The ornamental design for a kneesupportmassager, as shown and described.
FIG. 1 is a top plan view of a knee support massager showing my new design;
FIG. 2, is a bottom plan view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof; and,
FIG. 6 is a right side elevation view thereof.
The broken lines around the perimeter of the knee support massager and across the ends thereof in FIGS. 1 & 2 represent stitching and from no part of the claimed design. The remaining broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design.