An apparatus comprises an implantable mechanically adjustable band (148) configured to form a restriction in a patient. The band defines an inner diameter (180). The mechanical adjustability of the band is configured to permit the inner diameter defined by the band to be selectively varied. The apparatus further comprises an adjustment mechanism (150,152) in communication with the band. The adjustment mechanism is operable to provide the mechanical adjustability of the band. The apparatus further comprises a sensor (304) in communication with one or both of the mechanically adjustable band or the adjustment mechanism. The sensor is configured to sense a physical parameter associated with operation of the band. The physical parameter sensed by the sensor varies with the inner diameter defined by the band. The band may be used as a gastric band, among other potential uses.
