Page 50 - Plastics News April 2017

TECHNOLOGY

Russian Ultra-high-molecular-weight Polyethylene implant

group of Russian scientists have successfully tested natural ability to regenerate, but in case of large defects
A the implants of chancellor bones based on ultra- the natural ability is often insufficient for complete
high-molecular-weight polyethylene (UHMWPE): 100% of bone repair. That's why to repair damaged bone tissue
implanted samples have been successfully grafted. As various types of implants are used. Materials used for
previously reported, NUST MISIS scientists, with the help bone implants must have a number of specific properties:
of colleagues from the Russian Cancer Center, named to be biologically compatible with the host's body,
after N.N. Blokhin, as well as the State Plant for Medical to possess high mechanical roperties, to ensure the
Preparations, learned how to create highly precise complete replacement of the bone loss, and to initiate
simulations of bone tissue structures, which presented the processes of bone tissue regeneration. The ultra-
the opportunity to provide a replacement for bone loss, high-molecular-weight polyethylene is very well suitable
and to initiate the regeneration process while maintaining for the criteria described above. For example, if we talk
the functional capabilities of limbs. An article with the about mechanical properties in terms of strength or self-
research results was published in the "Materials Science weight, the products from UHMWPE have measurements
and Engineering" journal. that exceed steel. That's why potentially the material
suits well for the manufacture of porous implants which
"The research group was able to examine the structural and
mechanical characteristics of the obtained samples both in- have the structure to initiate the porous chancellors
bone tissue processes most accurately. However, the
extremely high molecular weight of polymer doesn't
allow for the use of traditional methods of creating a
porous structure (typically they are created by foaming).
The problem was solved with the help of a solid-phase
mixing method, thermopressure, and rinsing the
materials in subcritical water. With such ingenuity,
a group of Russian scientists solved the problem of
simulating the complex structure of chancellor bones
for the first time in the world, and created the multi-
layer UHMWPE scaffolds with a solid exterior and porous
inner layer. "Our scaffold consists of two layers, which
vitro and in-vivo during the experiment. The breakthrough are connected to each other very firmly. The first layer
fundamental research of NUST MISIS scientists has received is solid - it stimulates the cortical bone to ensure the
practical development thanks to the close cooperation of mechanical strength. The inner layer has pores of a
our University, Russia's leading Cancer Center and the State certain size, that's why it can be colonized by cells from
Plant for Medical Preparations. Particularly, the results of the recipient to accelerate the fusion with surrounding
the in-vivo experiments allowed the team to determine the tissues and to provide a strong fixation of the implant
degree of the inner layer's porosity and pore sizes, in which in the defective area", said Fedor Senatov, Candidate
a strong fixation in bone loss by the ingrowth of connective of Engineering Sciences, head of the project, and
tissue into the implant takes place", commented Alevtina research assistant at the NUST MISIS Center of Composite
Chernikova, Rector of NUST MISIS.The partial replacement Materials.
of bones, destroyed by cancer, injury, or surgery, remains According to the experimentation team, the listed
an important medical problem. In Russia alone over 70,000 features of scaffolds obtained on the basis of UHMWPE
surgeries to restore the integrity of damaged bone tissue will open great prospects for the creation of bioimplants
occur annually. There are hundreds of thousands of such in rehabilitation medicine, a fact already proved by
operations throughout the world. Bone tissue possesses a
scientists in a new series of experiments.

Plastics News | April 2017 50