(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`1111111111111111111111111111111111111111111111111111111111111111111111111111111111111
`
`(43) International Publication Date
`31 July 2003 (31.07.2003)
`
`PCT
`
`(10) International Publication Number
`WO 03/061495 A2
`
`(51) International Patent Classification7:
`
`A61B 17/74
`
`(21) International Application Number:
`
`PCT/IL03/00052
`
`(74) Agents: FENSTER, Paul et al.; Fenster & Company,
`Intellectual Property 2002 Ltd., P.O. Box 10256, 49002
`Petach Tikva (IL).
`
`(22) International Filing Date: 22 January 2003 (22.01.2003)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`147783
`
`23 January 2002 (23.01.2002)
`
`IL
`
`(jor all designated States except US):
`(71) Applicant
`DISC-O-TECH MEDICAL TECHNOLOGIES, LTD.
`[IL/IL]; Hasadnaot Street, 46728 Herzelia (IL).
`
`(72) Inventors; and
`(75) Inventors/Applicants (jor US only):
`SHAVIT, Ro(cid:173)
`nen [IL/IL]; Weinshal Street 5, 69413 Tel-Aviv (IL).
`GLOBERMAN, Oren [IL/IL]; Derech Haganin Street
`30, 46910 Kfar-Shmaryahu (IL). BEYAR, Mordechay
`[IL/IL]; Haeshkolit Street 7, 30600 Caesarea (IL).
`
`iiiiiiii
`
`(81) Designated States (national): AE, AG, AL, AM, AT, AU,
`AZ, BA, BB, BG, BR, BY, BZ, CA, CH, CN, CO, CR, CU,
`CZ, DE, DK, DM, DZ, EC, EE, ES, Fl, GB, GD, GE, GH,
`GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC,
`LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW,
`MX, MZ, NO, NZ, OM, PH, PL, PT, RO, RU, SC, SD, SE,
`SG, SK, SL, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ,
`VC, VN, YU, ZA, ZM, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW),
`Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European patent (AT, BE, BG, CH, CY, CZ, DE, DK, EE,
`ES, Fl, FR, GB, GR, HU, IE, IT, LU, MC, NL, PT, SE, SI,
`SK, TR), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, GN,
`GQ, GW, ML, MR, NE, SN, TD, TG).
`
`Declaration under Rule 4.17:
`ofinventorship (Rule 4.17(iv))for US only
`
`[Continued on next page]
`
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`(54) Title: LOCKING MECHANISM FOR INTRAMEDULLARY NAILS
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`~ (57) Abstract: Intramedullary nail apparatus comprising: an intramedullary nail having an axis, a proximal end, a distal end, a first
`hole going through the nail at an angle to the axis, and a second hole going through said nail at the same or a different angle to the
`0 axis, with the second hole closer to the proximal end than the first hole; a first screw which goes through the first hole; a second screw
`> which goes through the second hole; and a locking mechanism, accessible from the proximal end of the nail, operative to selectively
`~ lock in place the first screw.
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`1111111111111111111111111111111111111111111111111111111111111111111111111111111111111
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`Published:
`For two-letter codes and other abbreviations, refer to the "Guid-
`without international search report and to be republished ance Notes on Codes and Abbreviations" appearing at the begin-
`upon receipt of that report
`ning of each regular issue of the PCT Gazette.
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`LOCKING MECHANISM FOR INTRAMEDULLARY NAILS
`FIELD OF THE INVENTION
`The present invention relates to the field of surgical nails used to repair bone
`fractures, in particular intramedullary nails used for fractures of the proximal femur.
`BACKGROUND OF THE INVENTION
`Intramedullary nails, which are designed to repair fractures of the proximal femur,
`for example reconstructive nails or gamma nails, include a nail which is inserted into the
`medullar channel, and at least one lag screw, going through the nail at an angle, and
`through the neck of the femur, which is supposed to hold the neck of the femur and
`trochanter in place. In some designs there are two screws: a larger screw, and a smaller
`screw which goes through the nail closer to the proximal end than the larger screw.
`Depending on the type of fracture, it may be desirable to limit the motion of the screw or
`screws relative to the nail. The lack of a mechanism to do this limits the usefulness of
`these nails. For example, it was reported by Florin et al [N. Florin, T. Roessler and K.
`15 Westermann, "Possible complications of internal fixation using the Gamma Nail," in The
`Gamma Locking Nail: Ten Years Results and Surgical Experience, R. H. Gahr, K.-S.
`Leung, M.P. Rosenwasser and W. Roth, eds., Einhom-Presse Verlag, Germany, p. 244]
`that the screws sometimes migrate after surgery, damaging the hip joint or allowing the
`trochanter to collapse.
`In existing nails which use a single lag screw, there may be a small set screw, set
`into the proximal end of the nail by the surgeon, which can be tightened to keep the lag
`screw from moving, or to limit its motion, once the nail is in place. (Often it is not desired
`to hold the lag screw rigidly in place, but only to limit the range of its motion with respect
`to the nail, since it is believed that the bone will heal better if it is allowed to move and
`bear some of the load. "Locking" the screw as used here does not necessarily mean
`preventing it from moving at all, but it may simply mean limiting its motion.) In nails
`which use two lag screws, it is not possible to lock both screws, since the screw that is
`closer to the proximal end of the nail blocks access to the screw that is further from the
`proximal end of the nail. Patent WO 01/39679, for example, describes a nail with two
`screws, a smaller screw closer to the proximal end of the nail and a bigger screw further
`from the proximal end, in which there is no mechanism to lock the screws.
`PCT Publication WO 01/54598 describes an intramedullary nail, the distal portion
`of which is hollow. Once the nail is in place, fluid is forced into the nail under pressure,
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`causing the distal portion to expand radially and lock against the medullar channel. Once
`the bone is healed, the fluid can be drawn out, causing the nail to shrink back radially, so
`that it can be easily removed from the medullar channel. This allows marrow to grow
`back.
`
`SUMMARY OF INVENTION
`An aspect of some embodiments of the invention relates to a nail with two screws
`going through it, one screw closer to the proximal end of the nail than the other screw, and
`a locking mechanism, accessible from the proximal end, which locks the screw that is
`further from the proximal end. Optionally, the locking mechanism does not interfere with
`the screw that is closer to the proximal end. Alternatively, the same locking mechanism,
`or another locking mechanism also accessible from the proximal end of the nail, also locks
`the screw closer to the proximal end. In some embodiments it is possible to lock either
`screw, or both of them, or neither of them, according to the judgment ofthe surgeon.
`An aspect of some embodiments of the invention relates to a nail with at least one
`screw going through it, and a locking mechanism for at least one screw, which locking
`mechanism is an integral part of the nail, and cannot be removed from the nail by mistake.
`An aspect of some embodiments of the invention relates to a nail with at least dne
`screw going through it, and a channel in the nail for injecting liquid into or through the
`nail, in which the channel circumvents the at least one screw. Optionally, the distal portion
`of the nail is hollow, and the channel is used to inject liquid under pressure into the distal
`portion of the nail, causing it to expand radially and lock the nail against the medullar
`channel. Alternatively or additionally, the channel is used to inject some kind of cement to
`hold one or more of the one or more screws in place or to hold the nail in place.
`An aspect of some embodiments of the invention relates to a nail with at least one
`screw, a locking mechanism for locking one or more of the at least one screws, a channel
`for injecting a liquid into or through the nail, and a valve for closing off the channel,
`where the channel is an integral part of the locking mechanism. Optionally, engaging the
`locking mechanism to lock a screw also closes the valve. Alternatively, engaging the
`locking mechanism is independent of closing the valve. Optionally, the distal portion of
`the nail is hollow, and the channel is used to inject liquid under pressure into the distal
`portion of the nail, causing it to expand radially and lock the nail against the medullar
`channel. In this case, closing the valve is necessary in order to keep the liquid under
`pressure. Alternatively or additionally, the channel is used to inject some kind of cement
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`to hold one or more of the one or more screws in place, or to hold the locking mechanism
`in place.
`fu some embodiments of the invention, one or both of the screws are hollow and
`liquid is injected into them under pressure, to cause them to expand and to anchor them in
`the bone, in addition to or instead of using screw threads to anchor them in the bone. Even
`when they are lacking screw threads, these devices are still referred to herein as "screws"
`because they play the same role as the screws in other intramedullary nails. fu these
`embodiments of the invention, the larger screw is also sometimes referred to as a "hip
`peg" and the smaller screw is also sometimes referred to as a ''hip pin."
`There is thus provided, in accordance with an embodiment of the inventions, an
`intramedullary nail apparatus comprising:
`an intramedullary nail having an axis, a proximal end, a distal end, a first hole
`going through the nail at an angle to the axis, and a second hole going through said nail at
`the same or a different angle to the axis, with the second hole closer to the proximal end
`than the frrst hole;
`a first screw which goes through the first hole;
`a second screw which goes through the second hole; and
`a locking mechanism, accessible from the proximal end of the nail, operative to
`selectively lock in place the first screw.
`"'
`fu an embodiment of the invention, the locking mechanism operates to lock into
`place both the first screw and the second screw.
`Optionally, locking the first screw causes the second screw to be locked at the
`same time.
`Alternatively, the locking mechanism selectively locks one of the screws without
`locking the other screw.
`Alternatively, there is a second-screw locking mechanism, accessible from the
`proximal end of the nail, operative to lock in place the second screw, which second-screw
`locking mechanism operates independently of the locking mechanism.
`fu an embodiment of the invention, at least part of the locking mechanism is
`located in the interior ofthe nail between the proximal end and the first hole.
`Optionally, the locking mechanism comprises a linear adapter which moves axially
`when it is rotated, and a stem, adjacent to the linear adapter and closer to the distal end,
`which moves axially without rotating, when the linear adapter moves axially.
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`Optionally, the linear adapter is threaded and screws into an opening at the
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`proximal end ofthe nail.
`Optionally, the stem defines a hole which substantially or completely overlaps the
`second hole of the nail, but is longer than the second hole in the direction of the axis of the
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`Optionally, the stem comprises a tab which extends into the first hole enough to
`reach the first screw when the locking mechanism operates to lock the first screw in place.
`Optionally, the first screw includes a slot, and the tab of the stem fits into the slot
`of the first screw when the locking mechanism operates to lock the first screw in place.
`Alternatively, the second screw defines at least one by-pass hole, and the locking
`mechanism extends through one of the at least one by-pass holes when the locking
`
`mechanism operates to lock in place the first screw.
`Alternatively, the second screw defines a slit, and the locking mechanism extends
`through the slit when the locking mechanism operates to lock in place the first screw.
`Alternatively, the locking mechanism passes to one side of the second screw, when
`the locking mechanism operates to lock in place the first screw.
`Optionally, there is a third screw which passes through the nail at an angle to the
`axis and closer to the proximal end of the nail than the first hole, and the locking
`mechanism passes between the second screw and the third screw when the locking
`
`20 mechanism operates to lock in place the first screw.
`In an embodiment of the invention, there is a channel entrance open to the exterior
`of the nail, at least one channel exit closer to the distal end of the nail than the channel
`entrance is, and a channel adapted for passage of fluid from the channel entrance to the
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`one or more channel exits.
`Optionally, the channel is linked to inject cement to bond in place the second
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`screw.
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`Optionally, the channel is comprised in the locking mechanism.
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`Optionally, the channel circumvents the first hole.
`There is further provided, in accordance with an embodiment of the invention, an
`intramedullary nail apparatus comprising:
`an intramedullary nail with an axis, a proximal end, a distal end, and a first hole
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`going through said nail at an angle to the axis;
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`a first screw which goes through the first hole; and
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`a locking mechanism, operative to lock in place the first screw, and which
`mechanism includes a channel entrance open to the exterior of the nail, at least one
`channel exit closer to the distal end of the nail than the channel entrance is, and a channel
`adapted for passage of fluid from the channel entrance to the one or more channel exits.
`In an embodiment of the invention, the intramedullary nail includes a hollow
`region near the distal end, capable of anchoring the nail in place when fluid is injected into
`said hollow region, and the locking mechanism comprises a valve which operates to seal
`
`the channel.
`Optionally, the locking the locking mechanism closes the valve.
`Alternatively, the locking mechanism operates independently of closing the valve.
`Optionally, the channel is linked to inject fluid into the hollow region.
`Alternatively or additionally, the channel is linked to inject cement to bond in
`place one or both of the nail and the first screw.
`There is further provided, in accordance with an embodiment of the invention, an
`intramedullary nail apparatus comprising:
`an intramedullary nail with an axis, a proximal end, a distal end, and a first hole
`going through said nail at an angle to the axis;
`a first screw which goes through the first hole;
`a channel entrance open to the exterior of the nail, and closer to the proximal end
`of the nail than the first hole is;
`one or more channel exits closer to the distal end of the nail than the first hole is;
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`and
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`a channel adapted for passage of fluid, which channel runs inside the nail from the
`channel entrance to the one or more channel exits, circumventing the first hole.
`In an embodiment of the invention, the intramedullary nail includes a hollow
`region near the distal end, which hollow region expands and anchors the nail in place
`when fluid is injected into said hollow region.
`Optionally, the channel is linked to inject fluid into the hollow region.
`Additionally or alternatively, the channel is linked to inject cement to bond in
`place one or both of the nail and the first screw.
`In an embodiment of the invention, there is a motion limiting element to prevent
`the locking mechanism from separating from the nail.
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`There is further provided, in accordance with an embodiment of the invention, an
`intramedullary nail apparatus comprising:
`an intramedullary nail with an axis, a proximal end, a distal end, and a first hole
`going through said nail at an angle to the axis;
`a first screw which goes through the first hole;
`a locking mechanism, operative to lock in place the first screw; and
`a motion limiting element that prevents the locking mechanism from separating
`from the nail.
`Optionally, at least part ofthe locking mechanism is inside the nail, and the motion
`limiting element comprises:
`a nail-stopping screw;
`a nail-stopping screw hole in the side of the nail going from the outside of the nail
`to the inside ofthe nail; and
`a nail-stopping indentation in the side of the locking mechanism;
`and the nail-stopping screw goes through the nail-stopping screw hole and engages the
`nail-stopping indentation when the motion limiting element operates to prevent the
`locking mechanism from separating from the nail.
`Optionally, the nail-stopping indentation is longer in the direction of the nail axis
`than the width of the portion of the nail-stopping screw than engages in said slot, and the
`20 motion limiting element has at least one mode of operation in which the locking
`mechanism is free to move axially by a given distance but is prevented from separating
`from the nail.
`Optionally, the nail-stopping indentation comprises a slot of limited width in the
`azimuthal direction.
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`the nail-stopping
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`indentation extends around
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`the entire
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`Alternatively,
`circumference of the locking mechanism.
`Optionally, locking the first screw comprises not allowing the first screw to move
`in the direction of its axis.
`Alternatively, locking the first screw comprises allowing the first screw to move
`only a limited distance in the direction of its axis.
`There is further provided, in accordance with an embodiment of the invention, a
`method for installing an intramedullary nail in the proximal femur, comprising:
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`inserting the nail, distal end first, into the medullar channel of the femur from the
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`head of the femur;
`inserting a first screw through a first hole in the nail, through the head of the femur
`and through the trochanter, at an angle to the axis of the nail;
`inserting a second screw through a second hole in the nail, closer to the proximal
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`end of the nail than the fust screw; and
`locking the fust screw in place using a locking mechanism accessible from the
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`proximal end of the nail.
`
`BRlEF DESCRIPTION OF THE DRAWINGS
`
`Exemplary embodiments of the invention are described in the following sections
`with reference to the drawings. The same reference numbers are used for the same or
`similar features on different drawings. Some of the drawings may not be drawn to scale.
`Fig. 1A is a perspective view, and Fig. 1B is a side cross-sectional view, showing a
`nail with holes for inserting two screws, and showing one of the screws inserted into the
`
`nail, according to an exemplary embodiment of the invention;
`Fig. 2 is a perspective view according to the same embodiment as Figs. 1A and
`1B, showing the disassembled parts of the nail itself, without the screws;
`Figs. 3A and 3B show side cross-sectional views of the nail seen from two
`different directions, according to the same embodiment as Figs. 1A and 1B, showing the
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`details of the locking mechanism, valve and channels;
`Fig. 4 is a schematic side view of the nail, showing locking mechanisms for two
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`screws, according to a different embodiment of the invention;
`Figs. SA, SB, and SC are perspective views of the nail according to three different
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`embodiments of the invention; and
`Figs. SD and SE are perspective views of the locking mechanism and the second
`screw (or hip pin), showing mechanisms by which the locking mechanism locks the
`
`second screw, according to two different embodiments of the invention.
`
`DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
`Figs. 1, 2, and 3 illustrate, according to an embodiment of the invention, a nail12
`30 with holes 14 and 16 for inserting two screws, with a locking mechanism 22, accessible
`from the proximal end of the nail, which locks in place the larger screw 10, which is
`further away from the proximal end, without interfering with the smaller screw, which is
`closer to the proximal end. The larger screw is also called a hip peg and the smaller screw
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`is also called a hip pin. In other embodiments of the invention, the two screws are the
`same size, or the larger screw is closer to the proximal end.
`Fig. 1A is an external view of the proximal portion of nail 12, with smaller hole
`14, closer to the proximal end, and larger hole 16 further from the proximal end. Hip peg
`10 is shown inserted into hole 16. No hip pin is shown in hole 14, for clarity. A cross(cid:173)
`sectional side view of the same embodiment is shown in Fig. 1B, in order to show how the
`hip peg is locked. The hip peg has a slot 18, and there is a tab 20, at the end of locking
`mechanism 22, which fits into slot 18, preventing hip peg 10 from coming out of hole 16.
`(The rest oflocking mechanism 22 is not shown in Fig. 1B, but is shown in Figs. 2 and 3.)
`If slot 18 is 20 mm longer, for example, than tab 20, in a direction along the axis of the hip
`peg, then the hip peg is able to move back and forth along its axis a distance of 20 mm,
`even when it is locked. Optionally, slot 18 is also wider azimuthally than tab 20, so that
`the hip peg is free to rotate by a limited angle when tab 20 is inserted into slot 18, in
`addition to being free to move a limited distance along its axis. Alternatively or
`additionally, slot 18 is spiral-shaped, so that the hip peg is free to move along its axis by a
`limited amount, only if it also rotates at the same time. Optionally, there is a second slot in
`hip peg 10, shorter than slot 18, so that hip peg 10 would not be free to move at all when
`tab 20 is inserted into the second slot. Then hip peg 10 can either be locked completely,
`or partially locked with freedom to move a limited amount. Optionally, the second slot is
`inside slot 18. Alternatively, the second slot is separate from slot 18. Optionally, the
`inside of slot 18, or another slot, is lined with a resilient material. Then, when tab 20 is
`inserted into that slot, hip peg 10 can move a limited amount, but there is a spring force
`resisting its motion. Such an arrangement has the advantage that the stress is not entirely
`born by the nail, or entirely born by the bone, but is distributed between the nail and the
`bone, which may promote optimal healing of the bone. Alternatively or additionally, such
`a spring force can be produced by making the nail or locking mechanism out of a
`compliant material.
`In the embodiment of the invention shown in Figs. 1A and 1B, hip peg 10 has a
`hollow region 23 at its end, which expands radially, anchoring it in place in the bone,
`30 when it is filled with liquid under pressure. Alternatively or additionally, screw threads or
`any other anchoring mechanism is used to anchor hip peg 10 in the bone.
`Fig. 2 shows nail 12 with the disassembled parts of locking mechanism 22, in
`order to illustrate how the locking mechanism is able to lock the hip peg without
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`interfering with the hip pin. Locking mechanism 22 comprises a linear adapter 24 and a
`stem 26. There is an opening 27 at the proximal end of the nail. Adapter 24 has threads 38
`which match threads inside opening 27. When adapter 24 is inserted into opening 27 and
`the threads are engaged, turning adapter 24 with a screw-driver makes adapter 24 move
`axially with respect to the nail. Adapter 24 connects to stem 26, using coupling
`mechanism 36. The coupling mechanism allows adapter 24 to rotate freely with respect to
`stem 26 while it is coupled. In particular, the coupling mechanism allows adapter 24 to
`push or pull stem 26 axially, without requiring stem 26 to rotate, when adapter 24 is
`turned by a tool such as a screw-driver and moves axially with respect to the nail. As will
`be explained, the lack of rotation of stem 26 makes it possible for the locking mechanism
`not to interfere with the hip pin. In this embodiment, coupling mechanism 36 does not
`allow adapter 24 to become disconnected from stem 26 as long as they remain inside the
`nail, since the narrowness of the opening in the nail keeps adapter 24 and stem 26 from
`moving very far transversely to the axis of the nail. Adapter 24 and stem 26 are coupled
`together before they are inserted into the nail. Adapter 24 optionally has a hex nut 42 at its
`end, which allows adapter 24 to be turned by a socket screwdriver inserted into opening
`27. Alternatively, another mechanism known to the art is used to tum adapter 24 while it
`is inside the nail.
`Locking mechanism 22 is designed to avoid interfering with the hip pin. This is
`accomplished by means of a hole 32 in stem 26. Hole 32 is longer than hole 14 in the
`direction ofthe axis of the nail. When locking mechanism 22 is operating to lock hip peg
`10, hole 32 overlaps hole 14, and it is possible to insert the hip pin through hole 14 and
`hole 32. The fact that hole 32 is longer than hole 14 allows the two holes to remain
`overlapping axially when stem 26 moves a limited distance axially. Optionally, hole 32 is
`long enough so that it does not interfere with the hip pin, when stem 26 moves axially
`from a position where hip peg 10 is completely unlocked, to a position where hip peg 10
`is fully locked. This may be seen in Fig. 3A, which shows a cross-sectional view of
`locking mechanism 22 assembled inside the nail.
`Alternatively, hole 32 has a tab inside it, similar to tab 20, which engages in a slot
`in the hip pin, similar to slot 18 in the hip peg, and locks the hip pin in place when the hip
`peg is locked in place. The optional features mentioned previously for slot 18 are also
`options for the slot in the hip pin. Also, optionally, the distance between tab 20 and the
`tab inside hole 32 is such that the hip peg and hip pin do not both lock at the same time,
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`but one of them locks first, as adapter 24 is screwed down, and then the other one locks as
`adapter 24 is screwed down further. Alternatively, if it is not important to allow the hip
`pin freedom to move a limited distance when it is locked, there is no tab inside hole 32,
`and the inside of hole 32 hits the side of the hip pin and locks it in place, or there is a tab
`or some other projection inside hole 32 which hits the side of the hip pin and locks it in
`place. In still another alternative, shown in Fig. 4, the hip pin and hip peg each has its
`own locking mechanism, and the hip pin and hip peg may each be locked or not,
`regardless of whether the other one is locked.
`In the embodiments of the invention shown in Figs. 1A through 4, locking
`10 mechanism 22 locks hip peg 10 while avoiding interfering with the hip pin, because hole
`32 in locking mechanism 22 allows locking mechanism 22 to go around the hip pin
`without touching it. Alternatively or additionally, as shown in Fig. SA, there is a hole 31
`in a hip pin 25, which allows hip pin 25 to go around locking mechanism 22 without
`interfering with locking mechanism 22. If it is desired for hip pin 25 to have a limited
`range of axial motion with respect to nail 12, rather than being rigidly held in place, then
`hole 31 is made wider than locking mechanism 22, by an amount equal to the desired
`range of motion. Optionally, hole 31 is elongated, so that hip pin 25 is movable over a
`range of axial positions. Alternatively or additionally, there are two or more holes 31 at
`different locations along hip pin 25, so that hip pin 25 can be locked at two or more
`discrete positions. Optionally, there are markings on the outside of hip pin 25 that also
`reach outside the bone, which show the surgeon how far to insert hip pin 25 into hole 14,
`and/or how far to tum it, so that hole 31, or one of several holes 31, is positioned and
`oriented in such a way that locking mechanism 22 goes through it. Alternatively, if hip pin
`25 does not need to be rotated, then hip pin 25, or at least the proximal end of hip pin 25,
`optionally has a non-circular cross-sectional shape, and hole 14 has the same non-circular
`shape, so that hip pin 25 can only be inserted into hole 14 with the correct orientation
`which allows locking mechanism 22 to go into hole 31. Even ifhip pin 25 does need to be
`rotated, a non-circular cross-sectional shape of hip pin 25 optionally shows the surgeon
`the orientation that hip pin 25 needs to have when it is finished rotating, in order to insert
`locking mechanism 22. If there is only one hole 31 in hip pin 25, the proximal end of hip
`pin 25 is optionally made wider than hole 14, or there is a protusion on the side of hip pin
`25, so that hip pin 25 can only be inserted far enough into hole 14 to align hole 31 with
`locking mechanism 22.
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`In still another alternative, shown in Fig. SB, there is a slit 33 in hip pin 2S instead
`of a hole, extending from the distal end of hip pin 25 up past the part of hip pin 2S that
`crosses the path of nail 12 when hip pin 2S is in place; Having such a slit instead of a hole
`in hip pin 2S facilitates the insertion of hip pin 25 into nail 12 after the end of locking
`S mechanism 22 is pushed past hole 14. Having a slit instead of a hole in hip pin 2S also
`means that hip pin 2S is adjustable to any desired axial position over a broad range, and
`that hip pin 2S need not be locked when hip peg 10 is locked by locking mechanism 22. It
`is still possible if desired to use locking mechanism 22 to lock hip pin 2S, for example by
`a tab attached to the side of locking mechanism 22 which fits into a slot, or one of a series
`of slots, to the side of slit 33 in hip pin 2S.
`In the examples ofFigs. SA and SB, hip pin 2S cannot be rotated if it is one solid
`piece (for example, to screw it down if it uses screw threads) once locking mechanism 22
`for hip peg 10 is pushed past hip pin 25. Alternatively, as shown in Fig. SC, there are two
`parallel hip pins 43, with a space 29 in between them, and locking mechanism 22 goes
`through space 29 between the two hip pins, not interfering with the hip pins. This allows
`each of the hip pins to rotate even after locking mechanism 22 is pushed past them.
`Alternatively, there is only one hip pin 2S, without a hole or a slit, and locking mechanism
`22 for hip peg 10 also does not have a hole, but one or both of locking mechanism 22 and
`hip pin 2S do not intersect the axis of nail 12, but pass to the side of the axis, so locking
`20 mechanism 22 and the hip pin 2S do not interfere with each other. Fig. 5C would illustrate
`such a configuration if one of the two hip pins 2S in Fig. SC, and the corresponding hole
`of the two holes 14, were removed from the drawing.
`It is possible, if desired, to use locking mechanism 22 to lock hip pin 25, even if
`there is a very elongated hole 31 in an embodiment similar to that shown in Fig. SA, so
`that the axial motion of hip pin 25 is not limited very much, and even in embodiments
`similar to those shown in Fig. SB and Fig. SC where the axial motion of hip pin 2S is not
`limited at all, or is limited only in one direction. Two exemplary ways to do this lrre
`shown in Figs. 5D and SE. Figs. SD and SE illustrate such mechanisms for the case of a
`hip pin with a slit 33 in it, as in Fig. 5B, but similar mechanisms could be used for the
`cases of a hip pin with an elongated hole 31 in it, as in Fig. SA, and for the case of two hip
`pins, as in Fig. 5C. In Fig. SD, locking mechanism 22 comprises an adapter 24, a coupling
`mechanism 36, and a stem 26, similar to the locking mechanism in Fig. 2. This allows
`adapter 24 to be threaded and to rotate, pushing stem 26 axially, without stem 26 rotating.
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`Stem 26 optionally has a tab 35 which fits into a slot 37 on the side of slit 33 in hip pin