A control assembly for implantation in a patient comprises a first unit adapted for subcutaneous implantation at a first side of a body tissue of said patient, a second unit adapted for implantation in a body cavity of said patient at a second side of said body tissue, wherein at least one of the first and the second unit is adapted to control an implanted powered medical device, and an interconnecting device adapted for mechanical interconnection of the first and second units to keep the assembly in place by the body tissue, the interconnecting device having a cross-sectional area which is smaller than the cross-sectional area of the first unit and the second unit in a plane parallel to the extension of the body tissue.