Training and attitudes concerning cardiac rehabilitation in Portugal: A national survey of physician members of the Portuguese Society of Cardiology.

INTRODUCTION AND OBJECTIVES: Cardiac rehabilitation (CR) is a central component in the management of cardiovascular disease. While its potential benefits have been extensively explored and confirmed, its implementation is still suboptimal, due to various possible barriers. This study aimed to assess training and attitudes concerning CR among physicians in a Portuguese setting. METHODS: An online questionnaire structured in three parts (participant characteristics, training and attitudes concerning CR, and a brief general knowledge assessment) was developed and sent to members of the Portuguese Society of Cardiology. The study population encompassed physicians with a medical specialty or residents from the third year onward of a specialty program. RESULTS: A total of 97 individuals (57.7% male, 61.9% aged ≤50 years) presented valid answers. CR was available at the workplace of 54.6% of participants. Most of them considered that the time allocated to CR training during residency was inadequate, and thought that more time was needed for this purpose. Most had not dedicated (or intended to dedicate) time for CR training, with lack of time being the most frequently attributed reason. In terms of referral, a substantial proportion of subjects did not refer patients, with lack of CR centers and human resources being the most frequent reasons. CONCLUSIONS: This survey provides contemporary data on CR training and attitudes, highlighting areas of potential improvement, such as time allocated to training in this area. These results could provide a useful pragmatic framework for optimization of training and awareness in this pivotal field of cardiovascular medicine.

Progression of partial to complete ruptures of the Achilles tendon during rehabilitation: A study using a finite element model.

Substantial research on complete Achilles tendon ruptures is available, but guidance on partial ruptures is comparatively sparse. Conservative management is considered acceptable in partial tendon ruptures affecting less than 50% of the tendon's width, but supporting experimental evidence is currently lacking. Using a previously validated finite element model of the Achilles tendon, this study aimed to assess whether loading conditions simulating an early functional rehabilitation protocol could elicit progression to a complete rupture in partial ruptures of varying severity. In silico tendon rupture simulations were performed to locate the most likely rupture site for least, moderate, and extreme subtendon twist configurations. These three models were split at the corresponding rupture site and two sets of partial ruptures were created for each, starting from the medial and lateral sides, and ranging from 10% to 50% loss of continuity. Simulations were conducted with material parameters from healthy and tendinopathic tendons. Partial ruptures were considered to progress if the volume of elements showing a maximum principal strain above 10% exceeded 3 mm3 . To assess whether the tendinopathic tendons typical geometric characteristics could compensate for the inferior material properties found in tendinopathy, an additional model with increased cross-sectional area in the free tendon region was developed. Progression to complete ruptures occurred even with less than a 50% loss of continuity, regardless of subtendon twisting, and material parameters. The tendinopathic tendon model with increased cross-sectional area showed similar results. These findings suggest the current criteria for surgical treatment of partial ruptures should be reconsidered. Statement of clinical significance: The clinical significance and most appropriate treatment of partial ruptures of the Achilles tendon is unclear. Despite the widespread use of the "50% rule" in treatment decisions of partial tendon ruptures, experimental evidence supporting it is missing. The present study provides new data, from a validated aponeurotic and free Achilles tendon finite element model, showing that partial ruptures may progress to complete ruptures under loading conditions elicited from functional rehabilitation protocols, even for partial ruptures affecting less than 50% of the tendon's width. Under these novel findings, the current criteria for surgical treatment of partial ruptures should be reconsidered.

Atrioventricular block secondary to transient causes and long-term recurrence after an index event.

BACKGROUND: Atrioventricular block (AVB) secondary to transient causes can recover with its correction. However, studies assessing predictors of recovery and long-term recurrence are lacking. METHODS: Patients with advanced or complete AVB who had a reversible cause admitted in a single expert center were retrospectively studied. Patients with AVB secondary to acute coronary syndromes were excluded from analysis. RESULTS: In a population of 162 patients, the main factors associated with recovery of rhythm without a permanent pacemaker (PPM) implantation were the presence of chronic kidney disease (CKD) on dialysis (OR 7.6; CI 95% 1.2-47.5 (p = .03)); greater serum potassium levels (OR 2.3; CI 95% 1.28-4.0 (p < .01)), higher dosage of bradycardic drugs (OR 2.2; CI 95% 1.13-4.4 (p = .02)), the association between different bradycardic drugs (OR 9.0; CI 95% 2.02-40.3 (p < .01)) and between drug therapy and hyperkaliemia (OR 5.2; CI 95% 1.8-15.1 (p < .01)). There was an overall high burden of conductions abnormalities which did not correlate with recovery of rhythm (OR 0.5; CI 95% 0.19-1.5 (p = .23)). In 29 patients (17.9%) there was a correction of the AVB. During a maximum follow-up of 130 months, 24 patients (82.8%) had a recurrence which warranted a PPM. In the overall cohort only five patients (3%) had sustained recovery of rhythm. CONCLUSIONS: Recovery of AVB was mainly observed with higher doses of drug therapy, higher serum potassium levels or a combination of factors and regardless of baseline conduction abnormalities. The high rate of recurrence during follow-up warrants a close follow-up or PPM implantation at index admission.

A Three-Year Study on the Nutritional Composition and Occurrence of Mycotoxins of Corn Varieties with Different Transgenic Events Focusing on Poultry Nutrition.

Corn is one of the most produced cereals in the world and plays a major role in poultry nutrition. As there is limited scientific information regarding the impact of transgenic technology on the quality and nutrient composition of the grains, this study investigated the effect of three major transgenic corn varieties-VT PRO3®, PowerCore® ULTRA, and Agrisure® Viptera 3-on the field traits, nutrient composition, and mycotoxin contamination of corn grains cultivated in southern Brazil during three consecutive harvests. VT PRO3®, while demonstrating superior crop yield, showed susceptibility to mycotoxins, particularly fumonisins. In contrast, PowerCore® ULTRA, with the lowest yield, consistently exhibited lower levels of fumonisins. VT PRO3® had higher AMEn than the other varieties, while PowerCore® ULTRA had the highest total and digestible amino acid contents over the three years. The study's comprehensive analysis reveals the distinct impact of transgenic corn technologies on both productivity and nutritional levels. Balancing the crops yield, mycotoxin resistance, and nutritional content of corn is crucial to meet the demands of the poultry feed industry. Such insights are essential for decision-making, ensuring sustainability and efficiency in agricultural production as well as meeting the demands of the poultry industry.

The challenging approach of a young patient with a primary intimal sarcoma of the heart: a case report.

Background: Primary intimal sarcomas of the heart are extremely rare and have a dismal prognosis. Their management represents a complex clinical challenge since complete surgical resection is the only reliable possibility of cure but is only possible in 50% of patients. In non-resectable disease, anthracycline-based therapy is the most effective treatment, but pazopanib may be used in patients unfit to receive anthracyclines. Case summary: A 38-year-old man presented with acute right heart failure symptoms due to a primary intimal sarcoma of the heart. A definite diagnosis was made after cardiac surgery. Multi-modality cardiac imaging showed early recurrence of disease with mitral valve and pulmonary veins' invasion, and the patient was deemed inoperable. Due to chronic kidney disease and previous heart failure symptoms, he was started on first-line pazopanib palliative treatment. After 11 months of chemotherapy, there was good clinical tolerance and no evidence of disease progression, which occurred after 13 months. Discussion: This case highlights the value of a multi-modality imaging approach for cardiac masses. Most importantly, it reports the successful treatment of a young patient with a primary intimal sarcoma of the heart who was started on palliative pazopanib, with a significantly higher progression-free survival than is reported in the literature. This finding may support pazopanib as a good alternative as first-line treatment when there is contraindication for anthracycline-based chemotherapy.

Underuse of reperfusion therapy with systemic thrombolysis in high-risk acute pulmonary embolism in a Portuguese center.

INTRODUCTION: Reperfusion therapy is generally recommended in acute high-risk pulmonary embolism (HR-PE), but several population-based studies report that it is underused. Data on epidemiology, management and outcomes of HR-PE in Portugal are scarce. OBJECTIVE: To determine the reperfusion rate in HR-PE patients, the reasons for non-reperfusion, and how it influences outcomes. METHODS: In this retrospective cohort study of consecutive HR-PE patients admitted to a thromboembolic disease referral center between 2008 and 2018, independent predictors for non-reperfusion were assessed by multivariate logistic regression. PE-related mortality and long-term MACE (cardiovascular mortality, PE recurrence and chronic thromboembolic disease) were calculated according to the Kaplan-Meier method. Differences stratified by reperfusion were assessed using the log-rank test. RESULTS: Of 1955 acute PE patients, 3.8% presented with hemodynamic instability. The overall reperfusion rate was 50%: 35 patients underwent systemic thrombolysis, one received first-line percutaneous embolectomy and one rescue endovascular treatment. Independent predictors of non-reperfusion were: age, with >75 years representing 12 times the risk of non-treatment (OR 11.9, 95% CI 2.7-52.3, p=0.001); absolute contraindication for thrombolysis (31.1%), with recent major surgery and central nervous system disease as the most common reasons (OR 16.7, 95% CI 3.2-87.0, p<0.001); and being hospitalized (OR 7.7, 95% CI 1.4-42.9, p=0.020). At a mean follow-up of 2.5±3.3 years, the survival rate was 33.8%. Although not reaching statistical significance for hospital mortality, mortality in the reperfusion group was significantly lower at 30 days, 12 months and during follow-up (relative risk reduction of death of 64% at 12 months, p=0.013). Similar results were found for MACE. CONCLUSIONS: In this population, the recommended reperfusion therapy was performed in only 50% of patients, with advanced age and absolute contraindications to fibrinolysis being the main predictors of non-reperfusion. In this study, thrombolysis underuse was associated with a significant increase in short- and long-term mortality and events.

Stent for life initiative in Portugal: Progress through years and Covid-19 impact.

BACKGROUND: During Stent for Life Initiative in Portugal lifetime, positive changes in ST elevation myocardial infarction treatment were observed, by the increase of Primary Angioplasty numbers and improvements in patients' behaviour towards myocardial infarction, with an increase in those who called 112 and the lower proportion attending non primary percutaneous coronary intervention centres. Despite public awareness campaigns and system educational programmes, patient and system delay did not change significantly over this period. The aim of this study was to address the public awareness campaign effectiveness on peoples' behaviour facing STEMI, and how Covid-19 has affected STEMI treatment. METHODS: Data from 1381 STEMI patients were collected during a one-month period each year, from 2011 to 2016, and during one and a half month, matching first lockdown in Portugal 2020. Four groups were constituted: Group A (2011); Group B (2012&2013); Group C (2015&2016) and group D (2020). RESULTS: The proportion of patients who called 112, increased significantly (35.2% Group A; 38.7% Group B; 44.0% Group C and 49.6% Group D, p = 0.005); significant reduction was observed in the proportion of patients who attended healthcare centres without PPCI (54.5% group A; 47.6% Group B; 43.2% Group C and 40.9% Group D, p = 0.016), but there were no differences on groups comparison. Total ischemic time, measured from symptoms onset to reperfusion increased progressively from group A [250.0 (178.0-430.0)] to D [296.0 (201.0-457.5.8)] p = 0.012, with statistically significant difference between group C and D (p = 0.034). CONCLUSIONS: During the term of SFL initiative in Portugal, patients resorted less to primary health centres and called more to 112. These results can be attributed the public awareness campaign. Nevertheless, patient and system delays did not significantly change over this period, mainly in late years of SFL, probably for low efficacy of campaigns and in 2020 due to Covid-19 pandemic.

Return-to-performance in elite soccer players after Achilles tendon ruptures: a study using a weighted plus/minus metric and matched-control analysis.

PURPOSE: Studies have shown decreased match participation and shortened careers in athletes suffering Achilles tendon ruptures (ATRs), but assessment using a true performance metric is lacking. Plus/minus (PM) metrics provide a practical and objective approach to player performance assessment and are commonly used in other sports. This study aimed to quantify and compare individual player performance variations in elite football league players who sustained ATRs and returned to play within 1 year compared to those without ATRs, using a PM metric. METHODS: Player and team data were sourced from Transfermarkt.com. Male players sustaining ATRs between 2007 and 2018 were identified through injury reports. A control group (CTRL) was matched by position, age, height, and league, with a 6:1 ratio of controls to ATR subjects. The day of injury was considered "time zero". Year -1 corresponds to the 360 days preceding injury, and Year 1 to the interval between 360 and 720 days after. Performance in the player's main team was evaluated using a previously validated weighted PM metric. Only data from Year -1 and Year 1 were used for ATR versus CTRL group comparisons. Statistical significance was set at p < 0.05. RESULTS: The ATR group included 125 athletes. Data from more than 76,000 matches were analyzed. No statistically significant differences in net weighted PM metric between Year -1 and Year 1 were found. CONCLUSION: No differences were found between athletes suffering from ATRs and controls regarding the weighted PM metric. LEVEL OF EVIDENCE: III.

Prevalence and predictors of chronic thromboembolic pulmonary hypertension following severe forms of acute pulmonary embolism.

INTRODUCTION AND OBJECTIVES: The true prevalence of chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism (PE) in the Portuguese population remains unknown. We aimed to assess the prevalence and predictors of CTEPH two years after a symptomatic high- (HR) or intermediate-high risk (IHR) PE. METHODS: We conducted a retrospective cohort study of patients admitted with PE between 2014 and 2019 to a Portuguese referral center for pulmonary hypertension. RESULTS: In this single-center registry of 969 patients admitted with PE (annual incidence of 46/100000 population), 194 had HR (5.4%) and IHR (14.7%) PE. After excluding patients who died or had no follow-up in the first three months, 129 patients were included in the analysis. The overall prevalence of suspected CTEPH by clinical assessment, Doppler echocardiography and V/Q lung scan was 6.2% (eight patients). CTEPH was confirmed by right heart catheterization in four of these (3.1%). Increased pulmonary artery systolic pressure (PASP) at admission (OR 1.12; 95% CI 1.04-1.22; p=0.005) and the presence of varicose veins in the lower limbs (OR 7.47; 95% CI 1.53-36.41; p=0.013) were predictors of CTEPH. PASP >60 mmHg at admission identified patients with CTEPH at follow-up with sensitivity and specificity of 83.3% and 76.3%, respectively. All patients diagnosed with CTEPH had at least two radiological findings suggestive of CTEPH at the index event. CONCLUSIONS: In our cohort, the prevalence of CTEPH in survivors of severe forms of acute PE was 6.2%. PASP above 60 mmHg and supporting radiological findings on the index computed tomography scan are highly suggestive of acute-on-chronic CTEPH.

Injection of kaolin/carrageenan in the rat knee joint induces progressive experimental knee osteoarthritis.

ABSTRACT: Osteoarthritis (OA), the most common joint disorder worldwide, is characterized by progressive degeneration of articular and periarticular structures, leading to physical and emotional impairments that greatly affect the quality of life of patients. Unfortunately, no therapy has been able to halt the progression of the disease. Owing to the complexity of OA, most animal models are only able to mimic a specific stage or feature of the human disorder. In this work, we demonstrate the intraarticular injection of kaolin or carrageenan leads to the progressive degeneration of the rat's knee joint, accompanied by mechanical hyperalgesia and allodynia, gait impairments (reduced contact area of the affected limb), and radiological and histopathological findings concomitant with the development of human grade 4 OA. In addition, animals also display emotional impairments 4 weeks after induction, namely, anxious and depressive-like behaviour, important and common comorbidities of human OA patients. Overall, prolonging kaolin or carrageenan-induced monoarthritis mimics several important physical and psychological features of human OA in both male and female rodents and could be further applied in long-term studies of OA-associated chronic pain.

Practice of debriefing of critical events: a survey-based cross-sectional study of Portuguese anesthesiologists.

Debriefing is an essential procedure for identifying medical errors, improving communication, reviewing team performance, and providing emotional support after a critical event. This study aimed to describe the current practice and limitations of debriefing and gauge opinions on the best timing, effectiveness, need for training, use of established format, and expected goals of debriefing among Portuguese anesthesiologists. Methods: We performed a national cross-sectional online survey exploring the practice of anesthesiologists' debriefing practice after critical events in Portuguese hospitals. The questionnaire was distributed using a snowball sampling technique from July to September 2021. Data were descriptively and comparatively analyzed. Results: We had replies from 186 anesthesiologists (11.3% of the Portuguese pool). Acute respiratory event was the most reported type of critical event (96%). Debriefing occurred rarely or never in 53% of cases, 59% of respondents needed more training in debriefing, and only 4% reported having specific tools in their institutions to carry it out. There was no statistical association between having a debriefing protocol and the occurrence of critical events (P=.474) or having trained personnel (P=.95). The existence of protocols was associated with lower frequencies of debriefing (P=.017). Conclusions: Portuguese anesthesiologists know that debriefing is an essential process that increases patient safety, but among those surveyed, there is a need for an adequate debriefing culture or practice. Trial registration: Research registry 7741 (https://www.researchregistry.com/browse-the-registry#home).

Glossopharyngeal neuralgia with cardioinhibitory syncope: Is a permanent pacemaker required?

Glossopharyngeal neuralgia is a rare facial pain syndrome, which in more rare cases can be associated with syncope. We present the outcome of a case report that combines this rare association that received medical therapy with anti-epileptic medication and permanent dual chamber pacemaker implantation. In this case, syncope episodes were associated with both vasodepressor and cardioinhibitory reflex syncope types. The patient found relief from syncope, hypotension, and pain after initiation of anti-epileptic therapy. Although a dual chamber pacemaker was implanted, the pacemaker interrogation revealed no requirement for pacing at one-year follow-up. As far as we know, this is the first case that reports pacemaker interrogation during follow-up and, taking into account the absence of pacemaker activation at one-year follow-up, the device was not needed to prevent bradycardia and syncope episodes. This case report supports the current guidelines for pacing in neurocardiogenic syncope, by demonstrating a lack of requirement for pacing in the event of both cardioinhibitory and vasodepressor responses.

Blueprint for developing an effective pulmonary embolism response network.

INTRODUCTION: Acute pulmonary embolism (PE) is a major cause of morbidity and mortality in Portugal. It is the third most common cause of cardiovascular death after stroke and myocardial infarction. However, the management of acute PE remains poorly standardized, and there is a lack of access to mechanical reperfusion when indicated. METHODS AND RESULTS: This working group analyzed the current clinical guidelines for the use of percutaneous catheter-directed treatment in this setting and proposed a standardized approach for severe forms of acute PE. This document also proposes a methodology for the coordination of regional resources in order to create an effective PE response network, based on the hub-and-spoke organization design. CONCLUSION: This model can be applied at the regional level, but it is desirable to extend it to the national level.

Percutaneous versus surgical revascularization of unprotected left main coronary artery: Data from the Portuguese Registry of Acute Coronary Syndromes (ProACS).

BACKGROUND: In acute coronary syndromes (ACS), the optimal revascularization strategy for unprotected left main coronary artery (ULMCA) culprit lesion has been under-investigated. Therefore, we compared clinical characteristics and short- and medium-term outcomes of percutaneous and surgical revascularization in ACS. METHODS AND RESULTS: Of 31886 patients enrolled in a multicenter, national, prospective registry study between October 2010 and December 2020, 246 (0.8%) had ULMCA as a culprit lesion and underwent percutaneous coronary intervention (PCI) alone (n=133, 54%) or coronary artery bypass grafting (CABG) alone (n=113, 46%). Patients undergoing PCI presented more frequently ongoing chest pain (68% versus 41%, p<0.001) and cardiogenic shock (25% versus 1%, p<0.001). Time from admission to revascularization was higher in surgical group with a median time to CABG of 4.5 days compared to 0 days to PCI (p<0.001). Angiographic success rate was 93.2% in patients who underwent PCI. Primary endpoint (all-cause death, non-fatal reinfarction and/or non-fatal stroke during hospitalization) occurred in 15.9% of patients and was more frequent in the PCI group (p<0.001). After adjustment, surgical revascularization was associated with better in-hospital prognosis (odds ratio (OR) 0.164; 95% confidence interval (CI), 0.04-0.64; p=0.009). Similar results were achieved after propensity score matching. No difference was found at one-year all-cause death. CONCLUSION: Percutaneous coronary intervention was the most common revascularization strategy in the ACS with ULMCA culprit lesion. PCI was preferred in unstable patients and presented a high angiographic success. CABG was often delayed and preferred in low-risk patients. At one-year follow-up, PCI and CABG conferred a similar prognosis. The two approaches appear complementary in this high risk cohort.

Impact of Ketamine on Quality of Recovery after Laparoscopic Surgery: A Single-Centre Single-Blinded Trial Using the QoR-15 Questionnaire.

Background: The quality of recovery is a cluster of patient-related outcomes that emphasise not only pain but different physical and emotional dimensions. Traditionally, ketamine is used to improve postoperative analgesia and avoid opioid consumption and opioid-related side effects. Objective: The present study sought to evaluate if intraoperative ketamine administration (as a part of multimodal analgesia) influences the quality of recovery after laparoscopic surgery. Design: A prospective two-armed, single-blinded trial. Settings. Tertiary single-centre trial between July 2021 and January 2022. Patients. From the 146 patients initially admitted to the study, 127 patients were enrolled, 60 in the ketamine group (group K) and 67 in the control group (group NK). Intervention. Both groups received a rigid intraoperative anaesthesia protocol; furthermore, in group K, 0.5 mg/kg of the ideal body weight of ketamine was administered. Main Outcome Measures. The primary outcome was to evaluate the effect of ketamine administration on the postoperative quality of recovery using the Portuguese version of the Quality of Recovery-15 (QoR-15) Questionnaire 24 h after surgery. The total score and minimal clinically significant difference (MCID) of the QoR-15 were compared. Other variables were also assessed such as the presence of emergence delirium (ED), the Numeric Rating Scale (NRS) for pain, and the presence of postoperative nausea and vomiting (PONV). Results: A total of 127 patients were allocated to the study groups, 60 in group K and 67 in group NK. Regarding the primary outcome, no differences were found in individual categories (15 items) and in the total score of QoR-15 (p=0.214). Concerning improvement (MCID ≥ 8) or worsening (MCID ≤ 8) in quality of recovery, no difference was found between the groups (24 vs. 32 and 6 vs. 6; p=0.776). Finally, no difference was found in secondary postoperative outcomes including ED (p=0.55), NRS (p=0.401), and PONV (p=0.55). Conclusion: In this study, the administration of ketamine in laparoscopic surgery had no impact on the quality of recovery 24 h after surgery. This trial is registered with NCT03724019.

Dialogando com lacan para uma compreensão da estrutura das psicoses / A dialogue with lacan to understand the structure of psychoses

O trabalho realizado e que vai aqui apresentado consiste em uma apresentação do percurso empreendido por Jacques Lacan ([1955-56] 1988) no Seminário sobre As Psicoses. A proposta de chamar o nosso percurso de "diálogos" baseia-se na leitura de outros textos e notícias que reportam ao tema, ajudando-nos a melhor compreendê-lo. Não é um percurso simples e tampouco óbvio. A escrita de Lacan, ou mesmo a estrutura psicótica, abre continuamente outras portas pelas quais pode o observador perscrutar, embora não lhe seja permitido adentrar com suas ansiosas pretensões interpretativas, plenas de significantes simbólicos. Contente-se, pois, o clínico, com a função de secretário do delírio, compreendendo-o não simplesmente como uma defesa, mas como uma outra forma de se organizar diante de um outro ­ imagem de si e que rejeita habitar o complexo mundo da linguagem.

The work carried out and which will be presented here consists of a presentation of the journey undertaken by Jacques Lacan ([1955-56] 1988) at the Seminar on The Psychoses. The proposal to call our journey "dialogues" is based on reading other texts and news that report on the topic, helping us to better understand it. It is not a simple or obvious route. Lacan's writing, or even the psychotic structure, continually opens other doors through which the observer can peer, although he is not allowed to enter with his anxious interpretative pretensions, full of symbolic signifiers. Therefore, the clinician is content, with the role of secretary of the delusion, understanding it not simply as a defense, but as another way of organizing himself in front of another - an image of himself that rejects inhabiting the complex world of language.

Design and validation of a finite element model of the aponeurotic and free Achilles tendon.

The Achilles tendon (AT) is a common injury site. Ruptures are usually located in the free tendon but may cross the myotendinous junction into the aponeurotic region. Considering the possibility of aponeurotic region involvement in AT ruptures, a novel three dimensional (3D) finite element (FE) model that includes both the aponeurotic and free AT regions and features subtendon twisting and sliding was developed. It was hypothesized that the model would be able to predict in vivo data collected from the literature, thus being considered valid, and that model outputs would be most sensitive to subtendon twist configurations. The 3D model was constructed using magnetic resonance images. The model was divided into soleus and gastrocnemius subtendons. In addition to a frictionless contact condition, the interaction between subtendons was modeled using two contact formulations: sliding with anisotropic friction and no sliding. Loads were applied on the tendon's most proximal cross-section and anterior surface, with magnitudes estimated from in vivo studies. Model outputs were compared with experimental data regarding 3D deformation, transverse plane rotation, and nodal displacements in the free tendon. The FE model adequately simulated the free tendon behavior regarding longitudinal strain, cross-section area variation, transverse plane rotation, and sagittal nodal displacements, provided that subtendon sliding was allowed. The frictionless model exhibited noticeable medial transverse sliding of the soleus subtendon, which was present to a much lesser degree in the anisotropic friction model. Model outputs were most sensitive to variations in subtendon twist and dispersion of the collagen fiber orientations. Clinical Significance: This Achilles tendon finite element model, validated using in vivo experimental data, may be used to study its mechanical behavior, injury mechanisms, and rupture risk factors.