We introduce a new way to accurately segment the 3D femur from pelvic CT scans. The femur is a difficult target for segmentation due to its proximity to the acetabulum, irregular shape and the varying thickness of its hardened outer shell. Atypical bone morphologies, such as the ones present in hips suffering from Femoral Acetabular Impingements (FAIs) can also provide additional challenges to segmentation. We overcome these difficulties by (a) dividing the femur into the femur head and body regions (b) analysis of the femur-head and neighbouring acetabulum’s composition (c) segmentations with two levels of detail – rough and fine contours. Segmentations of the CT volume are performed iteratively, on a slice-by-slice basis and contours are extracted using the morphological snake algorithm. Our methodology was designed to require little initialization from the user and to deftly handle the large variation in femur shapes, most notably from deformations attributed to cam-type FAIs. Our efforts are to provide physicians with a new tool that creates patient-specific and high-quality 3D femur models while requiring much less time and effort. We tested our methodology on a database of 20 CT volumes acquired at the Ottawa General Hospital during a study into FAIs. We selected 6 CT scans from the database, for a total of 12 femurs, considering wide inter-patient variations. Of the 6 patients, 4 had unilateral cam-type FAIs, 1 had a bilateral cam-type FAI and the last was from a control group. The femurs segmented with our method achieved an average volume overlap error of 2.71 ± 0.44% and an average symmetric surface distance of 0.28 ± 0.04 mm compared against the same, manually segmented femurs. These results are better than all comparable literature and accurate enough to be used to in the creation of patient-specific 3D models.

Femoro-Acetabular Impingement (FAI) is a hip joint disease which affects and impairs the range of hip motion during performing activities of daily living, jogging, walking, or climbing stairs due to the bony abnormalities of the joint. Ballet dancers and athletes (e.g. gymnasts and hockey players) put their hips at the risk of FAI by extremely moving the hip mainly by excessively rotating the joint. In this research, we introduce a visualization system which helps surgeons to analyze the range of hip motions as well as to have a better communication with patients. These goals are achieved by presenting three dimensional (3D) visualizations of motion envelope by examining the maximum possible rotation of the digital hip bones. Our computer simulation system estimates, analyzes and visualizes the maximum hip range of motion (ROM) for the constructed 3D bone models that are extracted from Magnetic Resonance Images (MRI) after segmenting the bones. These tasks are accomplished by first calculating Hip Joint Center (HJC) which is center of rotation of femoral head on the 3D segmented MRI models followed by simulating hip motions with examining impingement between the femur and the acetabulum using our collision detection system. In our collision detection system, surfaces of femoral head and acetabulum bones are sampled in the spherical coordinates based on rasterization and interpolation. Then, the distance between the femoral head and acetabulum are computed to prevent impingement between them. The maximum motion degree of femur bone within depression of acetabulum in every direction during the digital simulation shows the ROMs of the inputted MRI of the hip joint. Six primary plane motions (flexion/extension, abduction/adduction and internal/external rotation) as well as various combinations of these motions (maximum rotation of the hip between every two rotational movements) and successive movements (maximum rotational movement of the hip per another rotational movement) are simulated and analyzed along with 3D visualization of estimated range of these motions. Generally, the ROM differs by some factors such as age, gender, ethnicity, and geographic location. For instance, newborns up to age two have considerably greater motion in hip flexion and hip abduction than adults. Our system by 3D visualization of motion envelope will provide a platform to understand quicker and better the effect of bony morphology of the hip joint on the possible ROM. We also examine the long-standing question about moving center of rotation related to ROM. We found out the ROM becomes bigger especially when the center moves outward to the direction of acetabulum axis. This thesis does not consider the effect of muscle and other surrounding connective tissue on the hip ROM since they can be altered significantly by physical training to show the potential of maximum ROM. For example a ballerina has a bigger ROM leading a bigger motion envelope compared with non-dancers. Hence we visualize the range of joint motions and their envelopes that are obtained from the osseous anatomy of the hip joint. The osseous anatomy of the joint is the most fundamental and permanent factor of ROM which indicates the maximum motion that the joint can achieve if the muscle and other connective tissues are perfectly trained.

Title: The evaluation of surgical treatment of the hip in the diagnosis of femor- acetabular impingement syndrome. Objectives: The main objective of this work is to evaluate the effect of the surgery of the hip in diagnosis of femor-acetabular hip impingement. Methods: In our work we have cooperated with 103 patients who have been operated on hip with the diagnosis of femor-acetabular hip impingement (FAI). We used standardized questionnaires of WOMAC and NAHS, which assesses functional self- care, limitations in motion and painfulness. Patients completed questionnaires twice. For the first time before surgery and second time at least one year after the surgery. The specimens of questionnaire are attached in the Annex. Results: We found out that postoperative condition is significantly different from the preoperative state in terms of improved self-care, increased range of motion and reduction of painfulness. Keywords: Femor-acetabular impingement, hip surgery, WOMAC, NAHS

Femoral acetabular impingement (FAI) is a bony hip condition that often results in tears to the acetabular labrum. Patients with FAI experience pain, decreased function, and quality of life. FAI and its’ sequela are treated definitively with hip arthroscopy. Hip arthroscopy is being performed with increasing frequency, and while most patients respond favorably, a subset of 10-20% of patients have suboptimal outcomes. Previous research suggests that mental status may be a primary driver in the way patients with FAI respond to and feel pain. Measures of mental status include the presence of mood disorders and psychosocial patient reported outcomes (PROs). Psychosocial constructs that have yet to be examined in patients with FAI include self-efficacy, kinesophobia, and pain catastrophizing. The Pain Self-Efficacy Questionnaire (PSEQ) gauges an individual’s confidence, or self-efficacy, in their ability to complete tasks despite their current pain. Previous research has established that a patient’s self-efficacy is an important determinant of long-term success following orthopedic surgery. Kinesophobia, measured via the Tampa Scale for Kinesiophobia (TSK), is a measure of movement-related fear. In contrast to self-efficacy, fear of movement has been identified as a predictor of early success following orthopedic surgery. Lastly, pain catastrophizing is a set of maladaptive behaviors including ruminating on pain, feeling helpless to overcome painful situations, and magnifying the circumstances surrounding the painful experience. Catastrophizing behaviors, measured via the Pain Catastrophizing Scale (PCS), have been repeatedly linked to increased pain and decreased functionality in a variety of orthopedic populations. To date, the relationship between these psychosocial variables and pain has not been examined in patients with FAI. The primary aim of this dissertation was to evaluate the role of psychosocial factors on pre and postoperative pain in patients with FAI undergoing hip arthroscopy. To accomplish this aim we performed a series of three studies. The first study was a retrospective chart review to determine the prevalence of mental health disorders and compare preoperative clinical presentation between patients with and without mental health disorders. The second was a cross-sectional study designed to determine if any psychosocial variables could predict preoperative hip pain. The final study utilized a longitudinal, cohort design. Patients were tested preoperatively and at 12-weeks postoperative. The primary outcomes measured were self-efficacy, kinesiophobia, pain catastrophizing, and hip pain at rest and during activity measured via a visual analog scale (VAS). The purpose of this study was to determine the effect of preoperative psychosocial variables on postoperative pain, and to determine if these variables were predictive of persistent postoperative pain three months following hip arthroscopy. Based on the results from these studies we can conclude the following: 1) Mental health disorders are more common in patients with FAI than other orthopedic populations, and self-reported pain and function are worse in this subset of patients, but neither symptom chronicity nor the severity of joint deformity differs; 2) Low self-efficacy is predictive of worse preoperative pain in patients with FAI; and 3) Patients with high preoperative pain catastrophizing or low self-efficacy are more likely to have increased postoperative pain. Low preoperative self-efficacy is predictive of persistent hip pain during activity three months following hip arthroscopy, while low self-efficacy and mental health disorders are predictive of persistent hip pain at rest. Future studies are necessary to develop and implement interventions targeting low self-efficacy and elevated catastrophizing in patients undergoing hip arthroscopy to improve patient outcomes for this high-risk group.

Polyethylene wear and micromotion of the implant play an important role in multifactorial etiology of osteolysis leading to aseptic loosening of the acetabular components. Despite excellent results in primary total hip arthoplasty in a 10-15 year perspective there are still unsolved problems. The weakest link is the longevity of the actabular component. Young and active patients have a clearly worse outcome than older patients. Consequences of polyehtylene wear and ways to reduce wear have therefore been in focus during recent years. Radiostereometry (RSA) is the golden standard in measuring in vivo micromotions. In 4 clinical studies including 332 patients we used therefore RSA to record the efficacy of fixation of cemented and uncemented cups. The amount of wear of old and newly designed polyethylenes (PE) was related to cup stability and radiological and clinical measures of outcome. This study showed that cementless cups inserted with pressfit technique do not need additional augmentation. Screws and pegs increase the risk for radiolucencies and osteolystic lesions but are helpful tools in cases where primary stability is jeopardized. In the second decade clinically silent osteolysis is common for the porous coated Harris Galante cup with unsealed screw holes. The locking mechanism of the PE liner in this cup is unsatisfactory and an increase of liner dissociations is expected. EtO sterilized PE displayed high in vivo wear and we do not recommend its continued use but close monitoring of patients with earlier inserted EtO sterilized implants. The substantially reduced wear in cemented highly cross-linked PE cups without any negative in vivo tradeoffs might have a substantial impact on choice of material and operating technique in the near future. However, we still recommend its restrained use in controlled series until longer follow-up data is available. Nevertheless, the short term in vivo results of modern highly cross-linked PE look promising and ight improve the outcome of cemented and uncemented hip arthroplasties by reducing complication and revisions.

No description available.

No description available.

Every year, about 1 million patients worldwide and 16000 patients in Sweden undergo total hip arthroplasty (THA). This surgical intervention is considered a successful, safe and cost-effective procedure to regain pain-free mobility and restore hip joint function in patients suffering from severe hip joint disease or trauma. Besides relieving the pain, restoration of biomechanical forces around the hip with appropriate femoral offset (FO), leg length and proper component position and orientation are important goals. The radiographic preoperative planning and postoperative evaluation of these parameters require good validity, interobserver reliability and intraobserver reproducibility. It remains controversial as to how much postoperative leg length discrepancy (LLD) and FO change are acceptable. Generally, lengthening of the operated leg ≥ 10mm and FO reduction of the operated hip > 5mm should be avoided by using preoperative radiological templating and intraoperative measurement methods. There is no consensus on the association between LLD and FO and outcome after THA. The aims of this thesis were to: 1. To determine the influence of non-corrected LLD after THA on patients’ reported hip function and quality of life (QoL). 2. To study the association of global FO changes after THA with patients’ reported hip function, QoL and abductor muscle strength. 3. To evaluate the concurrent validity of the Sundsvall method of measuring postoperative global FO by comparing it to a standard method and to evaluate the interobserver reliability and intraobserver reproducibility of measurement of postoperative global FO, LLD and acetabular cup inclination and anteversion. 4. To analyse the postoperative radiographs of THA patients with leg lengthening and FO reduction to determine whether the problem is located in the stem, cup or both. Study I: A prospective cohort study of 174 patients with unilateral osteoarthritis (OA), comparing patients with lengthening ≥ 10mm, restoration (between 9 mm lengthening and 5 mm shortening) or shortening > 5 mm of the operated leg after THA. Follow up was 12–15 months. We found that a LLD of up to 20 mm did not influence the functional outcome (WOMAC) or QoL (EQ-5D). However, the lengthening group showed less improvement in WOMAC and more use of a shoe lift. Study II: A prospective cohort study of 222 patients with unilateral hip OA, comparing patients with decreased global FO (> 5 mm reduction), restored FO (within 5 mm restoration), and increased FO (> 5 mm increment) after THA. Follow up was was 12–15 months. The unadjusted results showed that the decreased FO group had a worse WOMAC index, less abductor muscle strength, and more use of walking aids. When these results were adjusted for possible confounding factors, only global FO reduction was statistically significantly associated with reduced abductor muscle strength. The incidence of residual hip pain and analgesics use was similar in the 3 groups. Study III: A prospective cohort study of 90 patients with primary unilateral OA treated with THA. Global FO using the Sundsvall method, global FO (standard method), LLD, acetabular cup inclination and anteversion were measured on postoperative radiographs. The interobserver reliability and intraobserver reproducibility were tested using three independent observers. We found that the Sundsvall method is as reliable as the standard method and the evaluated radiographic measurement methods have the required validity and reliability to be used in clinical practice. Study IV: A prospective cohort study of 174 patients with unilateral primary OA treated with THA. LLD and global FO were measured on postoperative radiographs. Patients with lengthening of the operated leg ≥ 10mm (n=41) and patients with reduction of global FO > 5mm (n=58) were further studied to investigate the amount of lengthening and global FO reduction that took place in the stem and in the cup compared with the contralateral side. The interobserver reliability and intraobserver reproducibility were tested using two independent observers. We found that post-THA lengthening of the operated leg ≥ 10mm was mainly caused by improper placement of the femoral stem, whereas a decrease of global FO > 5 was caused by improper placement of both acetabular and femoral components. The radiological measurement methods used showed substantial to excellent interobserver reliability and intraobserver reproducibility and are therefore clinically useful. The main conclusions of this thesis are: LLD up to 20 mm and reduced global FO more than 5 mm did not influence the functional outcome or quality of life at 12–15 months postoperatively. Lengthening ≥ 10mm was associated with increased use of a shoe lift. A reduction of global FO more than 5 mm compared to the contralateral hip was associated with weaker hip abductor muscles and more use of walking aids. Therefore both should be avoided. The radiographic measurement methods of LLD, global FO, cup inclination and anteversion have the required validity and reliability to be used in clinical practice. Lengthening of the operated leg is mainly caused by improper femoral stem positioning while global FO reduction results from improper positioning of both acetabular and femoral components. Surgeons should be aware of these operative pitfalls in order to minimize component malpositioning. / Varje år opereras ungefär 1 miljon patienter runt om i världen och 16000 patienter i Sverige med en total höftledsprotes (THA). Operation med höftledsprotes anses vara enav de mest framgångsrika, säkra och kostnadseffektiva kirurgiska åtgärderna med syfte att för att återställa livskvalité. Målet är att smärtlindra och återställa rörligheten i dendestruerade höftleden vid artros, reumatisk destruktion eller men efter exempelvis Perthes sjukdom. Vid operation med THA är det viktigt att återställa de biomekaniskakrafterna runt höftleden med en adekvat så kallad femoral offset (FO), postoperativ benlängdsskillnad (BLS) och ett tillfredsställande komponentläge. Den preoperativaplaneringen och den postoperativa bedömning av dessa parametrar kräver god tillförlitlighet, det vill säga validitet och reproducerbarhet både mellan olika bedömareoch vid upprepade mätningar av samma bedömare. Det är fortfarande inte klarlagt hur mycket postoperativ förändring i FO och BLS som är acceptabla. I dagsläget är detacceptabelt om den postoperativa benförlängningen understiger 1 cm och förändringen i FO är under 5 mm. Det finns ingen konsensus huruvida det föreligger ett sambandmellan BLS, FO och den patientrapporterade höftfunktionen och livskvalitén efter THA. Syftet med denna avhandling var: 1. Att studera effekten av icke-korrigerad BLS efter THA på den patientrapporterade höftfunktionen och livskvalitén. 2. Att studera effekten av förändringen i FO efter THA på den patientrapporterade höftfunktion, livskvalitén och muskelstyrka i abduktion. 3. Att utvärdera validitet och reliabilitet av en så kallad global FO genom att jämföra den med den gällande standard metoden samt studera tillförlitlighet av de radiologiskamätningar av postoperativa BLS, FO, cup inklination och anteversion efter THA. 4. Att radiologiskt undersöka i vilken av komponenterna (stam eller cup) somförändringen i FO och BLS verkar vara förlagd. Studie I: En prospektiv kohortstudie med 174 patienter som behandlats med THA för en primär unilateral koxartros. Patienterna delades in i tre grupper; de som fått en BLSförlängning över 10mm, återställning (mellan 9mm förlängning och 5mm förkortning) eller förkortning >5mm av det opererande benet efter THA. Uppföljning gjordes 12-15månader postoperativt. Vi fann att BLS upp till 20mm påverkade inte höftfunktion (WOMAC) och livskvalité (EQ-5D), men den förlängda gruppen visade en mindreförbättring i WOMAC och rapporterade en mer frekvent användning av skoinlägg. Studie II: En prospektiv kohortstudie med 222 patienter som behandlats med THA för en primär unilateral koxartros. Patienterna delades in i tre grupper; de patienter medförminskad FO (> 5mm minskning), återställd FO (inom 5mm) eller ökad FO (>5mm ökning). Uppföljning genomfördes efter 1 år med WOMAC, styrkemätning av höftensabduktorer och en frågeformulär. En minskad FO var associerade med en minskad styrka i höftens abduktorer. Det var ingen skillnad mellan grupperna gällandekvarstående höftsmärta och användning av analgetika. Studie III: En prospektiv kohortstudie med 90 patienter som behandlats med THA på grund av primär unilateral koxartros. På de postoperativa röntgenbilderna uppmättesglobala FO (Sundsvalls metodologi), globala FO (standard metod), BLS, cup inklination och anteversion. Reliabilitet och reproducerbarhet bedömdes mellan treoberoende observatörer. Vi fann att global FO (enligt Sundsvalls metodologi) är lika tillförlitlig som den nuvarande standardmetoden och de utvärderade radiologiskamätmetoderna har hög validitet och reliabilitet och kan således användas i klinisk praxis. Studie IV: En prospektiv kohortstudie med 174 patienter som behandlats med en THA för en primär unilateral koxartros. På de postoperativa röntgenbilderna uppmättes BLSoch globala FO. Patienter med förlängning ≥ 10mm (n=41) och patienter med minskning av globala FO >5mm (n=58) studerades for att mäta förlängning ochglobala FO minskning som sitter i stammen eller i cup jämfört med kontralaterala sidan. Reliabilitet och reproducerbarhet bedömdes av två oberoende observatörer. Vifann att en BLS över 10mm sitter framför allt i stamkomponenten i lårbenet medan en minskning i FO över 5 mm sitter i båda stam och cup. De radiologiska mätmetodernahar hög reliabilitet och reproducerbarhet och kan således användas i klinisk praxis. De viktigaste slutsatserna i denna avhandling är: 1. BLS med en förlängning upp till 20 mm och en minskning av globala FO mer än 5 mm påverkar inte patientrapporterad höftfunktion eller livskvalitet 1 år postoperativt. 2. BLS med en förlängning mer än 9 mm var associerad med mer användning av skoinlägg. En minskad FO med mer än 5 mm jämfört med den icke opererade höftenvar associerad med en sämre muskelstyrka i abduktion och ökat användning av gånghjälpmedel. 3. De radiologiska mätmetoderna av BLS, FO, acetabulära komponentens inklination och anteversion har hög validitet och reliabilitet, vilket kan användas i klinisk praxis. 4. En förlängning av det opererade benet orsakas främst av en positioneringen av stamkomponenten i lårbenet medan förlust av FO beror på otillfredsställande placeringav både stam och den acetabulära komponenten. Kirurger bör vara medveten om dessa operativa fallgropar för att optimera det kirurgiska resultatet.

The most common cause for revision total hip replacement surgey is aseptic loosening of the acetabular component. This thesis explores the effect of three techniques to improve the depth and quality of cemented acetabular component fixation in primary total hip replacement. This may have beneficial effects on the longevity of cemented acetabular components and reduce the rate of revision surgery for aseptic loosening. Aims: 1. Determine the effect of the rim cutter on cement pressure during cup insertion. 2. Examine the effect of the rim cutter on cement penetration distance. 3. Evaluate the effect of bone grafting of the acetabular notch. 4. Determine the effect of iliac suction during cement pressurisation. 5. Compare the behaviour of bone cement with Play Dough. Materials and Methods: 1. Sawbones hemi pelvis models were fitted with pressure transducers at the rim and apex of the acetabulum. Peak pressure was measured upon insertion of cups with different flange sizes and when the acetabulum was prepared with the rim cutter. 2. Foam cavities were used to measure the depth of cement penetration when the same cups and rim cutter were used. 3. Hemi pelvis models were modified to simulate bone grafting of the acetabular notch. Again, pressure sensors were mounted at the apex and rim of the acetabulum. Intra-acetabular cement pressure was compared with native acetabulae. 4. A back bleeding model of the acetabulum was fitted with a suction catheter. The effect on cement penetration into cancellous bone was measured compared with no suction. 5. Play Dough pressurisation and penetration into hemi pelvises and foam was compared to bone cement. Results: 1. Significant increase in peak apex and rim pressures when flanged cup inserted into an acetabulum prepared with the rim cutter compared with both flanged and unflanged cups alone. 2. Significant increase in cement penetration at the rim of the acetabulum when rim cutter used and flanged cup inserted when compared with flanged and unflanged cups alone. 3. Significant increase in intra-acetabular pressure when cement pressurised in presence of simulated acetabular notch bone grafting compared with normal acetabulae. 4. Significant increase in cement penetration distance when suction used compared with no suction. 5. Significant differences in the flow characteristics between bone cement and Play Dough. Conclusion: The authors recommend preparation of the acetabular rim with the rim cutter and bone grafting of the acetabular notch to improve the depth and uniformity of the cement mantle in cemented primary THA. Play Dough at room temperature is not a suitable substitute for bone cement in in-vitro cementing studies.

Ce travail porte sur l’étude du comportement biomécanique d’un modèle cadavérique et d’un modèle in vitro de l’arthroplastie totale de hanche. Nous avons cherché à mettre en relief et à étudier des paramètres qui pouvaient nous permettre de disposer d’une méthode d’analyse objective de la stabilité de l’implant acétabulaire. La première partie décrit le contexte de l'étude. Nous avons insisté sur les différentes méthodes d’analyses qui permettent d’analyser la stabilité d’un implant osseux. En effet, malgré l’utilisation quotidienne des implants, le taux d’échec d’ostéointégration reste élevé. Ces échecs s’accompagnent d’une morbidité importante et d’un surcout notable. Parmi les causes d’échec identifiées, le descellement aseptique de la cupule acétabulaire dans l’arthroplastie de hanche peut être lié à un défaut de stabilité primaire, non obtenu lors de l’intervention chirurgicale. Il a été montré que le descellement de la cupule acétabulaire pouvait résulter d'une faible stabilité primaire entre la cupule et l'os l'entourant. Les chirurgiens qui pratiquent l’arthroplastie de hanche évaluent de manière empirique la stabilité obtenue ou non de l’implant acétabulaire en écoutant le son produit lorsqu'ils impactent la cupule ou à leur ressenti en la manipulant. Une méthode d'estimation de la stabilité primaire pourrait permettre au chirurgien orthopédique de mieux appréhender la stabilité des implants qu’il pose au bloc opératoire. L'objet principal de ce travail de thèse était ainsi d'étudier les signaux d'impacts sur le cotyle prothétique. Dans un premier temps, nous avons réalisé une étude de l'insertion de la cupule par impacts sur un modèle cadavérique (sujets anatomiques de l’école de chirurgie du fer à moulin) dans des conditions proches de celle de l'opération en clinique. Une corrélation a été trouvée entre le moment d'impact et la stabilité (R2=0.69). Cette étude expérimentale a ainsi montré le potentiel de la méthode de traitement des signaux d'impact dans la prédiction de la stabilité primaire de la cupule acétabulaire. Mais nous avons observé des modifications entre les signaux obtenus sur les différents sujets. Nous avons posé comme hypothèse que ces modifications étaient liées à la variation des tissus mous entre chaque sujet. Le troisième volet de cette thèse a donc porté sur l’analyse du comportement biomécanique de notre modèle en présence d’une quantité plus ou moins importante de muscle.Nous avons utilisé à nouveau le modèle in vitro que nous avions développé et avons ajouté dans le système d’impaction des tranches de poitrine de dinde d’épaisseur variable. Le but de cette seconde étude était d’intégrer le paramètre lié à l’existence d’une épaisseur variable de tissus mous dans l'interaction dynamique entre le marteau, l'ancillaire (et la cupule) et le tissu osseux lors de l'insertion. La valeur de la moyenne et de l’écart-type de l'indicateur Im obtenues pour tous les échantillons et toutes les configurations pour une valeur d’épaisseur des tissus mous égale à 10 mm (respectivement 30 mm) étaient égales à 0,592 ± 0,141 (respectivement 0,552 ± 0,139). L’analyse statistique a montré qu'il n'y avait pas eu d'effet significatif de la valeur de l’épaisseur des tissus mous sur les valeurs de l'indicateur Im (F = 3,16; p = 0,08). Malgré les limitations évidentes d’une étude in vitro sur un modèle partiel d’arthroplastie totale de hanche, ces résultats, ainsi que les résultats précédents obtenus sur les sujets anatomiques, montrent la faisabilité du développement d'un dispositif médical dédié à l'estimation de la stabilité de l'implant acétabulaire et qui pourrait être utilisé comme système d'aide à la décision par le chirurgien orthopédique. / Abstract:This work studies the biomechanical behavior of a cadaveric model and an in vitro model of total hip arthroplasty. We sought to highlight and study parameters that could allow us to have a method of objective analysis of the stability of the acetabular cup implant.The first part describes the context of the study. We have emphasized the different methods of analysis that make it possible to analyse the stability of a bone implant. Indeed, despite the daily use of implants, the failure rate of osseointegration remains high and failures still happen due to inadequate mechanical behavior of the prosthesis.Among the identified causes of failure, aseptic loosening of the acetabular cup after hip arthroplasty may be related to a primary defect in stability, not achieved during the surgical procedure. It has been shown that loosening of the acetabular cup may result from poor primary stability between the prosthetic cup and the surrounding bone.A method of estimating primary stability could allow the orthopaedic surgeon to better control the stability of the implants he poses in the operating room.The main purpose of this thesis work was to study the impact signals on the prosthetic acetabulum.Firstly, we carried out a study of the insertion of the cup by impacts on a cadaveric model. A correlation was found between impact time and stability (R2 = 0.69). This experimental study has thus shown the potential of the impact signal processing method in predicting the primary stability of the acetabular cup. But we observed changes between the signals obtained on the different subjects. We hypothesized that these changes were related to soft tissue variation between subjects.The third part of this thesis focused on analysing the biomechanical behavior of our model in the presence of soft tissues.We used again the in vitro model that we had developed and added in the impaction system turkey slices of varying thickness.The purpose of this second study was to integrate the parameter related to the existence of a variable thickness of soft tissues in the dynamic interaction between the hammer, the ancillary (and the cup) and the bone tissue during the insertion. The mean and standard deviation of the Im indicator obtained for all samples and configurations at a soft tissue thickness value of 10 mm (30 mm) was 0.592 ± 0.141, (respectively 0.552 ± 0.139). Statistical analysis showed that there was no significant effect of the value of soft tissue thickness on the values of the Im indicator (F = 3.16, p = 0.08). Despite the obvious limitations of an in vitro study on a partial model of total hip arthroplasty, these results, as well as the previous results obtained on anatomical subjects, show the feasibility of developing a medical device dedicated to estimating the stability of the acetabular implant and which could be used as a decision support system by the orthopaedic surgeons.