[Truncated abstract] First metatarsophalangeal joint (MTPJ1) motion is an important factor in normal weight transference during walking. Disruptions to normal range can influence joints both proximal and distal to the MTPJ1, potentially leading to pain and dysfunction. Whilst the MTPJ1 has been investigated significantly, the numerous methodologies described to quantify range of motion can be questioned and makes comparisons difficult. Range of MTPJ1 motion is commonly assessed in a clinical setting to determine pathology as well as to make decisions on appropriate intervention. The anatomical and biomechanical influence of tendo Achilles load and MTPJ1 motion has been well described; however few studies measuring MTPJ1 range control for Achilles load or describe ankle joint positioning. Further to this the effects of reducing tendo Achilles stiffness on MTPJ1 extensions has yet to be investigated. The purpose of this study was to describe a technique to quantify passive MTPJ1 extension and to determine the influence of ankle joint position on joint range. Secondly the effect of calf muscle stretching on MTPJ1 range was also investigated. The information gathered will assist both research and clinical protocols for quantifying MTPJ1 range, and provide a greater understanding of the anatomic and biomechanical relationship between tendo Achilles load and MTPJ1 extension. In order to fulfil the purposes of the study it was necessary to establish a reliable methodology to quantify non weight bearing MTPJ1 extension. Reliability testing was undertaken in three parts. '...' The results demonstrated a statistically significant increase in joint range immediately following a one minute stretch for variables ankle joint range of motion as well as MTPJ1 extension for ankle joint plantar flexed at 10 Newton's and ankle joint neutral and plantar flexed at 30 Newtons. No significant differences were noted in ankle or MTPJ1 range of motion in either the control group on immediate re-testing, or in both groups after a one week stretch program. The findings of this study support those documented in the literature pertaining to the ankle joint position, tendo Achilles load and plantar fascial stiffness to MTPJ1 range of motion. Increased stiffness at the MTPJ1 was noted dependant on ankle joint position from ankle joint plantar flexion through to ankle joint dorsiflexion. This appears most likely due to increases in tendo Achilles load and subsequent forces transmitted to the plantar aponeurosis. The present study also demonstrated a trend towards increased joint extensibility and limb dominance. The study also supports previous literature into gender differences and joint extensibility, with a positive trend towards increased MTPJ1 range evident in the female subjects tested. The study also demonstrated the immediate effect of calf muscle stretching on ankle and MTPJ1 range of motion. It remains however unclear as to the exact mechanisms involved in producing increased joint range be it reflex inhibition or actual changes to the viscoelastic properties of the soft tissues. Despite this, no changes were evident following a one week stretching program, which supports previous literature describing a short lag time before soft tissues revert to baseline length properties following a single stretch session.

Bakalauro darbe analizuojamas kineziterapijos poveikis pėdos funkcijai gydant didžiojo piršto iškrypimą. Šio darbo objektas - pėdos didžiojo piršto iškrypimo laipsnio, pėdos skausmo, raumenų jėgos, krūvio pasiskirstymo pade, pado svorio centro trajektorijos, pėdos sąlyčio su judėjimo paviršiumi būklės skirtingose ėjimo ciklo fazėse pokytis po gydymo. Tyrimo uždavianiai - išanalizuoti mokslinę literatūrą apie pėdos didžiojo piršto iškrypimo, pėdos funkcijos sampratą, bei gydymą. Išsiaiškinti pėdos didžiojo piršto iškrypimo laipsnio, skausmo intensyvumo, raumenų jėgos pokyčius prieš ir po kineziterapinių procedūrų taikymo. Įvertinti tiriamųjų krūvio pasiskirstymą pade, pado svorio centro trajektoriją, pėdos sąlyčio su judėjimo paviršiumi būklę skirtingose ėjimo ciklo fazėse prieš ir po kineziterapinių procedūrų taikymo. Tyrimas buvo atliekamas viešojoje įstaigoje Respublikinėje Šiaulių ligoninėje Ambulatorinės reabilitacijos centre. Kompiuterinį padobarografinį pėdos vertinimą atliko Bauerfeind atstovė, Manualinės medicinos klinikoje. Tyrimas buvo atliekamas 2013 – 2014 metų gruodžio – balandžio mėnesiais. Tyrime dalyvavo 12 tiriamųjų, turinčių pėdos didžiojo piršto iškrypimo deformaciją. Užsiėmimų laikas truko 11 savaičių. Pacientams buvo testuojamas pėdos didžiojo piršto iškrypimo laipsnis, raumenų jėga, vertinamas skausmo intensyvumas, krūvio pasiskirstymas pade, pado svorio centro trajektorija, pėdos sąlytis su judėjimo paviršiumi prieš procedūras ir po jų. ... [toliau žr. visą tekstą] / The present final paper presents an analysis of the effects of fisiotherapy on foot function when treating the hallux valgus deformity. The research object is the change of the deformity degree of the great toe, foot pain, muscle strength, load distribution in the sole, trajectory of the sole’s center of gravity and foot’s contact with the movement’s surface in different stages of walking after the treatment. Objectives of the research: analyze scientific literature about the hallux valgus, the concept of foot function and its treatment; determine the changes in the deformity degree of the great toe, pain intensity and muscle strength prior to and after the fisioitherapy exercises; assess the load distribution in the soles of the respondents, trajectory of the sole’s center of gravity and foot’s contact with the movement’s surface in different stages of walking prior to and after the fisiotherapy exercises. The study was carried out at the Out-Patient Recuperation Center of the Public Institution Šiauliai National Hospital. The computer-aided pedobarographic assessment of the foot was performed by a representative of the Bauerfeind Company at the Manual Medicine Clinic. The study was carried out from December 2013 to April 2014. Twelve respondents afflicted with hallux valgus deformity participated in the study. The duration of the exercise sessions was 11 weeks. According to the analysis of the research data, the intensity of pain was influenced by both the... [to full text]

[Truncated abstract] Limitation of sagittal plane dorsiflexion, or hallux limitus (HL), represents the second most commonly encountered pathomechanical disorder affecting the first metatarsophalangeal joint, after hallux valgus (HV). The kinematic role of the first metatarsophalangeal joint represents an integral component of the gait cycle. It has often been reported that for adequate leverage and propulsion to occur during normal gait, the hallux must be able to dorsiflex approximately 65° on the head of the first metatarsal. Secondary gait compensation mechanisms have often been observed clinically as a result of HL. The effect of HL on gait can be reflected in transverse plane alteration of the foot in relation to the line of progression during gait, defined as the angle of gait (AOG). The first purpose of this study served to investigate potential differences in dynamic angle of gait AOG in subjects with HL compared to a control group. A validated technique using coloured powdered footprints was used to quantify AOG. Furthermore, it was required to establish whether the relative amount of transverse plane motion observed in the AOG was related to factors intrinsic or extrinsic to the foot. Intrinsic factors such as the amount of forefoot to rearfoot abduction was considered, and achieved by measuring the rearfoot to forefoot axis (RFA) angle using a weight bearing composite (COMP) view radiograph. The remaining objectives of the study served to investigate other common aetiological factors associated with HL and their potential influence on AOG in subjects with HL ... Results further indicated that the amount of first metatarsophalangeal joint dorsiflexion did not appear to influence AOG in the two groups, and that AOG did not reflect the iii amount of forefoot to rearfoot abduction in a foot with HL compared to the control group. When comparing foot type, as indicated by CIA, it appeared AOG did not significantly alter between the HL and control groups. Finally, the results indicated AOG did not differ significantly between subjects with unilateral HL. This thesis study indicated that with the current sample population, the wide variability in AOG prevented detection of any subtle differences that may exist in subjects with HL. Results also emphasised the need to incorporate other variables such as symptomology and foot dominance when considering the effects first metatarsophalangeal joint pathology might have on HL, such as AOG.

[Truncated abstract] Hallux valgus (HV) is one of the most common foot deformities encountered in clinical practice. This complex deformity primarily affects the first metatarsophalangeal joint (MPJ), leading to altered foot structure and function. By virtue of the lateral displacement of the hallux on the first metatarsal, HV has the potential to influence adjacent joints of the foot. In doing so, function of the foot may be altered, and clinically this may result in abduction of the foot during the stance phase of gait. However the relationship between an abducted angle of gait (AOG) and HV has never been substantially examined. The purpose of this study is to investigate the relationship between HV and AOG, and determine if specific radiographic features are associated with the deformity or with a particular AOG. Such information would assist in understanding aetiological factors and the effects of intervention to treat the deformity ... Length and elevation of the first metatarsal were associated in subjects with HV, implying that length of the metatarsal may be related to whether or not it becomes elevated (R: 0.50, CI: 0.21, 0.71, P< 0.05). Similarly, an association was found between length of the first metatarsal and the amount of first MPJ dorsiflexion, suggesting perhaps length of the metatarsal has implications for first MPJ range of motion (R: -0.37, CI: -0.62, -0.04, P<0.05). However the amount of first MPJ dorsiflexion did not influence the AOG in HV subjects when compared to the control group. First MPJ dorsiflexion was also associated with the first intermetatarsal angle. Interestingly, the HV group alone did not show an association between the hallux abductus angle and the first intermetatarsal angle. The findings of this study are contrary to those suspected in clinical practice and alluded to in the literature. Despite the documented support for the biomechanical causes of HV, an abducted AOG was not significantly different in HV subjects when compared to controls. Possible explanations may have related to limitations of the present study including the size and gender demographics of the sample population, and greater variability in normal AOG ranges than reported in the literature. The present study indicated a possible need to gather information regarding foot dominance and leg length; factors extrinsic to the foot capable of influencing transverse plane orientation of the foot; and, the influence of symptoms and subsequent compensatory mechanisms adopted during gait.

INTRODUÇÃO: O hallux valgus é a deformidade mais comum do pé do adulto e é frequentemente incapacitante requerendo tratamento cirúrgico. O ângulo articular metatarsal distal (AAMD) é uma das variáveis importantes no estudo da deformidade, mas possui baixa correlação interobservadores quando avaliado pela radiografia. O objetivo deste estudo foi avaliar um método tomográfico de aferir este ângulo comparando-o com a medida radiográfica existente. MATERIAL E MÉTODOS: O AAMD de 77 pés ( X pacientes) foram avaliados através de tomografia computadorizada por dois observadores. Os valores encontrados foram comparados entre os observadores e entre a medição radiográfica utilizando o coeficiente de correlação e concordância (CCC) proposto por King e análise de Bland-Altmann para concordância entre os métodos. RESULTADOS: Foi encontrado índice de concordância alto na medição tomográfica entre os observadores com CCC = 0,90 e p < 0,001. Em relação a mensuração radiográfica com a tomográfica houve uma concordância com CCC = 0,667 de com p < 0,001. Na análise gráfica de Bland-Altman a presença de round sign positivo sugere um aumento da diferença da medição radiográfica com a tomográfica e está associado a valor alto do AAMD. CONCLUSÃO: A mensuração do AAMD pelo método tomográfico demonstrou maior correlação interobservadores do que o método radiográfico. Em casos em que há dúvida sobre alteração patológica da inclinação da cabeça metatarsal com ângulos articulares metatarsais distais (AAMD) elevados e, principalmente, com a presença de round sign positivo, a tomografia pode ser um método alternativo para planejamento cirúrgico pré-operatório.

Made available in DSpace on 2016-12-06T17:07:19Z (GMT). No. of bitstreams: 1 Juliana Motta Costa.pdf: 2688203 bytes, checksum: 74d387f1f098f8d4cb18d76551a28d99 (MD5) Previous issue date: 2009-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to evaluate and correlate the clinical and baropodometric characteristics of gait of subjects diagnosed with a hallux valgus deformity and verify the influence of surgical correction procedure. The participants were 26 women with different levels of hallux valgus deformity, from an orthopedic clinic in Florianopolis. The same surgical procedure for correction was made in 16 women, who were reevaluated three months after the surgery. Twenty six healthy women, without deformities on feet and lower limbs, formed the control group. Data acquisition took place at Biomechanics Laboratory of CEFID/UDESC. Instruments utilized were the American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal Interphalangeal (AOFAS-HMI) scoring system, radiographs, a goniometer and Emed-at baropodometric platform (Novel, Gmbh, Germany). The analyzed clinical parameters were Range of Motion and radiographic measurements, such as the Hallux Valgus Angle (HVA) and Intermetatarsal Angle (IMA). The baropodometric evaluation analyzed Plantar Peak of Pressure (PPP), Mean Plantar Pressure (MPP), Contact Area (CA), Contact Time (CT), Pressure-Time Integral (PTI), Relative Load (RL), Medial-Lateral COP Displacement (COPD) and Plantar Arch Index (PAI). Descriptive statistics included mean, standard deviation, minimum and maximum. In order to verify the data normality, Shapiro-Wilk Test was used. To verify the relation between radiographic variables and baropodometric ones, Spearman´s rank Correlation Coefficient was calculated. For the variable comparison between the hallux valgus group and the control one, Independent t Test or Mann-Whitney U Test were used. For the comparison of the variables before and after the surgical procedure for correction, dependent t Test or Wilcoxon Test were calculated. The adopted confiability for all comparisons was 95%. When compared to the control group, the hallux valgus participants showed an increase of PPP, MPP, PTI on first and second metatarsal regions and lateral toes. As well as a reduction on MPP and RL on fourth metatarsal and hallux. Spearman´s Correlation Coefficient value shows a weak, positive and significant relation between HVA and MPP on first and fifth metatarsal bones and on third to fifth toes, as well as a weak, negative and significant relations between these variables on hallux. IMA did not show a significant correlation with any baropodometric variables. After Chevron osteotomy, a significant raise in AOFAS mean score and a significant correction of the deformity were seen, reducing HVA and IMA values. Concerning the baropodometric variables, a significant reduction was seen in PPP, MPP, PTI and RL under the first metatarsal, hallux and second to fifth toes, and a significant raise of the same variables under the fourth and fifth metatarsal bones and PTI and RL under the midfoot, second, third, fourth and fifth metatarsal bones. Furthermore, the load transference from medial to lateral region of forefoot was related to pain, lack of mobility and incapacity in transferring the load to the operated region. It was concluded that people with hallux valgus show an overload on medial and central metatarsal bones and a reduction of load on lateral metatarsal bones and an inefficacy of hallux in propulsion phase of gait, which is compensated by the other toes. Concerning the surgical correction procedure, the results demonstrated an efficacy in influencing clinical and baropodometric variables of gait. An improvement on clinical conditions of the patients was evident, as much as the deformity correction, however, the surgical procedure was not able to normalize the plantar load distribution pattern in a short-term period. / O objetivo deste estudo foi avaliar e relacionar as características clínicas e baropodométricas da marcha de indivíduos com deformidade de hálux valgo e verificar a influência de um procedimento cirúrgico de correção nessas características. Participaram da pesquisa 26 mulheres com diferentes graus de deformidade de hálux valgo, procedentes de uma clínica de ortopedia, localizada em Florianópolis. O mesmo procedimento cirúrgico de correção foi realizado em 16 mulheres, as quais, foram reavaliadas em 3 meses de pós-operatório. Também foram avaliadas 26 mulheres saudáveis, sem deformidades nos pés ou membros inferiores, as quais formaram um grupo controle. As coletas de dados foram realizadas no Laboratório de Biomecânica do CEFID/UDESC. Foram utilizados como instrumentos a avaliação clínica para hálux, metatarsofalangeana e interfalangeana, proposta pela American Organization of Foot and Ankle Society (AOFAS), as imagens radiográficas, um goniômetro e uma plataforma baropodométrica Emed-at (Novel Gmbh, Alemanha). Foram avaliados parâmetros clínicos como, amplitude de movimento do hálux e medidas radiográficas, como Ângulo de Valgismo do Hálux (AVH) e Ângulo Intermetatarsal (AIM). Na avaliação baropodométrica foram analisados o Pico de Pressão Plantar (PPP), Pressão Plantar Média (PPM), Área de Contato (AC), Tempo de Contato (TC), Integral Pressão-Tempo (IPT), Carga Relativa (CR), Deslocamento Medial e Lateral do COP (DCOP) e Índice de Arco Plantar (IAP). Para o tratamento estatístico dos dados foi utilizada a estatística descritiva: média, desvio padrão, mínimo e máximo. Para atestar a normalidade dos dados foi utilizado o teste de Shapiro-wilk. Para verificar a relação entre as variáveis radiográficas e as variáveis baropodométricas foi utilizado o Coeficiente de Correlação de Spearman. Para comparação das variáveis entre os grupos com hálux valgo e grupo controle, foram utilizados o Teste-t independente ou teste U de Mann-Whitney. Para comparação das variáveis antes e após o procedimento cirúrgico de correção, foi utilizado o Teste-t dependente ou o teste de Wilcoxon. O nível de confiança adotado para todas as comparações foi de 95%. Quando comparados com o grupo controle os indivíduos com hálux valgo apresentaram um aumento da PPP, PPM e IPT na região do 1º e 2º metatarsos e dedos laterais. Assim como, redução do PPM e CR na região do 4º metatarso e do hálux. Os resultados da correlação indicam que existe uma relação fraca, positiva e significativa entre o AVH e a PPM na região do 1° e 5º metatarso e do 3-5º dedos, assim como, uma relação fraca, negativa e significativa entre essas variáveis na região do hálux. O AIM não apresentou correlação significativa com nenhuma das variáveis baropodométricas. Após a osteotomia de Chevron houve aumento significativo na pontuação média da AOFAS e correção significativa da deformidade com redução do AVH e do AIM. Em relação às variáveis baropodométricas houve uma redução significativa do PPP, PPM, IPT e CR sob o 1º metatarso, hálux e 2-5º dedos, e aumento significativo destas variáveis sob o 4º e 5º metatarsos e da IPT e CR sob o mediopé, 2°, 3°, 4° e 5° metatarsos. Portanto, ocorreu uma transferência de cargas da região medial para lateral do antepé a qual foi relacionada à dor, falta de mobilidade e incapacidade de transferir a carga para região operada. Concluiu-se que os indivíduos com hálux valgo apresentam uma sobrecarga nos metatarsos mediais e centrais com redução da carga nos metatarsos laterais, além de uma ineficiência do hálux, na fase de propulsão da marcha, que é compensada pelos demais dedos. Em relação ao procedimento cirúrgico de correção os resultados demonstraram que ele foi capaz de influenciar as variáveis clínicas e baropodométricas da marcha. Verificou-se melhora no quadro clínico das pacientes com correção da deformidade, no entanto, a cirurgia não foi capaz de normalizar o padrão de distribuição das cargas plantares, em curto prazo.

INTRODUÇÃO: O hallux valgus é a deformidade mais comum do pé do adulto e é frequentemente incapacitante requerendo tratamento cirúrgico. O ângulo articular metatarsal distal (AAMD) é uma das variáveis importantes no estudo da deformidade, mas possui baixa correlação interobservadores quando avaliado pela radiografia. O objetivo deste estudo foi avaliar um método tomográfico de aferir este ângulo comparando-o com a medida radiográfica existente. MATERIAL E MÉTODOS: O AAMD de 77 pés ( X pacientes) foram avaliados através de tomografia computadorizada por dois observadores. Os valores encontrados foram comparados entre os observadores e entre a medição radiográfica utilizando o coeficiente de correlação e concordância (CCC) proposto por King e análise de Bland-Altmann para concordância entre os métodos. RESULTADOS: Foi encontrado índice de concordância alto na medição tomográfica entre os observadores com CCC = 0,90 e p < 0,001. Em relação a mensuração radiográfica com a tomográfica houve uma concordância com CCC = 0,667 de com p < 0,001. Na análise gráfica de Bland-Altman a presença de round sign positivo sugere um aumento da diferença da medição radiográfica com a tomográfica e está associado a valor alto do AAMD. CONCLUSÃO: A mensuração do AAMD pelo método tomográfico demonstrou maior correlação interobservadores do que o método radiográfico. Em casos em que há dúvida sobre alteração patológica da inclinação da cabeça metatarsal com ângulos articulares metatarsais distais (AAMD) elevados e, principalmente, com a presença de round sign positivo, a tomografia pode ser um método alternativo para planejamento cirúrgico pré-operatório.

L’hallux de l’humain (plus couramment appelé gros orteil) est aujourd’hui aligné avec les autres orteils ce qui rend son opposition aux autres orteils impossible. Il a été proposé que la perte de l’opposabilité de l’hallux, chez les premiers hominines, aurait mené à une augmentation des coûts liés à la maternité, due à l’obligation de transporter activement les juvéniles lors de longs trajets (Tanner & Zihlman 1976 ; Wall-Sheffler 2007 ; Watson et al. 2008). Cela suggère que l’Australopithecus afarensis devait transporter activement son juvénile car il ne pouvait pas se maintenir par lui-même lors des transports. Mon étude propose de vérifier cette hypothèse en déterminant si un primate juvénile a besoin de son hallux pour s’accrocher au poil de sa mère. Les deux hypothèses de ce travail sont donc les suivantes : L’abduction de l’hallux est nécessaire à la préhension du poil d’un porteur (généralement la mère) par les jeunes macaques et l’abduction de l’hallux n’est pas nécessaire à la préhension du poil d’un porteur (généralement la mère) par les jeunes macaques lors des transports. L’observation de vidéos de dyades mère/enfant de macaques rhésus vivant en liberté à Cayo Santiago (Costa Rica) filmées sur une période de cinq mois, tend à supporter mon hypothèse. En effet, les résultats de mon étude montrent que les macaques rhésus sont capables de s’accrocher, et se maintenir, par eux-mêmes à leur mère durant les transports sans se servir de leur hallux. Il serait cependant nécessaire de compléter cette étude par des recherches supplémentaires pour inférer avec plus de confiance ce type de comportement à l’A. afarensis. / The human hallux (more commonly called big toe) is now aligned with the other toes, which makes its opposition to other toes impossible. It has been proposed that the loss of opposability of the hallux in early hominins would have led to increase the energetic costs related to maternity, due to the obligation to carry juveniles actively (Tanner & Zihlman 1976; Wall-Sheffler 2007, Watson et al. 2008). This implies that Australopithecus afarensis juveniles had to be actively transported instead of grasping their mother's hair. My study proposes to test whether a juvenile primate needs its hallux to cling to the hair of its mother. The two hypotheses of this work are as follows: The abduction of the hallux is essential for the grasping of the hair of a carrier (usually the mother) by the young macaques and the abduction of the hallux is not necessary for the grasp of the hair of a carrier (usually the mother) by young macaques during transport. Videos of mother/child dyads of rhesus macaques are used in this study to evaluate the use of the hallux in juveniles being carried. The macaques are from a free-range colony in Cayo Santiago, Costa Rica, and they were filmed over a 5-month period. Results tend to support my hypothesis. Indeed, rhesus macaques are able to cling and maintain themselves on their mother during transport without using their hallux. It would, however, be necessary to supplement this study with further research in order to infer this type of behavior in A. afarensis.

付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第22388号 / 人健博第74号 / 新制||人健||5(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 黒木 裕士, 教授 高桑 徹也, 教授 妻木 範行 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM

The present study utilizes finite element analysis in order to simulate a surgical operation in the treatment of a hallux rigidus case, as designed and developed by Episurf Medical AB (Stockholm, Sweden). The surgical intervention includes an initial cheilectomy as well as an insertion of an orthopedic implant. The goal of the study was to evaluate the current concept of the medical intervention as it is manifested today, as well as to give design suggestions as how to further improve the pre-planning of the surgery. MRI-images of the first metatarsophalangeal joint in the hallux was collected from a patient suffering from hallux rigidus, and used in order to build case-specific geometrical images to be used in the FE analysis. The simulation was setup as to simulate a normal motion in the first metatarsophalangeal joint during a normal gait pattern. The first simulation was conducted without any intervention, while the second was conducted after a pre-determined operation plan in accordance with the surgical operation that Episurf Medical AB wants to perform. The results was then compared and analyzed in order to determine the post-surgical effects that such an operation could have on the patient. A third and final simulation was then performed, by using optimization algorithms in order to make suggestions to the pre-planned cheilectomy shape, as well as orientation of the implant. Two parameters were being investigated in order to assess the surgical intervention as designed by Episurf Medical AB; the contact stress on the articular side of the metatarsal head, and the strain on the implant shaft. The current manifestation of the cheilectomy did not reduce the contact stress compared to the untreated condition, as the implant failed to be a load baring surface due to the two dimensional nature of which it is conceived. Instead, the contact surface area is reduced and positioned medial and lateral to the implant head. The optimization algorithm could reduce the maximum contact stress significantly, from 295MPa and 400MPa in the treated and untreated conditons respectively, to 160MPa after the optimization algorithm. It became clear that the angle of the cheilectomy as well as the orientation of the implant angle has an incriminating effect on the post-operative results. However, the shape of the cheilectomy as well as the design of the implant would need to be revised in future embodiments, as the current concept failed to provide joint with a new articulating surface. Further development of the models formulated in this thesis is advised, as well as validating the findings with clinical data. / Den aktuella studien använder finita elementmetoden i syfte att simulera en kirurgisk operation som har utvecklats av Episurf Medical AB (Stockholm, Sverige) för att behandla ett hallux rigidus fall. Det kirurgiska ingreppet utgörs av en inledande cheilectomi,  som sedan följs av att operera in ett ortopediskt implantat. Målet med studien var att utvärdera det nuvarande konceptet för det medicinska ingrepp så som den är uttänkt idag, samt att ge designförslag för hur man ytterligare kan förbättra planeringen av operationen. MR-bilder av den första metatarsalleden i stortån samlades in från en patient som lider av hallux rigidus, som användes sedan för att bygga patient specifika geometriska bilder för att användas i FE-analysen. Simuleringen var modellerad för att simulera en normal rörelse i första metatarsofalangealleden under en normal gångcykel. Den första simuleringen genomfördes utan något ingripande, medan den andra genomfördes efter en förutbestämd operationsplan i enlighet med det kirurgiska ingreppet som Episurf Medical AB vill utföra. Resultaten jämfördes sedan och analyserades för att bestämma de resultaten som en sådan operation skulle kunna innebära för patienten postoperativt. En tredje och sista simulering utfördes sedan, med hjälp av optimeringsalgoritmer för att ge förslag på förbättringar för den förplanerade cheilectomin, samt orienteringen av implantatet. Två parametrar undersöktes för att bedöma det kirurgiska ingrepp som designats av Episurf Medical AB, kontaktbelastningen på artikulära sidan av metatarsalhuvudet, och påfrestningen på implantatet. Den nuvarande utformningen av cheilectomin minskade inte kontaktbelastningen jämfört med det obehandlade tillståndet, då implantatet inte vart belastat på grund av den tvådimensionella profilen i dess utformning. Optimeringsalgoritmen kunde minska den maximala kontaktbelastningen markant, från 295MPa i den behandlade och 400MPa i den obehandlade simuleringarna, till 160MPa efter optimeringsalgoritmen. Det blev tydligt att vinkeln på cheilectomin samt orienteringen av implantatet har en avgörande betydelse för det postoperativa resultatet. Dock skulle formen på cheilectomin liksom designen av implantatet behöva revideras i framtida utformningar, då det nuvarande konceptet inte lyckades att ge leden en ny ledyta. Vidareutveckling av de modeller som utvecklats i avhandlingen rekommenderas, samt att validera resultaten med annan kliniska data.