Surgical knife with retractable blade

A surgical knife, comprising:

• a handle configured to be held by a user, the handle comprising a control member;
• a unitary shaft comprising a distal end and a proximal end opposite the distal end, the proximal end coupled to the handle;
• a rod slidably disposed within a channel of the unitary shaft and comprising a distal end and a proximal end opposite the distal end, wherein the proximal end of the rod is coupled to the control member, and wherein the rod is configured to translate along a longitudinal axis of the unitary shaft upon actuation of the control member;
• a straight blade coupled to the distal end of the rod, wherein translation of the rod causes the straight blade to extend from or retract into the distal end of the unitary shaft;
• and
• a round blade fixedly coupled to the distal end of the unitary shaft at a non-zero angle relative to the longitudinal axis of the unitary shaft;
• wherein the straight blade retracts into the unitary shaft to which the round blade is fixedly coupled;
• wherein the straight blade has a fixed rotational orientation within the unitary shaft relative to the round blade such that a cutting edge of the straight blade is directed away from the round blade thereby allowing the surgical knife to be rotated to switch between the straight blade and the round blade without interference.