Method for analysis of maximum allowable loads on osteointegration implant of exoprosthesis

Authors:

Shcherbina Konstantin Konstantinovich, Grand PhD in Medical sciences (Dr. Med. Sci), Deputy Director General — Director of the Institute of Prosthetics and Orthotics, Albrecht Federal Scientific and Educational Centre of Medical and Social Expertise and Rehabilitation, Bestuzhevskaya str., 50, St. Petersburg, 195067, Russian Federation, e-mail: shcherbina180@mail.ru; https://orcid.org/0000-0001-7579-0113

Sinegub Andrey Vladimirovich, Junior Researcher of the Department of Biomechanical Studies of the Musculoskeletal System of Institute of Prosthetics and Orthotics, Albrecht Federal Scientific and Educational Centre of Medical and Social Expertise and Rehabilitation, Bestuzhevskaya str., 50, St. Petersburg, 195067, Russian Federation; e-mail: a.sinegub@yandex.ru; https://orcid.org / 0000-0003-2619-3691.

Chernikova Marina Vladimirovna, Head of the Design Department of Institute of Prosthetics and Orthotics, Albrecht Federal Scientific and Educational Centre of Medical and Social Expertise and Rehabilitation, 50 Bestuzhevskaya str., St. Petersburg, 195067, Russian Federation; postgraduate student of Department of Automation and Control Processes, Saint Petersburg Electrotechnical University, Professora Popova Street, 5, 197022, Russian Federation; e-mail: chernikovamarinavl@gmail.com; https://orcid.org/0000-0002-3881-7521.

Fogt Elizaveta Vladimirovna, Head of the Department of Biomechanical Studies of the Musculoskeletal System of Institute of Prosthetics and Orthotics, Albrecht Federal Scientific and Educational Centre of Medical and Social Expertise and Rehabilitation, Bestuzhevskaya Street, 50, 195067, Saint Petersburg, Russian Federation; postgraduate student of Department of Biomedical Engineering, Saint Petersburg Electrotechnical University, Professora Popova Street, 5, 197022, Saint Petersburg, Russian Federation; e-mail: fogtlisbet11@yandex.ru; https://orcid.org/0000-0002-1017-6179.

Annotation:

Introduction. Amputation of the lower extremities has a negative impact not only on life expectancy, but also on its quality. A decrease in physical activity due to amputation leads to the loss of the disabled person himself from the social and professional sphere, which causes significant socio-economic losses of society as a whole. With the development of prosthetics technologies, an alternative method of fixing the prosthesis on the human body was developed — percutaneous osteointegrated prosthetics. This method consists in fixing the exoprosthesis by surgical implantation of a biocompatible metal device into the residual bone of the stump. The development of this technology is a promising direction of rehabilitation of a disabled person, improving the quality of his life, but imposes additional requirements for safe operation. Excessive loads exerted on the osteointegrated implant of the exoprosthesis increase the risks of bone fracture.

Aim. To propose a method of mathematical analysis of the maximum permissible loads on an osteointegrated implant of an exoprosthesis, taking into account the level of amputation.

Materials and methods. In this study, a digital model of an osteointegrated exoprosthesis implant was built using 3D-modeling technology. The critical states of the developed digital model simulating the main loads arising during the daily motor activity of a healthy person were studied by the finite element method, and objective technical results were obtained. To conduct the study, mathematical computer modeling was used using the following programs: Ansys 2020R2 (Ansys inc, USA); MSC Adams (Hexagon, USA), Materialise Mimics and Materialise 3-Matic (Materialise NV, Belgium).

Results. The results of mathematical modeling are presented, which indicate an increase in the peak moment on the implant from 600 Nm to 18070 Nm (short stump) and from 374 Nm to 12270 Nm (long stump) with an increase in the leg mach velocity from 0.087 rad/s to 1.05 rad/s.

Discussion. This study is the initial stage of the safety requirements development for osseointegrative method of fixing prostheses. The development of method for the analysis of limit loads will minimize the risks of complications in a real clinical situation.

Conclusion. The developed method based on the construction of a digital model can be used to design and configure safety systems for prostheses and determine the maximum permissible moments in the drives of mechatronic prostheses integrated into the musculoskeletal system.

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