Comparison of knee joint cartilage thickness in triathletes and physicallyinactive volunteers based on magnetic resonance imaging and three-dimensional analysis

The objective of this study was to employ quantitative magnetic resonance i maging for the analysis of knee joint cartilage thickness in triathletes an d physically inactive volunteers. The right knee joints of nine male triath letes (10 hours training per week for at least 3 years) and nine inactive m ale volunteers (1 hour of physical activity per week throughout life) were imaged with a previously validated fat-suppressed gradient echo sequence. T he cartilage plates were reconstructed three-dimensionally, and the cartila ge thickness was computed independently of the original section orientation with a three-dimensional Euclidian distance transformation. There was a hi gh interindividual variability of the mean and the maximal cartilage thickn ess values in all surfaces, both in the triathletes and in the inactive vol unteers. In the patella, the femoral trochlea, and the lateral femoral cond yle, the mean and maximal cartilage thickness values were slightly higher i n the triathletes, but they were somewhat lower in the medial femoral condy le, and in the medial and lateral tibial plateau. However, the differences did not attain statistical significance. These results are unexpected in vi ew of the functional adaptation observed in other musculoskeletal tissues, such as muscle and bone, in which a more obvious relationship with the magn itude of the applied mechanical stress has been observed.