No description available.

Background: Modular mega-endoprosthesis systems are used to bridge very large bone defects and have become a widespread method in orthopaedic surgery for the treatment of tumours and revision arthroplasty. However, the indications for the use of modular mega-endoprostheses must be carefully considered. Implanting modular endoprostheses requires major, complication-prone surgery in which the limited salvage procedures should always be borne in mind. The management of periprosthetic infection is particularly difficult and beset with problems. Given this, the present study was designed to gauge the significance of periprosthetic infections in connection with modular mega-implants in the lower extremities among our own patients. Methods: Patients who had been fitted with modular endoprosthesis on a lower extremity at our department between September 1994 and December 2011 were examined retrospectively. A total of 101 patients with 114 modular prostheses were identified. Comprising 30 men (29.7 %) and 71 women (70.3 %), their average age at the time of surgery was 67 years (18–92 years). Results: The average follow-up period was 27 months (5 months and 2 weeks to 14 years and 11 months) and the drop-out rate was about 8.8 %. Altogether, there were 19 (17.7 %) endoprosthesis infections: 3 early infections and 16 late or delayed infections. The pathogen spectrum was dominated by coagulase-negative staphylococci (36 %) and Staphylococcus aureus (16 %), including 26 % multi-resistant pathogens. Reinfection occurred in 37 % of cases of infection. Tumours were followed by significantly fewer infections than the other indications. Infections were twice as likely to occur after previous surgery. Conclusion: In our findings modular endoprostheses (18 %) are much more susceptible to infection than primary endoprostheses (0.5–2,5 %). Infection is the most common complication alongside the dislocation of proximal femur endoprostheses. Consistent, radical surgery is essential – although even with an adequate treatment strategy, the recurrence rate is very high. Unfortunately, the functional results are frequently unsatisfactory, with amputation often being the last resort. Therefore, the indication for implantation must be carefully considered and discussed in great detail, especially in the case of multimorbid patients with previous joint infections.

Modulare Megaendoprothesensysteme dienen der Überbrückung sehr großer Knochendefekte und gehören mittlerweile in der Tumorbehandlung wie auch in der Revisionsendoprothetik zu etablierten Behandlungsmethoden in der Orthopädischen Chirurgie. Im ersten Teil dieser Ar-beit wird anhand der publizierten Literatur ein umfassender Überblick über wichtige Aspekte bei Megaendoprothesen gegeben (Geschichte, Indikationen, Charakteristika, Ergebnisse). Im zweiten Teil erfolgt im Rahmen der eigenen Erhebungen die Auswertung eines Patientengutes von 104 Patienten (114 Operationen), welche in den Jahren 1994–2011 in der Orthopädischen Universitätsklinik Leipzig mit dem modularen Megaendoprothesensystem MML (Modular-system München-Lübeck) an den unteren Extremitäten versorgt wurden. Die Ergebnisse wur-den anhand der Krankenakten ausgewertet und mithilfe eines Erhebungsbogens standardisiert erfasst. Bei den Indikationen dominierten Tumoren mit 39,5 %, gefolgt von Revisionsoperati-onen aufgrund von TEP-Lockerungen (33,3 %), periprothetischen Frakturen (21,9 %), pri-mären Frakturen (16,7 %), Pseudarthrosen (6,1 %) und Resektionen nach Infektionen (6,1 %). Die häufigste Lokalisation stellte der proximale Femurersatz dar (65,8 %). Insgesamt bewegte sich die Komplikationsrate mit 38,6 % im Bereich der Angaben der Literatur. Allerdings sind die Ergebnisse in der Literatur heterogen dokumentiert. Eine standardisierte Erfassung der Komplikationen würde zu einer deutlich besseren Vergleichbarkeit führen. In unseren Erhe-bungen war die Infektion die zweithäufigste Komplikation (12,3 %). Die Luxation nahm in unserem Patientengut mit 25,6 % den größten Stellenwert ein, war jedoch im Verlauf meist besser zu beherrschen als Infektionen. Des Weiteren kam es zu periprothetischen Frakturen (3,5 %), Lockerungen (3,5 %), einem Endoprothesenbruch (0,9 %) und einer deutlichen an-haltenden Bewegungsstörung (0,9 %). Bei der Versorgung mittels modularer Megaendopro-thesen handelt es sich um komplikationsträchtige Eingriffe. Gemessen an den oftmals schwie-rigen Ausgangssituationen bewegen sich jedoch die Komplikationsraten in einem akzeptablen Bereich. Insbesondere die Infektion der Megaendoprothese stellt eine schwerwiegende Kom-plikation dar und resultiert oft in komplizierten Verläufen, bis hin zum Verlust der Extremität. Somit muss der Infektprävention besonders große Beachtung geschenkt werden. Modulare Endoprothesen stellen eine wichtige und nützliche Therapieform dar, wobei die Indikation für einen solchen Eingriff angesichts der teils schwierigen Verläufe mit äußerster Sorgfalt gestellt werden sollte. Die Verwendung modularer Endoprothesensysteme sollte erfahrenen und spe-zialisierten Zentren vorbehalten sein.

Modulare Megaendoprothesensysteme dienen der Überbrückung sehr großer Knochendefekte und gehören mittlerweile in der Tumorbehandlung wie auch in der Revisionsendoprothetik zu etablierten Behandlungsmethoden in der Orthopädischen Chirurgie. Im ersten Teil dieser Ar-beit wird anhand der publizierten Literatur ein umfassender Überblick über wichtige Aspekte bei Megaendoprothesen gegeben (Geschichte, Indikationen, Charakteristika, Ergebnisse). Im zweiten Teil erfolgt im Rahmen der eigenen Erhebungen die Auswertung eines Patientengutes von 104 Patienten (114 Operationen), welche in den Jahren 1994–2011 in der Orthopädischen Universitätsklinik Leipzig mit dem modularen Megaendoprothesensystem MML (Modular-system München-Lübeck) an den unteren Extremitäten versorgt wurden. Die Ergebnisse wur-den anhand der Krankenakten ausgewertet und mithilfe eines Erhebungsbogens standardisiert erfasst. Bei den Indikationen dominierten Tumoren mit 39,5 %, gefolgt von Revisionsoperati-onen aufgrund von TEP-Lockerungen (33,3 %), periprothetischen Frakturen (21,9 %), pri-mären Frakturen (16,7 %), Pseudarthrosen (6,1 %) und Resektionen nach Infektionen (6,1 %). Die häufigste Lokalisation stellte der proximale Femurersatz dar (65,8 %). Insgesamt bewegte sich die Komplikationsrate mit 38,6 % im Bereich der Angaben der Literatur. Allerdings sind die Ergebnisse in der Literatur heterogen dokumentiert. Eine standardisierte Erfassung der Komplikationen würde zu einer deutlich besseren Vergleichbarkeit führen. In unseren Erhe-bungen war die Infektion die zweithäufigste Komplikation (12,3 %). Die Luxation nahm in unserem Patientengut mit 25,6 % den größten Stellenwert ein, war jedoch im Verlauf meist besser zu beherrschen als Infektionen. Des Weiteren kam es zu periprothetischen Frakturen (3,5 %), Lockerungen (3,5 %), einem Endoprothesenbruch (0,9 %) und einer deutlichen an-haltenden Bewegungsstörung (0,9 %). Bei der Versorgung mittels modularer Megaendopro-thesen handelt es sich um komplikationsträchtige Eingriffe. Gemessen an den oftmals schwie-rigen Ausgangssituationen bewegen sich jedoch die Komplikationsraten in einem akzeptablen Bereich. Insbesondere die Infektion der Megaendoprothese stellt eine schwerwiegende Kom-plikation dar und resultiert oft in komplizierten Verläufen, bis hin zum Verlust der Extremität. Somit muss der Infektprävention besonders große Beachtung geschenkt werden. Modulare Endoprothesen stellen eine wichtige und nützliche Therapieform dar, wobei die Indikation für einen solchen Eingriff angesichts der teils schwierigen Verläufe mit äußerster Sorgfalt gestellt werden sollte. Die Verwendung modularer Endoprothesensysteme sollte erfahrenen und spe-zialisierten Zentren vorbehalten sein.:Inhaltsverzeichnis ...................................................................................I Tabellenverzeichnis ................................................................................V Abbildungsverzeichnis ...........................................................................VI Abkürzungsverzeichnis .......................................................................VIII 1 Einführung und Aufgabenstellung........................................................ 1 2 Modulare Megaendoprothesen ........................................................... 3 2.1 Definition ......................................................................................... 3 2.2 Geschichte ....................................................................................... 5 2.3 Indikationen ............................................................................................................... 8 2.4 Modulare Megaendoprothesen – Charakteristik und Ergebnisse..... 9 2.4.1 Modulares Endoprothesensystem München-Lübeck™ (MML-System)....................................................................................... 10 2.4.2 KMFTR™/HMRS™ (Kotz-Modular-Femur-Tibia-Reconstruction-System/Howmedica-Modular-Reconstruction-System) ............................................................................................................. 12 2.4.3 MUTARS™ (Modular Universal Tumor and Revision System) ............................................................................................................. 16 2.4.4 Megasystem C™, Tumor- und Revisionssystem ............................................................................................................. 19 2.4.5 HSS(Hospital for Special Surgery)-modular linked system™/FINN™ ............................................................................................................. 20 2.4.6 STANMORE™ ............................................................................... 20 2.4.7 GUEPAR™-Endoprothese ............................................................ 21 2.4.8 Weitere Megaendoprothesensysteme ........................................ 21 3 Eigene Untersuchungen ................................................................... 23 3.1 Materialien und Methoden ............................................................. 23 3.2 Ergebnisse...................................................................................... 23 3.2.1 Charakteristika des Patientengutes ........................................... 23 3.2.1.1 Alters- und Geschlechtsverteilung ........................................... 23 3.2.1.2 Seitenverteilung ...................................................................... 24 3.2.1.3 Body-Mass-Index .................................................................. .. 24 3.2.1.4 Indikationen ............................................................................ 25 3.2.1.5 Tumoren als Indikation ............................................................ 25 3.2.1.6 Voroperationen ........................................................................ 27 3.2.1.7 Lokalisation der Endoprothese ................................................ 27 3.2.1.8 Charakteristika der mehrfach mit einer MML-Endoprothese versorgten Patienten ... ....................................................................... 28 3.2.2 Stationärer Aufenthalt bei MML-Endoprothesenimplantation ...... 29 3.2.2.1 OP-Dauer ................................................................................. 29 3.2.2.2 Muskel- und Sehnenrefixation, Trevira-Anbindungsschlauch ... 29 3.2.2.3 Intraoperative Komplikationen ................................................ 29 3.2.2.4 Stationäre Liegedauer ............................................................. 30 3.2.2.5 Postoperative Komplikationen während des stationären Aufenthaltes ........................................................................................ 30 3.2.2.6 Keimbefunde ............................................................................ 30 3.2.2.7 Implantatlage .......................................................................... 31 3.2.2.8 Reoperationen während des stationären Aufenthaltes ........... 31 3.2.2.9 Mobilisation .............................................................................. 32 3.2.3 Poststationärer Verlauf ............................................................... 32 3.2.3.1 Poststationäre Komplikationen ................................................ 32 3.2.3.2 Erneuter Eingriff poststationär ................................................ 34 3.2.4. Ausführliche Übersicht über die Komplikationen ........................ 35 3.2.4.1 Chirurgische Komplikationen und ihr Verlauf ............................ 35 3.2.4.2 Endoprothesenkomplikationen und ihr Verlauf ........................ 36 3.2.4.3 Geschlechtsspezifische Unterschiede bei den Komplikationen (stationär und poststationär zusammengefasst) ................................ 36 3.2.4.4 Altersunterschiede beim Auftreten von Komplikationen ........... 37 3.2.4.5 Einfluss des BMI auf die Komplikationen .................................. 38 3.2.4.6 Zusammenhänge zwischen der Indikation und Komplikationen ............................................................................................................. 38 3.2.4.7 Zusammenhänge zwischen Voroperationen und Komplikationen (stationär und poststationär zusammengefasst) ................................ 39 3.2.4.8 Komplikationen und Lokalisation der eingesetzten modularen Endoprothese ...................................................................................... 39 3.2.5 Letzter Untersuchungsbefund .................................................... 40 3.2.5.1 Zeitpunkt der letzten Untersuchung ........................................ 40 3.2.5.2 Schmerzen ............................................................................... 41 3.2.5.3 Beweglichkeit .......................................................................... 41 3.2.5.4 Gehfähigkeit ............................................................................ 42 3.2.5.5 Röntgenbefunde ...................................................................... 42 4 Diskussion ........................................................................................ 43 4.1 Diskussion der Datenerhebung ..................................................... 43 4.2 Diskussion der Ergebnisse ............................................................ 43 4.2.1 Allgemeine Angaben ................................................................... 43 4.2.2 Präoperative Angaben ................................................................ 44 4.2.3 Intraoperative Komplikationen ................................................... 45 4.2.4 Postoperative Komplikationen .................................................... 46 4.2.5 Poststationäre Komplikationen ................................................... 48 4.2.6 Zusammenhänge ........................................................................ 52 4.3 Resümee ........................................................................................ 54 5 Zusammenfassung ........................................................................... 56 6 Literaturverzeichnis .......................................................................... 59 7 Anlage.............................................................. ................................ 65 Erklärung über die eigenständige Abfassung der Arbeit ...................... 73 Lebenslauf und wissenschaftlicher Werdegang ................................... 74 Danksagung......................................................................................... 76

Background: Modular mega-endoprosthesis systems are used to bridge very large bone defects and have become a widespread method in orthopaedic surgery for the treatment of tumours and revision arthroplasty. However, the indications for the use of modular mega-endoprostheses must be carefully considered. Implanting modular endoprostheses requires major, complication-prone surgery in which the limited salvage procedures should always be borne in mind. The management of periprosthetic infection is particularly difficult and beset with problems. Given this, the present study was designed to gauge the significance of periprosthetic infections in connection with modular mega-implants in the lower extremities among our own patients. Methods: Patients who had been fitted with modular endoprosthesis on a lower extremity at our department between September 1994 and December 2011 were examined retrospectively. A total of 101 patients with 114 modular prostheses were identified. Comprising 30 men (29.7 %) and 71 women (70.3 %), their average age at the time of surgery was 67 years (18–92 years). Results: The average follow-up period was 27 months (5 months and 2 weeks to 14 years and 11 months) and the drop-out rate was about 8.8 %. Altogether, there were 19 (17.7 %) endoprosthesis infections: 3 early infections and 16 late or delayed infections. The pathogen spectrum was dominated by coagulase-negative staphylococci (36 %) and Staphylococcus aureus (16 %), including 26 % multi-resistant pathogens. Reinfection occurred in 37 % of cases of infection. Tumours were followed by significantly fewer infections than the other indications. Infections were twice as likely to occur after previous surgery. Conclusion: In our findings modular endoprostheses (18 %) are much more susceptible to infection than primary endoprostheses (0.5–2,5 %). Infection is the most common complication alongside the dislocation of proximal femur endoprostheses. Consistent, radical surgery is essential – although even with an adequate treatment strategy, the recurrence rate is very high. Unfortunately, the functional results are frequently unsatisfactory, with amputation often being the last resort. Therefore, the indication for implantation must be carefully considered and discussed in great detail, especially in the case of multimorbid patients with previous joint infections.

<p>U prvom poglavlju je ukazano na potrebu ugradnje implantata u cilju ponovnog<br />uspostavljanja normalnog funkcionisanja lokomotornog sistema čoveka. Na osnovu<br />analize broja i strukture ugrađenih endoproteza zgloba kuka za 2014. i 2015. godinu na<br />IOHB &bdquo;Banjica&ldquo;, Beograd, i Kliničkom centru Vojvodine Novi Sad, Klinika za ortopediju<br />i traumatologiju, zaključuje se da ovi pokazatelji ukazuju na sličnost i uporedivost, sa<br />podacima iz SAD, u odnosu na broj stanovnika.<br />Drugo poglavlje, u uvodnom delu, sadrži sistematizaciju endoproteza zgloba kuka u skladu sa standardom ISO 7216. Nakon toga, dat je prikaz dosadašnjih rezultata primene tumorskih modularnih endoproteza. Pažnja je poklonjena opisu i varijantnosti konstrukcionih elemenata modularnih endoproteza zgloba kuka, kao i analizi izvedenih konstrukcionih rešenja. Prikaz dosadašnjih istraživanja je upotpunjen analizom patentnih rešenja modularnih endoproteza zgloba kuka. Na kraju, polazeći od prethodno sumiranih saznanja, i iskustva u razvoju protetičkih pomagala je definisan cilj istraživanja, osnovne hipoteze, materijal i metode.<br />Treće poglavnje sadrži kratak prikaz koštanih tumora i istorijat tumorske<br />endoproteze. Ukazuje se na komplikacije nakon ugradnje kao i na kriterijume za ugradnju<br />tumorske endoproteze. Primarni i sekundarni tumori, neuspela aloartroplastika,<br />prelomi preko ili ispod trohantera, patološki prelom, često prouzrukuju totalno<br />razaranje gornjeg dela butne kosti, i ovi uslovi predstavljaju indikaciju za zamenu<br />gornjeg dela butne kosti tumorskom endoprotezom. Cilj ugradnje tumorske endoproteze<br />zgloba kuka je da se spase ekstremitet, očuva estetika i obezbedi zadovoljavajuća<br />funkcionalnost i neutrališe prisustvo bola. Ne može se očekivati da endoprotetski<br />sistem ima neograničen vek. Za pojedine delove koji su izloženi intenzivnom habanju u<br />toku eksplatacije potrebno je obezbediti mogućnost jednostavne zamene uz minimalan<br />hirurški zahvat.</p><p>Sa biomehaničkog aspekta projektovanja, sistem fiksacije i konfiguracija tela<br />endoproteze mora biti takav da minimizira naponsko stanje ili obezbedi povoljniju<br />raspodelu napona.<br />Četvrto poglavlje je posvećeno definisanju strukture i dimenzija komponenti sistema<br />tumorske modularne endoproteze zgloba kuka. Ukazuje se na postupak i uticajne faktore<br />na proces projektovanja, kao i na pouzdanost projektovanog rešenja. Posebna pažnja je<br />posvećena dimenzionisanju donje komponente endoproteze sa stanovišta pojave<br />koncentracije napona, kao i elementima za vezu i stezanje komponenti u jedinstven<br />mehanički sistem. Dimenzije pojedinih komponenti su definisane na bazi statističkih<br />razultata do sada ugrađenih tumorskih monolitnih endoproteza na IOHB &bdquo;Banjica&ldquo;<br />Beograd.<br />U okviru petog poglavlja, prikazani su rezultati računarske analize statičkog<br />ponašanja tela monolitne, odnosno donje komponente tumorske modularne endoproteze<br />zgloba kuka. Prvo su prikazana preliminarna ipsitivanja pri statičkom opterećenju, i to<br />računarsko simuliranje eksperimentalnih ispitivanja i sama eksperimentalna<br />ispitivanja za obe vrste tumorskih endoproteza. Na bazi ovih rezultata izvršeno je<br />remodelovanje donje komponente i umesto radijusa prelaza između kragne i tela - mesto<br />maksimalnih napona u implantatu, definisan je optimalni bionički profil prelaza.<br />Nakon izrade donjih komponenti od različitih materijala i različitih profila prelaza<br />realizovana su završna ispitivanja komponenti tumorske modularne endoproteze pri<br />statičkom opterećenju. I kod završnog ispitivanja prvo je izvršeno računarsko<br />modelovanje a nakon toga i eksperimentalno ispitivanje. Pri eksperimentalnom<br />ispitivanju meren je napon u jedanaest mernih tačaka po profilu prelaza između kragne<br />i tela. Dobijeni rezultati su poređeni sa računarskim modeliranjem i konstatovano je<br />zadovoljavajuće poklapanje raspodele i maksimalnih napona po profilu prelaza između<br />kragne i tela endoproteze. Za slučaj delovanja dinamičkog opterećenja izvršena su<br />eksperimentalna laboratorijska ispitivanja. Pri ovom ispitivanju definisane su<br />sledeće promenljive: 1. vrsta endoproteze: monolitna i modularna, 2. materijal:<br />superlegure čelika 316LVM i titanijuma Ti6Al4V, 3. oblik prelaza: sa radijusom i<br />optimizirani prelaz. Cilj ovog ispitivanja ja da se utvrdi broj ciklusa koji će dovesti<br />do početka razlabavljenja tela endoproteze pri maksimalnim uslovima opterećenja, tj.<br />da li navedene promenljive daju statistički značajnu razliku u broju ciklusa do pojave<br />razlabavljenja, kasne mehaničke komplikacije koja prethodi lomu usled zamora<br />materijala, ili zahteva reviziju. Pri ovom ispitivanju fizički prototipovi<br />endoproteza su, izloženi jednosmerno promenljivoj sili, Fmax=2500N, amplitude 2000N i<br />frekvencije 15-20 Hz. Vršena je vizuelena kontrola pojave radiolucentne linije između<br />tela endoproteze i koštanog cementa, odnosno kosti, kao pouzdani znak početka<br />razlabavljenja, kao i Rtg snimaka od strane ortopedskih hirurga nakon svakih 500.000<br />ciklusa, za sve uzorke. Analiza rezultata nakon ispitivanja pri dinamičkom opterećenju<br />uzoraka izrađenih od superlegure čelika 316LVM i uzoraka izrađenih od superlegure<br />titanijuma Ti6Al4V ukazuje na visoku pouzdanost odnosno nizak nivo rizika da može doći<br />do razlabavljenja i do pojave loma usled zamora materijala. Profil prelaza sa velikog<br />na mali prečnik za slučaj radijusa i optimizirani bionički profil nisu pokazali<br />značajnu statističku razliku kod ispitivanja pri dinamičkom opterećenju. Na kraju je<br />pojava razlabavlja utvrđivana i inženjerskom metodom. Nakon ispitivanja dinamičkim<br />opterećenjem fizički prototipovi endoproteza su ponovo izloženi statičkom<br />opterećenju i konstatovano je da nema značajnijih promena u raspodeli i vrednostima<br />maksimalnih napona, što ukazuje da nije došlo da pojave razlabavljenja.<br />Kroz šesto poglavlje dat je kratak opis biokompatabilnih materijala, legura čelika<br />316LVM, kobalta CoCrMo, titanijuma Ti6A14V &bdquo;eli&ldquo;, poroznih i keramičkih materijala,<br />materijala od plastične mase, kompozita i bioreseptivih materijala. Nakon toga su<br />prikazani rezultati ispitivanja biokompatabilnosti materijala koji su primenjeni za<br />izradu elemenata modularnog sistema endoproteza. Rezultati ispitivanja su pokazali<br />da materijali i tehnološki proces proizvodnje zadovoljavaju sa stanovišta<br />biokompatabilnosti.<br />Sedmo poglavlje sadrži zaključke, na osnovu rezultata pojedinih poglavlja i<br />izvedenih istraživanja. Nakon toga dati su pravci budućih istraživanja.<br />Osmo poglavlje sadrži pregled korišćene literature, koju čini 68 literaturnih<br />naslova od kojih je najveći broj citiran u radu.</p> / <p>In the first chapter, the need of implant insertion was apostrophed, with the purpose to achieve<br />normal functioning of human locomotory system. On the base of analysis of the number and the<br />structure of implanted hip endoprosthesis during the years 2014. and 2015. at IOHB &ldquo;Banjica&rdquo;,<br />Belgrade, and at Clinical center of Vojvodina, Novi Sad, Clinic of orthopedy and traumatology, it<br />was concluded that the data, related to the number of citizens, show to be similar and<br />comparable with those from the USA.<br />In the second chapter, in the preface section, the systematization of hip endoprosthesis<br />according to the norm ISO 7216 was presented. After that, the results of historical application of<br />modular tumor endoprosthesis was presented. The attention was paid to the description and<br />structure element variants of modular hip endoprosthesis, and also to the analyses of existing<br />prosthesis constructions. The results of up to now conducted research were additionally enriched<br />with patented variants of modular hip endoprosthesis. At the end, based on previously summed<br />knowledge and experiences in the field of development of prosthetic aids, the goal of the<br />research was determined, so as basic hypothesis, materials and methods.<br />Third chapter comprises short description of bone tumors and historic development of tumor<br />endoprosthesis. The complications after implantation were discussed and also the criteria for the<br />implantation of tumor prosthesis. Primary and secondary tumors, failed arthroplasty, fractures<br />across or beneath trochanter and pathologic fractures are frequent causes of total destruction of<br />the upper portion of the femur and require the replacement of it with tumor prosthesis. The aim of<br />hip tumor prosthesis implantation is to save the limb, to preserve esthetic, to provide satisfactory<br />functionality and to neutralize the pain. It is not possible to expect that endoprosthetic system<br />achieves en infinitely long service life. For some of the components, which are during the service<br />exposed to intensive wear and tear, it is necessary to provide the possibility of simple<br />replacement, with the need for a minimal surgical intervention. From the aspect of biomechanical</p><p>design, the fixation system and body configuration of an endoprosthesis must be such, as to<br />minimize stress level and to provide for a convenient stress distribution.<br />The fourth chapter is dedicated to the definition of the structure and components&rsquo; dimensions<br />for a system of modular hip endoprosthesis. It was dealt with the procedure and with the<br />influencefull factors on a design process and also with the reliability of a designed solution.<br />Special care was devoted to the dimensioning of the upper portion of endoprosthesis from the<br />standpoint of stress concentration and to the elements for the connection and joining the<br />elements in a compact mechanical system. The measures of certain components were defined<br />on the base of statistic analysis of up to now implanted monolithic tumor endoprosthesis at IOHB<br />&ldquo;Banjica&rdquo;, Belgrade.<br />Within fifth chapter, the results of computer analysis of static behavior of the body of monolithic<br />component (lower section) of modular tumor hip endoprosthesis was presented. As the first, the<br />results of preliminary examinations with static load were presented, both the computer simulation<br />of experimental testing and the results of real experimental testing, for both types of tumor<br />endoprosthesis. On the base of these results, the remodeling of the lower component was<br />undertaken so that instead of the connection of a collar and the prosthesis body with the shape<br />of a constant radius (the spot with the maximum stress in the prosthesis), an optimal bionically<br />shaped connection was defined. After the production of lower prosthesis components from<br />different materials and with the different shapes, the final examinations of the components of<br />modular tumor hip endoprosthesis under static load were performed. For the final examinations,<br />in the first step also the computer modeling was performed, and consequently experimental<br />testing. When performing experimental testing, the stress level was determined at eleven<br />measuring spots, on the prosthesis section between the collar and the body. Acquired results<br />were compared to the results acquired through computer modeling and an adequate overlapping<br />of stress distribution and maximum stress in the region between the collar and the prosthesis<br />body was detected. For the case of dynamic load, the laboratory experimental examinations<br />were performed. For these examinations the following variables were determined: 1.<br />endoprosthesis type: monolithic and modular, 2. material: steel superalloy 316LVM and of<br />titanium Ti6Al4V, 3. shape of a connection between the collar and prosthesis body: with constant<br />radius and with the optimized shape. The aim of this examination was to determine the number<br />of cycles which would lead to the beginning of the loosening of the prosthesis body under the<br />conditions of maximum load or, with other words, it was to be determined if mentioned variables<br />provide for significant statistic difference in cycle numbers to the point of prosthesis loosening, to<br />the consequent mechanic complication predicting material fatigue failure or demanding surgical<br />revision. When conducting the examination, physical models of endoprosthesis were exposed to<br />the influence of unidirectionally changing force with the parameters of Fmax = 2500N, Fampl =<br />2000N, frequency 15-20 Hz. After every 500.000 load cycles, for all the samples, the appearance<br />of a radiolucent line between the prosthesis body and bone cement and the bone itself, as the<br />reliable sign of the loosening onset, was visually checked on Rtg shots by orthopedic surgeons.<br />The analysis of the results for behavior under dynamic load, for the samples from steel<br />superalloy 316LVM and from titanium Ti6Al4V shows that they posses high reliability and that<br />there is a low probability that the loosening and the fatigue failure will occur. When examined<br />under dynamic load, prosthesis section with the change from small diameter to large diameter,<br />for the case with constant radius and for the case with optimized bionic profile, have not shown<br />statistically significant difference. At the end, the loosening appearance was examined under the<br />application of engineering methods. After exposing the prosthesis to the dynamic load, physical<br />prototypes of prosthesis were anew exposed to static load and it was confirmed that there is no<br />significant change in the distribution and the level of maximum stress, what was the proof that no<br />loosening has occurred.<br />Within the sixth chapter, the short description of biocompatible materials was given, of steel<br />alloy 316LVM, cobalt CoCrMo, titanium Ti6Al4V &ldquo;eli&rdquo;, of porous and ceramic materials, plastic<br />materials, composites and bioreceptive materials. Subsequently, the results of biocompatibility<br />examination of materials which were applied for the production of the elements of modular<br />endoprosthesis system were presented. The acquired results have proved that the materials and<br />the production process are satisfactory from the standpoint of biocompatibility.<br />Seventh chapter comprises the conclusions, based on specific previous chapters and the<br />research results. After that, the suggestions for the future research were outlined.<br />Eight chapter comprises an overview of used literature, with 68 titles, most of which were cited<br />in this work.</p>

Einleitung 2015 belegte die Implantation einer Endoprothese am Hüftgelenk mit 219.325 Operationen Platz 8 der 50 häufigsten Operationen der vollstationären Patienten in Krankenhäusern (DRG-Statistik 2015). Bei diesen Eingriffen kommt eine Vielzahl von verschiedenen Prothesenmodellen zum Einsatz (Kirschner 2005). Aktuell geht der Trend in Richtung zementfreie Verankerung, Verkleinerung der Implantate und den Erhalt von möglichst viel Knochensubstanz (Jerosch 2013). So werden in den letzten Jahren immer häufiger Kurzschaftendoprothesen implantiert (Jerosch 2013). Sie stellen ein knochensparendes System dar und erlauben gleichzeitig verschiedene Gleitpaarungen (Jerosch 2013). Allerdings liegen für die meisten Kurzschaftendoprothesentypen noch keine Langzeittestergebnisse vor (Jerosch 2011), so dass das Langzeitverhalten dieser Prothesen nicht vorhergesagt werden kann. Speziell bei Kurzschaftendoprothesen ist der Einfluss der verkürzten Schaftlänge auf das Einwachsverhalten und die Lebensdauer des Implantats noch nicht ausreichend geklärt. Am Lehrstuhl für Konstruktionslehre und CAD der Universität Bayreuth finden deshalb Untersuchungen zur computergestützten Analyse von Kurzschaftendoprothesen statt. Ziel hierbei ist es, durch eine Variation der Schaftlänge eine Prothesenform mit optimalen Spannungsverläufen und einer verbesserten Krafteinleitung in den Knochen zu entwickeln.

No description available.

L’anévrisme de l’aorte abdominale (AAA) est une pathologie devant être traitée par un acte chirurgical afin d’éviter une rupture, mortelle dans la majorité des cas. Son traitement par chirurgie endovasculaire (EVAR) a pour objectif d’éviter toute opération trop lourde et invasive en déposant une endoprothèse au sein de l’AAA par voie artérielle, à laquelle le chirurgien accède via une simple incision de l’artère fémorale. Les diffeìrents retours cliniques montrent globalement que les probleÌmes post-opeìratoires observeìs - migration, plicature, endofuite, rupture – sont intimement lieìs aÌ la conception des endoprotheÌses actuelles, reìaliseìes par l’assemblage d’un corps textile avec un exosquelette sutureì sur ce dernier. Ces dernières preìsentent aujourd’hui un comportement mécanique treÌs heìteìrogeÌne, et éloigné de celui de l’aorte native. Ces problèmes post-opératoires conduisent très souvent à une nécessité de ré-opération des patients, ce qui réduit à long terme les bénéfices de la chirurgie endovasculaire.Les sollicitations in-vivo auxquelles est soumise l’endoprothèse sont diverses. La sollicitation principale de gonflement engendrée par la pression du flux sanguin, s’accompagne d’une compression exercée par les organes environnants, mais également de la flexion due aux mouvements du patient et aux géométries tortueuses des anévrismes, etc. Le comportement mécanique de l’endoprothèse doit être biomimétique dans la mesure du possible afin de se calquer sur la portion artérielle d’origine, i.e. limiter des discontinuités mécaniques aux collets, responsables d’hyperplasie intimale.Dans ce contexte, cette thèse a pour objectif de contribuer au développement et à l’optimisation d’endoprothèses vasculaires, issues d’une technologie de fabrication innovante permettant d’insérer une trame hélicoïdale métallique en NiTi au sein d’un corps textile PET tricoté par maille jetée. Cette technologie permet de réaliser des structures textiles homogènes sans exo-squelette. Dans le but d’optimiser les structures produites, différents essais expérimentaux ont été mis en place, couplés à des techniques d’imagerie 2D ou 3D – micro-tomographie RX synchrotron et de laboratoire – afin de caractériser leur comportement mécanique ainsi que leur comportement au fluide (perméabilité). Les résultats de ces différents essais sont comparés lorsque cela est possible à des résultats expérimentaux ou numériques de la littérature sur l’aorte saine, ainsi qu’à des données concernant des produits du marché. Le but final de ces travaux est d’accéder au développement d’une structure endoprothétique type, dont le comportement est proche de celui de l’aorte abdominale native et permettant de limiter les problèmes post-opératoires observés aujourd’hui. / Abdominal aortic aneurysm (AAA) is a pathology that must be repaired by a surgical procedure to avoid a rupture, lethal in most of the cases. Endovascular aneurysm repair (EVAR) is a non-invasive procedure, allowing the deployment of a stent-graft inside the aneurysmal sac. Nevertheless, clinical feedback currently available for stent-grafts show that many complications after surgery – migrations, thrombosis, endoleaks, rupture – are closely linked to the mechanical behaviour of the stent-grafts, which is heterogeneous and very far from the one of the aorta. This behaviour is induced by the design of current stent-grafts, made by assembling a textile body with an exoskeleton sutured on the latter. These post-operative problems frequently lead to a second operation of the patient, which drastically reduces the benefits of endovascular surgery.In-vivo, stent-grafts are submitted to various loadings: inflation induced by the blood pressure, compression due to surrounding organs, but also bending due to the patient motion or the aorta tortuosity, etc. As far as possible, the mechanical behaviour of stent-grafts must also be as closed as possible to the original aorta, to avoid mechanical discontinuities that may be responsible for intimal hyperplasia.In this context, the principal purpose of this thesis is to contribute to the development and the optimization of vascular endoprostheses, resulting from an innovative manufacturing technology whose target is to insert a helical metallic wire in NiTi within a knitted PET textile body. This technology allows to build homogeneous textile tubes without any exo-skeleton. In order to optimize these structures, various experimental tests coupled with 2D or 3D imaging techniques – Synchrotron and laboratory X-ray micro-tomography – have been developed to characterize the mechanical behavior as well as permeability of these tubes. The results of these different tests are compared to experimental or numerical results of the literature regarding the native aortic tissue, as well as data concerning market products. The ultimate goal of this work is to provide new stent-grafts whose behavior is close to the native abdominal aorta, and which limit current post-operative problems.

Aneurismas são dilatações permanentes iguais ou superiores a 50% do diâmetro original de uma artéria ou do diâmetro proximal da mesma, de acordo com consenso publicado pela Sociedade de Cirurgia Vascular da América do Norte e Sociedade Internacional de Cirurgia Cardiovascular em 1991 (Vliet e Boll, 1997). Aneurisma de aorta é uma doença vascular que afeta mais de 5% da população masculina com mais de 55 anos de idade (How et al., 2005). Desde 1991 um novo método vem sendo utilizado como tratamento deste quadro clínico. Este novo método é considerado menos invasivo e com menor comorbidade, uma vez que se trata da instalação de uma endoprótese por meio de catéter através da artéria femoral. Neste trabalho, será verificado o escoamento através de três aneurismas de aorta abdominal (AAA) e das endopróteses indicadas para o tratamento de cada um dos aneurismas. Foram feitas simulações computacionais afim de se obter as pressões, as velocidades do escoamento sanguíneo e as tensões de cisalhamento na parede das geometrias, usando pulsos de pressão e velocidade fisiológico de um individuo adulto, normotenso, em repouso. No modelo de escoamento simulado, foi adotado o sangue como fluido Newtoniano, incompressível e homogêneo. Foi usado um modelo de turbulência K-, com interpolador upwind de 2ª ordem e tratamento de parede nas geometrias, para que se fosse possível obter resultados satisfatórios (das camadas próximas à parede, e de todos os vórtices). Os resultados obtidos no trabalho foram satisfatórios, uma vez que eles expressaram de forma realista o comportamento do escoamento sanguíneo pelos aneurismas e endopróteses. Foi possível justificar com esse trabalho a instalação de endopróteses em pacientes, quando necessário, com o objetivo de diminuir significativamente a degradação do vaso, causando a ruptura do aneurisma. / Aneurisms are permanently dilatation higher than 50% of the original diameter of an artery or of the proximal diameter of them, according to the published consensus of the Vascular Surgery Society of North America and International Society of Cardiovascular Surgery on 1991 (Vliet and Boll, 1997). Aortas Aneurism is a vascular disease that affects more than 5% of the male population, with more than 55 years old (How et al, 2005). Since 1991, a new method is used in the treatment of these diseases. This new method is less invasive and has less comorbidity. This method is provided by the installation of an endoprosthesis through the catheter through the femoral artery. In this work, the flow will be verified through three abdominal aortic aneurysms (AAA) and the endoprosthesis indicated for the treatment of each of the aneurysms. Computational simulations were made in order to obtain the pressures, velocities of the blood flow and the shear stresses on the wall of geometries, using a pulse pressure and velocity of an individual physiological adult normotensive at rest. For the fluid simulations, it was adopted the blood as Newtonian fluid, incompressible and homogeneous. In simulations, it was used a K- model of turbulence, with 2nd order upwind interpolator and wall geometry treatment in order to obtain satisfied results (on the layers near the walls, and all the vortices). The results obtained in this work were satisfied, once they expressed the realistic behavior of the blood flow through the aneurysm and the endoprosthesis. It was possible to justify with this work the installation of an endoprosthesis inside patients, when it is necessary, in order to decrease significantly the vessels degradation, causing the aneurysm rupture.