A system for spinal surgery includes a prosthesis comprising a plurality of bone anchors which engage an intervertebral construct for fusion or motion preservation. The shell is provided inside with a retractable cutter set consisting of a slide block, a cutting blade and a push button. The invention further relates to a fastener including a stud having a locking cavity, an aperture adapted to receive the stud, a locking means adapted to engage the locking cavity, a shuttle rotatable by rotating means including material adapted to contract when activated and a plug slidable within the shuttle to close off the aperture when not occupied by the stud. The first compression stage is operated as a cold compressor and the resulting cold compressed natural gas is employed in the heat exchanger to effect the necessary cooling of the flow from the compression stage. In embodiments, replacing lossy permanent magnets andor electromagnets in even one of the resonators of a wireless power system may be advantageous to system performance. A generator is electrically connected to the storage cell for applying voltage to and recharging the storage cell.