17th Annual Meeting - European Orthopaedic Research Society

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Reservados todos los derechos. All rights reserved

Editor: E. Gómez-Barrena Co-editor: N. Bonsfills

ISBN: 978-84-691-2464-2 D.L.: xxxxxxx Impreso en Mozart Art SL Maquetado en Facing-bcn

Index

COMMITTEES ACKNOWLEDGMENT AND REVIEWERS ACKNOWLEDGMENT AND MODERATORS WELCOME ADDRESS WORKSHOPS

07 08 09 10 12

ORAL SESSIONS INVESCOT-EORS

13

ORAL SESSIONS EORS ORAL SESSION 1 - HIP IMPLANTS 1 ORAL SESSION 2 - HIP IMPLANTS 2 ORAL SESSION 3 - STEM CELLS ORAL SESSION 4 - TISSUE ENGINEERING ORAL SESSION 5 - HIP CLINICAL 1 ORAL SESSION 6 - HIP CLINICAL 2 ORAL SESSION 7 - BONE ORAL SESSION 8 - LIGAMENT AND TENDON ORAL SESSION 9 - HIP (OTHER) ORAL SESSION 10 - IMAGING ORAL SESSION 11 - SPINE ORAL SESSION 12 - GROWTH

26 29 35 43 48 54 60 67 71 74 82 88

ORAL SESSION 13 - GAIT AND KINEMATICS

140

ORAL SESSION 14 - BIOMATERIALS

147

ORAL SESSION 15- AWARD SESSION

153

ORAL SESSION 16 - KNEE IMPLANTS

158

ORAL SESSION 17 - KNEE SOFT TISSUES

165

ORAL SESSION 18 - SHOULDER 1

170

ORAL SESSION 19 - SHOULDER 2

176

ORAL SESSION 20 - CARTILAGE AND MENISCUS

179

ORAL SESSION 21 - HAND, WRIST, ELBOW, FRACTURES, OTHER

187

POSTER SESSIONS POSTER SESSION 1- SPINE

94

POSTER SESSION 2- SHOULDER

102

POSTER SESSION 3- TISSUE ENGINEERING AND BIOMATERIALS

107

POSTER SESSION 4- CLINICAL, GAIT, GROWTH

112

POSTER SESSION 5- KNEE

115

POSTER SESSION 6- BONE AND CARTILAGE

125

POSTER SESSION 7- LIGAMENT AND TENDON

134

POSTER SESSION 8- INFECTION

136

POSTER SESSION 9- HAND, FOOT, FRACTURES, TUMOR

196

POSTER SESSION 10- HIP

209

EORS 2008 · MADRID

6

Committees

LOCAL ORGANIZING COMMITTEE

EORS EXECUTIVE COMMITTEE

HONORARY CHAIR LUIS MUNUERA

PRESIDENT NICO VERDORNSCHOT

CHAIR ENRIQUE GÓMEZ BARRENA

VICE-PRESIDENT FLORIAN GOTTSAUNER-WOLF

MEMBERS LUIS FERRÁNDEZ PORTAL CARLOS BARRIOS JOSÉ CORDERO AMPUERO FRANCISCO FORRIOL ENRIQUE GIL GARAY DANIEL HERNÁNDEZ VAQUERO EORS EXECUTIVE COMMITTEE

SECRETARY GENERAL MICHIEL MULIER TEASURER DOMINIQUE PIOLETTI MEMBER-AT-LARGE MARK TAYLOR MEMBER-AT-LARGE WILTRUD RICHTER MEMBER-AT-LARGE NICOLA BALDINI MEMBER-AT-LARGE ENRIQUE GÓMEZ BARRENA

EORS 2008 · MADRID

Acknowledgments to reviewers

J.N. ARGENSON P. ASPENBERG N. BALDINI C. BARRIOS N. BONSFILLS-GARCIA P. BUMA E. CACERES E. CENNI J. CORDERO P. ESBRIT J. ESTEBAN F. FORRIOL E.GIL GARAY E.GÓMEZ BARRENA M.J. GOMEZ BENITO F.GOTTSAUNER-WOLF B. GRIMM D. HERNÁNDEZ VAQUERO R. HUISKES I. HVID T. KINNARI Y. KONTTINEN S. KURTZ L. R. MESEGUER-OLMO Y. MISSIRLIS M. MULIER P. PETERS M.A. PÉREZ ANSON D. PIOLETTI E. RAUSELL W. RICHTER A.SALINAS J .STEINMEYER W.SWIESZKOWSKI E. TANCK R. TREBSE N .VERDONSCHOT

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EORS 2008 · MADRID

Acknowledgments to moderators

P. N. C. N. E. E. J. M. P. J. F. G. F. E. F. B. G. D. M. F. L. M. M. D. E. W. J. R. A. N. P.

ASPENBERG BALDINI BARRIOS BONSFILLS CÁCERES CENNI CORDERO DOWNING ESBRIT ESTEBAN FORRIOL FRIEDL GARCÍA-ÁLVAREZ GÓMEZ-BARRENA GOTTSAUNER-WOLF GRIMM HANNINK HDEZ VAQUERO LOPEZ-FRANCO MARCO MESSEGUER MULIER PEREZ PIOLETTI RAUSELL RICHTER RUTTEN SENDEN TOOM VERDONSCHOT ZOLLINGER

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EORS 2008 · MADRID

WELCOME ADDRESS

Dear Colleagues, The 17th meeting of European Orthopaedic Research Society is taking place in Madrid in April 24-26, 2008. The local organizers chaired by Enrique Gómez Barrena have succeeded to find an excellent location and are preparing a very attractive social program. As you may know, this meeting is the first one that is organized in a bi-annual fashion. Hence, from now on EORS meetings are every two years and are organized independent from the EFORT. The EORS meetings provide a platform for clinicians, researchers and industry to discuss orthopaedic research, issues and innovations. We therefore invite all individuals that are working in this field to submit their abstract to the upcoming Madrid meeting. The deadline for abstract submission is December 1st, 2007.

We plan to have an excellent program with invited keynote speakers, instructural courses, podium and poster presentations. From the submitted abstracts two papers are awarded. The first one is the EORS-2008 award, which is pre-selected from the 5 highest-ranked abstracts. In a special award-session these 5 papers are presented and the best paper/presentation is awarded with the EORS-2008 award. The other award is the Göran Selvik Award which is selected from the five best ranked abstracts concerning radiographic methods and measurements. In addition, there are 3 poster awards that will be selected during the conference. Obviously Madrid needs no further introduction. It is very easy to reach from anywhere in Europe and offers an excellent transportation system. In addition, Madrid is a city with a living soul, with a unique history and many cultural high lights. Hence, a perfect city to organize a scientific meeting and combine it with a social visit. We very much like to welcome you in April 2008 at the 17th meeting of the EORS. Bienvenidos,

Nico Verdonschot PhD President of the European Orthopaedic Research Society

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EORS 2008 · MADRID

WELCOME ADDRESS

Dear Colleagues and Friends, On behalf of all the organization of this 17th Meeting of the European Orthopaedic Research Society, I would like to welcome you to Madrid. We have been working hard to prepare a very exciting meeting, both scientifically and socially, and this represents an important challenge after the success of Bolonia in 2006. An EORS Meeting is always an opportunity to interact from different backgrounds and different countries. Networking strengthens Europe, and the rich spectrum of research related to Orthopaedics offers both clinicians and basic researchers, from different origins but a shared interest in Orthopaedics, a complementary view in our field. The scientific progress needed to better understand, prevent, and treat the Orthopaedic injuries and diseases, together with new opportunities for innovation and evolution in our skills and resources to offer the best for our patients, are guiding the efforts of our Society all over Europe. With this in mind, we focused on the balance of a spread scientific program based on short presentations and fruitful discussions, but also learning opportunities for younger colleagues and interaction among groups. The participation of you, the researchers in Orthopaedics, both clinicians and non-clinicians, and the impressive progression of Orthopaedic Science based on the quality of your research, will set the interest and significance of the Meeting. For the unique Meeting that we are expecting, we look for providing an Academic scenario at the Campus of the Medical School of the “Universidad Autónoma de Madrid”, which offers outdoor and indoor facilities to enjoy the Spring in Madrid. Madrid’s impressive social opportunities will hopefully allow for a pleasant stay with us, from the visits to Museums and historic sites, to the peculiar gastronomy and spectacles. I am sure that your expectations will be met and you will find a rewarding Meeting in the scientific and social aspects. Welcome to Madrid.

Enrique Gómez-Barrena, MD PhD Chair, EORS 2008 Meeting

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EORS 2008 · MADRID

Invited lectures, Workshops INVITED LECTURES THURSDAY, April 24th 18:30 h- 19:00 h Room: Aula Magna Bone marrow stromal cells: in vitro expansion and interaction with biofunctionalised substrates for bone tissue engineering N. Baldini

FRIDAY, April 25th 13:30 h – 14:00 h

Room: Aula Magna

European FP7 research funding and networking C. Hernández E. Fernández SATURDAY, April 26th 09:00 h – 09:30 h Room: Aula Magna Biologic Strategies to Repair Lost bone Due to Periprosthetic Osteolysis: Bench to Bedside S.B. Goodman

Bone structure: the role of microCT Chair. P. Esbrit Introduction P. Esbrit Structure-function assessment in bone using microcomputed tomography H. van Lenthe Variations in Trabecular Microstructural Parameters and its Relationship with Biomechanical Properties S. Dapía Robleda

SATURDAY, April 26th 08:00 h- 09:00 h Room: Aula Magna Gait Analysis Chair: Estrella Rausell Methods in clinical motion anñaysis. Do we need to change our approach? B. Muller

WORKSHOPS FRIDAY, April 25th 08:00 h- 09:00 h

FRIDAY, April 25th 08:00 h- 09:00 h Room: Seminario 1

Gait Analysis based on internal sensors J. Favre Room: Aula Magna

Implant-related infection Chair: J. Esteban Introduction J. Esteban Genetics of biofilm development in the genus Staphylococcus. I. Spiliopoulou Immunohistopathological differences and similarities between septic and aseptic loosening Y. Konttinen

SATURDAY, April 26th 08:00 h- 09:00 h Room: Seminario 1 Regenerative Medicine The European Science Foundation "Regenerative Medicine" Research Network program Y. Konttinen Development of an artificial bone using fetal cell therapy. D. Pioletti Growth factors released by platelets in bone regeneration E. Cenni Production of TGF-beta3 and its use in cartilage tissue engineering Y. Konttinen

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ORAL SESSIONS INVESCOT - EORS Thursday, April 24th

EORS 2008 · MADRID ORAL SESSION INVESCOT Thursday, April 24th INVESCOT 001

ESTRATEGIAS PARA LA ESTABILIZACIÓN DINÁMICA ARTIFICIAL DE LA RODILLA CON LESIÓN DE LIGAMENTO CRUZADO ANTERIOR. ESTUDIO EXPERIMENTAL EN GATOS SOBRE ESTIMULACIÓN MUSCULAR N. Bonsfills García, Á. Núñez Molina, E- Gómez Barrena Hospital Universitario La Paz. Madrid

INTRODUCCIÓN En el control de la estabilidad articular, tanto la resistencia del músculo como la contracción muscular derivada del control neuromuscular son piezas fundamentales. En la rodilla con lesión del ligamento cruzado anterior (LCA), este control neuromuscular está alterado, por lo que puede ser necesaria su compensación mediante estimulación muscular. En este sentido, las bases de la Estimulación Funcional Eléctrica (FES) proponen dos estrategias de control articular: una primera que potencie la contracción agonista-antagonista, aumentando la resistencia del músculo, y una segunda que transmita el estímulo en el momento apropiado de manera eficaz, de forma similar a la actuación del sistema propioceptivo. Nuestra hipótesis es que la excesiva traslación tibial anterior (TTA) de la rodilla inestable por lesión del LCA puede ser controlada mediante estimulación eléctrica de cuádriceps e isquiotibiales, bien por aumento de la resistencia muscular, bien a través de una ! contracción ajustada en el tiempo. Nuestros objetivos son medir la reacción muscular (longitud de fibra) y la laxitud anterior de la rodilla (TTA), antes y después de la aplicación de un estímulo eléctrico a cuádriceps e isquiotibiales, observando además el efecto de la estimulación repetida sobre la laxitud articular. MATERIAL Y MÉTODO Se estudiaron 17 rodillas de gato común (Felis catus) bajo anestesia general para evitar la contracción muscular voluntaria. La longitud de fibra muscular se estudió mediante ultrasonomicrometría de los principales músculos periarticulares. La laxitud articular se midió a partir de registros de vídeo sobre el plano sagital de la rodilla. Se sometió a las extremidades a tracción tibial anterior con una fuerza de hasta 24,5 N antes y después de la sección experimental del LCA, tanto a 90º como a 30º de flexión. En las rodillas inestables, se siguió un protocolo de estimulación con trenes de pulsos cuadrados de 0,2 ms al inicio (pre-tracción) y al final de la tracción máxima (post-tracción), y se aplicaron series de 500 ms, 100 ms, y 20 ms. Para cada músculo se calculó su deformación normalizada y la pendiente de la misma, y su actividad eléctrica pre-estimulo. La TTA y la deformación del músculo se compararon entre los distintos grupos: rodillas normales, inestables,

14

Sala Pagoda 15:45 - 17:10 h O 001-010 con estimulación pre-tracción, y con estimulación posttracción, tanto en valores máximos como a lo largo del movimiento. El análisis estadístico se realizó mediante la prueba de ANOVA con prueba post-hoc de Tukey. Para ver el efecto de la estimulación repetida, se contabilizó el número de series de estimulación que recibía cada extremidad, y se comparó la TTA entre dos grupos con límite en 12 series de trenes mediante la prueba de Mann-Whitney. RESULTADOS En la rodilla inestable, se observó un aumento de la deformación relativa de cuádriceps e isquiotibiales, y, de forma más selectiva, de su pendiente de deformación, mostrando una resistencia menor a ser estirados. Con la estimulación a 500 ms, los valores de deformación muscular se aproximaron a los de las rodillas control, y los de su pendiente fueron incluso menores que éstos, sugiriendo un aumento de esa resistencia muscular. En cuanto a la respuesta mecánica, la TTA se controlaba con la estimulación experimental. Cuando el estímulo eléctrico se aplicaba al inicio de la tracción, los valores máximos de TTA no fueron diferentes a los de las rodillas normales, mientras que si se aplicaba al final de la tracción, la laxitud sólo se controlaba a 30º de flexión. A lo largo del movimiento de tracción, se observó cómo las rodillas inestables alcanzaban rápidamente el nivel de inestabilidad, que se conseguía controlar con los trenes de diferente duración cuando se aplicaban al inicio de la fuerza de tracción. Estos mismos trenes aplicados al final de la tracción anterior no conseguían provocar una contracción muscular capaz de reducir la laxitud articular de la misma forma. Por último, cuando se estudió el efecto de la estimulación repetida, se observó una tendencia a una menor laxitud de la rodilla con más series de estimulación, a 30º de flexión. CONCLUSIONES El estímulo sincronizado con la tracción favorece el control de la TTA dentro de límites normales en el momento en que se precisa, lo cual concuerda con la recuperación o sustitución del sistema propioceptivo. Por otro lado, el estiramiento muscular más lento de las rodillas estimuladas sugiere una resistencia aumentada del músculo a ser deformado con la fuerza de tracción tibial anterior, lo cual va a favor de un sistema siempre preparado con aumento del tono muscular de agonistas-antagonistas. Este estudio propone las bases de ambas estrategias en la rodilla, que serían por tanto aplicables para el control de la inestabilidad por lesión del LCA. A la vista de los resultados, la estimulación eléctrica de la rodilla resultaría más eficiente si se aplica en el momento apropiado, al mismo tiempo que su reiteración colaboraría en mantener la TTA dentro de la estabilidad.

EORS 2008 · MADRID INVESCOT 002

CURRENT DENSITY AND FIELD DISTRIBUTIONS IN DC ELECTRICAL FIELD STIMULATION FOR HUMAN SPINAL CORD INJURY E. Collazos Castro, G. Hernández-Labrado,J.L. Polo-Sanz, E. López-Dolado Laboratorio de Reparación Neural Hospital Nacional de Parapléjicos (SESCAM) Finca La Peraleda .Toledo, Spain.

INTRODUCTION Applied DC electrical fields (EFs) stimulate and direct axonal growth in animal models of spinal cord injury (SCI), and clinical trials are underway to establish their efficacy in humans. The electrostimulation system proposed for human use utilizes low amplitude (~ 500 μV/mm) EFs applied via indwelling electrodes placed outside the vertebral channel. Although this strategy prevents additional neural damage, the electrical resistivity of interposing tissues could reduce field intensity within the spinal cord below therapeutic range. MATERIAL AND METHOD Here we present a finite element model of electrical magnitudes in the human cervical spinal cord during voltage application through electrodes of varied sizes and locations. Field intensity, distribution and direction, together with current and charge densities were analyzed in normal and injury conditions. RESULTS The electrode placement had a profound effect on EF intensity and direction within the spinal cord, with electrodes located outside the vertebral channel producing very low EFs that would compromise their therapeutic effects. Furthermore, field gradients were not homogeneous and their direction changed substantially in different regions of the spinal cord. The use of larger electrodes or higher potentials increased the fields to therapeutic values, whereas circular electrodes produced much more homogeneous field gradients. Electrodes placed inside the vertebral channel produced therapeutic field intensities with lower applied voltages. In addition, when a circular electrode was placed surrounding the lesion site inside the vertebral channel, therapeutic EF values were obtained with half the applied voltage. CONCLUSIONS Finite element models of the human spinal cord are a powerful method to study current distribution and electrical field intensities within the spinal cord and may guide the optimization of electrostimulation systems for neural repair.

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EORS 2008 · MADRID INVESCOT 003

ANÁLISIS POR ELEMENTOS FINITOS DE LAS TENSIONES EN LA FISIS FEMORAL PROXIMAL EN ADOLESCENTES SANOS C. Barrios, M. J. Gómez-Benito, D. C. Botero, J. M. GarcíaAznar, M. Doblaré Unidad de Traumatología y Cirugía Ortopédica, Departamento de Cirugía, Facultad de Medicina, Universidad de Valencia Valencia

INTRODUCCIÓN En este trabajo, el modelo paramétrico del fémur proximal de un niño, propuesto recientemente por los autores1, se adapta a las medidas geométricas de la cadera de un grupo de adolescentes sin patología previa de cadera. El objetivo de este trabajo es determinar computacionalmente las tensiones sobre el cartílago fisario proximal del fémur sano en distintas actividades (subir escaleras, caminar y sentarse) y analizar si dichas tensiones varían en consonancia con las variaciones anatómicas consideradas dentro de la normalidad. MATERIAL Y MÉTODO Un grupo de 23 adolescentes sanos con una edad media de 12.2 años (10-15) fueron sometidos a un estudio radiológico convencional de la pelvis y ambas caderas. De acuerdo con la sistemática de valoración radiográfica propuesta por Barrios y cols2, se cuantificaron distintos parámetros geométricos de una de las caderas entre los que incluían el ángulo de inclinación fisaria, el ángulo cuello-diáfisis, el ángulo de intersección, el ancho del cuello femoral y de la fisis, la altura del trocánter mayor y el ángulo de inclinación posterior de la fisis en las Rx axiales. Las mediciones de cada sujeto fueron introducidas en el modelo paramétrico obteniendo modelos de elementos finitos específicos para cada caso. En cada modelo se simularon tres situaciones diferentes de carga mecánica: caminar, subir escaleras y sedentación. Las cargas aplicadas fueron proporcionales al peso de cada sujeto. Se estudió la distribución de tensiones de Tresca, von Misses y Rankine sobre el cartílago fisario. RESULTADOS La distribución de tensiones en el cartílago fisario muestra un patrón similar en todos los sujetos. Las mayores tensiones se obtuvieron en la simulación de subir escaleras. En ese estadio, el 61% del volumen del cartílago fisario soportaba tensiones menores de 1MPa y sólo un 10% de la superficie fisaria soportaba tensiones de von Mises mayores de 1.5MPa. Si se analizaban las tensiones de Tresca, estas cifras pasaban a ser del 46% del volumen de la placa (1.5MPa). La región solicitada por mayores tensiones es la zona más medial de la fisis tanto para tensiones de von Mises como de Tresca. Las tensiones en la placa fisaria estaban directamente correlacionadas con el ángulo de inclinación fisaria en Rx AP y el ángulo de inclinación posterior de la fisis en Rx axiales. Los sujetos con ángulo de intercesión 30%. All patellae were tested in a modified 4 – point bending environment, to a maximum load of 10,000N, in a customized designed jig. This method simulates the axial bending stress on the patella during knee flexion. All dimensions of the patellae were recorded including Depth of patella at bone resection and wall thickness adjacent to plug resection site. Results All patellae with a 0% bone bridge fractured (Ultimate Tensile Strength/UTS) at a mean Tensile Force of 5863N (Range 3140 – 8730N). There was a subgroup of incomplete fractures – extra-articular fractures – which fractured at 6542N (Range 5085 – 9180N). The remaining specimens failed to fracture. Comparing the UTS and the patellar dimensions, using Weibull’s Statistical Analysis we demonstrated that less than 60% bone plug resection carried a very low probability of fracture. Discussion This study demonstrates the safe criteria for bone – tendon graft harvesting from both the proximal and distal poles of the patella. With regards to a normal human patella, a 40% bone – bridge is approximately a 20mm bone – bridge. We conclude that the simultaneous harvesting of Bone – Patellar Tendon – Bone and Quadriceps Tendon – bone grafts from a patella has no significant increase in the fracture risk of the patella.

166

BIOMECHANICAL PROPERTIES OF FOUR METHODS OF FIXATION USED FOR HAMSTRING ACL GRAFTS Richard Goddard, David Yeoh, Bijay Singh, Julia Shelton, Michael Mowbray. Department of Orthopaedics, Conquest Hospital, St. Leonardson-Sea, East Sussex. TN37 7RD. [email protected]

Aims The aims of this study were to evaluate the biomechanical properties and mode of failure of 4 methods of fixation used for hamstring tendon ACL grafts. The fixation methods investigated included titanium round headed cannulated interference (RCI) screws, bioabsorbable RCI screws, Endobuttons and Bollard fixation. It has been previously shown that a 2 strand tailored equine tendonSoffix graft has equivalent biomechanical properties to a 4 strand human hamstring tendon-Soffix graft, therefore this model was used for the graft in the study.

Conclusion Titanium and bioabsorbable RCI screws provide poor initial fixation of tendon grafts used for ACL reconstruction, having significantly lower UTL’s than both Endobutton and Bollard fixation. Under cyclic loading titanium and bioabsorbable RCI screws fail rapidly due to progressive tendon slippage, whereas Bollards and Endobuttons survive cyclic loading. Both Bollard fixation and Endobuttons provide sufficiently high UTL’s and survive cyclic loading to allow early postoperative mobilisation and rehabilitation. Caution must be used in the early postoperative period when using interference screws to secure a hamstring tendon graft because progressive tendon slippage may result in excessive graft elongation and early clinical failure.

ORAL SESSIONS - SATURDAY

O-093

ORAL SESSION - FRIDAY

EORS 2008 · MADRID

Materials and Method 32 stifle joints were obtained from skeletally mature pigs, the soft tissues were removed and the ACL and PCL were sacrificed. Tibial tunnel preparation was standardised using the Mayday Rhino horn jig to accurately position a guide wire. An 8 mm cannulated reamer was then used over the guide wire to create the final tibial tunnel. A back radiusing device was then placed into the tibial tunnel to chamfer the posterior margin of the tunnel exit to prevent abrasion and fretting of the graft. A 2 strand equine tendon-Soffix graft was then introduced into the tibial tunnel and secured with one of the four fixation methods. The proximal part of the graft was attached to the cross head of the materials testing machine using the Soffix. Five of each method of fixation were tested mechanically to failure and three of each method were cyclically loaded for 1000 cycles between 5 to 150 N, followed by 2000 cycles at 50 to 450 N. Results The mean ultimate tensile loads (UTL) were: titanium RCI screw = 444 N, bioabsorbable RCI screw = 668 N, Endobutton = 999 N and Bollard = 1153 N. The mode of failure for all RCI screws involved tendon slippage past the screw. Two Endobutton failures were encountered and one Bollard pull out occurred. Under cyclic loading conditions the titanium and bioabsorbable RCI screws failed rapidly after several hundred 5 to 150 N cycles due to tendon graft damage and progressive slippage. Both the Bollards and Endobuttons survived 1500 cycles at 50 to 450 N, with less tendon slippage occurring.

167

EORS 2008 · MADRID ORAL SESSION - FRIDAY

O-094

IN-VIVO KINEMATIC QUANTIFICATION OF TRANSLATIONAL AND ROTATIONAL LAXITIES IN ANATOMICAL DOUBLE-BUNDLE ACL RECONSTRUCTION USING PIVOT-SHIFT TEST

Results and Discussion The differences in static laxity values before and after anatomical DB reconstruction is shown in fig. 1. All laxity were significantly reduced by the reconstruction (p0,05). In the clinical study, the mean time to union of the fracture was 6 months (2-28 months). According to the Mayo Elbow Performance Index (MEPI) most patients had a good or excellent outcome. No patients reported difficulty with activities of daily living. Physical capacity showed minimal loss of stability and strength. Six patients had their hardware removed. Conclusion Technical ease of application and advantageous features of the LCP -such as unicortical screw fixation and improved holding power in osteopenic bone- make it a good alternative implant for comminuted olecranon fractures.

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POSTER SESSIONS - SATURDAY

POSTER SESSIONS - FRIDAY

Materials and Methods In the biomechanical study, five matched pairs of cadaveric elbows were randomly assigned for fixation by either LCP or a conventional plating method. Specimens were mounted to a custom-made testing bench and subjected to cyclic loading until failure occurred while measuring gapping at the osteotomy site. In the clinical study, twenty-one patients treated with LCP for complex olecranon fractures had a mean follow up of 20 months (3-39 months) and functional and patient rated outcome were evaluated.

EORS 2008 · MADRID P-059

SIRT1 ACTIVATION INDUCES APOPTOSIS OF HUMAN OSTEOSARCOMA CELLS Yan Li*, Carl-Magnus Bäckesjö*, Lars-Arne Haldosén#, Urban Lindgren* * Department for Clinical science, Intervention and technology (CLINTEC), Division of Orthopedics, Karolinska University Hospital, Huddinge, Stockholm, Sweden # Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Stockholm, Sweden [email protected]

Introduction Recently, the longevity gene sirt1 was found to be highly expressed in several types of mammalian tumors (3). Upregulation of sirt1 expression has also been correlated with the developement of chemotherapy resistance in human osteosarcoma (1). The present study aimed to test the effects of sirt1 activation on growth and survival of osteosarcoma cells.

POSTER SESSIONS - FRIDAY

Materials and Methods Normal human osteoblast cell line HNOst and four osteosarcoma cell lines HOS, MG-63, SaOS-2 and U-2OS were used in the study. Cells were cultured in ]-MEM supplemented with 10% FBS, 1 mM L-glutamine and 100 g/ml gentamicin at 37°C in a humidified atmosphere containing 5% CO2. Sirt1 activation was mediated by two activators, resveratrol and isonicotinamide, as well as by nutritional restriction elicited by L-asparaginase. Cell growth was measured on cells growing in 96-well plates by WST-1 assay (Roche Molecular Biochemicals). Flow cytometric analysis of apoptosis was performed on cells culturing in 6 well plates after staining with Annexin-FITC and/or propium iodide using an Annexin V kit (Caltag Laboratories, Burlingame, CA, USA).

POSTER SESSIONS - SATURDAY

Results and discussion Instead of promoting cell survival, both resveratrol and isonicotinamide decreased cell growth and induced cell apoptosis dose dependently in all four osteosarcoma cell lines. Such inhibition effects on cell survival were relatively minor on normal human osteoblasts. Although the osteosarcoma cell lines responded variably to L-asparaginase alone the pro-apoptotic effects of resveratrol were significantly enhanced with the presence of L-asparaginase. Both resveratrol and isonicotinamide are activators of the mammalian nuclear NAD-dependent protein deacetylase sirt1. The mechanism of sirt1 activation by resveratrol is not known in detail but it has been proposed that, as for some other polyphenols with trans-stilbene structure, it induces a conformational change in sirt1, which lowers Km for both the acetylated substrate and NAD (2). Isonicotinamide was supposed to enhance sirt1 deacetylase activity by competing with naturally presented nicotinamide, which inhibits deacetylation by chemical reversal of a covalent reaction intermediate (5). Besides activation by potential agonists, sirt1 expression can also be up-regulated under nutritional stress (4). The enzyme L-asparaginase can deprive L-asparagine through hydrolysis of L-asparagine into L-aspartic acid and ammonia. Unlike normal tissue many tumors including 206

osteosarcoma has been shown to be lack of enough asparagine synthetase and have to rely on external sources of L-asparagine to keep up with their rapid growth (6). Thus, by addition of L-asparaginase the tumor cells would suffer more severe nutritional stress than normal tissue. We demonstrated herein that sirt1 activators elicited pro-apoptotic effects in osteosarcomas. We also supposed that induction of sirt1 overexpression by nutrition restriction could further enhance the sensitivity of osteosarcomas to sirt1 activators so as to magnify the antitumor effects. Further studies aimed to confirm the role of sirt1in the anti-osteosarcoma effects are undertaken now in our group. Although our study can not elucidate the complicated relationship between sirt1 and cancer development our results supported the hypothesis that sirt1 could be a potential target used in osteosarcoma chemotherapy. Summary Our results demonstrated that activation of sirt1 by resveratrol and isonicotinamide induced apoptosis of osteosarcoma cells. This anti-tumor effect can be further enhanced by nutritional restriction elicited by L-asparaginase. Our findings suggested sirt1 could be a potential target for future therapy of osteosarcoma. Reference 1. Chu, F., Chou, P. M., Zheng, X., Mirkin, B. L., and Rebbaa, A. Control of multidrug resistance gene mdr1 and cancer resistance to chemotherapy by the longevity gene sirt1. Cancer Res, 65, 10183, 2005. 2. Howitz, K. T., Bitterman, K. J., Cohen, H. Y., Lamming, D. W., Lavu, S., Wood, J. G., Zipkin, R. E., Chung, P., Kisielewski, A., Zhang, L. L., Scherer, B., and Sinclair, D. A. Small molecule activators of sirtuins extend Saccharomyces cerevisiae lifespan. Nature, 425, 191, 2003. 3. Huffman, D. M., Grizzle, W. E., Bamman, M. M., Kim, J. S., Eltoum, I. A., Elgavish, A., and Nagy, T. R. SIRT1 is significantly elevated in mouse and human prostate cancer. Cancer Res, 67, 6612, 2007. 4. Nemoto, S., Fergusson, M. M., and Finkel, T. Nutrient availability regulates SIRT1 through a forkhead-dependent pathway. Science, 306, 2105, 2004. 5. Sauve, A. A., Moir, R. D., Schramm, V. L., and Willis, I. M. Chemical activation of Sir2-dependent silencing by relief of nicotinamide inhibition. Mol Cell, 17, 595, 2005. 6. Tardito, S., Uggeri, J., Bozzetti, C., Bianchi, M. G., Rotoli, B. M., Franchi-Gazzola, R., Gazzola, G. C., Gatti, R., and Bussolati, O. The inhibition of glutamine synthetase sensitizes human sarcoma cells to L-asparaginase. Cancer Chemother Pharmacol, 60, 751, 2007.

EORS 2008 · MADRID P-061

SOFT TISSUE SARCOMAS: EVALUATION OF A NEW ASPIRATION-CYTOLOGY-SYSTEM Mathias Glehr*, Paul Wretschitsch*, Thomas Kroneis**, Gerald Gruber*, Franz Quehenberger***, Andreas Leithner*, Reinhard Windhager* *Department of Orthopedic Surgery, **Institute of Histology ***Institute of medical Informatics, University Clinic Graz, Austria [email protected]

Discussion The needle systems with the air-valve led to a significantly higher cell amount in needle aspiration biopsy. According to the requirement of cytological diagnosis of soft tissue sarcomas more cell volume could be harvested, which is a well-defined benefit.

POSTER SESSIONS - FRIDAY

Materials and Methods In a blinded setting, 45 punctures from fresh pig thyroid glands were made and analyzed - 15 for each needle (conventional needle C-FNA , single-needle with air valve T-ONE and multi needle system with air valve T-THREE). The measurement was done according to the manufacturer´s recommendations for CASY (CASY® technology, Reutlingen). The aspirated cell material was evacuated into 10ml Casyton (cell-culture liquid, CASY® technology) and calculated with the CASY (CASY® technology) cell counter. Total cell amount and amount of vital cell was counted and recorded. Statistical analysis was performed using t-test (p
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17th Annual Meeting - European Orthopaedic Research Society

Reservados todos los derechos. All rights reserved Editor: E. Gómez-Barrena Co-editor: N. Bonsfills ISBN: 978-84-691-2464-2 D.L.: xxxxxxx Impreso e...

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