What if you could see what happens inside a knee, hip or ankle while someone is walking, climbing stairs or squatting? For people with osteoarthritis, or people at risk of developing it, this question matters. The way a joint is loaded during movement can influence pain, function and disease progression. Yet with standard methods, measuring this accurately during everyday movement is difficult.

Osteoarthritis is a chronic and disabling joint disease. It can cause pain, stiffness and loss of function, and is associated with reduced work productivity, reduced quality of life, higher risk of secondary conditions like heart disease and stroke, and higher mortality. Worldwide, the prevalence of osteoarthritis has increased by more than 30% in the past decade. More than 50 million people in the EU currently live with osteoarthritis of the hip or knee, and cases of knee osteoarthritis alone are projected to increase by 75% by 2050.

Mechanical stress on cartilage and other joint tissues plays an important role in osteoarthritis. Still, researchers do not yet fully understand how joint loading contributes to the onset and progression of the disease. One reason is that directly measuring stress inside a joint is highly invasive and indirect measures of joint stress can be of limited accuracy due to the inability to directly measure how the bones move inside the joint during functional tasks.

That is where the MOBI lab comes in. Short for MOtion Biomechanics & Imaging, the MOBI lab helps researchers study joints while people move. Being a joint laboratory of TUDelft and ErasmusMC, located at Erasmus MC, it is  connected to the Convergence Health & Technology Flagship Healthy Joints.

The MOBI lab: a first-of-its-kind facility in the Netherlands

The MOBI lab is the first facility of its kind in the Netherlands to embed low-radiation video X-ray, also known as fluoroscopy, directly into a biomechanics lab. These combined technologies make it possible to look inside the joint and image how the bones move while someone is moving. What makes the set-up especially valuable is that this can be done during functional movements, such as walking, stair climbing, cycling, or squatting. These movements are close to daily life, allowing researchers to study joint motion in a way that better reflects how people move in the real world.

Because the MOBI lab set-up directly images bone movement during functional activities, it yields gold-standard accuracy and precision. In other words: the lab does more than show how someone moves. It helps researchers understand what that movement means inside the joint.

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From technology to research in practice

Several research projects are now taking place in the MOBI lab. After pilot testing, measurements in patient groups have started. The projects focus on different joints, including knees, hips and ankles. Participants range from adolescents to older adults. They include people without injuries or symptoms, competitive athletes, people at increased risk of osteoarthritis due to obesity or a previous sports injury, people with early or advanced osteoarthritis, and people with a joint replacement.

This broad range is important because osteoarthritis develops over time. Risk factors may be present long before severe symptoms occur. By studying people across different stages and risk profiles, researchers can better understand which movement and loading patterns are linked to healthy joints, increased risk or disease progression.

The lab helps researchers understand how joints respond to different types of loading, from everyday activities to more demanding sports movements.

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Towards more personalized treatment

In the future, insights from MOBI could help researchers better understand how a person moves and whether certain movement patterns place too much stress on the joint. This could help answer clinically relevant questions. Does someone have a loading problem? Could a different way of moving reduce stress on the joint? Could a brace, exercise program, gait retraining or surgical intervention improve how the joint is loaded?

This could be especially relevant for people with osteoarthritis who stop exercising because they fear that movement may worsen joint damage. At the same time, movement is important for joint health. By studying how different movements affect the joint, MOBI could help researchers understand which types of movement may be harmful, helpful or adaptable. This could help tailor treatment or exercise advice more closely to the individual patient.

The next step is to use the personalized digital models and insights to develop and evaluate new treatments and care pathways in clinical studies. More research and validation are still needed but eventually the goal is to become part of routine care.

In the long term, insights from the MOBI lab could support earlier detection and treatment, help prevent osteoarthritis or slow down its progression, and contribute to care that is more closely tailored to the individual patient. It could also help improve pain, function and quality of life, and delay or even prevent invasive treatments such as joint replacement surgery.

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Researchers involved

The MOBI lab is driven by an interdisciplinary team from TU Delft’s Department of BioMechanical Engineering and Erasmus MC’s Departments of Radiology and Nuclear Medicine, Orthopaedics and Sports Medicine, and General Practice. Researchers involved include Dr Erin Macri, Dr Jos Runhaar, Niels Dur, Wouter Schallig, Dr Rianne van der Heijden, Prof. Dr Sita Bierma-Zeinstra, Prof. Dr Edwin Oei, Prof. Dr Ir. Jaap Harlaar, Dr Ajay Seth and Dr Eline van der Kruk, Dr. Mariska Wesseling, Dr. Nazli Tümer, and Sabrina Hörmann. The MOBI lab was inspired by the vision of Prof Harlaar, who together with Prof Bierma-Zeinstra and Prof Oei successfully realized major funding for the lab through a ZonMW Open Competition grant (#09120011910052).