WO2008146185A1

WO2008146185A1 - A tightening means for orthopaedic surgery

Info

Publication number: WO2008146185A1
Application number: PCT/IB2008/051740
Authority: WO
Inventors: Simon Christian Hede
Original assignee: Simon Christian Hede
Priority date: 2007-05-27
Filing date: 2008-05-05
Publication date: 2008-12-04
Also published as: DK200700157U3

Abstract

A tightening means (1';8;11;12;14;16) for use in orthopaedic surgery comprises a tie part (2) having a free end (3) and an opposing eye part (4) with an eye (5) for threading the free 10 end (3) of the tie part (2) to form a closed loop around one or more objects. The tie part (2) is provided with at least one continuous radiopaque band, strip or thread (9;9',9'a,9'b;15a, 15b,15c,15d,15e,15f,15g;17) for enabling X-ray identification. The tightening means is easy to replace and is both flexible 15 and a known degree of tensioning level and force can be applied. The tightening means is particular preferred in Luque instrumentation for surgical treatment of scoliosis and hyperkyphosis.

Description

A tightening means for orthopaedic surgery

The present invention relates to a tightening means for orthopaedic surgery comprising a tie part having a free end and an opposing eye part with an eye for threading the free end of the tie part to form a closed loop around one or more objects, such as in surgical spinal curve correction.

Various disorders require major surgical spinal curve correction. Such disorders include for example scoliosis, characterised in a lateral curvature of the spine, hyperkyphosis, characterised in an exaggerated posterior or backward curvature of the thoracic region of the spinal column resulting in a rounded upper back, and lordosis, characterised in an exaggerated forward curvature of the lumbar and cervical regions of the spinal column. More than one abnormal curvature can be seen.

Spinal instrumentation is a method of keeping the spine rigid after spinal fusion surgery by surgically attaching hooks, pedicle screws, rods, and wires to the spine in a way that redistributes the stresses on the bones and keeps them in proper alignment while two or more vertebrae combine or fuse. The skilled surgeon knows various types of spinal instrumentations. Which type of instrumentation to chose for a specific patient is selected on the basis of parameters such as the type of disorder, the condition of the patient, and the surgeons experience. US patent no. US 2008/0015577 Al discuss in detail various known surgical instrumentation methods particular suited for spinal correction.

Two major improvement of spinal instrumentation should be noted. In the Harrington procedure the surgeon uses one or more steel rods, extending from the bottom to the top of the spinal curve to support the fusion of the vertebrae. The rod is attached by means of hooks that are suspended from pegs inserted into the bone. The steel rod is jacked up and then locked into place to support the spine securely and the surgeon fuses the vertebrae together. After one to two years, the steel rod is often not necessary, but it is almost always left in place unless infection or other complications occur. [Harrington PR: Treatment of scoliosis : correction and internal fixation by spine instrumentation . J Bone Joint Surg Am 44: p. 591-610, 1962. Harrington PR: The history and development of Harrington instrumentation by Paul R. Harrington, 1973. Clin Orthop 227: p. 3-5, 1988].

In paediatric surgery the Luque instrumentation has offered a reliable but rather bulky and surgically time-consuming instrumentation in curve correction with and without fusion. A description of the Luque wire technique can be found in Luque, ER, Segmental spinal instrumentation for correction of scoliosis, Clin. Orthop. 163: p.192-198, 1982 and in Moe's Textbook of Scoliosis and Other Spinal Deformities by John E. Lonstein, David S. Bradford, Robert B. Winter, and James Ogilvie, 3^rd ed.; W. B. Saunders Comp. 1995.

The Luque instrumentation includes segmental fixation of the spine and is mainly preferred in severe neuromuscular collapsing scoliosis with limited rotation and in hyperkyphosis . To achieve multiple points of fixation and distribution of the correction forces to every spinal segment involved to thereby reduce need for external immobilization, one or more prebent metal rods are secured along the spine with segmental sublaminar metal steel wiring. The Luque instrumentation includes the possibility of adapting to curve changes by telescoping before final fusion but also involves a high risk of injury to the nerves and spinal cord, including paralysis. The Luque instrumentation is very time consuming because the wires need to be twisted by hand or with primitive tools. The wires become bulky during twisting without any possibility given to the surgeon to measure the tension of each wire. In hypertensioning of the wires there is a risk of wires cutting through the lamina while hypotensioned wires are inefficient in curve correction. Finally, in removal of Luque wires the dura may be damaged when the wires are cut and pulled out due to the spring properties and sharpness of the cut metal wires. A significant incidence of neurological complications has often been demonstrated, Wilber RG, Thompson GH, Shaffer JW, et al : Postoperative neurological deficits in segmental spinal instrumentation . A study using spinal cord monitoring. J Bone Joint Surg Am 66:1178, 1984.

In summary surgery that involve twisting of metal wires for securing bones to each other, to correction rods or plates, or any other supportive correction aid suffers from the likelihood of unintentional injuring the patient during implantation and subsequent surgical removal due to sharp edges and risk of rupture and release of spring force. Alternative means are in high demand and alternative thinking required.

A plastic cable tie is known for encircling and tightening a bundle of electric cables. The known cable tie consists of a strip part having a free end and an opposing end with an eye for threading the free end to form a closed loop around the bundle. The diameter of the loop can be reduced to tighten around the bundle by pulling at the free end. Protrusions along the tie serve as a locking means aiming to prevent unduly release of the loop after tightening, however plastic cable ties often rupture during tightening and as a result ties must be replaced. If a bundle of tied cables are in a hardly accessible place it is difficult to see if a cable ruptures and if the bundle is at risk of falling apart. To this aspect US 2007/0234525 Al discloses a cable tie, which is moulded from a composite material that includes 1% up to 20% by weight of distributed metal particles or metal flakes, a compound such as barium sulphate and a plastic carrier material. The metal particles and the barium sulphate particles enable detection by X-ray, but tensile stress at a given elongation is limited. It is a first aspect according to the present invention to provide an improved tightening means of the kind mentioned in the opening paragraph as an alternative to conventional wires for securing rods to the spine in surgical spinal curve correction.

It is a second aspect according to the present invention to provide a tightening means of the kind mentioned in the opening paragraph that can be tensioned with a minimum of injury to the surgical site, reduces surgery time, and is easier to apply than known tightening means.

It is a third aspect according to the present invention to provide a tightening means of the kind mentioned in the opening paragraph that can be tensioned in a controlled and fast manner .

It is a fourth aspect according to the present invention to provide a tightening means of the kind mentioned in the opening paragraph that is easy to remove at a given point of time during or after spinal curve correction.

It is a fifth aspect according to the present invention to provide a tightening means of the kind mentioned in the opening paragraph that can be identified by X-ray imaging diagnostics.

It is a sixth aspect according to the present invention to provide a surgical instrumentation procedure in which the complication rate is low.

In the following the term "orthopaedic surgery" means preservation, restoration and development of the form and function of the extremities, spine and associated structures by surgical and physical methods. The term "radiopaque" means having the quality or property of obstructing the passage of radiant energy, such as X-rays, the representative areas appearing light or white on an exposed film or on an X-ray screen.

The term "fusion", "fuse" or "fusion procedure" when used in spinal correction surgery means "adjoining" vertebrae's in a procedure in which a surgeon first exposes the backs of the vertebrae that lie along the curve to be corrected by slicing cortical bone. The bony outgrowths along the vertebrae's that makes the spine twist and bend are removed. Bone grafts are placed across the exposed surface of each vertebra, without touching the adjoining vertebrae not to be fused. The grafts regenerate, grow into the bone, and fuse the vertebrae's together.

The term "X-ray imaging diagnostics" when used in the present application includes any radiologic procedure for providing still or moving images, including a fluoroscopy procedure.

The novel and unique whereby the above aspects are achieved according to the present invention is the fact that the tie part is provided with at least one continuous radiopaque band, strip or thread.

The at least one continuous radiopaque band, strip or thread may be provided as one single band, strip or thread along the entire length, as several parallel bands, strips or threads having the same length as the tie part and arranged along the entire length of the tie part, or as bands, strips or threads having lengths shorter than the tie part and arranged in overlapping relationship along the entire length of the tie part .

The inventive tightening means provides an alternative and/or supplemental means to the hooks, screws, and wires that help to support the fusion of the vertebrae's in conventional spinal correction procedures. The tightening means constitutes an easy implantable device for securing implants in orthopaedic surgery. The continuous radiopaque tie part makes it very easy to place the tightening means exactly where it is intended. The entire length of the tie part can be X-ray visualized, both during instrumentation and after instrumentation to verify correct surgical placement. The closing and tensioning of the loop can also be followed using X-ray screening as well as X- ray can be used to ensure proper post surgical placement of the tightening means at any given time. X-ray of the at least one continuous radiopaque band, strip or thread provides a clear picture of the entire length of the tightening means. If the tightening means ruptures the rupture can be easy identified as a discontinuity in the radiopaque band, strip or thread. The place and degree of discontinuity provides important information to the surgeon. The surgeon can e.g. use the information for early interpreting and understanding changes in conditions at the particular part of the surgical site in vicinity of the tightening means. A ruptured tightening means may e.g. be the result of excessive stress conditions, which information can be used as an early indication that extra or substitute tightening means are required to preserve the necessary mechanical and physical securing of bones, implants and tightening means ensuring that e.g. a spine is kept in the surgically corrected position during and after healing.

The tightening means is very easy to place correct right away. When the tightening means are to be removed they are simply cut and withdrawn as one single unit. The required untwisting of the conventional Luque wires is not necessary. Only minimal invasive post surgery may be required for most patients. The surgeon can identify where to cut using X-ray and withdraw the cut tightening means through a small incision. Subsequently any rods or similar correction means can be withdrawn through another suitable incision. This kind of instrumentation and surgery is fast and induces minimal injuries and trauma to the patient. The skilled orthopaedist will appreciate and understand that the tightening means according to the present invention can be used not only in spinal instrumentation but also in any surgical procedure involving holding a fractured bone structure together or in proximity during a period of time. As an example the tightening means can be used for sternal closure after open hart surgery.

If the at least one continuous radiopaque band, strip or thread is embedded in an outer covering, preferably a biological acceptable plastic material, the insertion, implantation and later removal of the tightening means can be made smoothly without or only with minimum injuring of surrounding tissue and pain. The tightening means may be shaped with smooth edges and corners to further improve this effect. Suitable plastic materials include ultra-high molecular weight polyethylene, polyacetal resins and polyetheretherketone as suggested by Eschbach L. in Nonresorbable polymers in bone surgery. Injury, 2000 Dec; 31 Suppl 4:22-7.

During a sublaminar segmental insertion of a tightening means according to the present invention the free end is introduced and advanced through the eye part to form a loop around one or more vertebrae's and rods to fixate said parts in relation to each other for a period of time, e.g. 3 - 6 month or longer, to allow fusion and healing.

In a preferred embodiment the at least one continuous radiopaque band, strip or thread is made of a metal or a metal alloy to provide the tightening means with a high level of rupture strength during formation and tensioning of the loop and during the post surgery period. A suitable metal may be stainless steel, but any suitable metal, preferably having high rupture strength, may be embedded in the plastic material.

Metal composites are also foreseen. A suitable metal alloy is nitinol. Nitinol may also be included in a composite tightening means. At a temperature below body temperature a nitinol band, strip, or wire or thread may be straight but once subjected to body temperature the nitinol reassume any given preshape, e.g. a loop structure. This inherent property of nitinol may expedite the loop formation procedure .

In an alternative embodiment, although less preferred for some patients and orthopaedic procedures, the at least one continuous radiopaque band, strip or thread is hollow and includes an X-ray identifiable substance, such as barium sulphate. Alternatively barium sulphate is incorporated in a continuous channel. These alternative embodiments can be identified just as easy as the embodiment provided with a metal or a metal alloy part. The alternative embodiments are far more flexible but less preferred for conditions and situations in which high stress levels are inevitable due to a low rupture strength of the plastic material. However, for conditions where high bendability and flexibility is required, e.g. for very young children, who grows fast and have limited moveability, and where a lesser degree of rupture strength is acceptable the alternative embodiments may be preferred. If the alternative tightening means rupture a liquid radiopaque substance may leak. This can however easily be X-ray identified. Most likely the patient will feel the efflux indicating action to be taken.

In order to ensure that the tightening means are tightened to exactly the intended degree at least one face of the tie part may be provided with a plurality of protrusions for engaging with the eye part of a part of the eye part, optionally engaging corresponding one or more protrusions protruding inside the eye of the eye part. The protrusions engage and lock the tie part firmly inside the eye and prevent accidental reopening of the closed loop. A tensioning tool, e.g. a conventional tensioning tool for tensioning cable ties, may advantageously be used for ensuring application of a known tensioning force. Examples of conventional suitable tensioning tools can be found in e.g. U.S. patent no. US 5,386,856 and US patent no. 7,299,830. The engagement between tie part and eye can be made in any suitable known manner, e.g. a plurality of tongues and grooves. Irrespective of which kind of engagement, the continuous radiopaque band, strip or wire visualizes the entire loop structure.

The preferred and correct tensioning force may vary among patients and conditions. The tightening means can be further tensioned after implantation and during healing and fusion if required by simply pulling the free end to reduce loop diameter by engaging the eye part and a protrusion closer to the eye part. The loose free end may subsequently be cut off, either with a separate tool or using a cutter part of the tensioning tool. The tensioning tool may be adapted to apply a selected predetermined measurable force enabling the surgeon to keep a tensioning data file. This has never been possible before. The surgeon has e.g. twisted the Luque wires without knowledge of tensioning degree or value. Hence, the novel tightening means by means of which the surgeon can control applied tensioning force constitutes a landmark approach in spinal instrumentation .

A sufficient strong frictional locking engagement of the tie part inside the eye part is obtained if the diameter of the eye of the eye part is smaller than the cross section of the tie part at a given engaging part of the length of said tie part.

The tie part of the tightening device may advantageously be configured so that at least one face of the tie part has a plurality of protrusions for engaging with the eye part of a part of the eye part. This ensures locking of the loop with a predetermined degree of tension depending on which protrusion that engages the eye part. Any of the protrusions may e.g. be configured as serrations or barbs, preferably serrations or barbs protruding in an angle toward the eye part smaller than or equal to 90°, preferably smaller than 60°, and most preferred smaller than 45°, to thereby further ensure that the loop does not open by itself for example in response to patients movement. The angling of the protrusions facilitates tightening and engagement of the tie part inside the eye part. Accordingly, the angular serrations or barbs lock the loop in the desired size in a surgical safe manner. The tightening means having protrusions such as barbs or serrations is removed in a similar manner as a tightening means without serrations or barbs. First the tightening means is cut to open the loop, and subsequently the tightening means is pulled out of a small incision, e.g. in an endoscopic procedure, taking precaution that cutting and pulling is so that the angling of the serrations or barbs does not hinder withdrawal .

The invention further relates to a method of performing spinal curve correction including the steps of

- performing any of an anterior spinal approach, a posterior spinal approach or a combination of these spinal approaches to expose one or more vertebrae,

- removing outgrowths along one or more vertebrae, - placing bone grafts across the exposed surface of the one or more vertebra, inserting at least one correction rod along the patients spine, securing the at least one correction rod to one or more vertebrae's using one or more tightening means as described above, and

- tightening the tightening means to an appropriate degree.

This new method is an alternative method to known spinal curve correction methods. Due to the inventive tightening means the spinal curve correction can be performed faster and with fewer complications than seen before. The inventive tightening means allows for application of any desired tension force. A tightening means is easy to replace. It is simply cut and withdrawn, e.g. in an endoscopic procedure, and a new one can be inserted in the same procedure using the same access site and route as the previous tightening means was removed through. In this manner the inventive tightening means can easily be further tensioned or be replaced to loose tensioning. The locations and conditions of the tightening means can be identified and followed as required using X-ray.

The method is particular preferred for correcting scoliosis.

The invention will be described in further details below by way of examples of embodiments with reference to the drawings in which,

fig. 1 shows, seen in perspective, a first embodiment of a conventional cable tie,

fig. Ia shows the same but with a radiopaque, continuous band embedded in a transparent plastic material in accordance with the present invention,

fig. 2 shows, seen in perspective, a second embodiment of a conventional cable tie,

fig. 3 shows, seen from a longitudinal face, a first embodiment of an X-ray identifiable tightening means according to the present invention,

fig. 4 shows, seen from a longitudinal face, a second embodiment of an X-ray identifiable tightening means according to the present invention, fig. 5 shows a longitudinal sectional view of a third embodiment of an X-ray identifiable tightening means according to the present invention,

fig. 6 shows a longitudinal sectional view of a fourth embodiment of an X-ray identifiable tightening means according to the present invention,

fig. 7 shows a longitudinal sectional view of a fifth embodiment of an X-ray identifiable tightening means according to the present invention,

fig. 8 shows a perspective view of the embodiment shown in fig. 3 in looped and engaged condition,

fig. 9a shows schematically a normal spine seen from the back,

fig. 9b shows the same seen from the side,

fig. 9c shows schematically seen from the back an abnormal spine curvature of a patient suffering from scoliosis,

fig. 9d shows schematically seen from the back an abnormal spine curvature of a patient suffering from hyperkyphosis,

fig. 10 shows schematically a part of a spine seen from the front of the back, which spine is corrected using a conventional Luque instrumentation including rods and a few sublaminar segmental wirings for distraction and correction of the thoracic region of the spine, and

fig. 11 shows schematically a part of a spine, seen from the front of the back, corrected using corrections rods and the tightening means according to the present invention instead of metal wires. In the following the embedded radiopaque reinforcement element is a metal strip. However, the person skilled in the art will understand that other radiopaque long thin continuous elements, such as e.g. wires, threads or bands within the scope of the present invention can be incorporated instead.

The conventional plastic cable tie strip 1 seen in fig 1 has a tie part 2 having a free tapered end 3. Opposite the free tapered end 3, the tie part 2 has an eye part 4 with an eye 5. The eye 5 is made as a through-going hole through which the free end 3 of the tie part 2 is pulled for forming a closed, locked loop, as indicated by arrows B, around one or more object to be combined in a bundle (not shown) . By making the diameter d of the eye 5 smaller than the cross-section D of the tie part 2, the obtained engagement between eye 5 and tie part 2 can be made so strong that the closed loop not disengage suddenly without external interference.

Fig. Ia shows a very simple embodiment of a tightening means 1' according to the present invention. The tightening means 1' corresponds substantially to cable tie strip 1 of fig. 1 and for like parts same reference numerals are used. The tightening means 1' differs from the cable tie strip 1 in that a continuous, radiopaque band 9 is embedded in a plastic material 10, which in the case shown, is made transparent for illustrative purposes, just as in the subsequent figures. This is however not to be understood as limiting for the present invention .

The conventional embodiment of a cable tie 6 shown in fig. 2 has in addition a plurality of barbs 7 at the longitudinal face, which defines the inner circumference of the loop once formed, which barbs 7 effectively prevents disengagement once the loop has been formed. The barbs 7 hook firmly inside the eye 5 in a non-detachable manner. The only way to open the closed cable tie loop to get access to the bundled items is to cut or otherwise rupture the cable tie. One or more continuous radiopaque bands, strips, wires etc. may be embedded in the tie part 2 in the same manner as shown in fig. Ia. This configuration of barbs is however not well suited for all surgical implantations due to the barbs 7.

Seen from a longitudinal face, corresponding to the face defined by diameter D of the cable tie 1 shown in fig. 1, fig. 3 shows a tightening means 8 according to a first embodiment of the present invention. This embodiment corresponds substantially to the cable tie 1, shown in fig. 1 and for like parts same reference numerals are used. The tightening means 8 differs from the cable tie 1 in that a single continuous thread of metal 9' is embedded in a flexible transparent plastic material 10 of the tie part 2. The metal thread 9' makes is possible to identify any given location and shape of the entire length of the tightening means 8 using radiographs or fluoroscopy during and after loop formation. Inside the eye 5 of the eye part 4 a protrusion 13 serves as a locking means for the tie part 2 when passed through the eye 5. The protrusion 13 may be configured to engage corresponding protrusions (not shown) provided along and cross-wise of the face on the tie part 2. Alternatively, as described for fig. 6, the protrusion 13 is configured as a flexible hinge allowing the tie part to pass through upon deflection and, once the tie part has passed, to provide a pressure force on said tie part to ensure safe locking of the tie part 2 inside the opening 5.

The second embodiment 11 shown in fig. 4 differs from the first embodiment 8 shown in fig. 3 only in that two metal threads 9'a,9'b are embedded in the plastic material 10.

The third embodiment for at tightening means 12 shown in fig. 5 is a sectional longitudinal view, seen from a side face, i.e. where the tightening means is thinnest. The third embodiment 12 corresponds substantially to the embodiment 8 shown in fig. 3, but is further provided with a plurality of spaced apart first protrusions 13' on the widest face of the tie part 2 and an enlarged eye part 4. Inside the eye 5 of the eye part 4 similarly configured second protrusions 13'', alternatively different protrusions, are provided for locking with the first protrusions 13'. A first protrusion 13' fits lockingly between second protrusion 13''. The first protrusions 13' may be provided along the entire length or only along a part of the length of the tie part 2. The first protrusions 13' may also serve for engaging bones, in particular vertebrae's and surrounding tissue, and as a result of which also functions as a temporary or permanent biological flexible and yieldable anchor means. Arrows B indicate loop formation.

Fig. 6 shows a sectional longitudinal view, seen from a side face, of a fourth embodiment of a tightening means 14 according to the present invention. The tightening means 14 corresponds substantially to the third embodiment 12 and for like part same reference numerals are used. The difference between said embodiments 12,14 consist in that the continuous thread 9' is substituted with shorter overlaying metal strips 15a, 15b, 15c, 15d, 15e, 15d, 15e, 15f, 15g overlapping in parallel along the length of the tie part. This embodiment 14 has a high level of tensioning strength due to embedded metal strips, and at the same time high level of stretchability due to the overlapping lengths of metal strips 15a, 15b, 15c, 15d, 15e, 15d, 15e, 15f, 15g. The protrusions alongside the wide face of the tie part 2 are in the fourth embodiment 14 configured as serrations 13a for locking with corresponding protrusions 13b, configured as serrations on a flexible tongue inside the eye 5 of the eye part 4.

Fig. 7 shows a sectional longitudinal view, seen from a side face, of yet another embodiment for a tightening means 16 according to the present invention. This fifth embodiment 16, corresponds substantially to the embodiment 12, but instead of a continuous metal thread 9, the tightening means 16 employs a longitudinal channel 17 filled with a radiopaque material 18 such as barium sulphate, for making the tightening means 16 easy identifiable using X-ray imaging techniques. This embodiment 16 is particular flexible and bendable.

Fig. 8 shows a perspective view of the embodiment 12 shown in fig. 5 formed as a closed loop, as indicated with arrow B, where the free end 3 has been threaded through the eye 5 of the eye part 4 to engage the eye part 4 in a locking manner. The person skilled in the art understands that the formation of the loop is made in the same manner as a conventional cable tie. Whether or not the tightening means is adapted for engaging by means of protrusions or by means of frictional engagement or both depend of the surgeon's choice and the surgical conditions .

Fig. 9a illustrates schematically the curvature of a normal straight spine 22' of a person P. For illustrative reasons only a limited number of the vertebras 25 of the spine 22' are indicated. A normal spine 22' has normal curvatures, which goes both forward and backward as indicated in the side view of fig. 9b.

Scoliosis, which is the most common type of abnormal spine curvature, is indicated in fig. 9c, which shows the spine 22 from the back of person P. The laterally curved spine 22 is symptomatic of scoliosis.

Another common type of abnormal spine curvature is indicated in fig. 9d in which the spine 22'' is seen from the side of the patient P. The backward curvature forms a hump on the spine 22', which hump is symptomatic of hyperkyphosis .

Fig. 10 illustrates the conventional Luque instrumentation for correcting scoliosis, wherein parallel rods 19,20 are arranged alongside the thoracic region 21 of a scoliosis spine 22 to distract and correct the abnormal curved spine 22. One rod 19 is secured to the thoracic region closest to the lumbar region 23 and the other rod 20 to the thoracic region closest to the cervical region. Subsequently the rods 19,20 are forcedly approached to each other and secured to each other and to one or more vertebrae's 25 using one or more metal wires 24, of which four set of four wires each are shown in fig. 10. The wires 24 hold the distracted and corrected spine 22 in a desired straightened position. The spinal structure and the Luque instrumentation are known to the skilled surgeon and will not be discussed in detail. Essential to the Luque technique is however that the steel wires 24 must be secured to the rods 19,20 and to one or more adjacent vertebrae's 25 by continuously twisting at least one sublaminar arranged steel wire around both vertebrae 25 and rod 19,20 to a tightness decided sufficient and appropriate by the surgeon who in fact has no clear idea of how strong a tightening force that is applied or needs to be applied. After twisting excess wire is cut off and disposed, and the twisted bit is bend alongside the rod, as indicated along rod 19. When the rods 19,20 are to be removed the metal wires are cut or untwisted at the risk of substantial cutting and injuring the patient during release of tensioning force. The pointed tips of the cut ends sticks out to all sides and may injure the patient during withdrawal.

Fig. 11 shows schematically six tightening means 12 inserted at a part of the lumbar region of the spine 22 for securing rods 19,20 respectively to vertebrae's 25. The free end 3 of the tie part 2 is passed around the rods 19,20 and vertebrae's 25 in the same manner as the Luque wires. The free end 3 is passed through the eye 5 of the eye part 4 to engage the eye part 4, and the loop is tightened and tensioned using an appropriate tensioning tool. The free end 3 may or may not be cut off, as indicated in fig. 11, preferably once the selected tension level has been confirmed. The surgeon may choose to leave a free end 3 for later further tightening or tensioning.

The tightening means 1 ', 8, 11, 12, 14, 16 according to the present invention provides an alternative to the conventional metal wire securing. The inventive tightening means is both flexible and a known degree of tensioning level and force can be applied using appropriate tools when pulling the free end through the eye part for reducing the loop size. Due to the plastic material the tightening means has smooth edges allowing insertion and removal with a minimum of injury to the patient. The radiopaque metal strip, band or thread provides for reinforcement of the tightening means and allows the full circumference of the loop to be identified, which among other things makes confirmation of correct placement and tension and tightening level extremely easy and handy.

Bleeding, postoperative pain, pseudoarthrosis, disk degeneration and low back pain are just some of the known adverse effects, which are often seen in conventional spine surgery. The present invention is believed to reduce occurrence of some of the known adverse effects.

Although the invention is described for use in spinal instrumentation, such as correcting the thoracic region, the tightening means can of course be used anywhere in the body where securing of structures to each other is necessary, including the lumbar region and the cervical region but also fro example the extremities and the sternum.

Furthermore combinations of features of the embodiments shown and described in the figures are also comprised within the scope of the present invention, as well as the protrusions along the tie part and inside the eye part may have any configuration that provide for secure locking of the loop at a predetermined position. Due to the very high level of bendability, flexibility and tensioning and tightening force, the superiority of the inventive tightening means is evident. The tightening means according to the present invention is much easier to manipulate than known wire means and constitute a very reliable surgical fastening means, in particular an orthopaedic fastening means.

Claims

1. A tightening means (1 '; 8; 11; 12; 14; 16) for orthopaedic surgery comprising a tie part (2) having a free end (3) and an opposing eye part (4) with an eye (5) for threading the free end (3) of the tie part (2) to form a closed loop around one or more objects, characterised in that the tie part (2) is provided with at least one continuous radiopaque band, strip or thread ( 9 ; 9 ' , 9 'a, 9 'b; 15a, 15b, 15c, 15d, 15e, 15f, 15g;17) .

2. A tightening means (1 '; 8; 11; 12; 14; 16) according to claim 1, characterised in that the at least one single band, strip or thread (9; 15; 17) is provided along the entire length of the tie part (2) ,

- as one single band, strip or thread (9) having the same length as the tie part and arranged along the entire length of said tie part, or

- as several parallel bands, strips or threads (9a, 9b) having the same length as the tie part and arranged along the entire length of the tie part, or

- as bands, strips or threads ( 9 ; 9 ' , 9 'a, 9 'b; 15a, 15b, 15c, 15d, 15e, 15f, 15g; 17) having lengths shorter than the tie part (2) and arranged in overlapping relationship along the entire length of the tie part (2) .

3. A tightening means (1 '; 8; 11; 12; 14; 16) according to claims 1 or 2, characterised in that the at least one continuous radiopaque band, strip or thread ( 9 ; 9 ' , 9 'a, 9 'b; 15a, 15b, 15c, 15d, 15e, 15f, 15g; 17) is embedded in an outer covering, preferably a biological acceptable plastic material.

4. A tightening means ( 1 ' ; 8 ; 11 ; 12 ; 14) according to any of the claims 1, 2 or 3, characterised in that the at least one continuous radiopaque band, strip or thread (9;9^f, 9'a, 9'b;15a, 15b, 15c, 15d, 15e, 15f, 15g) is made of a metal or a metal alloy.

5. A tightening means (16) according to any of the claims 1 or 2, characterised in that the at least one continuous radiopaque band, strip or thread is hollow and include an X- ray identifiable substance (17), such as barium sulphate.

6. A tightening means (1 '; 8; 11; 12; 14; 16) according to any of the preceding claims 1 - 5, characterised in that at least one face of the tie part (2) has a plurality of protrusions (13; 13'; 13a) for engaging with the eye part (5) or a part of the eye part, preferably engaging corresponding protrusions (13; 13 ' ' , 13b) protruding inside the eye of the eye part.

7. A tightening means (1 '; 8; 11; 12; 14; 16) according to claim 6, characterised in that any of the protrusions is configured as serrations (13b) or barbs (13', 13''), preferably serrations or barbs protruding in an angle toward the eye part smaller than 90°, preferably smaller than 60°, and most preferred smaller than 45°.

8. A method of performing spinal (22) curve correction including the steps of - performing any of an anterior spinal approach, a posterior spinal approach or a combination of these spinal approaches to expose one or more vertebrae (25),

- removing outgrowths along one or more vertebrae's (20),

- placing bone grafts across the exposed surface of the one or more vertebrae's (25), inserting at least one correction rod (19,20) along the patients spine (22), characterised in that the method comprises the step of securing the at least one correction rod (19,20) to one or more vertebrae's (25) using one or more tightening means ( 1 ' ; 8 ; 12 ; 14; 16 ) according to any of the preceding claims 1 - 7, and - tightening the tightening means (1 '; 8; 11; 12; 14; 16) to an appropriate degree.

9. A method according to claim 8, characterised in that the method comprises the further step of further tightening the tightening means (1 '; 8; 11; 12; 14; 16) during recovery of the patient .

10. A method according to any of the preceding claims 8 or 9, characterised in that the surgical spinal (22) curve correction is for correcting scoliosis using a tightening means ( 1 ' ; 8 ; 11 ; 12 ; 14 ; 16 ) .