Physico-chemical characterization of the tumour microenvironment of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal malignancy that accounts for more than 90% of pancreatic cancer diagnoses. Our research is focused on the physico-chemical properties of the tumour microenvironment (TME), including its tumoural extracellular matrix (tECM), as they may have an important impact on the success of cancer therapies. PDAC xenografts and their decellularized tECM offer a great material source for research in terms of biomimicry with the original human tumour. Our aim was to evaluate and quantify the physico-chemical properties of the PDAC TME. Both cellularized (native TME) and decellularized (tECM) patient-derived PDAC xenografts were analyzed. A factorial design of experiments identified an optimal combination of factors for effective xenograft decellularization. Our results provide a complete advance in our understanding of the PDAC TME and its corresponding stroma, showing that it presents an interconnected porous architecture with very low permeability and small pores due to the contractility of the cellular components. This fact provides a potential therapeutic strategy based on the therapeutic agent size.

In silico assessment of the bone regeneration potential of complex porous scaffolds.

Mechanical environment plays a crucial role in regulating bone regeneration in bone defects. Assessing the mechanobiological behavior of patient-specific orthopedic scaffolds in-silico could help guide optimal scaffold designs, as well as intra- and post-operative strategies to enhance bone regeneration and improve implant longevity. Additively manufactured porous scaffolds, and specifically triply periodic minimal surfaces (TPMS), have shown promising structural properties to act as bone substitutes, yet their ability to induce mechanobiologially-driven bone regeneration has not been elucidated. The aim of this study is to i) explore the bone regeneration potential of TPMS scaffolds made of different stiffness biocompatible materials, to ii) analyze the influence of pre-seeding the scaffolds and increasing the post-operative resting period, and to iii) assess the influence of patient-specific parameters, such as age and mechanosensitivity, on outcomes. To perform this study, an in silico model of a goat tibia is used. The bone ingrowth within the scaffold pores was simulated with a mechano-driven model of bone regeneration. Results showed that the scaffold's architectural properties affect cellular diffusion and strain distribution, resulting in variations in the regenerated bone volume and distribution. The softer material improved the bone ingrowth. An initial resting period improved the bone ingrowth but not enough to reach the scaffold's core. However, this was achieved with the implantation of a pre-seeded scaffold. Physiological parameters like age and health of the patient also influence the bone regeneration outcome, though to a lesser extent than the scaffold design. This analysis demonstrates the importance of the scaffold's geometry and its material, and highlights the potential of using mechanobiological patient-specific models in the design process for bone substitutes.

The rise of mechanical metamaterials: Auxetic constructs for skin wound healing.

Auxetic materials are known for their unique ability to expand/contract in multiple directions when stretched/compressed. In other words, they exhibit a negative Poisson's ratio, which is usually positive for most of materials. This behavior appears in some biological tissues such as human skin, where it promotes wound healing by providing an enhanced mechanical support and facilitating cell migration. Skin tissue engineering has been a growing research topic in recent years, largely thanks to the rapid development of 3D printing techniques and technologies. The combination of computational studies with rapid manufacturing and tailored designs presents a huge potential for the future of personalized medicine. Overall, this review article provides a comprehensive overview of the current state of research on auxetic constructs for skin healing applications, highlighting the potential of auxetics as a promising treatment option for skin wounds. The article also identifies gaps in the current knowledge and suggests areas for future research. In particular, we discuss the designs, materials, manufacturing techniques, and also the computational and experimental studies on this topic.

Collagen-Laponite Nanoclay Hydrogels for Tumor Spheroid Growth.

The extracellular matrix (ECM) plays an important regulatory role in the development and progression of tumoral tissue. Its functions and properties are crucial in determining tumor cell behavior such as invasion, migration, and malignancy development. Our study explores the role of collagen type I in cancer development and spread using engineered tumor models like multicellular spheroids grown in collagen-based hydrogels to simulate early tumor formation. We employ microfluidic techniques to test the hypothesis that (i) adding Laponite nanoclay to collagen hydrogels modifies mechanical and rheological properties and (ii) changing the stiffness of the collagen microenvironment affects tumor spheroid growth. Our findings support our theories and suggest the use of ECM components and engineered tumor models in cancer research, offering a biocompatible and biomimetic method to tailor the mechanical properties of conventional collagen hydrogels.

Lifting COVID-19 mitigation measures in Spain (May-June 2020).

Introduction: The state of alarm was declared in Spain due to the COVID-19 epidemic on March 14, 2020, and established population confinement measures. The objective is to describe the process of lifting these mitigation measures. Methods: The Plan for the Transition to a New Normality, approved on April 28, contained four sequential phases with progressive increase in socio-economic activities and population mobility. In parallel, a new strategy for early diagnosis, surveillance and control was implemented. A bilateral decision mechanism was established between the Spanish Government and the autonomous communities (AC), guided by a set of qualitative and quantitative indicators capturing the epidemiological situation and core capacities. The territorial units were established ad-hoc and could be from Basic Health Zones to entire AC. Results: The process run from May 4 to June 21, 2020. AC implemented plans for reinforcement of core capacities. Incidence decreased from a median (50% of territories) of 7.4 per 100,000 in 7 days at the beginning to 2.5 at the end. Median PCR testing increased from 53% to 89% of suspected cases and PCR total capacity from 4.5 to 9.8 per 1000 inhabitants weekly; positivity rate decreased from 3.5% to 1.8%. Median proportion of cases with traced contacts increased from 82% to 100%. Conclusion: Systematic data collection, analysis, and interterritorial dialogue allowed adequate process control. The epidemiological situation improved but, mostly, the process entailed a great reinforcement of core response capacities nation-wide, under common criteria. Maintaining and further reinforcing capacities remained crucial for responding to future waves.

Introducción: El 14 de marzo de 2020 España declaró el estado de alarma por la pandemia por COVID-19 incluyendo medidas de confinamiento. El objetivo es describir el proceso de desescalada de estas medidas. Métodos: Un plan de transición hacia una nueva normalidad, del 28 de abril, incluía 4 fases secuenciales incrementando progresivamente las actividades socioeconómicas y la movilidad. Concomitantemente, se implementó una nueva estrategia de diagnóstico precoz, vigilancia y control. Se estableció un mecanismo de decisión bilateral entre Gobierno central y comunidades autónomas (CCAA), guiado por un panel de indicadores cualitativos y cuantitativos de la situación epidemiológica y las capacidades básicas. Las unidades territoriales evaluadas comprendían desde zonas básicas de salud hasta CCAA. Resultados: El proceso se extendió del 4 de mayo al 21 de junio y se asoció a planes de refuerzo de las capacidades en las CCAA. La incidencia disminuyó de una mediana inicial de 7,4 por 100.000 en 7 días a 2,5 al final del proceso. La mediana de pruebas PCR aumentó del 53% al 89% de los casos sospechosos, y la capacidad total de 4,5 a 9,8 pruebas semanales por 1.000 habitantes; la positividad disminuyó del 3,5% al 1,8%. La mediana de casos con contactos trazados aumentó del 82% al 100%. Conclusión: La recogida y análisis sistemático de información y el diálogo interterritorial logaron un adecuado control del proceso. La situación epidemiológica mejoró, pero sobre todo, se aumentaron las capacidades, en todo el país y con criterios comunes, cuyo mantenimiento y refuerzo fue clave en olas sucesivas.

Lifting COVID-19 mitigation measures in Spain (May-June 2020).

INTRODUCTION: The state of alarm was declared in Spain due to the COVID-19 epidemic on March 14, 2020, and established population confinement measures. The objective is to describe the process of lifting these mitigation measures. METHODS: The Plan for the Transition to a New Normality, approved on April 28, contained four sequential phases with progressive increase in socio-economic activities and population mobility. In parallel, a new strategy for early diagnosis, surveillance and control was implemented. A bilateral decision mechanism was established between the Spanish Government and the autonomous communities (AC), guided by a set of qualitative and quantitative indicators capturing the epidemiological situation and core capacities. The territorial units were established ad-hoc and could be from Basic Health Zones to entire AC. RESULTS: The process run from May 4 to June 21, 2020. AC implemented plans for reinforcement of core capacities. Incidence decreased from a median (50% of territories) of 7.4 per 100,000 in 7 days at the beginning to 2.5 at the end. Median PCR testing increased from 53% to 89% of suspected cases and PCR total capacity from 4.5 to 9.8 per 1000 inhabitants weekly; positivity rate decreased from 3.5% to 1.8%. Median proportion of cases with traced contacts increased from 82% to 100%. CONCLUSION: Systematic data collection, analysis, and interterritorial dialogue allowed adequate process control. The epidemiological situation improved but, mostly, the process entailed a great reinforcement of core response capacities nation-wide, under common criteria. Maintaining and further reinforcing capacities remained crucial for responding to future waves.

A bone-on-a-chip collagen hydrogel-based model using pre-differentiated adipose-derived stem cells for personalized bone tissue engineering.

Mesenchymal stem cells have contributed to the continuous progress of tissue engineering and regenerative medicine. Adipose-derived stem cells (ADSC) possess many advantages compared to other origins including easy tissue harvesting, self-renewal potential, and fast population doubling time. As multipotent cells, they can differentiate into osteoblastic cell linages. In vitro bone models are needed to carry out an initial safety assessment in the study of novel bone regeneration therapies. We hypothesized that 3D bone-on-a-chip models containing ADSC could closely recreate the physiological bone microenvironment and promote differentiation. They represent an intermedium step between traditional 2D-in vitro and in vivo experiments facilitating the screening of therapeutic molecules while saving resources. Herein, we have differentiated ADSC for 7 and 14 days and used them to fabricate in vitro bone models by embedding the pre-differentiated cells in a 3D collagen matrix placed in a microfluidic chip. Osteogenic markers such as alkaline phosphatase activity, calcium mineralization, changes on cell morphology, and expression of specific proteins (bone sialoprotein 2, dentin matrix acidic phosphoprotein-1, and osteocalcin) were evaluated to determine cell differentiation potential and evolution. This is the first miniaturized 3D-in vitro bone model created from pre-differentiated ADSC embedded in a hydrogel collagen matrix which could be used for personalized bone tissue engineering.

Flare-Ups in Crohn's Disease: Influence of Stress and the External Locus of Control.

(1) Background: The aim of this study was to explore the role of perceived stress and the health locus of control in Crohn's disease and their influence upon the development of flare-ups of this disease. (2) Methods: Stress and the external locus of control were evaluated in a sample of 64 Crohn's patients (flare-up phase versus latency phase). The perceived stress scale (PSS-14) and the multidimensional health locus of control scale were the measurement instruments used. (3) Results: The results indicate that the patients have high stress levels during a flare-up (26.13; 27.44; 28.79; 29.67); high stress levels (28.07; 29.67; 27.44; 28.07) if they have a high external locus of control; and that the external locus of control and stress levels have a significant influence upon the existence of flare-ups in those patients with low external locus of control levels (χ2 = 11.127; df = 1: p < 0.001). (4) Conclusions: Actions aimed at reducing stress and external locus of control levels are necessary in Crohn's disease.

Nurse Intervention: Attitudes and Knowledge About Organ Donation and Transplantation in Adolescents.

BACKGROUND: The problems involved in obtaining authorization in favor of organ donation have led us to evaluate the level of knowledge and attitudes of a group of Spanish adolescents (14-16 years) regarding organ donation, transplantation, and brain death. The evaluation was carried out before and after a health education intervention by nursing personnel. METHODS: Experimental, prospective and quantitative study. The educational intervention was carried out at Las Salinas high school (Laguna de Duero, Spain). We collected 86 preworkshop questionnaires and 88 post-workshop questionnaires. RESULTS: The composition of the groups did not differ significantly in sex (P = .653), age (P = .266), or in the desire to be a donor (P = .099). We found significant postworkshop improvements in knowledge about brain death (P < .001) and which organs can be donated (P < .001), as well as in the total score (18.29 ± 2.45 before vs 21.47 ± 2.70 after) (P < .001). We discovered a vast lack of knowledge about the organs that cannot be transplanted, which included the penis (38.4%), uterus (31.4%), prostate (41.9%), or bladder (37.2%); these beliefs decreased significantly after the intervention (P < .01). The increase in knowledge of the organs that can be donated, including eye (P = .024), lung (P = .025), stomach (P < .001), intestine (P = .001), and skin (P < .001), was also significant. CONCLUSIONS: The good results reflected the importance of conducting educational programs taught by health personnel on donation and organ transplantation in adolescents.

What Do We Know Today about Long COVID? Nursing Care for a New Clinical Syndrome.

Persistent COVID, long COVID, long-effects, long-term effects or chronic COVID are all names of a new syndrome caused by a set of multi-organ symptoms that appear after having been infected with SARS-CoV-2 [...].

Monkeypox outbreak predominantly affecting men who have sex with men, Madrid, Spain, 26 April to 16 June 2022.

Up to 22 June 2022, 508 confirmed cases of monkeypox (MPX) have been reported in the Madrid region of Spain, 99% are men (n = 503) with a median age of 35 years (range: 18-67). In this ongoing outbreak, 427 cases (84.1%) reported condomless sex or sex with multiple partners within the 21 days before onset of symptoms, who were predominantly men who have sex with men (MSM) (n = 397; 93%). Both the location of the rash, mainly in the anogenital and perineal area, as well as the presence of inguinal lymphadenopathy suggest that close physical contact during sexual activity played a key role in transmission. Several cases reported being at a sauna in the city of Madrid (n = 34) or a mass event held on the Spanish island of Gran Canaria (n = 27), activities which may represent a conducive environment for MPX virus spread, with many private parties also playing an important role. Because of the rapid implementation of MPX surveillance in Madrid, one of the largest outbreaks reported outside Africa was identified. To minimise transmission, we continue to actively work with LGBTIQ+ groups and associations, with the aim of raising awareness among people at risk and encouraging them to adopt preventive measures.

Decellularization of tumours: A new frontier in tissue engineering.

Cancer is one of the leading causes of death worldwide. The tumour extracellular matrix (ECM) has unique features in terms of composition and mechanical properties, resulting in a structurally and chemically different ECM to that of native, healthy tissues. This paper reviews to date the efforts into decellularization of tumours, which in the authors' view represents a new frontier in the ever evolving field of tumour tissue engineering. An overview of the ECM and its importance in cancer is given, ending with examples of research using decellularized tumours, which has already indicated potential therapeutic targets, unravelled malignancy mechanisms or response to chemotherapy agents. The review highlights that more research is needed in this area, which can answer important questions related to tumour formation and progression to ultimately identify new and effective therapeutic targets. Within the near-future of personalized medicine, this research can create patient-specific tumour models and therapeutic regimes.

In Vitro Hydrolytic Degradation of Polyester-Based Scaffolds under Static and Dynamic Conditions in a Customized Perfusion Bioreactor.

Creating biofunctional artificial scaffolds could potentially meet the demand of patients suffering from bone defects without having to rely on donors or autologous transplantation. Three-dimensional (3D) printing has emerged as a promising tool to fabricate, by computer design, biodegradable polymeric scaffolds with high precision and accuracy, using patient-specific anatomical data. Achieving controlled degradation profiles of 3D printed polymeric scaffolds is an essential feature to consider to match them with the tissue regeneration rate. Thus, achieving a thorough characterization of the biomaterial degradation kinetics in physiological conditions is needed. Here, 50:50 blends made of poly(ε-caprolactone)-Poly(D,L-lactic-co-glycolic acid (PCL-PLGA) were used to fabricate cylindrical scaffolds by 3D printing (⌀ 7 × 2 mm). Their hydrolytic degradation under static and dynamic conditions was characterized and quantified. For this purpose, we designed and in-house fabricated a customized bioreactor. Several techniques were used to characterize the degradation of the parent polymers: X-ray Photoelectron Spectroscopy (XPS), Gel Permeation Chromatography (GPC), Scanning Electron Microscopy (SEM), evaluation of the mechanical properties, weigh loss measurements as well as the monitoring of the degradation media pH. Our results showed that flow perfusion is critical in the degradation process of PCL-PLGA based scaffolds implying an accelerated hydrolysis compared to the ones studied under static conditions, and up to 4 weeks are needed to observe significant degradation in polyester scaffolds of this size and chemical composition. Our degradation study and characterization methodology are relevant for an accurate design and to tailor the physicochemical properties of polyester-based scaffolds for bone tissue engineering.

Clinical and Laboratory Features in Anti-NF155 Autoimmune Nodopathy.

BACKGROUND AND OBJECTIVES: To study the clinical and laboratory features of antineurofascin-155 (NF155)-positive autoimmune nodopathy (AN). METHODS: Patients with anti-NF155 antibodies detected on routine immunologic testing were included. Clinical characteristics, treatment response, and functional scales (modified Rankin Scale [mRS] and Inflammatory Rasch-built Overall Disability Scale [I-RODS]) were retrospectively collected at baseline and at the follow-up. Autoantibody and neurofilament light (NfL) chain levels were analyzed at baseline and at the follow-up. RESULTS: Forty NF155+ patients with AN were included. Mean age at onset was 42.4 years. Patients presented with a progressive (75%), sensory motor (87.5%), and symmetric distal-predominant weakness in upper (97.2%) and lower extremities (94.5%), with tremor and ataxia (75%). Patients received a median of 3 (2-4) different treatments in 46 months of median follow-up. Response to IV immunoglobulin (86.8%) or steroids (72.2%) was poor in most patients, whereas 77.3% responded to rituximab. HLA-DRB1*15 was detected in 91.3% of patients. IgG4 anti-NF155 antibodies were predominant in all patients; anti-NF155 titers correlated with mRS within the same patient (r = 0.41, p = 0.004). Serum NfL (sNfL) levels were higher in anti-NF155+ AN than in healthy controls (36.47 vs 7.56 pg/mL, p < 0.001) and correlated with anti-NF155 titers (r = 0.43, p = 0.001), with I-RODS at baseline (r = -0.88, p < 0.001) and with maximum I-RODS achieved (r = -0.58, p = 0.01). Anti-NF155 titers and sNfL levels decreased in all rituximab-treated patients. DISCUSSION: Anti-NF155 AN presents a distinct clinical profile and good response to rituximab. Autoantibody titers and sNfL are useful to monitor disease status in these patients. The use of untagged-NF155 plasmids minimizes the detection of false anti-NF155+ cases. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that anti-NF155 antibodies associate with a specific phenotype and response to rituximab.

Lifting COVID-19 mitigation measures in Spain (May-June 2020).

INTRODUCTION: The state of alarm was declared in Spain due to the COVID-19 epidemic on March 14, 2020, and established population confinement measures. The objective is to describe the process of lifting these mitigation measures. METHODS: The Plan for the Transition to a New Normality, approved on April 28, contained four sequential phases with progressive increase in socio-economic activities and population mobility. In parallel, a new strategy for early diagnosis, surveillance and control was implemented. A bilateral decision mechanism was established between the Spanish Government and the autonomous communities (AC), guided by a set of qualitative and quantitative indicators capturing the epidemiological situation and core capacities. The territorial units were established ad-hoc and could be from Basic Health Zones to entire AC. RESULTS: The process run from May 4 to June 21, 2020. AC implemented plans for reinforcement of core capacities. Incidence decreased from a median (50% of territories) of 7.4 per 100,000 in 7 days at the beginning to 2.5 at the end. Median PCR testing increased from 53% to 89% of suspected cases and PCR total capacity from 4.5 to 9.8 per 1000 inhabitants weekly; positivity rate decreased from 3.5% to 1.8%. Median proportion of cases with traced contacts increased from 82% to 100%. CONCLUSION: Systematic data collection, analysis, and interterritorial dialogue allowed adequate process control. The epidemiological situation improved but, mostly, the process entailed a great reinforcement of core response capacities nation-wide, under common criteria. Maintaining and further reinforcing capacities remained crucial for responding to future waves.

Multiscale modeling of bone tissue mechanobiology.

Mechanical environment has a crucial role in our organism at the different levels, ranging from cells to tissues and our own organs. This regulatory role is especially relevant for bones, given their importance as load-transmitting elements that allow the movement of our body as well as the protection of vital organs from load impacts. Therefore bone, as living tissue, is continuously adapting its properties, shape and repairing itself, being the mechanical loads one of the main regulatory stimuli that modulate this adaptive behavior. Here we review some key results of bone mechanobiology from computational models, describing the effect that changes associated to the mechanical environment induce in bone response, implant design and scaffold-driven bone regeneration.

Bacteriemia por Leuconostoc spp: Descripción de un caso / A case of bacteremia caused by Leuconostoc spp

Leuconostoc spp es una bacteria tipo coco gram-positivo; recientemente se ha demostrado su potencial patógeno, sobre todo en pacientes inmunodeprimidos y con factores de riesgo como la patología oncológica. Dentro de los cuadros clínicos que pueden producir destacan: neumonía, meningitis, endocarditis o bacteriemia, siendo estas últimas las más frecuentes. Cabe destacar su resistencia intrínseca al tratamiento con vancomicina, siendo el tratamiento de elección en estos casos la penicilina y otros fármacos pertenecientes al grupo de los beta-lactámicos. (AU)

Leuconostoc spp is a gram-positive bacterium which pathogenic potential has been recently demonstrated, especially in immunocompromised patients and in those with risk factors la oncologic diseases. It can cause infections presented as pneumonia, meningitis, endocarditis or bacteremia, being the last two the most frequent ones. It can be highlighted its intrinsic resistance to vancomycin, which makes penicillin and other beta-lactam antibiotics the first treatment options. (AU)

A new de novo SYT2 mutation presenting as distal weakness. Neuropathy or neuromuscular junction dysfunction?

We report the case of a patient with a clinical phenotype characterized by distal lower limb weakness and pes cavus. The electrophysiological study showed slightly reduced or normal amplitude of motor potentials, a decremental response to repetitive nerve stimulation and post-exercise facilitation. Muscle biopsy showed only mild neurogenic features. Genetic analysis included a clinical exome sequencing, followed by Sanger analysis. Three-dimensional (3D) models were generated with a SwissModel (https://swissmodel.expasy.org/) to explain the clinical observations and reinforce the pathogenic nature of the genetic variant identified. Genetic analysis demonstrated a new de novo heterozygous in frame deletion of the SYT2 gene (NM_177402.4: c.1082_1096del), confirmed by Sanger sequencing, which removes five aminoacids in the C2B domain of synaptotagmin-2 protein, that cause a profound effect on the structure and function of this synaptic vesicle protein. We identified a de novo genetic variant in the SYT2 gene, further supporting its association with a highly stereotyped clinical and electrophysiological phenotype. Our case showed electrophysiological features consistent with a presynaptic dysfunction in the neuromuscular junction with normal post-exercise amplitudes, not supporting the presence of predominant axonal damage. Although the analysis of SYT2 gene should be included in genetic analysis of patients presenting with this clinical phenotype that mimics motor neuropathy, clinicians have to consider the study of neuromuscular transmission to early identify this potentially treatable condition.

Mechano-driven regeneration predicts response variations in large animal model based on scaffold implantation site and individual mechano-sensitivity.

It is well founded that the mechanical environment may regulate bone regeneration in orthopedic applications. The purpose of this study is to investigate the mechanical contributions of the scaffold and the host to bone regeneration, in terms of subject specificity, implantation site and sensitivity to the mechanical environment. Using a computational approach to model mechano-driven regeneration, bone ingrowth in porous titanium scaffolds was simulated in the distal femur and proximal tibia of three goats and compared to experimental results. The results showed that bone ingrowth shifted from a homogeneous distribution pattern, when scaffolds were in contact with trabecular bone (max local ingrowth 12.47%), to a localized bone ingrowth when scaffolds were implanted in a diaphyseal location (max local ingrowth 20.64%). The bone formation dynamics revealed an apposition rate of 0.37±0.28%/day in the first three weeks after implantation, followed by limited increase in bone ingrowth until the end of the experiment (12 weeks). According to in vivo data, we identified one animal whose sensitivity to mechanical stimulation was higher than the other two. Moreover, we found that the stimulus initiating bone formation was consistently higher in the femur than in the tibia for all the individuals. Overall, the dependence of the osteogenic response on the host biomechanics means that, from a mechanical perspective, the regenerative potential depends on both the scaffold and the host environment. Therefore, this work provides insights on how the mechanical conditions of both the recipient and the scaffold contribute to meet patient and location-specific characteristics.

Automated muscle elongation measurement during reverse shoulder arthroplasty planning.

BACKGROUND: Adequate deltoid and rotator cuff elongation in reverse shoulder arthroplasty is crucial to maximize postoperative functional outcomes and to avoid complications. Measurements of deltoid and rotator cuff elongation during preoperative planning can support surgeons in selecting a suitable implant design and position. Therefore, this study presented and evaluated a fully automated method for measuring deltoid and rotator cuff elongation. METHODS: Complete scapular and humeral models were extracted from computed tomography scans of 40 subjects. First, a statistical shape model of the complete humerus was created and evaluated to identify the muscle attachment points. Next, a muscle wrapping algorithm was developed to identify the muscle paths and to compute muscle lengths and elongations after reverse shoulder arthroplasty implantation. The accuracy of the muscle attachment points and the muscle elongation measurements was evaluated for the 40 subjects by use of both complete and artificially created partial humeral models. Additionally, the muscle elongation measurements were evaluated for a set of 50 arthritic shoulder joints. Finally, a sensitivity analysis was performed to evaluate the impact of implant positioning on deltoid and rotator cuff elongation. RESULTS: For the complete humeral models, all muscle attachment points were identified with a median error < 3.5 mm. For the partial humeral models, the errors on the deltoid attachment point largely increased. Furthermore, all muscle elongation measurements showed an error < 1 mm for 75% of the subjects for both the complete and partial humeral models. For the arthritic shoulder joints, the errors on the muscle elongation measurements were <2 mm for 75% of the subjects. Finally, the sensitivity analysis showed that muscle elongations were affected by implant positioning. DISCUSSION: This study presents an automated method for accurately measuring muscle elongations during preoperative planning of shoulder arthroplasty. The results show that the accuracy in measuring muscle elongations is higher than the accuracy in indicating the muscle attachment points. Hence, muscle elongation measurements are insensitive to the observed errors on the muscle attachment points. Related to this finding, muscle elongations can be accurately measured for both a complete humeral model and a partial humeral model. Because the presented method also showed accurate results for arthritic shoulder joints, it can be used during preoperative shoulder arthroplasty planning, in which typically only the proximal humerus is present in the scan and in which bone arthropathy can be present. As the muscle elongations are sensitive to implant positioning, surgeons can use the muscle elongation measurements to refine their surgical plan.