Using a quantitative method to evaluate body ageing, scientists from Dermapro and Kyung Hee University in Seoul, Korea, looked at establishing new grading criteria for severity of wrinkles on knees and investigate the relationship of wrinkle severity with age- and site-dependent.
Their results, which were published in the journal Skin Research and Technology, showed that monitoring visual scoring, skin wrinkle, and elasticity criteria on the knee might be useful for evaluation of ageing not only on the facial sites but also on the body sites.
In the past, skin ageing has been focused more on the face than on the body, with Crow's feet as the main focus, as this is the most representative site to evaluate wrinkles.
Little is known about the age-dependent changes of wrinkles on body sites; however, scientists say that ageing on the knee is highly related to Crow's feet, opening up this site for further evaluation, which the team says it will pursue.
“This study [is the] starting point to research body ageing,” say the researchers. “We will continue to study other sites of the body to compare which site is the most visible for ageing. In addition, other biophysical properties of body ageing will be evaluated.”
In this study, 38 healthy Korean female volunteers were divided into two age groups, and the skin on the knee of each volunteer was photographed, before visual assessment, skin wrinkle, and skin elasticity were evaluated on Crow's feet and the knee.
The knee was chosen as a representative site on the body because it is a site in which muscle movement and UV exposure are considered for other body sites.
Significant differences and the correlation of skin ageing parameters with differing age groups and sites were also examined.
They found that skin wrinkle severity had a significantly positive correlation with age and there was a significant difference between the two age groups.
Also, skin wrinkle parameters were significantly low, and skin elastic parameters were significantly high in the younger group, which showed less wrinkles and higher elasticity on the knee.
The team also compared the biophysical properties on the face and body to see if there was a link between Crow's feet and the knee, and found that all of the parameters displayed similar tendencies of ageing.