Method and apparatus for inserting and countersinking a modular screw

An instrument to insert a modular screw into a substrate while allowing for removal of the instrument without disturbing the inserted modular screw. The instrument generally includes a first member that is cannulated. A second member of the instrument engages the modular screw shank. A compression force and locking engagement is created between the modular screw and the instrument which holds the modular screw in the instrument during the insertion of the modular screw. After the modular screw shank has been inserted, the second member of the instrument is removed from the first member which allows for the first member of the instrument to rotate freely around the modular screw. In this way, the instrument can be removed from the modular screw without disturbing the modular screw after implantation.

FIELD OF THE INVENTION

The present invention relates to an instrument to insert a modular screw shank into a structure, and more particularly, to a countersinking instrument that can insert a modular screw shank and be removed without disturbing the inserted modular screw shank.

BACKGROUND OF THE INVENTION

It is generally known in the art to interconnect at least two different elements with a member such as a screw. For example, in medical procedures, a bone plate may be affixed to a fractured or broken bone using a screw which passes through the bone plate and thoroughly engages the substrate bone. In other medical applications, two portions, of fractured bone may be joined together by a screw. The screw generally includes a head portion, which allows a tool to engage the screw, and an integral shank portion, which has threads for engaging the substrate bone. The tool to engage the head portion may be any appropriate tool which can apply enough torque between the tool and the screw to thread it into the substrate.

With these commonly known systems, however, the entire screw is formed of a single material. This single material may be a material that is bio-absorbable. Therefore, after a period of time, the screw will resorb into the body into which it is implanted. Other screws may be formed of materials which are not bio-resorbable and remain permanently affixed within the body into which they are implanted. A bio-resorbable screw, after it has been resorbed, applies no fixation force to an implanted portion or to the bone into which it was implanted. On the other hand, a screw which is formed of a non-resorbable material remains permanently within the bone and may protrude undesirably from the bone into which it is affixed.

It is also known to provide a cannulated screw which includes a cannula through the screw. The cannula in the screw allows it to be guided into the implantation site using a guide system such as a wire. Therefore, the physician, while implanting the screw, does not need to have a clear view of the entire surgical area, but rather may use the wire to guide the screw into place.

It has become desirable to provide a screw which is modular. A modular screw may include a bio-resorbable and a non-bioresorbable portion to be implanted at a single location. Therefore, a non-resorbable portion may always be permanently affixed within the body to provide a fixation in the substrate. While the resorbable portion is resorbed into the body, thereby removing any protrusions which may not be desirable.

The insertion of such a modular screw can be particularly difficult. In particular, a modular screw may include a modular head which is inserted separate from the modular shank portion of the modular screw. Therefore, an instrument to engage such a modular screw requires unique and new characteristics to engage and insert the modular screw. If the modular screw is large enough, protrusions or indentations may be included on the modular screw which may be engaged by an instrument to insert and remove the modular screw. If the modular screw is particularly small, however, there may not be space to form such indentations or protrusions. Therefore, it is desirable to provide an instrument which can insert and remove a modular screw which is small and does not allow for the inclusion of protrusions or detents to be engaged by the instrument.

SUMMARY OF THE INVENTION

The present invention generally provides an instrument to insert a modular screw into a substrate while allowing for removal of the instrument without disturbing the inserted modular screw. The instrument generally includes a first member that is cannulated to receive internally the modular screw. A second member of the instrument engages the modular screw creating a compression force and a locking engagement between the modular screw shank and the instrument, which holds the modular screw in the instrument during the insertion of the modular screw. After the modular screw has been inserted, the second member of the instrument may be removed or loosened from the first member allowing the first member of the instrument to rotate freely around the modular screw. In this way, the instrument can be removed from the modular screw without disturbing the modular screw after implantation.

A first embodiment of the present invention includes an instrument for inserting and removing a modular screw. The instrument includes a cannulated holding member to hold the modular screw. An engagement member movable between an engaged position and a non-engaged position. An engaging system is adapted to direct the engagement member between the engaged position and the non-engaged position. When the engagement member is in the engaged position the modular screw is locked relative the holding member.

A second embodiment of the present invention includes an instrument for inserting a shank of a modular screw into a substrate and countersinking the same. The instrument includes a holding member comprising a first member, that is cannulated, having a first end and a second end. The cannulated member has a first engagement section adjacent the first end and a second engagement section adjacent its second end. An engagement member is movable between an engaged position and a non-engaged position within the cannula of the holding member. The first engagement section is adapted to engage the shank. The second engagement section selectively engages the engagement member. When the engagement member is in the engaged position in the second engagement section, the engaging member holds the shank in a single position relative to the holding member.

A third embodiment includes a system to insert a modular screw a distance into a structure such that the modular screw does not move out of the structure when the system is removed. The system includes a holding member including a first cannulated member having a first end and a second end. An engagement member including a second cannulated member has a first end and a second end, wherein the first end of the engagement member is adapted to be received in the second end of the holding member. A connection mechanism selectively interconnects the holding member and the engagement member. The first end of the holding member is adapted to engage the shank in the cannula. The engagement member engages the shank through the holding member to hold the shank in a single position relative to the holding member. The engagement member, when engaging the shank, is also fixed relative to the holding member.

The present invention presents a new method of manipulating a modular screw shank in relation to a substrate with an instrument. The method includes providing an instrument including a holding member and an engagement member. A modular screw is inserted into a shank end of the holding member. The modular screw is engaged with the engagement member between the holding member and the engaging member such that the modular screw shank is selectively fixed relative to the holding member. A force is transferred to the modular screw via the provided instrument.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Although the following description describes inserting a modular screw into a bone it may also be used for other procedures, for example the tool may be used to insert a modular screw through a plate.

With reference toFIGS. 1aand1b, a modular screw30is illustrated. The modular screw30includes a shank portion or a modular shank33that has a shank engaging end33a. At a first end of the screw shank33, is a set of head engaging threads34. Substrate engaging threads36are on an end opposite the head engaging threads34. It will be understood that a substrate, such as a bone substrate is often engaged by the substrate engaging threads36. Furthermore, the substrate engaging threads36may be self-tapping and self-drilling. Therefore, the substrate engaging threads36do not require a previously drilled and tapped hole. A smooth area38separates the head engaging threads34and the substrate engaging threads36. The smooth area38, however, is not necessary. It will be understood, therefore, that the head engaging threads34may extend along the smooth area38and meet the substrate engaging threads36. Otherwise, the smooth area38may simply be eliminated and the entire screw shank33will simply include head engaging threads34or substrate engaging threads36.

The modular screw30also includes a modular head or head portion40. The head portion40includes a drive section42and a head section44. Within the head section44are internal head threads46which are adapted to engage the head engaging threads34on the screw shank33. In this way, once the modular screw30has been inserted into a substrate, the internal head threads46engage the head engaging threads34for affixing the head section44to the shank33. After this, the drive section42may be cut off of the head portion40through any appropriate means. The head portion40may be formed of a polymer material. The polymer material may be a resorbable material so that after a time the head section44is absorbed into the body. For greater detail on a modular screw, U.S. patent application Ser. No. 09/853,425, entitled “Bone Screw Having Bioresorbable Proximal Shaft Portion” is incorporated herein by reference.

In a first embodiment of the present invention illustrated inFIG. 2, a modular screw inserter instrument or tool100includes a holding or countersinking section102which may be engaged with either an inserting engagement member104, also known as an inserting locking section, or a removing engagement member106, also known as a removing locking section. The holding member102is a cannulated member defining a cannula108extending along a central axis A around which also defines a center of the holding member102. The cannula108has a first cannula section110and a second or shank cannula section112. The shank cannula section112has internal shank engaging threads116which are adapted to substantially mate with the external head engaging threads34of the screw shank33. Formed externally of the shank cannula section112are countersinking flutes118. The countersinking flutes118countersink an area for the head40in a substrate during implantation. In the first cannula section110, extending along axis A and away from the shank cannula section112, is a second set of threads which are inserting threads120and a third set of threads which are removing threads122. The removing threads122are formed axially a distance from the inserting threads120.

The inserting threads120are right hand or clockwise threads which generally are for inserting. That is, the inserting threads120are formed in a right hand manner in the first cannula section110so as to engage a member having external right hand threads. This allows the holding member102to be turned in a clockwise or right hand direction once engaged by the proper member, as described herein. The removing threads122are formed in a left hand manner. The removing threads122engage external left hand threads allowing the holding member102to be turned in a counterclockwise or left hand direction, also described herein. The major diameter Y, or the diameter from a thread peak to a thread peak across from it, of the inserting threads120is smaller than the minor diameter X, the diameter from a thread valley to a thread valley across from it of the removing threads122. This allows the inserting threads120and the removing threads122to be substantially independent of one another and only mate with a member which has mating threads for one particular set of threads formed in the first cannula section110. In particular and described further herein, external threads that engage the inserting threads120may pass through the removing threads without engaging the removing threads122.

The inserting engagement member104is formed cylindrically and extends along an axis B. A threaded section124includes external inserting member threads126which mate substantially with the inserting threads120in the first cannula section110. In this way, the inserting engagement member104be threaded into the first cannula section110by mating the inserting member threads126, of the threaded section124, with the inserting threads120in the first cannula section110. This is so because the major diameter of the inserting member threads126is less than the minor diameter of the removing threads122. Therefore, the inserting member threads126pass through the removing threads122.

Because the inserting threads120are right hand threads, the inserting member threads126are right hand threads. Therefore, as the inserting engagement member104is tightened into the first cannula section110, the inserting engagement member104is turned to the right or clockwise. Once the inserting engagement member104is locked in placed, as described herein, the tool100can then be turned in a clockwise direction. This also turns the screw shank33in a clockwise direction driving the screw shank33into a substrate, as described herein.

Extending from the threaded section124is a manipulation section132. The manipulation section132includes a first manual manipulation section134. The manual manipulation section134may be knurled or otherwise textured to allow for an easy grip of a hand onto the inserting engagement member104. Extending from the manual manipulation section134is an automatic or tool manipulation section136. The tool manipulation section136includes any appropriate design that allows it to be easily inserted into an automatic tool, such as a drill. In this way, the inserting engagement member104can be inserted into the holding member102using either manual manipulation or automatic manipulation. Additionally, once the engagement member104or106has been inserted into the holding member102, the automatic manipulation section136is used to affix it to a drill to allow for a greater torque and force during the insertion of the screw shank33.

Extending from an end opposite the manipulation section132, but still along axis B, is the shank engagement nose138. The shank engagement nose138has an outer diameter which is substantially equal to the internal diameter defined by the shank engaging threads116in the shank cannula section112. The shank engagement nose138includes a leading edge140which is designed to mate with the engaging end33aof the screw shank33. The diameter of the shank engagement nose138may be any appropriate size to engage the engaging end33aand not necessarily equal to the diameter of the threads. The inserting engagement member104may also define an inserting member cannula142.

The removing engagement member106includes a releasing threaded section144including external releasing threads146. The releasing threads146are designed to substantially mate with the removing threads122, formed in the first cannula section110. Because the removing threads122are left hand threads, the removing engagement member106is rotated in a counterclockwise direction to insert the removing engagement member106into the holding member102. In this manner, when a leading edge149of a screw shank engagement nose148engages the engagement end33aof the screw shank33, the instrument100may be used to remove the screw shank33after it has been inserted. The removing engagement member106also includes a removing cannula150. It will be understood that the removing engagement member106will also have a manipulation portion132′, similar to the manipulation portion132of the inserting engagement member104, to manipulate the removing engagement member106, wherein similar portions are denoted with the same numerals augmented by a prime.

With reference toFIGS. 3a–3b, the instrument100is illustrated assembled. The inserting engagement member104interacts with the inserting threads120while the shank33, interacts with the internal shank engaging threads116to form an engagement system. The inserting engagement member104has been fully inserted into the holding member102. It will be understood, however, the following process also generally applies if the removing engagement member106is inserted in the holding member102, as specifically illustrated inFIG. 3b. The screw shank33is first inserted into the holding member102, by engaging the head engaging threads34of screw shank33with internal shank engaging threads116of the holding member102to define a first engagement section. The inserting engagement member104is then inserted into the cannula108of the holding member102to engage the screw shank33which defines a second engagement section. The leading edge140of the shank engagement nose138presses against the engaging end33aof the screw shank33and holds the screw shank33in place with a friction force. The two engagement sections create this engagement system.

The force of the inserting engagement member104pushes against the engaging end33aof the screw shank33to hold it in place. When the screw shank33is so held it is locked. When locked the instrument100can be operated to insert the screw shank33into a bone or other substrate. The pressure of the shank engagement nose138not only holds the screw shank33in place, but holds the inserting engagement member104in place relative to the holding member102. This allows for the inserting engagement member104to be the impetus of all the force applied to the screw shank33and the countersink flutes118. The inserting engagement member104, when the shank engagement nose138engages the screw shank33, is locked in place relative to the holding member102.

Once the instrument100is fully assembled, by placing the screw shank33in the shank engaging threads116and then locking the screw shank33in place with the inserting engagement member104, the screw shank33may be inserted into a bone200. With reference toFIGS. 4 through 7b, the method of using the tool100to insert a screw shank33into the bone200is more fully described. After locating and properly preparing the bone200, which has a malady such as a crack202, the insertion of the screw shank33may begin. It will be understood that the bone200is generally surrounded by other soft tissue masses which are not illustrated for clarity.

The screw shank33is inserted into the holding member102such that the head engaging threads34of the screw shank33engage the internal shank engaging threads116of the holding member102. The inserting engagement member104is then threaded into the holding member102, through the interaction of the inserting member threads126and the inserting threads120. The leading edge140of the shank engagement nose138abuts the screw shank33. After the locking force is created between the leading edge140of the shank engagement nose138and the engaging end33aof the shank33, the screw shank33is locked in place relative to the holding member102. The locking force also locks the inserting engagement member104relative to the holding member102.

It will be understood that the portion of the screw shank33extending from the holding member102may be any appropriate length. In particular, the length of the screw shank33extending from the holding member102is sufficient to engage the substrate bone200in any appropriate manner. Such as illustrated where the screw shank33extends into the bone200to engage the bone200on both sides of the crack202. The portion of the screw shank33within the holding member102is not threaded into the bone200with the tool100. The screw shank engagement nose138may also be any appropriate length so that it will engage the screw shank33while allowing an appropriate amount of the screw shank33to extend from the holding member102.

The screw shank33may be self drilling and self tapping screw, so that it acts as a drill bit and tap bit. Therefore, once the inserting engagement member104has been locked onto the screw shank33, the entire tool100is engaged in any other appropriate instrument or tool to provide the power and torque to drill the screw shank33into the bone200. As the tool100is inserted further into the bone200, the countersinking flutes118also form a countersink area204in the bone200. As specifically illustrated inFIG. 6, when the tool100is removed, the screw shank33is inserted into the bone200and a countersink area204remains.

With reference toFIG. 5, once the screw shank33has been inserted a sufficient distance into the bone200, the screw shank33engages both sides of the crack202to hold the bone200in the proper orientation to allow healing. Once the screw shank33has been inserted the appropriate distance, the inserting engagement member104may be removed or loosened from the holding member102by turning the inserting engagement member104in a counter clockwise direction. This leaves the holding member102in position. Once the inserting engagement member104has been removed or loosened, the holding member102may rotate substantially freely about the screw shank33. Although the remaining discussion refers to removing the engagement members, this is only for clarity and simply loosening them provides equal advantages. The forces between the screw shank33and the bone200are now greater, after removing inserting engagement member104, than the forces now between the screw shank33and the shank engaging threads116. Therefore, the holding member102is removed from the screw shank33by unscrewing the holding member102. Simply unscrewing the holding member102leaves only the screw shank33in place in the bone200.

As shown particularly inFIG. 6, the screw shank33extends into the countersink area204the distance that the screw shank33was inside the holding member102. The screw shank33, however, is left unmoved from its inserted position due to the fact that the inserting engagement member104had been removed from a holding member102. Removing the inserting engagement member104from the holding member102substantially eliminates the locking force between the shank33and the shank engaging threads116. Removing the locking force unlocks the tool100allowing the holding member102to be easily removed from the screw shank33. Furthermore, this leaves the screw shank33in place and appropriately placed in the countersink area204and the bone200.

After the holding member102has been removed, any appropriate modular screw head40may be affixed to the modular screw shank33. One appropriate modular screw head is disclosed in U.S. application Ser. No. 09/853,425 entitled “Bone Screw Having Bioresorbable Proximal Shaft Portion” incorporated herein by reference. The modular screw head section44fits within the countersink area204produced in the bone200by the countersinking flutes118. This allows for a substantially flush fit of the head section44with the bone200to aid in healing. In addition, the head section44may be formed of a resorbable material so that after a period of time it will be resorbed into the body. Bone200may then regrow into the countersink area204so that no foreign or implant material is actually exterior of the bone200. In this way irritation between the implant and the soft tissue, which will grow over the bone200, is substantially reduced.

If at a certain point the screw shank33is desired to be removed from the bone200, such as to reset or move the screw shank33, the removing engagement member106is employed. If the head section44is present, it is first removed so that the shank engaging threads116may engage the head engaging threads34of the screw shank33by threading the holding member102onto the screw shank33, defining a first engagement section. After this has occurred, the removing engagement member106is threaded into the holding member102such that the releasing threads146engage the removing threads122and form a second engagement section. These two engagement sections define an engagement system of the tool100.

Because the removing threads122are formed in a left hand manner, the removing engagement member106is rotated in a counter clockwise direction to mate the releasing threads146with the removing threads122. As the removing engagement member106is threaded into the holding member102, the leading end149of the shank engagement nose148engages the end33aof the screw shank33. As before, a locking force is created by pressing a leading end149against the engaging end33aof the screw shank33. Once the locking force has been created, the tool100may be rotated in a counter clockwise direction to release and remove the screw shank33.

Once the screw shank33is removed or released an appropriate amount from the bone200, the removing engagement member106is unscrewed from the holding member102by rotating the removing engagement member106in a clockwise direction. This removes or substantially eliminates the locking force so that the screw shank33may be rotated freely within the holding member102. In this way, the screw shank33may be removed from the bone200after implantation into the bone200.

It will also be understood that the inserting engagement member104and the removing engagement member106may be cannulated to provide a passage therethrough. The screw shank33may also be cannulated so that an internal passage is formed throughout the entire tool100after it is assembled. In this way, a guide wire or other instrument, inserted through the screw shank33and through the tool100, may be used as a guide to guide the screw shank33into place.

It will also be understood that the engagement system need not be two separate and distinct portions. In particular, the shank engagement nose138,148may include external threads which have a same diameter and pitch as the head engaging threads34on the modular screw shank33. In this circumstance, only one set of internal threads would be required in the holding member102to engage both the modular screw33and the engagement members104or106. Therefore, a modification, such as this, does not stray from the scope of the present invention.

With reference toFIGS. 8 and 9, a second embodiment of the modular screw inserter instrument or tool300includes a holding member302and an engaging member304. The holding member302includes a first end306, which has countersinking flutes307defined on the exterior thereof. The holding member302is formed along an axis C and includes a cannula308. The cannula308includes a first cannula section310and a second cannula section312. The second cannula section312has an internal diameter which includes shank engaging threads314. The shank engaging threads314engage the head engaging threads34of a modular screw shank33. In this way, the screw shank33may be inserted into the second cannula section312for insertion into a substrate.

Formed on an end of the holding member302, opposite the first end306is a track318. The track318defines a bore which includes a central peaked section320, a clockwise depression322, and a counter-clockwise depression324. The track318generally defines a C-shape. As described herein, however, the precise shape of the track318may be any appropriate shape to provide the mechanism of driving the engagement member304into engagement with the screw shank33.

The engagement member304includes a body portion326having a screw shank engagement nose328extending from one end and a tool engaging section330extending from an end opposite the shank engagement nose328. Formed axially along the engagement member304, through the nose328, the body326, and the tool engaging section330, is a cannula332. A bore334is formed in the body section326of the engagement member304. The bore334receives a pin336. The pin336includes a bore338which, when inserted into the bore334, is substantially axial with the cannula332formed in the engagement member304. This is so that the pin336does not obstruct the cannula332of the engagement member304.

With reference toFIG. 9, the tool300is assembled and includes the body portion326substantially within the first cannula section310of the holding member302. Also, when assembled the shank engagement nose328is received substantially in the second cannula section312. Once the engagement member304is received within the holding member302, the pin336is inserted through the track318and then into the bore334, of the engagement member304which defines the second engagement section. It will be understood, however, that the pin336may also be placed on a biasing spring within the bore334. With a biasing spring, the pin336would spring up through the track318rather than being inserted through the track318. Also, if a biasing spring were used, the track318would not need to be a bore, but rather a depression on the inside of the holding member302. In either case once the pin336is inserted into the track318, the tool300is preferably designed to not be disassembled, as described in the first embodiment. Nevertheless, the engagement member304is able to move substantially freely within the cannula108of the holding member302.

The operation of the tool300, according to the second embodiment, will now be more clearly described. Once the tool300is fully assembled, a screw shank33is threaded into the shank engaging threads314defining the second engagement section. This is performed when the engagement member304is in a non-engagement position. The non-engagement position is achieved when the pin336is substantially axial with the peak320of the track318. Once the screw shank33is inserted into the shank engaging threads314, such that the screw shank33substantially meets the shank engagement nose138of the engagement member304, the tool engaging section330is engaged in a tool.

To insert the screw shank33, the tool300is turned in a clockwise direction. As the tool300is turned in a clockwise direction, the pin336rides in the track318to engage the clockwise depression322. The engagement in the clockwise depression322forces the engagement member304onto the end of the screw shank33. This substantially locks the screw shank33in place within the holding member302. Therefore, the screw shank33may be driven into a substrate, such as a bone, as described in relation to the first embodiment.

Once the screw shank33has been inserted to the appropriate depth and the countersink has been cut with the countersink flutes307, the engagement member304is moved to the non-engaging position. That is, the engagement member304is rotated, without rotating the holding member302, so that the pin336is substantially axial with the peak320. At this point, the shank engagement nose328no longer engages the screw shank33. This unlocks the engagement member304from the screw shank33so that the holding member302may be turned freely relative to the screw shank33. In this way, the tool300may be removed from the screw shank33without moving the screw shank33after it has been inserted into a substrate.

According to the second embodiment of the tool300, a separate engagement member is not needed to remove a screw shank33from a bone. Once a screw shank33is inserted into a bone, the holding member302is simply threaded over the head engaging threads34with the shank engaging threads314. Once threaded over the screw shank33, such that the shank engagement nose328has engaged the screw shank33, the tool engaging section330is engaged in a power tool. To remove the screw shank33, the tool300is turned in the counter-clockwise direction. Now, the pin336travels in the track318to engage the counter-clockwise depression324. The shank engagement nose328, by this, is moved into an engaged position and engages the screw shank33. In the engaged position, the engagement member304holds the screw shank33in a substantially locked position when the pin336is in the counter-clockwise depression324. In this way, the screw shank33may be removed from the substrate since the screw shank33is locked in position. Then, once the screw shank33has been removed, the engagement member304is simply moved to the non-engaging position, that is when the pin is substantially axial with the peak320, and the screw shank33may spin freely and removed from the holding member302.

It is understood that the engaging position provides the locking force between the engagement member304and the screw shank33. According to the second embodiment, rather than screwing the engagement member304into the holding member302, the interaction between the pin336and the track318provides the locking force. Likewise, the non-engagement position substantially removes the locking force and unlocks the tool300.

The track318may be any appropriate shape to provide the same mechanism as the C-shape of the illustrated track318. A C-shape is simply one example of an appropriate shape. A track simply needs to be provided to allow the pin336to force the engagement member304against the shank33.

The above embodiments are merely examples of tools for inserting and removing a modular screw shank from a substrate such as a bone. It will be understood that other appropriate designs may be used to form a means for inserting and removing a modular screw. In particular, designs similar to retractable pens may be used. In a first position, the retractable pen forces the point out of the body. Similarly, the mechanism, in a first position, forces an internal engagement member towards a modular screw shank to provide a compression or locking force between the modular screw shank and the holding member. The locking force locks the engagement member relative to the screw shank and the holding member. In the locked position, the entire tool may be rotated to either insert or remove the modular screw shank.

The engagement member then also has a non-engaging position, such as when a retractable pen is retracted to retract the point into the body, so that the locking force is removed. When the locking force is removed, the holding member may be removed from the screw shank or the screw shank removed from the holding member. Therefore, it is understood that the above embodiments are simply exemplary of embodiments which may be designed to provide a tool to insert and remove a modular screw shank.

The tool100,300preferably has a member that allows the release of a locking force between the screw shank, which is insertable into a substrate, and the tool itself, so that the tool may be removed from the screw shank without moving the screw shank relative the substrate. In particular, if the forces between the tool and the screw shank were not relieved before removing the tool from the screw shank, then the screw shank would be loosened by removing the tool. In providing an apparatus that allows the substantial elimination of the forces between the tool and the screw shank, the tool may be removed from the screw shank without moving the screw shank once it has been inserted into a substrate. Therefore, a precise and predetermined depth of insertion of the screw shank into a substrate can be achieved. Furthermore, this can be achieved without providing on the screw shank any other engagement mechanism beside external threads. That being that the locking force created between the screw shank and the tool, particularly the internal threads of the holding member and the engagement member, provide the resistance necessary to torque the screw into a substrate. These forces, however, are easily removed by removing the engagement member from the holding member so that the holding member may then be removed from the screw shank without upsetting the placement of the screw shank. Furthermore, this apparatus allows for a headless screw shank to be removed from a substrate after insertion by recreating the locking forces by placing the engagement member within the holding member.