HIP Star: tracing early risk factors for future hip osteoarthritis
Hip osteoarthritis is usually noticed when people start to experience pain, stiffness or difficulty moving. By then, the disease process may already be well underway. There is currently no cure for osteoarthritis. Most treatment options focus on reducing symptoms, and when these no longer help, hip replacement surgery may become the last option. But what if part of the risk starts much earlier in life, while the hip joint is still developing?
HIP Star is one of the research projects within the Convergence Health & Technology Flagship Healthy Joints. The Flagship focuses on prevention, early diagnosis, and personalized treatment of osteoarthritis. HIP Star contributes to that ambition by studying how the hip joint develops during childhood and adolescence, and how this may influence the risk of hip osteoarthritis later in life.
For a common and disabling disease that cannot be reversed once it has developed, you need to consider whether its onset can be prevented,
Why prevention matters
Osteoarthritis is expected to become the most common chronic disease in the Netherlands by 2040. Hip osteoarthritis can be severely disabling. It can affect walking, working, exercising, and staying independent, and is associated with high healthcare and societal costs, including surgery and effects on workforce participation.
Despite this impact, primary prevention (preventing hip osteoarthritis before it develops) has received limited structural attention, especially when it comes to risk factors that arise while the hip joint is still developing. A crucial first step is to identify causal risk factors and understand how they may lead to disease.
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An early risk factor: hip dysplasia during childhood
HIP Star focuses on one of those risk factors: the development of hip dysplasia during childhood. In hip dysplasia, the socket of the hip joint does not sufficiently cover the head of the femur. This under-coverage is known to be an important risk factor for future hip osteoarthritis.
To better understand how hip dysplasia develops, HIP Star studies the hip joint during childhood and adolescence. Using the Generation R cohort, a long-term population study following children in Rotterdam, researchers assess hip development from around the age of 6 until 18. This makes it possible to study growth over time, rather than only looking at the joint at one single moment.
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From 2D measures to 3D biomarkers
The team uses existing DXA images, a type of scan, to measure in 2D how well the hip socket covers the head of the femur and to follow how this coverage changes as children grow. In addition, the researchers are developing new 3D biomarkers based on MRI images. These provide a more detailed picture of hip shape and coverage and make it possible to study how the hip changes during childhood and adolescence.
Together, these methods help the team better understand how hip coverage develops, how hip dysplasia may arise, and which mechanisms may contribute to future hip osteoarthritis.
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A concrete output: Making hip morphology measurable in 3D
HIP Star has already led to the development of an automated method to measure hip morphology (the shape and structure of the hip) using advanced 3D imaging biomarkers. The method has been applied to scans taken before and after periacetabular osteotomy, a hip-preserving surgery used to correct hip dysplasia.
By comparing hip shape before and after surgery, the method enables a more objective, patient-specific assessment of changes in acetabular orientation and femoral head coverage.
| Signed surface distance maps of pre- and post-operative hip morphology relative to the mean anatomy of a general population. The visual shows how 3D imaging biomarkers can be used to quantify patient-specific changes in hip shape and femoral head coverage. |
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What this could change
The knowledge and methods developed within HIP Star may have value in two ways.
In the shorter term, the 3D assessment method could support more precise evaluation of hip-preserving surgery, such as periacetabular osteotomy. By quantifying changes in hip morphology before and after surgery, it may help assess surgical outcomes and reduce reliance on subjective or 2D measures. In the future, this could contribute to more consistent, data-driven pre-operative planning and post-operative evaluation.
In the longer term, HIP Star aims to contribute to prevention. By identifying risk factors that may play a causal role in hip dysplasia and understanding how they affect hip joint coverage during growth, HIP Star aims to support future strategies that could influence hip development, reduce the risk or severity of hip dysplasia, and ultimately lower the future impact of hip osteoarthritis.
Hip replacement should be the last resort, not an early one. By intervening while the joint is still modifiable, we aim to keep that option as far away as possible for young patients
What comes next: from risk factors to prevention
The next step is to move from describing differences in hip shape to understanding why these differences develop during growth. To do this, the team will use imaging data to build models that can help explain how hip coverage changes during childhood and adolescence, and which risk factors may play a role.
Eventually, the team aims to create finite element models: computer models that can simulate how risk factors such as body weight or physical activity may affect the developing hip joint. These models can then be used to explore what might happen if certain risk factors change.
If the models show changes in hip dysplasia that are meaningful for future care, and if potential interventions are identified, clinical trials could be designed to test preventive interventions in human populations.
HIP Star is still a research project, not a prevention program in practice yet. But it points to an important shift: from treating hip osteoarthritis once damage has occurred, toward understanding whether part of the disease risk can be addressed earlier, while the joint is still developing.
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The power of convergence
HIP Star brings together a diverse group of experts. From Erasmus MC, the project includes expertise in early-stage osteoarthritis, orthopedics, pediatrics, technical medicine and medical image processing. TU Delft contributes expertise in medical and biomechanical engineering, biomaterials and tissue biomechanics, and machine learning.
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This combination is important because the question behind HIP Star is too complex for one discipline alone. Clinicians bring in the patient and care perspective, imaging and data specialists help extract reliable information from complex imaging datasets, and biomechanical engineers help model how risk factors may influence the developing hip joint.
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That is where Convergence adds value: it connects these perspectives around one shared goal: moving from treating hip osteoarthritis after damage has occurred toward exploring whether risk factors for hip dysplasia can be understood, modeled and, in the future, influenced while the joint is still developing.
A better understanding of AD development during growth is crucial, as this knowledge can inform prevention strategies for AD, and consequently, mitigate the risk of OA in younger individuals.
Linked in of the researchers involved: