What is the test for proving the medical necessity of a cane?

SSR 96-9p provides that "[t]o find that a hand-held assistive device is medically required, there must be medical documentation establishing the need for a hand-held assistive device to aid in walking or standing, and describing the circumstances for which it is needed (i.e., whether all the time, periodically, or only in certain situations; distance and terrain; and any other relevant information). The adjudicator must always consider the particular facts of a case." SSR 96-9p, 1996 WL 374185, at *7. See also Tripp v. Astrue, 489 F. App'x 951, 955 (7th Cir. 2012) (proof of the medical necessity of a cane "require[s] an unambiguous opinion from a physician stating the circumstances in which an assistive device is medically necessary"); Howze v. Barnhart, 53 F. App'x 218, 222 (3d Cir. 2002) (same).