Parx technology in polymer parts of hip and knee joints protected by granted EU patent.

Parx Plastics NV (Euronext: MLPRX) is pleased to report that our EU patent application for the use of the company’s technologies in polymer parts of orthopaedic implants (e.g. hip and knee joints) has been granted.

Earlier this year the patent was already granted in the territory of Italy and the extension into the rest of the EU is now successfully completed. The patent will provide Parx’ biocompatible technologies with protection specifically in the orthopaedic field, further strengthening the company’s patent portfolio. UHMWPE components are used in total endoprosthetic joints, for example in endoprothesis of the hip, knee, shoulder, ankle, elbow and vertebral column. 

Prof. Luigi Costa, PhD– researcher and specialist in Vitamin E-blended UHMWPE biomaterials connected to the Department of Molecular Biotechnology and Health Sciences, Molecular Imaging Center of the University of Torino, Italy: 

“The Parx Plastics technology improving the resistance to adhesion of bacterial biofilms to the surface of orthopedic prostheses parts made from UHWMPE with Vitamin E, represents a further step forward in better controlling the risks of infection.”  


Prosthetic Joint Infection (PJI) is one of the most serious complications after joint implant arthroplasty. This issue is not only a challenge to the orthopedic surgeon but also to the patient and their families in terms of the physical and psychological impacts that are normally associated with this problem. It not only affects their quality of life but also their ability to return to their daily routine. Another important aspect of prosthetic infection is its serious economic impact. The cost of curing this type of infection is on average EURO 62,500 per patient depending on the number of surgeries, complications and antibiotic treatments the patient requires. In general, when the prosthesis becomes infected, three to four times as many resources are required in comparison to a primary knee arthroplasty.

Recent studies indicate that:

  • PJI is the first reason for failure for knee replacement and the third reason for hip replacement in the United States;

  • In Europe, with slight differences between countries, PJI is among the top three reasons leading to revision surgery.

Studies show that prosthesis infections are actually biofilm-correlated infections that are highly resistant to antibiotic treatment and the immune responses of the host. The main characteristic of prosthetic infections is the formation of a biofilm on the surface of the implants.

Prof. Dr. Stefano Zanasi–  Renowned Orthopedic surgeon, traumatologist and specialist in regenerative surgery and biotechnology practicing in London, UK and Bologna Italy, performing around 950 operations per year: 

"The relevance of the nosocomial infections in orthopedic applications is a problem we have to solve as antibiotic resistance is on the raise. With the Parx Plastics technology, today we can look at it with different eyes”


For the verification of the characteristics of the technology developed by Parx Plastics and its functionality in UHMWPE with Vitamin E, the company cooperated with different universities and an accredited laboratory. The studies performed have determined an important reduction in Gram-positive and Gram-negative bacteria.

The microbial load detected on the surface of samples integrated with the Parx Plastics technologies, after different times of contact, is quantitatively less than the value obtained on normal samples without this technology, obtaining percentage of inhibition of 99.99% after 48 hours.

The strains tested were:

  • Staphylococcus epidermidis ATCC 12228;

  • Staphylococcus aureus MRSA ATCC 25923;

  • Enterococcus faecalis ATCC 29212

  • Pseudomonas aeruginosa ATCC 9027

Other in-vivo studies have shown that the Parx Plastics technologies also effectively prevent biofilm adhesion on the surface. This prevents the build-up of biofilm and it consequently prevents bacteria assembling within this biofilm. This is a great value for medical implants as the relapse rate that is observed in orthopedic implant infections, even after very prolonged treatment is due to the formation of biofilm: the bacteria assemble themselves within this biofilm in different strata as each has distinct metabolic activities. At the same time, these bacteria secrete an extracellular polymeric substance that helps the bacteria that are located in the deepest strata of the biofilm to survive in reduced metabolic conditions with little available nutrients. These are the bacteria that have the highest resistance to antibiotics, as opposed to those bacteria that are located on the biofilm's surface. When the biofilm has formed, there is no possibility for the surgeon to leave the implant as this must be removed and substituted by an antibiotated spacer to avoid severe complications up to septicaemia and death.



Ultra-high-molecular-weight polyethylene is a subset of the thermoplastic polyethylene. It has extremely long chains and these serve to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material with the highest impact strength of any thermoplastic presently made. It is highly resistant to abrasion, in some forms 15 times more resistant to abrasion than carbon steel, and therefor the material has a clinical history as a biomaterial for use in hip, knee and spine implants. 

In the study leading to the patent application the UHMWPE with Vitamin E samples (both with and without the technology) were characterized by means of differential scanning calorimetry (DSC), Fourier Transform InfraRed (FTIR) Spectroscopy and small-punch testing (according to the guidelines established in ASTM F2183). The physical-mechanical characteristics of the material are only slightly modified with correlation to the percentages of added technology, however still largely within the limits for the acceptability of the material for the realization of joint prostheses.


Large players dominate the global orthopedic market, estimated at $34 billion. A group of 5 in the US controls 65% of the orthopedic implants market. For knee and hip replacements, Zimmer Biomet, which generates $2.3 billion with this activity, is in a leadership position with 35% of the market. In 2016, Zimmer bought Biomet for $14 billion. DePuy Synthes, a J&J subsidiary, has 21% of the market and ranks second. DePuy / J&J bought Synthes in 2012 for $21.3 billion. These two operations have further accentuated the concentration of the sector. 

This situation is reducing the number of potential customers for Parx Plastics in the field of orthopedics. However, each and every player in this market has the same top-priority: reducing infection risks. With the rise of antibiotic resistance over the past years this has become the key topic for these players and Parx Plastics feels it has a key technology in hands to address this. 

Parx Plastics realizes that there are still plenty of milestones to be reached prior to be able to commercialize this application. For this the company hopes to team up with a strong knowledgeable player taking on this co-development and together overthrow this pressing matter in the orthopedic field. In the meantime more tests in the healthcare field are performed and other medical applications and advantages of the technology in this field are studied. 

Parx Plastics