Bone anchors and bone anchor implantation devices can be used to maintain or improve urinary continence by suspending or stabilizing the bladder neck of a patient. A maskant is provided on the workpiece such that a first portion of the workpiece is exposed and a second portion of the workpiece is covered by the maskant. The control valve switches communication of the control chamber between the high-pressure channel and a low-pressure channel. This serves to prevent discharge through the surface of the same printed board serving as a current passage.