An interview with co-founder and CEO from 2016-2025 Karianne Lindenhovius

When I first saw the external fixator, I was surprised patients are willing to undergo this treatment. I thought it looked like a kind of torture device. Then I spoke to patients, and they told me it had given them their lives back. They admitted the six-week treatment was tough. They told me about pain relief during the treatment itself, and afterwards they could return to walking, sports, work and an active daily life. Some even said that if their other knee ever failed, they would gladly undergo the procedure again. That is convincing.

How did you find out about knee joint distraction?

At University Medical Center Utrecht I had set up an innovation centre for medical technology called Pontes Medical. With a clinical need as basis, we connected healthcare professionals with engineers and commercial partners to realise innovations. Over the years, we developed around 100 projects. One day, an internal professor in biology and rheumatology approached me about his long-standing research with the orthopaedic surgeon, Dr. Peter van Roermund. They had shown that temporary distracting an arthritic knee joint for 5mm could stimulate the body to repair cartilage using an external device. Together we developed concepts, built prototypes, and tested them with surgeons. We refined the design into what became the KneeReviver.

“The six-week treatment is tough but is nothing if you can get your freedom of movement back.”

At what point were you personally convinced that you should found ArthroSave?

From the start I was building the knee joint distraction business case. The scale of the problem struck me; osteoarthritis is projected to become the number one chronic disease by 2040, which means a huge patient population in need of better solutions.

Unlike most medical innovations, this one already had strong clinical evidence. Peter had years of research and follow-up data from both ankle- and knee joint distraction, much of the groundwork was already covered in many theses. We quickly realized this was the perfect case for a startup since selling to a large orthopaedic company risked the product being sidelined. So, together we decided to start the company ourselves.

Hearing directly from patients that knee joint distraction gave them their active lives back made me believe this was worth pursuing. The six-week treatment is tough but is nothing if you can get your freedom of movement back. And that’s something you can hardly imagine, you don’t have that pain. I got really convinced about the treatment talking to patients, they expressed their desire to undergo the treatment another time for the other knee if needed.

What were some of the initial challenges, and turning points for ArthroSave?

Our biggest challenge was bringing the right people together to build the company. Selling the idea to doctors and patients wasn’t difficult, but finding investment was. Investors struggled to see beyond the unfamiliar external fixator to the quality-of-life benefits for patients. It’s been a decade of highs and lows. Patients understood the value of knee joint distraction immediately; it changed their lives.

When we received the CE certification, clinical adoption expanded. After years of inching from one to five hospitals, adoption suddenly doubled in a single year. Convinced by the strong existing evidence many hospitals chose not to wait for clinical trial results. They started treating patients right away. This created momentum. At our peak, we performed 130 procedures in a year. This breakthrough showed the product market fit of the KneeReviver and resulted in market traction in and outside the Netherlands.

“osteoarthritis is projected to become the number one chronic disease by 2040”

Ten years on, how do you feel about the reach knee joint distraction data has had on patients’ lives and will in the future?

The most important data is the long term 10-year follow-up data. UMC Utrecht has followed 132 patients for 10 years, and the results show that 50% still live with their natural knee. Such a large group makes the evidence convincing and clinically relevant.

Our very first patient had extraordinary results delaying knee replacement by 16 years. Keeping the natural joint for that long is remarkable, and we want to see more patients achieve it. This was already substantial, but I’m eager to see the 15-year results. I believe a significant group will exceed the 10-year survival mark. This strengthens our vision of offering patients a real long-term alternative to early knee replacement.

Personally, looking back, what has been the most rewarding part of this 10-year journey, and where do you hope the next ten years will lead?

The most rewarding part has always been the patients. One example that still stands out is a patient from Switzerland. Out of the blue, he emailed us saying he was thrilled with the knee joint distraction he had undergone, and even sent us a video message, it’s up on our website. Meeting patients like him, those personal connections, is why we do this.

The second has been watching professionals change their minds. At one very early international conference a surgeon bluntly said after Peter’s talk about the clinical and structural effects of knee joint distraction: “I don’t believe you.” Years later, during a panel discussion at a scientific conference surgeons are now advising knee joint distraction for younger OA patients. “Why didn’t you perform knee joint distraction?” they ask. “Talk to the team in Utrecht, they know how to do it.”

In ten years, I hope to see ArthroSave’s KneeReviver widely recognized as standard treatment option for younger patients with severe knee osteoarthritis worldwide. I envision Knee Joint Distraction being integrated into clinical guidelines, reimbursed by healthcare systems, and offered in leading orthopaedic centers across the globe. For me personally, success would mean that we have helped delay hundred thousands of knee replacements per year. Meaning hundred thousands of people living their lives, not limitedby pain.