Regional dependency of sex differences in height-adjusted knee cartilage thickness in KL0 knees using 3D-MRI

The prevalence of knee osteoarthritis (OA) is higher in females than in males, possibly due to cartilage characteristics. However, studies examining sex differences in normal knee cartilage thickness, particularly those that adjust for height and regional variation, remain limited. This study examined sex differences in cartilage thickness across six regions of Kellgren-Lawrence grade 0 (KL0) knees, using sex, height, and age as explanatory variables.

KLO knees in the Kanagawa Knee Study (n = 573) were analyzed using automated KL-grading software. Cartilage thickness was quantified using automated three-dimensional magnetic resonance imaging (3D-MRI) in six regions: the medial femur (MF), medial tibia (MT), lateral femur (LF), trochlear femur (TrF), lateral tibia (LT), and patella (P). Multiple regression analysis was performed using sex, height, and age as explanatory variables. Uncorrected cartilage thickness was compared among regions for each sex using one-way analysis of variance (ANOVA). Statistical significance was set at P < 0.05.

The study included 306 KL0 knees (138 females, 168 males), with females being younger and shorter than males. After height adjustment, females showed significantly thinner cartilage in the MF, MT, LF, and TrF regions, while the LT and P regions showed no sex differences. All regions showed positive correlations between cartilage thickness and height. In both sexes, the P region had the thickest cartilage, followed by LT.

Sex differences in cartilage thickness showed regional dependency in KL0 knees. While most regions showed thinner cartilage in females after height adjustment, the LT and P regions, characterized by greater cartilage thickness, showed no sex differences.