Abstract
A graft ligament anchor includes a tubular body having a bore therethrough and proximal and distal ends. A flange is attached to the tubular body at the proximal end thereof and extends radially outwardly beyond the tubular body. A deformable wall is disposed in the tubular body bore and defines, at least in part, a chamber for retaining the graft ligament therein. An expansion device is configured for insertion into the tubular body axially of the tubular body, and for impinging upon the deformable wall to press the deformable wall, and hence the graft ligament received in the chamber, toward a wall of the bore, whereby to fix the graft ligament in the tubular body.
Claims
1. A graft ligament anchor comprising: an expandable ligament carrier for insertion into a bone tunnel, said ligament carrier comprising: a central channel extending lengthwise within the ligament carrier; four lengthwise-extending external grooves for receiving a graft ligament, wherein each of the four lengthwise-extending external grooves comprise widthwise-extending ridges for engaging a graft ligament disposed in the lengthwise-extending external groove; and an expansion screw for insertion into said central channel of said ligament carrier for expanding said ligament carrier outwardly toward an internal wall of the bone tunnel, whereby to fix a graft ligament disposed in a lengthwise-extending external groove against a side wall of the bone tunnel.
2. A graft ligament anchor according to claim 1 wherein said ligament carrier is provided with at least one detent extending outwardly from said ligament carrier and disposed proximate a proximal end of said ligament carrier.
3. A graft ligament anchor according to claim 1 wherein said ligament carrier is of a length exceeding a length of said expansion screw.
4. A graft ligament anchor according to claim 1 wherein the ligament carrier comprises a proximal end and a distal end, and further wherein the distal end comprises slits for permitting expansion of the ligament carrier.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered, together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:
(2) FIG. 1 is a diagrammatic illustration of a ligament anchoring application conducted in accordance with one aspect of the present invention;
(3) FIG. 2 is an exploded perspective view of one form of graft ligament anchor illustrative of an embodiment of the invention;
(4) FIG. 3 is an end view of the anchor tubular body portion of FIG. 2;
(5) FIG. 4 is an end view of an alternative embodiment of the anchor tubular body portion;
(6) FIG. 5 is a perspective view showing another alternative embodiment of the anchor tubular body portion;
(7) FIG. 6 is a side elevational view of the tubular body portion embodiment of FIG. 5;
(8) FIG. 7 is a perspective view of another alternative embodiment of the anchor tubular body portion;
(9) FIG. 8 is a side elevational view of the embodiment of FIG. 7, shown in place in a bone tunnel;
(10) FIG. 8A is a perspective view of another alternative embodiment of the anchor tubular body portion;
(11) FIG. 9 is an exploded perspective view of another alternative embodiment of graft ligament anchor;
(12) FIG. 10 is a sectional view taken along line 10-10 of FIG. 9;
(13) FIG. 11 is similar to FIG. 9, but showing still another alternative embodiment of ligament anchor;
(14) FIG. 12 is similar to FIG. 11, but showing still another alternative embodiment of ligament anchor; and
(15) FIG. 13 is a perspective view of an alternative embodiment of the anchor tubular body portion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(16) Referring first to FIG. 1, it will be seen that in one application of the graft ligament anchor, bone tunnels T.sub.F and T.sub.B are formed in a femur F and tibia B, respectively. A graft ligament L is anchored at one end (not shown) in the femur F by means well known in the art, and extends from femoral tunnel T.sub.F and into tibial tunnel T.sub.B and therethrough. The free end of graft ligament L extending from a tunnel opening P on a tibial surface S must be anchored to tibia B, so that graft ligament L is secured at both ends and essentially duplicates the function of the aforementioned ACL.
(17) Referring next to FIGS. 1-3, it will be seen that, in one illustrative embodiment, the inventive graft ligament anchor 10 includes a tubular body 12 having a bore 14 extending therethrough and having a proximal end 16 and a distal end 18. An annular flange 20 is fixed to tubular body 12 at proximal end 16 thereof, and extends radially outwardly beyond body 12. Flange 20 may be continuous; interrupted, or a partial flange, the former being shown in FIGS. 2-8 and the latter being shown in FIG. 9.
(18) One or more deformable walls 22 (four such walls 22 are shown in FIGS. 2 and 3) are formed in tubular body bore 14 and define, in conjunction with tubular interior body wall 21, elongated chambers 23 which extend lengthwise within tubular body 12. Elongated chambers 23 are each adapted to receive and retain a graft ligament L therein.
(19) An expansion device 24 (FIG. 2), such as a wedge, wedge-shaped screw or the like, is adapted for insertion into tubular body 12 axially of the tubular body, for impinging upon deformable walls 22 so as to press deformable walls 22, and hence the graft ligament L received in an elongated chamber 23, toward wall 21 of bore 14, whereby to fix graft ligament L against wall 21, and thereby to fix graft ligament L in tubular body 12.
(20) Tubular body 12 and annular flange 20 may be formed as a single integral unit, preferably of a substantially rigid plastic or metal material.
(21) Tubular body 12 may be provided with one or more openings 26 which may be in the form of elongated slots (FIGS. 2, 5, 6, 7 and 8) or orifices (FIG. 9). Openings 26 communicate with the interiors of chambers 23 and permit cells from the bone tunnel walls to migrate into tubular body 12 and chambers 23 during the healing process and further lock graft ligament anchor 10 and graft ligament L in place in tibial tunnel T.sub.B. Furthermore, the openings 26 also serve to receive outwardly-pressed portions of the graft ligament L, which helps to further secure the graft ligament L to tubular body 12.
(22) In FIG. 4, there is shown an alternative embodiment of graft ligament anchor 10 in which the deformable walls 22 comprise sleeves 22a defining elongated chambers 23 for receiving and retaining graft ligament L.
(23) Referring next to FIGS. 5 and 6, it will be seen that, in an alternative embodiment of graft ligament anchor 10, the axis x-x of tubular body 12 intersects a plane y-y of annular flange 20 at an acute angle z. The angle z permits flange 20 to lie flat against the tibial surface S, which surface S is typically not normal to the longitudinal axis of tunnel T.sub.B in ACL reconstructions. Tubular body 12 may be provided with the aforementioned openings or slots 26, as shown in FIGS. 5 and 6.
(24) Referring next to FIGS. 7 and 8, it will be seen that in another alternative embodiment of graft ligament anchor arms 28, 30 extend axially and proximally from tubular body proximal end 16. Annular flange 20 is mounted on the proximal ends of arms 28, 30. The arms 28, 30, being of relatively thin structure, provide a degree of flexibility, even if made in unitary fashion as extensions of tubular body 12, and permit annular flange 20 to assume a position essentially flat against tibial surface S, while tubular body 12 extends into bone tunnel T.sub.B at an acute angle to the plane of flange 20. Again, as seen in FIG. 8, tubular body 12 of this embodiment of graft ligament anchor 10 may be provided with openings 26 for migration of bone material therethrough.
(25) Referring next to FIG. 8A, it will be seen that in another alternative embodiment of graft ligament anchor 10, the annular flange 20 is pivotally connected to arms 28, 30 by means of a pair of pins 31. This construction permits arms 28, 30 to be formed relatively thick and rigid, yet permits annular flange 20 to assume a position essentially flat against tibial surface S while tubular body 12 extends into bone tunnel T.sub.B at an acute angle to the plane of flange 20.
(26) In essence, with the embodiment of FIGS. 7 and 8, deflection of arms 28,30 permits flange 20 to assume the desired position relative to tubular body 12, whereas with the embodiment of FIG. 8A, pivot pins 31 permit flange 20 to assume the desired position relative to tubular body 12.
(27) In operation, the graft ligament L is first anchored in the femur F in ways well known in the art, and extended out through tunnels T.sub.F and T.sub.B, and out the tunnel opening P. Then the graft ligament L is fed through one of the elongated chambers 23 of tubular body 12. Tubular body 12 is then inserted into tunnel T.sub.B by way of opening P, and advanced in tunnel T.sub.B until flange 20 engages bone surface S. The engagement of flange 20 with bone surface S will prevent tubular body 12 from advancing further into tibia B. The graft ligament L, which extends out of proximal end 16 of tubular body 12, is then pulled taut, and expansion device 24 is advanced into bore 14, engaging deformable walls 22 (or, alternatively, deformable walls 22a) and pressing the deformable walls, and hence the graft ligament L received within one of the elongated chambers 23, toward the interior wall of bore 14. Inasmuch as tubular body 12 is relatively rigid, deformable walls 22 compress against the bore wall and hold the graft ligament in that position.
(28) At this point, graft ligament L will be securely fastened to bone B, inasmuch as (1) expansion device 24 holds graft ligament L securely to tubular body 12, (2) annular flange 20 prevents tubular body 12 from being pulled further into tibia bone B, and (3) the graft ligament L prevents tubular body 12 from falling out of bone tunnel T.sub.B. In this respect it should be appreciated that, inasmuch as graft ligament L is typically slightly elastic in nature, and inasmuch as graft ligament L is pulled taut prior to fastening to tubular body 12, graft ligament L will tend to hold tubular body 12 in bone tunnel T.sub.B under tension.
(29) The free end of graft ligament L can then be trimmed off at tibial surface S.
(30) It should be appreciated that once expansion device 24 has been fully inserted into tubular body 12, and once the free end of graft ligament L has been trimmed off at tibial surface S, only annular flange 20 will protrude above tibial surface S. Since annular flange 20 is relatively thin, graft ligament anchor 10 has a low profile relative to tibial surface S. This can be important for patient comfort, particularly inasmuch as relatively little tissue overrides this portion of the patient's tibia.
(31) If the graft ligament anchor is provided with openings 26, cells from the bone tunnel wall can, during the healing process, migrate through openings 26 and into chambers 23 so as to further lock the tubular body and graft ligament in place.
(32) It should be appreciated that the deformable walls 22 (or, alternatively, the deformable walls 22a) of chambers 23 serve to protect the graft ligament L from cutting or other damage by expansion device 24, spread the pressure from expansion device 24 substantially evenly on the graft ligament L, and provide improved friction against the graft ligament.
(33) It should also be appreciated that, inasmuch as expansion device 24 fastens graft ligament L to tubular body 12, and inasmuch as the structural integrity of tubular body 12 can be carefully controlled during the manufacturing process, graft ligament anchor 10 will form a secure attachment even when tibia B has relatively poor bone quality.
(34) It should also be appreciated that, inasmuch as a plurality of elongated chambers 23 are provided in tubular body 12, graft ligament anchor 10 can be used to simultaneously fasten a plurality of graft ligament free ends to tibia B.
(35) In FIG. 9, there is shown an alternative embodiment of graft ligament anchor in which flange 20 is a partial flange, deformable walls 22 are omitted from the interior of tubular body 12, and openings 26 in tubular body 12 are in the form of a multitude of orifices. This embodiment includes a ligament carrier 32 having lengthwise-extending grooves 34 formed therein for receiving the graft ligament L which is to be anchored. The grooves 34 each may be provided with widthwise-extending ridges 35 which assist in holding the graft ligament L in a groove 34. Expansion device 24, in this embodiment, is preferably a screw which is driven into a central channel 36 (FIGS. 9 and 10) of ligament carrier 32. The distal end 38 of ligament carrier 32 is provided with slits 40 which permit expansion of ligament carrier 32. Furthermore, as shown in FIG. 10, central channel 36 and outer grooves 34 define thin walls 42 which can expand against a graft ligament L received in an outer groove 34, thereby pressing the graft ligament against the interior wall of tubular body bore 14.
(36) If desired, the tubular bodies 12 may also be provided with interior ridges, such as the interior ridges 39 shown in FIG. 5 or corresponding ridges (not shown) for the embodiment of FIG. 9, disposed on the interior wall of tubular body bore 13, for enhanced engagement with the graft ligament L pressed thereagainst.
(37) Preferably, ligament carrier 32 is provided with a detent 48 extending outwardly from the ligament carrier and disposed near a proximal end 50 of the ligament carrier. Where tubular body 12 is to be used in conjunction with the ligament carrier 32, tubular body 12, at its proximal end 16, is provided with a recess 52 which is complementary to detent 48 and adapted to receive the detent, so as to limit advancement of ligament carrier 32 into tubular body 12.
(38) Preferably, but not necessarily, the length of ligament carrier 32 exceeds the length of tubular body 12, such that when ligament carrier 32 is fully engaged with tubular body 12, a distal portion of ligament carrier 32 extends beyond the distal end of tubular body 12.
(39) In operation, graft ligament L is first anchored in femur F and extended out through tunnels T.sub.F and T.sub.B and out tunnel opening P. Then graft ligament L is fed through tubular body 12. Next, tubular body 12 is inserted into tunnel T.sub.B until flange 20 engages bone surface S (FIG. 9). Then graft ligament L is positioned in one of the outer grooves of ligament carrier 32. Ligament carrier 32 is then inserted into bore 14 of tubular body 12 until the distal end portion of ligament carrier 32 protrudes distally from the distal end of tubular body 12 and carrier detent 48 engages tubular member recess 52, which prevents further advancement of ligament carrier 32 into tubular body 12. Graft ligament L, which extends out of ligament carrier 32 and tubular body 12, is then pulled taut, and expansion device 24 is advanced into the ligament carrier's channel 36, engaging deformable walls 42 and pressing the walls 42, and hence the graft ligament L received in one of the ligament carrier's outer grooves 34, toward the interior wall of bore 14. Inasmuch as tubular body 12 is relatively rigid, deformable walls 42 compress against the interior bore wall of tubular body 12 and hold the graft ligament in that position. At the same time, flange 20 prevents tubular body 12 from being pulled further into tibia B, and the graft ligament prevents tubular body 12 from falling out of bone tunnel T.sub.B. In this respect it should be appreciated that, inasmuch as graft ligament L is slightly elastic in nature, and inasmuch as graft ligament L is pulled taut prior to fastening to tubular body 12, graft ligament L will tend to hold tubular body 12 in bone tunnel is under tension.
(40) The free end of graft ligament L can then be trimmed off at tibial surface S.
(41) It should be appreciate that, with the foregoing construction, distally of the distal end of tubular body 12, ligament carrier 32 presses the graft ligament directly against interior walls of tibial tunnel T.sub.B. Thus, graft ligament L is effectively locked to tubular body 12 and is also pressed directly against the walls of tibial tunnel distal to tubular body 12. This arrangement provides a stress transition for graft ligament L inasmuch as the graft ligament is held in tubular body 12 under relatively high stress, is held under less stress by ligament carrier 32 in tibial tunnel T.sub.B immediately distally of tubular body 12 and, distally of ligament carrier 32, is not pressed against tibial tunnel T.sub.B. This transitional arrangement provides improved graft stabilization and immobilisation, and helps minimize abrasive movement of the graft ligament against bone surfaces during knee flexure. Furthermore, by providing an enhanced region of direct contact between graft ligament L and the walls of the bone tunnel, biological fixation of the graft ligament to the bone will be enhanced.
(42) It should also be appreciated that once expansion device 24 has been fully inserted into ligament carrier 32, and once the free end of graft ligament L has been trimmed off at tibial surface S, only annular flange 20 will protrude above tibial surface S. Again, since annular flange 20 is relatively thin, graft ligament anchor 10 has a low profile relative to tibial surface S. This can be important for patient comfort, particularly inasmuch as relatively little tissue overrides this portion of the patient's tibia.
(43) It should also be appreciated that, inasmuch as expansion device 24 fastens graft ligament L to tubular body 12, and inasmuch as the structural integrity of tubular body 12 can be carefully controlled during the manufacturing process, the graft ligament anchor shown in FIGS. 9 and 10 will form a secure attachment even when tibia B has relatively poor bone quality.
(44) It should also be appreciated that, inasmuch as a plurality of lengthwise-extending grooves 34 are provided in ligament carrier 32, the graft ligament anchor can be used to simultaneously fasten a plurality of graft ligament free ends to tibia B.
(45) Cells from the bone tunnel wall, in due course, can thereafter migrate through openings 26, and around the graft ligament, so as to further lock tubular body 12 and graft ligament L in place.
(46) In FIG. 11, there is shown another alternative embodiment of graft ligament anchor, generally similar to the embodiment shown in FIG. 9, but having tubular body portion 12 provided with external screw threads 44 rather than flange 20. The embodiment of FIG. 11 is used in much the same manner as the embodiment of FIG. 9, except that before graft ligament L is anchored in femur F, tubular body 12 is screwed into bone tunnel T.sub.B. To facilitate the screwing rotation, tubular body 12 may be provided with slots 46 for receiving a screw driver (not shown). Ligament carrier 32 is provided with one or more detents 48 which is/are complementary to slots 46, and received by slots 46, so as to limit advancement of ligament carrier 32 into tubular body 12. The tubular body 12 may be provided with interior ridges, of the type illustrated in FIG. 5, to assist in the fixation of the graft ligament L to tubular body 12. And tubular body 12 may be provided with openings 28 to permit cells from the bone tunnel walls to migrate into tubular body 12 and to receive outwardly-pressed portions of the graft ligament L, in the manner previously discussed.
(47) In operation, the tubular body 12 is screwed into bone tunnel T.sub.B until proximal end 16 is inboard of bone surface S. Inasmuch as the position of threaded tubular body 12 is easily controlled and unlikely to migrate in the bone tunnel, there is no need for a flange, such as flange 20. Once tubular body 12 is in place, the graft ligament is anchored in the femoral tunnel T.sub.F and the remainder of the operation proceeds substantially as set forth above relative to the embodiment of FIG. 9.
(48) In FIG. 12, there is shown still another alternative embodiment of graft ligament anchor, similar to the embodiments of FIGS. 9 and 11, but wherein the expansion device 24 comprises a mandrel 56, rather than a screw device. The mandrel 56 may be deployed by a gun (not shown) into the carrier 32 and may be provided with ridges 58 for engaging the walls of channel 36 of carrier 32, which walls may include opposing ridges to prevent withdrawal of mandrel 56 from channel 36. Otherwise, the assembly of FIG. 12 is used in much the same manner as the assemblies of FIGS. 9 and 11.
(49) With the embodiments in FIGS. 11 and 12, external screw threads 44 prevent tubular body 12 from being pulled further into bone tunnel T.sub.B under the tension of graft ligament L. To that extent, external screw threads 44 serve the same purpose that external flange 20 serves with the embodiments of FIGS. 1-8, 8A and 9. In this respect it will be appreciated that with the embodiments of FIGS. 11 and 12, once expansion device 24 has been fully inserted into ligament carrier 32, and once the free end of graft ligament L has been trimmed off at tibial surface S, substantially none of the graft ligament anchor will protrude above tibial surface S. This can be important for patient comfort, inasmuch as relatively little tissue overrides this portion of the patient's tibia.
(50) The tubular body 12 shown in FIGS. 2-9 may be substantially rigid or may be slightly expandable to enable the tubular body to more snugly engage the bone when expansion device 24 is set within the tubular body. In the latter case, the expansion capability may be provided for by having the tubular body 12 formed out of a plastic material, or by providing, in an otherwise substantially rigid body, a mechanical means for permitting expansion. In this latter regard, there is shown in FIG. 13 a tubular body 12 having opposed lengthwise free edges 60, 62 having tongues 64 and grooves 66 formed thereon, respectively. Limited expansion of the tubular body 12 is permitted within the confines of the tongue-and-groove arrangement.
(51) It should be appreciate that, by providing (1) tubular body 12, and (2) an external flange 20 or external screw threads 44 for stabilizing tubular body 12 relative to the adjacent bone, and (3) deformable walls 22, 22a, or ligament carrier 32, and expansion device 24 for making the graft ligament fast to tubular body 12, the graft ligament L can be securely attached to a host bone. This is true regardless of whether such attachment is to relatively hard outer cortical bone, or to relatively soft inner cancellous bone, or even where the host bone has relatively poor bone quality.
(52) It should also be appreciated that, while in the foregoing description the graft ligament anchor of the present invention has been discussed in the context of attaching one end of a graft ACL to the tibia, the graft ligament anchor could also be used to attach one end of the graft ACL to the femur, or to attach a graft ligament to another bone in the body.
(53) It should also be appreciated that, with respect to the graft ligament anchor shown in FIGS. 9-12, ligament carrier 32 might be omitted altogether, and expansion device 24 might be used to attach the graft ligament L directly to the side wall of tubular body 12. Of course, in such a situation, since expansion device 24 will be directly engaging graft ligament L, it is important that expansion device 24 be constructed so that it will not cut or otherwise damage graft ligament L. In such a situation, expansion device 24 might comprise a so-called non-cutting interference screw of sort manufactured by Arthrex.
(54) Furthermore, it should also be appreciated that, with respect to the graft ligament anchor embodiments shown in FIGS. 9-12, tubular body 12 might be omitted altogether, and ligament carrier 32 might be used to attach the graft ligament L directly to the side wall of the bone tunnel. Of course, in such a situation, the attachment of the graft ligament L to the host bone might be somewhat less secure than where tubular body 12 is used, particularly where the host bone is relatively soft cancellous bone or where the host bone is of relatively poor bone quality. Furthermore, in such a situation, it might fee desirable to increase the size of the ligament, carrier's detents 48 so that they can act as stops to prevent the ligament carrier from being drawn into the bone tunnel due to ligament tension.
(55) Thus there is provided an improved graft ligament anchor which is simple in construction, inexpensive to manufacture, easy to handle and install, and reliable and safe in operation.
(56) In addition, the graft ligament anchor can easily and reliably anchor a graft ligament in a bone of relatively poor quality.
(57) There is further provided an improved method for attaching a graft ligament to a bone.
(58) It is to be understood that the present invention is by no means limited to the particular constructions and methods herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims, for example, in illustrative embodiments described hereinabove, ligament carrier 32 is illustrated with external ridges 35 (FIG. 9), tubular body 12 is illustrated with interior ridges 33 (FIG. 5), an expansion device 24 is provided with ridges 58 (FIG. 12). It will be apparent to those skilled in the art that such ridges effect a gripping facility by virtue of providing a textured surface. Appropriate and useful surfaces may be rendered textured by means other than, or in addition to, ridges, such as by lands, grooves, steps, teeth, apertures, roughened portions, and the like. Among other things, it has been found that graft ligament fixation can be improved where such textured surfaces cause the graft ligament to assume a somewhat convoluted or tortuous path on a localised basis, e.g., as the graft ligament extends over a series of adjacent ridges.
