The present invention relates to a an attachment device for attaching aprosthesis to a bone, comprising a base platehaving an extension in an xy- plane, a first holder for holding a firstabutment, a second holder for holding a second abutment, alocking plate attached to the base plate to restrict movement of the holders ma z-direction away from the base plate The lockingplate is configured to allow rotation of the first and second holder around az-axis perpendicular to the xy-plane The locking plateand the base plate is configured to allow movement of the first holder alongthe x-direction and to prevent movement the y-directionand to prevent movement of the second holder m the x-and y-direction. At leastone flexible member is arranged between each of thefirst and second holdersand the base plate, the flexible member beingflexiblem the z-direction to allow movement of the first andsecond holder in the z-direction and to allow the first and second holder totilt with respect to the xy-plane
