RESUMO

The increase of revision surgeries in hip replacement procedure in Colombian young adult population can be addressed by a new design of femoral stem that reduces stress shielding. A new femoral stem was designed using topology optimization as a design aid to reduce the mass in the femoral stem and its overall stiffness, combined with the theoretical, computational, and experimental assessment of the new design that complies with a static and fatigue safety factor greater than one. The new femoral stem design can be used as a design tool to reduce the number of revision surgeries caused by stress shielding.

RESUMO

The endurance properties of a femoral stem under fatigue loading must be known and the methodology proposed in this work provides the mathematical tools for designers of femoral stems and orthopedic surgeons to select the adequate material and femoral stem design with a new graph that condensate the information in an easy to use selection process. Initially, the theoretical and computational development of the fatigue analysis provides comparable results with an average error of 8.3%. And the formulated methodology with the aim of selecting the mechanical device with the best fatigue performance with an average error of 8.7%.

Assuntos

RESUMO

BACKGROUND: The ExeterTM Universal cemented femoral component is widely used for total hip replacement surgery. Although there have been few reports of femoral component fracture, removal of a broken femoral stem can be a challenging procedure. CASE SUMMARY: A 54-year-old man with a Dorr A femur sustained a refracture of a primary ExeterTM stem, two years after receiving a revision using a cement-within-cement technique (CWC) through an extended trochanteric osteotomy (ETO). The technical problems related to the CWC technique and the ETO played a major role in the stem fatigue refracture. We performed revision surgery and removed the distal cement using a cortical femoral window technique, followed by re-implantation with an uncemented, modular, distally-fixed uncemented stem. The patient experienced an uneventful postoperative recovery. CONCLUSION: Re-fracture of a modern femoral ExeterTM stem is a rare event, but technical complications related to revision surgery can lead to this outcome. The cortical window osteotomy technique can facilitate the removal of a broken stem and cement, allowing for prosthetic re-implantation under direct vision and avoiding ETO-related complications.

RESUMO

Total hip arthroplasty (THA) is a safe and effective procedure in patients with end-stage ostheoarthritis. In the last years the indication for THA is increasingly in younger patients, associated with rising of life expectancy, this imply an increase in revision surgeries for various causes such as: aseptic loosening, fractures and infections. In this context and in view of the need to replace the femoral component, alternatives to the classic extended trochanteric osteotomy (ETO) arise, such as the anterior cortical window (ACW), which allows the rate of complications to be reduced with excellent results. We present the case of a 51-year-old patient who sustained one episode of dislocation, who required revision surgery due to aseptic loosenig, where the ACW was used for the extraction of the stem. In addition, a review of the literature was made to show advantages and complications regarding ETO.

Assuntos

RESUMO

The maximum stresses on a femoral stem must be known for selecting the right size and shape of the shaft cross-sectional area for reducing the stress shielding effect generated after the total hip arthroplasty (THA) surgical procedure. The methodology proposed in this study provides the tools to the designers of femoral stems and orthopedic surgeons to select the adequate femoral stem cross section, decreasing the stiffness of the stem, thus reducing the stress shielding effect in the patient bones. The first contribution is the theoretical development of the maximum static stress calculation for 12 different femoral stem models with the beam theory, followed by the comparison with the static finite element analysis (FEA) simulations and finally the experimental corroboration of one femoral stem model measuring the strain with linear strain gages and transform it to stresses, the three different approaches provide comparable results, with a maximum average error of less than 8.5%. The second contribution is the formulation of a new selection methodology based on maximum stresses in the femoral stem and the cross section area for decreasing the stress shielding effect, optimizing the area needed for withstand the loads and decreasing the overall stiffens of the stem.

Assuntos

RESUMO

Total hip arthroplasty, one of the most successful orthopaedic procedures, is influenced by several variables. Corrosion at the modular junction is known as trunnionosis. Despite being reported infrequently, corrosion between the femoral head and the Morse taper can result in severe complications. Fracture of the femoral component in primary metal-on-metal (MoM) total hip arthroplasty at the Morse taper is an extremely rare event and can be associated with several risk factors. We report a case of corrosion at the Morse taper in a hybrid primary MoM total hip arthroplasty, resulting in Morse taper fracture with consequent femoral head entrapment inside the acetabular component. We hypothesise that some risk factors, such as age over 60years, active male patients, body mass index above 30kg/m2, large femoral heads, high-offset stems, 9/10 Morse taper and MoM-bearing surfaces, are associated with this mode of failure.

Assuntos

RESUMO

Abstract Total Hip Arthroplasty (THA) is one of the surgical procedures carried out satisfactorily in procedures for osteoarthritis and trauma lesions. ATC surgery reduces pain and improves the quality of life of young patients. Therefore, it is of great importance to improve the properties of hip implants, since current implants do not match their lifespan with the life expectancy of a young patient. This is because the solid prostheses that currently exist have a higher Young's modulus, and therefore are too rigid compared to the bone tissue. On the other hand, the cyclic and continuous loads to which the hip joint is subjected in daily activities, can cause loosening and consequent implant loss The present work proposes an implant manufactured with a porous lattice structure, which aims to reduce stiffness, allow bone growth and a more effective mechanical load transfer. Three computational models subjected to static charges were evaluated and compared: 1) healthy femur, 2) implanted femur with a commercial prosthesis, and 3) implanted femur with a prosthesis with lattice structure. For the computational analysis it was decided to perform a static analysis of a person standing on the left foot; a load equivalent to the body weight was applied on the head of the femur, balancing the reaction forces in the system of forces (contact force, body weight, and abductor muscle).. The results were shown in terms of displacement, compression and deformation. The model implanted with a prosthesis with a lattice design presented a slight decrease in displacement, and a decrease in compression and deformation values, which indicated that the proposed design has a better distribution and transport of the loads through its structure.

Resumen La artroplastia total de cadera (ATC) es uno de los tratamientos quirúrgicos llevados a cabo de manera satisfactoria en procedimientos para la osteoartritis y lesiones de trauma. La ATC reduce el dolor y mejora la calidad de vida de los pacientes. Por lo tanto, es de gran importancia mejorar las propiedades de los implantes de cadera, ya que los implantes actuales tienen un tiempo de vida útil y deben cumplir con las expectativas de rehabilitación para los pacientes. Esto se debe a que las prótesis sólidas que existen actualmente tienen un módulo de Young más elevado, y por lo tanto son demasiado rígidas a comparación del tejido óseo. Por otro lado, las cargas cíclicas y continuas a las que se ve sometida la articulación de la cadera en actividades diarias, pueden ser causa del aflojamiento y consecuente pérdida del implante. El presente trabajo propone un implante fabricado con una estructura porosa tipo látice, el cual tiene como objetivos reducir la rigidez, permitir crecimiento óseo y una transferencia de cargas mecánicas más efectiva. Se evaluaron y compararon tres modelos computacionales sometidos a cargas estáticas: 1) fémur sano, 2) fémur implantado con una prótesis comercial, y 3) fémur implantado con una prótesis con estructura látice. Para el modelo computacional se optó por hacer un análisis estático de una persona parada sobre el pie izquierdo; donde se aplicó una carga equivalente del peso corporal sobre la cabeza del fémur, equilibrando las fuerzas de reacción en el sistema de fuerzas (fuerza de contacto, peso corporal, y músculo abductor). Los resultados fueron mostrados en términos de desplazamiento, compresión y deformación. El modelo implantado con una prótesis con un diseño tipo látice presentó una ligera disminución de desplazamiento, y disminución en los valores de compresión y deformación, lo que indicó que el diseño propuesto posee una mejor distribución y transporte de las cargas a través de su estructura.

RESUMO

The clinical case of an 80-year-old female who suffered three fractures in uncemented stems implanted in her right hip in a period of three years is presented. A fracture occurred in the prosthetic neck and the other two at the juncture of the conical and cylindrical stem portion, coinciding with the metaphyseal-diaphyseal junction of the femur. The main causes of the failure were an increasing concentration of forces at the level of the implant as a consequence of the increased length of the neck and lateralization of the femur (offset). Other causes that have contributed to this prosthetic failure are analyzed.

Se presenta el caso clínico de una paciente de 80 años que sufrió tres roturas de vástagos protésicos no cementados implantados en su cadera derecha en un período de tres años. Una rotura ocurrió en el cuello protésico y las otras dos en la unión de la porción cónica y cilíndrica del vástago, coincidiendo con la zona metafiso-diafisaria del fémur. La causas principales del fallo han sido un incremento de la concentración de fuerzas a nivel del implante como consecuencia del aumento de la longitud del cuello y de la lateralización femoral (offset). Se analizan otras causas que han podido contribuir a dicho fallo protésico.

Assuntos

RESUMO

Introducción: Ante el difícil y cada vez más frecuente escenario de una revisión de cadera, existen diferentes alternativas para conseguir una fijación estable y duradera del componente femoral. El objetivo de este estudio fue evaluar la evolución clínica y radiográfica de los pacientes sometidos a una revisión del componente femoral con tallo cilíndrico de superficie rugosa extendida. Materiales y Métodos: Se llevó a cabo un estudio multicéntrico y retrospectivo de 148 pacientes, operados entre marzo de 1997 y marzo de 2010, a quienes se les realizó una cirugía de revisión femoral con un tallo cilíndrico con recubrimiento poroso. La edad promedio era de 63.1 años. Resultados: El seguimiento promedio fue de 7.7 años. En 134 (89,9%) pacientes, se observó una fijación ósea estable; en 12 (8%), una fijación fibrosa estable y, en 3 (2%), una fijación fibrosa inestable. El puntaje de Harris se modificó de 41 en el preoperatorio a 92 después de la cirugía. Las complicaciones fueron infección profunda (2 casos, 1,3%), fractura de fémur intraoperatoria (12,8%) y luxación protésica (3 casos, 2%). Conclusión: Los tallos cilíndricos con recubrimiento poroso han demostrado ser un eficaz recurso para solucionar la mayoría de las revisiones femorales por la posibilidad de obtener fijación estable a corto y largo plazo. Nivel de Evidencia: IV

Introduction: In the set of hip revision surgery there are different options to achieve a stable fixation of the femoral component. The objective of this study was to evaluate the clinical and radiographic outcomes of patients who underwent hip revision with cylindrical extensively porous stem. Methods: Between March 1997 and March 2010 a multicenter retrospective study was performed in 148 patients who underwent hip revision with cylindrical extensively porous stem. The mean age was 63.1 years. Results: The follow-up was 7.7 years. One hundred thirty-four (89.9%) patients achieved a stable bone ingrowth fixation; 12 (8%) a stable fibrous fixation and 3 (2%) a non-stable fixation. The Harris Hip Score improved from 41 points before surgery to 92 points in the postoperative period. Complications included: two deep infections (1.3%), 12 intra-operative femoral fractures (8%) and three hip dislocations (2%). Conclusion: The cylindrical extensively porous femoral stem seems to be a reliable technique for femoral hip revision surgery, as it is possible to obtain a short- and long-term stable fixation. Level of Evidence: IV

Assuntos

RESUMO

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 hip arthoplasty prosthesis for Indonesian population. This was an anthropometric study conducted on sex matched 100 healthy Indonesian mongoloid race subjects based on Computer Tomographic (CT) imaging on the proximal femur. The parameters being used in this study were Femoral Head Offset (FHO), Femoral Head Position (FHP), Femoral Head Diameter (FHD), Neck-Shaft Angle (NSA), Anteroposterior Width (APW) and Mediolateral Width at 3 different locations, and Canal Flare Index (CFI). This study showed that Indonesian has smaller proximal femur morphometry as compared to Western population. The mean value of all parameters in male were larger than female. Moreover, FHO and FHP showed significant difference among male and female indicating the location of male femoral head center lies superiorly as compared to female. The dimension of femoral canal was found to be mediolaterally oval, 1.43, 1.28, and 1,34, respectively, in 3 different cutting (20 mm above and 40 mm below lesser trochanter, and isthmus). CFI of Indonesian was classified to be stovepipe femoral canal (2.99) that is the suggestion to use cemented femoral stem. This study showed that Indonesian proximal femur dimension has smaller build compared with Western counterpart. The proposed dimensions can be used as the basic data to design the ideal size of the femoral stem for Indonesian population.

Para diseñar prótesis a medida en una población determinada, la morfometría necesita ser conocida. El objetivo de este estudio fue obtener resultados que sean útiles en la investigación para diseñar el tamaño ideal de una prótesis total de artroplastía de cadera para la población de Indonesia. Fue realizado un estudio antropométrico en 100 sujetos sanos de raza mongoloide de Indonesia, en los que se estudió la parte proximal del fémur por tomografía computadorizada (TC). Se consideraron como parámetros la cabeza del fémur (CF), posición de la cabeza del fémur (PCF), diámetro de la cabeza del fémur (DCF), ángulo cérvicodiafisario (ACD), ancho anteroposterior (AAP) y ancho-lateral en 3 lugares diferentes. La población Indonesia tiene una morfometría menor del fémur proximal en comparación con la población occidental. El valor medio de todos los parámetros en hombres fueron mayores a las mujeres. Por otra parte, CF y PCF mostraron diferencia significativa entre hombres y mujeres e indicó una ubicación superior del centro de la cabeza del fémur en hombres, en comparación con las mujeres. Se encontró que la dimensión del canal femoral fue mediolateral oval, 1,43, 1,28, y 1,34, en 3 cortes diferentes, respectivamente (20 mm superior y 40 mm inferior del trocánter menor e istmo). La dimensión del fémur proximal en la población de Indonesia es de menor tamaño en comparación con la contraparte occidental. Las dimensiones propuestas se pueden utilizar como datos básicos para el diseño de un tamaño ideal de vástago femoral para la población Indonesia.

Assuntos

RESUMO

Resumen: Se presenta el caso clínico de una paciente de 80 años que sufrió tres roturas de vástagos protésicos no cementados implantados en su cadera derecha en un período de tres años. Una rotura ocurrió en el cuello protésico y las otras dos en la unión de la porción cónica y cilíndrica del vástago, coincidiendo con la zona metafiso-diafisaria del fémur. La causas principales del fallo han sido un incremento de la concentración de fuerzas a nivel del implante como consecuencia del aumento de la longitud del cuello y de la lateralización femoral (offset). Se analizan otras causas que han podido contribuir a dicho fallo protésico.

Abstract: The clinical case of an 80-year-old female who suffered three fractures in uncemented stems implanted in her right hip in a period of three years is presented. A fracture occurred in the prosthetic neck and the other two at the juncture of the conical and cylindrical stem portion, coinciding with the metaphyseal-diaphyseal junction of the femur. The main causes of the failure were an increasing concentration of forces at the level of the implant as a consequence of the increased length of the neck and lateralization of the femur (offset). Other causes that have contributed to this prosthetic failure are analyzed.

Assuntos

RESUMO

Introducción: El objetivo de este estudio retrospectivo fue observar el comportamiento de un tallo modular de fijación proximal y anclaje distal en revisiones de cadera con defectos femorales II y IIIA (Paprosky), evaluando la estabilidad protésica y articular, la restauración del offset y la diferencia de longitud. Materiales y Métodos: Se analizaron 22 revisiones de reemplazos totales de cadera. Doce mujeres y 10 hombres (edad promedio 62.38 años). El seguimiento promedio fue de 62 meses. El tallo femoral utilizado fue S-ROM® (Depuy, Johnson & Johnson). Los defectos óseos femorales fueron 15 de tipo II y 7 de tipo IIIA de Paprosky. Para la evaluación clínica se utilizó el puntaje de cadera de Harris. En las radiografías, se analizó el comportamiento del tallo, su integración, la diferencia de longitud y el offset femoral, y se consideró correcta una diferencia <5 mm. Resultados: El offset fue restaurado en 16 (72,3%) casos y la longitud de miembros se restauró en 15 (68,2%). Hubo un solo hundimiento del tallo, y de acuerdo con la clasificación de Engh, se observaron 17 (77,27%) uniones óseas. Se produjeron siete (31,8%) complicaciones, dos luxaciones que requirieron revisión, cuatro fracturas intraoperatorias y una paresia de ciático poplíteo externo. Conclusiones: Este tallo impresiona ser una alternativa válida para resolver un problema complejo. Por su versatilidad, permite resolver mecánicamente el defecto óseo, devuelve la longitud al miembro y el offset a la articulación, con un índice de complicaciones aceptables.

Background: The purpose of this retrospective analysis was to observe the outcomes of a modular hip system in revision total hip arthroplasty with Paprosky types II and IIIA femoral bone defects, evaluating their performance, offset restoration and leg length discrepancy correction. Methods: Twenty-two revision total hip arthroplasties were analyzed in 12 women and 10 men (average age 62.38 years). The average follow-up was 62 months. Femoral stems S-ROM® (Depuy, Johnson & Johnson) were used. Paprosky femoral bone deficit were 15 types II and 7 IIIA. Clinical evaluation was performed using the Harris Hip Score, while Engh lassification was used for stem fixation. Offset restoration, leg length discrepancy (a difference <5 mm was considered correct) and hip stability were evaluated radiographically. Results: Offset was properly restored in 16 (72.3%) cases and the leg length was matched in 15 (68.2%). There was a single stem subsidence and according to Engh classification, proximal bone ingrowth fixation was obtained in 17 (77.27%) patients. There were 7 (31.8%) complications: two dislocations that required revision, four intraoperative fractures and a lateral popliteal nerve paresis. Conclusions: S-ROM® modular system seems to be a valid alternative to solve a complex problem. Its versatility allows to optimize hip stability, leg length equalization and offset restoration in revision total hip arthroplasty, showing an acceptable complication rate.

Assuntos