Publicação
Proposal of a pre-clinical test to assess the biomechanical performance of shoulder prostheses
| Resumo: | Prosthesis commercialization requires the compliance of regulations that ensure the safe use of prosthesis. However, several prostheses have been withdrawn from the market due to their high failure rates, which is a strong indicator of the lack of suitable pre-clinical tests that allow a more rigorous evaluation of its performance and effectiveness. Thus, the main objective of this doctoral thesis consisted in the development of a pre-clinical test capable of accessing shoulder prosthesis performance. For this purpose, a multi-body model of the intact shoulder containing all muscle groups was used in the first stage in view to identify and characterize those that most contribute to the 90º abduction movement, being them the deltoid, the infraspinatus, the supraspinatus and the subscapularis. Two in vitro models were constructed using composite bone structures of the humerus and of the scapula. In the intact model the cartilage and the inferior glenohumeral ligament were considered and in the implanted model a non-cemented anatomical prosthesis (Comprehensive® Total Shoulder System) and a central post in porous metal for glenoid fixation were used. Strain gage rosettes were used to measure the deformation suffered by the bone structures when positioned at 90º abduction and subjected to loading. Finite element models (FEM) of the intact and implanted shoulder, that replicate the in vitro models, were developed. The FEM were subjected to the same loading scenarios as the in vitro models. The comparison between the strains determined numerically and experimentally allowed FEM validation. Stress and strain distribution inside the bone structures, determined with the FEM of the implanted shoulder, agree with the clinical observations present in literature. This indicates that, in a general way, the developed FEM predicts bone behavior in the presence of a prosthesis and may be considered a pre-clinical test to evaluate shoulder implants performance. To verify that the pre-clinical test developed is sensitive to small differences in implant design and that can be used to predict shoulder prosthesis performance, a new central fixation post in polyethylene was used. Stress and strain distributions determined using the FEM with the new fixation post are (once again) in agreement with clinical observations, confirming that the developed FEM can be used for the pre-clinical evaluation of other shoulder implant designs, allowing to analyze their performance before clinical use. |
|---|---|
| Autores principais: | Bola, Ana Margarida Ramos |
| Assunto: | Engenharia mecânica Biomecânica Próteses articulares - Ombro Deformações mecânicas |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Prosthesis commercialization requires the compliance of regulations that ensure the safe use of prosthesis. However, several prostheses have been withdrawn from the market due to their high failure rates, which is a strong indicator of the lack of suitable pre-clinical tests that allow a more rigorous evaluation of its performance and effectiveness. Thus, the main objective of this doctoral thesis consisted in the development of a pre-clinical test capable of accessing shoulder prosthesis performance. For this purpose, a multi-body model of the intact shoulder containing all muscle groups was used in the first stage in view to identify and characterize those that most contribute to the 90º abduction movement, being them the deltoid, the infraspinatus, the supraspinatus and the subscapularis. Two in vitro models were constructed using composite bone structures of the humerus and of the scapula. In the intact model the cartilage and the inferior glenohumeral ligament were considered and in the implanted model a non-cemented anatomical prosthesis (Comprehensive® Total Shoulder System) and a central post in porous metal for glenoid fixation were used. Strain gage rosettes were used to measure the deformation suffered by the bone structures when positioned at 90º abduction and subjected to loading. Finite element models (FEM) of the intact and implanted shoulder, that replicate the in vitro models, were developed. The FEM were subjected to the same loading scenarios as the in vitro models. The comparison between the strains determined numerically and experimentally allowed FEM validation. Stress and strain distribution inside the bone structures, determined with the FEM of the implanted shoulder, agree with the clinical observations present in literature. This indicates that, in a general way, the developed FEM predicts bone behavior in the presence of a prosthesis and may be considered a pre-clinical test to evaluate shoulder implants performance. To verify that the pre-clinical test developed is sensitive to small differences in implant design and that can be used to predict shoulder prosthesis performance, a new central fixation post in polyethylene was used. Stress and strain distributions determined using the FEM with the new fixation post are (once again) in agreement with clinical observations, confirming that the developed FEM can be used for the pre-clinical evaluation of other shoulder implant designs, allowing to analyze their performance before clinical use. |
|---|