Sternal ascender apparatus

An apparatus comprising:

• an elongated linear actuator gear extending along an actuator axis from a first end to a second end, the linear actuator gear having a plurality of teeth that each extend normal to the actuator axis, wherein the plurality of teeth cooperate to define a plurality of recesses, wherein each of the plurality of recesses is disposed between a pair of adjacent teeth of the plurality of teeth;
• a rack housing extending along the actuator axis, wherein the rack housing is coupled to the linear actuator gear and the liner actuator gear is configured to displace along the actuator axis relative to the rack housing;
• a cylinder gear comprising:
• a base portion coupled to the rack housing and configured to rotate relative to the rack housing about a gear axis that is normal to the actuator axis, the base portion comprising:
• a first surface;
• a second surface;
• a circumferential surface extending between the first surface and the second surface, wherein the circumferential surface extends in a direction parallel to the gear axis;
• and
• a first locking notch formed in the circumferential surface;
• and
• a first post extending from the first surface of the base portion such that the first post is configured to be disposed within a first of the plurality of recesses;
• a second post extending from the first surface of the base portion such that the second post is configured to be disposed within a second recess of the plurality of recesses,
• wherein when the base portion rotates in a first rotational direction about the gear axis, the first and second posts engage a first portion of the plurality of teeth to displace the linear actuator gear in a first linear direction, and
• wherein when the base portion rotates in a second rotational direction about the gear axis, the first and second posts engage a second portion of the plurality of teeth to displace the linear actuator gear in a second linear direction;
• and
• an elongated limiting pawl pivotably coupled to a portion of the rack housing, the limiting pawl extending from a first end to a second end, wherein an engagement portion of the limiting pawl is disposed at or adjacent to the first end of the limiting pawl, wherein the limiting pawl is pivotable about a pivot axis between an engaged position and a disengaged position, wherein the pivot axis is disposed between the first end of the limiting pawl and the second end of the limiting pawl, the limiting pawl further comprising:
• a locking arm that extends from the first end of the limiting pawl to the pivot point of the limiting pawl;
• and
• a release arm that extends from the pivot point of the limiting pawl to the second end of the limiting pawl,
• wherein when the base portion rotates in the first rotational direction about the gear axis, the engagement end of the limiting pawl is configured to contact a portion of the first locking notch, thereby preventing further rotation of the base portion in the first rotational direction and preventing further displacement of the linear actuator gear in the first linear direction, and
• when the base portion rotates in the second rotational direction about the gear axis, the engagement end of the limiting pawl is configured to not contact the portion of the first locking notch, thereby allowing rotation of the base portion in the second rotational direction and allowing displacement of the linear actuator gear in the second linear direction.