Fig. 2

Relationships with age of overall joint grade (a), concentration of protein (c _Pro ) (b), and concentration of hyaluronan (c _HA ) (c). Data from cadaver (black diamond) and patient joints (blue circles) are shown. Slope (in percent per decade of age) and intercept (percent) of the best-fit line in the form of \( 100y/y(21)=m\hbox{'}\left(x/10\right)+b\hbox{'} \), the coefficient of determination (R²), and significance of the regression are shown. Because of the agreement between left and right knees, statistical analyses were performed using the average of data from left and right knees from each donor, if available. n = 28–36 donors