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1.
BMC Musculoskelet Disord ; 15: 262, 2014 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-25095740

RESUMO

BACKGROUND: Due to the advantages of its bone-conserving nature, hip resurface arthroplasty (HRA) has recently gained the interest of orthopedic surgeons for the treatment of young and active patients who have osteonerosis of the femoral head. However, in long-term follow-up studies after HRA, narrowing of the femoral neck has often been found, which may lead to fracture. This phenomenon has been attributed to the stress alteration (stress shielding). Studies addressing the effects of necrotic size and the orientation of the implant on stress alterations are lacking. METHODS: Computed tomography images of a standard composite femur were used to create a three-dimensional finite-element (FE) intact femur model. Based on the intact model, FE models simulating four different levels of necrotic regions (0°, 60°, 100°, 115°) and three different implant insertion angles (varus 10°, neutral, valgus 10°) were created. The von Mises stress distributions and the displacement of the stem tip of each model were analyzed and compared for loading conditions that simulated a single-legged stance. RESULTS: Stress shielding occurred at the femoral neck after HRA. More severe stress shielding and an increased displacement of the stem tip were found for femoral heads that had a wider necrotic lesion. From a biomechanics perspective, the results were consistent with clinical evidence of femoral neck narrowing after HRA. In addition, a varus orientation of the implant resulted in a larger displacement of the stem tip, which could lead to an increased risk of implant loosening. CONCLUSIONS: A femoral head with a wide necrotic lesion combined with a varus orientation of the prosthesis increases the risk of femoral neck narrowing and implant loosening following HRA.


Assuntos
Artroplastia de Quadril/instrumentação , Simulação por Computador , Necrose da Cabeça do Fêmur/cirurgia , Análise de Elementos Finitos , Prótese de Quadril , Modelos Anatômicos , Artroplastia de Quadril/efeitos adversos , Fenômenos Biomecânicos , Necrose da Cabeça do Fêmur/diagnóstico por imagem , Necrose da Cabeça do Fêmur/fisiopatologia , Humanos , Desenho de Prótese , Falha de Prótese , Estresse Mecânico , Tomografia Computadorizada por Raios X , Resultado do Tratamento
2.
Healthcare (Basel) ; 9(1)2021 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-33477488

RESUMO

This study examined the relationships among self-reported health, daily positive mood, and daily emotional exhaustion among employees in health and fitness clubs using residual dynamic structural equation modeling (RDSEM). A questionnaire was completed by 179 employees at recruitment and then a diary survey over 10 consecutive workdays. Results of RDSEM analyses revealed that daily positive mood was negatively associated with daily emotional exhaustion at both within-person and between-person levels. Self-reported health was positively related to the person's mean of daily positive mood and negatively associated with the person's mean of daily emotional exhaustion. Self-reported health moderated the relationship between daily positive mood and daily emotional exhaustion; employees with higher self-reported health levels tend to respond with larger changes in their daily emotional exhaustion when their daily positive mood changes. These findings provide important insights for organizations aiming at their employees' health, happiness, and job burnout.

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