WO2023021165A1

WO2023021165A1 - Method and kit of parts for surgical correction of spinal deformities

Info

Publication number: WO2023021165A1
Application number: PCT/EP2022/073133
Authority: WO
Inventors: Alex Kristian ROTH; Remco Johannes Petrus DOODKORTE; Paulus Cornelis Petronella Hubertus WILLEMS; Lodewijk Willem Van Rhijn
Original assignee: Dsm Ip Assets B.V.; Academisch Ziekenhuis Maastricht; Universiteit Maastricht
Priority date: 2021-08-19
Filing date: 2022-08-18
Publication date: 2023-02-23

Abstract

A method of affixing a spinal rod to a vertebra and a kit of parts to be used in said method are provided. The method comprises providing a length of tape, which length of tape has a knotted portion tied around a hollow support body in a slidable knot. By passing the ends of the tape underneath the lamina of the vertebra, and subsequently passing the ends of the tape through the hollow support body, the knotted portion of the length of tape may be slid from the hollow support body towards the vertebra. Because the slidable knot is tied onto the hollow support body, chance of errors in the knot may be reduced. The kit of parts provides the hollow support body (202) and the length of tape (104).

Description

METHOD AND KIT OF PARTS FOR SURGICAL CORRECTION OF SPINAL DEFORMITIES

CROSS-REFERNCE TO RELATED APPLICATIONS

This application is an international application claiming priority to European Patent Application No. EP21192104.4, filed 19 August 2021.

TECHNICAL FIELD

The invention relates to the field of surgical correction of the spine by affixing rods to the spinal column.

BACKGROUND

Scoliosis is a three-dimensional deformity of the spine that can be caused by neuromuscular or syndromic pathology, spinal degeneration or congenital disorders, but most commonly scoliosis occurs in an idiopathic manner. The treatment of this spinal deformity can be non-surgical by exercises or bracing of the spine during growth. However, when the curve of the spinal deformity progresses or causes pain, immobility and neurological deficits, surgical correction of the spine is indicated. In spinal fusion surgery, two metal rods are affixed to the spinal column, predominantly by pedicle screws.

Alternative components to anchor the metal rods to the spine are also routinely used, such as sublaminar wires, cables or tapes and laminar hooks. These alternative components may be used when semi-rigid spinal fixation is preferred over rigid spinal fixation.

WO2014151416 discloses a polymeric sublaminar tape system comprising a pliable lead to facilitate sublaminar insertion. A longitudinal member is flexible relative to the lead. The longitudinal member extends between a first end connected to the lead and a second end defining an opening configured for movement of the lead through it, thus creating a sliding knot. The pliable lead is removed and disposed as waste. One challenge when treating scoliosis is compensating for the remaining natural growth of the patient throughout treatment. A technique has been developed with which the metal rods are not rigidly fixed to the spinal column, but allow for sliding motion such that the spinal column has freedom of movement along the longitudinal direction of the metal rods. This technique is discussed in Bogie R, Roth AK, de Faber S, de Jong J J, Welting TJ, Willems PC, Arts JJ, van Rhijn LW. Novel radiopaque ultrahigh molecular weight polyethylene sublaminar wires in a growth-guidance system for the treatment of early-onset scoliosis: feasibility in a large animal study. Spine (Phila Pa 1976). 2014 Dec l;39(25):E1503-9. doi:

10.1097 /BRS.0000000000000637. PMID: 25417826.

One way of accomplishing this movement is by the use of knotted sublaminar tape. Although the technique has been proven to be effective, the handling of materials and tying of knots is cumbersome and time consuming. Kits of materials and methods that increase the ease of use and reduce the time of surgery are desirable.

US2019/0282283 discloses a method for providing a bone cerclage including wrapping suture around a bone, tensioning the suture to tighten the suture relative to the bone, and securing the suture to the bone.

SUMMARY

It is preferred to affix spinal rods, such as metal rods, to the spinal column in a safe, reliable and/or more practical manner. A tape with a rectangular cross-section may be used to affix a spinal rod to the spine. Such tapes may be preferred relative to, e.g., yarns with a circular cross-section. This is because of the reduced prominence of the tape that may be achieved and/or an increased bone contacting surface, avoiding peak pressures, thus preventing or reducing the risk of the tape from cutting into the lamina. Tapes formed from polymer fibers and/or yarns may be desirable for their strength. However, such tapes are often slippery and can present challenges in handling and in achieving a stable knot. The inventions disclosed herein may present advantages in handling such polymer tapes and in the overall operative procedure. For example, it may be preferred to reduce the number of steps required to affix a spinal rod to the spine, and/or the chance of errors may be reduced.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows a length of tape wrapped around a hollow support body;

Fig. 2 shows the tape and hollow support body of Fig. 1 with an additional knot tied into the tape;

Fig. 3 shows joined ends of the tape prior to being passed through the hollow support body;

Fig. 4 shows the joined ends of the tape passed through the hollow support body and the slidable knot slid from the hollow support body;

Fig. 5 shows one spinal rod affixed to a spine using knotted tapes;

Fig. 6 shows a particular embodiment of a hollow support body; and Figs. 7A-7C schematically depict different embodiments of a malleable leader connected to a length of tape.

DETAILED DESCRIPTION

In an embodiment, a method for affixing a rod to the vertebra of a human or animal is provided. The method comprises the steps of providing a length of tape, which length of tape has two ends and which length of tape has a knotted portion tied around a hollow support body in a slidable knot, passing the ends of the tape under the lamina of the vertebra, subsequently passing the ends of the tape through the hollow support body, sliding the knotted portion of the length of tape from the hollow support body away from the ends of the length of tape and/or towards the vertebra, sliding the hollow support body over the ends of the length of tape to remove the hollow support body, positioning a spinal rod, e.g. a metal rod, between the knotted portion of the length of tape and the vertebra, and tensioning the knot in the knotted portion for affixing the spinal rod to the vertebra. By affixing the spinal rod to the vertebra using this method, a semirigid fixation may be obtained. The semi-rigid fixation may be preferred over a fully rigid fixation for example in patients with adult degenerative scoliosis, and/or may allow growth in case of a growth-guidance system, for example for the treatment of early onset scoliosis.

A spinal rod is a surgical device most often made of stainless steel, cobalt chromium, or a titanium alloy. In general, two metal rods are fixed to the spinal column. A spinal rod, such as a metal rod, may be pre-shaped to correspond to a desired trajectory of patient correction or growth.

The hollow support body may have a substantially smooth outer surface to allow convenient sliding of the tape from the hollow support body. By pre-creating the knot on the hollow support body, a higher consistency of the knot can be obtained, for example since warped or twisted cable strands can be more easily avoided compared to a knot made manually in the operating room without any support body.

A slidable knot may generally be defined as a knot which can slide over a strand of tape around which the knot is made. When a slidable knot is used to form a loop in a length of tape, sliding the slidable knot may reduce the length of tape in the loop. In a particular case, a slidable knot is only slidable in a single direction. This may prevent the knot from loosening, i.e. lengthening of tape inside the loop. A slidable knot may be a friction knot, which grips the tape when a force is applied to it and is free to move when the force is released. This force may be directed towards the ends of the tape - i.e. away from the slidable knot. In general, a slidable knot may be any friction hitch.

A knotted portion of tape may generally be defined as a part of the tape in which a knot is formed, either loose or tightened. A knotted portion may hence comprise a knot such as a slidable knot. For tensioning the knot in the knotted portion, manual force may be used, for example applied by a surgeon. Additionally, or alternatively, a tensioning tool may be used which may be set to apply a particular tensioning force. As a particular option, for forming the knotted portion tied around the hollow support body in the slidable knot, the following steps may be performed: forming a loop at a distance from both ends of the tape, optionally laying the loop over the hollow support body, wrapping the length of tape around the hollow support body, and passing the ends of the tape through the loop. This particular knot may be or resemble a Klemheist knot, with one, two, three or more turns around the hollow support body.

Wrapping the ends around the hollow support body may result in two parts of the length of tape to be wrapped around the hollow support body simultaneously. In general, the length of tape may be wrapped around the hollow support body any number of times, for example once, twice, three times, or more. Additional turns provide additional friction, potentially resulting in a more secure knot.

In general, the knotted portion tied around the hollow support body in the slidable knot may have been formed prior to or after passing the ends of the tape underneath the lamina of the vertebra. It has been observed that creating the slidable knot after passing the ends of the tape underneath the lamina of the vertebra may be cumbersome and/or may hinder the creation of a knot without twisting the tape.

Prior to or after passing the ends of the tape underneath the lamina of the vertebra, a knot, in particular a half hitch knot, may be tied between the two ends of the tape. This knot may be used to secure the slidable knot in the length of tape, for example after the spinal rod has been positioned between the knotted portion of the length of tape and the vertebra.

In an embodiment, the ends of the tape are free ends, being unsecured to any other portion of the length of tape, such as the other end. In an embodiment, the ends of the length of the tape are joined together. Being joined together may mean that the ends are connected at or near their outer ends. In an embodiment, the ends are joined together by, for example, being stitched or glued together. When the tape has an approximately flat shape, the two ends may be joined together at their top or bottom surfaces. In an embodiment, the ends are jointed together via a malleable leader. In an embodiment, a malleable leader may be sandwiched between the ends of the length of tape or otherwise connected to each of the ends of the tape. Alternatively, one of the ends of the tape may be sandwiched between the malleable leader and the other of the ends of the tape.

The malleable leader may comprise or consist of one or more materials that allow the shape of the leader to be manipulated, for example by hand by the surgeon. After being manipulated, the shape of the leader may remain substantially the same, implying that the leader may be plastically deformed in a desired shape. For example, in use, the malleable leader may be curved to allow easier passing of the ends of the tape underneath the lamina of the vertebra without touching the spinal cord.

By sandwiching the malleable leader between the two ends of the tape, the local thickness at the ends of the tape may be equal to two times the thickness of the tape plus the thickness of the leader. A low thickness of the ends may be desired considering that the ends of the tape are passed underneath the lamina of the vertebra.

In another embodiment, each of the two ends of the tape is secured to the thickness of the malleable leader. In this way the prominence of the leader-tape construction may be no thicker than either the thickness of the leader or the thickness of two tapes. The thickness of the tape may be secured to the thickness of the leader with, for example, an adhesive.

In an embodiment, the tape is a polymer cable. A polymer cable is a cable comprised of one or more polymers. In an embodiment, the polymer cable comprises polyethylene. In an embodiment, the polymer cable comprises polymer fibers. A fiber is a long continuous filament. In an embodiment, the polymer cable consists of polymer fibers. In an embodiment, the polymer cable comprises a braid of a plurality of strands of individual polymer cables or fibers. In an embodiment, the polymer cable comprises a braid that comprises a hollow tubular braid, a solid circular braid, a spiroid braid, a flat braid, a core-sheath (sometimes called kern-mantle or core-shell') braid, or a braid- on-braid. A braid-on-braid is a core-shell construction in which a braided core is covered by another braided construction. In an embodiment, the polymer cable comprises a yarn. A yarn is a continuous strand of multiple, usually twisted, fibers. In an embodiment, the polymer cable comprises a braided, knitted, or woven cable, wherein the polymer cable comprises polymer fibers. In an embodiment, the polymer cable comprises a monofilament or a multifilament yarn. The yarn may in addition comprise other components or additives that provide some extra functional effect, such as antimicrobial or anti-inflammatory action, knotting performance, or visual contrast. In an embodiment, the polymer cable comprises a radiopaque agent.

The tape may comprise or consist of ultra-high-molecular-weight polyethylene, any other thermoplastic polyethylene, or any other high yield strength material suitable to be implanted into a human or animal body. Dyneema Purity® Radiopaque fibers may be used for forming the tape.

In general, the tape may have a non-circular cross-section, for example approximately resembling a rectangle. For example, the tape may be a flat tape, wherein in a cross-sectional view, a ratio between the height and the width of the tape is less than 1, less than 0.5, or even less than 0.2 or less than 0.1. A flat tape may have the advantage that it is less thick, and hence easier to pass underneath the lamina of the vertebra.

A second aspect provides a kit of parts for affixing a spinal rod to a vertebra of a spine of a human or animal. The kit of parts comprises a length of tape with two ends, and a hollow support body with a passage through the support body, wherein the two ends of the length of tape are arranged to be passed through the passage of the support body.

The passage of the support body is hence sufficiently large to accommodate the two ends of the tape. The passage may even be sufficiently large to accommodate the two ends with a malleable leader sandwiched between the two ends.

In the kit of parts, the length of tape may have a knotted portion tied around the hollow support body in a slidable knot. The knotted portion may have been made in a production process, and an end user such as a surgeon may as such not need to make the slidable knot themself. As an option, the hollow support body may comprise a flange. The flange may extend from an outer surface of the hollow support body and may prevent the slidable knot from sliding from the hollow support body during surgery. This in turn may aid a user in sliding the slidable knot from the hollow support body in the correct direction.

When the hollow support body comprises the flange, the hollow support body may further comprise a protrusion protruding from the flange, for example in a direction approximately parallel to an elongation direction of the hollow support body. The protrusion may further prevent the slidable knot from sliding from the hollow support body, as the tape may hook behind the protrusion.

When the hollow support body comprises the protrusion, the protrusion may comprise a thickened section at or near a distal end of the protrusion, which thickened section extends towards the hollow support body. The slidable knot may be positioned between the flange and the thickened section before use. The thickened section may then prevent the slidable knot from sliding from the hollow support body. An additional force may be required to slide the slidable knot beyond the thickened section. The thickened section may abut the outer surface of the hollow support body, and the protrusion may be bent away from the outer surface of the hollow support body to allow the slidable knot to slide beyond the thickened section.

A third aspect provides a method of preparing a slidable knot for use in a method of affixing a spinal rod to a vertebra of a spine of a human or animal, for example prior to a surgery. As such, the method maybe performed in a sterile environment and/or components such as the length of tape and the hollow support body may be sterilized.

This method comprising the steps of providing a length of tape, which length of tape has two ends, forming a loop with the tape from a portion of the tape between the ends of the tape, wrapping the length of tape around the hollow support body, and subsequently passing the ends of the tape through the loop, thereby forming a knotted portion. It will be appreciated that options disclosed in conjunction with the first aspect may be readily applied to embodiments of the second aspect, and vice versa. For example, the kit of parts of the second aspect may be used in performing the method according to the first aspect. Aspects disclosed in conjunction with the first method may be readily applied to the method according to the third aspect, and vice versa.

Fig.l schematically depicts a kit of parts 200 for affixing a spinal rod to a vertebra of a spine of a human or animal. The kit of parts 200 comprises a length of tape 104 with two ends 106, 108, and a hollow support body 202 with a passage 204 through the hollow support body. The passage 204 is dimensioned such that the two ends 106, 108 of the length of tape 104 may be passed through the passage 204, in particular together.

In Fig. 1, the kit of parts 200 is depicted in a state in which the length of tape 104 has been provided and a loop 114 has been formed with the tape from a portion of the tape between the ends 106, 108 of the tape. Furthermore, the ends 106, 108 have been wrapped around the hollow support body 202, and the ends 106, 108 have been passed through the loop 114. In particular, the ends 106, 108 have been wrapped around the hollow support body 202 two times in the example of Fig. 1.

Fig. 2 schematically depicts the kit of parts 200 in a state wherein an optional half hitch knot 116 has been tied into the length of tape. Furthermore, the slidable knot 111 has been tightened with respect to the state shown in Fig. 1.

Fig. 3 schematically depicts the kit of parts 200 in a state wherein the ends of the tape have been joined together to form joined end 120. Furthermore, the end 120 has been passed underneath the lamina 112 of the vertebra 102, e.g. through the vertebral foramen.

To assist in passing the end 120 underneath the lamina 112 of the vertebra 102, a malleable leader 118 has been sandwiched between the outer ends of the length of tape. Between being passed underneath the lamina 112 and being passed through the hollow support body 202, the shape of the malleable leader 118 may be manipulated, e.g. straightened. It may be preferred to bend the malleable leader 118 into a generally C-shape to facilitate passage through the vertebral foramen, i.e. the sub laminar passage. However, in the generally C-shape, it may not be possible to pass the malleable leader through the hollow support body, and as such, straightening may be required.

Fig. 3 depicts with dashed arrow 212 a movement path for the joined end 120 to pass through the hollow support body 202. As the joined end 120 passes through the hollow support body 202, it also passes through the slidable knot 111.

Fig. 4 depicts the kit of parts 200 after the slidable knot 111 has been slid from the hollow support body 202 towards the vertebra 102. Dashed arrow 214 indicates a direction of movement of the hollow support body 204 away from the vertebra 102. This allows the hollow support body 202 to eventually be slid over the ends of the length of tape, and subsequently removed and optionally discarded.

Fig. 5 schematically depicts a plurality of vertebrae 102. To one of the vertebrae 102, a spinal rod 300 has been affixed using a length of tape 104. In particular, the spinal rod 300 is affixed to the vertebra 102 by virtue of the slidable knot 111, which has been tensioned manually, or by using a cable tensioner device. Such a cable tensioner device may for example be used to tension the knot to a particular tension and/or for multiplying a force applied to the cable tensioner device such that a tension can be achieved which is higher than the manually applicable tension.

Fig. 6 schematically depicts a particular embodiment of a hollow support body 202, in a longitudinal section view. As an option, the hollow support body 202 comprises a flange 206 which at least partially circumferentially surrounds the hollow support body 202. As a further option, a protrusion 208 is provided, protruding from the flange 206 in a direction approximately parallel to an elongation direction or centerline 205 of the hollow support body 202. As an even further option depicted in Fig. 6, the protrusion 208 comprises a thickened section 210, extending towards the hollow support body 202.

As can be seen in Fig. 6, part of the length of tape 104 may be trapped between the flange 206 and the thickened section 210. As such, it may be prevented that the tape 104 slides of the hollow support body 202 over the side of the flange 206. Furthermore, sliding of the tape 104 of the hollow support body 202 on the other side is hampered, as first the thickened section 210 has to be bent away. This may prevent or reduce risk of accidentally sliding of the tape 104 of the hollow support body 202.

Figs. 7A-7C schematically depict different embodiments of a malleable leader 118 connected to the ends 106, 108 of the length of tape. In particular, each of the Figs. 7 A, 7B and 7C show a side or section view above a top view. In the side or section view, a thickness of the combination of the malleable leader 118 and the two ends of tape is visible. In the top view, a width of the combination of the malleable leader 118 and the two ends of tape is visible. It may be preferred to minimize the width and/or the thickness of the combination of the malleable leader 118 and the two ends of tape, as this width and thickness must be passed underneath the lamina 112 of the vertebra 102.

In the embodiment of Fig. 7 A, the malleable leader 118 comprises a slot 170, through which both ends 106, 108 can be passed. As can be seen in the section view, the thickness of the combination is defined by the thickness of the malleable leader 118 plus four times the thickness of the tape.

Fig. 7B shows an alternative embodiment of the malleable leader 118, wherein the malleable leader 118 is sandwiched between the ends 106, 108 of the length of tape. As such, the thickness of the combination is defined by the thickness of the malleable leader 118 plus two times the thickness of the tape. Alternatively, one of the ends of the tape may be sandwiched between the other end and the malleable leader 118.

Fig. 7C shows yet another embodiment of the malleable leader 118, comprising an alternative slot 172 into which one or both of the ends 106, 108 can be inserted. For connecting the one or both of the ends 106, 108, for example glue may be used, or the alternative slot 172 may be clamped onto the one or both of the ends 106, 108. The thickness of the combination of Fig. 7C may be determined by the thickness of the malleable leader.

Although in the figures the malleable leader is shown with a higher thickness than the tape, in other embodiment the thickness of the malleable leader may be equal or smaller than the thickness of the tape. The malleable leader may have a substantially constant thickness or may, for example, be at least partially tapered in a direction away from the tape.

In another embodiment, the malleable leader comprises a slot arranged for accommodating parts of the two ends of the length of tape. In particular, when the ends of the length of tape are connected to the malleable leader, the slot may partially surround the ends. The ends may be stacked on top of each other. As such, the maximum thickness of the tape and the malleable leader at the ends may be defined either by a thickness of the malleable leader, or by a thickness of the stacked ends. As such, a lower thickness may be obtained compared to embodiments wherein the maximum thickness is defined by the sum of the thickness of the malleable leader and the thickness of the stacked ends.

In general, the ends of the length of tape may be connected to each other using glue, stiches, by melting them together, by clamping them together, for example using the malleable leader, by sewing, by any other connection method, or any combination thereof. After affixing the spinal rod, the ends of the length of tape may be discarded.

A surgical method of affixing a spinal rod to a vertebra of a spine of a human or animal may be described according to the following numbered embodiments:

1. Method of affixing a spinal rod (300) to a vertebra (102) of a spine of a human or animal, the method comprising the steps of: providing a length of tape (104), which length of tape has two ends (106, 108) and which length of tape has a knotted portion (110) tied around a hollow support body (202) in a slidable knot (111); passing the ends of the tape underneath the lamina (112) of the vertebra; subsequently passing the ends of the tape through the hollow support body; sliding the knotted portion of the length of tape from the hollow support body towards the vertebra; sliding the hollow support body over the ends of the length of tape for removing the hollow support body; positioning a spinal rod between the knotted portion of the length of tape and the vertebra; and tensioning the knot in the knotted portion, thereby affixing the spinal rod to the vertebra.

2. Method according to embodiment 1, further comprising the steps of: forming a loop (114) with the tape from a portion of the tape between the ends of the tape; wrapping the ends around the hollow support body; and subsequently passing the ends of the tape through the loop, thereby forming the knotted portion (110).

3. Method according to embodiment 1 or 2, further comprising, prior to passing the ends of the tape underneath the lamina of the vertebra, tying a knot, in particular a half hitch knot (116), between the two ends of the tape.

4. Method according to any of the embodiments 1-3, further comprising, prior to passing the ends of the tape underneath the lamina of the vertebra, joining the ends of the length of tape together.

5. Method according to any of the embodiments 1-4 further comprising connecting a malleable leader (118) at or near the ends of the length of tape.

6. Method according to any of the embodiments 1-5, further comprising sliding the knot, in particular the half hitch knot, towards the joined ends (120) of the length of tape. 7. Method according to any of the embodiments 1-6, wherein the tape comprises ultra-high-molecular-weight polyethylene.

8. Method according to any of the embodiments 1-7, wherein the tape has a cross-sectional shape approximately resembling a rectangle.

In the description above, it will be understood that when an element is referred to as being connected to another element, the element is either directly connected to the other element, or intervening elements may also be present. Also, it will be understood that the values given in the description above, are given by way of example and that other values may be possible and/or may be strived for.

It is to be noted that the figures are only schematic representations of embodiments that are given by way of non-limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the disclosure may include embodiments having combinations of all or some of the features described. In the figures, the dash- dotted line indicates that the figure is cut-off, for example at the ends of the tape for conciseness of the figures.

Claims

1. Method of preparing a slidable knot for use in a method of affixing a rod (300) to a vertebra (102) of a spine of a human or animal, the method comprising the steps of: providing a length of tape (104), which length of tape has two ends (106, 108); forming a loop (114) with the tape from a portion of the tape between the ends of the tape; wrapping a portion of the length of tape around the hollow support body; and passing the ends of the tape through the loop, thereby forming a knotted portion (110).

2. Method according to claim 1, with the proviso that the method of preparing the slidable knot does not involve a surgical step.

3. Method according to claim 1 or 2, further comprising: connecting a malleable leader (118) to the ends of the length of tape.

4. Method according to any of the claims 1-3, wherein the method is performed in a sterile environment and/or the length of tape is sterilized.

5. Method according to any of the preceding claims, wherein the tape comprises ultra-high-molecular-weight polyethylene.

6. Method according to any of the preceding claims, wherein the tape has a cross-sectional shape approximately resembling a rectangle.

7. Method according to any of the preceding claims, wherein the knotted portion is moved towards a flange (206) comprised by the hollow support body.

8. Method according to any of the preceding claims, further comprising moving at least part of the knotted portion behind a protrusion (208) protruding from a flange comprised by the hollow support body.

9. Method according to any of the preceding claims, wherein the length of tape is wrapped around the hollow support body twice or more times.

10. Kit of parts (200) for affixing a spinal rod to a vertebra of a spine of a human or animal, the kit of parts comprising: a length of tape (104) with two ends (106, 108); and a hollow support body (202) with a passage (204) through the hollow support body, wherein the two ends of the length of tape are arranged to be passed through the passage of the support body.

11. Kit of parts according to claim 10, wherein the hollow support body is substantially rigid.

12. Kit of parts according to claim 10 or 11, wherein the hollow support body is not a bone.

13. Kit of parts according to any of the claims 10-12, wherein the length of tape has a knotted portion (110) tied around the hollow support body in a slidable knot.

14. Kit of parts according to any of the claims 10-13, wherein the hollow support body comprises a flange (206). Kit of parts according to claim 14, wherein the hollow support body comprises a protrusion (208) protruding from the flange in a direction approximately parallel to an elongation direction of the hollow support body. Kit of parts according to claim 15, wherein the protrusion comprises a thickened section (210) at or near a distal end of the protrusion, which thickened section extends towards the hollow support body. Kit of parts according to any of the claims 8-16, wherein the ends of the length of tape are free ends. Kit of parts according to any of the claims 8-16, wherein the ends of the length of tape are joined together. Kit of parts according to claim 18, further comprising a malleable leader, which is connectable at or near the joined ends of the length of tape. Kit of parts according to claim 19, wherein the malleable leader comprises a slot (170), through which the two ends of the length of tape can be passed. Kit of parts according to any of the claims 19-20, wherein the passage through the hollow support body is sufficiently large to accommodate the two ends together with the malleable leader. Kit of parts according to any of the claims 10-21, wherein the tape comprises ultra-high-molecular-weight polyethylene. Kit of parts according to any of the claims 10-22, wherein the tape has a cross-sectional shape approximately resembling a rectangle.

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24. Kit of parts according to any of the claims 10-23, wherein the length of tape is sterile.

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