A test of a customized implant for hip replacement

December 13, 2019

A team of scientists from the Advanced Manufacturing Technologies Center of the National Technology Initiative (NTI) of Peter the Great St.Petersburg Polytechnic University (SPbPU) (head -- Prof. A.I. Borovkov, the Vice-rector for Advanced Projects of Peter the Great St. Petersburg Polytechnic University) developed a mathematical model of an "endoprosthesis-skeleton" system. Special attention was paid to the geometry and internal structure of hip bones. Using advanced computer modeling technologies, the team assessed the integrity of the biomechanical structure for a typical case (a patient standing on two legs). Currently the team is working on a methodology that would reduce the time of such analysis to several days. The results of the study were published in the Vibroengineering PROCEDIA journal and presented at the 12th All-Russia Congress on Fundamental Issues of Theoretical and Applied Mechanics.

Hip joint arthroplasty is a relatively common procedure today. During arthroplasty the upper part of a patient's hip bone is replaced with a metal stem with a spherical joint element, and a cup to allow the head of the joint to rotate inside the pelvis. Medical companies manufacture standard elements with different parameters for ordinary hip replacement operations. However, after some time a certain share of patients experiences issues with implants and requires their replacement. As a rule, this happens due to the insufficient (or excessive) load the endoprosthesis puts on the hip bone causing its tissue to change. Moreover, bone strength can be affected by osteoporosis and other diseases. By the time of the second surgery (the removal of the initial implant and the installation of a revision one) a part of the hip bone becomes unfit as it is unable to bear the load. Therefore, when a patient comes to a secondary operation with a damaged hip bone, standard implants are of no use for them, and a regular cup (even if it is of a bigger size) might not work.

The manufacturers produce special sets of elements that can be combined with each other in different ways to be used in revision operations as well as in patients with compound fractures or cancer. However, such surgeries have high risk rates: any issue with a revision structure or additional bone tissue loss may cause grave health issues. It is extremely important to understand if the prosthesis is able to bear the load, and if the damage to the patient's bone can be avoided. Virtual testing before installation could help eliminate numerous post-surgical complications. However, there is currently no universal assessment method to do so. It takes a long time to build a model on the basis of bone CT results, while the patient's health parameters keep constantly changing. Therefore, the window between diagnostics and the surgery should be as short as possible.

A team of engineers from the Advanced Manufacturing Technologies Center of the National Technology Initiative (NTI) of Peter the Great St. Petersburg Polytechnic University (SPbPU) analyzed the integrity of an "endoprosthesis-skeleton" system for a case of hip joint revision arthroplasty and assessed the durability of the implanted structure and pelvis bones, as well as the distribution of load when a patient stands on two feet. The work describes the peculiarities of simulation model preparation. Currently, this process takes a long time, but the team is working on a method to reduce the whole calculation to several days.

Other groups tend to entirely ignore pelvic bones in their studies or to consider only their simplified models. However, in this case the researchers paid special attention to detailed description of pelvic bones including their external and porous internal layers. This was done due to the fact that the pelvis is often at risk in its entirety.

"If we consider the work done by us as a virtual test, the article described the load we put on the patient's skeleton and the implant, as if they were tested in reality. Studies like this help reduce the risk of complications in patients with individually designed implants. Hopefully, they would help prioritize prevention over cure," commented Mikhail Zhmaylo, a lead engineer at the Advanced Manufacturing Technologies Center of the National Technology Initiative (NTI) of Peter the Great St. Petersburg Polytechnic University (SPbPU)
Among active participants of the study were graduate students of the "Dynamics and Integrity of Complex Mechanical Systems" program supervised by L.B. Maslov, the Head of the Department of Theoretical and Applied Mechanics of Ivanovo State Energy University, as well as medical practitioners from Vreden Russian Science and Research Institute of Traumatology and Orthopedics.

Peter the Great Saint-Petersburg Polytechnic University

Related Mathematical Model Articles from Brightsurf:

A mathematical model facilitates inventory management in the food supply chain
A research study in the Diverfarming project integrates transport resources and inventory management in a model that seeks economic efficiency and to avoid shortages

Mathematical modelling to prevent fistulas
It is better to invest in measures that make it easier for women to visit a doctor during pregnancy than measures to repair birth injuries.

Predicting heat death in species more reliable with new mathematical model
An international research with the involvement of the Universitat Autònoma de Barcelona (UAB), published in Science, has developed a new dynamic mathematical model which represents a change in paradigm in predicting the probability of heat-related mortality in small species.

Using a Gaussian mathematical model to define eruptive stages of young volcanic rocks
Precise dating of young samples since the Quaternary has been a difficult problem in the study of volcanoes and surface environment.

Moffitt mathematical model predicts patient outcomes to adaptive therapy
In an article published in Nature Communications, Moffitt Cancer Center researchers provide a closer look at a mathematical model and data showing that individual patient alterations in the prostate-specific antigen (PSA) biomarker early in cancer treatment can predict outcomes to later treatment cycles of adaptive therapy.

New mathematical model can more effectively track epidemics
As COVID-19 spreads worldwide, leaders are relying on mathematical models to make public health and economic decisions.

Mathematical model could lead to better treatment for diabetes
MIT researchers have developed a mathematical model that can predict the behavior of glucose-responsive insulin in humans and in rodents.

New mathematical model reveals how major groups arise in evolution
Researchers at Uppsala University and the University of Leeds presents a new mathematical model of patterns of diversity in the fossil record, which offers a solution to Darwin's ''abominable mystery'' and strengthens our understanding of how modern groups originate.

Mathematical model reveals behavior of cellular enzymes
Mathematical modeling helps researchers to understand how enzymes in the body work to ensure normal functioning.

New mathematical model for amyloid formation
Scientists report on a mathematical model for the formation of amyloid fibrils.

Read More: Mathematical Model News and Mathematical Model Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.