Ultrasonographic Assessment of Diurnal Variation in the Femoral Condylar Cartilage Thickness in Healthy Young Adults

Objective In vivo measurement of articular cartilage thickness is a significant marker of structural joint damage in many inflammatory or noninflammatory diseases including rheumatoid arthritis or osteoarthritis. The aim of this study was to assess the diurnal variation of femoral condylar cartilage thickness (FCT) in young adults by using ultrasonography. Design The thickness of femoral articular cartilage was measured in healthy volunteers at 8:00-9:00 a.m. and 4:00-5:00 p.m. on the same day using standard sonographic methods. Three midpoint measurements were taken from each knee at the lateral femoral condyle, femoral intercondylar area, and medial femoral condyle. Results The FCT significantly decreased in all the areas assessed. The maximal decrease (in millimeters) in the mean (standard deviation) FCT was in the right lateral femoral condyle (0.21 [0.24]) and left medial femoral condyle (0.21 [0.21]) followed by the right medial femoral condyle (0.19 [0.23]), left lateral femoral condyle (0.19 [0.19]), left femoral intercondylar area (0.13 [0.30]), and right femoral intercondylar area (0.11 [0.33]). The mean diurnal change in FCT from a.m. to p.m. reached up to 10.6%. Conclusions This study suggests that the FCT significantly decreased in all of the measured areas from a.m. to p.m. Future studies, particularly those assessing the effect of any pharmacologic or nonpharmacologic applications on cartilage thickness in the weight-bearing joints, should be designed bearing in mind that cartilage thickness has diurnal variations. Assessment of diurnal variation in cartilage thickness in elderly osteoarthritic or nonosteoarthritic populations warrants further research.