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1.
Materials (Basel) ; 17(10)2024 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-38793308

RESUMEN

Giga-casting, a revolutionary approach for manufacturing large, single-piece car body components from aluminium, has emerged as a potential game-changer in the automotive industry. However, these large, thin-walled castings are prone to distortions during solidification and heat treatment processes. Straightening these distortions is crucial to ensure structural integrity, facilitate downstream assembly, and maintain aesthetic qualities. This paper proposes a novel method for straightening giga-cast components using a multi-pin straightening machine. The machine's versatility stems from its ability to adapt to various geometries through multiple strategically controlled straightening pins. This paper introduces the concept of a "straightening stroke decision algorithm" to achieve precise straightening and overcome the challenges of complex shapes. This algorithm determines the stroke length for each pin, combining a polynomial model representing the global stiffness of the component with a machine learning model that captures the stiffness changes arising from the current geometry. The effectiveness of the proposed approach is evaluated through comprehensive numerical experiments using finite element analyses. The straightening performance is assessed for the straightening algorithm with different machine learning models (deep neural network and XGBoost) and compared to a traditional optimisation method. The proposed surrogate models decided the straightening strokes so that the maximum remaining distortion became 0.02% of the largest dimension of each target geometry. The results of the numerical experiment showed that the proposed straightening method is suitable for straightening distortion in large thin-walled components.

2.
Cureus ; 16(4): e58280, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38752078

RESUMEN

To achieve a positive functional prognosis in orthopedic surgery, particularly in shoulder surgeries, effective rehabilitation is essential. Recently, there has been growing interest in the use of virtual reality (VR) in the field of orthopedics, particularly for preoperative education and training, as well as clinical and home-based rehabilitation. This report describes the process of developing an application utilizing Meta Quest 2 VR technology (Meta, CA, USA) for rehabilitation after shoulder surgery. This application assists patients in performing postoperative exercises at home by wearing VR equipment tailored to their postoperative weeks. The advantages of VR rehabilitation lie in overcoming the limitations of traditional rehabilitation methods and providing patients with a better rehabilitation experience. Moreover, automating the rehabilitation process and reducing patients' visits to clinics can lead to cost savings. This report raises expectations for the potential and scalability of VR utilization, extending beyond orthopedics to other fields. In addition, it anticipates that with better feedback and motivation, the rehabilitation effects for patients can be further enhanced.

3.
Medicina (Kaunas) ; 60(2)2024 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-38399552

RESUMEN

Background and Objectives: Posterior lumbar interbody fusion (PLIF) plays a crucial role in addressing various spinal disorders. The success of PLIF is contingent upon achieving bone fusion, as failure can lead to adverse clinical outcomes. Demineralized bone matrix (DBM) has emerged as a promising solution for promoting fusion due to its unique combination of osteoinductive and osteoconductive properties. This study aims to compare the effectiveness of three distinct DBMs (Exfuse®, Bongener®, and Bonfuse®) in achieving fusion rates in PLIF surgery. Materials and Methods: A retrospective review was conducted on 236 consecutive patients undergoing PLIF between September 2016 and February 2019. Patients over 50 years old with degenerative lumbar disease, receiving DBM, and following up for more than 12 months after surgery were included. Fusion was evaluated using the Bridwell grading system. Bridwell grades 1 and 2 were defined as 'fusion', while grades 3 and 4 were considered 'non-fusion.' Clinical outcomes were assessed using visual analog scale (VAS) scores for pain, the Oswestry disability index (ODI), and the European quality of life-5 (EQ-5D). Results: Fusion rates were 88.3% for Exfuse, 94.3% for Bongener, and 87.7% for Bonfuse, with no significant differences. All groups exhibited significant improvement in clinical outcomes at 12 months after surgery, but no significant differences were observed among the three groups. Conclusions: There were no significant differences in fusion rates and clinical outcomes among Exfuse, Bongener, and Bonfuse in PLIF surgery.


Asunto(s)
Enfermedades de la Columna Vertebral , Fusión Vertebral , Humanos , Persona de Mediana Edad , Matriz Ósea , Calidad de Vida , Vértebras Lumbares/cirugía , Estudios Retrospectivos , Resultado del Tratamiento
4.
Life (Basel) ; 13(12)2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-38137930

RESUMEN

(1) Background: Adult spinal deformity (ASD) surgery is known to improve clinical and radiological parameters; however, it may also cause more complications in elderly patients. The purpose of this study was to compare the outcomes of ASD surgery, specifically regarding pain, disability, and health-related quality of life (HRQOL) in patients aged 75 years and over and patients aged under 75 years; (2) Methods: A total of 151 patients who underwent ASD surgery between August 2014 and September 2020 were included. Patients were divided into two groups based on whether they are 75 years and over or under. Radiological parameters measured included sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence (PI)- lumbar lordosis (LL). Data were collected 3, 6, and 12 months after surgery; (3) Results: At 12 months postoperatively, visual analog scale (VAS) for low back pain (p = 0.342), Oswestry disability index (ODI) (p = 0.087), and EuroQol 5-Dimensions (EQ-5D) (p = 0.125) did not differ between patients under 75 years and those 75 and above 75 group. PT (p = 0.675), PI-LL (p = 0.948), and SVA (p = 0.108) did not differ significantly 12 months after surgery in the two groups. In the entire patient group, compared to preoperative data, significant improvements were demonstrated for clinical and radiological parameters 12 months after surgery (all p < 0.001). The rate of medical complications did not correlate with age, but the rates of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) did (p = 0.638, p < 0.001, and p = 0.001, respectively); (4) Conclusions: In terms of clinical and radiological improvements, ASD surgery should be considered for patients regardless of whether they are younger than or older than 75 years. The clinical and radiological improvements and the risk of complications and revision surgeries must be considered in ASD patients who are 75 years or older.

5.
Nat Cancer ; 4(10): 1508-1525, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37723306

RESUMEN

The PDCD1-encoded immune checkpoint receptor PD-1 is a key tumor suppressor in T cells that is recurrently inactivated in T cell non-Hodgkin lymphomas (T-NHLs). The highest frequencies of PDCD1 deletions are detected in advanced disease, predicting inferior prognosis. However, the tumor-suppressive mechanisms of PD-1 signaling remain unknown. Here, using tractable mouse models for T-NHL and primary patient samples, we demonstrate that PD-1 signaling suppresses T cell malignancy by restricting glycolytic energy and acetyl coenzyme A (CoA) production. In addition, PD-1 inactivation enforces ATP citrate lyase (ACLY) activity, which generates extramitochondrial acetyl-CoA for histone acetylation to enable hyperactivity of activating protein 1 (AP-1) transcription factors. Conversely, pharmacological ACLY inhibition impedes aberrant AP-1 signaling in PD-1-deficient T-NHLs and is toxic to these cancers. Our data uncover genotype-specific vulnerabilities in PDCD1-mutated T-NHL and identify PD-1 as regulator of AP-1 activity.


Asunto(s)
Linfoma de Células T Periférico , Linfoma de Células T , Ratones , Animales , Humanos , Factor de Transcripción AP-1/genética , Factor de Transcripción AP-1/metabolismo , Receptor de Muerte Celular Programada 1/genética , Receptor de Muerte Celular Programada 1/metabolismo , Linfoma de Células T/genética , Genes Supresores de Tumor , Acetilcoenzima A/metabolismo , Glucólisis/genética
6.
Bone Joint Res ; 12(8): 497-503, 2023 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-37582511

RESUMEN

Aims: Focal knee arthroplasty is an attractive alternative to knee arthroplasty for young patients because it allows preservation of a large amount of bone for potential revisions. However, the mechanical behaviour of cartilage has not yet been investigated because it is challenging to evaluate in vivo contact areas, pressure, and deformations from metal implants. Therefore, this study aimed to determine the contact pressure in the tibiofemoral joint with a focal knee arthroplasty using a finite element model. Methods: The mechanical behaviour of the cartilage surrounding a metal implant was evaluated using finite element analysis. We modelled focal knee arthroplasty with placement flush, 0.5 mm deep, or protruding 0.5 mm with regard to the level of the surrounding cartilage. We compared contact stress and pressure for bone, implant, and cartilage under static loading conditions. Results: Contact stress on medial and lateral femoral and tibial cartilages increased and decreased, respectively, the most and the least in the protruding model compared to the intact model. The deep model exhibited the closest tibiofemoral contact stress to the intact model. In addition, the deep model demonstrated load sharing between the bone and the implant, while the protruding and flush model showed stress shielding. The data revealed that resurfacing with a focal knee arthroplasty does not cause increased contact pressure with deep implantation. However, protruding implantation leads to increased contact pressure, decreased bone stress, and biomechanical disadvantage in an in vivo application. Conclusion: These results show that it is preferable to leave an edge slightly deep rather than flush and protruding.

7.
Biomed Mater Eng ; 33(3): 195-207, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35527540

RESUMEN

BACKGROUND: Recently, there has been an increasing interest in mobile-bearing total knee arthroplasty (TKA). However, changes in biomechanics for femoral component alignment in mobile-bearing TKA have not been explored in depth. OBJECTIVE: This study aims to evaluate the biomechanical effect of sagittal alignment of the femoral component in mobile-bearing TKA. METHODS: We developed femoral sagittal alignment models with -3°, 0°, 3°, 5°, and 7° flexion. We also examine the kinematics of the tibiofemoral (TF) joint, contact point on the TF joint, contact stress on the patellofemoral (PF) joint, collateral ligament force, and quadriceps force using a validated computational model under a deep-knee-bend condition. RESULTS: Posterior kinematics of the TF joint increases as the femoral component flexes. The contact stress on the PF joint, collateral ligament force, and the quadriceps force decreases as the femoral component flexes. CONCLUSIONS: Our results show that a slight, approximately 0°âˆ¼3°, flexion of the implantation could be an effective substitute technique. However, excessive flexion should be avoided because of the potential loosening of the TF joint.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Fenómenos Biomecánicos , Simulación por Computador , Fémur/diagnóstico por imagen , Fémur/cirugía , Análisis de Elementos Finitos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Rango del Movimiento Articular , Tibia/cirugía
8.
Blood ; 138(14): 1225-1236, 2021 10 07.
Artículo en Inglés | MEDLINE | ID: mdl-34115827

RESUMEN

Cutaneous T-cell lymphomas (CTCLs) are a clinically heterogeneous collection of lymphomas of the skin-homing T cell. To identify molecular drivers of disease phenotypes, we assembled representative samples of CTCLs from patients with diverse disease subtypes and stages. Via DNA/RNA-sequencing, immunophenotyping, and ex vivo functional assays, we identified the landscape of putative driver genes, elucidated genetic relationships between CTCLs across disease stages, and inferred molecular subtypes in patients with stage-matched leukemic disease. Collectively, our analysis identified 86 putative driver genes, including 19 genes not previously implicated in this disease. Two mutations have never been described in any cancer. Functionally, multiple mutations augment T-cell receptor-dependent proliferation, highlighting the importance of this pathway in lymphomagenesis. To identify putative genetic causes of disease heterogeneity, we examined the distribution of driver genes across clinical cohorts. There are broad similarities across disease stages. Many driver genes are shared by mycosis fungoides (MF) and Sezary syndrome (SS). However, there are significantly more structural variants in leukemic disease, leading to highly recurrent deletions of putative tumor suppressors that are uncommon in early-stage skin-centered MF. For example, TP53 is deleted in 7% and 87% of MF and SS, respectively. In both human and mouse samples, PD1 mutations drive aggressive behavior. PD1 wild-type lymphomas show features of T-cell exhaustion. PD1 deletions are sufficient to reverse the exhaustion phenotype, promote a FOXM1-driven transcriptional signature, and predict significantly worse survival. Collectively, our findings clarify CTCL genetics and provide novel insights into pathways that drive diverse disease phenotypes.


Asunto(s)
Linfoma Cutáneo de Células T/genética , Transcriptoma , Animales , Células Cultivadas , Proteína Forkhead Box M1/genética , Regulación Neoplásica de la Expresión Génica , Genes Supresores de Tumor , Humanos , Ratones , Mutación , Oncogenes , Proteína p53 Supresora de Tumor/genética
9.
J Orthop Surg Res ; 15(1): 603, 2020 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-33308249

RESUMEN

BACKGROUND: Although several reference axes have been established for determining femoral rotational alignment during total knee arthroplasty (TKA), the most accurate axis is undetermined. This study determines the relationship between the posterior cortical axis (PCA) and the trochlear anterior line (TAL) of the femur in relation to the epicondylar axis. METHODS: A total of 341 patients who underwent TKA for osteoarthritis were enrolled. Patients who had undergone previous bony surgery or replacement that might have changed the femoral geometry were excluded. Finally, 336 patients (200 females and 136 males) were included in the study. The angles between the transepicondylar axis (TEA) and TAL and TEA and the femoral PCA (FPCA) were evaluated. We also assessed whether there was any significant differences in variance and gender in these two angles. Student's t tests were used to determine the significance of coronal alignment and any gender-based differences. The variances between the TAL/TEA and FPCA/TEA angles were compared using F tests. RESULTS: The FPCA was externally rotated by 2.6° ± 3.6°, and the trochlear anterior line was internally rotated by 5.2° ± 5.5°, relative to the TEA. Gender-based differences were observed in the comparisons between anatomical references and TEA. CONCLUSIONS: The FPCA is a more conservative landmark than the TAL for intraoperative or postoperative approximation of the TEA. When conventional reference axes, such as the posterior condylar axis and the anteroposterior axis, are inaccurate, surgeons can refer to this alternative reference. These findings demonstrate that the FPCA may be useful for determining the rotational alignment of the femoral component before and during TKA.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/métodos , Fémur/cirugía , Articulación de la Rodilla/cirugía , Prótesis de la Rodilla , Osteoartritis de la Rodilla/cirugía , Anciano , Femenino , Fémur/fisiopatología , Humanos , Articulación de la Rodilla/fisiopatología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteoartritis de la Rodilla/fisiopatología , Rango del Movimiento Articular , República de Corea , Rotación , Caracteres Sexuales
10.
J Orthop Surg Res ; 15(1): 499, 2020 Oct 29.
Artículo en Inglés | MEDLINE | ID: mdl-33121532

RESUMEN

PURPOSE: Surgical techniques for total knee arthroplasty (TKA) require femoral rotational corrections that alter the position of the surface of the posterior femoral joint especially in kinematic alignment. However, preoperative planning of TKA based on computed tomography (CT), without knowing the femoral cartilage thickness, may cause post-surgery failures in femoral rotation. Therefore, this study aimed to evaluate the effects of posterior condyle cartilage thickness on rotational alignment in the femoral component. METHODS: Three-dimensional magnetic resonance imaging (MRI) scans were obtained for 139 male and 531 female osteoarthritis patients. The angles defined by the femoral posterior condylar axis (PCA) and the surgical transepicondylar axis (TEA) were evaluated with respect to the presence of cartilage. Additionally, these effects were evaluated with respect to patient gender and varus/valgus condition. RESULTS: In all patients, the angle between the TEA and PCA was significantly greater in the presence of cartilage than in the absence of cartilage. This result was also seen in female patients. However, there was no difference in the TEA/PCA angle in male patients based on the presence of cartilage. The TEA/PCA angle was significantly greater in the presence of cartilage than in the absence of cartilage in the female varus group. However, there were no differences in the TEA/PCA angle based on the presence of cartilage in the male varus/valgus and female valgus groups. Cartilage thickness in the posterior femoral condyle was significantly greater on the lateral side than on the medial side in all and male patients. However, there was no difference between the genders regarding cartilage thickness. CONCLUSION: Surgical planning for TKA based on CT does not consider articular cartilage and could lead to external malrotation of the femoral implant. Therefore, the effect of the remaining posterior condylar cartilage should be considered by surgeons to prevent over-rotation of the femoral component, especially in female varus knees.


Asunto(s)
Desviación Ósea/fisiopatología , Desviación Ósea/cirugía , Cartílago Articular/cirugía , Fémur/fisiopatología , Fémur/cirugía , Articulación de la Rodilla/cirugía , Osteoartritis de la Rodilla/cirugía , Rotación , Anciano , Artroplastia de Reemplazo de Rodilla/métodos , Desviación Ósea/diagnóstico por imagen , Cartílago Articular/diagnóstico por imagen , Cartílago Articular/patología , Femenino , Fémur/diagnóstico por imagen , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteoartritis de la Rodilla/patología , Caracteres Sexuales , Tomografía Computarizada por Rayos X
11.
Pain Res Manag ; 2020: 6294151, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32351640

RESUMEN

Purpose: The purpose of this study was to investigate the prevalence of sleep disturbance and its clinical implication in patients with ASD. Methods: A total of 44 patients with ASD and 137 patients with lumbar spinal stenosis (LSS) were enrolled in the study. Forty four patients were selected from the LSS group after propensity score matching. Global Pittsburgh Sleep Quality Index (PSQI) score, demographic data, visual analog scale (VAS) score for back and leg pain, Oswestry Disability Index (ODI), and EuroQol 5-dimension questionnaire (EQ-5D) were compared between both groups. Multiple regression analysis was performed with VAS for back pain as the dependent variable and age, sex, PSQI, and VAS for leg pain as the independent variables in the ASD group. Results: 33 (75.0%) and 32 (72.7%) patients were classified as poor sleepers in the ASD group and the LSS group, respectively. In the ASD group, the VAS score for back pain was 7.7 ± 1.7 in the poor sleeper group and 5.6 ± 2.2 in the nonpoor sleeper group. In the LSS group, poor sleep quality was associated with the ODI score, ODI score without a sleep component, and EQ-5D. The regression model for predicting VAS for back pain in the ASD group suggested that poor sleep quality and increased leg pain were associated with increased back pain. Conclusions: Because sleep quality is a critical factor in augmenting back pain in patients with ASD, this study underlines the need to investigate sleep quality during the routine examination of patients with ASD.


Asunto(s)
Trastornos del Sueño-Vigilia/epidemiología , Trastornos del Sueño-Vigilia/etiología , Curvaturas de la Columna Vertebral/complicaciones , Estenosis Espinal/complicaciones , Anciano , Anciano de 80 o más Años , Estudios Transversales , Femenino , Humanos , Vértebras Lumbares , Masculino , Prevalencia , Encuestas y Cuestionarios
12.
Surg Radiol Anat ; 42(10): 1231-1236, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32405786

RESUMEN

The importance of femoral sagittal bowing on total knee arthroplasty (TKA) has not been actively discussed. Femoral sagittal bowing can lead to cortex damage, fractures, or femoral malalignment. Therefore, the purpose of this study was to evaluate femoral sagittal bowing at different segments of the femur in the Korean population, and to discuss the implications on total knee arthroplasty. Differences in the morphology of femoral sagittal bowing for 978 patients-829 women and 148 men-were evaluated using magnetic resonance imaging. The angle between the femoral mechanical axis and the anterior cortex line was measured for all the patients. In addition, the gender difference in femoral sagittal bowing was investigated. The angle of femoral sagittal bowing with the mechanical axis was 2.8˚ ± 2.2˚. The angles for femoral sagittal bowing were 2.9˚ ± 2.2˚ and 2.3˚ ± 2.6˚ for females and males, respectively. Thus, a gender difference was found in the femoral sagittal bowing (p < 0.05). Excessive sagittal bowing of the femur can affect the final sagittal position of the femoral component, and this has implications for implant design selection. We recommend that surgeons accurately perform pre-operative evaluation of femoral bowing to prevent potential malalignment, rotation, and abnormal stresses between the femur and implant.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/instrumentación , Fémur/anatomía & histología , Imagen por Resonancia Magnética , Diseño de Prótesis , Anciano , Artroplastia de Reemplazo de Rodilla/efectos adversos , Desviación Ósea/etiología , Desviación Ósea/prevención & control , Femenino , Fémur/diagnóstico por imagen , Fémur/cirugía , Humanos , Prótesis de la Rodilla/efectos adversos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/prevención & control , Cuidados Preoperatorios/métodos , República de Corea , Factores Sexuales
13.
Nat Commun ; 11(1): 1806, 2020 04 14.
Artículo en Inglés | MEDLINE | ID: mdl-32286303

RESUMEN

Primary cutaneous γδ T cell lymphomas (PCGDTLs) represent a heterogeneous group of uncommon but aggressive cancers. Herein, we perform genome-wide DNA, RNA, and T cell receptor (TCR) sequencing on 29 cutaneous γδ lymphomas. We find that PCGDTLs are not uniformly derived from Vδ2 cells. Instead, the cell-of-origin depends on the tissue compartment from which the lymphomas are derived. Lymphomas arising from the outer layer of skin are derived from Vδ1 cells, the predominant γδ cell in the epidermis and dermis. In contrast, panniculitic lymphomas arise from Vδ2 cells, the predominant γδ T cell in the fat. We also show that TCR chain usage is non-random, suggesting common antigens for Vδ1 and Vδ2 lymphomas respectively. In addition, Vδ1 and Vδ2 PCGDTLs harbor similar genomic landscapes with potentially targetable oncogenic mutations in the JAK/STAT, MAPK, MYC, and chromatin modification pathways. Collectively, these findings suggest a paradigm for classifying, staging, and treating these diseases.


Asunto(s)
Linfoma Cutáneo de Células T/genética , Linfoma Cutáneo de Células T/patología , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Secuencia de Aminoácidos , Antígenos CD1d/metabolismo , Ensamble y Desensamble de Cromatina , Epítopos/inmunología , Genoma Humano , Células HEK293 , Humanos , Ganglios Linfáticos/patología , Modelos Biológicos , Mutación/genética , Fenotipo , Análisis de Componente Principal , Transducción de Señal , Piel/patología , Transcripción Genética , Transcriptoma/genética
14.
J Orthop Surg Res ; 15(1): 24, 2020 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-31969195

RESUMEN

BACKGROUND: Articular surface curvature design is important in tibiofemoral kinematics and the contact mechanics of total knee arthroplasty (TKA). Thus far, the effects of articular surface curvature have not been adequately discussed with respect to conforming, nonconforming, and medial pivot designs in patient-specific TKA. Therefore, this study evaluates the underlying relationship between the articular surface curvature geometry and the wear performance in patient-specific TKA. METHODS: We compare the wear performances between conventional and patient-specific TKA under gait loading conditions using a computational simulation. Patient-specific TKAs investigated in the study are categorized into patient-specific TKA with conforming articular surfaces, medial pivot patient-specific TKA, and bio-mimetic patient-specific TKA with a patient's own tibial and femoral anatomy. The geometries of the femoral components in patient-specific TKAs are identical. RESULTS: The anterior-posterior and internal-external kinematics change with respect to different TKA designs. Moreover, the contact pressure and area did not directly affect the wear performance. In particular, conforming patient-specific TKAs exhibit the highest volumetric wear and wear rate. The volumetric wear in a conforming patient-specific TKA is 29% greater than that in a medial pivot patient-specific TKA. CONCLUSION: The findings in this study highlight that conformity changes in the femoral and tibial inserts influence the wear performance in patient-specific TKA. Kinematics and contact parameters should be considered to improve wear performance in patient-specific TKA. The conformity modification in the tibiofemoral joint changes the kinematics and contact parameters, and this affects wear performance.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/instrumentación , Prótesis de la Rodilla/estadística & datos numéricos , Modelos Teóricos , Medicina de Precisión/estadística & datos numéricos , Diseño de Prótesis/estadística & datos numéricos , Fenómenos Biomecánicos , Simulación por Computador , Análisis de Elementos Finitos , Humanos , Medicina de Precisión/instrumentación
15.
Artículo en Inglés | MEDLINE | ID: mdl-31035391

RESUMEN

There is now strong evidence that radiofrequency electromagnetic field (RF-EMF) exposure influences the human electroencephalogram (EEG). While effects on the alpha band of the resting EEG have been repeatedly shown, the mechanisms underlying that effect have not been established. The current study used well-controlled methods to assess the RF-EMF exposure effect on the EEG and determine whether that effect might be thermally mediated. Thirty-six healthy adults participated in a randomized, double-blind, counterbalanced provocation study. A water-perfusion suit (34 C) was worn throughout the study to negate environmental influences and stabilize skin temperature. Participants attended the laboratory on four occasions, the first being a calibration session and the three subsequent ones being exposure sessions. During each exposure session, EEG and skin temperature (8 sites) were recorded continuously during a baseline phase, and then during a 30 min exposure to a 920 MHz GSM-like signal (Sham, Low RF-EMF (1 W/kg) and High RF-EMF (2 W/kg)). Consistent with previous research, alpha EEG activity increased during the High exposure condition compared to the Sham condition. As a measure of thermoregulatory activation, finger temperature was found to be higher during both exposure conditions compared to the Sham condition, indicating for the first time that the effect on the EEG is accompanied by thermoregulatory changes and suggesting that the effect of RF-EMF on the EEG is consistent with a thermal mechanism.


Asunto(s)
Electroencefalografía/métodos , Campos Electromagnéticos , Ondas de Radio , Adolescente , Adulto , Presión Sanguínea/efectos de la radiación , Teléfono Celular , Método Doble Ciego , Femenino , Humanos , Persona de Mediana Edad , Descanso , Temperatura Cutánea/efectos de la radiación , Adulto Joven
16.
Biomed Mater Eng ; 30(2): 133-144, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30741662

RESUMEN

BACKGROUND: The effects of the posterior slope of the tibial prosthesis on unicompartmental knee arthroplasty have not been fully evaluated and controversies still exist. OBJECTIVE: This study evaluates the effects of the posterior slope of the tibia on contact stresses in polyethylene inserts and articular cartilage using finite element analysis. METHODS: We generated a computational model followed by the development of a posterior tibial slope (PTS) from -1° to 15° cases with increments of 2° PTS models. Using a validated finite element (FE) model, we investigated the influence of the changes in PTS on the contact stress in the medial polyethylene insert and lateral cartilage. The FE model's loading condition is level walking, a normal daily activity. RESULTS: The contact stress increased on the lateral articular cartilage as the PTS increased. The contact stress on the polyethylene insert differed from the contact stress on the lateral articular cartilage, and it generally increased as the PTS decreased. However, in the initial stance phase when an axial force was exerted, it increased as the PTS increased. CONCLUSIONS: Our results show that an offset of ±2° from the initial anatomical tibial slope does not biomechanically affect the outcome.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Articulación de la Rodilla/anatomía & histología , Tibia/anatomía & histología , Fenómenos Biomecánicos , Simulación por Computador , Análisis de Elementos Finitos , Humanos , Articulación de la Rodilla/fisiología , Articulación de la Rodilla/cirugía , Prótesis de la Rodilla , Modelos Anatómicos , Polietileno/química , Rango del Movimiento Articular , Estrés Mecánico , Tibia/fisiología , Tibia/cirugía
17.
Biomed Mater Eng ; 30(2): 171-182, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30741665

RESUMEN

BACKGROUND: Component malalignment in unicompartmental knee arthroplasty (UKA) has been related to the concentration in tibiofemoral joint of contact stress and to poor post-operative outcomes. Few studies investigated a biomechanical effect of femur component position in sagittal plane. The purpose of this study was to evaluate the biomechanical effect of the femoral components on the sagittal alignment under flexion and extension conditions using computational simulations. METHODS: The flexion and extension conditions of the femoral component were analyzed from 10° extension to 10° flexion in 1° increments. We considered the contact stresses in the polyethylene (PE) inserts and articular cartilage, and the force on the collateral ligament, under gait cycle conditions. RESULTS: The contact stress on the PE insert increased as flexion of the femoral component increased, but there was not a remarkable difference in the amount of increased contact stress upon extension. There was no difference in the contact stress on the articular cartilage upon extension of the femoral component, but it increased in flexion during stance and double support periods. The forces on the medial collateral ligaments increased with the extension and decreased with the flexion of the femoral component, whereas the forces on the lateral collateral ligaments showed opposite trends. CONCLUSIONS: Surgeons should be concerned with femoral component position on UKA not only in frontal plane but also in the sagittal plane, because flexion or extension of the femoral component may impact the PE or opposite compartment along with the surrounding ligaments around knee joint.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Fémur/fisiología , Articulación de la Rodilla/fisiología , Prótesis de la Rodilla , Adulto , Fenómenos Biomecánicos , Simulación por Computador , Fémur/anatomía & histología , Humanos , Articulación de la Rodilla/anatomía & histología , Masculino , Modelos Anatómicos , Modelos Biológicos , Polietileno/química , Rango del Movimiento Articular , Estrés Mecánico
18.
J Therm Biol ; 79: 1-7, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30612669

RESUMEN

People are exposed to heat regularly due to their jobs or daily habits in cold winter, but few studies have reported whether parallel heat and cold exposure and diminish cold acclimation. This study was conducted to investigate the effects of alternating exposure to cold and heat on cold tolerance in eight young males. A daily acclimation program to cold and heat, which consisted of 2-h sitting at 10 °C air in the morning and 2-h running and rest at 30 °C air in the afternoon, was conducted for 14 consecutive days. Eight male subjects participated in a cold tolerance test (10 °C [ ±â€¯0.3], 40%RH[ ±â€¯3]) before (PRE) and after (POST) completing the alternating exposure program. During the cold tolerance test, subjects remained sitting upright on a chair for 60 min. Rectal temperature (Tre) was lower in POST than in PRE during the 60-min cold tolerance test (P = 0.027). During the cold tolerance test, systolic, diastolic, and mean arterial blood pressures in POST were lower than those in PRE (P = 0.006, P = 0.005, and P = 0.004). No significant differences in skin temperatures between PRE and POST were found for the cold tolerance test. There were no significant differences in energy expenditure during cold exposure between PRE and POST. Subjects felt less cold in POST than in PRE (P = 0.013) whereas there was no significant difference in overall thermal comfort between PRE and POST. These results suggest that cold adaptation can still occur in the presence of heat stress.


Asunto(s)
Aclimatación/fisiología , Regulación de la Temperatura Corporal , Frío , Adulto , Presión Sanguínea , Respuesta al Choque por Frío , Metabolismo Energético , Respuesta al Choque Térmico , Humanos , Masculino
19.
PLoS One ; 13(11): e0207925, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30485344

RESUMEN

OBJECTIVE: To assess the feasibility of the menstrual cup for short-term management of urinary leakage among women with vesicovaginal fistula (VVF). METHODS: A repeated measures design compared volume of leakage with and without the cup via a 2-hr pad test among women with VVF seeking surgical repair at a health facility in Ghana. Subsequently a gynecological exam was administered to assess safety outcomes, followed by a questionnaire to assess acceptability and perceived efficacy. A paired t-test was used to analyze reduction of leakage in ml, and percent reduction was reported. Study limitations include observer bias while evaluating adverse outcomes and the possibility of social desirability bias during questionnaire administration that might overestimate the effect of the cup and women's acceptability. RESULTS: Of the 32 patients screened, 11 were eligible (100% consent rate). At baseline, mean (±SD) leakage in ml was 63.2 (±49.2) (95% CI: 30.2-96.3) over two hours, while the mean leakage over two hours of use of the cup was 16.8 (±16.5) (95% CI: 5.7-27.9). The mean difference of 46.4 (±52.1) ml with use of the cup (95% CI: 11.4-81.4) was statistically significant (p = 0.02). With the cup, women experienced an average 61.0% (±37.4) (95% CI: 35.9-86.2) leakage reduction, a difference 10/11 users (91.0%) perceived in reduced leakage. One participant, reporting four previous surgical attempts, experienced a 78.7% leakage reduction. Acceptability was high-women could easily insert (8/11), remove (8/11), and comfortably wear (11/11) the cup and most (10/11) would recommend it. No adverse effects attributable to the intervention were observed on exam, although some women perceived difficulties with insertion and removal. Data collection tools were appropriate with slight modification advised. CONCLUSION: A larger trial is warranted for a more robust evaluation of the menstrual cup for management of urinary leakage due to VVF among women who have not yet accessed surgery or for whom surgery was not successful.


Asunto(s)
Productos para la Higiene Menstrual , Incontinencia Urinaria/terapia , Fístula Vesicovaginal/terapia , Adulto , Anciano , Estudios de Factibilidad , Femenino , Ghana , Instituciones de Salud , Humanos , Persona de Mediana Edad , Aceptación de la Atención de Salud , Cuidados Preoperatorios , Resultado del Tratamiento
20.
J Strength Cond Res ; 32(3): 700-707, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29239981

RESUMEN

Burdon, CA, Park, J, Tagami, K, Groeller, H, and Sampson, JA. Effect of practice on performance and pacing strategies during an exercise circuit involving load carriage. J Strength Cond Res 32(3): 700-707, 2018-Pacing is critical for athletic endeavors, and the strategies used by athletes are often modified after practice. The importance of practice when completing occupational assessments has been established; however, the effect of load carriage and discrete subtask activities on strategies to modulate physical exertion to complete a work task simulation is currently unknown. Therefore, we sought to investigate the effect of practice on pacing strategies used to complete a physiological aptitude assessment circuit. Twenty-five participants completed an assessment designed for firefighters on 3 occasions. The circuit comprised 6 disparate tasks (including unilateral load carriage, static holds and fire-hose drags) with lap and task completion times recorded. Pacing strategies were examined relative to the effect of practice throughout (globally) and within the assessment (discrete tasks). By the second visit, overall test performance and discrete task performance of the first, fourth, and fifth tasks improved, respectively, by 12.6% (95% confidence interval: ±3.6%, p < 0.01), 12.4% (±6.0%, p < 0.01), 11.7% (±4.9%, p < 0.01), and 17.8% (±10.0%, p < 0.03). Compared with visit 1, significant improvements in performance were observed on the second and third visit. However, no significant additional improvement was noted between visits 2 and 3. Therefore, to reliably assess performance of the occupational test, 1 practice session (2 visits) is required. Practice is important to allow individuals to optimize their pacing strategy for successful performance.


Asunto(s)
Atletas , Rendimiento Atlético/fisiología , Soporte de Peso/fisiología , Adolescente , Adulto , Ejercicio Físico , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Esfuerzo Físico , Adulto Joven
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