Innovative Living Knee Replacement Technology in Development

Imagine a knee replacement crafted from living materials instead of the usual metal and plastic. Researchers from Columbia University and the University of Missouri are on a mission to bring this idea to life. Their 3D-printed knee implant, known as NOVAKnee, consists of a biodegradable scaffold filled with stem-cell-derived bone and cartilage. The expectation is that, once implanted, the scaffold will gradually dissolve, allowing the body to replace it with new bone and cartilage that becomes integrated into the patient’s skeleton.

Traditional knee implants typically last around 20 years and are usually placed in older adults. That’s generally fine for them since they likely only need one implant for the remainder of their lives. However, for younger patients, options are scarce. If they opt for an implant too soon, revision surgery is often on the horizon, while waiting means enduring years of discomfort and restricted movement.

NOVAKnee might provide a more suitable alternative for younger patients. Initial lab tests were conducted on mice, where a small version was implanted under their skin to assess the body’s response. Next, researchers plan to test the implant on larger animals in attempts that mimic human knee replacements, although the specific animals for these tests remain undisclosed.

If everything goes as planned, human trials could commence as early as 2028, supported by a federally funded initiative called Novel Innovations for Tissue Regeneration in Osteoarthritis (NITRO).

In discussions with two key developers — Clark Hung, a professor and vice chair at Columbia University’s School of Engineering, and Nadeen Chahine, a professor of biomedical engineering — they shared insights about the technology.

Nicoletta Lanese: What limitations do conventional knee implants have that NOVAKnee hopes to overcome?

Clark Hung: Conventional knee replacements made from metal and plastic function well, but they generally last only 15 to 20 years. If you’re younger, there’s a good chance you’ll need another implant — a revision surgery — before it fails.

Once the first implant fails, the surgeon needs to carefully remove it to avoid damaging existing bone, which often complicates the insertion of a new implant.

Nadeen Chahine: Older patients often face weakened bone during revision surgeries, leading to a greater risk of instability and failure.

Clark Hung: Therefore, younger patients, especially those who have significant cartilage loss, are often advised to wait, managing pain with medications instead.

The objective here is to help people regain function and eliminate pain. A major challenge is creating a living knee replacement that could potentially eliminate the need for multiple surgeries and offer longer-lasting success compared to current options.

Nicoletta Lanese: Do you see NOVAKnee being beneficial for older patients, too?

Nadeen Chahine: It’s not entirely certain yet. We’ll need more data to identify which patient groups will reap the most benefits. However, there seems to be a clear opportunity to assist younger patients who currently have limited options — basically just injections and temporary measures to manage their pain and limitations.

Nicoletta Lanese: Will this knee replacement procedure be similar to conventional ones?

Clark Hung: Yes, it should be quite similar. We aim to build something that orthopedic surgeons are already familiar with but is, you know, alive.

Nicoletta Lanese: Is it possible to achieve similar results without an implant, perhaps by introducing stem cells directly into the knee joint?

Clark Hung: There are other initiatives aimed at using injectables to regenerate bone and cartilage. Currently, though, there’s nothing on the market that truly meets those needs. Most existing solutions just mask the pain, without addressing the root problem of joint degradation.

In cases of significant damage — where there’s almost no cartilage — something like our proposed implant might be more appropriate since waiting for tissue regrowth might not be feasible.

Interestingly, we joked at the program’s start that effective injectables could spell trouble for us, but I believe there are many people with current implants who will need our product if theirs fail.

Nicoletta Lanese: How did you design the implant’s scaffold?

Nadeen Chahine: The goal is to create a scaffold that promotes a well-defined and controlled bodily response, ultimately degrading over time to leave behind natural components that the body breaks down through its usual mechanisms.

We aimed to create something that mimics the knee’s structure and function but isn’t a permanent foreign material like metal or plastic.

Nicoletta Lanese: How do the stem cells fit into this process?

Nadeen Chahine: We’re working on two versions: one that uses the patient’s own stem cells to create cartilage and bone, called an “autologous” product. The other may utilize donor cells if a patient isn’t a good candidate for autologous therapy.

We still need to figure out the best candidates for each type and the workflow for clinical application. At this point, we’re focused on research and development.

Nicoletta Lanese: In a human patient, how long would the scaffold take to break down and leave the new cells operational?

Nadeen Chahine: That’s quite tricky to predict. We’ve conducted studies on biodegradation and matrix synthesis, but our research so far has mainly been in small animals.

While we have some data on matrix synthesis and degradation rates, we still need to understand how these factors change in a knee environment, particularly under normal usage.

Clark Hung: In our larger preclinical studies, we’re using models of arthritis, effectively simulating osteoarthritis before the living knee replacement occurs, which will closely resemble human clinical scenarios.

Nicoletta Lanese: Are you preparing for human trials already since they might start soon?

Clark Hung: Yes, this initiative is a five-year program with two years for R&D, followed by 18 months of large animal studies, and then an additional 18 months for Phase I clinical trials. If everything aligns perfectly with our animal studies and we get FDA approval, trials could start in about two years, though this timeline is quite optimistic.

Nadeen Chahine: There’s been substantial interest from people — both locally and from further away — inquiring about joining the trial. While we can’t give specific advice yet, we appreciate the enthusiasm. We’ll soon have a form on our website for that interest.

Honestly, it’s both refreshing and enlightening to hear from people who genuinely need something like this, whether it’s friends’ parents or community members reaching out, asking what they can do.

Nicoletta Lanese: Are there noticeable trends among those reaching out? Are they mainly younger patients waiting for knee implants?

Nadeen Chahine: Yes, many seem to be younger individuals hesitant to undergo surgery just yet. They’re managing significant pain without being in the most advanced stages, having given up certain activities they enjoyed.

Clark Hung: Some people also express a preference against having foreign objects in their bodies. If this all works out, especially with autologous cells, the implant essentially becomes part of them as it absorbs.

Nicoletta Lanese: Do you envision this technology being applicable to other types of joint replacements in the future?

Nadeen Chahine: Ideally, yes. Though, to be candid, we wouldn’t have chosen the knee as our starting point. Given its mechanical complexity, it poses considerable challenges. However, it is a crucial area of need. We’d likely focus on other joints with less mechanical complexity for initial proof of concept before expanding.

Nicoletta Lanese: If you had the choice, which joint would you have preferred to start with?

Nadeen Chahine: One of our collaborators noted that the thumb lacks effective replacement options. Despite its small size, it endures high forces, but with a relatively limited range of motion, making it an interesting candidate for development.

Clark Hung: Plus, everyone appreciates having a functional grip, especially with how much we rely on our thumbs for tasks.

Nadeen Chahine: And given how common thumb osteoarthritis is, particularly with increased texting, it’s a growing problem that will only worsen with an aging population.