An adjustment tool enables manipulation of a prosthetic anatomical device such as an annuloplasty ring. The tool includes a compression member which is operative for retarding rotation of the adjustment shaft to preclude inadvertent rotation thereof during use of the tool by the surgeon. A locking device is associated with the adjustment tool to enable the releasable attachment of the tool to the anatomical device during its adjustment by manipulation of the tool. The locking device is oriented into operative and inoperative positions by the engagement and disengagement of locking elements. A scale may be provided on the adjustment tool to assist a surgeon in determining the size or amount of adjustment to the size of the anatomical device during its adjustment.