A telemetering system using an elongation sensor in conjunction with an implantable transmitter is described. The transmitter can be turned on and turned off by use of a pulsed radio-frequency source and has a useful life in excess of two months. The sensor is a newly developed device capable of giving a usable signal when elongated by as little as 0.05 mm. It is fabricated from commonly available material and can be constructed by any reasonably skilled technician.