Three-dimensional Optical Scanning Research Articles

Diagnostic and treatment possibilities in the management of positional plagiocephaly.

Positional plagiocephaly, characterized by an asymmetric skull shape, is the most common craniofacial malformation in infancy. Associated risk factors include apreference for the supine position, first and assisted delivery, multiple pregnancy, prematurity, and congenital muscular torticollis. The diagnosis is established by clinical and anthropometric examinations. In the case of moderate or severe deformity, three-dimensional optical scanning enables adetailed depiction of the deformity and provides asafe and noninvasive tool for follow-up. Treatment mainly includes repositioning of the infant, while orthotic therapy is considered in cases of severe deformity. Cranial orthotic therapy is most effective when started between 4and 7months of age. The total duration of orthotic treatment ranges from 2to 6months. Although the clinical course of positional plagiocephaly is generally benign and the prognosis favorable, its increasing prevalence has prompted the development of novel diagnostic and therapeutic strategies over the past decade.

Investigate on the mechanical properties and microscopic three-dimensional morphology of rock failure surfaces under different stress states

The macro and micro morphology of rock failure surfaces play crucial roles in determining the rock mechanical and seepage properties. The morphology of unloaded deep rock failure surfaces exhibits significant variability and complexity. Surface roughness is closely linked to both shear strength and crack seepage behavior. Understanding these morphology parameters is vital for comprehending the mechanical behavior and seepage characteristics of rock masses. In this study, three-dimensional optical scanning technology was employed to analyze the micromorphological properties of limestone and sandstone failure surfaces under varying stress conditions. Line and surface roughness characteristics of different rock failure surfaces were then determined. Our findings reveal a critical confining pressure value (12 MPa) that influences the damage features of Ordovician limestone failure surfaces. With increasing confining pressure, pore depth and crack formation connecting the pores also increase. Beyond the critical confining pressure, the mesoscopic roughness of the failure surface decreases, and the range of interval-distributed pore roughness diminishes. Additionally, we conducted a detailed investigation into the water conductivity properties of rocks under different stress states using Barton's joint roughness coefficient (JRC) index and rock fractal theory. The roughness features of rock failure surfaces were classified into three categories based on mesoscopic pore and crack undulation forms: straight, wavy, and jagged. We also observed significant confining pressure effects on limestone and sandstone, which exceeding the critical confining pressure led to increased water conductivity in both rocks, albeit through different mechanisms. While sandstone exhibits fissures running across it, limestone shows shear abrasion holes. Beyond the critical confining pressure, the rock failure surface becomes smoother, leading to decreased water flow blocking capacity. The fractal dimension of Ordovician limestone increases significantly under critical confining pressure, leading to a more complex mesoscopic crack extension route.

Generative deep learning furthers the understanding of local distributions of fat and muscle on body shape and health using 3D surface scans

BackgroundBody shape, an intuitive health indicator, is deterministically driven by body composition. We developed and validated a deep learning model that generates accurate dual-energy X-ray absorptiometry (DXA) scans from three-dimensional optical body scans (3DO), enabling compositional analysis of the whole body and specified subregions. Previous works on generative medical imaging models lack quantitative validation and only report quality metrics.MethodsOur model was self-supervised pretrained on two large clinical DXA datasets and fine-tuned using the Shape Up! Adults study dataset. Model-predicted scans from a holdout test set were evaluated using clinical commercial DXA software for compositional accuracy.ResultsPredicted DXA scans achieve R2 of 0.73, 0.89, and 0.99 and RMSEs of 5.32, 6.56, and 4.15 kg for total fat mass (FM), fat-free mass (FFM), and total mass, respectively. Custom subregion analysis results in R2s of 0.70–0.89 for left and right thigh composition. We demonstrate the ability of models to produce quantitatively accurate visualizations of soft tissue and bone, confirming a strong relationship between body shape and composition.ConclusionsThis work highlights the potential of generative models in medical imaging and reinforces the importance of quantitative validation for assessing their clinical utility.

The applicability of a commercial 3DO body scanner in measuring body composition in Chinese adults with overweight and obesity: a secondary analysis based on a weight-loss clinical trial.

A commercial three-dimensional optical (3DO) scanning system was reported to be used in body composition assessment. However, the applicability in Chinese adults has yet to be well-studied. This secondary analysis was based on a 16-week weight-loss clinical trial with an optional extension to 24 weeks. Waist and hip circumference and body composition were measured by 3DO scanning at each follow-up visit during the study. Bioelectrical impedance analysis (BIA) was also performed to confirm the reliability of 3DO scanning at each visit. We used Lin's concordance correlation coefficients (CCC) to evaluate the correlation between the two methods above-mentioned. Bland-Altman analysis was also performed to evaluate the agreement and potential bias between different methods. A total number of 70 Chinese adults overweight and obese (23 men and 47 women, aged 31.8 ± 5.8 years) were included in the analysis, which resulted in 350 3DO scans and corresponding 350 BIA measurements. The percent body fat, fat mass, and fat-free mass were 33.9 ± 5.4%, 26.7 ± 4.6 kg, and 50.3 ± 8.7 kg before the trial by 3DO scanning. And they were 30.5 ± 5.8%, 22.5 ± 4.7 kg, and 49.4 ± 8.3 kg after 16 weeks of the trial. Compared with BIA, 3DO scanning performed best in the assessment of fat-free mass (CCC = 0.89, 95%CI: 0.86, 0.90), then followed by fat mass (CCC = 0.76, 95%CI: 0.71, 0.80) and percent body fat (CCC = 0.70, 95%CI: 0.64, 0.75). Subgroup analysis showed that 3DO scanning and BIA correlated better in women than that in men, and correlated better in measuring fat-free mass in participants with larger body weight (BMI ≥28.0 kg/m2) than those with smaller body weight (<28.0 kg/m2). 3DO scanning is an effective technology to monitor changes in body composition in Chinese adults overweight and obese. However its accuracy and reliability in different ethnicities needs further exploration.

Method and Application of Spraying Developer Defect Detection in Three-Dimensional Optical Scanning Measurement Process Based on YOLO v7

Method and Application of Spraying Developer Defect Detection in Three-Dimensional Optical Scanning Measurement Process Based on YOLO v7

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

ObjectivesThis study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.Materials and methodsPatients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.ResultsA total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0–T1 (p = 0.02), T0–T2 (p = 0.03), and T0–T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.ConclusionsWe found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.Clinical relevanceIt is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Experimental characterization of impact damage in foam-core sandwich structures using acoustic emission, optical scanning and X-ray computed tomography techniques

Sandwich structures used in transportation and energy industries are commonly subjected to low-velocity impact in the course of manufacturing, service and maintenance, which can lead to the premature degradation of structural stiffness and strength. A single non-destructive evaluation technique is often difficult to provide a comprehensive assessment on impact damage from online to offline and from visible to invisible. In the present study, acoustic emission (AE), three-dimensional (3D) optical scanning and X-ray computed tomography (CT) techniques are combined to provide a systematic approach for damage characterization of thick foam-core sandwich panels under low-velocity impact. In the tests, the mechanical responses such as force-time and force-displacement curves are obtained from the testing system. The AE technique is adopted to monitor damage initiation and evolution in situ; optical scanning and X-ray computed tomography techniques are used for off-line damage identification and quantification. The results show that the AE signal waveform stream, cumulative counts and cumulative energy correlate well with the mechanical responses of the sandwich panel under the low-velocity impact, enabling capture of valuable information for online damage monitoring. Unlike general cases, the AE signals generated from low-velocity impact are found to be presented in strong bursts of nearly coincident events in the short duration. Therefore, the distributions of AE amplitude and peak frequency between adjacent AE counts are extracted to study the different damage modes and damage mechanisms. The X-ray computed tomography images enable to precisely visualize the fracture behaviors of the PET foam-core inside the sandwich panel in a nondestructive fashion, which evidently supports the AE and optical scanning results. The study is anticipated to demonstrate effectiveness and capability of the proposed experimental methodology for damage detection and characterization on sandwiched composite structures subjected to impact loading.

Automated body composition estimation from device-agnostic 3D optical scans in pediatric populations

Excess adiposity in children is strongly correlated with obesity-related metabolic disease in adulthood, including diabetes, cardiovascular disease, and 13 types of cancer. Despite the many long-term health risks of childhood obesity, body mass index (BMI) Z-score is typically the only adiposity marker used in pediatric studies and clinical applications. The effects of regional adiposity are not captured in a single scalar measurement, and their effects on short- and long-term metabolic health are largely unknown. However, clinicians and researchers rarely deploy gold-standard methods for measuring compartmental fat such as magnetic resonance imaging (MRI) and dual X-ray absorptiometry (DXA) on children and adolescents due to cost or radiation concerns. Three-dimensional optical (3DO) scans are relatively inexpensive to obtain and use non-invasive and radiation-free imaging techniques to capture the external surface geometry of a patient's body. This 3D shape contains cues about the body composition that can be learned from a structured correlation between 3D body shape parameters and reference DXA scans obtained on a sample population. This study seeks to introduce a radiation-free, automated 3D optical imaging solution for monitoring body shape and composition in children aged 5-17. We introduce an automated, linear learning method to predict total and regional body composition of children aged 5-17 from 3DO scans. We collected 145 male and 206 female 3DO scans on children between the ages of 5 and 17 with three scanners from independent manufacturers. We used an automated shape templating method first introduced on an adult population to fit a topologically consistent 60,000 vertex (60k) mesh to 3DO scans of arbitrary scanning source and mesh topology. We constructed a parameterized body shape space using principal component analysis (PCA) and estimated a regression matrix between the shape parameters and their associated DXA measurements. We automatically fit scans of 30 male and 38 female participants from a held-out test set and predicted 12 body composition measurements. The coefficient of determination (R2) between 3DO predicted body composition and DXA measurements was at least 0.85 for all measurements with the exception of visceral fat on 3D scan predictions. Precision error was 1-4 times larger than that of DXA. No predicted variable was significantly different from DXA measurement except for male trunk lean mass. Optical imaging can quickly, safely, and inexpensively estimate regional body composition in children aged 5-17. Frequent repeat measurements can be taken to chart changes in body adiposity over time without risk of radiation overexposure.

Comparison of subcritical crack growth and dynamic fracture propagation in rocks under double-torsion tests

Relaxation and rapid displacement loading tests were performed on five types of rocks to gain a deeper understanding of the differences between subcritical crack growth (SCG) and dynamic fractures. The critical surface energy was obtained by fitting a hyperbolic sine function to the SCG velocities and mechanical energy release rates of the five rocks. The specific SCG range and the dimensions of the fracture process zone (FPZ) were determined via the displacement field of the sample bottom surface provided by digital image correlation. The FPZ lengths of the double-torsion rock samples range from 21.03 mm to 34.10 mm, and the lengths increase with the increasing maximum grain size of the rock type. The FPZ width is between 1.63 mm and 3.46 mm and exhibits a similar variation to that of the FPZ length. A three-dimensional optical scanner was used to obtain the morphologies of the subcritical crack surfaces and the dynamic fracture surfaces. The results show that the roughness of the subcritical crack surface is larger than that of the dynamic fracture surface, and both are positively correlated with the maximum grain size of the rock. The scanning electron microscope images demonstrate the change in the roughness of the crack surface; the subcritical cracks preferentially propagate along the grain boundaries while the dynamic fractures directly cut across crystals with some intergranular fractures.

Influence of Adipose-Derived Stromal Vascular Fraction on Resorption of a Large-Volume Free-Fat Transplant Evaluated Using T3D Optical Scanning

Background and Objectives: The main drawback of lipofilling is fat transplant volume loss, which makes long-term results unreliable. This study’s aim was to assess the influence of an adipose-derived stromal vascular fraction (SVF) on volume retention in large-volume fat grafts. Materials and Methods: A murine model was used for the in vivo evaluation of fat-graft volume changes over 6 months. We used 28 immunocompromised nude NU(NCr)-Foxn1nu mice and human fat tissue as a liposuction by-product. Part of the fat tissue was used for SVF preparation. We created a fat transplant without SVF (SVF-) and with SVF (SVF+) groups. Large-volume grafts were injected above the sacrum and scapula in the same animal. Volume loss was evaluated using three-dimensional optical scanning at 14 days (T1), 3 months (T2), and 6 months (T3) after transplantation. Scans were processed with Artec Studio software to obtain stereolithography files. The volumes were calculated in RapidForm software 2006. Results: The highest volume loss was observed above the scapula at T3 (SVF- 85%; SVF+ 75%). There was a significant difference in volume between SVF-/SVF+ for grafts above the sacrum at T2, with lower loss in SVF+, and the significance became stronger at T3. The difference in volume loss was also significant above the scapula between SVF-/SVF+ at T3. Conclusions: Although we found a beneficial effect of SVF on the long-term survival of large-volume fat tissue transplants, volume loss due to other contributing factors was high.

Clinical metrics and tools for provider assessment and tracking of trigonocephaly.

Quantitative measurements of trigonocephaly can be used to characterize and track this phenotype, which is associated with metopic craniosynostosis. Traditionally, trigonocephaly metrics were extracted from CT scans; however, this method exposes patients to ionizing radiation. Three-dimensional optical scans are another option but are not routinely available in most outpatient settings. Recently, the authors developed semiautomated artificial intelligence algorithms that extract craniometric data from orthogonal 2D photographs. Although 2D photographs are safe, inexpensive, and straightforward to obtain, the accuracy of photograph-based craniometrics in comparison to CT and 3D optical scan correlates has not been established. In this study the authors compared the classification power of 2D photograph-based metrics of trigonocephaly with four CT-based metrics and one 3D optical scan-based metric in a heterogeneous series of patients who presented to an outpatient craniofacial clinic. In this study the authors performed retrospective craniometric analyses of patient 2D photographs, 3D optical scans, and CT scans. Imaging-derived craniometrics include the 2D photograph-based anterior arc angle (AAA2D-photo), anterior-posterior ratio (APR2D-photo), and anterior-middle ratio (AMR2D-photo); the CT-based anterior arc angle (AAACT), metopic index (MICT), endocranial-bifrontal angle (eBFACT), and interfrontal angle (IFACT); and the 3D optical scan-based anterior arc angle (AAA3D-optical). Receiver operating characteristics (ROCs) were used to identify craniometrics strongly descriptive of trigonocephaly. Interrater comparisons were made between paired trigonocephaly measurements obtained from photographs and either CT scans or 3D optical scans. There were 13 photograph-based and CT-based pairs and 22 paired measurements from 2D photographs and 3D optical scans. AAA displayed the strongest classification capacity across all three imaging modalities. Significant agreement was observed between AAACT and AAA2D-photo (intraclass correlation coefficient [ICC] = 0.68 [95% CI 0.24-0.89], p = 0.0035), and AAA3D-optical and AAA2D-photo (ICC = 0.70 [95% CI 0.41-0.87], p < 0.0001). There was no significant correlation between APR2D-photo or AMR2D-photo and conventional CT-based metrics describing longitudinal width ratios (MICT). Photograph-based craniometrics are powerful tools that can be used to quantify the severity of trigonocephaly and exhibit high concordance with standard measurements derived from CT scans and 3D optical scans. The authors developed and freely share a research-use application to calculate trigonocephaly metrics from 2D photographs. Given the availability of digital photography, lack of ionizing radiation, and low cost of photograph-based craniometric derivation, this technique may be useful to supplement routine ambulatory care and objectively track outcomes following treatment.

Blisk With Small Geometry Mistuning and Blend Repair: As-Measured Finite Element Model and Experimental Verification

Abstract This paper presents an “As-Measured Model” (AMM) of a blended blisk, built upon the measurement of the true geometry of the blisk by the three-dimensional optical scanning technology. This high-fidelity model aims to account for the variances of blade frequencies and mode shapes within the real blisk in the presence of both the blend repair and inherent geometry mistuning due to manufacturing, etc. An improved mesh updating strategy is proposed to adapt a seed blisk finite element model (FEM) to the measured geometry. The resultant AMM is therefore able to accurately represent the measured blade-to-blade geometry variances. The classical blade detuning test (BDT) in combination with a novel “correction” procedure is employed to experimentally evaluate the “blade-alone” frequency mistuning pattern in the real blisk. Experimental verification of the AMM demonstrates that it is able to not only capture the blade-alone frequency and mode shape variations due to both the blend and intrinsic blade geometry variances, but also to reproduce the global dynamics of the blended blisk with acceptable accuracy.

A Measurement Solution of Face Gears with 3D Optical Scanning.

Gears are usually measured by the contact metrology method in gear measuring centers or coordinate measuring machines. Recently, three-dimensional (3D) optical scanning, a non-contact metrology method, has been applied in the industry as an advanced measurement technology mainly due to its high efficiency. However, its applications to gears with complicated geometry, such as face gears, are still limited due to its relatively low accuracy and the void of related measurement solutions. In this work, an accurate measurement solution with 3D optical scanning is proposed for the tooth surface deviations of orthogonal face gears. First, point cloud collection is carried out by the 3D scanner. Furthermore, the measurement solution is implemented with a three-stage algorithm by aligning point clouds with the design model. Subsequently, 3D modeling is studied by numbering the points and reconstructing the real tooth surfaces. An example with a measurement experiment and loaded tooth contact analysis is given to show the validity of the proposed method.

A structural health monitoring method proposal based on optical scanning and computational models

This article proposes a method for continuous bridge displacement monitoring combining the dynamic triangulation scanning and load estimation by vehicle image recognition. The vehicle–bridge interaction is a non-stationary dynamic process parameter of high relevance to understanding the static instability behavior of bridges. The knowledge of the load on a bridge in the specific time when its structural spatial coordinates are measured allows correlating the bridge displacement with the effect of vehicle–bridge interaction. The evaluation of such correlation is mandatory in order to verify if the observed bridge displacement is due to the nature of its operation or due to it is presenting structural damage. The proposed method is continuous structural health monitoring method, based on the combination of three approaches evaluated at laboratory environment: (1) a three-dimensional optical scanning system for displacement measurement, (2) a load measurement system for vehicle–bridge interaction assessment, and (3) a two-measurement systems data correlation; to be implemented in bridges at a real environment to collect their historical behavior. Overall, for each approach, the measurement systems’ principles, the laboratory experimental methodology followed, and results obtained are presented.

Three-dimensional optical body shape and features improve prediction of metabolic disease risk in a diverse sample of adults.

This study examined whether body shape and composition obtained by three-dimensional optical (3DO) scanning improved the prediction of metabolic syndrome (MetS) prevalence compared with BMI and demographics. A diverse ambulatory adult population underwent whole-body 3DO scanning, blood tests, manual anthropometrics, and blood pressure assessment in the Shape Up! Adults study. MetS prevalence was evaluated based on 2005 National Cholesterol Education Program criteria, and prediction of MetS involved logistic regression to assess (1) BMI, (2) demographics-adjusted BMI, (3) 85 3DO anthropometry and body composition measures, and (4) BMI + 3DO + demographics models. Receiver operating characteristic area under the curve (AUC) values were generated for each predictive model. A total of 501 participants (280 female) were recruited, with 87 meeting the criteria for MetS. Compared with the BMI model (AUC=0.819), inclusion of age, sex, and race increased the AUC to 0.861, and inclusion of 3DO measures further increased the AUC to 0.917. The overall integrated discrimination improvement between the 3DO + demographics and the BMI model was 0.290 (p < 0.0001) with a net reclassification improvement of 0.214 (p < 0.0001). Body shape measures from an accessible 3DO scan, adjusted for demographics, predicted MetS better than demographics and/or BMI alone. Risk classification in this population increased by 29% when using 3DO scanning.

3D printed cranioplasty moulds and a 3D optical scanner: A novel approach to reconstruction of challenging post-traumatic defects

ObjectiveTo describe and assess two cases of a delayed post-traumatic recontouring of the frontal bone using a novel technique. Materials and methodsUsing rapid prototyping, patient specific sterilisable moulds were constructed from mirrored intact contralateral anatomy. The moulds were used intraoperatively to contour calcium phosphate cement at the bone defect. The accuracy of reconstruction was evaluated post operatively through comparisons of planned and actual reconstruction data from a three-dimensional optical scanner. ResultsThe contour of both defects was well restored clinically and there was no significant difference between the computer planned reconstructions and the actual reconstructions, with a mean difference of 0.4 cm3. ConclusionSupraorbital rim disruption, commonly associated with fracture of the frontal bone, can be difficult to reconstruct aesthetically. This technique is a time-efficient and accurate way to reconstruct three-dimensional facial anatomy.

Automated Geometric Imperfection Detection and Quantification of CFS Members from Point Clouds

Cold-formed steel (CFS) has become widely used as a construction material in the last decade. Many studies have been performed to investigate the behaviour of CFS members as individual structural components. The results obtained from these studies showed that CFS members' behaviour under certain loading cases is significantly affected by the geometric imperfections present on these members. To fully understand an individual CFS member's behaviour, the effects of geometric imperfection should be taken into account. However, locating and quantifying these geometric imperfections on any CFS member is not straightforward. In this research, geometric imperfections are- detected automatically using a novel methodology. This method relies on the usage of a three-dimensional optical scanner for collecting texture-mapped point clouds of various C- and omega-sectioned CFS members. CFS members' local and global geometric imperfections are then extracted from the captured texture-mapped point clouds. The obtained results are then compared with the literature. It is observed that the geometric imperfection distributions at both local and global levels on CFS members differ significantly along each member. This differentiation is observed even for the identically dimensioned members manufactured in succession using the same machine.

What Is a 2021 Reference Body?

The historical 1975 Reference Man is a ‘model’ that had been used as a basis for the calculation of radiation doses, metabolism, pharmacokinetics, sizes for organ transplantation and ergonomic optimizations in the industry, e.g., to plan dimensions of seats and other formats. The 1975 Reference Man was not an average individual of a population; it was based on the multiple characteristics of body compositions that at that time were available, i.e., mainly from autopsy data. Faced with recent technological advances, new mathematical models and socio-demographic changes within populations characterized by an increase in elderly and overweight subjects a timely ‘state-of-the-art’ 2021 Reference Body are needed. To perform this, in vivo human body composition data bases in Kiel, Baton Rouge, San Francisco and Honolulu were analyzed and detailed 2021 Reference Bodies, and they were built for both sexes and two age groups (≤40 yrs and >40 yrs) at BMIs of 20, 25, 30 and 40 kg/m2. We have taken an integrative approach to address ‘structure–structure’ and ‘structure–function’ relationships at the whole-body level using in depth body composition analyses as assessed by gold standard methods, i.e., whole body Magnetic Resonance Imaging (MRI) and the 4-compartment (4C-) model (based on deuterium dilution, dual-energy X-ray absorptiometry and body densitometry). In addition, data obtained by a three-dimensional optical scanner were used to assess body shape. The future applications of the 2021 Reference Body relate to mathematical modeling to address complex metabolic processes and pharmacokinetics using a multi-level/multi-scale approach defining health within the contexts of neurohumoral and metabolic control.

Numerical Methods for Calculating Component Modes for Geometric Mistuning Reduced-Order Models

AbstractGeometric mistuning models formulated from component mode synthesis methods often require the calculation of component modes, particularly constraint and fixed interface normal modes (FINMs), during substructuring. For integrally bladed rotors, these calculations are required for each sector. This paper proposes methods that reuse information garnered from solving the constraint modes of a single sector on the remaining sectors to reduce memory requirements and solution times. A mesh metamorphosis tool is used to ensure finite element models match geometry obtained from a three-dimensional optical scanner. This tool also produces a common mesh pattern from sector-to-sector. This is exploited to produce common permutation matrices and symbolic factorizations of sector stiffness matrices that are proposed for reuse in solving subsequent constraint modes. Furthermore, a drop tolerance is introduced to remove small values during constraint mode calculation to reduce memory requirements. It is proposed to reuse this dropping pattern produced from a single sector on the remaining sectors. Approaches are then extended to a parallel processing scheme to propose effective matrix partitioning methods. Finally, information gathered during the constraint mode calculations is reused during the solution of the FINMs to improve solution time. Results show reusing permutation matrices and symbolic factorizations from sector-to-sector improves solution time and introduces no error. Using a drop tolerance is shown to reduce storage requirements of a constraint mode matrix, while reusing the dropping pattern introduces minimal error. Similarly, reusing constraint mode information in calculating normal modes greatly improves the performance.

Quantification of Cartilage Surface Degeneration by Curvature Analysis Using 3D Scanning in a Rabbit Model.

Accurate analysis to quantify cartilage morphology is critical for evaluating degenerative conditions in osteoarthritis (OA). Three-dimensional (3D) optical scanning provides 3D data for the entire cartilage surface; however, there is no consensus on how to quantify it. Our purpose was to validate a 3D method for evaluating spatiotemporal alterations in degenerative cartilages in a rabbit OA model by analyzing their curvatures at various stages of progression. Twelve rabbits underwent anterior cruciate ligament transection (ACLT) unilaterally and were divided into 4 groups: 4 weeks control, 4 weeks OA, 8 weeks control, and 8 weeks OA. 3D scanning, India ink staining, and histological assessments were performed in all groups. In 3D curvature visualization, the surfaces of the condyles were divided into 8 areas. The standard deviations (SD) of mean curvatures from all vertices of condylar surfaces and subareas were calculated. Regarding the site of OA change, curvature analysis was consistent with India ink scoring. The SD of mean curvature correlated strongly with the India ink Osteoarthritis Research Society International (OARSI) score. In curvature histograms, the curvature distribution in OA was more scattered than in control. Of the 8 areas, significant OA progression in the posterolateral part of the lateral condyle (L-PL) was observed at 4 weeks. The histology result was consistent with the 3D evaluation in terms of representative section. This study demonstrated that 3D scanning with curvature analysis can quantify the severity of cartilage degeneration objectively. Furthermore, the L-PL was found to be the initial area where OA degeneration occurred in the rabbit ACLT model.