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Contexto: O objetivo do estudo foi avaliar a reprodutibilidade intra e interobservador da versão acetabular e femoral da prótese total de quadril. Materiais e métodos: estudo prospectivo incluindo 101 indivíduos submetidos a prótese total de quadril, sendo 114 quadris desde 2008, com imagens de tomografia computadorizada incluindo os componentes acetabular e femoral da prótese e os côndilos femorais. Resultados: Para avaliação intraobservador o coeficiente de correlação interclasse foi para o observador A de 0.99 para versão acetabular e femoral com intervalo de confian- ça (IC) de 0.98-1.00, para o observador B de 0.98 para versão acetabular (IC de 0.97- 0.99) e de 0.88 para versão femoral (IC de 0.83-0.92), para o observador C de 0.98 para versão acetabular (IC de 0.97-0,99) e de 0.83 para versão femoral (IC de 0.76-0.88). Para avaliação interobservador o coeficiente de correlação interclasse foi calculado com as medidas da primeira leitura de cada observador e em seguida da segunda leitura, sendo a primeira leitura da versão acetabular de 0.99 (IC de 0.98-1.00), a segunda leitura da versão acetabular de 0.99 (IC de 0.98-1.00), a primeira leitura da versão femoral de 0.99 (IC de 0.98-1.00), a segunda leitura da versão femoral de 0.96 (IC de 0.94-0.97). Conclusão: Com os resultados obtidos, podemos concluir que as medidas tomográficas de versão acetabular possuem excelente reprodutibilidade tanto inter quanto intraobservador, as medidas de femoral possuem excelente reprodutibilidade interobservador e de boa a excelente reprodutibilidade intraobservador. / Context: The objective of the study was to evaluate the reproducibility intra e interobserver of acetabular and femoral version after total hip arthroplasty. Materials and methods: prospective studying including 101 individuals after total hip arthroplasty, 114 hips since 2008, with computed tomography images including the components of acetabular and femoral prothesis and the femoral condyle. Results: intra-observer coefficient of interclass correlation was 0.99 for observer A for acetabular and femoral version (IC of 0.98-1.00), for B 0.98 for acetabular version (IC of 0.97-0.99) and 0.88 for femoral version (IC of 0.83-0.92), for C 0.98 for acetabular version (IC of 0.97-0.99) and 0.83 for femoral version (IC of 0.76-0.88). For inter-observer evaluation, the interclass correlation coefficient was calculated with the measurements of the first reading of each observer and the second reading, the first reading of the acetabular version was 0.99 (IC of 0.98-1.00), the second reading of the acetabular version was 0.99 (CI 0.98-1.00), the first reading of the femoral version was 0.99 (CI of 0.98-1.00), the second reading of the femoral version was 0.96 (CI of 0.94- 0.97). Conclusion: With the results obtained, we can conclude that the tomographic measurements of acetabular version have excellent inter- and intraobserver reproducibility, femoral measurements have excellent interobserver reproducibility and good to excellent intraobserver reproducibility.

Yes / We read with interest the recent article by Yun et al. [1] comparing acetabular and hip measurements across pelvis, hip and lumbar spine radiographs. The authors assert that lumbar radiographs can be utilised in place of routine pelvis radiographs for these measurements. The example lumbar spine radiograph (figure 2) appears to be an abdominal image, with a contrast urogram. Indeed, standard texts [2,3] confirm that the anteroposterior lumbar spine radiograph should not include any coverage of the hips as appropriate collimation should limit the anatomy to T12 superiorly, lower sacrum inferiorly and the sacroiliac joints laterally, which would exclude the hip joints. Thus assessing any hip measurements on an appropriately collimated lumbar spine radiograph should not be possible. This is further compounded by the description of the centring point within their study (iliac crest), which varies from the internationally recognised standard of lower costal margin/L3 [2,3].

Periacetabular osteolysis is a significant complication following total hip replacement surgery. It is believed to be caused by wear debris and high fluid pressures within the joint capsule. To investigate the mechanisms by which high fluid pressures are generated in total hip replacement, a physical model of the hip joint was constructed, the Acetabular Pressure Transmission Rig (APTR). An aluminium chamber held the bone analogue, a polyurethane hemisphere with a 52mm acetabular cavity, and the prosthetic components, a 28mm femoral head and various uncemented cups, were inserted without press-fit to simulate cup loosening. A synovial fluid analogue was introduced into the chamber through an elevated reservoir. Rigid transmission tubes conducted fluid pressures from the cup-cavity interface to external transducers. The APTR was loaded under various conditions and the pressures produced by the loading regimes were analysed. Pressures over 35kPa, previously shown by other groups to cause osteolysis, were measured within the APTR, reaching a maximum of 131.3kPa measured at the pole of the cup. Changes in load application led to pressure changes within the APTR, with higher loading frequency and magnitude leading to higher median pressure amplitudes. The presence of different component features, such as screw holes in the metal shell, was also shown to affect periacetabular pressures. Tests with a fibrous rim interposed between the prosthetic cup and the test cavity showed an 88% reduction in periacetabular pressures, as the increased rim interference between cup and cavity prevented fluid ingress behind the cup. A larger initial separation between the loading head and the acetabular cup caused a significant increase in measured pressures, with a 0.15mm increase in head-cup separation producing a 53% increase in pressures measured at the pole of the cup. Pressure differentials between different transducer sites indicated the ability for fluid flow behind the cup, which can be related in vivo to the movement of particulate debris to periacetabular bone. The APTR was able to measure clinically significant pressures and to analyse the effects of modifying component and loading characteristics with currently available prosthetic components. This makes the rig useful in a clinical context, as it has been shown to be capable of testing a broad range of component types under a wide range of conditions. Its use will ensure new prostheses and fixation modes can be designed in such a way as to eliminate the damaging fluid pressures currently observed in artificial hip joint replacements.

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.

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.

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.

Age-at-death estimation is a key component of creating a biological profile in forensic and bioarchaeological contexts, and the development of methods that utilize different skeletal elements or observe traits in a new manner are an important part of progress in the study of forensic anthropology. Use of the acetabulum for identifying age-at-death is among new methods being developed, and the recently published method by Calce (2012) was the focus of the present study. The present author analyzed a sample of 489 modern American individuals drawn from the William M. Bass Donated Skeletal Collection housed at the University of Tennessee and assigned each individual to a phase described by Calce (2012). The results of the present study show that use of this method correctly classified age-at-death 62.2% of the time. The performance of this method is low compared to the results of the initial study where Calce (2012) found the method to be 81% accurate. This suggests that the acetabulum is not as beneficial as an age-at-death indicator as previously considered, and that more research on the utility of the acetabulum as an age indicator is required.

L'arthroplastie totale de hanche est une des interventions le plus pratiquées en chirurgie orthopédique. Malgré un taux de réussite élevé, cette chirurgie présente des limites, liées aux complications possibles, dont la luxation reste la principale cause de reprise chirurgicale. Les causes de l'instabilité prothétique ne sont pas entièrement connus. La relation entre la position de la cupule acétabulaire et l'instabilité n'est pas consensuelle, dans la littérature. Le développement de la navigation chirurgicale a le mérite de mettre en évidence ces limites. L'objectif de cette thèse est de proposer un positionnement optimal de la cupule acétabulaire, pour diminuer le risque de luxation. Deux études différentes ont été réalisé, la première étant une analyse de l'orientation anatomique de 150 sujets sains et la deuxième, une étude comparative cas-temoin analysant le risque de luxation en fonction de l'orientation acétabulaire. La première étude à retrouvé une très grande variabilité d'orientation acétabulaire anatomique. La deuxième étude à permis d'identifier un algorithme de calcul du risque de luxation en fonction du débord prothétique par rapport à l'orientation de l'acetabulum (la difference entre l'orientation de l'acetabulum et celle de la cupule prothétique). Cette recherche montre que le positionnement prothétique acétabulaire le plus proche de l'orientation de l'acetabulum diminue le risque de luxation. Ce résultat original pourra être utilisé par les systèmes de navigation pour améliorer la précision de la chirurgie conventionnelle. / The hip arthroplasty is one of the most successful interventions in orthopedics. Despite its good results, there are still some important issues to clarify. One of the most disturbing complication is dislocation. It represents the number one cause of failure. Its causes are not fully understood, especially the relationship between the orientation of the acetabular cup and dislocation. There is no generally accepted optimal cup orientation, in the literature. Computer navigation technologies contributed to recognize these limitations in the field of hip arthroplasty. The thesis purpose is to identify the optimal position of the ace tabular cup, in relation withe the risk of dislocation. Two studies were conducted in parallel: firstly, the analysis of the normal anatomical acetabular orientation on 150 healthy subjects and secondly, a comparative case control study, analyzing the relationship between the risk of dislocation and the cup orientation. The first study found a very important variability in the anatomical orientation of the acetabulum. The second one allowed to describe and quantify the relationship between the risk of dislocation and the ace tabular cup overhang (the difference between the orientation of the acetabulum and the cup orientation). This research shows that cup positioning closest to the acetabulum orientation, diminishes the dislocation risk. This original data could be used by the navigation systems to increase the cup placement accuracy.