Academic literature on the topic 'Proximal femur geometry'
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Journal articles on the topic "Proximal femur geometry"
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Cornelissen, Andries Johannes, Nando Ferreira, Marilize Cornelle Burger, and Jacobus Daniel Jordaan. "Proximal femur anatomy-implant geometry discrepancies." SICOT-J 8 (2022): 5. http://dx.doi.org/10.1051/sicotj/2022004.
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Objectives: Due to ongoing concern about femur anatomy-implant mismatches, this cross-sectional study aimed to create a geometric femur profile and used it to identify and quantify possible mismatches between femur anatomy and cephalomedullary nail dimensions. The work further aimed to assess whether patient demographics affect anatomy-implant coherence. Methods: One hundred skeletally mature complete femur computer tomography (CT) scans were collected and exported to software enabling landmark placement and measures with multiplanar reconstruction techniques. Results: Clinically relevant anatomy-implant discrepancies included the femur neck and shaft axis offset 6.1 ± 1.7 mm (95% CI [5.7–6.4]), femur radius of curvature 1.2 ± 0.3 m (95% CI [1.1–1.2]), femur anteversion 18.8 ± 9.2 (95% CI [16.9–20.6]). The implants reviewed in this study did not compensate for the femur neck and shaft axis offset and had a larger radius of curvature than the studied population. Clinically significant demographic geometry differences were not identified. Conclusion: There were discrepancies between femur anatomy and cephalomedullary nail implant design; however, no clinically significant femur feature inconsistency was identified among the demographic subgroups. Due to the identified anatomy-implant discrepancies, including the femur neck and shaft axis offset, we suggest that these measurements be considered for future implant design and surgical technique.
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Vander Sloten, J., and G. van der Perre. "The Influence of Geometrical Distortions of Three-Dimensional Finite Elements, Used to Model Proximal Femoral Bone." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 209, no. 1 (March 1995): 31–36. http://dx.doi.org/10.1243/pime_proc_1995_209_314_02.
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A realistic three-dimensional finite element model of the proximal femur requires the use of irregularly shaped elements to represent this geometry, unless the geometry is considerably simplified. The authors have investigated the influence of different types of element distortions upon the accuracy of two stresses which are relevant in the proximal femur: the bending stress and the tangential (hoop) stress. While most angular and geometric distortions did not influence the bending stress significantly, the position of the middle node on the edge of a quadratic element was very critical, as were some types of element skewness. The hoop stresses can only be calculated accurately if the geometry is modelled as well as possible by a cylinder, and not by a cone.
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Trombetti, Andrea, Laura Richert, François R. Herrmann, Thierry Chevalley, Jean-Daniel Graf, and René Rizzoli. "Selective Determinants of Low Bone Mineral Mass in Adult Women with Anorexia Nervosa." International Journal of Endocrinology 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/897193.
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We investigated the relative effect of amenorrhea and insulin-like growth factor-I (sIGF-I) levels on cancellous and cortical bone density and size. We investigated 66 adult women with anorexia nervosa. Lumbar spine and proximal femur bone mineral density was measured by DXA. We calculated bone mineral apparent density. Structural geometry of the spine and the hip was determined from DXA images. Weight and BMI, but not height, as well as bone mineral content and density, but not area and geometry parameters, were lower in patients with anorexia nervosa as compared with the control group. Amenorrhea, disease duration, and sIGF-I were significantly associated with lumbar spine and proximal femur BMD. In a multiple regression model, we found that sIGF-I was the only significant independent predictor of proximal femur BMD, while duration of amenorrhea was the only factor associated with lumbar spine BMD. Finally, femoral neck bone mineral apparent density, but not hip geometry variables, was correlated with sIGF-I. In anorexia nervosa, spine BMD was related to hypogonadism, whereas sIGF-I predicted proximal femur BMD. The site-specific effect of sIGF-I could be related to reduced volumetric BMD rather than to modified hip geometry.
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Sumner, Dale R., Terrance C. Devlin, D. Winkelman, and Thomas M. Turner. "The geometry of the adult canine proximal femur." Journal of Orthopaedic Research 8, no. 5 (September 1990): 671–77. http://dx.doi.org/10.1002/jor.1100080508.
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Moulton, Darrell L., Ronald W. Lindsey, and Zbigniew Gugala. "Proximal Femur Size and Geometry in Cementless Total Hip Arthroplasty Patients." F1000Research 4 (June 23, 2015): 161. http://dx.doi.org/10.12688/f1000research.6554.1.
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Introduction:Accurate femoral prosthesis press-fit is essential for successful cementless total hip arthroplasty (cTHA) and dependent upon proximal femur size and geometry. Study objectives were to determine the variability of proximal femur size and geometry in primary cTHA patients and correlate them with patient demographics and body mass index (BMI).Methods:Medical records of 127 consecutive primary cTHA patients were reviewed retrospectively. The demographic (ethnicity, sex, age) and BMI data were collected. Intertrochanteric (IT) distance, inner/outer proximal femur diameters and cortical thickness for the subtrochanteric (ST) and cortical diaphyseal (DP) regions were measured from anteroposterior radiographs. Descriptive statistics were used to correlate patient demographics and BMI with radiographic measurements.Results:The study included 96 cTHA patients (mean age 60 years, range 22-91 years; 34 females; 72 Caucasian, 18 Black, and six Hispanic) with four underweight; 13 normal; 34 overweight, and 45 obese BMI. No correlation existed for patient age or race with radiographic measurements. Males had significantly larger proximal femur dimensions and cortical thickness than females. No BMI correlations existed for IT distance; BMI was directly proportional to outer diameter and cortical thickness in ST and DP regions, and inversely proportional to inner diameter in these regions.Discussion:Greater proximal femur size appears to correlate with gender, but not with age or race. Larger subtrochanteric and diaphyseal outer diameters are significantly associated with higher BMI. A trend exists for larger subtrochanteric and diaphyseal inner diameters to be associated with lower BMI. These findings may have implications for optimal cTHA femoral component design.
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Siwach, Ramchander. "Anthropometric Study of Proximal Femur Geometry and Its Clinical Application." Annals of the National Academy of Medical Sciences (India) 54, no. 04 (October 2018): 203–15. http://dx.doi.org/10.1055/s-0040-1712831.
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ABSTRACTThe implants for fixation of proximal femur fractures and joint replacements have been designed taking into consideration of the anthropometry of the western population which vary from other ethnic groups. The present study aimed to study the morphology of the upper end of femur in relation to its various diameters and angles and compare the external and internal geometry of proximal femur as obtained from radiographs, with actual measurements on cadaveric specimens in Indian population. Seventy five pairs (150 bones) of cadaveric femora were studied morphologically and radiologically using standardized techniques to obtain various anthropometrics measurements. These values were compared with those reported in the literature for Hong Kong Chinese, Caucasian, Chinese and Western populations. Data were found to be quite different from them. It is proposed that implants designed for Western populations should be used judiciously and future implants be designed to match the morphology of the Indian bones.
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Pisharody, S., R. Phillips, and C. M. Langton. "Sensitivity of proximal femoral stiffness and areal bone mineral density to changes in bone geometry and density." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 222, no. 3 (March 1, 2008): 367–75. http://dx.doi.org/10.1243/09544119jeim307.
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Areal bone mineral density (aBMD) is the most common surrogate measurement for assessing the bone strength of the proximal femur associated with osteoporosis. Additional factors, however, contribute to the overall strength of the proximal femur, primarily the anatomical geometry. Finite element analysis (FEA) is an effective and widely used computer-based simulation technique for modelling mechanical loading of various engineering structures, providing predictions of displacement and induced stress distribution due to the applied load. FEA is therefore inherently dependent upon both density and anatomical geometry. FEA may be performed on both three-dimensional and two-dimensional models of the proximal femur derived from radiographic images, from which the mechanical stiffness may be predicted. It is examined whether the outcome measures of two-dimensional FEA, two-dimensional, finite element analysis of X-ray images (FEXI), and three-dimensional FEA computed stiffness values of the proximal femur are more sensitive than aBMD to changes in trabecular bone density and femur geometry. It is assumed that if an outcome measure follows known trends with changes in density and geometric parameters, then an increased sensitivity will be indicative of an improved prediction of bone strength. All three outcome measures increased non-linearly with trabecular bone density, increased linearly with cortical shell thickness and neck width, decreased linearly with neck length, and were relatively insensitive to neck-shaft angle. For femoral head radius, aBMD was relatively insensitive, with two-dimensional FEXI and three-dimensional FEA demonstrating a non-linear increase and decrease in sensitivity respectively. For neck anteversion, aBMD decreased non-linearly, whereas both two-dimensional FEXI and three-dimensional FEA demonstrated a parabolic-type relationship, with the maximum stiffness being achieved at an angle of approximately 15°. Multi-parameter analysis showed that all three outcome measures demonstrated their highest sensitivity to a change in cortical thickness. When changes in all input parameters were considered simultaneously, three and two-dimensional FEA had statistically equal sensitivities (0.41 ± 0.20 and 0.42 ± 0.16 respectively, p= ns) that were significantly higher than the sensitivity of aBMD (0.24 ± 0.07; p=0.014 and 0.002 for three-dimensional and two-dimensional FEA respectively). This simulation study suggests that since mechanical integrity and FEA are inherently dependent on anatomical geometry, FEXI stiffness, being derived from conventional two-dimensional radiographic images, may provide an improvement in the prediction of bone strength of the proximal femur than currently provided by aBMD.
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Laskey, M. A., R. I. Price, B. C. C. Khoo, and A. Prentice. "Proximal femur structural geometry changes during and following lactation." Bone 48, no. 4 (April 2011): 755–59. http://dx.doi.org/10.1016/j.bone.2010.11.016.
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Taylor, M., and E. W. Abel. "Finite Element Analysis of Poor Distal Contact of the Femoral Component of a Cementless Hip Endoprosthesis." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 207, no. 4 (December 1993): 255–61. http://dx.doi.org/10.1243/pime_proc_1993_207_304_02.
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The difficulty of achieving good distal contact between a cementless hip endoprosthesis and the femur is well established. This finite element study investigates the effect on the stress distribution within the femur due to varying lengths of distal gap. Three-dimensional anatomical models of two different sized femurs were generated, based upon computer tomograph scans of two cadaveric specimens. A further six models were derived from each original model, with distal gaps varying from 10 to 60 mm in length. The resulting stress distributions within these were compared to the uniform contact models. The extent to which femoral geometry was an influencing factor on the stress distribution within the bone was also studied. Lack of distal contact with the prosthesis was found not to affect the proximal stress distribution within the femur, for distal gap lengths of up to 60 mm. In the region of no distal contact, the stress within the femur was at normal physiological levels associated with the applied loading and boundary conditions. The femoral geometry was found to have little influence on the stress distribution within the cortical bone. Although localized variations were noted, both femurs exhibited the same general stress distribution pattern.
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Narloch, Jerzy, and Wojciech M. Glinkowski. "Osteoarthritis Changes Hip Geometry and Biomechanics Regardless of Bone Mineral Density—A Quantitative Computed Tomography Study." Journal of Clinical Medicine 8, no. 5 (May 12, 2019): 669. http://dx.doi.org/10.3390/jcm8050669.
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We aimed to compare proximal femur geometry and biomechanics in postmenopausal women with osteoarthritis (OA) and/or osteoporosis (OP), using quantitative computed tomography (QCT). A retrospective analysis of QCT scans of the proximal femur of 175 postmenopausal women was performed. Morphometric and densitometric data of the proximal femur were used to evaluate its biomechanics. We found, 21 had a normal bone mineral density (BMD), 72 had osteopenia, and 81 were diagnosed with OP. Radiographic findings of hip OA were seen in 43.8%, 52.8%, and 39.5% of the normal BMD, osteopenic, and OP groups, respectively (p < 0.05). OA was significantly correlated with total hip volume (r = 0.21), intertrochanteric cortical volume (r = 0.25), and trochanteric trabecular volume (r = 0.20). In each densitometric group, significant differences in hip geometry and BMD were found between the OA and non-OA subgroups. Hip OA and OP often coexist. In postmenopausal women, these diseases coexist in 40% of cases. Both OA and OP affect hip geometry and biomechanics. OA does so regardless of densitometric status. Changes are mostly reflected in the cortical bone. OA leads to significant changes in buckling ratio (BR) in both OP and non-OP women.
Dissertations / Theses on the topic "Proximal femur geometry"
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Yadav, Priti. "Multiscale Modelling of Proximal Femur Growth : Importance of Geometry and Influence of Load." Doctoral thesis, KTH, Strukturmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209149.
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Longitudinal growth of long bone occurs at growth plates by a process called endochondral ossification. Endochondral ossification is affected by both biological and mechanical factors. This thesis focuses on the mechanical modulation of femoral bone growth occurring at the proximal growth plate, using mechanobiological theories reported in the literature. Finite element analysis was used to simulate bone growth. The first study analyzed the effect of subject-specific growth plate geometry over simplified growth plate geometry in numerical prediction of bone growth tendency. Subject-specific femur finite element model was constructed from magnetic resonance images of one able- bodied child. Gait kinematics and kinetics were acquired from motion analysis and analyzed further in musculoskeletal modelling to determine muscle and joint contact forces. These were used to determine loading on the femur in finite element analysis. The growth rate was computed based on a mechanobiological theory proposed by Carter and Wong, and a growth model in the principal stress direction was introduced. Our findings support the use of subject- specific geometry and of the principal stress growth direction in prediction of bone growth. The second study aimed to illustrate how different muscle groups’ activation during gait affects proximal femoral growth tendency in able-bodied children. Subject-specific femur models were used. Gait kinematics and kinetics were acquired for 3 able-bodied children, and muscle and joint contact forces were determined, similar to the first study. The contribution of different muscle groups to hip contact force was also determined. Finite element analysis was performed to compute the specific growth rate and growth direction due to individual muscle groups. The simulated growth model indicated that gait loading tends to reduce neck shaft angle and femoral anteversion during growth. The muscle groups that contributes most and least to growth rate were hip abductors and hip adductors, respectively. All muscle groups’ activation tended to reduce the neck shaft and femoral anteversion angles, except hip extensors and adductors which showed a tendency to increase the femoral anteversion. The third study’s aim was to understand the influence of different physical activities on proximal femoral growth tendency. Hip contact force orientation was varied to represent reported forces from a number of physical activities. The findings of this study showed that all studied physical activities tend to reduce the neck shaft angle and anteversion, which corresponds to the femur’s natural course during normal growth. The aim of the fourth study was to study the hypothesis that loading in the absence of physical activity, i.e. static loading, can have an adverse effect on bone growth. A subject-specific model was used and growth plate was modeled as a poroelastic material in finite element analysis. Prendergast’s indicators for bone growth was used to analyse the bone growth behavior. The results showed that tendency of bone growth rate decreases over a long duration of static loading. The study also showed that static sitting is less detrimental than static standing for predicted cartilage-to-bone differentiation likelihood, due to the lower magnitude of hip contact force. The prediction of growth using finite element analysis on experimental gait data and person- specific femur geometry, based on mechanobiological theories of bone growth, offers a biomechanical foundation for better understanding and prediction of bone growth-related deformity problems in growing children. It can ultimately help in treatment planning or physical activity guidelines in children at risk at developing a femur or hip deformity.QC 20170616
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Osborne, Daniel L. "An analysis of developmental plasticity in structural geometry at the proximal femur in adolescent females living in the United States." [Bloomington] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3264308.
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Thesis (Ph.D.)--Indiana University, Dept. of Anthropology, 2007.Source: Dissertation Abstracts International, Volume: 68-05, Section: A, page: 2031. Advisers: Della Collins Cook; David Burr. Title from dissertation home page (viewed Jan. 9, 2008).
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Goebel, Michael. "Geometrie von distalem Femur und proximaler Tibia und simulierte Implantation von Kniegelenksendoprothesensystemen." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962075760.
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Senra, Ana Rita Tavares Sousa. "Proximal Femur Geometry: A major predictor of proximal femur fracture subtypes." Master's thesis, 2021. https://hdl.handle.net/10216/139730.
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Background: Proximal femur geometry (PFG) represents an important risk factor for the occurrence of hip fractures. There are currently few studies regarding the correlation between PFG and the occurrence of a specific fracture subtype, and those that exist have small cohorts and present with different methodologies and contradictory results. Therefore, there is no consensus in the literature regarding this topic. The present study aimed to establish the contribution of the PFG in the occurrence of different subtypes of proximal femur fractures (PFF): intertrochanteric, neck and subtrochanteric.
Methods: Analysis of 1022 plain anteroposterior pelvic radiographs of patients consecutively admitted to the emergency room of a Level 1 Trauma Center between 2013 and 2019 after low energy trauma who presented with PFF and underwent surgical treatment. Patients were analyzed considering age, gender and subtype of PFF (intertrochanteric, neck or subtrochanteric). Radiological parameters including cervicodiaphyseal angle (CDA), horizontal offset (HO), femoral neck width (FNW), femoral neck length (FNL), great trochanter-pubic symphysis distance (GTPSD), acetabular teardrop distance (ATD) and width of the intertrochanteric region (WIR) were measured and compared between the different subtypes of fractures (7154 measurements). Statistical analysis was conducted recurring to absolute measurements and measurements ratios. The correlation was assessed using t-test.
Results: There were statistically significant differences in proximal femur geometry between the different subtypes of fractures. Patients presenting with femoral neck fractures had greater CDA (132.5 ± 6.9 vs 130.0 ± 7.3, p<0.001) and lower HO (45.8 ± 7.4 vs 49.0 ± 8.0, p<0.001), HO/ATD (0.34 ± 0.068 vs 0.37 ± 0.072, p<0.001) and HO/GTPSD (0.26 ± 0.049 vs 0.28 ± 0.039, p<0.001) than patients with intertrochanteric/subtrochanteric fractures.
Conclusion: PFG represents an important contributor to the occurrence of different fracture subtypes. Femoral neck fractures are associated with greater CDA and lower HO, HO/ATD and HO/GTPSD when compared to intertrochanteric or subtrochanteric fractures.
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Cardadeiro, Maria da Graça Sousa Gato. "Skeleton geometry, physical activity and proximal femur bone mass distribution in 8-12 year old children." Doctoral thesis, 2013. http://hdl.handle.net/10400.5/6496.
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Doutoramento em Motricidade Humana, especialidade em Actividade Física e SaúdeIn the context of bone health promotion, the aim of this Ph.D dissertation was to analyze potential explanatory factors of the effects of physical activity and of bone geometry on bone mass distribution at the proximal femur in 8-12 year old children. Four studies were undertaken to compare the bone mineral density (BMD) between: (a) the sub-regions of the proximal femur – the neck and its superolateral and inferomedial aspects, the trochanter and the intertrochanter; (b) sexes, concerning the associations/effects of non-targeted physical activity and bone geometry. Sex and regional specific effects of non-targeted physical activity on bone mass distribution at the proximal femur in children were observed. The geometry of the pelvis and the proximal femur, namely the pelvis width and the abductor lever arm, emerged as predictors of bone mass distribution at the proximal femur, therefore as explanatory factors of both the regional and the sex specific patterns. These geometric features might mediate the physical activity effects on bone mineralization at the proximal femur, as long as, when they are considered, the power of physical activity to explain the distribution of bone mass at this skeletal site seems limited.
Resumo : No contexto da promoção da saúde óssea, o objetivo desta dissertação de doutoramento foi analisar potenciais fatores explicativos dos efeitos da atividade física habitual e da geometria óssea na distribuição da massa óssea do fémur proximal, em crianças de 8-12 anos de idade. Para o efeito foram realizados quatro estudos comparando a densidade mineral óssea (DMO) entre: (a) as diversas sub-regiões do fémur proximal - o colo do fémur e os seus aspetos supero-lateral e infero-medial, o grande trocanter e a sub-região intertrocantérica; (b) os sexos, relativamente às associações/efeitos da atividade física habitual e da geometria óssea. Foram observadas associações/efeitos da atividade física habitual na massa óssea do fémur proximal diferenciados quanto ao sexo e sub-região. A geometria da pélvis e do femur proximal, nomeadamente a largura da pélvis e o braço de momento de força dos abdutores, surgiram como preditores da distribuição de massa óssea no fémur proximal e consequentemente como fatores explicativos de diferenciação da distribuição de massa óssea de acordo com o sexo e sub-região. Estas caraterísticas geométricas poderão mediar os efeitos da atividade física na mineralização do femur proximal uma vez que quando consideradas parecem limitar a capacidade explicativa da atividade física na distribuição de massa óssea no fémur proximal.
FCT - Fundação para a Ciência e a Tecnologia
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Manske, Sarah Lynn. "Magnetic resonance imaging as an instrument to assess the association between femoral neck bone geometry and strength of the proximal femur." Thesis, 2005. http://hdl.handle.net/2429/17246.
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Introduction: Hip fractures are an increasing health and economic burden. Dual energy x-ray
absorptiometry (DXA) is the instrument currently used to diagnose osteoporosis, however, there
are limitations associated with using DXA to predict fracture risk and to measure response to
therapeutic interventions. Magnetic resonance imaging (MRI) is an emerging instrument to assess
bone, however the ability of MRI measurements of femoral neck geometry to predict bone
strength has not been previously assessed.
Objectives: To evaluate the association of femoral neck cross-sectional geometry measured with
MRI with failure load in cadaveric femora, and to compare this association with DXA and Hip
Structural Analysis (HSA). The secondary objective was to compare reliability of femoral neck
geometry measured with 3 Tesla (T) MRI and 1.5 T MRI systems.
Methods: Thirty-six human cadaveric proximal femora underwent DXA and MRI imaging.
DXA images were also analyzed with HSA. Areal BMD (aBMD) was evaluated with DXA and
HSA. Cross-sectional geometry (area, second area moment of inertia - Ix, and section modulus)
were evaluated with MRI (femoral neck region) and HSA (narrow neck and intertrochanteric
regions). Inter-analysis and inter-acquisition reliability were compared between measurements
with 1.5 T and 3 T MRI systems. The femora were loaded to failure in a fall configuration.
Results: Femoral neck cortical cross-sectional area and Ix, measured with MRI, were strongly
associated with failure load (R² = 0.47 for both measures, p < 0.001). The predictive ability of Ix
was lower than trochanteric aBMD (R² = 0.70), p = 0.10. Ix significantly contributed to the
variance explained in failure load after accounting for femoral neck aBMD (R2-change = 0.14, p
= 0.01), but not after accounting for trochanteric aBMD (R²-change = 0.03, p = 0.23). Crosssectional
geometry, e.g. Ix, measured with MRI explained similar variance in failure load (R² =
0.47) as cross-sectional geometry estimated with HSA (R² = 0.31). Inter-acquisition and interanalysis
reliability were similar for 3 T and 1.5 T MRI systems.
Summary and Conclusion: Femoral neck cross-sectional geometry assessed with MRI and
HSA, and aBMD by DXA were similarly associated with failure load ex vivo. MRI holds
promise for the in vivo assessment of cortical bone geometry at the proximal femur, as neither
DXA nor HSA are capable of measuring these parameters without major assumptions. However,
a targeted program of research that aims to improve and standardize MRI image acquisition and
analysis is warranted.Medicine, Faculty of
Medicine, Department of
Experimental Medicine, Division of
Graduate
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Tai, Ching-Lung, and 戴金龍. "The Effect of Geometry and Fixation Modes of Total Hip Prosthesis on the Stress Shielding of Proximal Femur in Total Hip Arthroplasty." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/zbz7ts.
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博士中原大學
醫學工程研究所
93
ABSTRACT Surgical reconstruction of the hip with total joint arthroplasty has proven to be a successful surgical procedure due to the improvements of prosthetic design, biomaterials and surgical technique. However, the success of the surgery it is limited by the mechanical failure of stem loosening. Stress shielding and osteolysis are considered to be the main factors causing loosening. Until now, the influence of stem geometry and fixation modes on stress shielding and bone loss remains controversial. Numerous investigations have been done to examine the stress shielding and adaptive bone remodeling following total hip arthroplasty. All the results have indicated that, in actual applications, the addition to the femur with any stem-type implant would cause certain degree of stress shielding. However, the effects of stem geometry and the bone cement on the degree of stress shielding still remains controversial. To date, although a number of researches have been done on the related topic, however, it lacks an integral approach, an integration of in vitro experiments, simulated stress analyses and clinical evaluations, to examine the above-mentioned problems. This study systematically conducted a tripled approach involving experimental measurement, finite element analysis and clinical follow-up to examine the stress shielding and bone loss following total hip arthroplasty. There are three objectives in this study; the first objective is to investigate the influence of stem geometry (straight or curved) on the degree of stress shielding. The second objective is to investigate the effect of cement in different fixation configurations on the degree of stress shielding, and the third objective is to develop an ideal stemless cevico-trochanteric (C-T) stem to avoid the stress shielding and bone loss that the conventional stem-type prosthesis encountered. In the exploration on the role of stem geometry, the straight (C-fit) and curved (PCA) stems with cementless fixation were examined. Strain measurement was performed using synthetic femur before and after stems insertion, and the surface strains were compared between two groups. Besides, a randomized retrospective analysis was also conducted using Dual-energy X-ray absorptiometry. Periprosthetic bone mineral density for patients who underwent straight and curved stems replacement was measured and compared. In the exploration on the role of cement fixation, C-fit stem implanted with three different configurations of cement fixation (cementless, proximally-cemented and fully-cemented) were compared using finite element analysis. An additional prospective follow-up was also conducted for patients who underwent total hip arthroplasty with C-fit stem by cementless, proximally- and fully-cemented fixations. Finally, in the exploration on the newly designed C-T stemless prosthesis, static tests with strain measurement combined with cyclic tests up to failure were performed to evaluate the mechanical characteristics of this new stemless prosthesis. The results of in vitro test and finite element analysis are well corresponding to those of clinical follow-up. The results indicated that the curved PCA stem induces more stress shielding and causes a more significant bone loss as compared to those of straight C-fit stem. Furthermore, stem implanted with cementless fixation experienced the most significant stress shielding and bone loss as compared to those of either proximally- or fully-cemented. The application of bone cement tends to decrease stress shielding and normalizes the proximal femoral stress. Additionally, the C-T stemless prosthesis exhibited a more physiological stress distribution as compared to those of the traditional stem-type prosthesis. We concluded that, in the six combinations of stem geometry and fixation modes, curved stem combined with cemented fixation would induce the most stress shielding in doing hip replacement. The C-T implanted femur has more physiological strain distribution and satisfactory interfacial bonding with cement fixation.
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Meyers, Julia Luba. "The relationship between proximal long bone shape and activity among four hunter-gatherer populations." Thesis, 2017. https://dspace.library.uvic.ca//handle/1828/8460.
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There is an understanding among biological anthropologists that long bone epiphyseal shape is highly regulated by genetic and biomechanical factors. Conversely, long bone diaphyseal geometry and robusticity have been shown to respond to activity in life. The current study examined the assumption of epiphyseal consistency by exploring the relationship between a well established bony response to activity (Cross-Sectional Geometry) and shape change among the proximal humerus and femur. Long bone samples were taken from four hunter-gatherer populations: the Andaman Islanders, the Indian Knoll, Point Hope Alaskans, and the Sadlermiut. Shape was measured through landmark configurations placed on the proximal end of a total of 91 humeri and 84 femora. Cross-sectional Geometry measures (J) were taken from each specimen, as well. Principal Component Analyses were conducted on the landmark shape data to determine where the shape variation was occurring among the sample. These Principal Components were then compared via Bivariate Regression to the J values taken from the diaphysis.
Significant relationships occurred between the development of the lesser tubercle and an increase in J among the humerus sample. Significant relationships were also found among the femur sample; as when J increased the proximal epiphyses were more likely to be more gracile, and the space between the femoral head and the greater trochanter increased. The humerus results indicated a more robust proximal epiphysis in groups with activities that rely heavily on the upper body, such as rowing, swimming, and harpooning. The femur results were more complex, as the relationship between activity and proximal shape is likely heavily influenced by a genetically predetermined body shape. These results indicated that there is a relationship between activity and proximal epiphyseal shape, but that it, like all relationships, is complex, and comprised of multiple factors. Ultimately, proximal long bone shape is the result of multiple influences including, activity, genetics, population adaptation, health, and many more. Future research should focus on determining if the relationship between activity and shape exists among other populations, and when and where it begins during growth and development.Graduate
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Goebel, Michael [Verfasser]. "Geometrie von distalem Femur und proximaler Tibia und simulierte Implantation von Kniegelenksendoprothesensystemen / Michael Goebel." 2000. http://d-nb.info/962075760/34.
Full textBook chapters on the topic "Proximal femur geometry"
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Matsuda, Yasumasa, Kazuhiko Sawai, Tomokazu Hattori, and Shigeo Niwa. "Analysis of the Endosteal Geometry of the Proximal Femur in Japanese Patients with Osteoarthritic Hips: Use in Femoral Stem Design." In Hip Biomechanics, 303–12. Tokyo: Springer Japan, 1993. http://dx.doi.org/10.1007/978-4-431-68237-0_28.
Full textConference papers on the topic "Proximal femur geometry"
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Wang, Eric L., Yanyao Jiang, Lixia Fan, and Brian Greer. "Sensitivity of Modeling Parameters in Proximal Femur Analyses." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2589.
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Abstract Hip fracture risk can be quantified using a factor of risk (Hayes et al., 1996): (1) Φ = Applied load / Fracture load The structural capacity, the denominator, can be affected by many parameters including femoral geometry, material properties, load locations, loading direction, loading rate, and frictional resistance.
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Yutzy, Joseph D., and Erik R. Bardy. "Average Periosteal Stress of the Proximal Femur Before and After Cementless Total Hip Arthroplasty." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-203800.
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Cementless Total Hip Arthroplasty (THA) is a standard surgical technique for the treatment of several types of joint diseases and damages including, but not limited to, osteoarthritis and femoral neck fracture [1]. An estimated one half to one million total hip replacements are performed each year [2]. Two drawbacks to THA are (1): micromotions as a result of improper implant fit in the bone cavity [1], and (2): stress shielding due to unnatural stress concentrations near the implant [3]. The latter causes bone resorption in other areas found in the bone-implant interface [1]. Therefore, the geometry and size of the implant is a major factor in determining cortical stress distributions and stress shielding [4].
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Liu, X. Sherry, Adi Cohen, Perry T. Yin, Joan M. Lappe, Robert R. Recker, Elizabeth Shane, and X. Edward Guo. "Relationships Between Stiffness of Human Distal Tibia, Distal Radius, Proximal Femur, and Vertebral Body Assessed by HR-pQCT and cQCT Based Finite Element Analyses." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-205457.
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High-resolution peripheral quantitative computed tomography (HR-pQCT) is a promising clinical tool that permits separate measurements of trabecular and cortical bone compartments at the distal radius and tibia. It has an isotropic voxel size of 82 μm, which is high enough to assess the fine microstructural details of trabecular architecture. HR-pQCT images can also be used for building microstructural finite element (μFE) models to estimate the mechanical competence of whole bone segments. Melton et al. showed that derived bone strength parameters (axial rigidity and fall load to failure load ratio) are additional to BMD and bone geometry and microstructure as determinants of forearm fracture risk prediction [1]. Boutroy et al. found that the proportion of the load carried by trabecular bone versus cortical bone is associated with wrist fracture independently of BMD and microarchitecture [2]. These clinical studies demonstrate that HR-pQCT based μFE analyses can provide measurements of mechanical properties that independently associate with fracture risk. However, microstructure of one skeletal site may be different from that of another site. It is unclear whether and to what extent these peripheral measurements reflect the bone strength of the proximal femur and vertebral bodies, the sites of frequent osteoporotic fractures. Currently, central quantitative computed tomography (cQCT) is the most commonly used clinical imaging modality to quantify the structural and mechanical properties of the proximal femur and lumbar spine. We therefore evaluated relationships between the stiffness of the distal radius and tibia estimated by HR-pQCT-based FEA with that of the proximal femur and lumbar spine which was estimated from cQCT-based FEA in the same human subjects.
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Fox, Julia C., and Tony M. Keaveny. "Role of Trabecular Bone Distribution in Femoral Neck Biomechanics." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2591.
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Abstract Body weight, habitual postures and activities are the primary determinants of the nature and magnitude of loads acting on the proximal femur, the distribution of which influences the development of the bone structure and geometry (Wolff, 1892). This phenomena, called functional adaptation, has long been an area of interest in the field of bone mechanics, particularly with reference to compensatory geometric remodeling of long bones with decreasing bone mass (Martin et al. 1977; Ruff et al. 1988; Kannus et al., 1996). However, the extent to which compensatory remodeling occurs in the femoral neck remains unclear (Horikoshi, 1999; Beck, 1993). A potential adaptation of the femoral neck may be characterized by the asymmetric distribution of trabecular and cortical bone in the femoral neck cross-section, i.e. there is a disparity in superior and inferior cortical thickness (Bell, 1999; Boyce, 1993), referred to here as an eccentricity.
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Ondrake, J. E., K. C. Lifer, S. P. Haman, J. E. Marquart, and Hui Shen. "Single Screw vs. Double Screw Device for Use in Treating Femoral Bone Fractures." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38676.
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Proximal femur fractures commonly occur between the head of the femur and the femoral shaft. As the third most common injury encountered in orthopedic clinics, these fractures are typically treated with medical implants creating internal stabilization of the bone. Over 100 different implants are available for this application. Although the optimal choice for the implants is still controversial, traditional devices which include a single cylindrical screw, such as SHS (Sliding Hip Screw) and IMHS – CP (Intramedullary Hip Screw, Clinically Proven), are widely used to repair the bone fracture. However, the application of the single screw device still suffers technical problems. The head of the femur has the potential to rotate about the screw and the fracture surfaces have potential to slide over each other. In addition, force relaxation can occur, leading to inadequate contact between the fracture surfaces. To attack these problems and prevent possible complications, a new device has been developed. The new device consists of one long screw interlocked with one short screw, creating a cross-sectional figure-eight pattern and offering an integrated, interlocking screw option. The objective of the current study is to compare biomechanical characteristics within the bone caused by the new double screw device verses the traditional single screw device. Experiments were preformed to compare the torsional stiffness of the two devices. 2D and 3D finite element analysis methods were carried out to obtain macroscopic and microscopic responses of each device’s interaction with the fractured bone. The modeled results show a significant difference between the two geometries. The single screw geometry has higher maximum total deformation, equivalent strain, equivalent von Mises stress, and maximum principle stress. The improved rotational stability of the new double screw device may reduce the complication rate of instability of the fracture fragments.
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Pisano, A. A. "A limit analysis approach for the prediction of the human proximal femur ultimate load." In AIMETA 2022. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902431-47.
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Abstract. A limit analysis numerical procedure for the determination of a lower bound on the ultimate load of the human proximal femur is presented. The procedure, already applied by the authors in different contexts, is based on a simplified 3D geometrical model of the human femur and on the assumption of a few geometric and material data available in the relevant literature. The perfectly plastic behaviour of the human bone, due to phenomena starting at molecular scale, and the orthotropic behaviour of the main human femur tissues, trabecular and cortical, allows to assume a yield surface of Tsai-Wu-type for its constitutive description. The effectiveness of the promoted numerical approach is validated by comparison of the obtained results with experimental findings on in-vitro tests of human femurs.
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Khandaker, Morshed, Sadegh Nikfarjam, Karim Kari, Onur Can Kalay, Fatih Karpat, Helga Progri, Ariful Bhuiyan, Erik Clary, and Amgad Haleem. "Laser Microgrooving and Nanofiber Membrane Application for Total Knee Replacement Implants Using a Caprine Model." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73597.
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Abstract Aseptic loosening is a well-recognized phenomenon in cementless total knee replacement (TKR) and often carries severe consequences for the patient. We recently developed and tested in vitro a novel strategy for enhancing osseointegration and acute mechanical stability of orthopedic implants that employ laser-induced microgroove (LIM) and nanofiber membrane (NFM) applications at the bone-implant interface. We report herein investigation of the approach with results from a pilot study employing three skeletally mature female Spanish cross goats (∼4y, 35–45kg) receiving cementless TKR with a commercially available implant system (Biomedrix® Canine Total Knee). Pre-operative radiographs were taken to ensure limb normality and to select the appropriately sized implants for each goat. With the animal under general anesthesia and the limb properly prepped for aseptic surgery, the stifle was approached, and osteotomies of the proximal tibia and distal femur performed in preparation for implantation of the tibial (TT) and femoral (FT) trays. For one goat, the arthroplasty implant surfaces were unaltered from the manufacturer’s mirror-polished (MP) condition. For the other two goats, the TT bone-contact surface was laser-micro grooved (150 μm depth, 200 μm width, 200 μm spacing) prior to sterilization and then implanted with (LIM/NFM) or without (LIM) an intermediate (surface-applied) polycaprolactone (PCL) nanofiber mesh (50 × 50mm, electrospun, aligned, unidirectional, 10 μm thickness). Following surgery, animals received appropriate analgesic therapy and rehabilitative care to maximize animal comfort, function, and quality of life while limiting the risk of major complications. Post-operative monitoring included assessment of mentation, vital signs, pain level, digestive function (weight, appetite, rumen contractions, feed intake, fecal output), and limb status (usage, range of motion, muscular volume). By the study’s end (12 wks), all animals had recovered a pre-surgery range of motion in the operated knee and exhibited typical bony changes on radiographic follow-up. At necropsy following humane euthanasia, no gross instability of TKR components was observed. Histomorphometric analysis of explanted bone-TT constructs showed the increased new bone surface area in the LIM-NFM sample (0.49 mm2) compared with the MP sample (0.03 mm2), suggesting that microgrooves and/or PCL nanofiber coating may improve the clinical performance of the implant. A finite element analysis (FEA) model was developed to explore the impact of surface micro grooving to the mechanical stimuli at the bone-implant interface to supplement the in vivo studies. The three-dimensional geometry of the tibia was scanned using computed tomography and imported into a proprietary (MIMICS®) software to construct the solid models for finite element micro-strain analyses.
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Yang, Chien-Chun, Mahesh B. Nagarajan, Markus B. Huber, Julio Carballido-Gamio, Jan S. Bauer, Thomas Baum, Felix Eckstein, et al. "Predicting the biomechanical strength of proximal femur specimens through high dimensional geometric features and support vector regression." In SPIE Medical Imaging, edited by John B. Weaver and Robert C. Molthen. SPIE, 2013. http://dx.doi.org/10.1117/12.2006265.
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