The invention relates to an apparatus for fixing a ligament, which comprises a bone-anchoring element having a proximal end and a distal end which has a bore running in the longitudinal direction, and which comprises a clamping sleeve having a proximal end and a distal end, which clamping sleeve can be accommodated in the bore. The clamping sleeve is radially expandable, with the result that the ligament can be fixed between the clamping sleeve and the bore of the bone-anchoring element.