Joan and Paul Rubschlager Tribology Laboratory

Artificial joint implants are used to relieve pain and restore function in degenerated joints caused by disease, trauma or genetic condition. The primary function of implants is tribological as the bearing surfaces articulate under load. However, all implantable metal alloys are also susceptible to corrosion to a certain degree, depending on the metallurgical condition, residual or service stresses and surface treatment applied prior to implantation. Corrosion can reinforce tribological damage and vice versa, this is called tribocorrosion. Therefore, artificial joints are susceptible to the usual tribology issues of high friction, wear, corrosion and fatigue and these problems can contribute to failure and revision. The actual corrosion resistance of a material can only be proven by long-term clinical trials, but accelerated laboratory tests can be used to predict certain effects. Understanding the complex physical and chemical interactions between contact surfaces and the surrounding body fluids is now an area of research in artificial joint tribology.

The role of interfacial reactions in the degradation of joint surfaces and junctions by tribocorrosion is studied in the laboratory. We have made substantial contributions to tribocorrosion research and to the understanding of synergies and antagonisms between wear and corrosion in the medical field. We remain active in all aspects of tribocorrosion research. Our activities include the following areas of interest:

• Evaluate the corrosion resistance of various medical alloys by simulating the in vitro inflammatory conditions.
• Address the clinical issue of inflammatory response to wear and corrosion products of metal orthopedic implants by combining in situ culture of cells in a biotribometer.
• Understand and characterize the tribochemical process of fretting corrosion on metals. Investigate the effects of microgrooves on the fretting-corrosion behavior of contemporary hip implants and determine the dominated degradation mechanism.
• Characterize how friction and implant wear are related to lubricant chemistry. Understand the influence of the synovial fluid components (proteins, bovine serum albumin, hyaluronic acid) on the tribological performance of metal alloy, as the electrochemical point of view.
• Analyze surface medical implant by focusing on tribocorrosion products, passive film and carbonaceous ‘tribofilm’.

Polyethylene components are used as liners and bearing surfaces for joint replacements. The Ultra High Molecular Weight Polyethylene (UHMWPE) is the dominant bearing material of choice in Total joint Arthroplasty for its tribological and mechanical properties that can ensure long in vivo service. Cross-linked UHMWPE greatly reduced wear, and particle biocompatibility without causing catastrophic ruptures and tissue reactions.

New and promising materials, like crosslinked and vitamin E charged polyethylenes, are considered safe but innovative and are therefore handled cautiously. Many in vitro tests and several in vivo demonstrations have confirmed the validity of these materials, but it is important to remember that they do not yet have long-term clinical histories. In the Tribology Laboratory, we are investigated the role of debris of crosslinked polyethylene, the quantity and reactivity of which are still to be elucidated and the long-term behavior of cross-linked material. The accurate documentation of the relative wear performance of well-characterized contemporary and historic polyethylene is important both in the projection of the future success of polyethylene-based implant treatment and in the consideration of alternative bearing types. Our interest covers the following topics:

• Evaluate the wear of UHMWPE with joint simulators.
• Develop new methods to measure polymer wear of artificial joints based on the wear and damage score (delamination, cracking, significant deformation).
• Design a custom made joint simulator to investigate the response of knee joints under representative loads.
• Characterize the wear particles in metal-on-polyethylene joints and evaluate the specific immune response, early adverse tissue responses, and genotoxicity.
• Develop a model to consider the individual gait bears on wear rate from gait biomechanics [Collaboration with the Motion Gait Lab].
• Analyze post clinical retrieval analysis of polyethylene tibial components of total knee implants.

Hemiarthroplasty is a procedure to replace degenerative and non healthy articular cartilage by implant material that will articulate against it. It is a surgery less invasive than total joint arthroplasty and preserve the cartilage and bone capital of patients.

The friction and lubrification of hemi implants articulated against articular cartilage is important to be investigated in laboratory in order to extend their lifetime and therefore postpone the implantation of total implant. We have the ability to conduct non stationary mechanical stimulation of live cartilage and complement it with biological analyses to understand the in vitro reaction of cartilage. Our research interests are to:

• Analyze the mechanical and frictional response of different shoulder humeral component materials against the natural glenoid.
• Evaluate the wear and degradation of live cartilage in a tribological interface.
• Quantify biomarkers of the cartilage degradation such as proteoglycans and hydroxyproline.
• Evaluate the viability and metabolic activity of chondrocytes after mechanical stimulation of the cartilage tissue.

Articular or hyaline cartilage is a thin layer of specialized connective tissue that covers the ends of bones. Its primary function is to provide low friction and wear under normal function and to facilitate the transmission of loads to the underlying subchondral bone. When hyaline cartilage begins to degenerate with age, or when it is damaged by injury, the tissue may be overstressed. The injury and resulting loss of function can increase friction, signal further matrix degeneration and initiate osteoarthritis (OA).

Unlike most tissues, articular cartilage is devoid of blood vessels, nerves, or lymphatics. It is composed of a dense extracellular matrix (ECM) with a sparse distribution of highly specialized cells called chondrocytes. The ECM is principally composed of water, collagen, and proteoglycans, with other non-collagenous proteins and glycoproteins present in lesser amounts. Together, these components help to retain/attract water, which is critical to maintain its unique mechanical properties.

From a mechanical point of view, articular cartilage is a composite of materials composed of a fluid phase (mainly water) and a solid phase (ECM). Cartilage is considered a permeable, viscous and elastic material. Due to its elasticity, articular cartilage gives rise to deformations, but always returns to its original shape, and it combines a remarkably long life with low friction. Under dynamic loads, a sort of pumping effect occurs. This leads to an increase in volume and also causes an increase in tension in the collagen fibers, which increases the elasticity of the tissue. Collagen fibers provide good tensile strength. The water-proteoglycan compounds provide compressive strength and elasticity.

The biological and mechanical properties of articular cartilage are very complex and vary from area to area depending on its composition (water concentration, proteoglycan content, collagen fibers orientation). The preservation of articular cartilage is highly dependent on maintaining its organized architecture. A fundamental understanding of articular cartilage mechanics is essential for aiding clinicians in enhancing the longevity of healthy joints and the development of promising treatments for injured joints.

Our group is investigating the unique properties of articular cartilage such as the intrinsic viscoelasticity, the wear resistance and the stiffness. The current interesting research area are focusing on:

• Study the effects of physiological sliding activity (repeated loading and shearing) on the biomechanical and biological homeostasis of articular cartilage.
• Explore the effect of articular cartilage degeneration and property changes on tribological and mechanical function.
• Investigate and assess the potential of early stage treatments for osteoarthritis.
• Perform long-term controlled studies of live cartilage biomechanics and mechanobiology under physiologically consistent sliding conditions.
• Correlate mechanically/enzymatically damaged and healthy cartilage
• Quantify markers characteristic of the biochemical response of cartilage tissue, and observe any structural changes by histological analysis.
• Evaluate the collagen fibers resistance (tensile strength) by tensile test.
• Assess the intrinsic viscoelastic properties and the stress-relaxation response of articular cartilage by nanoindentation.

Biomaterial-associated infections are a result of microorganisms adhering to a medical implant or device. Following adherence of the microorganism to the implant or medical device, biofilm formation can occur. Development of biofilm on an implant surface makes these infections highly resistant to immune host defense and antimicrobials. This resistance makes these biomaterial-associated infections difficult to treat. These types of infections can be challenging to manage and result in:

1. Requirement of additional surgeries and implant removal and replacement;
2. Requirement of prolonged antibiotic treatment;
3. Additional medical complications for the patient; and
4. High medical costs and burden for the healthcare system.

Our team focuses on methods of prevention and treatment of periprosthetic joint infection (PJI), which is infection on and around an artificial implant prosthesis, such as those used in knee or hip replacement surgery. PJI can be a devastating and costly complication of joint replacement surgery and is amongst the leading causes of revised surgery and poor surgical outcomes in orthopedics.

Building on the experience of conducting sterile lab tests and corrosion research, our group investigates the following areas:

• Local delivery of antimicrobials to the implant site, such as through coating the implant with antimicrobial agents. This is in contrast to common systemic oral or intravenous antibiotic utilization, which can result in: i) low bioavailability of antimicrobial drug around the implant and surgical site; and ii) toxic side effects on normal body tissues and organs at high doses.
• Creating microscopic size pockets (nanotubes) on the surface of metal implants to enhance drug loading at the implant site and further optimizing the drug release from these nanotubes.
• Promotion of sustained local bioavailability of antimicrobials on and around the implant through utilization of controlled release materials.
• Utilization of agents targeting prevention of development and disruption of biofilm.
• Preclinical animal models of PJI.

• Dominik Friedrl, Technische Universität Wien, Austria
• Julia Fischer, Germany
• Sofia Gianotti, Politecnico di Milano, Italy
• Francesca De Vecchi, Politecnico di Milano, Italy
• Paul Vanhalst, École des Mines de Saint-Étienne, France
• Saskia Heermant, Technische Universitat Dortmund, Germany
• Cristian Beckmann, Technische Universitat Dortmund, Germany
• Greta Della Fara, Politecnico di Milano, Italy

2016 - 2021

2010 - 2015

2000 - 2010

Staff

Several tribometers are available to evaluate the resistance to wear and corrosion of orthopedic implants. Direct contact with cell cultures is possible thanks to a tribometer housed in an incubator.

• Custom fretting corrosion simulator
• Six station pin-on-disc apparatus (Orthopod, AMTI Inc.)
• Tribocorrosion bioreactor in an incubator 
• Several specifically dedicated hydraulic, pneumatic and electro-mechanic wear testing machines
• Potentiostats for corrosion and electrochemical testing (Gamry Instruments)

Image

Detail of the fretting corrosion chamber.

Image

Tribocorrosion bioreactor.

Image

Six stations pin-on-discs apparatus.

• Two four station knee/ankle motion simulators (EndoLab GmbH)
• A multifunction spine and hip simulator (EndoLab GmbH)
• Four-station hip joint simulator

Image

Image

Image

• Custom cartilage shear simulator
• Custom cartilage damage impactor
• Custom tensile test for cartilage
• Modular compact Rheometer, MCR302e (Anton Paar)

Image

Image

Image

Our group has the infrastructure on site, such as a Biohazard Safety Level 2 room. This room is located on the 7th floor of the Cohn Research Building. The Cohn Research Building is suitable to perform both microbiological and rodent experiments. Our equipment includes but is not limited to the following:

• In Vivo Imaging System (IVIS® Lumina II, Perkin Elmer)
• Spectrophotometer (Nanodrop 2000 UV-Vis spectrophotometer, Thermo Scientific)
• Biosafety cabinet, incubators and centrifuges

• Ti-950 Nanoindenter (Hysitron, Inc.)
• Fourier Transform Infrared (FTIR) spectrometer: Cary 670 (Agilent Technologies)
• Confocal Raman Microscope, LabRAM HR Evolution (Horiba)
• 3D Surface Profiler VK-X3000 series (Keyence)
• Flash 250 SmartScope laser coordinate measuring machine (OGP, Inc.)
• Scanning electron microscope (SEM, JEOL IT500HR, Peabody) equipped with an Energy Dispersive Spectrometer detector (EDS, 65 Ultim Max detector, Aztec 4.1 SP1 software, Oxford Instruments)

Basic laboratory equipment are also available such as ultrasound cleaner, balances, magnifying glasses, pH-meter, centrifuge, water purification, chemical fumehoods, biosafety cabinet, sputter coater for sample preparation, etc.

Image

Ti-950 Nanoindenter

Image

Fourier Transform Infrared (FTIR) spectrometer

Image

Confocal Raman Microscope

Image

3D Surface Profiler

Image

Scanning electron microscope (SEM)

 

1. Impergre A, Trunfio-Sfarghiu A-M, Wimmer MA, Evaluation of articular cartilage wear against pyrolytic carbon in the context of spherical interposition shoulder arthroplasty, Biotribology Journal, Volumes 33–34, 2023, 100237 Link
2. Hamilton JL, Vashi M, Kishen EB, Fogg LF, Wimmer MA, Balk RA. The Association of an Alpha-2 Adrenergic Receptor Agonist and Mortality in Patients with COVID-19. Front. Med. 2022 Jan; 8:797647 Link
3. Queiroz Neto M, Radice S, Hall DJ, Frisch NB, Mathew MT, Fischer A, Jacobs JJ, Pourzal J; Microstructure and electrochemical behavior of contemporary Ti6Al4V implant alloys. Journal of Bio- and Tribo-Corrosion 8, 26 (2022) Link
4. Radice, S., Queiroz Neto, M., Fischer, A., Wimmer, M.A. (2022) Nickel-Free High-Nitrogen Austenitic Steel Outperforms CoCrMo-Alloy regarding Tribocorrosion in Simulated Inflammatory Synovial Fluids. J Orthop Res 40(6):1397-1408
5. Radice, S., Tibbits, G., Lin, A.Y.W., Beyenal, H., Wimmer, M.A. (2022) Interactions between hyaluronic acid and CoCrMo alloy surface in simulated synovial fluids. Biosurface and Biotribology 7(4): 239-250. DOI: 10.1049/bsb2.12027
6. Hamilton, J.L., Vashi, M., Kishen, E.B., Fogg, L.F., Wimmer, M.A., Balk, R.A. (2022) The Association of an Alpha-2 Adrenergic Receptor Agonist and Mortality in Patients with COVID-19. Frontiers in Medicine 8: 797647. 10.3389/fmed.2021.797647
7. Mell, S.P., Wimmer, M.A., Jacobs, J.J., Lundberg, H.J. (2022) Optimal surgical component alignment minimizes TKR wear – An in silico study with nine alignment parameters.  J Mech Behav Biomed Mater 125: 104939. 10.1016/j.jmbbm.2021.104939
8. Thampi, P., Tabbaa, S.M., Silbermans, G., McIlwraith, C.W., Laurent, M.P., Wimmer, M.A., Johnstone, B., Frisbie, D.D. (2022) Articular cartilage surface changes using surface topography in a post-traumatic equine model of osteoarthritis J Orthop Res 40(6):1349-57
9. Cramer, L.A., Wimmer, M.A., Malloy, P., O’Keefe, J.A., Knowlton, C.B., Ferrigno, C. (2022) Validity and Reliability of the Insole3 instrumented shoe insole for ground reaction force measurements during walking and running. Sensors 22(6): 2203.  
10. Chastain, K., Wach, A., Pekmezian, A., Wimmer, M.A., Warren, R., Torzilli, P.A., Chen, T., Maher, S.A. (2022) ACL transection results in a posterior shift and increased velocity of contact on the medial tibial plateau. J Biomech.144:111335
11. Odehnal, L., Ranuša, M., Wimmer, M.A. Vrbka, M., Křupka, I. (2023) Development of lubrication film and influence on friction in a total knee replacement during a gait cycle. Tribol. Int. 178:108073
12. Ganguly, A., Olmanson, B.A., Knowlton, C.B., Wimmer, M.A., Ferrigno, C. (2023) Accuracy of the fully integrated Insole3’s estimates of spatiotemporal parameters during walking. Med Eng & Physics 111:103925
13. Impergre, A., Trunfio-Sfaghiu, A.M., Wimmer, M.A. (2023) Evaluation of articular cartilage wear against pyrolytic carbon in the context of spherical interposition shoulder arthroplasty. Biotribology 33-34:100237

1. S. Maher, A. Pekmezian; A. Wach, T. Chen, K. Chastain, J. Ruzbarsky, M.A. Wimmer, R.F. Warren, P.A. Torzilli. ACL Transection Results In A Posterior Shift And Increased Velocity Of Contact Most Prevalent In The Medial Compartment. Transactions Vol. 47: 67; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
2. C. Yuh, S. Chubinskaya, S. Maher, M.A. Wimmer. Characterization Of Surface Stiffness And Articular Loading-Induced Surface Stiffening In Human Ankle Cartilage. Transactions Vol. 47: 616; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
3. D. Gokul, E. Birch, K. Cheng, M. Mathew, D. Bijukumar, N. Hallab, M.A. Wimmer; J. Jacobs, S. Prasad. Electrochemical Biosensor To Detect Implant Derived Metal Ions In A Mice Model: Development And Validation. Transactions Vol. 47: 777; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
4. A. Impergre, A.M. Sfarghiu, N. Bernoud-Hubac, M.A. Wimmer. Comparative Tribological Study Of Three Biomaterials For Interposition Shoulder Arthroplasty. Transactions Vol. 47: 1276; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
5. S.P. Mell, C. Yuh, T. Nagel, S. Chubinskaya, H.J. Lundberg, M.A. Wimmer. Differences In The Superficial Zone Behavior Between Human And Bovine Cartilage - A Finite Element Analysis. Transactions Vol. 47: 1483; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
6. S. Radice, G. Tibbits, H. Beyenal, M.A. Wimmer. Influence Of Hyaluronic Acid From Synovial Fluid On The Corrosion Of CoCrMo-Alloys. Transactions Vol. 47: 1716; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
7. C. Yuh, S. Liu, D. Hall; A. Hakimiyan, M.A. Wimmer, S. Chubinskaya, R. Pourzal. FTIR-I Chemical Mapping Of Articular Cartilage As A Function Of Tissue Degeneration - A Preliminary Study. Transactions Vol. 47: 2124; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
8. C. Beckmann, S. Heermant, A. Wittrock, A. Fischer, M.A. Wimmer, J. Debus. The Effect Of Machined Surface Topography On Wear Particle Formation In A TiAlV-CoCrMo Taper Contact Model. Transactions Vol. 47: 2146; Annual Meeting of the Orthopaedic Research Society, Tampa, FL, 2022
9. M.A. Wimmer, J. He, N. Shakoor, C. Ferrigno. Gait Training In The Community: Device Development and Proof of Concept Studies. Transactions, International Society for Osteoarthritis, Berlin, Germany, 2022
10. J. He, C. Ferrigno, M.A. Wimmer. Movement Strategies Adopted By Individuals With Knee OA in Response To Pressure-Based Auditory Feedback Gait Retraining. Transactions, International Society for Osteoarthritis, Berlin, Germany, 2022
11. C. Yuh, S.P. Mell, T. Nagel, S. Chubinkaya, H.J. Lundberg, M.A. Wimmer. Comparison of Mechanical Properties in the Superficial Zone of Young Bovine and Mature Human Articular Cartilage. Transactions, International Society for Osteoarthritis, Berlin, Germany, 2022
12. A. Impergre, M.A. Wimmer, A. Sfarghiu, N. Bernoud-Hubac. Tribological Evaluation of a Pyrolytic Carbon Interposition Implant against Live Cartilage in Comparison With Alumina Ceramic and CoCrMo-Alloy. Abstract, International Society for Technology in Arthroplasty, 33rd Annual Congress, Maui, Hawaii, 2022
13. J. Hamilton, A. Markovics, G. Della Fara, A. Impergre, M.A. Wimmer. Use of Electrophoretic Deposition in the Hospital Setting to Coat Medical Implants With Therapeutic Agents to Prevent or Treat Biomaterial Associated Infection. Abstract, International Society for Technology in Arthroplasty, 33rd Annual Congress, Maui, Hawaii, 2022
14. M. A.Wimmer, A. Fischer, P. Telouk. Why Surface Topography of Hip Trunnions Matters Under Fretting Corrosion. Abstract, International Society for Technology in Arthroplasty, 33rd Annual Congress, Maui, Hawaii, 2022
15. G. Della Fara, M.A. Wimmer, J. Hamilton, A. Markovics. Electrophoretic Deposition of Gentamicin and Chitosan into Titanium Nanotubes to Prevent Periprosthetic Joint Infection. Abstract, International Society for Technology in Arthroplasty, 33rd Annual Congress, Maui, Hawaii, 2022