Ziel der vorliegenden Arbeit war es, retrospektiv die Ergebnisse der bei medialer Schenkelhalsfraktur mittels 3-fach Verschraubung osteosynthetisch versorgten Patienten zu ermitteln und die Ergebnisse im aktuellen Kontext im Vergleich zu den Ergebnissen anderer Studien darzustellen. Aufgrund der zunehmenden sozioökonomischen Bedeutung der Therapie der medialen Schenkelhalsfraktur ist es im Prozess des Findens einer optimalen Versorgung der betroffenen Patienten erforderlich, die aktuell angewandten Therapieverfahren klinischen Studien zu unterziehen, um für künftige Patienten eine fundierte Entscheidung für das entsprechende Therapieverfahren treffen zu können. Die retrospektive Arbeit bezog sich auf 86 Patienten, welche auf Grund einer medialen Schenkelhalsfraktur durch 3-fach Verschraubung versorgt worden sind. Es wurden entscheidende präoperative Daten, wie der präoperative Zustand des Patienten, deren Alter, Geschlecht, Frakturklassifikation und die Zeit zwischen Aufnahme in der Unfallambulanz und Operation erfasst. Zusätzlich wurden postoperative Daten zu Komplikationen erhoben und Langzeitergebnisse im Rahmen einer klinischen Nachuntersuchung erfasst. Bei einem Frauenanteil von 63% hatte das Patientenkollektiv ein Durchschnittsalter von 73 Jahren. Zum Zeitpunkt der Nachuntersuchung waren 38,4% der Patienten verstorben. Insgesamt kam es bei 10,5% der Patienten zu einer Redislokation, wobei der Anteil der Redislokationen bei den Patienten mit einer dislozierten Fraktur 26% und bei den Patienten mit einer nicht dislozierten Fraktur 3,4% betrug. Im Patientenkollektiv entwickelten 4,7% der Patienten eine Pseudarthrose und bei 5,8% der Patienten konnte die Entstehung einer Hüftkopfnekrose beobachtet werden. Bei den 24 nachuntersuchten Patienten konnte ein durchschnittlicher Harris Hip Score von 89,5 Punkten ermittelt werden.

Die vorliegende Dissertation beschäftigt sich mit der Untersuchung des Ermüdungsverhaltens einer neu entwickelten Ti-40(wt%)Nb Legierung für die Anwendung als Implantatwerkstoff aus der Materialklasse der β-Titanlegierungen. Darüber hinaus werden auch vergleichende Ermüdungsuntersuchungen zu den Werkstoffen Ti-45(wt%)Nb als weitere binäre β-Titanlegierung sowie an α-Titan als klassischem Referenzwerkstoff im industriellen Einsatz durchgeführt. Ziel ist es, grundlegende Erkenntnisse zu den zyklischen Verformungsmechanismen binärer Ti-Nb Legierungen in Abhängigkeit ihres Werkstoffzustandes und damit Ihrer Mikrostruktur zu erhalten. Im Vergleich mit anderen Implantatwerkstoffen soll daraus eine mögliche Eignung für den Einsatz als nicht resorbierbares Osteosynthesematerial abgeleitet werden. Als übergeordnetes Ziel wird hierbei eine Minimierung des Elastizitätsmodules bei gleichbleibend hohen statischen und zyklischen Festigkeiten angestrebt, um einerseits schnellere Heilungserfolge zu erzielen als auch eine möglichst dauerhafte Implantatzuverlässigkeit zu gewährleisten. Für diesen Zweck wurden umfangreiche Ermüdungsprüfungen an Werkstoffproben und Osteosyntheseplatten in Abhängigkeit von Werkstoff, Mikrostruktur, Oberfläche, Umgebung und Geometrie durchgeführt. Mit Hilfe von strukturanalytischen Verfahren vor und nach der Werkstoffermüdung wurden diese begleitend detailliert charakterisiert. Insbesondere die Ergebnisse zum Einfluss des Werkstoffzustandes von Ti-40Nb erbrachten hierbei direkte Unterschiede und eine um ca. 30 % höhere Schwingfestigkeit im ausgelagerten Zustand aufgrund von vorliegenden isothermen Ausscheidungen der ω-Phase. Zurückgeführt wurde diese Erhöhung zum einen auf einen dominanten Effekt der Ausscheidungshärtung sowie die Unterdrückung von einer in binären Ti-Nb Legierungen möglichen Phasenumwandlung während der zyklischen Belastung. Stattdessen wurden nur im Ermüdungsrissbereich den Gleitbändern ähnliche Deformationsbänder (DB’s) beobachtet, die als ω-verarmte Versetzungskanäle die plastische Verformung tragen, während im rekristallisierten Zustand eine nahezu komplette Transformation in die martensitische α‘‘-Phase infolge der Ermüdung generiert wird. Der Einfluss der Oberfläche wird hierbei als signifikant herausgestellt, da vor allem Kerbeffekte die erreichbaren Schwingfestigkeiten der untersuchten Ti-Nb Legierungen massiv beeinflussen und zum vorzeitigen Versagen führen. Ein überlagerter Geometrieeinfluss, wie im Fall untersuchter Osteosyntheseplatten, hat einen zusätzlichen dominanten negativen Effekt auf das Ermüdungsverhalten. Ein negativer Einfluss eines korrosiven Umgebungsmediums am Beispiel einer Lösung aus simulierter Körperflüssigkeit (SBF) kann hingegen nicht festgestellt werden, was auf die exzellenten Selbstpassivierungseigenschaften von β-Titanlegierungen auf Ti-Nb Basis zurückgeführt wird. Insgesamt ergibt sich auf Grundlage der Ergebnisse dieser Arbeit eine nur bedingte Einsatzfähigkeit als Werkstoff für die Osteosynthese. Vorteile, wie der sehr geringe Elastizitätsmodul und die exzellente Widerstandfähigkeit gegen Korrosionsermüdung stehen einer allgemein nur ausreichenden Schwingfestigkeit sowie hoher Empfindlichkeit für Kerbeffekte jeglicher Art gegenüber. Eine effiziente Ausnutzung der Auslagerungseffekte sowie eine Oberflächennachbehandlung auf Basis von Druckeigenspannungen bieten jedoch weiteres hohes Potential für das Ermüdungsverhalten binärer Ti-Nb Legierungen. / Present thesis investigates the fatigue behavior of a newly developed Ti-40(wt%)Nb alloy from the material class of β-titanium alloys for application as implant material. Furthermore it investigates the fatigue behavior of the binary β-titanium alloy Ti-45(wt%)Nb and α-titanium as standard material already in industrial application for reference. Main focus are the detection of cyclic deformation mechanisms in dependence of material condition and the underlying microstructure. In comparison with other implant alloys, suitability of the new Ti-40Nb alloy as osteosynthesis material shall be evaluated. The overall aim is thereby the minimization of the Young’s modulus with simultaneously high values of static and cyclic strength for better healing chances and long term implant reliability. For this objective, comprehensive fatigue testing on material samples as well as osteosyn-thesis plates was carried out in dependence of material, microstructure, surface, environ-ment and sample geometry. Detailed structural analyses were additionally carried out be-fore and after fatigue testing. Compared with the recrystallized condition of the Ti-40Nb al-loy, fatigue results of the aged condition with present isothermal ω-precipitates in the β-matrix show a 30% higher fatigue strength. Uncovered reasons for this behavior are a domi-nant effect of precipitation hardening as well as the complete suppression of for β-titanium alloy commonly observed phase transformations during fatigue. Whereas the recrystallized condition of the Ti-40Nb alloy is characterized by significant martensitic α’’-phase formation and occasional mechanical twin development during fatigue, the aged condition shows none of these characteristics. Instead deformation bands (DB’s), similar to commonly overserved slip bands during fatigue, are detected in the immediate area of the fatigue crack. These localized DB’s carry all of the plastic deformation in the aged condition of the Ti-40Nb alloy as ω-depleted dislocation channels. Furthermore, the influence of the surface condition regarding the fatigue properties is sig-nificant. The reason are notch effects leading to localized stress concentration and early fa-tigue failure. Tests on the osteosynthesis plates show in addition a superimposed effect of the geometry, which leads to an even more decreased fatigue strength of Ti-40Nb and the reference α-titanium. A negative influence of corrosion fatigue in simulated body fluid (SBF) is on the contrary not detected, which is caused by the excellent self-passivating properties of β-titanium alloys on the basis of Ti-Nb. An overall evaluation of the material leads to an only limited suggestion as osteosynthesis material. Advantages are the very low Young’s modulus and the excellent corrosion fatigue resistance. Disadvantages are the only insufficient fatigue strength compared to other standard implant materials and the high susceptibility for notch effects leading to a rapid decrease of fatigue strength. Nevertheless, an efficient use of the positive effects of the aged condition as well as a surface post-treatment to induce positive residual compression stresses provide high potential for Ti-40Nb or the binary Ti-Nb alloys in general.

Bei der internen, extramedullären Osteosynthese des distalen Femurs, auf die sich diese Arbeit fokussiert, haben sich in den letzten Jahren interessante Entwicklungen vollzogen. Ausgehend von unzufriedenstellenden Komplikationsraten wurden neue Wege in der Versorgung dieser schwierigen Frakturen gesucht. Osteosynthesematerialien, Repositionstechniken, die Technik der Implantatplatzierung und die Implantate selbst, bei denen die Entwicklung zu winkelstabilen Systemen gegangen ist, haben sich grundlegend geändert. Die vorliegende Arbeit analysiert in einer retrospektiven Studie distale Femurfrakturen, die zwischen dem 1.1.1995 und 31.9.2000 entweder mit einem Fixateur interne (LISS) oder mit der konventionellen Plattenosteosynthese versorgt wurden. In die Studie konnten 51 Patienten mit 54 distalen Femurfrakturen eingeschlossen werden. Die Infektionsrate war in der LISS-Gruppe (0% versus 11,1%) nichtsignifikant geringer, die Rate der verzögerten Frakturheilungen war nichtsignifikant höher. Die einzige verzögerte Frakturheilung (LISS-Gruppe), die einer sekundären chirurgischen Intervention bedurfte, wurde bei einer Patientin mit einem großen Knochendefekt gesehen, der ohne primäre Spongiosaplastik therapiert worden war. Pseudarthrosen traten in beiden Gruppen nicht auf. Die Rate des Materialversagens unterschied sich nicht signifikant. Beim LISS kam es nicht, wie bei den konventionellen Implantaten zu sekundären Repositionsverlusten, es wurden aber im Anfang der klinischen Einführung proximale Schraubenausrisse aufgrund einer Fehlplatzierung gesehen. Es konnte gezeigt werden, dass es durch die Verwendung des LISS und die indirekten Repositionstechniken zu keiner Zunahme der Achsfehlstellungen oder der Operationszeit kam. Die funktionellen Einzelergebnisse und die Punktzahl der erhobenen Scores (Neer-Score und Lysholm-Score) unterschieden sich nicht signifikant. / Internal, extramedullary osteosynthesis of distal femoral fractures which are focussed on in this study has been influenced by interesting developments in recent years. Driven by unsatisfying complication rates new fracture treatments have been looked for. Osteosynthesis materials, reduction techniques, techniques of implant placement and implants themselves - where development went to angular stable systems - have changed decisively. This study analyzes in a retrospective setting distal femoral fractures which were treated between 1.1.1995 and 31.9.2000 either with an internal fixator (LISS) or with conventional plate osteosynthesis. In this study 51 patients with 54 distal femoral fractures could be included. The Infection rate was non significantly lower in the LISS group (0% versus 11,1%), the rate of delayed union was non significantly higher. The only delayed union in the LISS group which needed secondary surgical intervention was seen in a patient with considerate bone loss which was not treated by primary bone grafting. Non-unions were not seen in either group. The rate of implant failure did not differ significantly. In the LISS group no secondary loss of reduction (like in the group with conventional plate osteosyntesis) was seen but proximal screw pull out due to malplacement was reported in the beginning of clinical introduction. It could be demonstrated the LISS and indirect reduction leading not to a higher rate of malalignement nor to prolonged theatre times. Functional results and the point score of the Neer Score and the Lysholm Score showed no significant difference.

This doctoral thesis is devoted to studying the possibilities of using additive manufacturing (AM) and design based on computed tomography (CT), for the production of patient-specific implants within orthopedic surgery, initially in a broad perspective and, in the second part of the thesis focusing on customized clavicle osteosynthesis plates. The main AM method used in the studies is the Electron Beam Melting (EBM) technology. Using AM, the parts are built up directly from 3D computer models, by melting or in other ways joining thin layers of material, layer by layer, to build up the part. Over the last 20 years, this fundamentally new way of manufacturing and the rapid development of software for digital 3D reconstruction of anatomical models from medical imaging, have opened up entirely new opportunities for the design and manufacturing of patient-specific implants. Based on the information in a computed tomography (CT) scan, both digital and physical models of the anatomy can be created and of implants that are customized based on the anatomical models.   The main method used is a number of case studies performed, focusing on different parts of the production chain, from CT-scan to final implant, and with several aims: learning about the details of the different steps in the procedure, finding suitable applications, developing the method and trying it out. The first study was on customized hip stems, focusing on the EBM method and its special preconditions and possibilities. It was followed by a study of bone plates, designed to follow the patient-specific bone contour, in this case a tibia fracture including the whole production chain. Further, four cases of patient-specific plates for clavicle fracture fixation were performed in order to develop and evaluate the method. The plates fit towards the patient’s bone were tested in cooperation with an orthopedic surgeon at Östersund hospital. In parallel with the case studies, a method for finite element (FE) analysis of fixation plates placed on a clavicle bone was developed and used for the comparative strength analysis of different plates and plating methods. The loading on the clavicle bone in the FE model was defined on a muscle and ligament level using multibody musculoskeletal simulation for more realistic loading than in earlier similar studies.    The initial studies (papers I and II) showed that the EBM method has great potential, both for the application of customized hip stems and bone plates; in certain conditions EBM manufacturing can contribute to significant cost reductions compared to conventional manufacturing methods due to material savings and savings in file preparation time. However, further work was needed in both of the application areas before implementation. The studies on the fracture fixation using patient-specific clavicle plates indicated that the method can facilitate the work for the surgeon both in the planning and in the operating room, with the potential of a smoother plate with a better fit and screw positioning tailored to the specific fracture (paper VI). However, a large clinical trial is required to investigate the clinical benefit of using patient-specific plates. The FE simulations showed similar stress distributions and displacements in the patient-specific plates and the commercial plates (papers III to VI).   To summarize: the results of this thesis contribute to the area of digital design and AM in patient-specific implants with broad basis of knowledge regarding the technologies used and areas in which further work is needed for the implementation of the technology on a larger scale. Further, a method has been developed and initially evaluated for implementation in the area of clavicle fracture fixation, including an approach for comparing the strength of different clavicle plates.

INTRODUÇÃO: As fraturas do terço médio da clavícula representam 80% das fraturas claviculares e seu tratamento é motivo de discussão na literatura ortopédica. Estudos prévios relativos ao tratamento cirúrgico têm demonstrado bons resultados clínicos com o uso das placas de reconstrução ou a fixação intramedular elástica estável com hastes flexíveis de titânio. O objetivo deste estudo foi a comparação desses métodos no tratamento das fraturas do terço médio da clavícula, quanto aos resultados funcionais, parâmetros radiográficos, dor pós-operatória, taxa de satisfação e taxa de complicações. MÉTODOS: Neste ensaio clínico comparativo, prospectivo e randomizado, 59 pacientes com fratura desviada do terço médio da clavícula foram alocados aleatoriamente para receberem osteossíntese com placa de reconstrução (33 pacientes - grupo Placa) ou haste flexível de titânio (26 pacientes - grupo Haste). O desfecho primário do estudo foi a avaliação funcional pelo escore DASH aos 6 meses de pós-operatório. Os desfechos secundários foram: o escore DASH aos 12 meses; o escore de Constant- Murley aos 6 e 12 meses; o tempo de consolidação da fratura; o encurtamento residual; o nível de dor pela escala visual analógica no 1º pósoperatório; a taxa de pacientes satisfeitos e a taxa de complicações. RESULTADOS: Cinquenta e quatro pacientes completaram o seguimento, sendo 29 do grupo Placa e 25 do grupo Haste. O escore DASH médio aos 6 meses foi de 9,9 pontos no grupo Placa e 8,5 no grupo Haste, sem diferença estatisticamente significante (p = 0,329). Da mesma forma, não houve diferenças significantes no escore DASH aos 12 meses ou no escore de Constant aos 6 e 12 meses. O tempo de consolidação foi equivalente entre os grupos (p = 0,352), enquanto o encurtamento residual foi maior no grupo Placa, com significância estatística (p = 0,032), mas sem relevância clínica (0,4 cm). Os resultados da escala visual analógica para dor no 1º pósoperatório e a taxa de pacientes satisfeitos foram similares entre os grupos. O grupo Placa apresentou mais casos com angulação do implante (11 casos) do que o grupo Haste (um caso) (p = 0,003), enquanto o grupo Haste foi mais associado à dor relacionada ao implante (10 casos), em comparação ao grupo Placa (4 casos) (p = 0,035). Não houve diferenças significantes entre os grupos quanto às complicações maiores, incluindo falha do implante, infecção pós-operatória, pseudoartrose e reoperação. CONCLUSÕES: A osteossíntese das fraturas desviadas do terço médio da clavícula com placa de reconstrução ou haste flexível de titânio produzem resultados semelhantes quanto aos escores funcionais, tempo de consolidação, dor pós-operatória, satisfação dos pacientes e complicações maiores. As placas de reconstrução são mais suscetíveis à angulação do implante, enquanto as hastes flexíveis de titânio causam mais dor relacionada ao implante / INTRODUCTION: Midshaft clavicle fractures represent 80% of all clavicular fractures, and their treatment is controversial in the literature. Previous studies have shown good clinical results in patients with midshaft clavicular fractures treated with reconstruction plate fixation or elastic stable intramedullary nailing (ESIN). The objective of this study was to compare these methods in terms of functional results, radiographic parameters, postoperative pain, satisfaction rates and complication rates. METHODS: In this prospective, randomized, controlled trial, 59 patients with displaced midshaft clavicular fractures were randomly assigned to receive either reconstruction plate (33 patients - Plate group) or ESIN fixation (26 patients - ESIN group). The primary outcome was the DASH score at 6 months. The secondary outcomes were the following: DASH score at 12 months; Constant-Murley scores at 6 and 12 months; time to fracture union; residual shortening; visual analog scale for pain on the first post-operative day; percentage of satisfied patients; and complications rates. RESULTS: Fifty-four patients completed the follow-up, 29 in the Plante group and 25 in the ESIN group. The mean DASH score at 6 months was 9.9 in the plate group and 8.5 in the ESIN group, with no significant difference (p = 0.329). Similarly, there were no differences in the DASH score at 12 months or the Constant-Murley scores at 6 and 12 months. The time to union was equivalent between the groups (p = 0.352), whereas the residual shortening was significantly greater in the plate group (p = 0.032) but was not clinically relevant (0.4 cm). The visual analog scale scores for pain and the percentage of satisfied patients were similar between the groups. Implant bending was significantly more common in the plate group (eleven patients) than in the ESIN group (one patient) (p = 0.003), whereas hardware-related pain was more frequent in the ESIN group (10 patients vs. 4 patients) (p = 0.035). There were no differences in terms of major complications, including implant failure, postoperative infection, nonunion and reoperation. CONCLUSIONS: Reconstruction plates and ESIN yielded similar results in terms of functional results, time to union, post-operative pain, patient satisfaction and major complications in patients with displaced midshaft clavicular fractures. Reconstruction plates are more susceptible to implant bending, whereas ESIN causes more hardwarerelated pain

INTRODUÇÃO: As fraturas do terço médio da clavícula representam 80% das fraturas claviculares e seu tratamento é motivo de discussão na literatura ortopédica. Estudos prévios relativos ao tratamento cirúrgico têm demonstrado bons resultados clínicos com o uso das placas de reconstrução ou a fixação intramedular elástica estável com hastes flexíveis de titânio. O objetivo deste estudo foi a comparação desses métodos no tratamento das fraturas do terço médio da clavícula, quanto aos resultados funcionais, parâmetros radiográficos, dor pós-operatória, taxa de satisfação e taxa de complicações. MÉTODOS: Neste ensaio clínico comparativo, prospectivo e randomizado, 59 pacientes com fratura desviada do terço médio da clavícula foram alocados aleatoriamente para receberem osteossíntese com placa de reconstrução (33 pacientes - grupo Placa) ou haste flexível de titânio (26 pacientes - grupo Haste). O desfecho primário do estudo foi a avaliação funcional pelo escore DASH aos 6 meses de pós-operatório. Os desfechos secundários foram: o escore DASH aos 12 meses; o escore de Constant- Murley aos 6 e 12 meses; o tempo de consolidação da fratura; o encurtamento residual; o nível de dor pela escala visual analógica no 1º pósoperatório; a taxa de pacientes satisfeitos e a taxa de complicações. RESULTADOS: Cinquenta e quatro pacientes completaram o seguimento, sendo 29 do grupo Placa e 25 do grupo Haste. O escore DASH médio aos 6 meses foi de 9,9 pontos no grupo Placa e 8,5 no grupo Haste, sem diferença estatisticamente significante (p = 0,329). Da mesma forma, não houve diferenças significantes no escore DASH aos 12 meses ou no escore de Constant aos 6 e 12 meses. O tempo de consolidação foi equivalente entre os grupos (p = 0,352), enquanto o encurtamento residual foi maior no grupo Placa, com significância estatística (p = 0,032), mas sem relevância clínica (0,4 cm). Os resultados da escala visual analógica para dor no 1º pósoperatório e a taxa de pacientes satisfeitos foram similares entre os grupos. O grupo Placa apresentou mais casos com angulação do implante (11 casos) do que o grupo Haste (um caso) (p = 0,003), enquanto o grupo Haste foi mais associado à dor relacionada ao implante (10 casos), em comparação ao grupo Placa (4 casos) (p = 0,035). Não houve diferenças significantes entre os grupos quanto às complicações maiores, incluindo falha do implante, infecção pós-operatória, pseudoartrose e reoperação. CONCLUSÕES: A osteossíntese das fraturas desviadas do terço médio da clavícula com placa de reconstrução ou haste flexível de titânio produzem resultados semelhantes quanto aos escores funcionais, tempo de consolidação, dor pós-operatória, satisfação dos pacientes e complicações maiores. As placas de reconstrução são mais suscetíveis à angulação do implante, enquanto as hastes flexíveis de titânio causam mais dor relacionada ao implante / INTRODUCTION: Midshaft clavicle fractures represent 80% of all clavicular fractures, and their treatment is controversial in the literature. Previous studies have shown good clinical results in patients with midshaft clavicular fractures treated with reconstruction plate fixation or elastic stable intramedullary nailing (ESIN). The objective of this study was to compare these methods in terms of functional results, radiographic parameters, postoperative pain, satisfaction rates and complication rates. METHODS: In this prospective, randomized, controlled trial, 59 patients with displaced midshaft clavicular fractures were randomly assigned to receive either reconstruction plate (33 patients - Plate group) or ESIN fixation (26 patients - ESIN group). The primary outcome was the DASH score at 6 months. The secondary outcomes were the following: DASH score at 12 months; Constant-Murley scores at 6 and 12 months; time to fracture union; residual shortening; visual analog scale for pain on the first post-operative day; percentage of satisfied patients; and complications rates. RESULTS: Fifty-four patients completed the follow-up, 29 in the Plante group and 25 in the ESIN group. The mean DASH score at 6 months was 9.9 in the plate group and 8.5 in the ESIN group, with no significant difference (p = 0.329). Similarly, there were no differences in the DASH score at 12 months or the Constant-Murley scores at 6 and 12 months. The time to union was equivalent between the groups (p = 0.352), whereas the residual shortening was significantly greater in the plate group (p = 0.032) but was not clinically relevant (0.4 cm). The visual analog scale scores for pain and the percentage of satisfied patients were similar between the groups. Implant bending was significantly more common in the plate group (eleven patients) than in the ESIN group (one patient) (p = 0.003), whereas hardware-related pain was more frequent in the ESIN group (10 patients vs. 4 patients) (p = 0.035). There were no differences in terms of major complications, including implant failure, postoperative infection, nonunion and reoperation. CONCLUSIONS: Reconstruction plates and ESIN yielded similar results in terms of functional results, time to union, post-operative pain, patient satisfaction and major complications in patients with displaced midshaft clavicular fractures. Reconstruction plates are more susceptible to implant bending, whereas ESIN causes more hardwarerelated pain

The present work deals with the comparison of the properties of metallic biomaterials in terms of their suitability for use as a temporary metal implant. In the work is judged biocompatibility of materials, they are comparing the corrosion rates and the influence of additives in the iron alloy to change biocompatibility and corrosion rate. In a part of this work is suggesting a method of preparing biodegradable metallic samples with different alloying elements and determine the methods, processes and measuring the corrosion rates. Part of this work is the chapter dealing with the function and effect of iron in the human body and any complications that may occur when a surplus caused by the release of part of the implant during its degradation or corrosion products. The outcome of this work is sort of created an iron-based samples in terms of their electrochemical corrosion potential, corrosion rate of samples exposed in various corrosive solutions, spectroscopic elemental analysis and outputs from the microscopic observation of the structures.

Παρά τον μεγάλο όγκο της βιβλιογραφίας σχετικά με τα αποτελέσματα της αντιμετώπισης των ασταθών καταγμάτων του περιφερικού άκρου της κερκίδας με κλειστή ανάταξη και ελάχιστα επεμβατική οστεοσύνθεση υπάρχουν ακόμα σημαντικά αναπάντητα ερωτήματα. Πιό συγκεκριμένα, δεν υπάρχουν επαρκή στοιχεία γιά τον ρυθμό αποκατάστασης των κλινικών παραμέτρων κατά τη διάρκεια της μετατραυματικής περιόδου, γιά το τελικό αποτέλεσμα όπως εκφράζεται από τους ασθενείς με τη χρήση κλιμάκων αυτο-αξιολόγησης, καθώς και γιά τον βαθμό επίδρασης συγκεκριμένων ακτινολογικών παραμέτρων στο τελικό λειτουργικό αποτέλεσμα. Επίσης, δεν έχει διερευνηθεί ο συσχετισμός μεταξύ της ακτινολογικής παραμέτρου της παλαμιαίας γωνίας του περιφερικού άκρου της κερκίδας και των φορτίων που αναπτύσσονται στην φυσιολογική κερκιδοκαρπική άρθρωση. Η εργασία αυτή αποτελεί μία προοπτική μελέτη ασταθών καταγμάτων του περιφερικού άκρου της κερκίδας που αντιμετωπίστηκαν με κλειστή ανάταξη και ελάχιστα επεμβατική (διαδερμική) οστεοσύνθεση. Έγινε ανάλυση ακτινολογικών και κλινικών παραμέτρων καθώς και χρησιμοποίηση κλίμακας αυτο-αξιολόγησης της δυσλειτουργίας της πηχεοκαρπικής άρθρωσης γιά συνολικό διάστημα ενός έτους μετά τον τραυματισμό. Τα αποτελέσματα έδειξαν ότι ο ‘τυπικός’ ρυθμός μετατραυματικής αποκατάστασης αντιστοιχεί σε ταχεία κλινική βελτίωση κατά τη διάρκεια των τριών πρώτων μηνών ακολουθούμενη από ήπιου βαθμού δυσλειτουργία. Ωστόσο σημαντική δυσλειτουργία παραμένει σε 10% των ασθενών ένα έτος μετά τον τραυματισμό. Επίσης, τα αποτελέσματα δείχνουν σημαντικές διαφορές στο βαθμό κατά τον οποίο ο περιορισμός συγκεκριμένων αντικειμενικών κλινικών παραμέτρων αντανακλά το επίπεδο δυσλειτουργίας της πηχεοκαρπικής άρθρωσης. Ακτινολογικά, η μόνιμη απώλεια της παλαμιαίας γωνίας, η κερκιδική βράχυνση και η παρουσία ανωμαλίας της αρθρικής επιφάνειας της πηχεοκαρπικής με αρθρικό ‘βήμα’ τουλάχιστον ενός χιλιοστού σχετίζονται με επιμένοντα συμπτώματα πόνου και δυσλειτουργίας, ενώ δεν υπάρχει εμφανής συσχέτιση μεταξύ του τύπου του κατάγματος και του τελικού λειτουργικού αποτελέσματος. Επιπλέον, ανάλυση δυνάμεων της φυσιολογικής πηχεοκαρπικής άρθρωσης έδειξε φορτίσεις που μπορεί να φθάνουν έως 4,2 φορές το ανυψούμενο βάρος, αντίστροφο συσχετισμό μεταξύ της παλαμιαίας γωνίας του περιφερικού άκρου της κερκίδας και του μέγιστου φορτίου στην κερκιδοκαρπική άρθρωση καθώς και μη σημαντική διαφορά μεταξύ της γωνίας διεύθυνσης του μέγιστου φορτίου της κερκιδοκαρπικής και της παλαμιαίας γωνίας του περιφερικού άκρου της κερκίδας. / Despite the large volume of published literature on the results of management of unstable fractures of the distal radius using closed reduction and minimally invasive fixation there are still significant unanswered questions. More specifically, there is no sufficient evidence about the rate of recovery of the clinical parameters over the post-traumatic period, the final outcome as expressed by the patients using self-assessment scores and the degree that specific radiographic parameters influence the final functional outcome. Furthermore, the correlation between the radiographic parameter of volar tilt of the distal radius and the normal loads in the radiocarpal joint has not been investigated. The present thesis is a prospective study of unstable fractures of the distal radius managed with closed reduction and minimally invasive (percutaneous) fixation. Analysis of radiographic and clinical parameters as well as of patient-rated wrist dysfunction score for one year following injury was carried out. The results showed that a ‘typical’ rate of post-traumatic recovery corresponds to an initial rapid clinical improvement for the first three months followed by mild wrist dysfunction. However, significant dysfunction persists in 10% of patients one year following injury. Furthermore, the results showed significant differences in the degree to which the restriction of specific objective clinical parameters reflected the level of wrist dysfunction. Regarding the radiographic parameters, permanent loss of palmar tilt of the distal radius, radial shortening and the presence of articular incongruency with an articular ‘step off’ of at least 1 mm correlate with persisting pain and dysfunction while there is no obvious correlation between the fracture type and the final functional outcome. Moreover, force analysis in the normal wrist showed loads as high as 4.2 times the lifted weight, a reverse relationship between the angle of palmar tilt of the distal radius and the maximum radiocarpal load as well as a nonsignificant difference between the angle of the maximum radiocarpal force and the angle of palmar tilt of the distal radius.

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