Multi-level personalization of neuromusculoskeletal models to estimate physiologically plausible knee joint contact forces in children

Neuromusculoskeletal models are a powerful tool to investigate the internal biomechanics of an individual. However, commonly used neuromusculoskeletal models are generated via linear scaling of generic templates derived from elderly adult anatomies and poorly represent a child, let alone children with a neuromuscular disorder whose musculoskeletal structures and muscle activation patterns are profoundly altered. Model personalization can capture abnormalities and appropriately describe the underlying (altered) biomechanics of an individual. In this work, we explored the effect of six different levels of neuromusculoskeletal model personalization on estimates of muscle forces and knee joint contact forces to tease out the importance of model personalization for normal and abnormal musculoskeletal structures and muscle activation patterns. For six children, with and without cerebral palsy, generic scaled models were developed and progressively personalized by (1) tuning and calibrating musculotendon units' parameters, (2) implementing an electromyogram-assisted approach to synthesize muscle activations, and (3) replacing generic anatomies with image-based bony geometries, and physiologically and physically plausible muscle kinematics. Biomechanical simulations of gait were performed in the OpenSim and CEINMS software on ten overground walking trials per participant. A mixed-ANOVA test, with Bonferroni corrections, was conducted to compare all models' estimates. The model with the highest level of personalization produced the most physiologically plausible estimates. Model personalization is crucial to produce physiologically plausible estimates of internal biomechanical quantities. In particular, personalization of musculoskeletal anatomy and muscle activation patterns had the largest effect overall. Increased research efforts are needed to ease the creation of personalized neuromusculoskeletal models

Sale of tobacco products among minors in a satellite township near Kuala Lumpur, Malaysia. An observational study

Background Prevalence of smoking among minors is 18.2% in Malaysia. The legal age to buy tobacco products in Malaysia is 18 years and the Government intends to raise the permissible age to 21 years. The aim of the study was to assess the environment of the shops selling tobacco products about its sale among minors. The objective also included structured interviews of the sales personal regarding their knowledge and attitude towards the sale of tobacco products among minors. Methods Two researchers observed 31 shops/restaurants selling tobacco products (cigarettes/shisha). Shops within 500 meters of schools and universities were studied. Observations included presence of signages regarding ban on sales of tobacco products to minors and also the ban on sale of single sticks/loose cigarettes. Sales person of these shops willing to be interviewed were administered with a questionnaire and data was collected. Collected data was analysed using descriptive statistics. Results Out of 31 places, 5 were restaurants catering shisha and 26 were selling cigarettes. Two restaurants were catering shisha smoking to minors. Among the 26 shops selling cigarettes only 42.3% (n=11) had a clear signage regarding ban on sales of tobacco products to minors. Loose cigarettes were sold in 35 %( n=9) of the shops. Out of 26 shops, only 7 sales person were willing to be interviewed by the researcher (DDD). All interviewed individuals, were aware about the adverse health effects of smoking and the legal age to buy tobacco products in Malaysia. Five sales person agreed that they had sold tobacco products to minors. [Descriptive Statistics Showing Signages and sales] Conclusions Minors would be tempted to try tobacco products if strict ban is not enforced. Even though current laws exist to address the ban of tobacco products among minors, implementation seems to be weak in the studied locality. The authorities should monitor sale of tobacco products in future

An investigation into toothbrush wear related to months of use among university students

Background: Toothbrushes should be replaced every 3 to 4 months as older brushes lose their plaque removal ability. Older brushes may not be able to remove plaque from pits and fissures seen on the occlusal surfaces of the teeth or from the proximal areas between the teeth. The purpose of this study is to evaluate the wear seen on used toothbrushes (UTB) and the relation of wear with regards to the period of toothbrush use. Material and methods: UTB were collected from university students studying courses in arts and sciences faculties, excluding health sciences faculties, during an oral health awareness campaign conducted by the Faculty of Dentistry. A validated questionnaire was used to collect descriptive data regarding toothbrushing habits. Two calibrated examiners scored the UTB according to the Rawls et al. index. Authors also examined different types of toothbrushes and the cleanliness of the toothbrush handles. Results: The findings of the study show that 58.0% of the UTB were in good condition for optimal plaque removal (scores 0 and 1), whereas the remaining 42% were not in suitable condition for optimal plaque removal (scores 2 and 3). The UTB measured with Rawls et al.’s index were used for 2.7, 4.5, 5.9, and 7.0 months (mean number of months), respectively. Conclusion: Many factors, in addition to period of use, come into play with regards to the splaying of toothbrush bristles. Dental professionals should educate their clients about and reinforce the need to replace toothbrushes after 3 to 4 months of use or after significant wear of the bristles, whichever comes first

Prevalence of oral tori and exostosis in Malaysian population - a cross-sectional study

Oral tori and exostosis are non-pathological bony protuberances seen on the alveolar surfaces of the jaw bones. These are commonly seen on the palatal surfaces of the maxilla [torus palatinus (TP)] and around the premolars in the lingual surface of the mandible [torus mandibularis (TM)]. The aim of this cross-sectional study was to determine the prevalence of tori/exostosis in the Malaysian population.A total of 2666 patients were examined for the presence of tori and exostosis in the maxilla and mandible and were categorized into TP, TM, and exostosis (facial/labial). Collected data was analysed for obtaining descriptive statistics.882 subjects were noticed with oral tori/exostosis among the population studied with a prevalence rate of 33%. TP was seen more in females (35%), compared to males (20%), and this difference was statistically significant (p value\ua

Development and validation of statistical shape models of the primary functional bone segments of the foot

Introduction: Musculoskeletal models are important tools for studying movement patterns, tissue loading, and neuromechanics. Personalising bone anatomy within models improves analysis accuracy. Few studies have focused on personalising foot bone anatomy, potentially incorrectly estimating the foot's contribution to locomotion. Statistical shape models have been created for a subset of foot-ankle bones, but have not been validated. This study aimed to develop and validate statistical shape models of the functional segments in the foot: first metatarsal, midfoot (second-to-fifth metatarsals, cuneiforms, cuboid, and navicular), calcaneus, and talus; then, to assess reconstruction accuracy of these shape models using sparse anatomical data.Methods: Magnetic resonance images of 24 individuals feet (age = 28 +/- 6 years, 52% female, height = 1.73 +/- 0.8 m, mass = 66.6 +/- 13.8 kg) were manually segmented to generate three-dimensional point clouds. Point clouds were registered and analysed using principal component analysis. For each bone segment, a statistical shape model and principal components were created, describing population shape variation. Statistical shape models were validated by assessing reconstruction accuracy in a leave-one-out cross validation. Statistical shape models were created by excluding a participant's bone segment and used to reconstruct that same excluded bone using full segmentations and sparse anatomical data (i.e. three discrete points on each segment), for all combinations in the dataset. Tali were not reconstructed using sparse anatomical data due to a lack of externally accessible landmarks. Reconstruction accuracy was assessed using Jaccard index, root mean square error (mm), and Hausdorff distance (mm).Results: Reconstructions generated using full segmentations had mean Jaccard indices between 0.77 +/- 0.04 and 0.89 +/- 0.02, mean root mean square errors between 0.88 +/- 0.19 and 1.17 +/- 0.18 mm, and mean Hausdorff distances between 2.99 +/- 0.98 mm and 6.63 +/- 3.68 mm. Reconstructions generated using sparse anatomical data had mean Jaccard indices between 0.67 +/- 0.06 and 0.83 +/- 0.05, mean root mean square error between 1.21 +/- 0.54 mm and 1.66 +/- 0.41 mm, and mean Hausdorff distances between 3.21 +/- 0.94 mm and 7.19 +/- 3.54 mm. Jaccard index was higher (P < 0.01) and root mean square error was lower (P < 0.01) in reconstructions from full segmentations compared to sparse anatomical data. Hausdorff distance was lower (P < 0.01) for midfoot and calcaneus reconstructions using full segmentations compared to sparse anatomical data.Conclusion: For the first time, statistical shape models of the primary functional segments of the foot were developed and validated. Foot segments can be reconstructed with minimal error using full segmentations and sparse anatomical landmarks. In future, larger training datasets could increase statistical shape model robustness, extending use to paediatric or pathological populations

Development and validation of statistical shape models of the primary functional bone segments of the foot

Introduction: Musculoskeletal models are important tools for studying movement patterns, tissue loading, and neuromechanics. Personalising bone anatomy within models improves analysis accuracy. Few studies have focused on personalising foot bone anatomy, potentially incorrectly estimating the foot's contribution to locomotion. Statistical shape models have been created for a subset of foot-ankle bones, but have not been validated. This study aimed to develop and validate statistical shape models of the functional segments in the foot: first metatarsal, midfoot (second-to-fifth metatarsals, cuneiforms, cuboid, and navicular), calcaneus, and talus; then, to assess reconstruction accuracy of these shape models using sparse anatomical data. Methods: Magnetic resonance images of 24 individuals feet (age = 28 ± 6 years, 52% female, height = 1.73 ± 0.8 m, mass = 66.6 ± 13.8 kg) were manually segmented to generate three-dimensional point clouds. Point clouds were registered and analysed using principal component analysis. For each bone segment, a statistical shape model and principal components were created, describing population shape variation. Statistical shape models were validated by assessing reconstruction accuracy in a leave-one-out cross validation. Statistical shape models were created by excluding a participant's bone segment and used to reconstruct that same excluded bone using full segmentations and sparse anatomical data (i.e. three discrete points on each segment), for all combinations in the dataset. Tali were not reconstructed using sparse anatomical data due to a lack of externally accessible landmarks. Reconstruction accuracy was assessed using Jaccard index, root mean square error (mm), and Hausdorff distance (mm). Results: Reconstructions generated using full segmentations had mean Jaccard indices between 0.77 ± 0.04 and 0.89 ± 0.02, mean root mean square errors between 0.88 ± 0.19 and 1.17 ± 0.18 mm, and mean Hausdorff distances between 2.99 ± 0.98 mm and 6.63 ± 3.68 mm. Reconstructions generated using sparse anatomical data had mean Jaccard indices between 0.67 ± 0.06 and 0.83 ± 0.05, mean root mean square error between 1.21 ± 0.54 mm and 1.66 ± 0.41 mm, and mean Hausdorff distances between 3.21 ± 0.94 mm and 7.19 ± 3.54 mm. Jaccard index was higher (P < 0.01) and root mean square error was lower (P < 0.01) in reconstructions from full segmentations compared to sparse anatomical data. Hausdorff distance was lower (P < 0.01) for midfoot and calcaneus reconstructions using full segmentations compared to sparse anatomical data. Conclusion: For the first time, statistical shape models of the primary functional segments of the foot were developed and validated. Foot segments can be reconstructed with minimal error using full segmentations and sparse anatomical landmarks. In future, larger training datasets could increase statistical shape model robustness, extending use to paediatric or pathological populations.status: publishe

Magnetic resonance imaging and freehand 3-D ultrasound provide similar estimates of free achilles tendon shape and 3-D geometry

Obst, SJ ORCiD: 0000-0003-4299-9628The purpose of this study was to assess the similarity of free Achilles tendon shape and 3-D geometry between magnetic resonance imaging (MRI) and freehand 3-D ultrasound (3-DUS) imaging methods. Fourteen elite/sub-elite middle-distance runners participated in the study. MRI and 3-DUS scans of the Achilles tendon were acquired on two separate imaging sessions, and all 3-D reconstructions were performed using identical methods. Shape similarity of free Achilles tendon reconstructed from MRI and 3-DUS data was assessed using Jaccard index, Hausdorff distance and root mean square error (RMSE). The Jaccard index, Hausdorff distance and RMSE values were 0.76 ± 0.05, 2.70 ± 0.70 and 0.61 ± 0.10 mm, respectively. The level of agreement between MRI and 3-DUS for free Achilles tendon volume, length and average cross-sectional area (CSA) was assessed using Bland-Altman analysis. Compared to MRI, freehand 3-DUS overestimated volume, length and average CSA by 30.6 ± 15.8 mm3 (1.1% ± 0.6%), 0.3 ± 0.7 mm (0.6% ± 1.9%) and 0.3 ± 1.42 mm2 (0.4% ± 2.0%), respectively. The upper and lower limits of agreement between MRI and 3-DUS for volume, length and average CSA were −0.4 to 61.7 mm3 (−0.2% to 2.3%), −1.0 to 1.5 mm (−3.2% to 4.5%) and −2.5 to 3.1 mm2 (−3.5% to 4.3%), respectively. There were no significant differences between imaging methods in CSA along the length of the tendon. In conclusion, MRI and freehand 3-DUS may be considered equivalent methods for estimating shape and 3-D geometry of the free Achilles tendon. These findings, together with the practical benefits of being able to assess 3-D Achilles tendon shape and geometry in a laboratory environment and under isometric loading, make 3-DUS an attractive alternative to MRI for assessing 3-D free Achilles tendon macro-structure in future studies. © 2019 World Federation for Ultrasound in Medicine & Biolog

Radiographic assessment of apical root resorption in inflammatory periapical pathologies

Introduction: Apical root resorption (ARR) is a common condition associated with periapical pathologies which is invariably detected by intraoral periapical radiographs. Although it is common, its distribution in different periapical pathologies has not been assessed so far. The aim of this study was to determine the distribution and severity of ARR in common inflammatory periapical pathologies. Materials and Methods: A cross-sectional radiographic study was conducted on 333 patients who visited SEGi Oral Health Centre in the 6-month period of the study. Digital intraoral periapical radiographs of patients with clinically established periapical pathologies were taken. Data were collected using a structured proforma regarding the type of periapical lesions, presence or absence of ARR. Collected data were analyzed using SPSS version 21 and Chi-square test was applied to check the association between ARR and periapical pathologies. Results: During this study period, 333 patients with inflammatory periapical pathologies were reported. Of which 135 (40.5%) showed definite ARR. Among 135 ARR, 97 (71.9%) were moderate resorption and 38 (28.1%) were severe resorption. ARR was significantly greater in periapical granuloma and cyst (72.8%) followed by periapical abscess (35%) and acute apical periodontitis (18.1%) which was statistically significant (P < 0.001). Young adults (40.7%) and male patients (58.5%) had higher ARR compared to old-aged adults and female patients. Conclusion: The presence of ARR is the concern for the infection control in endodontics, as these conditions provide a favorable environment for bacterial colonization and also exact working length determination is difficult as there is altered apical constriction

Targeted achilles tendon training and rehabilitation using personalized and real-time multiscale models of the neuromusculoskeletal system

Obst, SJ ORCiD: 0000-0003-4299-9628Musculoskeletal tissues, including tendons, are sensitive to their mechanical environment, with both excessive and insufficient loading resulting in reduced tissue strength. Tendons appear to be particularly sensitive to mechanical strain magnitude, and there appears to be an optimal range of tendon strain that results in the greatest positive tendon adaptation. At present, there are no tools that allow localized tendon strain to be measured or estimated in training or a clinical environment. In this paper, we first review the current literature regarding Achilles tendon adaptation, providing an overview of the individual technologies that so far have been used in isolation to understand in vivo Achilles tendon mechanics, including 3D tendon imaging, motion capture, personalized neuromusculoskeletal rigid body models, and finite element models. We then describe how these technologies can be integrated in a novel framework to provide real-time feedback of localized Achilles tendon strain during dynamic motor tasks. In a proof of concept application, Achilles tendon localized strains were calculated in real-time for a single subject during walking, single leg hopping, and eccentric heel drop. Data was processed at 250 Hz and streamed on a smartphone for visualization. Achilles tendon peak localized strains ranged from 3 to 11% for walking, 5 to 15% during single leg hop, and 2 to 9% during single eccentric leg heel drop, overall showing large strain variation within the tendon. Our integrated framework connects, across size scales, knowledge from isolated tendons and whole-body biomechanics, and offers a new approach to Achilles tendon rehabilitation and training. A key feature is personalization of model components, such as tendon geometry, material properties, muscle geometry, muscle-tendon paths, moment arms, muscle activation, and movement patterns, all of which have the potential to affect tendon strain estimates. Model personalization is important because tendon strain can differ substantially between individuals performing the same exercise due to inter-individual differences in these model components