Surgical instrument for the positioning of an alignment element

A patient-specific surgical fixture for positioning an alignment element, comprising:

• one or more patient-specific contact elements configured to fit onto a socket of a ball-and-socket joint, the one or more patient-specific contact elements being configured to contact the socket, wherein a rim of the socket defines at least one of a substantially circular shape having a center defined by a circle best fitting the substantially circular shape or roughly elliptical shape having a center defined by an ellipse best fitting the roughly elliptical shape, wherein the one or more patient-specific contact elements, includes a first contact element, a second contact element, and a third contact element, each of the patient-specific contact elements is configured so that, when fit onto the socket, the first patient-specific contact element contacts the rim at a first contact point, the second patient-specific contact element contacts the rim at a second contact point, and the third patient-specific contact element contacts the rim at a third contact point, wherein a first angle defined by a first line connecting the first contact point and the center and a second line connecting the second contact point and the center measured in in a clockwise direction around the circle or ellipse best fitting the shape from the first line to the second line is not greater than 180°, wherein a second angle defined by the second line and a third line connecting the third contact point and the center measured in the clockwise direction from the second line to the third line is not greater than 180°, wherein a third angle defined by the third line and the first line measured in the clockwise direction from the third line to the first line is not greater than 180°, and wherein the sum of the first angle, the second angle, and the third angle is equal to 360°;
• and
• a positioning element having one or more holes, wherein at least one of the one or more holes is configured to receive the alignment element, and wherein the positioning element is detachably coupled to a connecting structure of the fixture,
• wherein one of the one or more patient-specific contact elements is configured to interact with an anatomical feature present on the socket when fit onto the socket, wherein the anatomical feature is one of a posterior notch of a transverse ligament or a coracoid process.