A Three-Dimensional Morphometrical Study of the Distal Human Femur

1992 ◽  
Vol 206 (3) ◽  
pp. 147-157 ◽  
Author(s):  
M Zoghi ◽  
M S Hefzy ◽  
K C Fu ◽  
W T Jackson
Keyword(s):  
Distal Femur ◽  
Sagittal Plane ◽  
Femoral Condyle ◽  
Three Dimensional ◽  
Distal Portion ◽  
Average Radius ◽  
Anterior Portion ◽  
Circular Arcs ◽  
Straight Line ◽  
Circular Base

The objective of this paper is to present a method to describe the three-dimensional variations of the geometry of the three portions forming the distal part of the human femur: the medial and lateral femoral condyles and the intercondylar fossa. The contours of equally spaced sagittal slices were digitized on the distal femur to determine its surface topography. Data collection was performed using a digitizer system which utilizes low-frequency, magnetic field technology to determine the position and orientation of a magnetic field sensor in relation to a specified reference frame. The generalized reduced gradient optimization method was used to reconstruct the profile of each slice utilizing two primitives: straight-line segments and circular arcs. The profile of each slice within the medial femoral condyle was reconstructed using two circular arcs: posterior and distal. The profile of each slice within the lateral femoral condyle was reconstructed using three circular arcs: posterior, distal and anterior. Finally, the profile of each slice within the intercondylar fossa was reconstructed using two circular arcs: proximal-posterior and anterior, and a distal-posterior straight-line segment tangent to the proximal-posterior circular arc. Combining the data describing the profiles of the different slices forming the distal femur, the posterior portions of each of the medial and lateral femoral condyles were modelled using parts of spheres having an average radius of 20 mm. The anterior portion of the lateral condyle was approximated to a right cylinder having its circular base parallel to the sagittal plane with an average radius of 26 mm. The anterior portion of the intercondylar fossa was modelled using an oblique cylinder having its circular base parallel to the sagittal plane with an average radius of 22 mm. Furthermore, it is suggested that the distal portion of the lateral femoral condyle could be modelled using parts of two oblique cones while the distal portion of the medial femoral condyle could be modelled using a part of a single oblique cone, all cones having their circular bases parallel to the sagittal plane. It is also suggested that the posterior portion of the intercondylar fossa could be modelled using two oblique cones: a proximal cone having its base parallel to the sagittal plane and a distal cone having its base parallel to the frontal plane.

Coarse-To-Fine 3D Randomized Hough Transform for Dim Target Detection

2014 ◽  
Vol 519-520 ◽  
pp. 1040-1045
Author(s):  
Ling Fan
Keyword(s):  
Target Detection ◽  
Hough Transform ◽  
Constant Velocity ◽  
Three Dimensional ◽  
Randomized Hough Transform ◽  
Straight Line ◽  
Memory Complexity ◽  
Coarse To Fine

This paper makes some improvements on Roberts representation for straight line in space and proposes a coarse-to-fine three-dimensional (3D) Randomized Hough Transform (RHT) for the detection of dim targets. Using range, bearing and elevation information of the received echoes, 3D RHT can detect constant velocity target in space. In addition, this paper applies a coarse-to-fine strategy to the 3D RHT, which aims to solve both the computational and memory complexity problems. The validity of the coarse-to-fine 3D RHT is verified by simulations. In comparison with the 2D case, which only uses the range-bearing information, the coarse-to-fine 3D RHT has a better practical value in dim target detection.

Assessment of α-calcium sulfate hemihydrate/nanocellulose composite bone graft material for bone healing in a rabbit femoral condyle model

2021 ◽  
Vol 11 (9) ◽  
pp. 1497-1504
Author(s):  
Jinlong Liu ◽  
Yicai Zhang ◽  
Lin Qiu ◽  
Yujuan Zhang ◽  
Bin Gao
Keyword(s):  
Bone Graft ◽  
Calcium Sulfate ◽  
Biological Activities ◽  
Femoral Condyle ◽  
Three Dimensional ◽  
Graft Material ◽  
Bone Graft Material ◽  
Calcium Sulfate Hemihydrate ◽  
Composite Bone

The material properties of nanocellulose (NC) can effectively enhance the structural stability of composite materials. However, the research related to NC/α-calcium sulfate hemihydrate (CSH) composites is largely lacking. In this paper, we explore the combination of these two materials and determine their elaborate biological activities in vivo. Using α-CSH as the matrix, the composite bone graft materials were produced according to different proportions of NC. Then the mechanical strength of the composite bone graft was measured, and the results were analyzed by X-ray diffraction and scanning electron microscopy (SEM). To conduct the material in vivo evaluation, 0% (CN0) and 0.75% (CN0.75) NC/α-CSH composite bone graft materials were implanted into a femoral condyle defect model. The results indicated that NC could significantly enhance the mechanical properties of α-CSH. The SEM analysis indicated that the NC shuttled between the crystal gaps and formed a three-dimensional network structure, which was firmly combined with the crystal structure. Meanwhile, the CN0.75 scaffold remained at 12 weeks postoperation, which provided a long-term framework for new bone formation. Overall, our findings demonstrate that, with a 0.75% NC/α-CSH composite demonstrating good potential as a bone graft material for clinical bone grafting.

scholarly journals Surgical management of complex intra-articular distal femoral and bicondylar Hoffa fracture

2016 ◽  
Vol 98 (8) ◽  
pp. e168-e170 ◽  
Author(s):  
D Giotikas ◽  
M Nabergoj ◽  
M Krkovic
Keyword(s):  
Distal Femur ◽  
Sagittal Plane ◽  
Distal Humerus ◽  
Complex Case ◽  
Parallel Plates ◽  
Stable Fixation ◽  
Range Of Movement ◽  
Left Femur ◽  
Hoffa Fracture ◽  
Metaphyseal Fracture

Bicondylar Hoffa’s fractures of distal femur are rare. We report the case of an 18-year-old male who sustained a closed complex fracture of both femoral condyles of the left femur on the sagittal plane (Hoffa fracture), combined with distal metaphyseal fracture. He was treated using parallel plates and interdigitating screws, with our technique based on an extrapolation of the principles of distal humerus fixation. The fracture united clinically and radiologically at 16 weeks. Twelve months postoperatively, the range of movement in the knee was 5°–115°. In this complex case, our technique provided stable fixation of the fragments and a satisfactory final functional outcome.

scholarly journals Three-Dimensional (3-D) Immersed-Boundary (IB) Based Tornado Model for Computational Analysis of Disastrous Wind Load on Buildings

2021 ◽  
Author(s):  
Xixiong Guo ◽  
Jun Cao
Keyword(s):  
Wind Field ◽  
High Speed ◽  
Outer Boundary ◽  
Three Dimensional ◽  
Influence Factors ◽  
Research Direction ◽  
Wind Loading ◽  
Immersed Boundary ◽  
Design Strategies ◽  
Straight Line

This study is aimed at developing a novel computational framework that can essentially simulate a tornadic wind field and investigate the wind loadings on ground constructions. It is well known that tornado is a highly turbulent airflow that simultaneously translates, rotates and updrafts with a high speed. Tornadoes induce a significantly elevated level of wind forces if compared to a straight-line wind. A suitably designed building for a straight-line wind would fail to survive when exposed to a tornadic-like wind of the same wind speed. It is necessary to design buildings that are more resistant to tornadoes. Since the study of tornado dynamics relying on field observations and laboratory experiments is usually expensive, restrictive, and time-consuming, computer simulation mainly via the large eddy simulation (LES) method has become a more attractive research direction in shedding light on the intricate characteristics of a tornadic wind field. For numerical simulation of a tornado-building interaction scenario, it looks quite challenging to seek a set of physically-rational and meanwhile computationally-practical boundary conditions to accompany traditional CFD approaches; however, little literature can be found, as of today, in three-dimensional (3D) computational tornado dynamics study. Inspired by the development of the immersed boundary (IB) method, this study employed a re-tailored Rankine-combined vortex model (RCVM) that applies the “relative motion” principle to the translational component of tornado, such that the building is viewed as “virtually” translating towards a “pinned” rotational flow that remains time-invariant at the far field region. This revision renders a steady-state kinematic condition applicable to the outer boundary of a large tornado simulation domain, successfully circumventing the boundary condition updating process that the original RCVM would have to suffer, and tremendously accelerating the computation. Wind loading and its influence factors are comprehensively investigated and analyzed both on a single building and on a multiple-building configuration. The relation between the wind loadings and the height and shape of the building is also examined in detail. Knowledge of these loadings may lead to design strategies that can enable ground construction to be more resistant to tornadoes, reducing the losses caused by this type of disastrous weather.

scholarly journals A Novel Technique to Assess Rotational Deformities in Lower Extremities

2020 ◽  
Author(s):  
Peyman Bakhshayesh ◽  
Ugwunna Ihediwa ◽  
Sukha Sandher ◽  
Alexandros Vris ◽  
Nima Heidari ◽  
...  
Keyword(s):  
Moving Objects ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Contralateral Side ◽  
Ct Images ◽  
New Technique ◽  
X Rays ◽  
Digital Technique ◽  
The Right ◽  
Im Nailing

Abstract Introduction: Rotational deformities following IM nailing of tibia has a reported incidence of as high as 20%. Common techniques to measure deformities following IM nailing of tibia are either based on clinical assessment, plain X-rays or CT-scan comparing the treated leg with the uninjured contralateral side. All these techniques are based on examiners manual calculation inherently subject to bias. Following our previous rigorous motion analysis and symmetry studies on hemi pelvises, femurs and orthopaedic implants, we aimed to introduce a novel fully digital technique to measure rotational deformities in the lower legs.Material and Methods: Following formal institutional approval from the Imperial College, CT images of 10 pairs of human lower legs were retrieved. Images were anonymized and uploaded to a research server. Three dimensional CT images of the lower legs were bilaterally reconstructed. The mirrored images of the left side were merged with the right side proximally as stationary and distally as moving objects. Discrepancies in translation and rotation were automatically calculated.Results: Our study population had a mean age of 54 ± 20 years. There were six males and four females. We observed a greater variation in translation (mm) of Centre of Mass (COM) in sagittal plane (CI: -2.959--.292) which was also presented as rotational difference alongside the antero-posterior direction or Y axis (CI: .370-1.035). In other word the right lower legs in our study were more likely to be in varus compared to the left side. However, there were no statistically significant differences in coronal or axial planes.Conclusion: Using our proposed fully digital technique we found that lower legs of the human adults were symmetrical in axial and coronal plane. We found sagittal plane differences which need further addressing in future using bigger sample size. Our novel recommended technique is fully digital and commercially available. This new technique can be useful in clinical practice addressing rotational deformities following orthopaedic surgical intervention. This new technique can substitute the previously introduced techniques.

scholarly journals Comparing Locking Screw Direction Among Three Locking Plates for Lateral Clavicle Fractures: A Simulation Study

2020 ◽  
Author(s):  
Shingo Abe ◽  
Kota Koizumi ◽  
Toshiki Shimada ◽  
Tsuyoshi Murase ◽  
Kohji Kuriyama
Keyword(s):  
Sagittal Plane ◽  
Fragment Size ◽  
Three Dimensional ◽  
Locking Plates ◽  
Distal Clavicle ◽  
Inferior Surface ◽  
Locking Screws ◽  
Lateral Clavicle ◽  
The Usa ◽  
Clavicle Fractures

Abstract BackgroundThe current study aimed to measure screw angles of three locking plates for lateral clavicle fractures and to assess the numbers of screws that could be inserted per fragment size to elucidate the size limitation that could be fixed by locking plates.MethodsThe authors assessed three locking plates for lateral clavicle fractures: distal clavicle plate [Acumed, LLC, Oregon, the USA], LCP clavicle plate lateral extension [Depuy Synthes, LLC, MA, the USA], and HAI clavicle plate [HOMS Engineering, Inc., Nagano, Japan]. Using three-dimensional plate models, the angles between the most medial and lateral locking screws on the coronal plane and between the most anterior and posterior locking screws on the sagittal plane were measured. Two examiners independently performed computer simulation to position the plates as laterally as possible in the ten normal three-dimensional clavicle models. A lateral fragment size of 10, 15, 20, 25, and 30 mm was simulated in the acromioclavicular joint and the number of screws completely inserted in each size of the fragment in the simulation was assessed. Subsequently, the area covered by locking screws on the inferior surface of the clavicle was measured.ResultsThe distal clavicle plate had relatively large screw angles (20° on the coronal plane and 32° on the sagittal plane), and the LCP clavicle lateral extension had a large angle (38°) on the sagittal plane. However, the angle of the HAI clavicle plate was at maximum 13° on the coronal or sagittal plane. The distal clavicle plate indicated the largest numbers of screws that could be inserted in each size of the bone fragment. For all locking plates, all screws could be inserted within 25 mm fragments. Among all locking plates, the distal clavicle plate could cover the largest area on the inferior surface of the clavicle by the screws.ConclusionsScrew angles and the numbers of screws that could be inserted in the lateral fragment differed among products. Other augmented fixation procedures should be considered for fractures with fragment sizes <25 mm that could not be fixed with sufficient number of screws.

scholarly journals Competitive and Recreational Running Kinematics Examined Using Principal Components Analysis

Healthcare ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1321
Author(s):  
Wenjing Quan ◽  
Huiyu Zhou ◽  
Datao Xu ◽  
Shudong Li ◽  
Julien S. Baker ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Principal Components ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Frontal Plane ◽  
Principal Component ◽  
Component Analysis ◽  
Ankle Inversion ◽  
Motion System ◽  
Recreational Runners

Kinematics data are primary biomechanical parameters. A principal component analysis (PCA) of waveforms is a statistical approach used to explore patterns of variability in biomechanical curve datasets. Differences in experienced and recreational runners’ kinematic variables are still unclear. The purpose of the present study was to compare any differences in kinematics parameters for competitive runners and recreational runners using principal component analysis in the sagittal plane, frontal plane and transverse plane. Forty male runners were divided into two groups: twenty competitive runners and twenty recreational runners. A Vicon Motion System (Vicon Metrics Ltd., Oxford, UK) captured three-dimensional kinematics data during running at 3.3 m/s. The principal component analysis was used to determine the dominating variation in this model. Then, the principal component scores retained the first three principal components and were analyzed using independent t-tests. The recreational runners were found to have a smaller dorsiflexion angle, initial dorsiflexion contact angle, ankle inversion, knee adduction, range motion in the frontal knee plane and hip frontal plane. The running kinematics data were influenced by running experience. The findings from the study provide a better understanding of the kinematics variables for competitive and recreational runners. Thus, these findings might have implications for reducing running injury and improving running performance.

Lower Extremity Joint Work During Acceleration, Deceleration, and Steady State Running

2017 ◽  
Vol 33 (1) ◽  
pp. 56-63 ◽  
Author(s):  
D.S. Blaise Williams ◽  
Jonathan H. Cole ◽  
Douglas W. Powell
Keyword(s):  
Steady State ◽  
Lower Extremity ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Joint Work ◽  
Negative Work ◽  
Relative Contribution ◽  
Acceleration And Deceleration ◽  
The Individual ◽  
Positive Work

Running during sports and for physical activity often requires changes in velocity through acceleration and deceleration. While it is clear that lower extremity biomechanics vary during these accelerations and decelerations, the work requirements of the individual joints are not well understood. The purpose of this investigation was to measure the sagittal plane mechanical work of the individual lower extremity joints during acceleration, deceleration, and steady-state running. Ten runners were compared during acceleration, deceleration, and steady-state running using three-dimensional kinematics and kinetics measures. Total positive and negative joint work, and relative joint contributions to total work were compared between conditions. Total positive work progressively increased from deceleration to acceleration. This was due to greater ankle joint work during acceleration. While there was no significant change in total negative work during deceleration, there was a greater relative contribution of the knee to total negative work with a subsequent lower relative ankle negative work. Each lower extremity joint exhibits distinct functional roles in acceleration compared with deceleration during level running. Deceleration is dominated by greater contributions of the knee to negative work while acceleration is associated with a greater ankle contribution to positive work.

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