The new frontier of printed robots: bones, ligaments, and tendons

3D printing is rapidly advancing, with a significant expansion in the range of available materials. Previously confined to fast-curing polymers, the technology can now accommodate slow-curing polymers, offering distinct advantages such as enhanced elastic properties, durability, and robustness.

This breakthrough is attributed to a novel technology developed by researchers at ETH Zurich in collaboration with a US start-up. Consequently, researchers can now employ a variety of high-quality materials to 3D print intricate and more durable robots in a single process. The technology also facilitates the seamless combination of soft, elastic, and rigid materials, enabling the creation of delicate structures and parts with desired cavities.

A notable application of this innovation is demonstrated by ETH Zurich researchers who have successfully 3D printed a robotic hand with integrated bones, ligaments, and tendons made from different polymers in a single operation. This achievement was made possible by utilizing slow-curing thiolene polymers, known for their excellent elastic properties and rapid return to their original state after bending.

Thomas Buchner, a doctoral student in the group of ETH Zurich robotics professor Robert Katzschmann, highlights the significance of these polymers: “We’re now using slow-curing thiolene polymers. These have very good elastic properties and return to their original state much faster after bending than polyacrylates.” This makes thiolene polymers ideal for producing the elastic ligaments of the robotic hand.

The flexibility of thiolenes in terms of stiffness allows for precise tuning, meeting the specific requirements of soft robots. Katzschmann explains the advantages of soft robots, emphasizing their reduced risk of injury when interacting with humans and suitability for handling fragile goods, making them superior to conventional metal robots.

Traditional 3D printing methods involved scraping off surface irregularities after each curing step, a process compatible only with fast-curing polyacrylates. To accommodate slow-curing polymers like thiolenes and epoxies, the researchers incorporated a 3D laser scanner into the printing process. This scanner immediately checks each printed layer for surface irregularities, enabling a feedback mechanism to make real-time adjustments to the amount of material printed in subsequent layers, without the need for smoothing uneven layers.

The new printing technology was developed by MIT spin-off, Inkbit, in collaboration with ETH Zurich researchers who optimized the technology for use with slow-curing polymers. Their joint efforts have been published in the journal Nature. Moving forward, Katzschmann’s group at ETH Zurich plans to explore further possibilities using this technology, developing more sophisticated structures and additional applications. Meanwhile, Inkbit intends to offer a 3D printing service to customers and market the new printers incorporating this advanced technology.



  • Buchner TJK, Rogler S, Weirich S, Armati Y, Cangan BG, Ramos J, Twiddy S, Marini D, Weber A, Chen D, Ellson G, Jacob J, Zengerle W, Katalichenko D, Keny C, Matusik W, Katzschmann RK: Vision-​Controlled Jetting for Composite Systems and Robots, Nature, 15. November 2023, doi: external page10.1038/s41586-​023-06684-3call_m


This article was written by Elisa Bissacco as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

She is studying a PhD in Tribological Characteristics of Nanofibrous Electrospun Materials at ETH Zurich.

Cartilage 101: How your joints prevent you (almost always) from feeling pain

Articular cartilage, found within a flexible joint capsule, contains synovial fluid and the meniscus. The surface prevents stick-and-slip contact under body weight sustaining or rapid sliding, for example, at jogging or playing tennis. Weight-bearing cartilage exhibits low friction coefficients due to a biphasic structure. This works as a sponge, comprising a fluid phase and a solid, porous extracellular matrix (ECM). Regenerating cartilage is difficult because of its shape, chemical composition, and demanding cells. Recent approaches involve using stem cells for regeneration, but the intricate link between cell characteristics and tissue function must be considered.

Moving on to lubricants, substances like hyaluronic acid and lipids contribute to reducing joint friction. Hyaluronic acid, a common ingredient in cosmetics, exhibits shear-thinning properties in synovial fluid, lowering friction. Remembering a post from Mahdieh, shear-thinning materials have lower viscosity at speeds. This is what makes nail polish and paints spread but stick to the surface when to dry. Lubricin, a glycoprotein, and aggrecan, a proteoglycan, further contribute to boundary lubrication, maintaining a hydrated environment. These lubricants prevent solid-solid contact against cartilage at slow movement or high loads. However, when more lubrication is demanded, cartilage pores expel some of their moisture and lubricants to the joint space. [1–3]


[1]        E.D. Bonnevie, L.J. Bonassar, A Century of Cartilage Tribology Research Is Informing Lubrication Therapies, Journal of Biomechanical Engineering. 142 (2020) 031004.

[2]        J. Liao, X. Liu, S. Miramini, L. Zhang, Influences of variability and uncertainty in vertical and horizontal surface roughness on articular cartilage lubrication, Computers in Biology and Medicine. 148 (2022) 105904.

[3]        C.W. McCUTCHEN, Mechanism of Animal Joints: Sponge-hydrostatic and Weeping Bearings, Nature. 184 (1959) 1284–1285.

This article was written by André Plath  as part of a series articles curated by BioTrib’s Early Stage Researchers.

André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

Book synopsis: The culture map by Erin Meyer

Header Image: Globe (CC BY 2.0 license).

Do you prefer direct criticism or that people adopt a three-positives for one negative approach? Do you communicate in a “mean what you say” or “read the air” manner? In your job are fixed consensual decisions or flexible top-down approaches preferred?

In international environments, these are frequent questions that change according to the culture and background of teams across the world. Erin Meyer, professor at INSEAD (Institute National d’Administration et des Affaires) in Paris, talks about her experiences coaching industries around the globe. In her book, she lists eight common cultural differences (communication, negative feedback, persuasion, leadership, decision-making, trust, conflict, and scheduling) around different cultures on all continents. She also shares practical examples of how they create conflict, miscommunication, and different perceptions of people with different world views. Finally, she gives practical tips on how to navigate them better and harvest the potential of multiculturality.

Cultural fluency might not eliminate misunderstandings, but can definitely minimize them and foster collaboration in international teams.

This article was written by André Plath  as part of a series articles curated by BioTrib’s Early Stage Researchers.

André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

The life of a researcher in Latin America

Header Image: Latin American Map (CC BY-SA 4.0)

As a Latin American early career researcher, my routine was very different than at Biotrib. I used to juggle two jobs with my time in the lab and my personal life. I and my colleagues funded our research with our jobs. Sometimes we even acquired laboratory consumables. Today I live in a much different reality. I would like to discuss things that motivated me to seek a Ph.D. abroad and maybe cast a light on how to improve things in my home country, Brazil.

Ciocca and Delgado in “The Reality of Research in Latin America: An Insider Perspective” discuss key aspects of research in Latin American countries. They list economic factors (low or completely lacking salaries, low research budgets), political instability, and limited career opportunities are identified as primary drivers prompting skilled professionals to seek employment abroad. Their review emphasizes how these factors collectively contribute to a significant loss of human capital, impacting the economic and social development of the Latin American nations. Furthermore, the article highlights the role of education systems and the lack of research infrastructure in Latin American countries as additional contributors to the brain drain.

The consequences of brain drain are a “brain waste” scenario, where skilled individuals find themselves underemployed or unable to utilize their full potential in host countries. This creates a shortage of qualified personnel due to emigration. This also reflects on the quality and recognition of research: only scientists from Argentina, Mexico, Chile, and Guatemala were awarded Nobel Prizes, for example. I would love to go back and contribute to the local development of my country. With the Ph.D. established partnerships and resources, I believe I can contribute to a technology exchange.


Ciocca, D. R., & Delgado, G. (2017). The reality of scientific research in Latin America; an insider’s perspective. In Cell Stress and Chaperones (Vol. 22, Issue 6, pp. 847–852). Springer Science and Business Media LLC.


This article was written by André Plath and Giulio Cavaliere as part of a series articles curated by BioTrib’s Early Stage Researchers.

André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

From Waste to Wisdom: Navigating Plastic Reduction in the Lab

How many times have we asked ourselves in the lab: how much plastic do we use? Significant groundwork for societal advancement is laid by laboratory research. Meanwhile, it’s believed that 2% of the world’s plastic waste comes from laboratory operations, which contributes to their environmental footprint [1].

So, “What can you do to make your lab greener?”. This is the title of an article [2] that discusses the environmental footprint of research labs and the increasing awareness among scientists about their waste production. They do not provide specific details on reducing plastic waste in labs, but they highlight the importance of small changes and individual efforts in reducing energy usage and promoting sustainability in research labs. Obviously, not all of these efforts will be easily transferred to individual labs, but small changes can have a significant impact on the majority of normal bench science.

Without going into too much detail, what are the small steps we could take to the reduction of plastic consumption in the laboratory?

-Start the discussion: encouraging researchers to be mindful of their plastic consumption and promoting awareness about the environmental impact of plastic waste can lead to more conscious choices.
-Reuse and recycle: using reusable or sustainable alternatives, such as glassware instead of plastic, can significantly reduce plastic waste.
-Shop smart: buying only the quantity you need and choosing suppliers with less and reusable packaging can reduce the amount of packing waste and delivery carbon footprint.
-Promote responsible waste management and educate lab members: implementing recycling programs and proper waste management practices can help reduce plastic waste in research labs [2].
-Sharing: sharing equipment among labs can minimize the need for single-use plastic items [2].

What do you think? Do you have any other solutions or ideas? Let’s discuss it 😉

[1] Urbina 2015 (Labs should cut plastic waste too | Nature)
[2] Madhusoodanan 2020 (d41586-020-01368-8.pdf (


This article was written by Alessio Amicone as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Alessio is investigating the Elucidation of Friction-Induced Failure Mechanisms in Fibrous Collagenous Tissues at ETH Zürich, Switzerland.

Biomechanical Testing of Medical Devices: Translating Lab Results to Real-World Applications

When engaging in discussions about my research, particularly with individuals outside of academia, often within my community, I frequently encounter a common question: “What is your involvement with artificial hip joints? Are you a doctor?” In response, I find myself explaining the various phases of developing load-bearing implants and clarifying the role I play as a mechanical research engineer. In this article, I aim to elucidate the developmental stages of implants, spanning from the laboratory to clinical application, and emphasize the valuable contributions made by engineers like myself.

Biomedical implants undergo several essential stages before being suitable for implantation in the human body. These stages encompass material development and characterization, biocompatibility testing, biomechanical testing for load-bearing implants, in vivo implantation, and ultimately human trials. Throughout the initial three stages, engineers play a significant role, with a particular emphasis on biomechanical testing (Stage I-III in the figure). This is because before biomedical devices make their way into clinics and hospitals, rigorous testing is essential to ensure their safety, efficacy, and compatibility with real-world conditions. This is where biomechanical testing comes into play, serving as a bridge between laboratory experiments and real-world applications.

Biomechanical testing is a multidisciplinary approach that evaluates the mechanical behaviour and performance of medical devices in simulated physiological environments. It involves a combination of engineering principles, biology, and clinical knowledge to mimic the conditions the device will face within the human body. This testing is crucial to identify potential issues, assess the device’s functionality, and refine its design before it reaches the patient termed as preclinical testing. Such as Implants with moving parts (hip or knee prostheses) undergo wear testing to assess the materials’ performance and any potential debris generated by friction. This is crucial to avoid complications like inflammation or tissue damage. The tests are guided by several international standards. ISO 14242 primarily focuses on wear testing in a laboratory setting, it emphasizes the importance of ensuring that wear testing conditions are relevant to the clinical conditions experienced by patients with hip implants. Whereas ISO 7206 provides guidelines for the development, testing, and performance evaluation of hip joint implants to ensure their safety and efficacy.

Biomechanical testing is carried out using a range of mechanical simulators, including pin-on-plate tribometers, hip and knee simulators, and more. As researchers, we are deeply involved in these efforts. Furthermore, our team at the University of Leeds actively collaborates with patients and surgeons at Leeds Teaching Hospital, effectively bridging the gap between academia and the medical sector.

For further insights into the phases of implant development, I recommend reviewing the following article.

Hamadouche, Moussa, et al. “Alumina-on-alumina articulation in total hip arthroplasty: From bench-side to bedside.” Seminars in Arthroplasty. Vol. 17. No. 3-4. WB Saunders, 2006.


This article was written by MM Raihan as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Raihan is researching In-situ Measurement of Nano-scale Wear Utilising Advanced Sensors at the University of Leeds, UK.

The Crucial Role of Lubrication in Joint Replacement Design

Joint replacement surgeries have revolutionized the field of orthopedics, providing relief and improved mobility to many patients suffering from joint diseases such as osteoarthritis and rheumatoid arthritis. Nowadays, due to an aging population and a desire for an active lifestyle, the number of these operations has considerably increased [1, 2]. Studies indicated that wear and debris are the main problems leading to the failure of joint implants, and lubrication can considerably decline these acute complications [3, 4]. It is noticeable that the existence of lubrication is evident in healthy synovial joints such as the hip and knee joints, where it relies on the presence of synovial fluid (Figure 1).  Thus, I firmly believe that lubrication is crucial in designing joint replacements because it ensures the durability and functionality of joint implants while reducing complications and patient pain. To end this, the main purpose of my PhD project is to design a hip prosthesis that can replicate the natural lubrication found in synovial joints.

Figure 1) Anatomy of a healthy a) hip joint b) knee joint [5]
The significance of lubrication in joint replacement design is explained in detail as follows. One of the main functions of lubrication in joint prostheses is to reduce friction between the different components. As these joint replacements imitate the motion of the natural joints, they experience numerous mechanical stresses daily. Inadequate lubrication can lead to generating friction between the bearing surfaces and accelerating wear which can result in premature implant failure. The lubrication film functions as a protective barrier, avoiding direct contact between the bearing surfaces and thereby minimizing friction and wear. Furthermore, complications of friction between different components of the prostheses include implant loosening, osteolysis, and debris discharged into the joint space. These issues may cause discomfort, instability, and eventually implant failure as well as revision surgery. Effective lubrication prevents these issues by declining friction and wear, which in turn significantly increases the lifespan of joint replacements. Additionally, lubrication is crucial not only for the mechanical performance of the implant but also for the patient’s comfort and functionality. Appropriate lubrication reduces the feeling of joint stiffness and soreness to a great extent, significantly restores joint function, and allows patients to have a more active life post-surgery. Enhanced patients’ quality of life is a contributing factor in the success of joint replacements.

In conclusion, the significance of lubrication in orthopedic implant design cannot be overstated. It can noticeably contribute to the accomplishment of life-altering joint replacement surgeries as lubrication substantially enhances the durability and functionality of prostheses by decreasing friction, minimizing complications, and increasing patient comfort.


[1] A. Ford, Z. Hua, S. J. Ferguson, L. A. Pruitt, and L. Gao, “A 3D-transient elastohydrodynamic lubrication hip implant model to compare ultra high molecular weight polyethylene with more compliant polycarbonate polyurethane acetabular cups,” Journal of the Mechanical Behavior of Biomedical Materials, vol. 119, p. 104472, 2021.

[2] L. Wang, G. Isaac, R. Wilcox, A. Jones, and J. Thompson, “Finite element analysis of polyethylene wear in total hip replacement: A literature review,” Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, vol. 233, no. 11, pp. 1067-1088, 2019.

[3] L. Mattei, F. Di Puccio, B. Piccigallo, and E. Ciulli, “Lubrication and wear modelling of artificial hip joints: A review,” Tribology International, vol. 44, no. 5, pp. 532-549, 2011.

[4] L. Gao, X. Lu, X. Zhang, Q. Meng, and Z. Jin, “Lubrication Modelling of Artificial Joint Replacements: Current Status and Future Challenges,” Lubricants, vol. 10, no. 10, p. 238, 2022.



This article was written by Mahdieh Mosayebias part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Mahdieh is researching the Design of Self Lubricating Prothesis at ETH Zurich, Switzerland.

Hoda Gendya’s Victory at the NIHR Surgical MedTech Co-Operative Poster Competition

We are thrilled to announce that undergraduate student Hoda Gendya has been awarded the top honor at the NIHR Surgical MedTech Co-Operative poster competition, hosted by the IMechE in London. Her exceptional research poster titled “A Novel Method for the Synthesis and Fabrication of 3D Printed Chitosan Based Hydrogels” stood out amongst a field of formidable contenders, earning her a well-deserved cash prize.

Hoda’s poster dives deep into the innovative realm of 3D printing using chitosan-based hydrogels. Chitosan, derived from the exoskeletons of crustaceans, possesses intrinsic properties that make it highly sought-after in biomedical applications. It is biocompatible, biodegradable, and has unique abilities to respond to external stimuli like pH, temperature, and UV light.

Her research specifically highlights the formulation and 3D printing of these hydrogels using a method that is efficient and cost-effective. By incorporating polyethylene fibers into the mix, Hoda was able to reinforce the hydrogel structure, enhance its mechanical properties, and ensure a smoother print quality.

But the applications of this work go beyond just fabrication. The hydrogels’ swelling behavior, as indicated in her findings, suggests promising potential in drug delivery systems. Their compressive strength, on the other hand, points to their suitability for cartilage replacement or even tissue engineering.

Under the guidance of Professor Michael Bryant and mentored by PhD student Robert Elkington, Hoda’s research has blazed a trail for future work in the domain of medical engineering. Her findings, especially in the realm of biotribology, are poised to transform the way we perceive joint replacement materials and their capacity to mimic and support natural cartilage function.

We wish to extend our heartiest congratulations to Hoda Gendya for her monumental achievement. Her dedication, meticulous research, and innovative spirit are an inspiration to budding researchers and seasoned professionals alike. We eagerly anticipate the continued contributions she will make to the realm of medical engineering and beyond.

Well done, Hoda!

Outreach program: Scifest 2023

SciFest is a science festival organized by Uppsala University (UU) and Swedish University of Agricultural Sciences (SLU). The festival is filled with workshops, shows and scientific talks designed to inspire the love of science in young minds. The exhibitors include many departments from UU and SLU, companies, and the municipality. Although many of the exhibitions are designed for young students, SciFest welcomes all curious people, setting up an environment where anyone can get a glimpse into the world of science and research in a wide range of fields.

This year, SciFest took place over three days from September 21st to September 23rd. The first two days were dedicated to school students and their teachers. The festival was open to the general public on the third and final day, ensuring that the wider community could also partake in this experience.

As part of their commitment to public outreach and science communication, four BioTrib ESRs participated in SciFest. The booth featured by the BioTrib ESRs was titled ‘Unveiling the Power of 3D Printing in Medicine’. The booth displayed models of organs and body parts produced using various 3D printing techniques. This includes spine and heart models and prostheses such as dental and hip prostheses. The booth also had a 3D-printer (fused filament fabrication) running non-stop to print a model of human skull for the audience to see. These representations showcased the potential of 3D printing in biomedical applications. Furthermore, the ESRs also prepared cells and a microscope so the audience can see the appearance of the building blocks of life in person.

Throughout the event, the BioTrib ESRs engaged the public with a resounding passion for their research. Their involvement was not only to showcase their work, but also to share their own journeys into the world of research and to answer any questions about the possibilities of scientific careers. This event has undoubtedly given the BioTrib ESRs a chance to inspire future scientific minds.

For further details on the event, please check their website at

Credit to BioTrib Early Stage Researcher’s Giulio Cavaliere, Marie Moulin, Niccoló de Berardinis, and Vidhiaza Leviandhika!

What should be accepted in biomedical practice and research? New and old ethical dilemmas

Should young blood transfusions be allowed in rejuvenation processes? Is it ethical to pay for these transfusions? Should donors be remunerated? Is it ethical to increase the human life span by getting blood from younger donors transfused to older people? These questions stir up strong emotions in most of us. They represent not only ethical dilemmas but are within the boundaries of our scientific and philosophic understanding.

The history of human blood transfusions is odd. From early attempts with animals and bleeding to cure a series of ailments to our understanding of blood types, blood has stirred a lot of controversy. Bill Schutt brilliantly discusses some of these interesting stories in the lecture: What goes in: The strange story of blood transfusions available on Youtube.

With the new research on young blood transfusions to young patients (parabiosis), several effects were observed such as the reversion of aging-related degenerative diseases (1) and the increase of mice life span (2). This motivated the development of startups that quickly received huge sums of private funding (1). Since then, regulatory agencies such as the FDA have issued notes about the topic (3). In their note from 2019, FDA discusses: “Today, we’re alerting consumers and health care providers that treatments using plasma from young donors have not gone through the rigorous testing that the FDA normally requires in order to confirm the therapeutic benefit of a product and to ensure its safety. As a result, the reported uses of these products should not be assumed to be safe or effective.“ However, researchers are careful about these findings and recommend caution. The factors that play in these transfusions in animal studies are not clearly understood by the scientific community (3). Therefore, they cannot be translated into the complexity of humans. Given our little understanding, the regulation of research and the market of parabiosis is paramount. We should think together as a society on answers to the questions asked opening this short communication.

Read more:

(1)CORBYN, Zoe. Could young blood stop us from getting old? The Guardian: 2 Feb. 2020. Available at:

(2)ZIMMER, Carl. Blood of young mice extends the life in the old? The New York Times, Jul. 2023. Available at:,showed%20signs%20of%20accelerated%20aging

(3) GOTTLIEB, Scott. Statement from FDA Commissioner Scott Gottlieb, M.D., and Director of FDA’s Center for Biologics Evaluation and Research Peter Marks, M.D., Ph.D., cautioning consumers against receiving young donor plasma infusions that are promoted as unproven treatment for varying conditions. Available at:

SCHUTT, Bill. What goes in the strange story of blood transfusions? Available at:


This article was written by André Plath  as part of a series articles curated by BioTrib’s Early Stage Researchers.

André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

What is matrix-assisted chondrocyte implantation (MACI)?

Header Image: Two-step Matrix Assisted Chondrocyte Implantation

Osteoarthritis is a condition associated with discomfort and significant challenges for the affected individuals. Pain management often involves the utilization of pain-relieving medications that can potentially lead to dependency [1]. Joint function restoration is achieved through the implementation of metal implants, although their durability is limited. Consequently, a secondary surgical procedure might be necessary as the patient ages. The use of these implants also presents additional complications such as inflammation induced by the gradual wear of microscopic components [2].

In response to these issues, chondrocyte implantation was introduced during the 1980s in Sweden. This medical procedure involves the extraction of cartilage or stem cells from the patient, which are then propagated within a supportive scaffold material (matrix) [3]. Subsequently, these multiplied cells are reintroduced into the patient’s body (Figure), contributing to tissue regeneration (two steps). An alternative method involves microfracture and scaffold implantation in one step, allowing cells to populate the material and facilitate cartilage reconstruction [3]. These newer techniques exhibit improved rates of success when compared to external cartilage growth [4].

However, a key challenge emerges when cartilage cells transform, losing their original properties. As a result, the newly generated tissue tends to become less lubricant. This phenomenon arises due to the limitations of the scaffold in replicating the intricate conditions found within living tissue [5]. The implications of this could involve detachment or accelerated wear of the implant, necessitating further surgical intervention, and potentially even the use of metal implants. Current materials utilized include foam structures derived from pork collagen or laser-etched plastics [6,7]. Nonetheless, promising advancements are being explored in the experimental phase, involving bio-based materials produced through techniques like 3D printing and fiber integration. One notable application of these innovations is the potential to postpone the need for a prosthesis, thereby offering a beneficial outcome, particularly for younger patients.



[1]          L.M. Billesberger, K.M. Fisher, Y.J. Qadri, R.L. Boortz-Marx, Procedural Treatments for Knee Osteoarthritis: A Review of Current Injectable Therapies, Pain Res. Manag. 2020 (2020) 1–11.

[2]          O. Hussain, B. Ahmad, S. Saleem, Biomaterials for Artificial Knee Joint Replacement: A Review, Int. J. Mater. Eng. Innov. 14 (2023) 1.

[3]          G. Filardo, E. Kon, A. Roffi, A. Di Martino, M. Marcacci, Scaffold-Based Repair for Cartilage Healing: A Systematic Review and Technical Note, Arthrosc. J. Arthrosc. Relat. Surg. 29 (2013) 174–186.

[4]          M.R. Steinwachs, J. Gille, M. Volz, S. Anders, R. Jakob, L. De Girolamo, P. Volpi, A. Schiavone-Panni, S. Scheffler, E. Reiss, U. Wittmann, Systematic Review and Meta-Analysis of the Clinical Evidence on the Use of Autologous Matrix-Induced Chondrogenesis in the Knee, CARTILAGE. 13 (2021) 42S-56S.

[5]          A.R. Armiento, M.J. Stoddart, M. Alini, D. Eglin, Biomaterials for articular cartilage tissue engineering: Learning from biology, Acta Biomater. 65 (2018) 1–20.

[6]          J.L. Carey, A.E. Remmers, D.C. Flanigan, Use of MACI (Autologous Cultured Chondrocytes on Porcine Collagen Membrane) in the United States: Preliminary Experience, Orthop. J. Sports Med. 8 (2020) 232596712094181.

[7]          V.M. Mehta, S. Mehta, S. Santoro, R. Shriver, C. Mandala, C. Weess, Short term clinical outcomes of a Prochondrix® thin laser-etched osteochondral allograft for the treatment of articular cartilage defects in the knee, J. Orthop. Surg. 30 (2022) 102255362211417.


This article was written by André Plath and Giulio Cavaliere as part of a series articles curated by BioTrib’s Early Stage Researchers.

André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.

The Evolution of Total Knee Replacement: Tracing the Path of Surgical Advancement

Total Knee Replacement (TKR), also known as total knee arthroplasty (TKA), stands as one of the most remarkable achievements in modern medicine, revolutionizing the lives of countless individuals suffering from debilitating knee conditions. The history of total knee replacement is a journey through decades of innovation, surgical mastery, and persistent dedication to enhancing patients’ quality of life.

Early Endeavors and Conceptualization (19th to Early 20th Century)

The inception of total knee replacement can be traced back to the late 19th century when surgeons began to experiment with joint replacement procedures. However, it wasn’t until the early 20th century that the concept of total knee replacement started to take shape. One of the earliest documented efforts was by Themistocles Gluck in 1891, who proposed the idea of using ivory to replace a knee joint. This concept laid the foundation for future developments in knee replacement surgery.

Hinged Implants and Early Innovations (1950s – 1970s)

The mid-20th century witnessed significant advancements in orthopedic surgery, encouraging the development of hinged knee implants. In the 1950s, Dr. Leslie Gordon Percival Shiers successfully implanted a hinged knee joint, effectively treating severe arthritis. This marked a turning point, as surgeons began to explore alternatives to total knee fusion.

In the 1970s, the era of modern total knee replacement truly began. Dr. John Insall, along with his colleagues, developed the Insall-Burstein knee prosthesis, which aimed to reproduce natural knee kinematics. This design laid the groundwork for future innovations in implant design, implant fixation techniques, and surgical approaches.

Advancements in Implant Design and Surgical Techniques (1980s – 1990s)

The 1980s and 1990s brought remarkable progress in total knee replacement. Implant materials evolved, with surgeons experimenting with various combinations of metals and plastics to enhance durability and minimize wear. This period also saw the rise of minimally invasive surgical techniques, which aimed to reduce trauma, blood loss, and recovery time for patients.

Computer-Assisted Surgery and Personalized Implants (2000s – Present)

The turn of the millennium marked a shift toward computer-assisted surgeries and personalized implants. Computer navigation systems were introduced, enabling surgeons to achieve higher levels of accuracy in implant placement. Patient-specific implants, utilizing advanced imaging and 3D printing technologies, gained prominence, allowing for a more tailored approach to each patient’s anatomy.

Current Trends and Future Prospects

Total knee replacement continues to evolve. Researchers are exploring innovative materials, such as bioactive coatings and advanced polymers, to enhance implant longevity. Robotic-assisted surgeries have emerged, offering even greater precision and potentially improved outcomes.

Furthermore, the focus has extended beyond the surgical procedure itself to post-operative rehabilitation and patient education. Multidisciplinary approaches now involve physical therapists, pain management specialists, and psychologists, ensuring patients recover not only physically but also mentally.

In conclusion, the history of total knee replacement mirrors the remarkable progress of medical science and technology. From early conceptualizations to today’s state-of-the-art procedures, the journey has been marked by innovative ideas, persistent experimentation, and a commitment to enhancing patients’ lives. As we move forward, it’s likely that total knee replacement will continue to push the boundaries of what’s possible, providing renewed hope and mobility to individuals around the world.



  • Ranawat, History of total knee replacement. J South Orthop Assoc. 2002 Winter;11(4):218-26. PMID: 12597066.
  • Gunston, FH. Polycentric knee arthroplasty. Prosthetic simulation of normal knee movement: interim report.Clin Orthop Relat Res, 1973(94): p. 128-35.


This article was written by Elisa Bissacco as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

She is studying a PhD in Tribological Characteristics of Nanofibrous Electrospun Materials at ETH Zurich.

An Investigative Analysis of the Human Knee in Comparison to Six Different Animal Species from an Anatomical Perspective

Benedikt Proffen et al. in the article titled “A Comparative Anatomical Study of the Human Knee and Six Animal Species” discuss the need for effective treatments for intra-articular knee injuries and the importance of using large animal models for translational research in knee surgery. The study aims to systematically and quantitatively compare the anatomy of the intra-articular structures of the human knee with those of six animal species (cow, sheep, goat, dog, pig, and rabbit) to determine best-practice models for experimental knee surgery.

The study involved harvesting knees from the mentioned animal species and human cadavers. The knees were thawed, and passive range of motion was measured.

Dissections were performed to reveal the anatomy of the knee structures, including cruciate ligaments (ACL and PCL), menisci (medial and lateral), tibial plateau width, and intercondylar notch width.

Measurements were taken for length, width, and area of the structures, both directly and normalized by the tibial plateau width.

Subsequently, comparative statistical analysis was conducted to identify significant differences between the human knee and animal species.

Different aspects of the knees of the seven species. [1]
Passive range of motion showed differences between quadruped animals and the human knee.The study found differences in the size and shape of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and menisci between species.Quantitative differences were observed in ACL and PCL dimensions between species, with variations in length and width.Tibial index, which normalizes measurements by tibial plateau width, showed variations in certain dimensions.Notch width, medial meniscus, and lateral meniscus dimensions varied between species.Anatomical differences were observed in the attachments and origins of ligaments and menisci in different species.Some animal models closely resembled specific aspects of human knee anatomy.

The study highlights the significance of choosing appropriate animal models for knee surgery research.Differences in passive range of motion between quadruped animals and humans need to be considered.Various animal models have distinct anatomical characteristics, making certain species more suitable for specific aspects of knee research.

The study provides insights into the size, shape, and anatomy of knee structures across human and animal species.

To conclude, different animal models may be suitable for various types of knee surgery research based on anatomical similarities to the human knee.

Learn More:

Proffen, Benedikt L., Megan McElfresh, Braden C. Fleming, and Martha M. Murray. “A comparative anatomical study of the human knee and six animal species.The Knee 19, no. 4 (2012): 493-499.


This article was written by Elisa Bissacco as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

She is studying a PhD in Tribological Characteristics of Nanofibrous Electrospun Materials at ETH Zurich.

Point of Care 3D Printing

Header Image: A 3D printed acetabulum. Credit Arcam

The field of medical engineering is undergoing a transformative shift with the integration of 3D printing technology into point-of-care orthopaedics. This innovative approach has the potential to revolutionize orthopaedic treatments by reducing lead times, enhancing device fit, and minimizing material waste.

Point of care refers to the location or setting where medical diagnostics, treatments, and interventions are provided directly to patients, often in immediate proximity to the patient, facilitating rapid and convenient healthcare delivery.

Benefits of 3D Printing in Orthopaedics:
3D printing is poised to address long-standing challenges in orthopaedics, offering a fresh perspective on patient care. 3D printing introduces a sustainable approach to orthopaedics by minimizing material waste. Unlike traditional manufacturing methods, which often result in excess material usage, 3D printing enables precise fabrication, contributing to both cost savings and environmentally friendly practices (1).

Additionally, by enabling the on-site printing of bespoke medical components, 3D printing unlocks a new level of personalization, potentially resulting in improved patient outcomes (1).

This technology, that can be based all on site, has the capacity to significantly reduce lead times for patient with unique requirements where standard devices are not appropriate, which is of paramount importance, particularly in urgent and emergency situations.

Challenges and Considerations:
While the potential benefits of 3D printing in orthopaedics are immense, challenges persist. Mechanical losses during the 3D printing process can impact the durability and mechanical properties of orthopaedic devices (2). Furthermore, questions arise about the performance of 3D printed devices in tribological environments. Addressing these challenges requires ongoing research and development to optimize the technology for orthopaedic applications.

Future Possibilities:
The integration of 3D printing into point-of-care orthopaedics paints an exciting picture for the future. The ability to create personalized orthopaedic solutions on site holds promise for reducing lead times, minimizing material waste, and enhancing patient-specific implant designs. This technology has the potential to reshape the landscape of orthopaedic care and contribute to more efficient and patient-centred treatments.

The convergence of 3D printing and orthopaedics signifies a paradigm shift in medical engineering. The ability to print bespoke medical devices directly at the point of care offers a glimpse into a future where orthopaedic treatments are more tailored, efficient, and sustainable. As we navigate the challenges and opportunities presented by 3D printing, it is clear that this technology has the power to redefine the way we approach orthopaedic care, ultimately leading to improved patient outcomes and a more responsive healthcare system.



[1] Teo, A.Q.A., Ng, D.Q.K., Peng, L.E.E. and O’NEILL, G.K., 2021. Point-of-Care 3D printing: A feasibility study of using 3D printing for orthopaedic trauma. Injury52(11), pp.3286-3292.

[2] Bastawrous, S., Wu, L., Liacouras, P.C., Levin, D.B., Ahmed, M.T., Strzelecki, B., Amendola, M.F., Lee, J.T., Coburn, J. and Ripley, B., 2022. Establishing 3D printing at the point of care: basic principles and tools for success. Radiographics42(2), pp.451-468.


This article was written by Ben Clegg part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Ben is researching the Wear particle characterization and bio-compatibility of newly 3D printed self-lubricating polymer composites in total joint replacements at Luleå University of Technology, Sweden.

Dual effect of 3D printing Femoral Stems

Header Image: credit to Ntop, and TU Delft


In the ever-evolving landscape of medical advancements, the marriage of 3D printing technology and topology optimization has unlocked remarkable potential in the realm of hip implants. This dynamic duo not only promises enhanced osseointegration but also addresses a critical concern – stress shielding. In this article, we delve into the groundbreaking innovation of reduced stress shielding through topologically optimized hip implants, a feat that’s transforming the way we approach orthopaedic care.

Understanding Stress Shielding

Picture this: A metal implant is introduced into a patient’s body to replace or support a damaged hip joint. Over time, the implant takes on the mechanical stresses that would naturally be borne by the surrounding bone. While this may seem like a solution, it triggers a phenomenon known as stress shielding. As the implant shoulders the load, the bone experiences reduced stress, causing it to lose density and strength. This weakened bone becomes susceptible to fractures and dislocations, negating the intended benefits of the implant.

The Perfect Harmony: Topological Optimization and 3D Printing

Enter topological optimization, a design approach rooted in mathematics that seeks to distribute stresses and strains efficiently within a structure. In the realm of hip implants, this technique takes on a revolutionary role. Combining topological optimization with the precision of 3D printing allows medical device manufacturers to craft implants that not only match a patient’s bone stiffness and density but also counteract stress shielding.

A shining example of this synergy comes from the tech prowess of IT company Altair. By harnessing the power of topological optimization software, Altair embarked on a quest to redesign the conventional hip implant.

Crafting the Future: A 3D printed Topologically-Optimized Hip Implant

Imagine a hip implant created not as a standardized component but as a bespoke masterpiece, uniquely tailored to an individual’s requirements. Armed with parameters like size, weight, and anticipated load-bearing capacity, topology optimization software worked its magic. The result? A hip implant design that ingeniously distributes stress and strain, mimicking the body’s natural mechanics.

But that’s not all. The application of topology optimization extended further, revealing areas where material could be substituted with intricate lattice structures. This strategic modification not only lightened the implant but also elevated its structural integrity.

The Game-Changing Results

The true testament of any innovation lies in its real-world impact. In one case, the topologically-optimized hip implant demonstrated a staggering 50.7% reduction in stress shielding (1). This means that the implant’s presence didn’t compromise the bone’s strength. Additionally, the implant exhibited an endurance limit that could endure a jaw-dropping 10 million cycles – equivalent to jogging from Los Angeles to New York and back, not just once but twice!


The path to innovation is seldom without obstacles. As we celebrate the potential of topologically-optimized hip implants, we must also acknowledge the challenges that lie ahead.

  1. Sterilization Difficulties: 3D-printed implants introduce new considerations in sterilization. The intricate lattice structures that contribute to implant performance may also harbor contaminants, necessitating novel sterilization techniques that preserve the implant’s structural integrity.
  2. Corrosion Concerns: The unique geometries and materials used in 3D printing can introduce corrosion risks. Addressing this challenge requires the development of corrosion-resistant materials and surface treatments to ensure the implant’s long-term viability.

A Glimpse into the Future

If we can overcome these challenges, the fusion of topological optimization and 3D printing has bestowed the medical world with a transformative tool. As we witness stress shielding dissipate before our eyes, we catch a glimpse of the future – one where hip implants, and potentially other medical devices, become personalized marvels, engineered to harmonize seamlessly with the human body.

In closing, the convergence of mathematical ingenuity and cutting-edge technology is sculpting a path towards a new era of orthopaedic care. Reduced stress shielding is no longer a distant dream; it’s a reality that holds the promise of stronger, healthier tomorrows for patients around the world.


Learn More:


7 Complex Designs Achieved With 3D Printing


This article was written by Ben Clegg part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Ben is researching the Wear particle characterization and bio-compatibility of newly 3D printed self-lubricating polymer composites in total joint replacements at Luleå University of Technology, Sweden.