An intervertebral prosthesis for implantation between adjacent vertebrae of the human spine is shown. In particular, the invention is concerned with a hydrocolloid dressing which is absorbent, non-damaging to the skin and comfortable to the user preferably having at least a thermoplastic elastomer backing and water absorbent polymeric adhesive layer. The device also including a stopper element extending from the distal end of the attachment mechanism and projecting away from the longitudinal axis, the stopper element being bendable in a direction toward the proximal end of the attachment mechanism. The control amplifier circuit controls a first voltage provided to a first control node and a second voltage provided to a second control node in response to the detection results. Button labels may be easily replaced in the button assemblies.