteartigo descreve uma maneira rápida, fácil e com resultados estéticos satisfatórios de customização de próteses oculares.

A simplified approach to fabrication of an ocular prosthesis: A case series.

The eye is a vital organ and an important component of facial expression. Loss of an eye has a crippling effect on the psychology of the patient. Enucleation of the eye is therefore normally followed by fabrication of an ocular prosthesis to improve esthetics. A less complex technique for fabrication of an ocular prosthesis is described in this report of two different cases.

A comparative study of "plasmacup" and "porous-coated" acetabular components: survival after 10 to 12 years of follow-up

OBJECTIVES: Our primary aim was to compare the long-term survivorship rates and the rates of successful osseointegration between two different types of uncemented acetabular components. INTRODUCTION: Two types of alloys have primarily been used for the manufacture of the uncemented acetabular components: titanium-based and cobalt-based alloys. A titanium-based alloy appears to be more effective with regard to interface stress transfer to the host bone because of its lower elastic modulus relative to a cobalt-based alloy. This supposed mechanical advantage of a titanium-based alloy component motivated this comparative study. METHODS: Two uncemented acetabular components, a porous-coated acetabulum and a Plasmacup®, were compared with a focus on long-term prosthesis survivorship and the development of acetabular osseointegration. Five radiographic signs of osseointegration were evaluated at the last follow-up appointment: (1) absence of radiolucent lines, (2) presence of a superolateral buttress, (3) medial stress-shielding, (4) radial trabeculae, and (5) an inferomedial buttress. We considered the presence of any three of these radiographic signs, in the absence of acetabular dislocation or symptoms, to be indicative of successful acetabular osseointegration. RESULTS: Among 70 patients implanted with the porous-coated acetabulum, 80 percent achieved osseointegration over a mean follow-up time of 11.9 years versus 75.3 percent of the 73 patients who received a Plasmacup insert over a mean of 10.7 years. Prosthesis survivorship rates were not different between the two groups. Revision surgery due to mild or severe acetabular osteolysis, polyethylene wear, and aseptic loosening occurred in eight patients (11.4 percent) with a PCA versus nine (12.3 percent) with a Plasmacup. CONCLUSIONS: We conclude that, during the first ten years after surgery, there is no significant difference between these two types of uncemented cups with regard to either prosthesis survivorship or successful osseointegration.

Modelo tridimensional de un fémur humano por medio del método del elemento finito / Tri-dimentional model of a human femur determined by the finite element method

El método del elemento finito nos permite observar la geometría del espécimen, las propiedades mecánicas de los materiales empleados y las condiciones de carga y frontera del modelo. Analizamos el fémur de un individuo masculino sano, de 27 años. Nuestra conclusión es que el fémur trabaja predominantemente en cargas de compresión y secundariamente en flexión.

The use of a modular titanium endoprosthesis in skeletal reconstructions after bone tumor resections: method presentation and analysis of 37 cases

We analyzed 37 patients who underwent segmental wide resection of bone tumors and reconstruction with a modular titanium endoprosthesis at the Orthopaedic Oncology Group, between 1992 and 1998. Twelve patients were male and 25 were female, with a mean age of 30 years (9 - 81). The mean follow-up was 14 months (2 - 48). The diagnoses were: steosarcoma (14 cases), metastatic carcinoma (10), Ewing's sarcoma (4), giant cell tumor (4), malignant fibrous histiocytoma (3), chondrosarcoma (1), and aneurysmal bone cyst (1). Eleven articulated total knee, 8 partial proximal femur with bipolar acetabulum, 8 partial proximal humerus, 3 total femur, 2 partial proximal tibia, 2 diaphyseal femur, 2 diaphyseal humerus, and 1 total proximal femur with cementless acetabulum endoprosthesis implant procedures were done. The complications related to the procedure included: infection (5 cases), dislocation (3), module loosening (1), and ulnar nerve paresthesia (1). We used the following criteria for the clinical evaluation: presence of pain, range of motion, reconstruction stability, surgical and oncologic complications, and patient acceptance. The results were good in 56.8 per cent of the cases, regular in 32.4 per cent and poor in 10.8 per cent.

Análise da passividade de adaptaçäo de infra-estruturas para prótese fixa implanto-suportada, através do uso de extensômetros / Analysis of the passive adaptation of suprastructures for fixed implant-supported prosthesis, by means of extensometries

A adaptaçäo passiva entre prótese e intermediário é considerada um requisito básico para o sucesso do tratamento protético em implantes osseointegrados, embora nenhuma definiçäo ou parâmetro foi estabelecido para descrever o que constitui uma adaptaçäo passiva. A mensuraçäo da qualidade de adaptaçäo das peças depende de vários fatores, como o método de avaliaçäo, das variáveis laboratoriais e, principalmente, de variáveis dependentes do operador como o aperto dos parafusos de fixaçäo, avaliaçäo clínica e a adaptaçäo propriamente dita dos componentes. O objetivo deste trabalho foi avaliar a passividade de adaptaçäo de infra-estruturas para prótese sobre implantes, em funçäo de dois tipos de ligas metálicas. Corpos de prova simulando uma situaçäo de prótese total fixa mandibular foram confeccionados em cobalto-cromo e paládio-prata, posicionados sobre um modelo mestre. Extensômetros foram fixados nas faces mesial e distal de cada intermediário para capturar a deformaçäo, quando os parafusos de fixaçäo eram apertados. Os dados obtidos foram submetidos ao teste Mann-Whitney para a análise estatística. Os resultados näo foram estatisticamente diferentes entre si, sendo verificado um nível de passividade similar entre as infra-estruturas fundidas em cobalto-cromo e em paládio-prata. Sugere-se a utilizaçäo de ligas em cobalto-cromo na realizaçäo de pesquisas clínicas