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David S Ruch - One of the best experts on this subject based on the ideXlab platform.
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metacarpal position and lunate facet Screw fixation in dorsal wrist spanning bridge plates for intra articular distal radial fracture a biomechanical analysis
Journal of Bone and Joint Surgery American Volume, 2020Co-Authors: Evan M Guerrero, Alexander Lauder, Andrew E Federer, Richard R Glisson, Marc J Richard, David S RuchAbstract:BACKGROUND A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet Locking Screw was also evaluated. METHODS A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a Locking Screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p < 0.008) were performed to assess differences in fragment stability between groups. RESULTS The average fracture displacement at 300 N was 0.8 mm in Group 1, 0.4 mm in Group 2, and 0.2 mm in Group 3. Plating to the third metacarpal more effectively resisted displacement compared with the second metacarpal at all axial loads (p < 0.008). The addition of a lunate facet Screw further stiffened the construct at loads of ≥200 N (p < 0.008). CONCLUSIONS Plate fixation to the third metacarpal with an intrafragmentary Screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups. CLINICAL RELEVANCE The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary Screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary Screws to increase stability in DWSP fixation.
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metacarpal position and lunate facet Screw fixation in dorsal wrist spanning bridge plates for intra articular distal radial fracture a biomechanical analysis
Journal of Bone and Joint Surgery American Volume, 2020Co-Authors: Evan M Guerrero, Alexander Lauder, Andrew E Federer, Richard R Glisson, Marc J Richard, David S RuchAbstract:BACKGROUND: A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet Locking Screw was also evaluated. METHODS: A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a Locking Screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p /=200 N (p < 0.008). CONCLUSIONS: Plate fixation to the third metacarpal with an intrafragmentary Screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups. CLINICAL RELEVANCE: The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary Screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary Screws to increase stability in DWSP fixation.
Jerome Noailly - One of the best experts on this subject based on the ideXlab platform.
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fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing a computational exploration
International Orthopaedics, 2016Co-Authors: Io Carrera, Pablo Eduardo Gelbe, Gaeta Chary, Miguel Angel Gonzalezballeste, Juan Carlos Monllau, Jerome NoaillyAbstract:Purpose To assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated Screws or with a Locking plate in a split fracture of the lateral tibial plateau (LTP).
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fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing a computational exploration
International Orthopaedics, 2016Co-Authors: Ion Carrera, Juan Carlos Monllau, Pablo Eduardo Gelber, Gaetan Chary, Miguel Angel Gonzalezballester, Jerome NoaillyAbstract:To assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated Screws or with a Locking plate in a split fracture of the lateral tibial plateau (LTP). A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A Locking Screw plate (LP) and a cannulated Screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated. While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated Screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. Split fractures of the LTP fixed either with Locking Screw plate or cannulated Screws showed no clinically relevant IFM in a FE model. The Locking Screw plate showed higher mechanical stability than cannulated Screw fixation. The Locking Screw plate might also allow full or at least partial weight bearing under static posture at time zero.
Evan M Guerrero - One of the best experts on this subject based on the ideXlab platform.
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metacarpal position and lunate facet Screw fixation in dorsal wrist spanning bridge plates for intra articular distal radial fracture a biomechanical analysis
Journal of Bone and Joint Surgery American Volume, 2020Co-Authors: Evan M Guerrero, Alexander Lauder, Andrew E Federer, Richard R Glisson, Marc J Richard, David S RuchAbstract:BACKGROUND A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet Locking Screw was also evaluated. METHODS A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a Locking Screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p < 0.008) were performed to assess differences in fragment stability between groups. RESULTS The average fracture displacement at 300 N was 0.8 mm in Group 1, 0.4 mm in Group 2, and 0.2 mm in Group 3. Plating to the third metacarpal more effectively resisted displacement compared with the second metacarpal at all axial loads (p < 0.008). The addition of a lunate facet Screw further stiffened the construct at loads of ≥200 N (p < 0.008). CONCLUSIONS Plate fixation to the third metacarpal with an intrafragmentary Screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups. CLINICAL RELEVANCE The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary Screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary Screws to increase stability in DWSP fixation.
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metacarpal position and lunate facet Screw fixation in dorsal wrist spanning bridge plates for intra articular distal radial fracture a biomechanical analysis
Journal of Bone and Joint Surgery American Volume, 2020Co-Authors: Evan M Guerrero, Alexander Lauder, Andrew E Federer, Richard R Glisson, Marc J Richard, David S RuchAbstract:BACKGROUND: A dorsal wrist-spanning plate (DWSP) can be affixed to the second or third metacarpal, depending on the morphology of the distal radial fracture (DRF) and on surgeon preference, but comparative biomechanical analyses between these methods are limited. This biomechanical study compared fixation to the second metacarpal versus the third metacarpal as measured by lunate facet fragment displacement in a cadaveric model of an axially loaded intra-articular DRF. The construct rigidity with the addition of an intrafragmentary lunate facet Locking Screw was also evaluated. METHODS: A sample size of 14 cadaveric matched pairs was calculated to achieve 81.7% power. The 28 limbs were randomized to DWSP fixation to the second metacarpal (Group 1) or third metacarpal (Group 2); each wrist underwent an osteotomy simulating an unstable intra-articular DRF. Limbs were tested at axial loads of 50, 100, 150, 200, 250, and 300 N. Lunate facet displacement from the metaphyseal fragment at each load was measured with use of differential variable reluctance transducers. After initial testing, a Locking Screw was placed through the plate into the lunate facet fragment in the third metacarpal group (Group 3). Displacement measurements were repeated for all loads. Paired 2-tailed t tests with Bonferroni correction (significance, p /=200 N (p < 0.008). CONCLUSIONS: Plate fixation to the third metacarpal with an intrafragmentary Screw was the most biomechanically favorable construct, although other factors may favor an alternative distal fixation site. Mean displacement of the lunate facet fragment at 300 N was <1 mm in all groups. CLINICAL RELEVANCE: The present study demonstrated that a DWSP affixed to the third metacarpal with an intrafragmentary Screw provides the most effective stabilization of the lunate facet fragment in intra-articular DRFs. This study validates the use of intrafragmentary Screws to increase stability in DWSP fixation.
Herwig Drobetz - One of the best experts on this subject based on the ideXlab platform.
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multidirectional volar fixed angle plating using cancellous Locking Screws for distal radius fractures evaluation of three Screw configurations in an extra articular fracture model
Wiener Klinische Wochenschrift, 2011Co-Authors: Patrick Weninger, Herwig Drobetz, Heinz Redl, Enrico Dallara, Wolfgang Nemec, Markus Figl, Harald Hertz, Philippe K ZyssetAbstract:INTRODUCTION: Volar fixed-angle plating is a popular treatment for unstable distal radius fractures. Despite the availability of plating systems for treating distal radius fractures, little is known about the mechanical properties of multidirectional fixed-angle plates. The aim of this study was to compare the primary fixation stability of three possible Screw configurations in a distal extra-articular fracture model using a multidirectional fixed-angle plate with metaphyseal cancellous Screws distally. MATERIAL AND METHODS: Eighteen Sawbones radii (Sawbones, Sweden, model# 1027) were used to simulate an extra-articular distal radius fracture according to AO/OTA 23 A3. Plates were fixed to the shaft with one non-Locking Screw in the oval hole and two Locking Screws as recommended by the manufacturer. Three groups (n = 6) were defined by Screw configuration in the distal metaphyseal fragment: Group 1: distal row of Screws only; Group 2: 2 rows of Screws, parallel insertion; Group 3: 2 rows of Screws, proximal Screws inserted with 30° of inclination. Specimens underwent mechanical testing under axial compression within the elastic range and load controlled between 20 N and 200 N at a rate of 40 N/s. Axial stiffness and type of construct failure were recorded. RESULTS: There was no difference regarding axial stiffness between the three groups. In every specimen, failure of the Sawbone-implant-construct occurred as plastic bending of the volar titanium plate when the dorsal wedge was closed. DISCUSSION: Considering the limitations of the study, the recommendation to use two rows of Screws or to place Screws in the proximal metaphyseal row with inclination cannot be supported by our mechanical data.
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influence of an additional Locking Screw on fracture reduction after volar fixed angle plating introduction of the protection Screw in an extra articular distal radius fracture model
Journal of Trauma-injury Infection and Critical Care, 2009Co-Authors: Patrick Weninger, Herwig Drobetz, Michael Schueller, Michael Jamek, Heinz Redl, E K TscheggAbstract:BACKGROUND: Though, volar fixed-angle plating has become increasingly popular to treat distal radius fractures no studies are available comparing the mechanical properties of different Screw configurations to fix the plate to the shaft. The aim of the present study was to evaluate the effect of an additional Locking Screw directly proximal to the fracture site and to assess if such a Screw might be protective against secondary loss of reduction after volar fixed-angle plating. METHODS: Ten Sawbones radii were used to simulate an extra-articular distal radius fracture model (AO/OTA 23-A3). In the first group (n = 5), volar fixed-angle plates (Aptus Radius 2.5, Medartis, Switzerland) were fixed to the radius shaft with a single nonLocking cortex Screw in the oval hole and with two Locking Screws in the holes proximal to the long hole (LLNx); in the second group, the plates were fixed identically as in the first group, but an additional Locking Screw was inserted into the plate-hole distal to the oval hole, proximal to the fracture site (LLNL). After embedding, specimens were tested with a servohydaulic material testing machine under cyclic axial loading with 800 N for 2,000 cycles. Axial stiffness, elastic axial deformation (elastic dorsal tilt angle), and plastic deformation (plastic dorsal tilt angle) were recorded. RESULTS: After 2,000 cycles, stiffness was 761.6 (+/-59.5) N/mm in group LLNx and 628.9 (+/-37.6) N/mm in group LLNL without significant difference. Elastic deformation and elastic tilt angle were 1.05 (+/-0.08) mm and 3.9 (+/-0.3) degree in group LLNx. In group LLNL, elastic deformation and elastic tilt angle were 1.27 (+/-0.08) mm and 4.7 (+/-0.3) degree, respectively. Plastic deformation and plastic tilt angle were significantly higher in group LLNx (p < 0.001). After 2,000 cycles, dorsal tilt angle was 1.9 (+/-0.3) degree in group LLNx and 0.7 (+/-1.0) in group LLNL. CONCLUSION: This study showed the mechanical superiority of volar fixed-angle plates with a "protection Screw" in an extra-articular fracture model. Further clinical investigation is needed to verify the results.
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osteosynthesis of distal radial fractures with a volar Locking Screw plate system
International Orthopaedics, 2003Co-Authors: Herwig Drobetz, E KutschalissbergAbstract:We developed a Locking Screw plate system for the stabilisation of distal radial fractures, which can be inserted through a standard volar approach and in which the Locking mechanism allows early post-operative mobilisation. Forty-nine patients with 50 fractures underwent surgical treatment; 66% were type C fractures. The mean follow-up was 26 months. According to the scores of Gartland and Werley and Green and O'Brien, 92% and 68% respectively had an excellent or good outcome; 46% were radiologically identical to the uninjured side and in 42% the reduction remained unchanged after 2 years. The most frequent complication was rupture of the flexor pollicis longus tendon, which occurred in six cases (12%) at a mean of 10 months after operation.
Carrera Fernandez Ion - One of the best experts on this subject based on the ideXlab platform.
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Investigación de la biomecánica y mecanobiología de las fracturas de la meseta tibial mediante un modelo de elementos finitos
'Universitat Autonoma de Barcelona', 2017Co-Authors: Carrera Fernandez IonAbstract:Las fracturas de la meseta tibial afectan a una gran articulación de carga como es la rodilla y son lesiones graves que conducen frecuentemente a anomalías funcionales. Para preservar la función normal de la rodilla, se debe mantener la congruencia articular, conservar el eje mecánico normal, asegurar la estabilidad de la fractura y recuperar el rango de movilidad completo. Alcanzar estos objetivos presenta dificultades por la importante afectación de tejidos blandos, los distintos tipos de calidad ósea y, en ocasiones, la presencia de comorbilidades de los pacientes. El mecanismo de lesión principal que da lugar a las fracturas de la meseta tibial es una tensión en varo o valgo con una carga axial asociada. La meseta lateral resulta afectada en el 55%-70% de los casos, mientras que la medial se ve afectada en el 10%-30%. Todavía no existe una práctica totalmente estandarizada en las fracturas de la meseta tibial debido a la falta de estudios biomecánicos concluyentes, y coexisten diferentes técnicas usadas para el tratamiento de estas fracturas. Tener un mejor conocimiento biomecánico de las fracturas de la meseta tibial y comparar los tratamientos más utilizados ha sido uno de los objetivos principales de esta investigación para intentar dar respuesta a la pregunta de cuál es el mejor método para tratarlas. La base de esta investigación ha sido el uso del método de elementos finitos (EF) para el estudio de las fracturas de meseta tibial y sus tratamientos. Este método consiste en subdividir geometrías complejas en un ensamblado discreto de elementos de geometría sencilla en los que los desplazamientos relativos de puntos pueden ser fácilmente calculados en función de las cargas que se ejercen sobre el elemento. Según la dimensión del problema, estos elementos podrán ser líneas (1D), triángulos o cuadrados (2D), o tetraedros o hexaedros (3D). Los desplazamientos relativos de puntos calculados dentro de los elementos están asociados a valores de tensiones vía la introducción de ecuaciones de comportamiento para el material del elemento virtualmente constituido. El objetivo del primer trabajo (Fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing: a computational exploration) fue evaluar con cálculos de EF si la carga inmediata de peso sería posible tras la estabilización quirúrgica, ya sea con tornillos canulados o con una placa bloqueada en una fractura de la meseta tibial lateral. El segundo trabajo (An intact fibula may contribute to allow early weight-bearing in surgically treated tibial plateau fractures) intenta dar respuesta a la estabilidad que el peroné proximal aporta en las fracturas de la meseta tibial lateral. Se realizó un modelo de geometría tridimensional mediante elementos finitos a partir de la base de datos VAKHUM (http://www.ulb.ac.be/project/vakhum) y se creó una reconstrucción del modelo a partir de las imágenes de tomografía computarizada. Posteriormente se simuló una fractura tipo de meseta tibial lateral usando datos geométricos a partir de imágenes radiológicas y de TC. Se simularon los sistemas de tratamiento, con y sin peroné, la placa bloqueada Polyax® (Biomet Inc, IN, USA) y un set de tornillos canulados de 6,5 mm (Biomet Inc, IN, USA). Las fracturas de la meseta tibial lateral, fijadas ya sea con placa bloqueadas o con tornillos canulados, no mostraron movimientos interfragmentarios clínicamente relevantes en un modelo de EF. La fijación de la fractura con una placa bloqueada mostró una mayor estabilidad mecánica que la fijación con tornillos canulados. La placa bloqueada podría también permitir una capacidad de carga completa o al menos parcial bajo postura estática. Este modelo de EF mostró que un peroné intacto podría contribuir a la estabilidad mecánica de las fracturas de la meseta tibial lateral, y combinado con placa, la integridad mecánica que aporta el peroné puede permitir una capacidad de carga temprana y sin movimientos interfragmentarios significativos.Tibial plateau fractures affect to the knee joint and they are injuries that often cause functional impairment. To preserve the normal function of the knee, articular congruence must be achieved, stable fixation must be obtained as well as physiological knee aligment in order to recover full range of motion. This goals are often difficult to be achieved due to the soft tissue damage, bone quality and patient comorbidities. The most frecuent injury mechanism is an axial load of the knee combined with and excessive valgus or varus force. Lateral plateau is affected on 55%-70% of the cases and medial plateau on 10%-30%. There is not yet a totally standardized technique to approach all tibial plateau fractures due to the little number of biomechanic studies, therefore there are diferent techniques to treat the same fractures. The aim of this study was to have a better biomechanic understanding of tibial plateau fractures and to compare the most common treatments to asses what is the best way to treat these injuries. This investigation was conducted using finite elements (FE). FE method consists on subdividing complex geometries in a less complex geometry element assemblement. Therefore relative movements in the geometry can be easily measured and accurate calculations can be obtained. Depending on the dimension of the geometry studied the elements can be linear (1D), triangles or squares (2D)or tetrahedrons or hexahedrons (3D). Relative displacements of calculated points inside the elements are associated to tension values with behavioral equations for virtually simulated material and geometry. The purpose of the first study (Fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing: a computational exploration) was to assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated Screws or with a Locking plate in a split fracture of the lateral tibial plateau (LTP). The purpose of the second study ( An intact fibula may contribute to allow early weight-bearing in surgically treated tibial plateau fractures ) was to assess differences in interfragmentary movement (IFM) in a split fracture of lateral tibial plateau, with and without intact fibula. It was hypothesized that an intact fibula could positively contribute to the mechanical stabilization of surgically reduced lateral tibial plateau fractures. A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A Locking Screw plate (LP) and a cannulated Screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated with and without fibula. While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated Screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. Split fractures of the LTP fixed either with Locking Screw plate or cannulated Screws showed no clinically relevant IFM in a FE model. The Locking Screw plate showed higher mechanical stability than cannulated Screw fixation. The Locking Screw plate might also allow full or at least partial weight bearing under static posture at time zero. This FE model showed that an intact fibula contributes to the mechanical stability of the lateral tibial plateau. In combination with a Locking plate fixation, early weight bearing may be allowed without significant IFM, contributing to an early clinical and functional recovery of the patient
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Investigación de la biomecánica y mecanobiología de las fracturas de la meseta tibial mediante un modelo de elementos finitos
2017Co-Authors: Carrera Fernandez Ion, Universitat Autònoma De Barcelona. Departament De CirurgiaAbstract:Premi Extraordinari de Doctorat concedit pels programes de doctorat de la UAB per curs acadèmic 2016-2017Las fracturas de la meseta tibial afectan a una gran articulación de carga como es la rodilla y son lesiones graves que conducen frecuentemente a anomalías funcionales. Para preservar la función normal de la rodilla, se debe mantener la congruencia articular, conservar el eje mecánico normal, asegurar la estabilidad de la fractura y recuperar el rango de movilidad completo. Alcanzar estos objetivos presenta dificultades por la importante afectación de tejidos blandos, los distintos tipos de calidad ósea y, en ocasiones, la presencia de comorbilidades de los pacientes. El mecanismo de lesión principal que da lugar a las fracturas de la meseta tibial es una tensión en varo o valgo con una carga axial asociada. La meseta lateral resulta afectada en el 55%-70% de los casos, mientras que la medial se ve afectada en el 10%-30%. Todavía no existe una práctica totalmente estandarizada en las fracturas de la meseta tibial debido a la falta de estudios biomecánicos concluyentes, y coexisten diferentes técnicas usadas para el tratamiento de estas fracturas. Tener un mejor conocimiento biomecánico de las fracturas de la meseta tibial y comparar los tratamientos más utilizados ha sido uno de los objetivos principales de esta investigación para intentar dar respuesta a la pregunta de cuál es el mejor método para tratarlas. La base de esta investigación ha sido el uso del método de elementos finitos (EF) para el estudio de las fracturas de meseta tibial y sus tratamientos. Este método consiste en subdividir geometrías complejas en un ensamblado discreto de elementos de geometría sencilla en los que los desplazamientos relativos de puntos pueden ser fácilmente calculados en función de las cargas que se ejercen sobre el elemento. Según la dimensión del problema, estos elementos podrán ser líneas (1D), triángulos o cuadrados (2D), o tetraedros o hexaedros (3D). Los desplazamientos relativos de puntos calculados dentro de los elementos están asociados a valores de tensiones vía la introducción de ecuaciones de comportamiento para el material del elemento virtualmente constituido. El objetivo del primer trabajo (Fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing: a computational exploration) fue evaluar con cálculos de EF si la carga inmediata de peso sería posible tras la estabilización quirúrgica, ya sea con tornillos canulados o con una placa bloqueada en una fractura de la meseta tibial lateral. El segundo trabajo (An intact fibula may contribute to allow early weight-bearing in surgically treated tibial plateau fractures) intenta dar respuesta a la estabilidad que el peroné proximal aporta en las fracturas de la meseta tibial lateral. Se realizó un modelo de geometría tridimensional mediante elementos finitos a partir de la base de datos VAKHUM (http://www.ulb.ac.be/project/vakhum) y se creó una reconstrucción del modelo a partir de las imágenes de tomografía computarizada. Posteriormente se simuló una fractura tipo de meseta tibial lateral usando datos geométricos a partir de imágenes radiológicas y de TC. Se simularon los sistemas de tratamiento, con y sin peroné, la placa bloqueada Polyax® (Biomet Inc, IN, USA) y un set de tornillos canulados de 6,5 mm (Biomet Inc, IN, USA). Las fracturas de la meseta tibial lateral, fijadas ya sea con placa bloqueadas o con tornillos canulados, no mostraron movimientos interfragmentarios clínicamente relevantes en un modelo de EF. La fijación de la fractura con una placa bloqueada mostró una mayor estabilidad mecánica que la fijación con tornillos canulados. La placa bloqueada podría también permitir una capacidad de carga completa o al menos parcial bajo postura estática. Este modelo de EF mostró que un peroné intacto podría contribuir a la estabilidad mecánica de las fracturas de la meseta tibial lateral, y combinado con placa, la integridad mecánica que aporta el peroné puede permitir una capacidad de carga temprana y sin movimientos interfragmentarios significativos.Tibial plateau fractures affect to the knee joint and they are injuries that often cause functional impairment. To preserve the normal function of the knee, articular congruence must be achieved, stable fixation must be obtained as well as physiological knee aligment in order to recover full range of motion. This goals are often difficult to be achieved due to the soft tissue damage, bone quality and patient comorbidities. The most frecuent injury mechanism is an axial load of the knee combined with and excessive valgus or varus force. Lateral plateau is affected on 55%-70% of the cases and medial plateau on 10%-30%. There is not yet a totally standardized technique to approach all tibial plateau fractures due to the little number of biomechanic studies, therefore there are diferent techniques to treat the same fractures. The aim of this study was to have a better biomechanic understanding of tibial plateau fractures and to compare the most common treatments to asses what is the best way to treat these injuries. This investigation was conducted using finite elements (FE). FE method consists on subdividing complex geometries in a less complex geometry element assemblement. Therefore relative movements in the geometry can be easily measured and accurate calculations can be obtained. Depending on the dimension of the geometry studied the elements can be linear (1D), triangles or squares (2D)or tetrahedrons or hexahedrons (3D). Relative displacements of calculated points inside the elements are associated to tension values with behavioral equations for virtually simulated material and geometry. The purpose of the first study (Fixation of a split fracture of the lateral tibial plateau with a Locking Screw plate instead of cannulated Screws would allow early weight bearing: a computational exploration) was to assess, with finite element (FE) calculations, whether immediate weight bearing would be possible after surgical stabilization either with cannulated Screws or with a Locking plate in a split fracture of the lateral tibial plateau (LTP). The purpose of the second study ( An intact fibula may contribute to allow early weight-bearing in surgically treated tibial plateau fractures ) was to assess differences in interfragmentary movement (IFM) in a split fracture of lateral tibial plateau, with and without intact fibula. It was hypothesized that an intact fibula could positively contribute to the mechanical stabilization of surgically reduced lateral tibial plateau fractures. A split fracture of the LTP was recreated in a FE model of a human tibia. A three-dimensional FE model geometry of a human femur-tibia system was obtained from the VAKHUM project database, and was built from CT images from a subject with normal bone morphologies and normal alignment. The mesh of the tibia was reconverted into a geometry of NURBS surfaces. A split fracture of the lateral tibial plateau was reproduced by using geometrical data from patient radiographs. A Locking Screw plate (LP) and a cannulated Screw (CS) systems were modelled to virtually reduce the fracture and 80 kg static body-weight was simulated with and without fibula. While the simulated body-weight led to clinically acceptable interfragmentary motion, possible traumatic bone shear stresses were predicted nearby the cannulated Screws. With a maximum estimation of about 1.7 MPa maximum bone shear stresses, the Polyax system might ensure more reasonable safety margins. Split fractures of the LTP fixed either with Locking Screw plate or cannulated Screws showed no clinically relevant IFM in a FE model. The Locking Screw plate showed higher mechanical stability than cannulated Screw fixation. The Locking Screw plate might also allow full or at least partial weight bearing under static posture at time zero. This FE model showed that an intact fibula contributes to the mechanical stability of the lateral tibial plateau. In combination with a Locking plate fixation, early weight bearing may be allowed without significant IFM, contributing to an early clinical and functional recovery of the patient
