MRI scans show early knee joint damage is common in symptom-free adults in their thirties.
Mild structural changes in the knees are showing up on MRI scans in adults as young as their early thirties—even in people who have no knee pain or symptoms at all. In a new study from the University of Oulu, researchers discovered signs of early joint damage in more than half of the 33-year-olds they examined. The strongest link to these changes was a higher body mass index (BMI), making weight a key factor in early joint wear.
The findings come from the Northern Finland Birth Cohort 1986 (NFBC1986), a long-running research project tracking the health of thousands of individuals. In this part of the study, 297 participants took part in detailed health assessments. They gave blood samples and underwent magnetic resonance imaging (MRI) scans of their knees. On average, the participants were 33.7 years old.
Common Structural Findings in Knee MRI
The most common findings were minor articular cartilage defects, particularly between the kneecap and thighbone, observed in over half of those imaged. Cartilage defects were also found in the joint between the shinbone and thighbone in about a quarter of participants. In addition, small bone spurs, or osteophytes, were detected in more than half of the group, although these were generally small.
Researchers identified a higher body mass index as the clearest factor linked to the MRI findings.
“Weight in particular seems to be associated with structural changes in the knee joint, as height had a much smaller effect compared to body mass index. These results highlight the importance of weight management in preventing joint diseases,” says Joona Tapio, a specialist trainee doctor and researcher at the Faculty of Biochemistry and Molecular Medicine.
Implications for Imaging and Clinical Practice
“The use of knee MRI is increasing, often for very good reasons. Modern imaging technologies reveal even minor osteoarthritis-like changes. As with lumbar spine imaging, it is crucial to interpret knee findings within the broader clinical context and to adhere to appropriate imaging guidelines,” says Antti Kemppainen, radiologist and researcher at the Faculty of Medicine.
Although most participants were asymptomatic, the findings suggest that structural changes in joints can occur before clear symptoms develop. The researchers stress the need for longitudinal studies to determine which factors predict the progression of these changes later in life.
Reference: “Structural knee MRI findings are already frequent in a general population-based birth cohort at 33 years of age” by Antti Kemppainen, Joona Tapio, Miika T. Nieminen, Simo Saarakkala and Mika T. Nevalainen, 17 April 2025, Osteoarthritis and Cartilage.
DOI: 10.1016/j.joca.2025.04.008
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