An investigation into the hammer toe effects on the lower extremity mechanics and plantar fascia tension: A case for a vicious cycle and progressive damage.

Hammer toes are one of the common deformities of the forefoot that can lead to compensatory changes during walking in individuals with this condition. Predicting the adverse effects of tissue damage on the performance of other limbs is very important in the prevention of progressive damage. Finite element (FE) and musculoskeletal modeling can be helpful by allowing such effects to be studied in a way where the internal stresses in the tissue could be investigated. Hence, this study aims to investigate the effects of the hammer toe deformity on the lower extremity, especially on the plantar fascia functions. To compare the joint reactions of the hammer toe foot (HTF) and healthy foot (HF), two musculoskeletal models (MSM) of the feet of a healthy individual and that of a participant with hammer toe foot were developed based on gait analysis. A previously validated 3D finite element model which was constructed using Magnetic Resonance Imaging (MRI) of the diabetic participant with the hammer toe deformity was processed at five different events during the stance phase of gait. It was found that the hammer toe deformity makes dorsiflexion of the toes and the windlass mechanism less effective during walking. Specifically, the FE analysis results showed that plantar fascia (PF) in HTF compared to HF played a less dominant role in load bearing with both medial and lateral parts of PF loaded. Also, the results indicated that the stored elastic energy in PF was less in HTF than the HF, which can indicate a higher metabolic cost during walking. Internal stress distribution shows that the majority of ground reaction forces are transmitted through the lateral metatarsals in hammer toe foot, and the probability of fifth metatarsal fracture and also progressive deformity was subsequently increased. The MSM results showed that the joint reaction forces and moments in the hammer toe foot have deviated from normal, where the metatarsophalangeal joint reactions in the hammer toe were less than the values in the healthy foot. This can indicate a vicious cycle of foot deformity, leading to changes in body weight force transmission line, and deviation of joint reactions and plantar fascia function from normal. These in turn lead to increased internal stress concentration, which in turn lead to further foot deformities. This vicious cycle cause progressive damage and can lead to an increase in the risk of ulceration in the diabetic foot.

An investigation of the ankle contact forces in a foot with hammer toe deformity. A comparison of patient-specific approaches using finite element modeling and musculoskeletal simulation.

The internal forces and stresses in the tissue are important as they are linked to the risk of mechanical trauma and injuries. Despite their value, the internal stresses and forces cannot be directly measured in-vivo. A previously validated 3D finite element model (FEM) was constructed using Magnetic Resonance Imaging (MRI) of a person with diabetes and hammer toe deformity. The foot model simulated at five different instances during the stance phase of gait. The internal stress distribution on the talus that was obtained using the FEM simulation, was used to calculate the joint reaction force at the ankle joint. In addition, the musculoskeletal model (MSM) of the participant with hammer toe foot was developed based on the gait analysis and was used to determine the muscle forces and joint reactions. The result showed that the vertical reaction forces obtained from the FEM and MSM follow a similar trend through the stance phase of gait cycle and are significantly correlated ( R=0.99). The joint reaction forces obtained through the two methods do not differ for the first 25% of the gait cycle, while the maximum difference was ∼0.7 Body weight that was observed at 50% of the stance phase. Clinical Relevance: Finite element modeling and musculoskeletal simulation can shed light on the internal forces at the ankle in pathological conditions such as hammer toe. The similarities and differences observed in the joint reaction forces calculated from the two methods can have implications in assessing the effect of clinical interventions.

A generic model for pandemics in networks of communities and the role of vaccination.

The slogan "nobody is safe until everybody is safe" is a dictum to raise awareness that in an interconnected world, pandemics, such as COVID-19, require a global approach. Motivated by the ongoing COVID-19 pandemic, we model here the spread of a virus in interconnected communities and explore different vaccination scenarios, assuming that the efficacy of the vaccination wanes over time. We start with susceptible populations and consider a susceptible-vaccinated-infected-recovered model with unvaccinated ("Bronze"), moderately vaccinated ("Silver"), and very-well-vaccinated ("Gold") communities, connected through different types of networks via a diffusive linear coupling for local spreading. We show that when considering interactions in "Bronze"-"Gold" and "Bronze"-"Silver" communities, the "Bronze" community is driving an increase in infections in the "Silver" and "Gold" communities. This shows a detrimental, unidirectional effect of non-vaccinated to vaccinated communities. Regarding the interactions between "Gold," "Silver," and "Bronze" communities in a network, we find that two factors play a central role: the coupling strength in the dynamics and network density. When considering the spread of a virus in Barabási-Albert networks, infections in "Silver" and "Gold" communities are lower than in "Bronze" communities. We find that the "Gold" communities are the best in keeping their infection levels low. However, a small number of "Bronze" communities are enough to give rise to an increase in infections in moderately and well-vaccinated communities. When studying the spread of a virus in dense Erdos-Rényi and sparse Watts-Strogatz and Barabási-Albert networks, the communities reach the disease-free state in the dense Erdos-Rényi networks, but not in the sparse Watts-Strogatz and Barabási-Albert networks. However, we also find that if all these networks are dense enough, all types of communities reach the disease-free state. We conclude that the presence of a few unvaccinated or partially vaccinated communities in a network can increase significantly the rate of infected population in other communities. This reveals the necessity of a global effort to facilitate access to vaccines for all communities.

Associations between changes in loading pattern, deformity, and internal stresses at the foot with hammer toe during walking; a finite element approach.

Over the past decade, Finite Element (FE) modelling has been used as a method to understand the internal stresses within the diabetic foot. Foot deformities such as hammer toe have been associated with increased risk of foot ulcers in diabetic patients. Hence the aim of this study is to investigate the influence of hammer toe deformity on internal stresses during walking. A 3D finite element model of the human foot was constructed based on capturing Magnetic Resonance Imaging (MRI) of a diabetic neuropathic volunteer exhibiting hammer toe. 3D gait measurements and a multi-body musculoskeletal model for the same participant were used to define muscle forces. FE simulations were run at five different instances during the stance phase of gait. Peak plantar pressure and pressure distribution results calculated from the model showed a good agreement with the experimental measurement having less than 11% errors. Maximum von Mises internal stresses in the forefoot hard tissue were observed at the 3rd and 5th metatarsals and 4th proximal phalanx. Moreover, presence of hammer toe deformity was found to shift the location of maximum internal stresses on the soft tissue to the forefoot by changing the location of centre of pressure with internal stress 1.64 times greater than plantar pressure. Hammer toe deformity also showed to reduce the involvement of the first phalanx in internal/external load-bearing during walking. The findings of this study support the association between changes in loading pattern, deformity, and internal stresses in the soft tissue that lead to foot ulceration.

Prognostic Role of Lymphovascular Invasion in Patients with Early Breast Cancer.

In this study, our aim was to evaluate the role of lymphovascular invasion (LVI) in the prognosis of patients with early stage breast cancer. The medical records of more than 7000 patients who suffered from invasive breast cancer and had undergone surgical treatment since December 1994 till December 2019, retrospectively. Patient's history, physical examination and the clinicopathological features, histopathology characteristics, immunohistochemical findings, adjuvant systemic therapy, recurrence rate, metastasis-free survival (MFS), disease-free survival (DFS), and overall survival (OS) were reviewed. A total of 5425 eligible patients were categorized into two groups based on the presence of LVI; 3031 (55.9%) patients had no LVI (group 1) and LVI was present in 2394 (44.1%) patients (group 2), then divided into LN-positive and -negative groups. Presence of LVI was significantly associated with patient age ≤ 40 years (p = 0.048), high histological grade (grades II and III, p < 0.001), tumor size between 2-5 cm and > 5 cm (p < 0.001), number of involved LN ≥ 4 (p < 0.001), and negative ER (p = 0.042) tumors. Five-year OS, MFS, and DFS were 93%, 88.9%, and 76.1% and 85.2%, 84.7%, and 73.6 in groups 1 and 2, respectively (P < 0.001). On multivariate analysis, LVI was an independent prognostic factor for DFS in all patients. Furthermore, histological grade II, histological grade III, and a higher number of involved LNs (≥ 4) were independent predictors in all patients. Thus, the presence of LVI can be considered as an independent prognostic factor for patients with operable breast cancer, irrespective of the LN status.

Three dimensional finite element modelling of metatarsal stresses during running.

Second metatarsal stress fractures are a problematic injury for runners and are formed when the rate of repair of bone is outpaced by the damage accumulated during loading. Measuring the peak stresses on the bone during running gives an indication of damage accumulation but direct measurement is invasive. Finite element modelling is a viable alternative method of accurately estimating bone stresses but tends to be too computationally expensive for use in applied research. This study presents a novel and simple finite element model which can estimate bone stresses on the second metatarsal during the stance phase of walking and running, accounting for joint reaction forces and soft tissue effects. The influence of the forces and kinematic inputs to the model and the presence of the soft tissues was quantified using a sensitivity analysis. The magnitudes of maximum stress from the model are similar to existing finite element models and bone staple strain gauge values collected during walking and running. The model was found to be most sensitive to the pitch angle of the metatarsal and the joint reaction forces and was less sensitive to the ground reaction forces under the metatarsal head, suggesting that direct measurement of external forces should not be assumed to represent internal stresses.

Paediatric burn injuries requiring hospitalization in Fars, Southern Iran.

The aim of this study was to determine the demographic characteristics of burnt children in need of hospitalization, causes of burns and associated complications in Fars province, Iran. This is a retrospective cross-sectional study. Files of all children under 15 years of age who were hospitalized in the only burn referral centre of Fars province were evaluated. Data regarding age, gender, location (urban, rural), burn surface area (BSA), cause of burn, length of hospital stay and complications were extracted from patients' files. Data were analyzed using SPSS, version 22 and the Chi-square test. A p-value of less than 0.05 was considered as statistically significant. A total of 122 patients (54.9% males) were studied. Children from rural areas were hospitalized 1.4 times more often than urban children. Overall, 31.2% of admissions occurred in winter. Burning with hot liquids (scalding) was the most common cause of burns (56.6%, n = 69). Mean BSA was 12.29 ± 21.18% and mean length of hospital stay was 7.59 ± 12.78 days. Burn complications were seen in 19 cases (15.6%). One child died due to inhalational thermal injury. This study showed that burns mostly occur in boys, in the winter and in rural areas of Fars province. Furthermore, scald burns are the most common type of burn injury. Since a significant number of children suffer from permanent complications following burn injuries, special planning is needed to prevent this type of injury.

Le but de cet étude rétrospective était de déterminer les caractéristiques démographiques, les causes et les complications des brûlures pédiatriques ayant nécessité une hospitalisation à Fars (Iran). Les dossiers des enfants (<15 ans) hospitalisés dans le CTB de Fars ont été évalués. Les données concernant l'âge, le sexe, l'habitat (rural ou urbain), la surface brûlée (SB), la cause, la durée de séjour et les complications ont été recueillies et analysées par X² au moyen de SPSS 22, avec un seuil de significativité à p≤ 0,05. Cent vingt deux dossiers (54,9% de garçons) ont été étudiés. Les rapports enfants ruraux/urbains était de 1,4/1. Il y avait un pic d'admissions en hiver (31,4%). Un ébouillantement était le mécanisme le plus fréquent (69 fois soit 56,6%). La surface brûlée moyenne était de 12,29 (+/- 21,18%), et la durée moyenne d'hospitalisation était de 7,59 +/- 12,78. Un enfant est mort, dans un contexte d'inhalation de fumées. Dix neuf séquelles (15,6%) ont été observées. Les brûlures (qui sont plus souvent des ébouillantements) touchent donc plutôt des garçons, ruraux, pendant l'hiver. Dans la mesure où un nombre significatif d'enfants brûlés gardent des séquelles, des actions de prévention spécifiques sont nécessaires.

Late development of pancreatitis following gunshot trauma, a case report.

BACKGROUND: Gunshot trauma to the pancreatic duct mainly have been published from wartime experiences, but bullet injury in these cases has lead to pancreatic duct disruption, not obstruction. We report a case of chronic pancreatitis which is presented 27 years following pancreatic duct obstruction due to bullet injury during wartime, which successfully treated. He was a 45-year-old man came with chronic epigastric abdominal pain. Physical examination was suggestive of pancreatitis and laboratory data confirmed the diagnosis. Imaging studies revealed a metallic object in main pancreatic duct. He carefully treated with pancreatic head resection and pancreaticojejunal anastomosis.

Antioxidant properties of peel and pulp hydro extract in ten Persian pomegranate cultivars.

This study compares the antioxidant activity of ten different pomegranate cultivars grown in Iran using the ferric reducing power assay (FRAP assay), which is based on the reduction of a ferric-tripyridyl triazine complex to its ferrous, colored form in the presence of antioxidants. Aqueous solutions of known Fe(+2) concentration, in the range of 100-1000 micromol L(-1) were used for calibration. The results showed that among pulp and peel fractions the sour alac and sweet white peel cultivars had more FRAP value respectively. The pomegranate peel extract had markedly higher antioxidant capacity than the pulp extract. The peel extract of sweet white peel cultivar appeared to have more potential as a health supplement rich in natural antioxidants compared to the pulp and peel extracts of other pomegranate cultivars.