Page 50 - Plastics News April 2017
P. 50

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
   45   46   47   48   49   50   51   52   53   54   55