scholarly journals Variation of the Three-Dimensional Femoral J-Curve in the Native Knee

2021 ◽  
Vol 11 (7) ◽  
pp. 592
Author(s):  
Sonja A. G. A. Grothues ◽  
Klaus Radermacher
Keyword(s):  
Geometric Parameter ◽  
Knee Kinematics ◽  
Size Variation ◽  
Principal Component ◽  
Parameter Analysis ◽  
Patient Specific ◽  
3D Analysis ◽  
Relative Location ◽  
Shape Variation ◽  
J Curve

The native femoral J-Curve is known to be a relevant determinant of knee biomechanics. Similarly, after total knee arthroplasty, the J-Curve of the femoral implant component is reported to have a high impact on knee kinematics. The shape of the native femoral J-Curve has previously been analyzed in 2D, however, the knee motion is not planar. In this study, we investigated the J-Curve in 3D by principal component analysis (PCA) and the resulting mean shapes and modes by geometric parameter analysis. Surface models of 90 cadaveric femora were available, 56 male, 32 female and two without respective information. After the translation to a bone-specific coordinate system, relevant contours of the femoral condyles were derived using virtual rotating cutting planes. For each derived contour, an extremum search was performed. The extremum points were used to define the 3D J-Curve of each condyle. Afterwards a PCA and a geometric parameter analysis were performed on the medial and lateral 3D J-Curves. The normalized measures of the mean shapes and the aspects of shape variation of the male and female 3D J-Curves were found to be similar. When considering both female and male J-Curves in a combined analysis, the first mode of the PCA primarily consisted of changes in size, highlighting size differences between female and male femora. Apart from changes in size, variation regarding aspect ratio, arc lengths, orientation, circularity, as well as regarding relative location of the 3D J-Curves was found. The results of this study are in agreement with those of previous 2D analyses on shape and shape variation of the femoral J-Curves. The presented 3D analysis highlights new aspects of shape variability, e.g., regarding curvature and relative location in the transversal plane. Finally, the analysis presented may support the design of (patient-specific) femoral implant components for TKA.

scholarly journals Variation of the femoral J-Curve in the native knee

10.29007/5k32 ◽  
2020 ◽  
Author(s):  
Sonja A. G. A. Grothues ◽  
Malte Asseln ◽  
Klaus Radermacher
Keyword(s):  
Principal Component ◽  
Qualitative Evaluation ◽  
Parameter Analysis ◽  
Implant Design ◽  
J Curve ◽  
Individual Variations ◽  
History Of ◽  
Total Knee ◽  
The Individual ◽  
Standard Implant

The J-Curve in the native knee as well as the femoral component’s J-Curve after total knee arthroplasty are known to have a high influence on kinematics. Furthermore, the J-Curve’s shape affects ligament strain and tension and consequently already slight changes may strongly alter knee forces and stability. To optimize current implants’ J-Curve design with regard to the population’s morphology, information about the main sources of contour variation is necessary.In this study, a principal component analysis (PCA) was performed on the medial and lateral femoral J-Curves of 90 cadavers without history of osteoarthritis. The J-Curves’ mean shapes were further investigated by geometric parameter analysis and effect sizes were calculated for the first three principal components (PCs). In addition, a combined PCA for both sides was performed and evaluated qualitatively. The results were compared with the variation in standard implants’ J-Curve shape.The isolated PCA of medial and lateral J-Curves resulted in PCs involving changes in contour orientation, arc length, scaling and circularity. The combined PCA of both sides resulted in PCs comprising combinations of the individual variations together with changes in relative position. In contrast, the qualitative evaluation of J-Curves from 2 different standard implant systems revealed no visible changes in shape but only changes in size.Limitations of this study were the restriction to a 2-dimensional contour derivation and the sole consideration of the femoral contours. Nevertheless, the sagittal variability in the medial, lateral and combined femoral J-Curves should be considered in implant design.

An empirical evaluation of several univariate methods that adjust for size variation in morphometric data

1985 ◽  
Vol 63 (6) ◽  
pp. 1429-1439 ◽  
Author(s):  
James D. Reist
Keyword(s):  
Empirical Evaluation ◽  
Size Variation ◽  
Covariance Structure ◽  
Principal Component ◽  
Major Axis ◽  
Complete Removal ◽  
Shape Variation ◽  
Standard Size ◽  
Data Set ◽  
Regression Slopes

A variety of univariate transformations that attempt to separate size and shape variation are available: logarithms, ratios, logarithms of ratios, allometric adjustment, and regression techniques (major axis, residuals). Using the same basic data set derived from morphometric measurements of a freshwater fish, these transformations were examined for their effects upon variable distributions, correlations, and covariances. Those that were at least partly effective in removing size variation affected the correlation and covariance structure of the data in different ways, and thus resulted in different biological interpretations for principal component and discriminant analyses. Adjustment of size using a regression technique (computation of residuals from a standard size axis) or allometric adjustment to a standard size was preferred because these allowed for the complete removal of size variation and adverse effects were minimal. Although the actual estimates of shape were different for these two transformations, the relationships that resulted between groups inherent in the data were very similar. If heterogeneity between samples exists in the regression slopes or the allometric coefficients, the common within-groups slope or coefficient must be used to adjust for size.

scholarly journals A feasibility study of a novel, task-specific movement training intervention for women with patellofemoral pain

2017 ◽  
Vol 32 (2) ◽  
pp. 179-190 ◽  
Author(s):  
Gretchen B Salsich ◽  
Barbara Yemm ◽  
Karen Steger-May ◽  
Catherine E Lang ◽  
Linda R Van Dillen
Keyword(s):  
Weight Bearing ◽  
Knee Kinematics ◽  
Frontal Plane ◽  
Patellofemoral Pain ◽  
Patient Specific ◽  
Training Intervention ◽  
Specific Training ◽  
Intervention Effects ◽  
And Function ◽  
Treatment Credibility

Objective: To investigate whether a novel, task-specific training intervention that focused on correcting pain-producing movement patterns was feasible and whether it would improve hip and knee kinematics, pain, and function in women with patellofemoral pain. Design: Prospective, non-randomized, within-group, double baseline, feasibility intervention study. Subjects: A total of 25 women with patellofemoral pain were enrolled. Intervention: The intervention, delivered 2×/week for six weeks, consisted of supervised, high-repetition practice of daily weight-bearing and recreational activities. Activities were selected and progressed based on participants’ interest and ability to maintain optimal alignment without increasing pain. Main measures: Primary feasibility outcomes were recruitment, retention, adherence, and treatment credibility (Credibility/Expectancy Questionnaire). Secondary outcomes assessing intervention effects were hip and knee kinematics, pain (visual analog scale: current, average in past week, maximum in past week), and function (Patient-Specific Functional Scale). Results: A total of 25 participants were recruited and 23 were retained (92% retention). Self-reported average daily adherence was 79% and participants were able to perform their prescribed home program correctly (reduced hip and knee frontal plane angles) by the second intervention visit. On average, treatment credibility was rated 25 (out of 27) and expectancy was rated 22 (out of 27). Hip and knee kinematics, pain, and function improved following the intervention when compared to the control phase. Conclusion: Based on the feasibility outcomes and preliminary intervention effects, this task-specific training intervention warrants further investigation and should be evaluated in a larger, randomized clinical trial.

Functional Evaluation of a Personalized Orthosis for Knee Osteoarthritis - A Motion Capture Analysis

2021 ◽  
Author(s):  
Martin Huber ◽  
Matthew Eschbach ◽  
Kazem Kazerounian ◽  
Horea T. Ilies
Keyword(s):  
Knee Joint ◽  
Knee Osteoarthritis ◽  
Motion Capture ◽  
Inverse Dynamics ◽  
Statistical Significance ◽  
Knee Kinematics ◽  
Contact Forces ◽  
Patient Specific ◽  
Functional Evaluation ◽  
Shock Absorption

Abstract Knee osteoarthritis (OA) is a disease that compromises the cartilage inside the knee joint, resulting in pain and impaired mobility. Bracing is a common treatment, however currently prescribed braces cannot treat bicompartmental knee OA, fail to consider the muscle weakness that typically accompanies the disease, and utilize hinges that restrict the knee's natural biomechanics. We have developed and evaluated a brace which addresses these shortcomings. This process has respected three principal design goals: reducing the load experienced across the entire knee joint, generating a supportive moment to aid the muscles in shock absorption, and interfering minimally with gait kinematics. Load reduction is achieved via the compression of medial and lateral leaf springs, and magnetorheological dampers provide the supportive moment during knee loading. A novel, personalized joint mechanism replaces a traditional hinge to reduce interference with knee kinematics. Using motion capture gait analysis, we evaluated the basic functionality of a prototype device. We calculated, via inverse dynamics analysis, the reaction forces at the knee joint and the moments generated by the leg muscles during gait. Comparing these values between braced and unbraced trials allowed us to evaluate the system's effectiveness. Kinematic measurements showed the extent to which the brace interfered with natural gait characteristics. Of the three design goals: a reduction in knee contact forces was demonstrated; increased shock absorption was observed, but not to statistical significance; and natural gait was largely preserved. The techniques presented in this paper could lead to improved OA treatment through patient-specific braces.

scholarly journals Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

2019 ◽  
Author(s):  
Vera Weisbecker ◽  
Thomas Guillerme ◽  
Cruise Speck ◽  
Emma Sherratt ◽  
Hyab Mehari Abraha ◽  
...  
Keyword(s):  
Individual Variation ◽  
Principal Component ◽  
Individual Variability ◽  
Shape Variation ◽  
Mandibular Ramus ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Marsupial Species ◽  
Masticatory System ◽  
The Individual

AbstractBackgroundWithin-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, shape variation should not be dominated by allometry; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues.ResultsWe assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of thre species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus.DiscussionOur results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraint act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

Abstract 12471: Optimal Prediction of Atrial Fibrillation Recurrence After Ablation: A Computational Anatomy Study

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Marta Varela ◽  
Felipe Bisbal ◽  
Ernesto Zacur ◽  
Esther Guiu ◽  
Antonio Berruezo ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrial ◽  
Complete Characterization ◽  
Statistical Shape Model ◽  
Patient Specific ◽  
Shape Variation ◽  
Global Features ◽  
Linear Discriminant ◽  
Af Ablation ◽  
Statistical Shape

Background: Left atrial structural remodelling, assessed by left atrial (LA) sphericity or antero-posterior diameter, has been shown to predict recurrence after atrial fibrillation (AF) ablation. The study aimed to perform a computational shape analysis of the LA to quantitatively characterise the LA shape remodelling process and identify metrics that optimally predict recurrence. Methods: Pre-procedural bright-blood MRIs of the LA of patients undergoing AF ablation were segmented. Patient-specific smooth 3D meshes were fitted to the segmentations. A statistical shape model of the LA was created and the global features underpinning the observed shape variation extracted as principal components (PCs). PCs were optimally combined to create non-empirical atlas-based metrics using linear discriminant analysis. Meshes depicting mean and extreme recurrent and non-recurrent LA shapes were also synthetized. The capability of different metrics to predict recurrence was evaluated using the area under the ROC curve (AUC) of a leave 1 out cross validation test. Results: In total, 111 patients were included. At 12 months follow-up, LA sphericity was the best predictor of recurrence (AUC: 0.66) over novel atlas-based metrics (AUC: 0.65). At 24 months, atlas-based metrics were the best predictors of recurrence (AUC: 0.66), outperforming a combination of sphericity and volume (AUC: 0.64), sphericity alone (AUC: 0.63) and any other traditional metric. Conclusions: Novel atlas-based metrics improve the prediction of recurrence at 2 years post-AF ablation. They allow a more complete characterization of the LA shape remodelling process, for example by allowing the synthesis of recurrent and non-recurrent LA shapes, which may contribute to patient stratification for AF ablation.

scholarly journals Positional variation rather than salt stress dominates changes in three-dimensional leaf shape patterns in cucumber canopies

2019 ◽  
Author(s):  
Dominik Schmidt ◽  
Katrin Kahlen
Keyword(s):  
Salt Stress ◽  
Stress Responses ◽  
Leaf Shape ◽  
Three Dimensional ◽  
Size Variation ◽  
Canopy Architecture ◽  
Shape Variation ◽  
Stress Study ◽  
Salinity Levels ◽  
Adaptation Processes

Abstract Leaf shape plays a key role in the interaction of a plant with its environment, best-known in the plant’s light harvest. Effects of the environment on the interplay of canopy architecture and physiological functioning can be estimated using functional-structural plant models (FSPMs). In order to reduce the complexity of canopy simulations, leaf shape models used in FSPMs are often simple prototypes scaled to match current leaf area. L-Cucumber is such an FSPM, whose leaf prototype mimics average real leaf shape of unstressed cucumber plants well. However, adaptation processes or stress responses may lead to non-proportional changes in leaf geometries, which, for example, could affect length to width ratios or curvatures. The current leaf shape model in L-Cucumber is static and hence does not incorporate changes in leaf shape within or between plants. Thus, the aim of this study was to estimate leaf shape variation and exemplarily study its effects on FSPM simulations. Three-dimensional leaf coordinate data from a salt stress study were analysed with a robust Bayesian mixed-effects model for estimating leaf shape depending on rank, size and salinity. Results showed that positional and size variation rather than salinity levels dominated 3D leaf shape patterns of cucumber. Considering variable leaf shapes in relation to this main sources of variation in L-Cucumber simulations, only minor effects compared to a realistic, yet static average shape were found. However, with similar computational demands variation in shapes other studies highly sensitive to shape dynamics, for example, pesticide spraying might be affected more strongly.

scholarly journals Morphological Divergence of Snow Trout (Schizothorax Richardsonii, Gray 1932) from Rivers of Nepal with Insights from a Morphometric Analysis

2015 ◽  
Vol 3 (3) ◽  
pp. 464-473
Author(s):  
Suresh Kumar Wagle ◽  
Neeta Pradhan ◽  
Madhav Kumar Shrestha
Keyword(s):  
Size Variation ◽  
Principal Component ◽  
Head Region ◽  
Body Depth ◽  
Morphometric Characters ◽  
Significant Difference ◽  
Snow Trout ◽  
Major River ◽  
Mean Vectors ◽  
Schizothorax Richardsonii

Asala or snow trout (Schizothorax richardsonii, Cyprinidae), one of highly valued freshwater fish of Transhimalayan regions, is distributed in upper reaches of all major river systems of Nepal. Morphometric diversification between six river populations of S. richardsonii was examined to identify intraspecific unit for enabling better management of the resources. Significant differences were observed in 17 measured morphometric characters of 207 specimens among the six river populations. Multivariate analysis of variance (Wilks' test) indicated a significant difference for mean vectors of mophometric measurements (? =0.012, F85, 731 = 19.999, P<0.0001) among populations. Principal component and discriminant functions (DFs) analysis of morphometric measurements revealed high seperation of the stocks. The analysis showed that most of the shape and size variation among these populations occurs in the head region, body depth and fin length. Apparent morphometric divergence among S. richardsonii samples showed the existence of three differentiated groups viz., the Indrawati and Khudi populations, the Melamchi and Phalaku Rivers, and the Sabha and Tadi River populations of Nepal. The results of this study may be useful in fisheries management and potential exploitation of this species in coldwater aquaculture.Int J Appl Sci Biotechnol, Vol 3(3): 464-473

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