Various methods and devices are provided for constraining movement between two housings implanted under the skin. In one embodiment, a restriction system is provided and includes a first housing having a reservoir formed therein and configured to receive fluid, and a second housing spaced apart from and in fluid communication with the first housing. The second housing can have a sensor, for example, for measuring fluid pressure. A restriction device can be in fluid communication with the first and second housings and can be adapted to form a restriction in a pathway. A constraining element can be coupled to the first and second housings and can be configured to limit movement of the first and second housings relative to one another in at least one plane of motion.