Abstract
A method and suture anchor for treatment of spinal stenosis. The method includes the steps of cutting off a muscle origin or insertion from a spinous process, cutting off the spinous process at the transition to the lamina arcus vertebrae, at least partial resection of the lamina arcus vertebrae and thereby decompression of the spinal cord within the foramen vertebral, performing osteosynthesis of the spinous process, and placing a suture anchor within the spinous process and reattaching the muscle origin or insertion to the spinous process. Further methods for spine stabilization are provided wherein suture anchors are used to implement a tension band wiring. Further methods for reduction of unwanted effects after spinal treatment are provided.
Claims
1. A method for the treatment of spinal stenosis comprising the following steps: cuttting off a muscle origin or insertion from a spinous process cutting off the spinous process at the transition to the lamina arcus vertebrae resecting at least a part of the lamina arcus vertebrae and thereby decompression of the spinal cord within the foramen vertebral performing osteosynthesis of the spinous process and placing a suture anchor within the spinous process and reattaching the muscle origin or insertion to the spinous process.
2. The method according to claim 1, wherein muscle origins or insertion are cut off only on the left side or on the right side but not on both sides of the spinous process.
3. The method according to claim 1, wherein the suture anchor comprises a material having thermoplastic properties and is anchored in the bone opening with the aid of vibratory energy used for in situ liquefaction of the material having thermoplastic properties.
4. The method according to claim 1, wherein the osteosynthesis of the spinous process is done using at least two anchors comprising a material having thermoplastic properties and are anchored in the bone opening with the aid of vibratory energy used for in situ liquefaction of the material having thermoplastic properties.
5. The method according to claim 1, wherein the osteosynthesis of the spinous process is done using a plate fully made of a bio-degradable material.
6. The method according to claim 1, wherein the spinal stenosis is a cervical spinal canal stenosis, thoracic spinal canal stenosis, lumbar spinal canal stenosis or wide spinal canal stenosis.
7. The method according to claim 1, wherein the origin or insertion of all muscles originating or inserting on one side of the spinous process are cut off.
8. The method according to claim 1, wherein the origin or insertion of at least one muscle selected from the group consisting of multifidi and rotatores, splenius capitis, splenius cervicis, semispinalis cervicis, semispinalis thoracis, and spinal erectors is cut off.
9. The method according to claim 1, wherein the suture anchor and the anchor used during osteosynthesis are implanted unicortical.
10. A method for spine stabilization comprising the following steps: positioning of one suture anchor per lamina arcus vertebrae or per pedicle of at least two adjacent vertebrae and knotting together suture ends of two anchors located in different vertebras at corresponding locations within the lamina arcus vertebrae or the pedicle.
11. The method according to claim 10, wherein the suture anchors comprise a material having thermoplastic properties and is anchored in the bone opening with the aid of vibratory energy used for in situ liquefaction of the material having thermoplastic properties.
12. The method according to claim 10, wherein the suture anchors are implanted only unicortical.
13. The method according to claim 10, wherein the lower of the adjacent vertebrae is joined to the vertebrae further down by spinal fusion.
14. The method according to claim 13, wherein the fusion is supplemented with hardware.
15. The method according to claim 10, wherein the knotted sutures are augmented using an artificial ligament.
16. A suture anchor for locking a suture relative to a hard tissue, wherein the suture anchor is designed to be fixed within an opening in the hard tissue and comprises: a material having thermoplastic properties; for holding the suture, a suture conduit at a distal end of the anchor; and an element for protecting the suture from contact with a section of the hard tissue.
17. The suture anchor according to claim 16, wherein the suture anchor is equipped for fixing the suture in a knot-less manner.
18. The suture anchor according to claim 17, wherein the suture anchor is equipped for fixing the suture in a knot-less manner using the material having thermoplastic properties.
19. The suture anchor according to claim 18, wherein the suture anchor comprises a collapsible suture guiding conduit or other structure of the thermoplastic material.
20. The suture anchor according to claim 16, wherein the suture anchor has a suture anchor body that has the conduit, and wherein the element for protecting the suture from contact with section of the tissue is equipped for protecting the suture from contact with a rim of an opening in the hard tissue and comprises a sleeve shaped to traverse a rim of the opening within the hard tissue and comprising a channel for the suture and being designed to fit to a proximal end of the suture anchor body.
21. The suture anchor according to claim 20, wherein the sleeve is rotatable relative to the anchor body.
22. The suture anchor according to claim 20, wherein the channel comprises a through opening extending through a portion of the sleeve.
23. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with wherein the suture anchor has a suture anchor body that has the conduit, and wherein the element for protecting the suture from contact with section of the tissue is equipped for protecting the suture from contact with a rim of an opening in the hard tissue and comprises a plate or disc shaped to be arranged proximally of the rim of the opening in the hard tissue and comprising a channel for the suture, the plate or disc being designed to fit to a proximal end of the suture anchor body.
24. The suture anchor according to claim 23, wherein the disc or plate is rotatable in respect to the anchor body.
25. The suture anchor according to claim 23, wherein the plate or disc has at least one channel for the suture
26. The suture anchor according to claim 25, wherein the channel has a through opening and/or notch in the disc or plate.
27. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with the tissue comprises a proximal lateral projection of the suture anchor, the projection comprising a channel for the suture, the projection shaped to shield the suture from a rim of the opening in the bone tissue.
28. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with the tissue has an extension causing a minimal distance between the suture and the hard tissue and a rim of the opening in the tissue of 2 mm.
29. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with the hard tissue is of a flexible foil material.
30. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with the hard tissue is of a thermoplastic foil material.
31. The suture anchor according to claim 16, wherein for the element for protecting the suture from contact with the hard tissue at least one of the following conditions holds: the element has a thickness of at most 1<mm and a Young's modulus of at most 0.5 GPa; the element has a thickness of at most 0.5 mm.
32. The suture anchor according to claim 16, wherein the element for protecting the suture from contact with the hard tissue with the exception of the at least one channel is rotationally symmetrical around a suture anchor axis.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0084] FIG. 1 shows a schematic overview of the method according to aspect 2 according to the present invention.
[0085] FIG. 2 shows a schematic overview of the method according to aspect 1 of the present invention.
[0086] FIG. 3 shows a schematic view of a thoracic vertebrae having openings with and without suture anchors for the method according to aspect 2 of the present invention.
[0087] FIG. 4 shows a schematic view of an anchor according to the invention. The anchor has at least one element to protect the suture from contact with the rim of the bone opening.
[0088] FIG. 5 shows a schematic view of the anchor according to FIG. 4 after anchoring in a bone opening.
[0089] FIG. 6 shows a schematic view of another anchor according to the invention. FIG. 6a shows the anchor prior to anchoring, FIG. 6b after anchoring in a bone opening. The anchor includes a sleeve as element to protect the suture from contact with the rim of the bone opening.
[0090] FIG. 7 shows a schematic view of a suture anchor according to the invention. The anchor has at least one element to protect the suture from contact with the rim of the bone opening.
[0091] FIG. 8 shows a schematic top view of the suture anchor according to FIG. 7.
[0092] FIG. 9 shows a schematic view of three suture anchors introduced into three adjacent vertebrae before the suture is adjusted or strained.
[0093] FIG. 10 shows a schematic top view of an anchor having at least one element to protect the suture from contact with the rim of the bone opening;
[0094] FIG. 11 shows a schematic side view and a top view of an anchor with a plate rotatable with respect to an anchor body that has the pin portion;
[0095] FIG. 12 shows a schematic cross section of an implanted anchor with a disc or plate rotatable with respect to the anchor body.
DETAILED DESCRIPTION OF THE INVENTION
[0096] The following more detailed description of the embodiments of the method is a representative of exemplary embodiments of the technology, wherein similar parts are designated by same numerals throughout. Standard medical planes of reference and descriptive terminology are employed in this specification. A sagittal plane divides a body into right and left portions. A transverse plane divides a body into superior and inferior portions. Anterior means toward the front of the body. Posterior means toward the back of the body. Superior means toward the head. Inferior means toward the feet. Medial means toward the midline of the body. Lateral means away from the midline of the body. Axial means toward a central axis of the body. Proximal means toward the trunk, or, in the case of an inanimate object, toward a user. Distal means away from the trunk, or, in the case of an inanimate object, away from a user. Dorsal means toward the top of the foot. Plantar means toward the sole of the foot. Ipsilateral means on the same side of the body. Contralateral means on the opposite side of the body.
[0097] FIGS. 1 illustrates the method according to aspect 2 of the present invention. Exemplarily, the method is shown at the cervical spine. The figure shows a fusion of the first thoracic vertebra 5 with vertebra prominens 3, the seventh cervical vertebra, which are shown with the spinal cord 1 and the articular capsule 4. Therefore, pedicle screws 9 together with a fusion rod 8 are used. The articulation between the seventh cervical vertebra 3 and the sixth cervical vertebra 2 is stabilized by a tension band wiring according to the second aspect of the invention. In a first step two bone openings 6 are made in each lamina arcus vertebrae of each vertebrae, therefore in total eight bone openings 6 are introduced. These openings do not have to be through holes. It is sufficient that only the proximal cortex of the lamina is opened up by drilling. It is shown in FIG. 1 that the bone openings are made before the fusion is established but this is not necessary, the openings may also be drilled after the fusion is established. Subsequently in each bone opening a suture anchor is fixed 7. Thereby it is important that the anchors used can be fixated unicortical. The anchors may be fixed by liquefying a thermoplastic material of the anchors using oscillation. The liquefied material is displaced into the pores of the surrounding bone. Therefore, the bone opening can be shorter than the anchor. During fixation the anchor shortens depending on the amount of thermoplastic material liquefied. Therefore, the user may adapt the length of the anchor after implantation to the individual vertebrae and circumstances. The anchor has enough strength for the bracing also in case that it is fixed only in an opening of minimal length (1.5-3 mm). It is suitable to use very small anchors such as the SportWelding® Fiji Anchor®.
[0098] FIG. 3 shows a schematic view of the sixth thoracic vertebrae cut in transverse plane. In the vertebrae shown in FIG. 3 a) the lamina arcus vertebrae on the left side has two bone openings 6. Furthermore, a suture anchor 16 before implantation is shown. The lamina arcus vertebrae on the left side shows two anchors after fixation (not shown are the sutures of these anchors). One can see that the liquefied material 21 of the anchors has been filled the pores of the cancellous bone within the lamina arcus vertebrae. This ensures the strength of the anchoring. The width d of the lamina arcus vertebrae as shown in FIG. 3 b may be smaller than the length e of the anchor (d<e). In particular d may be between 4 to 5 mm and e around 7 mm. The opening used to implant the anchor is preferably even less than the width d. Therefore, the method of the present invention is able to protect the spinal cord because the distal cortical end of the lamina arcus vertebrae 22 stays intact (the bone openings 6 are no blind holes). This enables to treat also fragile vertebrae or vertebrae with small laminas (cervical spine) using the method of the present invention.
[0099] In the last step the bracing is finalized by knotting the sutures 10. Therefore, the suture ends of two anchors being located in opposite openings on neighboring vertebrae are linked by two knots. This results in two double stranded links for each lamina arcus vertebrae. The strands or knotted sutures 7 of one pair of anchors run essentially parallel to each other.
[0100] FIGS. 2 illustrates the method according to aspect 1 of the present invention. Said method refers to a method of laminotomy or laminectomy. Shown is exemplarily a lumbar vertebrae 20. In a first step the muscle insertion or the muscle origin 11 (depends on the vertebrae to be treated) of the autochthonous back muscles at the spinous process 12 are cut. It may be that only one origin or respectively insertion has to be cut to get enough space to reach the basis of spinous process and the area of the lamina arcus to be treated. Deepening on the vertebrae it may also be that more than one muscle inserts or origins 11 at the respectively spinous process 12 and has to be cut. In FIG. 2a) is shown that the origin of the longissimus has to be cut. The cut should be as close to the bony structure as possible. The method according to the invention has the advantage that only the muscle insertion/origin of one side has to be cut. Thereafter (FIG. 2b) the muscles filling up the groove on the side of the spinous processes of the vertebrae (here the multifidus muscle consisting of a number of fleshy and tendinous fasciculi) can be pushed so that it is possible to cut away the spinous process 12 at its basis or transition to the lamina arcus vertebrae. The cut 13 at a frontal or coronal plane of the vertebrae separates the spinous process from the vertebrae. Said cut 13 allows to pushes away the spinous process 12 together with the muscles attached thereto. In the subsequent step (FIG. 2c) a partial resection 14 of the lamina arcus vertebrae is carried out. This partial resection may be enough to result in the wanted decompression of the spinal cord. Nevertheless, it may be necessary to introduce a tool 15 which allows to ablate degenerative alterations, such as osteophytes within the foramen vertebral (decompression of the spinal cord) or the foramen intervertebral (decompression of the spinal nerves and arteria vertebral).
[0101] Thereafter (step shown in FIG. 2d) the spinous process may be relocated and fixed to the vertebrae. It is preferred to use a plate 17 made of biodegradable absorbable material which is fixed using two pins or anchors 16 made of thermoplastic material. These pins 16 can be liquefied using oscillation. As described for the anchors above the liquefied material invades in the porous structures of the cancellous bone and thus anchors the plate. The plate has to be fixed to traverse the cut 13 of the spinous process but does not need to reach the partial resection of the lamina arcus vertebrae.
[0102] In the following step at least one suture anchor 7 has to be placed within the spinous process. It may be that more than one anchor is necessary or at least suitable e.g. in case that more than one muscle insertion or origin has been cut on the respective side of the spinous process. It is preferred that the anchor is set in a way that it is within the area of the muscle origin or insertion of the muscle to be fixed. In this case the muscle can be fixed directly to the bone which is infringed by the opening which is a suitable stimulus for recruitment of reparative cells and genes. Therefore, it is helpful for the reattachment of the muscle that the anchor is placed directly within the area of muscle insertion or origin. This should be possible also for narrow spaces because the anchors are short and can be set within a bone opening being even shorter, see FIG. 3.
[0103] One end of the suture of the suture anchor 7 is threaded through the muscle insertion or origin not cut off from the spinous process and the second end of the suture is threaded through the tendon or of the muscle or the muscle itself which has been cut off from the spinous process. With the help of the suture ends the muscle that has been cut can be pulled back to the spinous process and can be attached to the spinous process and the corresponding muscle on the other side of the spinous process. Finally, the ends of the suture are knotted as shown in FIG. 2g). The knot 19 of the suture is located on the tendinous insertion or origin of the muscle respectively on the dorsal side of the muscle.
[0104] FIG. 2f) shows an optional step of the method. In addition, to the reattachment of the muscle to the bone and the corresponding muscle of the other side using the suture of the suture anchor 7 it may be suitable to use an additional suture 18 reattach the muscle to the corresponding muscle of the other body side. This is done by simple stitching to sew the muscle being cut off to the corresponding muscle which stayed on the spinous process.
[0105] FIG. 4 shows an exemplary embodiment of the suture anchor according to the invention, which is especially designed to be used within the methods according to the invention. This suture anchor 24 include a material having thermoplastic properties (liquefiable material) or is preferably made of such a material and can be anchored in a hard tissue opening 25 by in situ liquefaction of at least part of the material having thermoplastic properties and by making the liquefied material to flow into the hard tissue to constitute, when re-solidified, a positive fit connection between the anchor and the hard tissue 21. The anchoring method on which the anchors according to the invention are based is disclosed e.g. in the publication U.S. Pat. No. 7,335,205 the disclosure of which is enclosed herein in its entirety. According to this method, a proximal face 26 of the anchor is contacted with a tool 31 which transmits energy into the anchor, in particular a vibration tool which transmits vibrational energy. Simultaneously the anchor can be pushed into a hard tissue opening.
[0106] Furthermore, the suture anchor according to FIG. 4 includes at least one distal suture conduit 29 (e.g. distal groove, channel, or eyelet) in which the suture is held when the suture anchor is positioned relative to the hard tissue opening and fixated therein, e.g. by collapsing the suture conduit and such braking or clamping the suture threaded there through.
[0107] The suture anchor 24 as shown in FIG. 4 includes a pin portion and advantageously a head portion 28 and is shown attached to a tool 31, by e.g. a press fit connection between a tool protrusion reaching into a recess in the head portion. At least the pin portion includes at least at parts of its lateral surfaces the material having thermoplastic properties. The head portion 28 may also include a suture channel 27, for example including a through opening. The suture 22 is preferably threaded there through and through the groove 29 in a way that the suture 22 can be adjusted after positioning of the suture anchor within the hard tissue opening 25. After adjustment of the suture length and/or the suture tension the suture can preferably be fixated without a knot, e.g. by collapsing the suture conduit or channel during liquefaction of the thermoplastic material.
[0108] The head portion 28 of the suture anchor may consist of one or two or more process(es), especially protruding laterally at a proximal position, having a channel for the suture 22. According to an option, the head portion is formed by a circumferential flange that has one or two (or possibly more) of the channels being through openings.
[0109] The process may be located out of the hard tissue opening 25, especially proximally thereof. This allows that the suture 22 is prevented from direct contact with the bone tissue around the opening—it may for example rest on the process after fixation. This measure serves for preventing damage of a friction sensitive suture. The rim of the hard tissue opening can be rather sharp. During movement of the spine by the patient the forces affecting the suture are high. Therefore, the suture may be damaged when rubbing on the wall of the hard tissue opening. In addition, the head portion may be used to clamp, to position or to fix an artificial tissue 32.
[0110] The pin portion may include two suture grooves 29 running across the distal pin face so that the suture 22 can be threaded as a loop 23. In axial direction, the suture can further run along one or along two opposite anchor sides.
[0111] The head portion 28 has a larger cross section than the distal end of the hard tissue opening 25 such that, when the anchor is positioned within the opening, the head portion or at least one process of the suture anchor at the proximal face protrudes beyond the proximal end of the opening at least on those side or two sides on which the suture 22 reaches this proximal anchor face.
[0112] For fixating a suture 22 relative to hard tissue 21 using the anchor as illustrated in FIGS. 4 and 5, a hard tissue opening 25 is provided. The pin portion 24 of the anchor, which is attached to the tool 31 being coupled to an energy source (preferably vibration source), is positioned into the mouth of the opening 25, the suture to be fixated by the anchor running through the suture grooves 29 and extending out of the hard tissue opening through channel 27 of the anchor head. A force is then applied to the suture anchor via the tool, the desired suture tension is established and the energy source is activated (tool and anchor vibrated). Where in intimate contact with the hard tissue wall of the opening the material having thermoplastic properties is liquefied and penetrates into the hard tissue. At the same time the anchor is pushed further into the opening and is finally anchored when the head portion 28 abuts the hard tissue surface. Only at the very end of the anchoring process, shown in FIG. 5, the suture is fixated by liquefaction of the thermoplastic material of the suture anchor. This means that the suture remains slideable (possibly against some friction between suture and tissue inside the hard tissue opening) relative to the anchor during an initial part of the fixation step and therefore the suture tension can still be adapted or maintained up to when the anchor is very close to its final fixated position.
[0113] The anchor as illustrated in FIGS. 4 and 5 may include a distal end having a smaller cross section than the rest of the anchor. It may include two eyelets 29 (suture grooves. The suture 22 to be fixated and locked with the aid of the anchor is threaded through the two eyelets 29 and runs along the anchor length e.g. in a suture groove.
[0114] The anchor can be fixated in a hard tissue opening 25, wherein the distal anchor end including the two eyelets 29 is made to collapse by the suture being tensioned against the anchor and/or by pushing it against the hard tissue on the bottom of the opening 25 provided for the anchor. The collapse can also be provided by the liquefaction of the thermoplastic material using vibrational energy introduced by tool 31. Such collapse locks the suture 22 because the diameter of the suture eyelet or groove is reduced in such a manner that the suture cannot slide there through anymore.
[0115] FIGS. 4 and 5 show, in a very schematic manner, the anchor before and after the fixation of the anchor. In FIG. 4 the anchor is attached to the distal end of the tool 31 is positioned in the mouth of the hard tissue opening 25, the suture 22 runs through the two eyelets 29 and out of the opening 25 at one side of the anchor. Not shown is that the tool is activated by the not shown energy source and the anchor is pushed further into the opening 25. Then the suture 22 can be tensioned or the suture tension be increased. In FIG. 5 fixation of the anchor and locking of the suture 22 are complete. Up to the moment of the collapse of the eyelets 29 r the lateral suture groove, the suture 22 may remain slideable relative to the anchor.
[0116] FIGS. 6a and 6b illustrate a further exemplary embodiment of the anchor according to the invention. FIGS. 6a and 6b show, in a very schematic manner, the anchor before and after the fixation of the anchor. According to this embodiment, the suture anchor 24 includes an inner cavity 33 for insertion of an element made of thermoplastic material. A suture 22 is retained by the anchor, e.g. by being threaded through a distal eyelet 29 or groove. The suture anchor is positioned and/or fixated in a hard tissue opening or is forced into the hard tissue opening with the aid of a pusher tool (not shown) and is held in the hard tissue with the aid of this tool, which may include a distal tool end adapted to fit into the inner cavity 33 or to be cannulated and fit to the sleeve 34, which in this case is able to transfer vibration of the tool to the anchor and the inserted thermoplastic material 35. In an intermediate step, the suture tension is then adjusted or the suture shortened by rotating the suture anchor around its axis with the aid of a tool, while holding the suture 22 such that the suture is wound around the anchor. When the suture tension is satisfactory, the anchor is secured in the hard tissue with the aid of a thermoplastic pin 35 inserted into the inner cavity 33 of the anchor. This inner cavity has at least one opening for releasing the liquefied material or is connected with the circumferential surface of the suture anchor by passages. This opening may be positioned lateral or at the distal end. The winding of the suture around the suture anchor is suitable to adjust the tension of the suture.
[0117] The suture anchor includes a sleeve 34. The axial channel of the sleeve has preferably a cross section adapted to the cross section of the inner cavity 33 of the anchor. The sleeve has two channels 27 for the suture. By threading the suture trough these channels and the sleeve friction between the suture and the hard tissue are minimized, also after implantation of the anchor, when the patient is moving again and high forces are affecting the spine and therefore also the suture. The sleeve may include one or two processes overlying the rim of the hard tissue opening. In this case, the suture is lying on the material of the sleeve not directly on the hard tissue.
[0118] In an intermediate phase (not shown) the anchor is pushed into a hard tissue opening or, by impaction, into the hard tissue, the suture 22 possibly remaining slideable through the eyelet 29. The suture tension is adjusted by rotation of the anchor, the suture 22 being suitably held such that it is wound around the suture anchor, wherein the latter, for accommodating the wound suture, may include a waist-like area of a reduced cross section. The wound suture is therewith tensioned and at least temporarily locked relative to the anchor and relative to the hard tissue. Thereafter a thermoplastic pin 35 is introduced into the inner cavity 33 of the anchor, as well as the sleeve. For the securing step, the material of the thermoplastic pin 35 is liquefied by a tool introducing mechanical (vibration) energy and pressed through the passages 36 to penetrate the hard tissue surrounding the anchor. FIG. 6b shows the suture anchor after fixation in the hard tissue and after removal of the tool.
[0119] The design of the inner cavity 33 of the suture anchor and of the passages 36 relative to the system of channels and/or grooves for retaining the suture are dependent on the individual purpose. The suture anchor may include passages 36 with outer mouths positioned in the anchor area around which the suture 22 is wound. This means that the suture 22 will get into contact with the liquefied material and will be surrounded by it, which, on re-solidification, will not only secure the suture anchor relative to the hard tissue but also the suture relative to the suture anchor. Alternatively, the mouths of the passages 36 may be situated more distally than the anchor area where the suture is situated on the outside of the suture anchor and in particular where it is wound around the suture anchor.
[0120] FIG. 7 and FIG. 8 show a schematic view of a suture anchor according to the invention. FIG. 7 shows a longitudinal section of the anchor 24 within an opening 25 in a hard tissue 21. FIG. 8 shows a schematic top view of the suture anchor according to FIG. 7. The anchor 24 includes a pin, a head portion 28 in the form of a process and a suture 22. The suture 22 runs laterally around the pin. Therefore, the pin may include a suture groove 29 running across the distal pin face and, in axial direction, along two opposite pin sides. Preferably, the overall cross section of the suture groove is adapted to the suture or sutures to be locked with the aid of the anchor such that the suture(s) running along the groove does not protrude from the groove, i.e. does not get into contact with the hard tissue when the anchor is pushed into the hard tissue opening provided therefore.
[0121] The anchor head includes a channel 27 where the suture 22 should be threaded through. The process of the head portion 28 is formed to rest on the outside of the hard tissue 21. This helps to protect the suture 22 that runs over the anchor material but has no contact to the hard tissue surface and especially not to the rim of the opening 25 in the hard tissue. Therefore, friction acting on the suture after implantation (during movement of the spine) can be reduced. Therefore, it is preferred that the rim of the channel 27 is smooth and that also the material of the process is chosen to lower friction (smooth surface). The head portion has a larger cross section than the distal end of the anchor and the opening in the hard tissue such that, when the anchor is introduced into the opening, the proximal face of the head protrudes beyond the proximal end of the opening at least on one side on which the suture groove reaches the head. The channel 27 within the head may be located to extend the suture groove. Alternatively, the head portion can be attached to the pin portion of the anchor such that it is rotatable in order to position the channel to be in line with the suture (groove).
[0122] Depending on the method or the location of the anchor according to FIGS. 7 and 8, the head portion includes one or two process having each a suture channel. In case that, after implantation, both ends of the suture should run into the same direction one process is sufficient, wherein on the opposite side the suture groove 29 ends at the proximal face of the anchor (shown in FIG. 8). It is also possible that the suture runs in two different directions (to two adjacent vertebrae, cf. FIG. 9). In this case, the head may include two processes 28 and two channels 27 so that each end of a suture can be positioned on a process.
[0123] FIG. 9 illustrates the method according to aspect 2 of the present invention wherein the tension band wiring is used to stabilize more than two neighboring vertebrae 21. In particular in this case, it may be helpful to use suture anchors 24 allowing to tension the suture (knotless) after introduction into the bone opening 25. Consequently, the method for spine stabilization includes a first step wherein at least one suture anchor per lamina arcus vertebrae or per pedicle of at least three adjacent vertebrae is positioned, subsequently the suture is tensioned. Before tensioning of the suture there may be a suture loop 23 between each suture anchor, which allows winding the suture around the anchor for adjusting the suture tension. Thereby it is possible to differ the tension on each side of the vertebrae and adjust the tension to the need of the patient. Subsequently, the anchor is fixed in the bone opening and the suture is fixed (e.g. by liquefaction and re-solidification of a thermoplastic material) relative to the suture anchor. This can be done in parallel (one step) or in subsequent steps, wherein the chronological order can vary and depends on the suture anchor design or the individual demands. Finally, the suture ends of two anchors located at corresponding locations in vertebras being furthest away are knotted together. FIG. 10 shows a schematic top view of a suture anchor according to the invention similar to the one of FIGS. 7 and 8 and being suitable for the method as illustrated in FIG. 9. The head portion includes two processes 28, each having a channel 27 for the suture. Therefore, it is possible that the suture ends of one suture anchor run in two different direction (to two adjacent vertebrae, cf. FIG. 9) after anchoring. Each suture end rests on one process so that friction is reduced. The suture anchor may include a recess 26 or a protrusion 26 to fit to a distal end of a tool used to introduce the anchor, to rotate the anchor and or to introduce mechanical energy into the anchor (such as vibrational energy) for liquefaction of a thermoplastic material. The dotted line 30 indicates the contour of the anchor pin portion. The head portion and the pin portion of the suture anchor may be made as one piece or may be made as two pieces, wherein the head may be configured as a sleeve sitting on the pin portion or may be formed as a plate or disc being attached to the pin portion. This plate or disc may be rotatable in respect to the pin portion of the suture anchor. Therefore, the plate or disc may be introduced into a circumferential furrow or notch of the pin portion.
[0124] FIGS. 11a and 11b show a suture anchor that has a suture anchor body (forming the pin portion 24) and additionally a disc or plate 41 held relative to the body by being received in a disc retaining groove 42. The disc or plate 41 includes the channels 27 for the suture 22 and is rotatable relative to the body. In this way, the disc or plate 41 protects the suture from contact with the rim of the opening in the bone tissue like in the embodiments of FIGS. 4-6 and nevertheless allows a tensioning of the suture by definition the rotational position of the pin portion—more in general the orientation of the pin portion and the channels 27 can be chosen independently due to the plate or disc 41 being rotatable relative to the pin portion—similarly to the principle illustrated referring to FIG. 6.
[0125] The channels may include through openings through the disc or plate or may include notches, for example facing inwardly towards the suture anchor body.
[0126] FIG. 12 shows an embodiment similar to the embodiment of FIG. 6 (and implementing a suture tensioning-by-rotation principle described in detail in WO 2012/100359/EP 2 667 790), but with a plate or disc 41 of the kind described referring to FIG. 11a/11b instead of a sleeve.
