Two-part screw systems and methods for implanting same

A surgical assembly comprising:

• at least one two-part screw, comprising:
• an inner member comprising a distal end, a proximal end;
• and
• an outer member comprising a distal end, a proximal end, a cannula, and an outer member interference fit portion,
• wherein the inner member is at least partially disposed within the cannula of the outer member and configured to move axially within the cannula between a deployed position and a retracted position, and
• wherein the outer member interference fit portion is configured to trap the inner member within the cannula of the outer member, wherein the proximal end of the outer member includes a pilot hole configured to receive a punch tool for forming the outer member interference fit portion after the inner member has been loaded into the outer member, wherein in the deployed position a distal portion of the inner member is disposed outside the cannula, wherein in the retracted position at least some of the distal portion is disposed inside the cannula;
• at least one outer member driver comprising:
• an outer driver handle,
• a cannulated outer driver shaft, and
• an outer driver proximal end comprising an outer driver engagement part in fixed rotational engagement with an outer member engagement part;
• and
• at least one inner member driver comprising:
• an inner driver handle proximal to the outer driver handle,
• an inner driver shaft within the cannulated outer driver shaft, and
• an inner driver proximal end comprising an inner driver engagement part in fixed axial engagement with an inner member engagement part.

A method of implanting a two-part screw in a bone, the method comprising:

• assembling a surgical assembly comprising:
• at least one two-part screw, comprising:
• an inner member comprising a distal end, a proximal end;
• and
• an outer member comprising a distal end, a proximal end, a cannula,
• and an outer member interference fit portion,
• wherein the inner member is at least partially disposed within the cannula of the outer member and configured to move axially within the cannula between a deployed position and a retracted position, and
• wherein the outer member interference fit portion is configured to trap the inner member within the cannula of the outer member, wherein the proximal end of the outer member includes a pilot hole configured to receive a punch tool for forming the outer member interference fit portion after the inner member has been loaded into the outer member, wherein in the deployed position a distal portion of the inner member is disposed outside the cannula, wherein in the retracted position at least some of the distal portion is disposed inside the cannula;
• at least one outer member driver comprising:
• an outer driver handle,
• a cannulated outer driver shaft, and
• an outer driver proximal end comprising an outer driver engagement part in fixed rotational engagement with an outer member engagement part;
• and
• at least one inner member driver comprising:
• an inner driver handle proximal to the outer driver handle,
• an inner driver shaft within the cannulated outer driver shaft, and
• an inner driver proximal end comprising an inner driver engagement part in fixed axial engagement an inner member engagement part;
• applying an axial force to the inner driver handle to advance the inner member into the bone and advance the surgical assembly into the bone;
• applying a rotational force to the outer driver handle to advance the outer member into the bone and advance the outer member over the inner member;
• locking relative rotational movement of the inner member and the outer member by advancing the outer member into the bone until the inner member engages the outer member interference fit portion;
• removing the at least one inner member driver;
• and
• removing the at least one outer member driver.

A surgical assembly kit comprising:

• at least one two-part screw, comprising:
• an inner member comprising a distal end, a proximal end;
• and
• an outer member comprising a distal end, a proximal end, a cannula, and an outer member interference fit portion,
• wherein the inner member is at least partially disposed within the cannula of the outer member and configured to move axially within the cannula between a deployed position and a retracted position, and
• wherein the outer member interference fit portion is configured to trap the inner member within the cannula of the outer member, wherein the proximal end of the outer member includes a pilot hole configured to receive a punch tool for forming the outer member interference fit portion after the inner member has been loaded into the outer member, wherein in the deployed position a distal portion of the inner member is disposed outside the cannula, wherein in the retracted position at least some of the distal portion is disposed inside the cannula;
• at least one inner member driver comprising:
• an inner driver handle,
• an inner driver shaft, and
• an inner driver proximal end comprising an inner driver engagement part configured to engage an inner member engagement part;
• and
• at least one outer member driver comprising:
• an outer driver handle,
• a cannulated outer driver shaft configured to accept the inner driver shaft, and
• an outer driver proximal end comprising an outer driver engagement part configured to engage an outer member engagement part,
• wherein the outer driver handle is configured to be distal to the inner driver handle.