Systems, methods, and apparatus are described herein for obtaining medical diagnostic measurements from implanted sensors. In various embodiments, a spinal implant-monitoring apparatus may include: a bridge defining a first hermetically-sealed interior and two or more legs; one or more strain gauges contained within the first hermetically-sealed interior of the bridge to provide a signal indicative of strain measured between the legs of the bridge; a housing defining a second hermetically-sealed interior, the housing mounted on a surface of the bridge; and control circuitry contained within the second hermetically-sealed interior. The control circuitry may be in communication with the one or more strain gauges and may be configured to convert the signal into digital data representative of the signal. Methods of using such apparatus are also disclosed.