Title: Securing Means for Surgical Use
The present invention relates to a securing means for surgical use, for securing soft tissues or sutures or other components to bone.
At present, components which need to be anchored to bone usually are anchored by drilling a hole through the bone, drawing either the component or a suture secured to the component through the hole, and tying off the component/suture to a securing button which rests over the top of the hole. This method works reasonably well, but is fiddly to use, and the components being secured are not always drawn tightly into the hole, and the tension on the components/suture cannot be adjusted.
It is therefore an object of the present invention to provide a securing means which is both more secure and easier to use than the equipment currently available.
The present invention provides a securing means for surgical use which includes an elongated tie having an engagement means at at least one end; and a locking device adapted to engage the tie to secure the tie and the locking device in a predetermined position.
A preferred embodiment provides a securing means for surgical use which includes: an elongated tie having an engagement means at at least one end; a locking device which provides an engagement surface for engaging the surface of a bone and a body secured to the engagement surface, the body being apertured to permit the tie to pass therethrough; and locking means provided on one or both of the elongated tie and the locking device, such that the locking device can engage the tie to secure the tie and the locking device in a predetermined position.
The locking means and locking device may include any of a wide range of designs adapted to inter-engage, for example:-
1. At least a portion of the tie may be formed with locking means in the form of ratchet teeth, and the locking device may provide internal protrusions or walls adapted to engage with the ratchet teeth. 2. At least a portion of the tie may be formed with locking means in the form of a buttress thread and the locking device may provide internal protrusions adapted to engage with the thread. 3. At least a portion of the tie may be formed with locking means in the form of a deformable surface and the locking device may provide internal teeth that bite into, and lock against, the deformable surface. 4. At least a portion of the tie may be formed with a locking means in the form of a screw thread, and the locking device may provide a complimentary internal screw thread.
The engagement means may be one or more holes (eyes) or an enlarged portion, e.g. frustro-conical.
Preferably, an engagement means in the form of an eye suitable for receiving a suture is formed at the leading end of the tie. The trailing end preferably has a frustro-conical end with an eye through which soft tissue can be looped.
Preferably, the eye at the trailing end of the tie is designed to seal in the lower end of the hole through the bone to prevent pressure erosion of the hole. Pressure erosion tends to occur in any areas of pressure differential, and can cause serious erosion of the bone.
Most preferably, the hole through the bone is sealed at both top and bottom:- at the top by means of engagement between the locking device and the top of the hole, and at the bottom by the tie, either by direct engagement between the tie eye and the bone or a washer, and/or by engagement between the bone/washer and soft tissue, (e.g. a tendon graft) secured to the tie eye.
By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawings in which:- Fig. 1 is a diagrammatic longitudinal section showing the tie of the present invention in use in an aperture through a bone;
Fig. 2 is a plan view of a locking device for use with the tie of the present invention; Fig. 3 is a section on Line A - A of Fig. 2; Fig. 4 is a side view of one embodiment of a tie of the present invention;
Fig. 5 is a view of the tie of Fig. 4 rotated through 90° about its longitudinal axis;
Fig. 6 is a diagrammatic cross-section showing a second type of locking device;
Fig. 7 is a cross-section through the locking device shown in Fig. 6; Fig. 8 is a diagrammatic longitudinal section through another design for one end of a tie;
Fig. 9 is a side view of a further embodiment of a tie;
Fig. 9a is a view of the tie of Fig. 9 rotated through 90° about its longitudinal axis;
Fig. 10 is a section through a locking device for use on a sloping surface;
Fig. 11 is a side view of a tie with a buttress thread; Fig. 12 is a side view of a tie with a screw thread;
Fig. 13 is a diagrammatic longitudinal section showing the locking washer of the present invention used to secure tissue against bone; and
Fig. 14 is a longitudinal section through a two-piece locking device.
Referring to Fig.s 1-5, a tie 2 in accordance with a first embodiment of the invention consists of a strip of suitably strong, tough, medically acceptable, nonelastic material, formed with engagement means in the form of an enlarged frustro-conical portion 3 at one end and a pointed tip 4 at the other end. The enlarged frustro-conical portion 3 and the tip 4 both are apertured, with apertures 5 and 6 respectively. Only one aperture 5,6 is shown, but multiple apertures may be provided if necessary.
A portion 7 of the tie 2 is formed with a series of pairs of ratchet teeth 8, all pointing in the same direction. The portion 7 is depicted with one set of opposed pairs of ratchet teeth, but the tie may be formed with two or more sets if required. As shown in Fig. 9/9a, the opposed rows of ratchet teeth 18 may be offset, to give a wider range of adjustment relative to the locking device. Further, the tie 2 is depicted with all or most of the length of the tie formed with ratchet teeth, but only a portion of the tie may be formed with teeth (see Fig. 6).
Referring in particular to Fig.s 2-3, a locking device 10 consists of an engagement surface in the form of a disk 11 with a central aperture 12 and an apertured frustro-conical body 13, one edge of which is formed integrally with the disk 11 ; the other edge of the body 13 is formed with an inturned hook 14. Referring to Fig. 1 , in use the tie 2 is used to secure soft tissue such as a tendon graft (not shown) to bone 15 as follows:- a hole 16 of a slightly larger diameter than the outer diameter of the toothed portion 7 of the tie 2 is drilled through the bone 15. The upper end 16a and the lower end 16b of the hole 16 both are tapered to a frustro-conical shape which matches the taper of the body 13 and enlarged frustro-conical portion 3 respectively. The tendon graft is threaded through the aperture 5 in the enlarged diameter end 3. The pointed tip 4 of the tie 2 is then pulled with a lead suture through the hole 16 in the direction of Arrow T, and the locking device 10 is dropped over the pointed tip 4 of the tie 2 until the underside 11 a of the disk 11 rests flat on the surface of the bone 15b surrounding the end 16a of the hole 16 remote from the tendon graft, and the body 13 engages the tapered end 16a of the hole, to seal that end of the hole.
The locking device 10 will slide over the ratchet teeth 8 in the direction of Arrow S, but cannot move in the reverse direction because of the engagement between the tips of the ratchet teeth 8 and the inturned hooks 14. Thus, the tie 2 can be tightened towards the bone 15 simply by pulling the tip 4 of the tie in the direction of Arrow T, and the locking device 10 will secure the tie against the bone 15 in the required position. The tie 2 may be tightened manually (e.g. by using a handle passed through the aperture 6) or may be tightened using a calibrated tensioning device which indicates the tension being applied to the tie. It is envisaged that a removable sleeve may be used during tightening to engage the surface of the locking device 10 and hold it in position against the surface 15 b of the bone.
The locking device 10 not only locks the tie in position, but also spread the load on the bone 15 over a larger area; the size of the disk 11 may be increased as necessary if the load is greater or if the bone is soft or damaged. If the locking device 10 needs to sit evenly on a sloping bone surface, the disk 11 may be wedge-shaped in side view to compensate for the slope of the bone, as shown in Fig. 10.
When the tie 2 is locked in the above described position, the walls of the frustro-conical portion 3 at the end of the tie engage with, and seal against, the tapered lower end 16b of the hole 16; this seals the lower end of the hole. The frustro-conical portion 3 and the end 16b of the hole may be made in other shapes, but preferably are tapered. Preferably, both the upper and lower ends of the hole 16 are sealed as described above, since this is the best way to ensure that there is no pressure erosion of the bone due to pressure differentials. However, if it is not feasible to seal the upper end 16a of the hole, then the lower end 16b only may be sealed.
If it is not feasible to form a tapered hole at the lower end 16b of the hole 16, a grip washer 20 (shown in broken lines in Fig. 1) may be used. The grip washer 20 provides teeth 20a on the surface of the washer adjacent to the bone surface 15a, so that the washer digs into the bone and engages it firmly. The grip washer 20a is formed with a frustro-conical aperture 20b on its lower surface, such that when the tie 2 is fully tightened, the frustro-conical portion 3 on the tie is in sealing engagement with the frustro- conical surface 20b; this provides an effective seal for the lower end of the hole 16.
However, in cases where soft tissues (such as a tendon graft) are engaged with the aperture(s) 5 of the frustro-conical portion 3, the soft tissues themselves form, or help to form, the seal between the portion 3 and the end 16b of the hole or the aperture 20b of the washer 20.
If a grip washer 20 is used, an alternative technique may be used to secure tissues against the surface of the bone:- as shown in Fig. 13, the washer 20 is engaged with the enlarged frustro-conical portion 3 of the tie 2, and the tie is tightened and secured by a locking device 10 as described with reference to Fig. 1. However, instead of the soft tissue being secured to the aperture 5 of the portion 3, the soft tissue 40 is drawn between the surface 15a of the bone and the toothed surface of the washer 20, so that the teeth 2OA of the washer 20 pass through the soft tissue 40, and the pressure exerted by the tensioned tie holds the washer 20 tightly against the bone surface 15a; securing the soft tissue 40 in place.
Fig. 6 shows another design of locking device, which is suitable for use if it is necessary to countersink most of the locking device into the hole formed through the bone. The locking device 22 of Fig. 8 consists of a hollow cylindrical portion 23 having an enlarged head portion 24 which in use rests on the surface 15 b of the bone 15. As shown in Fig. 7, the locking device 22 is formed with a central aperture 25 which is sized to accommodate the tie 2 as a sliding fit therethrough, and a series of opposed pairs of locking surfaces 26 spaced along the length of the locking device 22, which project out into the central aperture 25, so as to engage the ratchet teeth 8 of the tie when the tie is pulled up through the locking device.
The locking device 22 is used in the same general manner as the locking device 10 i.e., it is slid over the tie from the pointed tip 4 and allows the tie to pass through in the direction of Arrow T, but engagement between the ratchet teeth 8 and the locking surfaces 26 prevents movement of the tie in the direction of Arrow S. It will be appreciated that the locking device 22 engages the tie over a greater area and therefore provides even greater security than the locking device 10. Locking surfaces 26 may be provided in a variety of different configurations, depending upon the configurations of the ratchet teeth with which they are to be used.
A locking device of the type shown in Fig.s 6 and 7 may also be used in combination with a tie formed with an engagement means in the form of a buttress thread, as shown in Fig. 11. In use, the locking surfaces 26 may be pushed over the buttress thread to form a locking engagement, but if it is necessary to remove the locking device 22 at some later stage, it can be unscrewed from the thread.
Another possibility is to modify the locking device of the type shown in Fig.s 6 and 7 by forming the locking surfaces 26 of a substantially harder material than the material of the tie 2, so that the locking surfaces can bite into the surface of the tie 2 to form a positive engagement with it. Alternatively, the locking surfaces 26 could be provided on the tie, and the locking device made of a softer material, so that the surfaces 26 bite into the locking device to secure the tie and locking device together.
A further variant is to form a locking device of the type shown in Fig.s 1 - 3 or Fig.s 6 and 7 with an internal screw thread, and form a complimentary screw thread on the corresponding section of the tie 2, as shown in Fig. 12.
Yet another variant is a two-piece locking device as shown in Fig. 14. In this design, a two-piece locking device 50 comprises an outer sleeve 51 and an inner sleeve 52. The outer sleeve 51 has a frustro-conical outer surface dimensioned and shaped to match the taper of the upper end 16a of the hole 16 in the bone 15. this outer surface may be formed with teeth 53 to help to retain the outer sleeve in the hole 16.
The wider end of the sleeve 51 is formed with a circumferential lip 54 which is designed to rest on the bone surface 15b and spread the load on that surface.
The inner surface of the sleeve 51 is formed with a plurality of spaced ratchet teeth 55, which are arranged to engage corresponding ratchet teeth 56 formed in the outer surface of the inner sleeve 52. The engagement between the teeth 55,56 permits the inner sleeve 52 to move in the direction of Arrow S, but to resist movement in the direction of Arrow T. The inner sleeve 52 provides a frustro-conical outer surface 57, with an angle of taper matching that of the outer sleeve 51 , and a circular cross-section central aperture 58, which has a uniform cross-section and is dimensioned to allow a tie 2 to be a sliding fit therethrough. The inner surface 58 of the sleeve 52 and the outer surface of the tie 2 are formed with ratchet teeth 59,60, respectively, to allow the tie to move easily in the direction of Arrow T, but to resist movement in the direction of Arrow S.
The use of a two-part locking device allows for a very fine adjustment of the tension applied by the tie 2;- the inner sleeve 52 can be adjusted in position relative to the outer sleeve 51 , as well as adjusting the position of the tie relative to the inner sleeve 52.
The ratchet teeth 55/56 and 59/60 may of course be replaced by buttress-thread or screw- threaded engagement.
The cylindrical locking device illustrated in Fig. 6 also may be made as a two-piece device, as described with reference to Fig. 14.
Fig. 8 shows another possible design for the end 3 of the tie shown in Fig.s 1 , 4, and 5. In this design, the end 3 is formed as a frustro-conical portion 30, formed integrally with the remainder of the tie 2. This is used in combination with an expanding toothed collar 31. The collar 31 may be made of a resilient material, so that the sides spring out into contact with the tapered lower end 16b of the hole 16, or the collar 31 may be formed such that the internal diameter of the collar is greater than the external diameter 'x' of the top of the frustro-conical portion 30, but less than the external diameter 'y' of the base of the portion 30.
In use, the collar 31 initially rests over the frustro-conical portion 30. As the tie 2 is tightened, the portion 30 and the collar 31 are pulled up into the tapered lower end 16b of the hole 16 through the bone 15. The collar 31 is slotted to allow its sides to expand. Further tightening of the tie forces the frustro-conical portion 30 up into the collar 31 , expanding the collar 31 and pushing the teeth 32 on the collar into engagement with the sides of the hole 16b, thus securing the end of the tie firmly in place. The outer surface of the frustro-conical portion 30 and/or the inner surface of the collar 31 may be formed with ratchet teeth 33,34, respectively, to lock the frustro-conical portion and collar together.
Any of the locking devices 10,24,50 may be formed with an integral insertion tube 70 as shown in broken lines in Fig. 1 ,6 and 14. In the case of the two-part locking device 50, the tube 70 is formed on the outer sleeve 51. The insertion tube 70 facilitates the handling and placement of the locking device and projects from the bone through surrounding soft tissues, protecting the soft tissues from damage during drilling and tensioning operations.
Depending upon the position of the locking device, the tube 70 can remain permanently attached to the locking device, or can be broken off when the operation is completed. The tube 70 may be formed with weakened zones to aid breaking the tube.
Any of the above-described locking devices may be provided with teeth on their outer surface, to give a stronger engagement between the device and the sides of the hole in the bone.