A system for manipulating a portion of the skeletal system of a mammal includes an implant having a first portion and a second portion, the first portion configured for mounting at a first location of the skeletal system and the second portion configured for mounting at a second location of the skeletal system. The system further includes an adjustment device disposed on the implant and configured to apply a biasing force to the skeletal system, the adjustment device including a magnetic element configured for cyclic movement, the magnetic element being operatively coupled to a drive element configured to alter at least one of the distance or the force between the first location and the second location. The system includes an implantable feedback device operatively coupled to the implant that is configured to produce a response that is indicative of a condition of the implant which can be identified non-invasively.