Surgical drill instrument with motor and locking mechanism to receive an attachment and a cutting burr

A method of loading a cutting burr in a surgical drill, the surgical drill comprising a motor, a locking mechanism and a detachable attachment, cutting burr having a shank portion defining a first diamond-shaped portion and an axially spaced second diamond-shaped portion, the locking mechanism including a loading position and a running position, the method comprising:

• attaching the detachable attachment to the locking mechanism such that the locking mechanism is in the loading position such that a distal end of the locking pawl is received within a portion of the surface at a distal end of the spindle;
• braking a spindle of the locking mechanism and holding a locking pawl of the locking mechanism in a detached position;
• inserting the cutting burr into the surgical drill through an end of the detachable attachment and into the spindle of the locking mechanism such that the first diamond-shaped portion of the shank of the cutting burr fits into a defined key slot in the spindle and such that the second diamond-shaped portion is engaged by a detent pawl to hold the cutting burr in the surgical drill while providing a predetermined amount of axial movement of the cutting burr;
• and
• placing the surgical drill in the running position by moving the detachable attachment to cease braking of the spindle and to cause an engagement end of the locking pawl, opposite the distal end, to engage the second diamond-shaped portion of the shank to lock the cutting burr in the surgical drill with substantially no axial movement.

A surgical drill, comprising:

• a cutting burr including a shank defining a first six-sided portion and a second six-sided portion;
• a spindle rotatable about a central axis, the spindle defining a keyed slot adapted to receive the first diamond-shaped portion of the shank of a cutting burr;
• a locking mechanism releasably mounted to the spindle;
• a locking pawl pivotally attached to the spindle and having a distal end received on a portion of the surface at a distal end of the spindle when the locking mechanism is in the loading position and an engagement end adapted to engage adjacent facets of the second diamond-shaped portion of the cutting burr received within the locking mechanism;
• a detent pawl having a lever pivotally connected to the spindle, the detent pawl having an engagement end portion and a biasing end portion for pivoting the engagement end portion to fit into the second diamond-shaped portion;
• and
• a motor for driving the spindle and the locking mechanism,
• wherein the engagement end portion of the detent pawl engages the second diamond-shaped portion at a location opposite to where the engagement end of the locking pawl engages the cutting burr.