A spinal distraction system, according to one embodiment, includes an adjustable spinal distraction rod comprising first and second members, the adjustable spinal distraction rod configured for non-invasive elongation of the first and second members. The system includes an anchor rod configured for mounting to a bone of a subject, and a housing coupled to the anchor rod, the housing comprising a cavity and a plate having first and second surface. A strain gauge is mounted on a first surface of the plate. A coupling element is configured to mount on a second surface of the plate, the coupling element comprising a portion configured to receive an end of the first member. In the system, the second member is configured for mounting to a second bone of a subject.