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The pelvic ring is a complex anatomical structure building up the connection between the trunk and the legs. Whilst there is a broad discussion in the literature about the dynamic interaction between spine, pelvis and the hip joints, there is still little information about the relation and interaction of the constant pelvic parameters. Based on a three-dimensional (3D) statistical model consisting of 150 uninjured and bony healthy pelves (100 Europeans, 50 Japanese; 81 males, 69 females; average age 74.3 years ± 17.5 years) an evaluation of pelvic incidence (PI) and acetabular orientation in anteversion and inclination was performed and potential correlations of these intraindividual constant parameters were investigated. Pelvic incidence is defined as the angle between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the middle axis of the femoral heads. Acetabular anteversion is defined as the angle between the perpendicular to the best-fit plane on the acetabular rim and the coronal plane measured in strict lateral view. Acetabular inclination is defined as the angle between the perpendicular to the best-fit plane on the acetabular rim and the sagittal plane in strict frontal view. Data were further analysed with regard to different subgroup's age, sex and ethnicity. A positive correlation between PI and acetabular anteversion could be demonstrated. Further, PI and also the acetabular parameters anteversion and inclination were found to be significantly higher in the European individuals than in the Asian. The results of the present study demonstrate a relation between the anatomical configuration of the constant pelvic parameters building up the connection points to the next proximal respectively caudal skeleton section. The findings might lead to more comprehensive treatment strategies in case of trauma or degenerative pathologies of the pelvis in the future.
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Acetábulo , Huesos Pélvicos , Acetábulo/diagnóstico por imagen , Anciano , Femenino , Articulación de la Cadera , Humanos , Masculino , Modelos Estadísticos , Huesos Pélvicos/diagnóstico por imagen , PelvisRESUMEN
The human pelvis is a complex anatomical structure that consists of the innominate bones, sacrum and coccyx to form the pelvic ring. Even though considered to be a symmetric entity, asymmetry of the pelvic ring (APR) might occur to alter its anatomy, function, or biomechanics or to impact assessment and treatment of clinical cases. APR and its assessment is complicated by the intricate anatomy of the pelvic ring. There is only limited information and understanding about APR with no established evaluation methods existing. The objective of the present study was to adopt CT-based 3D statistical modeling and analysis to assess APR within the complex anatomy of the pelvic ring. We were interested to establish a better understanding of APR with knowledge and applications transferred to human anatomy, related research, and development subjects and to clinical settings. A series of 150 routine, clinical, pelvic CT protocols of European and Asian males and females (64 ± 15 (20-90) years old) were post-processed to compute gender- and ancestry-specific 3D statistical models of the pelvic ring. Evaluations comprised principal component analysis (PCA) that included size, shape, and asymmetry patterns and their variations to be assessed. Four different CT-based 3D statistical models of the entire pelvic ring were computed according to the gender and ancestry specific groups. PCA mainly displayed size and shape variations. Examination of additional PCA modes permitted six distinct asymmetry patterns to be identified. They were located at the sacrum, iliac crest, pelvic brim, pubic symphysis, inferior pubic ramus, and near to the acetabulum. Accordingly, the pelvic ring demonstrated not to be entirely symmetric. Assessment of its asymmetry proved to be a challenging task. Using CT-based 3D statistical modeling and PCA, we identified six distinct APRs that were located at different anatomical regions. These regions are more prone to APRs than other sites. Minor asymmetry patterns have to be distinguished from the distinct APRs. Side differences with regard to size, shape, and/or position require to be taken into account. APRs may be due different load mechanisms applied via spine or lower extremity or locally. There is a need for simpler and efficient, yet reliable methods to be routinely transferred to human anatomy, related research, and development subjects and to clinical settings.
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Huesos Pélvicos/diagnóstico por imagen , Pelvis/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Tomografía Computarizada por Rayos X , Adulto JovenRESUMEN
The pelvic ring is a highly complex construct with a central role for human stability and mobility. The observable interindividual differences in skeletal anatomy are caused by anatomical variation in the innominate bones as well as the sacrum, further to differences in the spatial arrangement of these bones to each other. The aim of this study was to generate a 3D statistical model of the entire pelvic ring in order to analyse the observed interindividual differences and anatomical variation. A series of 50 anonymized pelvic CT scans of uninjured Japanese adults [30 males, 20 females, average age of 74.9 years, standard deviation (SD) 16.9 years] were processed and analysed, resulting in a 3D statistical overall mean model and separate male and female mean models. Principal component analysis (PCA) of the overall statistical model predominantly showed size variation (20.39%) followed by shape variation (14.13%), and a variation of the spatial arrangement of the sacrum to the innominate bones in different anatomical peculiarities (11.39 and 8.85%). In addition, selected internal and external pelvic parameters were manually measured with the objective of further evaluating and quantifying the observed interindividual as well as the known sex-specific differences. A separate statistical model of the grey value distribution based on the given Hounsfield unit (HU) values was calculated for assessing bone mass distribution, thus an indication of bone quality utilizing grey values as a quantitative description of radiodensity was obtained. A consistent pattern of grey value distribution was shown, with the highest grey values observed between the sacro-iliac joint and the acetabulum along the pelvic brim. Low values were present in the sacral ala, in the area of the iliac fossa as well as in the pubic rami next to the symphysis. The present model allows a differentiated analysis of the observed interindividual variation of the pelvic ring and an evaluation of the grey value distribution therein. Besides providing a better understanding of anatomical variation, this model could be also used as a helpful tool for educational purposes, preoperative planning and implant design.
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Variación Anatómica , Imagenología Tridimensional/métodos , Huesos Pélvicos/anatomía & histología , Pelvis/anatomía & histología , Sacro/anatomía & histología , Adulto , Anciano , Biometría , Femenino , Identidad de Género , Humanos , Ilion/anatomía & histología , Masculino , Modelos Estadísticos , Análisis de Componente Principal , Articulación Sacroiliaca/anatomía & histología , Tomografía Computarizada por Rayos X/métodosRESUMEN
Distal radius fractures are common and fracture patterns and fixation can be complex. Computerized anatomy evaluation (CAE) might offer non-invasive and enhanced anatomy assessment that might help with implant selection and placement and screw length determination. Our goal was to test the accuracy of two CAE methods for anatomical volar plate positioning and screw lengths measurement of the distal radius. We included 56 high-resolution peripheral quantitative computed tomography scans of intact, human distal radii. Plates were placed manually onto 3D printed models (method 1), which was compared with automated computerized plate placement onto the 3D computer models (method 2). Subsequently, screw lengths were determined digitally for both methods. Screw lengths evaluations were compared via Bland-Altman plots. Both CAE methods resulted in identical volar plate selection and in anatomical plate positioning. For screw length the concordance correlation coefficient was ≥0.91, the location shift ≤0.22 mm, and the scale shift ≤0.16. The differences were smaller than ±1 mm in all samples. Both CAE methods allow for comparable plate positioning and subsequent screw length measurement in distal radius volar plating. Both can be used as a non-invasive teaching environment for volar plate fixation. Method 2 even offers fully computerized assessments. Future studies could compare our models to other anatomical areas, post-operative volar plate positioning, and model performance in actual distal radius fracture instead of intact radii. Clin. Anat. 32:361-368, 2019. © 2018 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.
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Fracturas del Radio/diagnóstico por imagen , Radio (Anatomía)/anatomía & histología , Placas Óseas , Tornillos Óseos , Cadáver , Fijación Interna de Fracturas/métodos , Humanos , Imagenología Tridimensional , Procedimientos Ortopédicos/educación , Radio (Anatomía)/diagnóstico por imagen , Fracturas del Radio/cirugía , Tomografía Computarizada por Rayos XRESUMEN
INTRODUCTION: The use of trans-sacral implants to treat fractures of the sacrum is limited by the variable pelvic anatomy. We were interested in how many trans-sacral implants can be placed per pelvis? If a trans-sacral implant cannot be placed in S1, where is the cortex perforated, and is the use of sacroiliac screws safe in these pelves? MATERIALS AND METHODS: 3D pelvic models were created from CT scans of 156 individuals without fractures (92 European and 64 Japanese, 79 male and 77 female, mean age 66.7 ± 13.7 years). Trans-sacral implants with a diameter of 7.3 mm were positioned virtually with and without a surrounding safe zone of 12 mm diameter. RESULTS: Fifty-one percent of pelves accommodated trans-sacral implants in S1 with a safe zone. Twenty-two percent did not offer enough space in S1 for an implant even when ignoring the safe zone. Every pelvis had sufficient space for a trans-sacral implant in S2, in 78% including a safe zone as well. In S1, implant perforation was observed in the sacral ala and iliac fossa in 69%, isolated iliac fossa perforation in 23% and perforation of the sacral ala in 8%. Bilateral sacroiliac screw placement was always possible in S1. CONCLUSIONS: The use of trans-sacral implants in S1 requires meticulous preoperative planning to avoid injury of neurovascular structures. S2 more consistently offers space for trans-sacral implants.
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Tornillos Óseos , Fijación Interna de Fracturas/métodos , Fracturas de Cadera/cirugía , Imagenología Tridimensional/métodos , Sacro/cirugía , Cirugía Asistida por Computador/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Ilion/cirugía , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos XRESUMEN
INTRODUCTION: Patients suffering from osteoporosis-associated fragility fractures of the sacrum (FFS; also termed sacral insufficiency fractures) are increasingly observed. They have typical fracture patterns with fracture lines located in the sacral ala. When treating these patients operatively, iliosacral screw loosening is not uncommon. We aimed to study the sacral bone mass in patients presenting with a FFS using 3D statistical models. MATERIALS AND METHODS: 3D models of averaged Hounsfield units (HU) were generated based on CT scans from 13 patients with a unilateral FFS (mean age 79.6 years; 11 females, 2 males). The control group without fractures consisted of 28 males and 32 females (mean age of 68.3 years). A virtual bone probe along the trans-sacral corridors S1 and S2 was taken. RESULTS: The bone mass distribution in the fractured sacra was similar to the control group, however, with overall lower HU. Large zones of negative HU were located in the sacral ala. In the fractured sacra, the HU in the sacral ala was significantly lower on the non-injured side when comparing to the fractured side (p < 0.001) as well as compared to the non-fractured group (p < 0.001). Low bone mass was observed in sacral body S1 (40 HU) and S2 (20 HU). CONCLUSIONS: The extensive area of negative HU may explain the fracture location in the sacral ala. The low HU in the sacral bodies advocates the use of trans-sacral implants or augmented iliosacral screws to enhance the strength of fracture fixation. The increased HU in the fractured ala could be explained by fracture-asssociated hemorrhage and can be used as a diagnostic tool.
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Fracturas Osteoporóticas/diagnóstico por imagen , Sacro/lesiones , Fracturas de la Columna Vertebral/diagnóstico por imagen , Anciano , Anciano de 80 o más Años , Densidad Ósea , Tornillos Óseos , Femenino , Fijación Interna de Fracturas/instrumentación , Fijación Interna de Fracturas/métodos , Humanos , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Fracturas Osteoporóticas/cirugía , Estudios Retrospectivos , Sacro/diagnóstico por imagen , Sacro/cirugía , Fracturas de la Columna Vertebral/cirugía , Tomografía Computarizada por Rayos XRESUMEN
Osteoporosis leads to bone loss and structural deterioration, which increase the risk of fractures. The aim of this study was to characterize the three-dimensional (3D) bone mass distributions of the distal tibia in normal, osteopenic, and osteoporotic conditions. High-resolution peripheral quantitative computed tomography (HR-pQCT) of the 33 % of the distal tibia and local dual-energy X-ray absorptiometry were applied to 53 intact, fresh-frozen tibiae. The HR-pQCTs were graded to assign local T-scores and merged into three equally sized average normal, osteopenic, and osteoporotic surface models. Volumetric bone mineral density (vBMD) was determined using categorized T-scores, volumetric visualization, and virtual bore probes at the dia-, meta-, and epiphyseal sites (T-DIA, T-META, and T-EPI). We observed a distinct 3D bone mass distribution that was gradually uninfluenced by T-score categories. T-DIA was characterized by the lowest bone mass located in the medullary cavity and a wide homogenous cortex containing the maximum vBMD. The T-META showed decreased cortical thickness and maximal vBMD. At the T-EPI, the relatively low vBMD of the mostly trabecular bone was similar to the maximal cortical vBMD in this sub-region. Four trabecular regions of low bone mass were identified in the recesses. The bone content gradually decreased at all sites, whereas the pattern of bone mass distribution remained essentially unchanged, with the exception of disproportionate losses at T-DIA, T-META, and T-EPI that consistently showed increased endocortical, intracortical, and trabecular bone loss. Extra information can be obtained from the specific pattern of bone mass distribution, potential disproportionate bone losses, and method used.
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Enfermedades Óseas Metabólicas/diagnóstico por imagen , Enfermedades Óseas Metabólicas/patología , Osteoporosis/diagnóstico por imagen , Osteoporosis/patología , Tibia/diagnóstico por imagen , Tibia/patología , Absorciometría de Fotón , Densidad Ósea , Simulación por Computador , Humanos , Técnicas In Vitro , Tomografía Computarizada por Rayos XRESUMEN
Preformed cranioplasty implants form a new concept of implants to repair relatively large-sized calvarial defects. They could offer an alternative treatment to manually molded cranioplasty, and to flat or patient specific implants, while still achieving a satisfactory clinical result.We report on 3D statistical modeling and analysis performed in 80 clinical CT data of adult European Whites with unaffected calvarial bones to establish an anatomical background for the development of preformed alloplastic cranioplasty implants.Most size and shape (=form) variation was observed bilateral symmetrically in the central temporal region, showing up to 26.8 mm variation and 9.4 mm standard deviation from the mean form. Large deviation was also observed in the central lower forehead, in the central occipital region at the protuberantia occipitalis externa and laterally to it. An intermediate variation was detected at the transition area from the temporal to other regions, as well as in the frontal and occipital area. The cranial roof, the temporal fossa, and the nuchal region exhibited the lowest variability with a standard deviation of about 4 mm. Principal components analysis revealed no relevant shape but a significant size difference between genders. Size contributed to 24.4% of the overall form variability. The mean surface area difference between genders was 67 cm.The size and number of implant forms required have to be referred to the relatively large anatomical variation experienced, and also to considerations related to implant location, design, and material. A rigid material is considered to significantly increase the number of implants forms, especially when repairing relatively large-sized defects.
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Craneotomía/instrumentación , Prótesis e Implantes , Implantación de Prótesis/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Imagenología Tridimensional , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Diseño de Prótesis , Interpretación de Imagen Radiográfica Asistida por Computador , Estudios Retrospectivos , Tomografía Computarizada por Rayos XRESUMEN
PURPOSE: To detect anatomical conditions that may benefit from an orbital rim advancement procedure in patients suffering from Graves orbitopathy. METHODS: In postprocessed 70 clinical CTs from adults of white European ethnicity with unaffected orbits, the authors assessed the intra- and interindividual variability of the orbital rim angulation and orbital rim position relative to their medial rim parts. This included morphometrical analysis and computer model visualization using Amira software (version 5.3.1, Visage Imaging GmbH, Berlin, Germany). RESULTS: Significant variation was observed in rim angulation, varying up to 16.6° in different individuals. A large variability of the sagittal rim position became evident, with the highest at the lateral orbital rim being 1.1 cm. CONCLUSIONS: These anatomical data may be used to benchmark the given Graves orbitopathy patients. CT assessment to detect and quantify orbital rim pro-/retrusion may help to decide whether orbital rim advancement may be considered for orbital decompression/enlargement.
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Descompresión Quirúrgica , Oftalmopatía de Graves/cirugía , Enfermedades Orbitales/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Oftalmopatía de Graves/diagnóstico por imagen , Humanos , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional , Masculino , Persona de Mediana Edad , Enfermedades Orbitales/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Adulto JovenRESUMEN
A pragmatic method for assessing the accuracy and precision of a given processing pipeline required for converting computed tomography (CT) image data of bones into representative three dimensional (3D) models of bone shapes is proposed. The method is based on coprocessing a control object with known geometry which enables the assessment of the quality of resulting 3D models. At three stages of the conversion process, distance measurements were obtained and statistically evaluated. For this study, 31 CT datasets were processed. The final 3D model of the control object contained an average deviation from reference values of -1.07 ± 0.52 mm standard deviation (SD) for edge distances and -0.647 ± 0.43 mm SD for parallel side distances of the control object. Coprocessing a reference object enables the assessment of the accuracy and precision of a given processing pipeline for creating CT-based 3D bone models and is suitable for detecting most systematic or human errors when processing a CT-scan. Typical errors have about the same size as the scan resolution.
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Huesos/diagnóstico por imagen , Simulación por Computador/normas , Imagenología Tridimensional/métodos , Modelos Biológicos , Tomografía Computarizada por Rayos X/métodos , Algoritmos , Humanos , Imagenología Tridimensional/normas , Control de Calidad , Reproducibilidad de los Resultados , Tomografía Computarizada por Rayos X/normasRESUMEN
Transsacral corridors at levels S1 and S2 represent complex osseous spaces allowing percutaneous fixation of non- or minimally-displaced fragility fractures of the sacrum. To safely place transsacral implants, they must be completely intraosseous. However, standard radiographs and CT do not properly demonstrate the corridor's intricate configuration. Our goal was to facilitate the three-dimensional assessment of transsacral corridors using artificial intelligence and the planning of transsacral implant positioning. In total, 100 pelvic CTs (49 women, mean age: 58.6 ± SD 14.8 years; 51 men, mean age: 60.7 ± SD 13 years) were used to compute a 3D statistical model of the pelvic ring. On the basis of morphologic features (=predictors) and principal components scores (=response), regression learners were interactively trained, validated, and tuned to predict/sample personalized 3D pelvic models. They were matched via thin-plate spline transformation to a series of 20 pelvic CTs with fragility fractures of the sacrum (18 women and 2 men, age: 69-9.5 years, mean age: 78.65 ± SD 8.4 years). These models demonstrated the availability, dimension, cross-section, and symmetry of transsacral corridors S1 and S2, as well as the planned implant position, dimension, axes, and entry and exit points. The complete intraosseous pathway was controlled in CT reconstructions. We succeeded to establish a workflow determining transsacral corridors S1 and S2 using artificial intelligence and 3D statistical modeling.
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Fracturas Óseas , Huesos Pélvicos , Anciano , Inteligencia Artificial , Tornillos Óseos , Femenino , Fijación Interna de Fracturas/métodos , Humanos , Masculino , Persona de Mediana Edad , Sacro/anatomía & histología , Sacro/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodosRESUMEN
BACKGROUND: A detailed understanding of scaphoid anatomy helps anatomic fracture reduction, and optimal screw position. Therefore, we analysed (1) the size and shape variations of the cartilage and osseous surface, (2) the distribution of volumetric bone mineral density (vBMD) and (3) if the vBMD values differ between a peripheral and a central screw pathway? METHODS: Forty-three fresh frozen hand specimens (17 females, 26 males) were analysed with high-resolution peripheral quantitative computed tomography (HR-pQCT) and dissected to compute a 3D-statistical osseous and cartilage surface model and a 3D-averaged vBMD model of the scaphoid. 3D patterns were analysed using principal component analysis (PCA). vBMD was analysed via averaging HR-pQCT grey values and virtual bone probing along a central and peripheral pathway. RESULTS: (1) PCA displayed most notable variation in length ranging from 1.7 cm (- 2SD) to 2.6 cm (mean) and 3.7 cm (+ 2SD) associated with differences of the width and configuration of the dorsal surface (curved and narrow (4 mm) to a wider width (9 mm)). (2) High vBMD was located in the peripheral zone. Lowest vBMD was observed in the centre and waist. (3) Virtual probing along a peripheral pathway near to the cartilage surfaces for the capitate and lunate allowed the center region to be bypassed, resulting in increased vBMD compared to a central pathway. CONCLUSION: High anatomical variations regarding the osseous and cartilage surfaces were associated with three distinct concentrically arranged zones with notable different vBMD. The complex scaphoid anatomy with its waist might alter the strategy of fracture fixation, education and research.
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Densidad Ósea , Tornillos Óseos , Fijación de Fractura/métodos , Imagenología Tridimensional , Hueso Escafoides/anatomía & histología , Hueso Escafoides/cirugía , Tomografía Computarizada por Rayos X/métodos , Femenino , Humanos , Masculino , Hueso Escafoides/diagnóstico por imagen , Hueso Escafoides/metabolismoRESUMEN
Retrograde transpubic screw fixation is a common procedure for the treatment of anterior pelvic ring fractures. With its sparing surgical approach and significant pain relief after screw fixations allowing early mobilisation, it has gained importance especially in the treatment of insufficiency fractures in elderly patients. However, positioning of transpubic screw osteosynthesis is not always possible due to narrowness and curvature of the screw corridor. The aim of the present study was to evaluate availability and length of the screw corridor using a 3D statistical model of the pelvic ring consisting out of 150 uninjured pelves. Virtual bore probes with a diameter of 7.5 mm were analysed as to accessibility, length and grey value distribution in Hounsfield Unit (HU). A transpubic corridor with a diameter of ≥ 7.5 mm was available in 185 of 300 investigated superior pubic rami with mean screw length of 131.7 mm. Accessibility of the screw corridor was higher in males than in females. However, screw length showed no systematic differences between the sexes or ethnicities. Analysis of the grey value distribution demonstrated the strongest bone to be located at the lateral ilium and the supraacetabular region.
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PURPOSE: To analyze orbital morphological parameters that potentially could influence the effect of decompression surgery on exophthalmos reduction in Graves orbitopathy, thus making decompression surgery more predictable. METHODS: To generate a reference database, a CT-based study was performed in 140 orbits obtained from adult patients with unaffected orbits in a European white ethnicity. The following parameters were chosen: orbital volume, globe volume, globe to orbital volume ratio, and orbital cone angle. Volumes were measured on postprocessed CT data using morphometric techniques. To define the cone angle, a 3-dimensional approach was chosen using the program Amira. RESULTS: Significant interindividual variation was found in orbital volume from 18.9 to 33.4 ml and in globe volume from 6.0 to 10.1 ml. The globe to orbital volume ratio showed a relatively broad variation from 0.25 to 0.4. Differences in the orbital cone angle from 39.7° to 65.7° were observed. CONCLUSION: The experienced large variations in orbital morphology might significantly influence the degree of exophthalmos reduction, which can be obtained by standardized decompression procedures. Based on our results, a prospective clinical study will be conducted to test our hypothesis.
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Descompresión Quirúrgica , Exoftalmia/cirugía , Oftalmopatía de Graves/cirugía , Órbita/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Pesos y Medidas Corporales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia , Tomografía Computarizada Espiral , Población Blanca , Adulto JovenRESUMEN
In complex orbital defects, typically the eye globe is retruded in a pathological position. This is associated with severe functional and cosmetic post-traumatic conditions. Characteristically, the posterior orbital floor and the medial wall of the bony orbit (=region of interest, ROI) is fractured where adequate reconstruction is crucial for a satisfactory surgical outcome but difficult to achieve. By introducing the concept of preshaped, navigated orbital implants, the repair of complex orbital fracture patterns could be significantly facilitated and improved. However, this ROI, delineated according to surgical criteria, cannot be defined by distinct anatomical landmarks because of the absence of reliable anatomical features. The determination of homologous surface points therefore remains a problem in such regions. The aim of this study was to provide a method for the assessment of the 3D shape of the ROI and of its variability, respectively. By aligning an anatomically determinable region that embeds the region of interest with a thin plate spline, transformation homology can be determined suitable for subsequent state-of-the-art shape analysis. First results of shape variations are illustrated and give hints into the future of optimized implant design.
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Interpretación de Imagen Asistida por Computador , Imagenología Tridimensional/métodos , Órbita/diagnóstico por imagen , Implantes Orbitales , Lógica Difusa , Humanos , Órbita/cirugía , Fracturas Orbitales/diagnóstico por imagen , Fracturas Orbitales/cirugía , Diseño de Prótesis , Intensificación de Imagen Radiográfica , Sensibilidad y Especificidad , Tomografía Computarizada por Rayos X/métodosRESUMEN
BACKGROUND/OBJECTIVE: Artificial bone models (ABMs) are used in orthopaedics for research of biomechanics, development of implants and educational purposes. Most of the commercially available ABMs approximate the morphology of Europeans, but they may not depict the Asian anatomy. Therefore, our aim was to develop the first Asian ABM of the pelvis and compare it with the existing pelvic ABM (Synbone®; Caucasian male). METHODS: One hundred clinical computed tomography (CTs) of adult pelvises (male n â= â50, female n â= â50) of Malay, Chinese and Indian descent were acquired. CTs were segmented and defined landmarks were placed. Three 3D statistical pelvic model and mean models (overall, male, female) were generated. Anatomical variations were analysed using principal component analysis. To measure gender-related differences and differences to the existing ABM, distances between the anterior superior iliac spines (ASIS), the anterior inferior iliac spines (AIIS), the promontory and the symphysis (conjugate vera, CV) as well as the ischial spines (diameter transversa, DT) were quantified. RESULTS: Principal component analysis displayed large variability regarding the pelvic shape and size. Female and male statistical models were similar in ASIS (225 â± â20; 227 â± â13 âmm; P â= â0.4153) and AIIS (185 â± â11; 187 â± â10 âmm; P â= â0.3982) and differed in CV (116 â± â10; 105 â± â10 âmm; P â< â0.0001) and DT (105 â± â7; 88 â± â8 âmm; P â< â0.0001). Comparing the unisex mean model with the pre-existing ABM, the ASIS (226; 275 âmm; P â< â0.0001), the AIIS (186; 209 âmm; P â< â0.0001) and the CV (111; 105 âmm; P â< â0.0001) differed significantly. Both models were similar regarding DT (97; 95 âmm; P â= â0.6927). The analysis revealed notable gender- and size-dependent anatomical variations within the Asian population. Chinese, Malay and Indian descents did not differ notably. The overall Asian model was smaller than the existing ABM. THE TRANSLATION POTENTIAL OF THIS ARTICLE: Owing to the large differences between the Asian ABM and the pre-existing ABM, as well as differences between genders, the use of an Asian- and gender-specific ABM is important to consider in research, biomechanics and implant development for this population.
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Trans-sacral implants can be used alternatively to sacro-iliac screws in the treatment of osteoporosis-associated fragility fractures of the pelvis and the sacrum. We investigated trans-sacral corridor dimensions, the number of individuals amenable to trans-sacral fixation, as well as the osseous boundaries and shape of the S1 corridor. 3D models were reconstructed from pelvic CT scans from 92 Europeans and 64 Japanese. A corridor of <12 mm was considered critical for trans-sacral implant positioning, and <8 mm as impossible. A statistical model of trans-sacral corridor S1 was computed. The limiting cranio-caudal diameter was 11.6 mm (±5.4) for S1 and 14 mm (±2.4) for S2. Trans-sacral implant positioning was critical in 52% of cases for S1, and in 21% for S2. The S1 corridor was impossible in 26%, with no impossible corridor in S2. Antero-superiorly, the S1 corridor was limited not only by the sacrum but in 40% by the iliac fossa. The statistical model demonstrated a consistent oval shape of the trans-section of corridor S1. Considering the variable in size and shape of trans-sacral corridors in S1, a thorough anatomical knowledge and preoperative planning are mandatory using trans-sacral implants. In critical cases, S2 is a veritable alternative. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2577-2584, 2017.
Asunto(s)
Sacro/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Fijación Interna de Fracturas , Humanos , Imagenología Tridimensional , Masculino , Persona de Mediana Edad , Valores de Referencia , Estudios Retrospectivos , Sacro/anatomía & histología , Sacro/cirugía , Fracturas de la Columna Vertebral/cirugía , Tomografía Computarizada por Rayos XRESUMEN
BACKGROUND CONTEXT: Trans-sacral implants are increasingly used to treat fractures of the sacrum, especially for osteoporosis-associated fragility fractures. However, the complex and highly variable sacral anatomy limits their use. It is still not clear which morphologic characteristics are critical to determine the availability and dimensions of trans-sacral corridors. PURPOSE: This study aims to assess sacral anatomy and its influence on trans-sacral corridors. STUDY DESIGN: This study used a computed tomography (CT)-based three-dimensional (3D) statistical size and shape model of the sacrum with multiple morphometric measurements. MATERIALS AND METHODS: A 3D statistical model was computed using clinical CT data of 92 intact pelvises (mean age 61.5 years). Multiple measurements of the sacrum and the trans-sacral corridors were taken. Descriptive statistics and linear regression were calculated. Shape and size were analyzed using principal component analysis. RESULTS: The limiting craniocaudal diameter of the trans-sacral corridor was 13.1 mm (±5 mm) in S1 and 13.8 mm (±2.4 mm) in S2. In S1, the craniocaudal diameter correlated with larger sacral curvature (SC), pelvic incidence (PI), and cranially located auricular surfaces. The presence of an accessory articulation with L5 was associated with a larger trans-sacral corridor S1. In contrast, the craniocaudal diameter of the S2 corridor correlated with more caudally situated auricular surfaces and lower PI. The sacral shape, as demonstrated by the statistical model, was highly variable, which affected the size and availability of trans-sacral corridor S1. Important determinants of trans-sacral corridor S1 were the craniocaudal position of the auricular surfaces and the shape of the sacral ala, which were influenced by SC, sacral height, and PI. CONCLUSIONS: The human sacrum is highly variable in size and shape. The dimensions of trans-sacral corridors depend on the sacral shape and specific morphologic characteristics. Understanding of morphologic variants helps with preoperative assessments of the trans-sacral corridors. When planning to use trans-sacral implants, because of variable sacral anatomy and dimensions of the trans-sacral corridors, thorough preoperative planning is mandatory.
Asunto(s)
Modelos Estadísticos , Sacro/diagnóstico por imagen , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pelvis/anatomía & histología , Pelvis/diagnóstico por imagen , Región Sacrococcígea/anatomía & histología , Región Sacrococcígea/diagnóstico por imagen , Sacro/anatomía & histología , Tomografía Computarizada por Rayos X/métodosRESUMEN
The surgical fracture fixation of the odontoid process (dens) of the second cervical vertebra (C2/axis) is a challenging procedure, particularly in elderly patients affected by bone loss, and includes screw positioning close to vital structures. The aim of this study was to provide an extended anatomical knowledge of C2, the bone mass distribution and bone loss, and to understand the implications for anterior screw fixation. One hundred and twenty standard clinical quantitative computed tomography (QCT) scans of the intact cervical spine from 60 female and 60 male European patients, aged 18-90 years, were used to compute a three-dimensional statistical model and an averaged bone mass model of C2. Shape and size variability was assessed via principal component analysis (PCA), bone mass distribution by thresholding and via virtual core drilling, and the screw placement via virtual positioning of screw templates. Principal component analysis (PCA) revealed a highly variable anatomy of the dens with size as the predominant variation according to the first principal component (PC) whereas shape changes were primarily described by the remaining PCs. The bone mass distribution demonstrated a characteristic 3D pattern, and remained unchanged in the presence of bone loss. Virtual screw positioning of two 3.5 mm dens screws with a 1 mm safety zone was possible in 81.7% in a standard, parallel position and in additional 15.8% in a twisted position. The approach permitted a more detailed anatomical assessment of the dens axis. Combined with a preoperative QCT it may further improve the diagnostic procedure of odontoid fractures. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2154-2163, 2017.