A surgical control instrument for a guidewire comprising: a grip comprising two semi-cylindrical components (112a, 112b) which surround an aperture through which a guidewire can be passed, in which the semi-cylindrical components are movable radially relative to the guidewire from a first position to a second, compressed position, and in which the semi-cylindrical components each comprise an inner surface and a thread positioned on the inner surfaces; a first component comprising two gripping members (220a, 220b) which are moveable from a first position in which the guidewire can move axially relative to the gripping members, to a second position in which the gripping members approach one another about the guidewire to fixedly engage the guidewire; and a second, cylindrical rotatable component, wherein rotation of the second cylindrical rotatable component causes the gripping members (220a, 220b) to move axially, only when the gripping members are in their second position, thereby moving the guidewire axially; a screw-engaging portion connected to the second cylindrical rotatable component such that the screw-engaging portion rotates as the second cylindrical rotatable component rotates; a handle which rotates the second cylindrical rotatable component; a releasable locking mechanism between the second cylindrical rotatable component and the handle such that the second cylindrical rotatable component can only rotate when the gripping members (220a, 220b) are in the second position; in which movement of the semi-cylindrical components (112a, 112b) of the grip to the compressed position causes (a) the gripping members (220a, 220b) to move to the second position in engagement with the guidewire, and (b) the gripping members to engage the thread on the inner surfaces of the semi-cylindrical components so that the gripping members are rotated with the second cylindrical rotatable component to cause axial movement of the gripping members and the guidewire. a grip comprising two semi-cylindrical components (112a, 112b) which surround an aperture through which a guidewire can be passed, in which the semi-cylindrical components are movable radially relative to the guidewire from a first position to a second, compressed position, and in which the semi-cylindrical components each comprise an inner surface and a thread positioned on the inner surfaces; a first component comprising two gripping members (220a, 220b) which are moveable from a first position in which the guidewire can move axially relative to the gripping members, to a second position in which the gripping members approach one another about the guidewire to fixedly engage the guidewire; and a second, cylindrical rotatable component, wherein rotation of the second cylindrical rotatable component causes the gripping members (220a, 220b) to move axially, only when the gripping members are in their second position, thereby moving the guidewire axially; a screw-engaging portion connected to the second cylindrical rotatable component such that the screw-engaging portion rotates as the second cylindrical rotatable component rotates; a handle which rotates the second cylindrical rotatable component; a releasable locking mechanism between the second cylindrical rotatable component and the handle such that the second cylindrical rotatable component can only rotate when the gripping members (220a, 220b) are in the second position; in which movement of the semi-cylindrical components (112a, 112b) of the grip to the compressed position causes (a) the gripping members (220a, 220b) to move to the second position in engagement with the guidewire, and (b) the gripping members to engage the thread on the inner surfaces of the semi-cylindrical components so that the gripping members are rotated with the second cylindrical rotatable component to cause axial movement of the gripping members and the guidewire.