Women have thinner cartilage and smaller joint surfaces than men after adjustment for body height and weight.

OBJECTIVE: Females have a higher incidence of knee osteoarthritis (OA) than males, but the reason for this is unclear. Here we examine the hypothesis that women have smaller joint surfaces than men, independent of weight and height, and thus encounter higher articular pressures that might contribute to the higher incidence of OA in the female knee.
METHODS: Forty healthy women and 57 men (21-39 years) with a body mass index of 16.8-32.8 were studied using magnetic resonance imaging. The right knee was scanned and proprietary software was used to determine the area of subchondral bone (cAB), mean cartilage thickness (ThC) and cartilage volume (VC) for all knee cartilage plates. Multilinear regression was used to correct the data for sex differences in height and weight.
RESULTS: cAB, ThC, and VC were larger in men than in women in all knee cartilage plates. Correction for height and weight differences between the sexes reduced but did not eliminate sex differences in these parameters. The cAB was a strong predictor of VC independent of sex, height and weight, but did not predict ThC.
CONCLUSION: Men have greater knee cABs, ThC and VC than females even after correction for height and weight. Nonetheless, estimated tibial and patellar pressures are similar between sexes and thus are unlikely to account for the sex differences in OA incidence.