Medical implants can comprise various instrumentation to impart desirable functionality to the implant. In some embodiments, the implants comprise functional structures, such as sensors, energy propagating transducers, drug delivery systems and the like. Additional instrumentation to facilitate the functionality of these devices can include, for example, microprocessors, communication systems, power sources or the like. Drug delivery systems can comprise, for example, an isolated reservoir with a control system to control the delivery of a biological agent from the reservoir. The implants can be orthopedic implants that are designed to interface with a patient's skeletal system wherein the orthopedic implant may itself embody sensors, processors, power supplies, memory and/or communication capability.