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Objective To evaluate a proposed three-dimensional (3D) printing process of a biomodel developed with the aid of fused deposition modeling (FDM) technology based on computed tomography (CT) scans of an individual with nonunion of a coronal femoral condyle fracture (Hoffa's fracture). Materials and Methods Thus, we used CT scans, which enable the evaluation of the 3D volumetric reconstruction of the anatomical model, as well as of the architecture and bone geometry of sites with complex anatomy, such as the joints. In addition, it enables the development of the virtual surgical planning (VSP) in a computer-aided design (CAD) software. This technology makes it possible to print full-scale anatomical models that can be used in surgical simulations for training and in the choice of the best placement of the implant according to the VSP. In the radiographic evaluation of the osteosynthesis of the Hoffa's fracture nonunion, we assessed the position of the implant in the 3D-printed anatomical model and in the patient's knee. Results The 3D-printed anatomical model showed geometric and morphological characteristics similar to those of the actual bone. The position of the implants in relation to the nonunion line and anatomical landmarks showed great accuracy in the comparison of the patient's knee with the 3D-printed anatomical model. Conclusion The use of the virtual anatomical model and the 3D-printed anatomical model with the additive manufacturing (AM) technology proved to be effective and useful in planning and performing the surgical treatment of Hoffa's fracture nonunion. Thus, it showed great accuracy in the reproducibility of the virtual surgical planning and the 3D-printed anatomical model.

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Abstract Objective To evaluate a proposed three-dimensional (3D) printing process of a biomodel developed with the aid of fused deposition modeling (FDM) technology based on computed tomography (CT) scans of an individual with nonunion of a coronal femoral condyle fracture (Hoffa's fracture). Materials and Methods Thus, we used CT scans, which enable the evaluation of the 3D volumetric reconstruction of the anatomical model, as well as of the architecture and bone geometry of sites with complex anatomy, such as the joints. In addition, it enables the development of the virtual surgical planning (VSP) in a computer-aided design (CAD) software. This technology makes it possible to print full-scale anatomical models that can be used in surgical simulations for training and in the choice of the best placement of the implant according to the VSP. In the radiographic evaluation of the osteosynthesis of the Hoffa's fracture nonunion, we assessed the position of the implant in the 3D-printed anatomical model and in the patient's knee. Results The 3D-printed anatomical model showed geometric and morphological characteristics similar to those of the actual bone. The position of the implants in relation to the nonunion line and anatomical landmarks showed great accuracy in the comparison of the patient's knee with the 3D-printed anatomical model. Conclusion The use of the virtual anatomical model and the 3D-printed anatomical model with the additive manufacturing (AM) technology proved to be effective and useful in planning and performing the surgical treatment of Hoffa's fracture nonunion. Thus, it showed great accuracy in the reproducibility of the virtual surgical planning and the 3D-printed anatomical model.

Resumo Objetivo Avaliar uma proposta de processo de impressão tridimensional (3D) de um biomodelo preparado com o auxílio da tecnologia de modelagem por deposição de material fundido (fused deposition modeling, FDM, em inglês) a partir de imagens de tomografia computadorizada (TC) de um indivíduo com pseudartrose de fratura coronal do côndilo femoral (fratura de Hoffa). Materiais e Métodos Para tanto, utilizamos imagens de TC, que permitem estudar a reconstrução volumétrica 3D do modelo anatômico, além da arquitetura e geometria óssea de sítios de anatomia complexa, como as articulações. Também permite o planejamento cirúrgico virtual (PCV) em um programa de desenho assistido por computador (computer-aided design, CAD, em inglês). Essa tecnologia possibilita a impressão de modelos anatômicos em escala real que podem ser utilizados em simulações cirúrgicas para o treinamento e a escolha do melhor posicionamento do implante de acordo com o PCV. Na avaliação radiográfica da osteossíntese da pseudartrose de Hoffa, verificou-se a posição do implante no modelo anatômico impresso em 3D e no joelho do paciente. Resultados O modelo anatômico impresso em 3D apresentou características geométricas e morfológicas semelhantes às do osso real. O posicionamento dos implantes em relação à linha de pseudartrose e pontos anatômicos foram bastante precisos na comparação do joelho do paciente com o modelo anatômico impresso em 3D. Conclusão A utilização do modelo anatômico virtual e do modelo anatômico impresso em 3D com a tecnologia de manufatura aditiva (MA) foi eficaz e auxiliou o planejamento e a realização do tratamento cirúrgico da pseudartrose da fratura de Hoffa. Desta forma, foi bastante preciso na reprodutibilidade do planejamento cirúrgico tanto virtual quanto no modelo anatômico impresso em 3D.

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INTRODUCTION: knee femoral condyle coronal fractures or Hoffa fractures are among the rarest fractures of the pelvic limb, being even more rare those of the medial condyle. The success in the management of these patients lies in the timely diagnosis and the consequent anatomical reduction of the femoral articular surface. CLINICAL CASE: the objective of this article is to present a patient with right medial Hoffa fracture, registered as a single case in the archives of our hospital. The patient was referred to us on November 2011, with a 10-day course after suffering a fall from horse ridding, presenting a forced varus mechanism and direct contusion of the right knee. He shows an anteroposterior and lateral knee X-rays showing a subtle solution of continuity in the coronal plane of the base of the medial condyle, corroborated with magnetic resonance imaging and was also associated with a non-surgical partial injury of both menisci and the anterior cruciate ligament. Surgical intervention was performed on 27th/11/2011, through open reduction with a medial approach and internal fixation with 7.0 mm (x2) cannulated screws. The patient was discharged with early and continuous mobilization of the knee, deferring support and rehabilitation until the 6th week. He is currently a wandering patient, asymptomatic, with complete range of motion. Because respecting the extensor apparatus through a medial approach and the articular surface with cannulated screws, it was observed in consequence an adequate evolution of our patient, being able to return to his daily activities, even remount.

INTRODUCCIÓN: las fracturas del cóndilo femoral en el plano coronal o fracturas de Hoffa se encuentran entre las fracturas más raras del miembro pélvico, pero son aún más raras las del cóndilo medial. El éxito en el manejo de estos pacientes radica en el diagnóstico oportuno y la consecuente reducción anatómica de la superficie articular del fémur. CASO CLÍNICO: el objetivo de este reporte es presentar a un paciente con el diagnóstico de fractura de Hoffa medial derecha, registrado como caso único en los archivos de nuestro hospital. El paciente acudió referido en Noviembre de 2011, con evolución de 10 días tras sufrir caída de caballo, presentando mecanismo de varo forzado y contusión directa de la rodilla derecha. Mostró radiografías anteroposterior y lateral de rodilla derecha, donde se observó de forma sutil solución de la continuidad en el plano coronal de la base del cóndilo medial, corroborado por resonancia magnética y asociado a lesiones parciales no quirúrgicas de ambos meniscos y del ligamento cruzado anterior. Se intervino quirúrgicamente el día 27 de Noviembre de 2011 mediante reducción abierta con abordaje medial y fijación interna con dos tornillos canulados de 7.0 mm. Se egresó al paciente indicando la movilización temprana y continua de la rodilla, difiriendo el apoyo y rehabilitación hasta la sexta semana. Actualmente el paciente se encuentra con posibilidad de deambulación, asintomático y con arcos de movilidad completos. El respeto del aparato extensor mediante un abordaje medial y la superficie articular con tornillos canulados se refleja en la adecuada evolución de nuestro paciente, pudiendo regresar a sus actividades diarias, incluso el montar.

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Resumen: Introducción: Las fracturas del cóndilo femoral en el plano coronal o fracturas de Hoffa se encuentran entre las fracturas más raras del miembro pélvico, pero son aún más raras las del cóndilo medial. El éxito en el manejo de estos pacientes radica en el diagnóstico oportuno y la consecuente reducción anatómica de la superficie articular del fémur. Caso clínico: El objetivo de este reporte es presentar a un paciente con el diagnóstico de fractura de Hoffa medial derecha, registrado como caso único en los archivos de nuestro hospital. El paciente acudió referido en Noviembre de 2011, con evolución de 10 días tras sufrir caída de caballo, presentando mecanismo de varo forzado y contusión directa de la rodilla derecha. Mostró radiografías anteroposterior y lateral de rodilla derecha, donde se observó de forma sutil solución de la continuidad en el plano coronal de la base del cóndilo medial, corroborado por resonancia magnética y asociado a lesiones parciales no quirúrgicas de ambos meniscos y del ligamento cruzado anterior. Se intervino quirúrgicamente el día 27 de Noviembre de 2011 mediante reducción abierta con abordaje medial y fijación interna con dos tornillos canulados de 7.0 mm. Se egresó al paciente indicando la movilización temprana y continua de la rodilla, difiriendo el apoyo y rehabilitación hasta la sexta semana. Actualmente el paciente se encuentra con posibilidad de deambulación, asintomático y con arcos de movilidad completos. El respeto del aparato extensor mediante un abordaje medial y la superficie articular con tornillos canulados se refleja en la adecuada evolución de nuestro paciente, pudiendo regresar a sus actividades diarias, incluso el montar.

Abstract: Introduction: Knee femoral condyle coronal fractures or Hoffa fractures are among the rarest fractures of the pelvic limb, being even more rare those of the medial condyle. The success in the management of these patients lies in the timely diagnosis and the consequent anatomical reduction of the femoral articular surface. Clinical case: The objective of this article is to present a patient with right medial Hoffa fracture, registered as a single case in the archives of our hospital. The patient was referred to us on November 2011, with a 10-day course after suffering a fall from horse ridding, presenting a forced varus mechanism and direct contusion of the right knee. He shows an anteroposterior and lateral knee X-rays showing a subtle solution of continuity in the coronal plane of the base of the medial condyle, corroborated with magnetic resonance imaging and was also associated with a non-surgical partial injury of both menisci and the anterior cruciate ligament. Surgical intervention was performed on 27th/11/2011, through open reduction with a medial approach and internal fixation with 7.0 mm (x2) cannulated screws. The patient was discharged with early and continuous mobilization of the knee, deferring support and rehabilitation until the 6th week. He is currently a wandering patient, asymptomatic, with complete range of motion. Because respecting the extensor apparatus through a medial approach and the articular surface with cannulated screws, it was observed in consequence an adequate evolution of our patient, being able to return to his daily activities, even remount.

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BACKGROUND: Correct management of Hoffa fractures is a challenge in the clinical context. Open reduction along with internal fixation should be the therapy of choice. Mechanical trials with the main internal fixation systems conducted by individualized finite element (FEM) models, to date, have been neglected. The aim of this study was to biomechanically analyze four fixation methods for the treatment of Type II Hoffa fracture (OTA Classification: 33B3.2∗ lateral) using FEM. METHODS: Four internal fixators were developed to treat Type II Hoffa fracture using finite elements: 4.5 mm cortical screws and 7 mm cannulated screw in anterior-to-posterior and posterior-to-anterior directions (4.5AP, 4.5 PA, 7AP and 7 PA). Under the same conditions, fractural deviation in the vertical, maximum and minimum principal and Von Mises directions in the syntheses used were evaluated. RESULTS: The vertical displacements evaluated were 0.7 mm, 0.5 mm, 0.8 mm and 0.3 mm; the values of maximum were 6.14 Mpa, 6.15 hPa, 6.0 Mpa and 6.2 Mpa, the values obtained from minimum data were 6.26 Mpa, -6.45 Mpa, -7.3 MPa and -6.8 Mpa and the maximum values of Von Mises peak stress were 185.0 Mpa, 194.1 Mpa, 143.6 Mpa and 741.4 Mpa, for the fixation models 4.5AP, 4.5 PA, 7AP and 7 PA, respectively. CONCLUSION: The 7 mm-cannulated screw fixation system yielded the best mechanical results evaluated by FEM in the treatment of Type II Hoffa fracture, causing a decrease in vertical displacement when used in retrograde and in Von Mises peak stress in anterograde.

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Osteoarthritis (OA) is the gradual loss of articular cartilage and involves several tissues, such as the synovial membrane, meniscus, ligaments, and adipose tissue known as Hoffa fat pad. There are largely unexplored factors that lead to OA development, such as the impact of exposure to heavy metals like cadmium (Cd) on the viability of cells in the knee joint tissue. The objective of this report was to identify the cell type with the highest susceptibility to Cd toxicity with respect to cell viability and death. Our findings showed that a concentration as low as 3 µM cadmium chloride for 12 h affects the viability of synovial cells, and a concentration of 10 µM affects Hoffa cells. Our results suggest that Cd can affect the viability of synovial and chondral cells primarily. In contrast, Hoffa cells were less susceptible, likely because Cd favors the production of pro-inflammatory cytokines before triggering their death as part of its damage mechanism at the articular level.

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Las fracturas de tercio distal de fémur unicondilares en el plano coronal son conocidas como fracturas de Hoffa, son poco frecuentes y muy raras. Se han reportado pocos casos este tipo de fracturas, por definición son fracturas inestables y por lo tanto requieren de resolución quirúrgica. El mecanismo de trauma en este tipo de fracturas es directo con la rodilla en flexión. Muchas veces pueden pasar desapercibidas en las proyección radiográficas anteroposterior (AP), y por eso es importante evaluar la proyección lateral. Cuando se sospechan o se evidencian es necesario tomar una tomografía axial computarizada (TAC) con el fin de definir claramente su su resolución quirúrgica, puesto que el abordaje y el método de fijación es controversial. Aunque hoy en día ha aumentado la disponibilidad y las características delos diferentes tipos de implantes, no hay un consenso en la literatura debido principalmente a la falta de experticia en estos poco frecuentes casos.

Unicondylar coronal plane fractures of the distal third of the femur are known as Hoffa fractures, are uncommon and rather rare. Only few cases of this type of fracture have been reported worldwide. By definition they are unstable fractures and therefore require surgical resolution. The mechanism of trauma in this type of fracture is an anterior to posterior direct trauma with a flexed knee. They can often go unnoticed on the anterior-posterior (AP) radiographic projection, so it is important to carefully evaluate the lateral projection. When they are suspected or perhaps evident, it is necessary to perform a computerized axial tomography (CT) in order to clearly define both, the characteristics of the fracture itself as the surgical resolution options, since the approach and the fixation method are controversial. Although nowadays the availability and characteristics of the different types of implants have increased, there is no consensus about the way to manage these fractures in medical literature, mainly due to the lack of expertise in these rare cases.

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Las fracturas de los cóndilos femorales en el plano coronal (Hoffa), son lesiones que afectan directamente la biomecánica de la rodilla. Están expuestas a un factor intrínseco de inestabilidad causado por el compromiso de los ligamentos y tendones insertados al fragmento condilar fracturado y a un factor extrínseco de inestabilidad dependiente del estrés mecánico en varo/valgo durante la fase de apoyo de la marcha y movimientos de flexo-extensión. El tratamiento quirúrgico con tornillos canulados sólo permite la compresión interfragmentaria y cierto grado de estabilidad rotacional, sin embargo, ese tipo de fijación podría no ser suficiente para soportar o neutralizar las cargas. Distintos autores han publicado otros métodos de osteosíntesis con el uso de placas en el plano lateral o posterior más la colocación de tornillos en sentido postero-anterior, pero siguen siendo opciones controversiales debido al tipo de morbilidad inherente a cada constructo. El objetivo de este artículo es realizar una revisión de la literatura para analizar la validez de los principios quirúrgicos y biomecánicos en el tratamiento de fracturas tipo hoffa.

Coronal plane fractures of the femoral condyles are commonly known as Hoffa fractures. These are intraarticular fractures that directly affect the biomechanics of the knee and have intrinsic and extrinsic instability patterns. The tendons and ligaments that remain attached to the condylar fragment produce the intrinsic instability. The extrinsic instability is due to the varus/valgus stress applied during the stance phase in the gait cycle as well as the flexion-extension movements. Surgical treatment with cannulated screws only achieves interfragmentary compression and certain amount of rotational stability that is not enough to support or neutralize the loads. Some authors have published different methods of osteosynthesis with lateral or posterior plates in conjunction with screws implanted in the posterior-anterior direction, still these techniques remain controversial due to the morbidity inherent to each construct. The purpose of this article is to review the current concepts of Hoffa fractures including biomechanics and surgical principles with the intention of analyzing their treatment efficacy.

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This study addresses a topic that was previously unaddressed in the literature: the normal sonographic appearance of the Hoffa's fat pad (HFP) in young, asymptomatic subjects. The aim of the study is to describe the sonoanatomical features of HFP, including its echostructure, echogenicity, elasticity, and vascularization, in subjects without knee pathology. Knees of healthy subjects were examined with grayscale ultrasound (US) to determine the sonographic characteristics of the HFP. Echogenicity was assessed by pixel intensity quantification. Vascularity was evaluated by color Doppler (CD) US. Elasticity of the adipose tissue was examined by sonoelastography. The absence of HFP pathology was confirmed clinically in all participants and by magnetic resonance imaging in randomly selected participants. Seventy-two knees from 36 subjects were assessed. The HFP presented a characteristic well-defined two-layered echostructure: the superficial adipose tissue was hypoechoic with respect to the nearby patellar tendon and contained septae, whereas the deeper layer was homogeneously hypoechoic and lacked connective tissue septae. Echogenicity differed between the superficial and deeper layers (the deeper layer was brighter), suggesting that the degree of acoustic impedance differed between layers. CD detected blood flow in 55.5% of HFPs. The superficial HFP layer presented greater elasticity than the deeper HFP layer (88.8 vs. 75.3 Kpa; p < .001). Our study provides a comprehensive description of the normal sonographic features of the HFP, which is useful to increase the potential of US for the discrimination of pathological findings involving this anatomical area.

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Introducción: La grasa infrapatelar de Hoffa es una inclusión infraarticular presente en la rodilla y existen evidencias que células multipotentes están presentes en tejido adiposo del humano adulto. Objetivo: El propósito de este trabajo es aislar e identificar células mesenquimales a partir de muestras de la grasa de Hoffa tomadas de pacientes a los que se les practicó cirugía de rodilla que expongan este tejido. Metodología: Una vez obtenido el consentimiento informado de un total de 12 pacientes, se obtuvo la muestra de tejido graso. La grasa fue disgregada incubándola en colagenasa en PBS a 37ºC y con agitación, luego se inactivó con suero fetal bovino, se separaron mediante centrifugación los adipocitos maduros de las células multipotentes y se obtuvieron las muestras para sembrar en medio Mesencult. Una porción de muestra fue utilizada para identificación mediante citometría de flujo y otra parte para ser coloreada con azul de metileno. Resultados y Discusión: Tanto en las tinciones con azul de metileno como en los cultivos celulares se han apreciado células con la morfología propia de una célula mesenquimal en forma de estrella y que fueron corroborados mediante citometría de flujo para los marcadores CD13, CD29, CD59 y CD105; igualmente hemos podido observar la efectividad del tratamiento enzimático. Conclusiones: En la actualidad nos encontramos consolidando los cultivos primarios para posteriormente diferenciarlos en líneas celulares específicas que puedan ser utilizadas en estudios de patologías, tales como obesidad, diabetes y trastornos articulares...

Introduction: The infrapatellar fat pad (sometimes know Hoffa's pad) is a soft tissue that lies beneath the patella (kneecap) separating it from the femoral condyle. There is evidence suggesting the presence of stem cells on adipose tissue in the adult human. Objective: The purpose of this work is to isolate and identify grown stem cells from Hoffa's fat samples obtained from patients undergoing surgeries exposing this tissue. Materials and Methods: After obtaining informed consent, the biopsy of Hoff's fat pad was obtained. The samples were incubated with collagenase and PBS a 37ºC and agitated, then it was inactivated with fetal bovine serum and centrifuged, washed twice with PBS, the pellet was resuspended and one part was cultivated on Mesencult medium the other part was used for flow cytometry and stained with methylene blue for morphologic analysis. Also before and after the enzyme digestion, the samples were added to 10% formaldehyde to evaluate the collagenase treatment. Results and analysis: The results show the effectiveness of the enzymatic treatment, the architecture of the adipose tissue was lost. The star shape stem cells morphology was appreciated with methylene blue in the cultures, it was corroborated by flow cytometry with CD13, CD29, CD59 and CD 105 markers. Conclusions: Primary cultures are consolidating, the next aim will be to obtain differentiated specific cell types that can be use in the study of obesity, diabetes and articular illnesses...

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Las fracturas distales del fémur representan solamente el 6 por ciento de todas las fracturas femorales. Presentamos el caso de un paciente masculino de 42 años que sufrió accidente del transito, que le provocó fractura unicondilar del extremo distal del fémur en el plano coronal, conocida como fractura de Hoffa. Se muestra el tratamiento quirúrgico realizado mediante estudios radiológicos, donde se utilizó tornillo del sistema AO. Con este tipo de proceder se obtuvo reducción y estabilidad de la fractura. Se concluye que una planificación preoperatorio adecuada es necesaria para obtener resultados satisfactorios.

Femoral distal fractures accounts for only the 6 percent of all femoral ones. Authors present the case of a male patient aged 42 suffered a road accident provoking a unicondylar fracture of femur distal end in coronal plane , known as Hoffa fracture. Surgical treatment by radiological studies is showed, where we used a screw of AO system. Using this procedure we achieved the fracture reduction and stability. We conclude that an appropriate preoperative planning is necessary to get satisfactory results.

Les fractures distales du fémur ne représentent que 6 percent de toutes les fractures fémorales. Dans ce travail, le cas d'un patient âgé de 42 ans, ayant souffert un accident de la route qui lui a provoqué une fracture condylienne de l'extrémité distale du fémur sur le plan coronal, connue par fracture d'Hoffa, est présenté. Un traitement chirurgical basé sur des études radiologiques, et dans lequel une vis du système AO est utilisée, est exposé. On a constaté une réduction et une stabilité de la fracture grâce à cette procédure. On peut conclure qu'une planification préopératoire est nécessaire pour obtenir des résultats satisfaisants dans ces cas.