The ornamental design for a lateral decubitus legsupportdevice, as shown and described.
FIG. 1 is a front, right perspective view of a lateral decubitus leg support device;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a right side elevation view thereof; and,
FIG. 7 is a left side elevation view thereof.
The dash lines in the drawings depict portions of the lateral decubitus leg support device that form no part of the claimed design. The dot dash dot broken lines depict the boundaries of the claim and form no part thereof.