A heart valve prostheses includes an annular member implantable within a biological annulus, a collar extending upwardly from the annular member, and a sewing ring extending from the annular member. A spring structure couples the collar to the annular member and biases the collar to align with the annular member at a predetermined distance above the annular member. During use, the prosthesis is introduced into a biological annulus, and fasteners are directed through the sewing ring into surrounding tissue to secure the prosthesis with the annular member within the biological annulus. A mechanical or bioprosthetic valve is introduced and coupled to the collar, e.g., using tabs or other connectors on the collar. The spring structure allows the collar to be directed towards the annular member and / or folded inwardly, e.g., to facilitate accessing the sewing ring to deliver fasteners.