Withered is used to describe someone's leg or arm when it is thin and weak because of disease or injury. She has one slightly withered leg, noticeably thinner than the other
lean and wrinkled by shrinkage as from age or illness; "the old woman's shriveled skin"; "he looked shriveled and ill"; "a shrunken old man"; "a lanky scarecrow of a man with withered face and lantern jaws"-W F Starkie; "he did well despite his withered arm"; "a wizened little man with frizzy gray hair"
(used especially of vegetation) having lost all moisture; "dried-up grass"; "the desert was edged with sere vegetation"; "shriveled leaves on the unwatered seedlings"; "withered vines"