An adjustable
implant (300, 330, 358, 386, 400, 420, 444, 462, 1000) for
wireless adjustment of a dimension within a body, comprises a first portion (301, 334, 360, 396, 404, 422, 458, 472), configured for
coupling to a first location in the body; a second portion (302, 336, 364, 398, 406, 424, 450, 464), configured for
coupling to a second location in the body; and a magnetic drive configured to adjust a relative distance between the first portion and the second portion. The magnetic drive includes at least one driven
magnet (304, 340, 366, 381, 402, 432, 454, 478, 1010) configured to revolve about an axis in response to a
magnetic field imposed by a driver
magnet (510, 511; 606, 608; 706, 708; 1106, 1108) outside of the body. The adjustable
implant is configured to transmit a
signal indicative of the responsiveness of the driven
magnet to the driver magnet. A change in the responsiveness is indicative of a change in a force applied between the body and the first and second portions.