System for minimizing overloads after spinal fixation

Abstract

Disclosed herein is a system (1) for establishing interplaying load paths in a fusion procedure of a spinal segment (2) between an upper vertebra (3) and a lower vertebra (4) for minimizing post-fixation overloads. The system (1) comprises a first stiffener (5) for forming a primary load path (6) between the upper vertebra (3) and the lower vertebra (4), the first stiffener (5). The system further comprises a tension band (7) for forming a secondary load path (8) across the upper vertebra (3) and the lower vertebra (4).

Description

[0001] P29158PC00 06.02.2026

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[0003] System For Minimizing Overloads After Spinal Fixation FIELD OF THE DISCLOSURE

[0004] This disclosure relates to medical devices in general and more particularly to spinal fixation.

[0005] BACKGROUND OF THE DISCLOSURE

[0006] Spinal fixation techniques such as spinal fusion have become a common surgical procedure, among others in the treatment of degenerative disorders of the spine. The indications for this surgical procedure are diverse and include low-back pain due to facet joint osteoarthritis, degenerative spondylolistheses, degenerative scoliosis and segmental instability. The latter can also be a result of iatrogenic destabilization following surgical resection of ligamentous structures as well as the facet joint.

[0007] However, spinal fusion and other spinal fixation techniques can be associated with serious long-term complications such as adjacent segment degeneration (ASD), proximal junctional kyphosis (PJK), screw loosening, pseudarthrosis, implant failure, and, in rare cases, neurovascular injury during implant insertion. An inappropriate redistribution of loads with subsequently increased biomechanical stress are believed to act as accelerators of ASD and proximal junctional kyphosis. Further, long fusions can lead to a relevant, irreversible loss of motion, which can cause postural changes. Proximal junctional kyphosis (PJK) may be defined as a 10 degrees or more increase in kyphosis, relative to the preoperative measurements, between the inferior endplate of the uppermost instrumented vertebra and the superior endplate of the vertebra two levels above the uppermost instrument vertebra.P29158PC00 06.02.2026

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[0009] More generally, the load redistributions caused by spinal fusion and other spinal fixation techniques may cause local overloads in certain parts or sections of the spine. These overloads may cause severe patient outcomes, including the ones above.

[0010] Thus, there is a need to provide improved spinal fixation implants. More broadly, there is a need to improve load distribution after spinal fixation in order to minimize or prevent ASK, PJK and other complications.

[0011] SUMMARY OF THE DISCLOSURE

[0012] It is a general object of the present disclosure to provide a system for establishing interplaying load paths in a fusion procedure of a spinal segment between an upper vertebra and a lower vertebra for minimizing post-fixation overloads. In particular, it is an object of at least some embodiments of the disclosure to enhance load distribution in a spinal segment after spinal fixation, e.g. spinal fusion. Preferably, a system would be provided which established a balancing load path aimed to distribute the loads more evenly across the spinal segment. For example, in at least some embodiments, it is an object to minimize local overloads in the region of an uppermost instrumented vertebra and / or in the region of a lowermost instrumented vertebra.

[0013] The general object is achieved by the subject-matter of the independent claims. Further favorable embodiments follow from the dependent claims and the overall disclosure.

[0014] In a first aspect, the present disclosure provides a system for establishing interplaying load paths in a fusion procedure of a spinal segment between an upper vertebra and a lower vertebra. The system is suitable for minimizing post-fixation overloads, such as post-fusional overloads.P29158PC00 06.02.2026

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[0016] The system comprises a first stiffener for forming a primary load path between the upper vertebra and the lower vertebra. The first stiffener is typically attached to and interconnects in the mounted position the upper vertebra and the lower vertebra.

[0017] The system further comprises at least one tension band for forming a secondary load path across the upper vertebra and the lower vertebra.

[0018] By forming a primary load path and a secondary load path, the loads can be distributed more evenly after the spinal fixation. In particular, the secondary load path may be used to selectively strengthen a posterior load path of the spinal segment, thereby achieving a balance between tensile and compressive loads and, in particular, alleviating overloads that would otherwise act on the vertebral bodies due to a weakened posterior load path in the absence of the secondary load path described herein.

[0019] This applies in particular to load distribution across the upper vertebra and the lower vertebra. For such loads, the secondary load path formed by the tension band offers an additional opportunity for load distribution. By transferring the loads more efficiently across the upper vertebra and the lower vertebra, local overloads are prevented, which ultimately prevents adjacent segment degeneration and other related complications.

[0020] Furthermore, by providing an in a mounted position interplaying primary load path and secondary load path, the system can be easily tailored to the biomechanical circumstances of a given patient. For example, it may be beneficial to adjust a distance between the primary and secondary load path specific to a given patient, or to adjust the tension of the tension band depending on a remaining load balancing capability of the spinal segment post-fusion. Such patient-specific adaptations can be easily made with the system described herein because two variables, namely the stiffener and the tension band, can be adjusted independently of each other.P29158PC00 06.02.2026

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[0022] The system described herein is particularly advantageous when considering that many spinal fixation operations such as spinal fusion negatively affect the posterior midline structures (including e.g. the interspinous ligament and / or the supraspinous ligament) and diminish their load-bearing capabilities, as illustrated further below in the context of Fig. 1. For example, spinal fixation operations such as spinal fusion frequently result in removal of at least parts of the interspinous ligament and / or the supraspinous ligament. In many instances, even the spinous processes of instrumented vertebrae are removed in order to properly approach and manipulate the pedicles and other parts of the vertebrae. The impairment of the posterior midline structures leads to increasing midline decompression over time, which in the case of instrumented vertebrae leads to an increasing imbalance between the tensile loads acting on the impaired posterior midline and the compression forces acting on the vertebral bodies. Ultimately, this will result in load imbalances, including excessive compressive loads on the spinal bodies, which contribute to adjacent segment degeneration.

[0023] These problems can be alleviated by providing the secondary load path, which can at least partially compensate the impairment of the posterior midline structures. More specifically, a more even balance between tensile loads acting on the posterior midline and compressive forces acting on the spinal bodies is achieved.

[0024] To facilitate understanding of the present disclosure, the disclosure is described in the context of anatomical directions. It is understood that these directions refer to the mounted position of the system. However, it is understood that the system may also exist in an unmounted position. Dorsal direction, as used herein, refers to a direction from or to a back, e.g. from or to a back of a patient. It may also be labelled as posterior direction. Lateral direction, as used herein, refers to a direction orthogonal to the dorsal direction. The lateral direction typically extends from a first lateral side (e.g. a left side) of a patient to an opposite lateral side of the patient (e.g. a right side). Cranial direction, as usedP29158PC00 06.02.2026

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[0026] herein, refers to a direction towards a head, e.g. towards a head of the patient. Typically, the dorsal direction, the lateral direction and the cranial direction are each orthogonal to each other. Reference may also be made to a caudal direction, which is opposite to and parallel to the cranial direction. In other words, it is understood that the cranial and caudal direction are parallel to each other but point in opposite directions.

[0027] Furthermore, the disclosure is described in the context of an upper vertebra and a lower vertebra. The upper vertebra and the lower vertebra typically define the spinal segment which is to be instrument, i.e. to which a stiffener is to be applied. In other words, the portion of the spinal segment which is to be instrumented extends from the lower vertebra to the upper vertebra. The upper vertebra is typically arranged further in cranial direction than the lower vertebra. Conversely, the lower vertebra is typically arranged further in caudal direction than the upper vertebra. Thus, the upper vertebra may optionally also be labelled as cranial vertebra and the lower vertebra may optionally be labelled as caudal vertebra. Similarly, the directional specification upper with respect to the mounted position may optionally be labelled as cranial. For example, a vertebra above the upper vertebra may optionally be labelled as a vertebra arranged further in cranial direction than the cranial vertebra. Preferably, the vertebra above the upper vertebra is a neighboring vertebra. Similarly, the directional specification lower with respect to the mounted position may optionally be labelled as caudal. For example, a vertebra below the lower vertebra may optionally be labelled as a vertebra arranged further in caudal direction than the caudal vertebra. Preferably, the vertebra below the lower vertebra is a neighboring vertebra.

[0028] Depending on the application, the system may comprise one or more different kinds of tension bands. To distinguish between different possible embodiments of the tension band, reference will be made hereinafter to a first tension band, a second tension band,P29158PC00 06.02.2026

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[0030] a third tension band, a fourth tension band and a fifth tension band. The numerical references (first, second, third, fourth, fifth) are intended to facilitate understanding of the disclosure by clearly distinguishing between some of the different embodiments of the tension band. However, the numerical references are not to be understood as implying a dependence or hierarchical order between the different embodiments of the tension band. As an example, if the system comprises the second tension band, this does not imply that the system must also comprise the first tension band. Rather, in embodiments in which the system comprises the second tension band, the system may or may not also comprise the first tension band. In other words, more broadly, the first tension band, the second tension band, the third tension band, the fourth tension band and the fifth tension band may be provided independently of each other. In still other words, the at least one tension band may comprise: the first tension band and / or the second tension band and / or the third tension band and / or the fourth tension band and / or the fifth tension band.

[0031] Whenever reference is made hereinafter to “the least one tension band”, the respective reference may optionally apply to all of the possible embodiments of the tension band, unless indicated otherwise or unless the context clearly dictates otherwise.

[0032] In some embodiments, the at least one tension band comprises a first tension band interconnecting in the mounted position:

[0033] - a spinous process of the upper vertebra and / or a spinous process of a vertebra above the upper vertebra; and

[0034] - a spinous process of the lower vertebra and / or a spinous process of a vertebra below the lower vertebra.P29158PC00 06.02.2026

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[0036] It is understood that the previous sentence is to be understood such that the first tension band interconnects at least one of the spinous processes mentioned under the first bullet point and at least one of the spinous processes mentioned under the second bullet point.

[0037] Depending on the application, the at least one tension band may have different arrangements with respect to the first stiffener. In some embodiments, the at least one tension band is not directly connected to the first stiffener (and is preferably also not connected to the second stiffener or any further stiffeners, in embodiments where a second stiffener or any further stiffeners are provided). In other words, for example, the at least one tension band does not contact the first stiffener in some embodiments (and preferably also does not contact to the second stiffener or any further stiffeners, in embodiments where a second stiffener or any further stiffeners are provided). In those variants in which the first stiffeners comprises a first connecting rod, the at least one tension band may e.g. not be directly connected to the first connecting rod (and preferably also not connected to the second connecting rod or any further connecting rods).

[0038] These embodiments are particularly advantageous because they allow the secondary load path to be independent from the primary load path. This ensures a more even balance of the overall loads in the vertebral segment. Furthermore, by having an independent secondary load path, the secondary load path can be adjusted more precisely and with greater dimensions of freedom to accommodate the patient-specific biomechanical needs. For example, in other embodiments in which the at least one tension band is directly connected to the first stiffener, the tensile load transferred through the at least one tension band may at least partially be transferred to the stiffener forming the primary load path, which may, at least in some embodiments, be undesirable because it would reduce the strengthening effect on the posterior midline. By contrast, if the at least one tension band is not directly connected to the first stiffener (e.g. the connecting rod), itP29158PC00 06.02.2026

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[0040] may also be arranged in the region of the posterior midline and may strengthen the posterior load path more strongly, e.g. because it may exert a stronger leverage by being arranged further from the first stiffener.

[0041] In some embodiments, the at least one tension band is in the mounted position offset from the first stiffener (e.g. from the first connecting rod of the first stiffener, where the first stiffener comprises a first connecting rod) in a dorsal direction and / or in a lateral direction. For example, the at least one tension band may in the mounted position be offset from the first stiffener (e.g. from the first connecting rod, where the first stiffener comprises the first connecting rod) in the dorsal direction. Alternatively or in combination, the at least one tension band may in the mounted position be offset from the first stiffener (e.g. from the first connecting rod, where the first stiffener comprises a first connecting rod) in the lateral direction.

[0042] It is particularly preferable for the at least one tension band to be offset from the first stiffener (e.g. the first connecting rod) in the mounted position in the dorsal direction. These embodiments allow to exert a stronger leverage effect, which allows the at least one tension band to strengthen the posterior load path more effectively. Ultimately, this allows a more balanced load distribution across the spinal segment post-fusion. For similar reasons, it may also be advantageous for the at least one tension band to be offset from the first stiffener (e.g. the first connecting rod) in the lateral direction, e.g. to mitigate or minimize the risk of scoliosis or other sideway curvatures of the spine.

[0043] Depending on the application, different offsets may be chosen. In some embodiments, the at least one tension band is offset in the mounted position from the first stiffener (e.g. the first connecting rod) in the dorsal direction by at least 1 mm, preferably by at least 5 mm, more preferably by at least 10 mm.P29158PC00 06.02.2026

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[0045] In some embodiments, the first stiffener comprises a first pedicle screw, a second pedicle screw and a first connecting rod, as described in further detail below. In these embodiments, depending on the application, the at least one tension band may have different arrangements relative to the first connecting rod (or the first stiffener more broadly) in the mounted position. In typical embodiments, the at least one tension band is arranged in the mounted position essentially parallel to the first connecting rod. In embodiments in which the system comprises a second connecting rod and possibly even further connecting rods, the at least one tension band may e.g. be arranged in the mounted position essentially parallel to the first connecting rod and to the second connecting rod and optionally also to the further connecting rods. These embodiments are advantageous because they allow a more balanced load distribution across the spinal segment. As an example, a parallel arrangement is particularly beneficial to efficiently strengthen the load distribution across the posterior midline because many of the loads acting on the posterior midline, especially tensile loads, act in a direction parallel to the connecting rod in the mounted position (or at least have a significant vector component in a direction parallel to the connecting rod). Thus, the parallel arrangement allows to optimally align the at least one tension band with the posterior midline and its associated load path. By contrast, if the at least one tension band is not arranged essentially parallel to the connecting rod, this could result relative to the natural load path of the posterior midline and could result in local overloads. It is understood that due to the natural curvature of the spine, the tension load band may deviate slightly from a perfectly parallel arrangement with respect to the rod. Another possible reason for a slight deviation could be a possible slight curvature of the rod. In some embodiments, the at least one tension band and the first connecting rod may e.g. define an angle in the mounted position of less than 15°, preferably less than 10°, e.g. less than 5°, such as essentially 0°.

[0046] In some embodiments, the first tension band is configured to extend in the mounted position at least from the spinous process of the upper vertebra of the spinal segment toP29158PC00 06.02.2026

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[0048] the spinous process of the lower vertebra of the spinal segment. These embodiments are advantageous in order to establish a secondary load path that extends across the entire spinal segment. Optionally, the tension band may even extend beyond (in cranial direction) the upper vertebra and / or beyond (in caudal direction) the lower vertebra.

[0049] Depending on the application, it can be advantageous for the at least one tension band to extend beyond an upper and / or lower end of the first stiffener (e.g. the first connecting rod) in order to achieve an efficient overall load balance post-fusion and to further reduce the risk of local overloads. In particular, the risk of local overloads post-fusion is minimized in a transition region between the outermost (i.e. upper or lower) instrumented vertebrae and their neighboring non-instrumented vertebrae. These transition regions are particularly prone to overloads and, consequently, many degenerative complications such as adjacent segment degeneration, kyphosis, etc. tend to occur in these transition regions. By extending the at least one tension band beyond an upper end (respectively lower end) of the connecting rod, these transitions regions are strengthened more effectively, which ultimately reduces the risk of degenerative complications. Thus, in some embodiments, the at least one tension band extends in the mounted position beyond an upper end of the first stiffener (e.g. the first connecting rod of the first stiffener, where the first stiffener comprises a first connecting rod) in a cross-section orthogonal to the dorsal direction. In other words, the at least one tension band may extend in the mounted position beyond (i.e. further in cranial direction than) an upper (i.e. cranial) end of the first stiffener (e.g. the first connecting rod) in said cross-section. Alternatively or in combination, the at least one tension band may extend in the mounted position beyond a lower end of the first stiffener (e.g. the first connecting rod of the first stiffener) in a crosssection orthogonal to the dorsal direction. In other words, the at least one tension band may extend in the mounted position beyond (i.e. further in caudal direction than) a lower (i.e. caudal) end of the first stiffener (e.g. the first connecting rod of the first stiffener) in a cross-section orthogonal to the dorsal direction. Where the system also comprises aP29158PC00 06.02.2026

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[0051] second connecting rod and optionally even further connecting rods, these embodiments may optionally also apply to the second connecting rod and optionally also to the further connecting rods. For example, in some embodiments, the at least one tension band extends in the mounted position beyond an upper end of the first stiffener (e.g. the first connecting rod) and beyond an upper end of the second stiffener (e.g. the second connecting rod) in a cross-section orthogonal to the dorsal direction. Optionally, the at least one tension band may further extend in the mounted position beyond a lower end of the first stiffener (e.g. the first connecting rod) and beyond a lower end of the second stiffener (e.g. the second connecting rod) in a cross-section orthogonal to the dorsal direction.

[0052] Depending on the application, the secondary load path formed by the at least one tension band may have different trajectories and may be realized in different fashions. For example, the secondary load path may extend from the upper vertebra to the lower vertebra of the spinal segment either directly or indirectly, e.g. through the intermediacy of intermediate load-bearing structures. As an example of an indirectly extending secondary load path, an upper tension band could e.g. interconnect the spinous process of the upper vertebra of the spinal segment with the first stiffener (e.g. the first connecting rod of the first stiffener, where the first stiffener comprises a first connecting rod), and a lower tension band (not contacting the upper tension band) could e.g. interconnect the first stiffener (e.g. the first connecting rod of the first stiffener) with the spinous process of the lower vertebra of the spinal segment. In this case, the secondary load path would extend through the intermediacy of the first stiffener (e.g. the first connecting rod). More specifically, the secondary load path would extend first through the upper tension band, then through a portion of the first stiffener (which portion corresponds to the distance between the attachment points at which the first stiffener is connected to the upper respectively the lower tension band), and finally through the lower tension band. Such an indirect arrangement could be useful to make use of the typically high tensile strength of the first stiffener (e.g. of the first connecting rod). Thus, in some embodiments, the tension bandP29158PC00 06.02.2026

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[0054] indirectly transfers tension loads between the upper vertebra of the spinal segment and the lower vertebra of the spinal segment in the mounted position.

[0055] However, it was found to be particularly advantageous for at least one of the at least one tension band to transfer the tension loads directly. Thus, in some embodiments, the first tension band directly transfers tension loads between the upper vertebra of the spinal segment and the lower vertebra of the spinal segment in the mounted position. One advantage of such a direct transfer of the tension loads is that they allow a more immediate load transfer between the upper and lower vertebrae of the spinal segment. A direct transfer of the tension loads is also compatible with a parallel arrangement in the mounted position between the tension band and the first connecting rod, which is associated with numerous advantages as outlined above. A further advantage of a direct transfer of the tension loads is that the direct transfer increases the independence of the secondary load path with respect to the primary load path, which is advantageous for the reasons outlined in further detail above. A further advantage is that a direct transfer of the tension loads most closely mimics the natural load environment of the spinal segment pre-fusion. Finally, a direct transfer of the tension loads facilitates fine-tuning the biomechanical properties of the secondary load path and balancing the overall load distribution because it avoids making more complicated considerations based on the influence of intermediate structures on the secondary load path.

[0056] Depending on the application, the at least one tension band may have different shapes and contours. For example, the at least one tension band may essentially form a longitudinally extending strap. As an example, one end of the strap could be configured to be interconnected with the upper vertebra and an opposite end could be configured to be interconnected with the lower vertebra. It was found to be particularly advantageous to make use of a tension band that forms a closed loop in the mounted position. Such aP29158PC00 06.02.2026

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[0058] loop could e.g. be wrapped around the spinous processes of the upper and lower vertebrae, thereby interconnecting them and establishing the secondary load path. One advantage of such a loop is that the tension band may be interconnected to the upper and lower vertebrae by abutting on a surface of the upper and lower vertebrae. This allows a smooth introduction of the tensile loads and an even distribution of the tensile loads.

[0059] Thus, in some embodiments, at least one of the at least one tension band extends in a longitudinal direction of the respective tension band from a first end to a second end configured to be interconnected in the mounted position to the first end for forming a closed loop. Preferably, the closed loop formed by the respective tension band is in its circumference adjustable. For example, by adjusting the circumference, a tension load exerted by the respective tension band may be adjusted, which ultimately allows controlling and adjusting the secondary load path.

[0060] Depending on the application, the loop formed by the at least one tension band may be implanted in different arrangements and orientations. In some embodiments, as briefly outlined above, the closed loop may be used to interconnect the upper vertebra and the lower vertebra. To do this, use could be made of different sections of the upper and lower vertebra, e.g. their spinous processes, transverse processes, laminae or other parts. However, it is preferable to make use of the spinous processes because they are optimally positioned to strengthen the posterior midline. Furthermore, making use of the spinous processes allows to arrange the tension band essentially parallel to the connecting rod and / or offset from the connecting rod in dorsal direction, both of which are advantageous arrangements as outlined in detail above. Thus, in some embodiments, the first tension band forms the closed loop configured to encircle in the mounted position:

[0061] - the spinous process of the upper vertebra or the spinous process of a vertebra above the upper vertebra; andP29158PC00 06.02.2026

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[0063] - the spinous process of the lower vertebra or the spinous process of a vertebra below the lower vertebra.

[0064] It is understood that the previous sentence is to be understood such that the encircling refers to the first bullet point and to the second bullet point. In other words, it is to be understood such that the spinous process of either the upper vertebra or of the vertebra above the upper vertebra and the spinous process of either the lower vertebra or of the vertebra below the lower vertebra is encircled.

[0065] Alternatively or in combination, similar embodiments can also be envisioned for the second tension band and / or the third tension band. Thus, in some embodiments, the second tension band forms a / the closed loop configured to encircle in the mounted position:

[0066] - the spinous process of the upper vertebra and

[0067] - the spinous process of a vertebra above the upper vertebra.

[0068] Alternatively or in combination, in some embodiments, the third tension band forms a / the closed loop configured to encircle in the mounted position:

[0069] - the spinous process of the lower vertebra and

[0070] - the spinous process of a vertebra below the lower vertebra.

[0071] Irrespective of whether the closed loop is formed by the first tension band, by the second tension band or by the third tension band, depending on the application, the closed loop formed by the tension band may be established in different ways. For example, in some embodiments, the first end of the at least one tension band and the second end of the at least one tension band may be directly connected to each other, e.g. such that theyP29158PC00 06.02.2026

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[0073] contact each other in the mounted position. As an example, the first end and the second end of the at least one tension band may be overlapped and then sutured together or stitched together or otherwise connected to each other. These embodiments may be advantageous to provide a long-lasting connection and to minimize the exposure of the surrounding tissue to foreign tissue or foreign materials.

[0074] However, it may also be advantageous to interconnect the first end and the second end of the at least one tension band in other ways, e.g. using an intermediate structure. In some embodiments, for example, the system further comprises a first lock interconnecting in the mounted position the first end and the second end of the at least one tension band. Once again, it is understood that the first lock is configured for interconnecting in the mounted position the first end and the second end of the at least one tension band. One advantage of using such a first lock is that implantation and in particular tensioning of the at least one tension band are facilitated. A first lock may also allow more control over the pre-tension that is being applied to the at least one tension band.

[0075] Depending on the application, different first locks may be used. In some embodiments, the first lock comprises a button, such as a self-locking button. For example, the button may be interconnected with the first end of the at least one tension band and / or with the second end of the respective tension band such that a free end of the first end of the at least one tension band and / or a free end of the second end of the respective tension band may be pulled to apply a tension to the at least one tension band, but where the first end (of the at least one tension band) and / or the second end (of the respective tension band) blocks itself when the pull-force is removed, thereby preventing loss of the applied tension.

[0076] In some embodiments, in an unlocked state of the first lock the first end and the second end of the respective tension band are displaceable towards each other, wherein in aP29158PC00 06.02.2026

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[0078] locked state of the first lock displacement of the first end and the second end of the respective tension band away from each other is blocked.

[0079] In some embodiments, an operation length of the first end of the at least one tension band is adjustable by pulling a free end of the first end, thereby displacing the first end (of the at least one tension band) with respect to the first lock. Alternatively or in combination, in some embodiments, an operation length of the second end (of the at least one tension band) is adjustable by pulling a free end of the second end, thereby displacing the second end (of the respective tension band) with respect to the first lock.

[0080] In some embodiments, the first lock comprises a ratchet element. For example, the first lock may comprise a ratchet element configured to block in the locked state displacement of the first lock along the length of the first end (of the at least one tension band) and / or along the length of the second end (of the respective tension band) in the at least one direction.

[0081] In some embodiments, in the mounted position, the at least one tension band is pretensioned with respect to a neutral position of the spinal segment. Thereby, an elastic resistance to flexion beyond the neutral position can be provided. In other words, the at least one tension band may be configured to maintain in the mounted position a pretension with respect to a neutral position of the spinal segment. Such a pre-tension is advantageous in order to most closely mimic the natural biomechanical environment of a healthy spinal segment pre-tension. More specifically, in a healthy spinal segment, the ligaments constituting the posterior midline (e.g. the interspinous ligaments and supraspinous ligaments) are typically also in a pre-tensioned state with respect to the neutral position of the spinal segment.P29158PC00 06.02.2026

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[0083] The first stiffener is configured for forming the primary load path between the upper vertebra and the lower vertebra. Thus, the primary load path typically extends from the upper vertebra to the lower vertebra.

[0084] In a typical embodiment, the first stiffener is made of a stiff material. In some embodiments, the first stiffener is essentially incompressible and / or essentially inextensible. As an example, the first stiffener may e.g. be made of a metal, such as titanium, stainless steel, cobalt chrome, or similar materials typically used for spinal rods. Irrespective of the material or the compressive properties, the first stiffener may optionally be essentially straight or rounded.

[0085] The embodiments described in the previous paragraph may optionally also apply to the second stiffener and / or to any further stiffeners, in case a second stiffener and / or further stiffeners are provided.

[0086] Depending on the application, different first stiffeners (and optionally also second stiffeners) may be used. For example, the first stiffener and optionally the second stiffener may be selected in accordance with a desired degree of fixation or range of motion postfusion. As an example, rather rigid first stiffeners may be selected to achieve high immobilization, while less rigid and more flexible stiffeners may be more advantageous to maintain a greater range of motion post-fusion.

[0087] In some embodiments, the first stiffener comprises a first pedicle screw or the like in a mounted position attached to the upper vertebra and a second pedicle screw in the mounted position attached to the lower vertebra. The first stiffener may further comprise a first connecting rod in the mounted position attached to and interconnecting the first pedicle screw and the second pedicle screw to each other. In these embodiments, theP29158PC00 06.02.2026

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[0089] at least one tension band is preferably arranged in the mounted position essentially parallel to the first connecting rod.

[0090] In some embodiments, the system further comprises a second stiffener or optionally even further stiffeners. The second stiffener is configured stiffener for forming together with the first stiffener the primary load path between the upper vertebra and the lower vertebra. The second stiffener comprises:

[0091] - a third pedicle screw in a mounted position attached to the upper vertebra and a fourth pedicle screw in the mounted position attached to the lower vertebra; and

[0092] - a second connecting rod in the mounted position attached to and interconnecting the first pedicle screw and the second pedicle screw to each other.

[0093] One advantage of using a second stiffener is that the overall stability of the spinal segment is improved. Furthermore, a more balanced load distribution may be achieved because two different parts (e.g. two lateral sides) of the spinal segment may be instrumented.

[0094] In some embodiments, the first stiffener and the second stiffener are in the mounted position arranged parallel to each other. These embodiments can be useful in order to achieve a balanced load distribution and avoid any local overload that could result from angled arrangements.

[0095] Furthermore, irrespective of whether the stiffeners extend in parallel to each other or not, it is preferable for the first and second stiffener to be arranged on opposite lateral sides, i.e. on opposite sides with respect to a midline defined by the spinous processes of the vertebrae of the spinal segment. Thus, in some embodiments, the first stiffener and the second stiffener may in the mounted position arranged on opposite lateral sides of theP29158PC00 06.02.2026

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[0097] upper and lower vertebrae. These embodiments are advantageous because they contribute to a balanced load distribution post-fusion. In particular, a bending of the spinal segment or even the entire spine to one lateral side as a result of local overloads can be avoided more easily.

[0098] Depending on the application, the at least one tension band may have different arrangements with respect to the first stiffener and to the second stiffener in the mounted position. It is particularly preferable for the at least one tension band to be arranged in the mounted position between the first stiffener and the second stiffener in a cross-section orthogonal to the dorsal direction. It is understood that because the previous sentence explicitly refers to the cross-section orthogonal to the dorsal direction, it still allows for the at least one tension band to optionally be offset in dorsal direction from the first stiffener and / or the second stiffener.

[0099] Arranging the at least one tension band between the first and second stiffener is particularly advantageous because this arrangement closely mimics the natural biomechanical environment of the posterior midline of a healthy spinal segment. Furthermore, arranging the at least one tension band between the first and second stiffener provides a balanced load distribution and avoids the risk of any bends or overloads in lateral direction of the spinal segment which could result if, when viewed from the dorsal direction, the at least one tension band was e.g. arranged significantly closer to the first stiffener than to the second stiffener.

[0100] One advantage of using pedicle screws and one or more connecting rods for the first stiffener is that e.g. conventional pedicle screws may be used, which are well studied systems and widely used clinically. Furthermore, pedicle screws typically provide a high degree of structural hold and thereby high positional control.P29158PC00 06.02.2026

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[0102] However, for certain applications, it may be more advantageous to use less rigid systems. For example, in some embodiments, the first stiffener may involve facet fixation. One advantage of facet fixation is that they are highly compatible with minimally invasive placement, requiring only a small incision footprint. Furthermore, facet fixation techniques typically feature a low implant density and can often be implanted with few surgical maneuvers, thereby shortening surgery times and facilitating the surgeries. Lastly, facet fixation techniques tend to be less expensive because of the ability to use relatively simple implants such as compression screws, and the ability to use relatively simple instruments for implantation.

[0103] Thus, in some embodiments, the first stiffener comprises a first facet screw and a second facet screw.

[0104] For example, the first facet screw may pass in the mounted position through a first facet joint between the upper vertebra and the lower vertebra, thereby interconnecting in the mounted position the upper vertebra and the lower vertebra. Alternatively or in combination, the second facet screw may for example pass in the mounted position through a second facet joint between the upper vertebra and the lower vertebra, thereby interconnecting in the mounted position the upper vertebra and the lower vertebra.

[0105] It is understood that in the mounted position, the first facet screw is typically attached to and interconnects a first inferior articular process of the upper vertebra and a first superior articular process of the lower vertebra. It is also understood that the first inferior articular process of the upper vertebra and the first superior articular process of the lower vertebra together form the first facet joint. Thus, the first facet screw may e.g. comprise in longitudinal direction of the first facet screw arranged behind each other a first section for placement in the mounted position inside the first superior articular process of theP29158PC00 06.02.2026

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[0107] lower vertebra, and a second section for placement in the mounted position inside the first inferior articular process of the upper vertebra.

[0108] Depending on the application, different first and second facet screws can be used and the facet screws can have different arrangements. For example, in some embodiments, the first facet screw and the second facet screw are angled with respect to each other at less than 50° in the mounted position when viewed from the dorsal direction. For example, the first facet screw and the second facet screw are angled with respect to each other at less than 40°, e.g. less than 30°, such as less than 20°, in the mounted position when viewed from the dorsal direction. In some embodiments, the first facet screw and the second facet screw may extend in the mounted position essentially parallel to each other when viewed from the dorsal direction. For example, in some embodiments, the first facet screw and the second facet screw may each be an ipsilateral transfacet screw. Ipsilateral transfacet screws are typically used in the Boucher technique for facet fixation in which the ipsilateral transfacet screw enters into the inferior articular process just medial to the facet joint, crossing the facet joint into the ipsilateral articular surface. In other words, in the mounted position, ipsilateral transfacet screws typically extend posterior to anterior, and largely perpendicular to the facet joint. It is understood that in the embodiments described in this paragraph, slightly angled arrangements of the first and second facet screw are also tolerated. Thus, within the context of the embodiments of this paragraph, essentially parallel means that the first facet screw and the second facet screw are arranged at an angle with respect to each other of less than 50°, e.g. less than 40°, e.g. less than 30°, such as less than 20°.

[0109] In the embodiments described in the previous paragraph, the first facet screw and the second facet screw typically do not cross each other when viewed from the dorsal direction.P29158PC00 06.02.2026

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[0111] In some embodiments, the first facet screw and the second facet screw cross each other when viewed from the dorsal direction in the mounted position. For example, the first facet screw and the second facet screw may each be a contralateral translaminar transfacet screw. Contralateral translaminar transfacet screws are typically used in the Magerl technique for facet fixation in which the contralateral translaminar transfacet screw enters into the upper vertebra at the base of the contralateral spinous process and passes through the lamina before passing through the facet joint.

[0112] Irrespective of which type of facet screw for the first facet screw or any further facet screws, the at least one tension band is preferably not directly connected to the first stiffener or any optional further stiffeners, as outlined above. This allows the secondary load path to be independent from the primary load path. Alternatively or in combination, as outlined above, it is also preferable for the at least one tension band to be in the mounted position offset from the first stiffener in a dorsal direction and / or in a lateral direction.

[0113] Depending on the application, different tension bands may be used. For example, in some embodiments, the at least one tension band may be made of an elastic material, e.g. a hyperelastic material. Elasticity may e.g. provide for a smoother build-up of load upon increasing flexion and may also lead to a more balanced load distribution across the spinal segment. In cases where the at least one tension band abuts on or otherwise contacts one or more vertebrae for load transfer, an elastic at least one tension band may also enhance the load distribution, e.g. by increasing a contact surface across which the load is being distributed.

[0114] However, in some embodiments, it could be advantageous to choose an essentially inextensible and / or inelastic at least one tension band. Using an inextensible respectivelyP29158PC00 06.02.2026

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[0116] inelastic at least one tension band can be useful in order to minimize any compressive loads that could act on the spinal bodies, e.g. during flexion.

[0117] In some embodiments, the at least one tension band comprises or may even be made of a tendon, a ligament, an allograft, an autograft or a xenograft. Preferably, the at least one tension band element comprises an allograft. In some embodiments, the at least one tension band element comprises a synthetic material, such as a braid and / or weave and / or stitched material and / or felt. The synthetic material may e.g. be or comprise a tape. In some embodiments, the synthetic material is a non-metallic cerclage. Depending on the application, the non-metallic cerclage may be braided or woven from a polyblend of ultra-high molecular weight polyethylene and polyester materials. In some embodiments, the non-metallic cerclage is made from pure polyethylene terephthalate (PET). Additionally or alternatively, the non-metallic cerclage may be a flat braided suture or a woven suture. In some embodiments, the synthetic material is a metal.

[0118] Depending on the application, the at least one tension band may have different shapes and surface contours. In some embodiments, the at least one tension band is configured to abut or otherwise contact spinous processes arranged opposite of each other in the spinal segment.

[0119] In some embodiments, at least one of the at least one tension band (e.g. the first tension band and / or the second tension band) comprises a first load-bearing surface for contacting in the mounted position an upper edge (i.e. e.g. a cranial edge) of the spinous process of the upper vertebra of the spinal segment or an upper edge (i.e. e.g. a cranial edge) of the spinous process of the vertebra above the upper vertebra. In other words, the first load-bearing surface may be configured for contacting in the mounted position an upper edge (i.e. e.g. a cranial edge) of the spinous process of either the upper vertebra or of the vertebra above the upper vertebra.P29158PC00 06.02.2026

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[0121] Alternatively or in combination, at least one of the at least one tension band (e.g. the first tension band and / or the third tension band) may comprise a second load-bearing surface for contacting in the mounted position a lower edge (i.e. e.g. a caudal edge) of the spinous process of the lower vertebra of the spinal segment or a lower edge (i.e. e.g. caudal edge) of the spinous process of the vertebra below the lower vertebra. In other words, the second load-bearing surface may be configured for contacting in the mounted position a lower edge (i.e. e.g. a caudal edge) of the spinous process of either the lower vertebra of the spinal segment or of the vertebra below the lower vertebra.

[0122] As an example, in some embodiments, the first tension band comprises:

[0123] - a first load-bearing surface for contacting in the mounted position an upper edge of the spinous process of the upper vertebra of the spinal segment or an upper edge of the spinous process of the vertebra above the upper vertebra; and / or

[0124] - a second load-bearing surface for contacting in the mounted position a lower edge of the spinous process of the lower vertebra of the spinal segment or a lower edge of the spinous process of the vertebra below the lower vertebra.

[0125] In some embodiments, for example, the first tension band is configured for contacting in the mounted position the upper edge of the spinous process of the upper vertebra and the lower edge of the spinous process of the lower vertebra.

[0126] The embodiments described above are particularly advantageous because the contacting allows the at least one tension band to directly transfer the loads efficiently across the spinal segment. Furthermore, the spinous processes were found to be particularly advantageous to be contacted by the at least one tension band because they allow the at least one tension band to have a particularly advantageous relative arrangement withP29158PC00 06.02.2026

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[0128] respect to the first (and optionally the second) stiffener, namely offset in the dorsal direction (see associated advantages above) and optionally also between the first stiffener and the second stiffener (see associated advantages above).

[0129] It was found to be particularly advantageous for the at least one tension band to have a minimum width, at least in the region of the first load-bearing surface and / or in the region of the second load-bearing surface. Such a minimum width (e.g. of 2 or even 5 mm or more) is advantageous to distribute the load across a sufficiently large surface area and to reduce the risk of the at least one tension band cutting into the spinous process(es) over time. In some embodiments, for example, at least one of the at least one tension band has at least in the region of the first load-bearing surface and / or in the region of the second load-bearing surface a width of at least 2 mm, preferably at least 5 mm. As an example, a width from 5 mm to 20 mm, e.g. from 5 mm to 15 mm, was found to be particularly suitable. Optionally, lower ranges or widths may be chosen, e.g. for children.

[0130] In some embodiments, the at least one tension band has a width of at least 2 mm, preferably at least 5 mm.

[0131] Depending on the application, the system may optionally comprise a tensioning unit configured for applying a tension to the at least one tension band in the mounted position. For example, the tensioning unit may be used for applying the pre-tension to the at least one tension band in the mounted position. The tensioning unit may for example be part of the first lock described above or it may be provided as a separate unit.

[0132] Depending on the application, it could be advantageous to maintain or control a dorsal position of the at least one tension band, e.g. to prevent accidental slippage or other accidental movement of the at least one tension band in the dorsal direction. As an example, slippage of the at least one tension band along the cranial edge and / or along theP29158PC00 06.02.2026

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[0134] caudal edge could result in an undesired alteration of the secondary load path and, consequently, of the entire load balance of the system. A further reason to secure a position in dorsal direction could arise in situations where the spinal segment includes multiple different vertebrae and / or a spinal segment with significant curvature. In these cases, it may need to be necessary to guide the tension band along with the curvature of the spine, so that the tension band can be essentially parallel to the first connecting rod, which would in these cases also be curved. Other reasons for dorsal position control may also exist.

[0135] Regardless of the specific reasons, in some embodiments, the system comprises a guide structure for guiding the at least one tension band in the mounted position. The guide structure may e.g. comprise a stop surface for contacting the at least one tension band in the mounted position.

[0136] Depending on the application, the stop surface may e.g. face in the ventral direction and / or in the dorsal direction. For example, when facing in the ventral direction, the stop surface may e.g. act as a stop to block displacement of the at least one tension band in dorsal direction. Conversely, when the stop surface faces in the dorsal direction, the stop surface may e.g. act as a stop to block displacement of the at least one tension band in ventral direction.

[0137] It is advantageous to fixate the stop surface with respect to the first stiffener. As an example, relative displacement of the stop surface with respect to the first stiffener may be essentially blocked. This can be used to ensure that a dorsal position of the tension band with respect to the first stiffener is controlled, at least with respect to displacement of the tension band in dorsal and / or ventral direction.P29158PC00 06.02.2026

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[0139] Depending on the application, different construction variants can be envisioned for the guide structure. In some embodiments, the guide structure is attached to the first connecting rod or to the at least one rung. Irrespective of the specific attachment, in some embodiments, the guide structure comprises a guide rail and / or a guide hook and / or a guide loop.

[0140] Depending on the application, different stop surfaces may be used. In some embodiments, the stop surface is convex in a cross-section orthogonal to a longitudinal direction of extension of the first connecting rod.

[0141] Thus, in some embodiments, the system further comprises a dorsal position retainer configured to be interconnected to the at least one tension band in the mounted position and configured for preventing displacement of the at least one tension band with respect to the spinal segment in dorsal direction. For example, the dorsal position retainer could be realized as a loop or hook that maintains a dorsal position of the at least one tension band. The loop or hook may e.g. retain or otherwise receive the at least one tension band in the mounted position.

[0142] As outlined above, the system described herein comprises at least one tension band and different possible embodiments of the tension band may be used in isolation or in combination with each other. The first tension band, which is one possible embodiments of the at least one tension band, has already been described. In the following, the second, third, fourth and firth tension band will be described in further detail. As explained before, the different tension bands may be provided independently of each other. In other words, the system may comprise one or more of the following: the first tension band, the second tension band, the third tension band, the fourth tension band and the fifth tension band (and optionally even further tension bands). Thus, the numerical indicators first, second,P29158PC00 06.02.2026

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[0144] third, fourth and fifth only serve to distinguish between a selection of possible embodiments of the tension indicator, but do not imply a hierarchy or dependency.

[0145] In some embodiments, the at least one tension band comprises a second tension band. The second tension band interconnects in the mounted position a spinous process of the upper vertebra and a spinous process of a vertebra above the upper vertebra.

[0146] Alternatively or in combination, in some embodiments, the at least one tension band comprises a third tension band. The third tension band interconnects in the mounted position a spinous process of the lower vertebra and a spinous process of a vertebra below the lower vertebra.

[0147] Depending on the application, the system may optionally comprise at least one rung attached in the mounted position to the first stiffener (and, optionally, also to the second stiffener). The rung may e.g. be used as a point of attachment or interconnection for at least one of the at least one tension bands.

[0148] In some embodiments, the at least one tension band comprises a fourth tension band interconnecting in the mounted position a spinous process of a vertebra above the upper vertebra and a first rung attached to the first stiffener. The first rung may e.g. be arranged in dorsal direction adjacent to the upper vertebra.

[0149] Alternatively or in combination, in some embodiments, the at least one tension band comprises a fifth tension band interconnecting in the mounted position a spinous process of a vertebrae below the lower vertebra and a second rung attached to the first stiffener. The second rung may e.g. be arranged in dorsal direction adjacent to the lower vertebra.

[0150] Depending on the application, the at least one rung may have different arrangements. In some embodiments, the at least one rung is in the mounted position attached to andP29158PC00 06.02.2026

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[0152] interconnects the first connecting rod and the second connecting rod. Where a first and second rung are provided, the first and second rung may e.g. be interspaced from each other in ventral direction.

[0153] In some embodiments, the rung is arranged between two adjacent spinous processes in the mounted position.

[0154] Depending on the application, the at least one rung may e.g. be used for attachment or interconnection of at least one of the at least one tension band. Thus, in some embodiments, the at least one rung comprises an interface for attaching the at least one tension band to the rung. The interface may e.g. comprise a groove for receiving the at least one tension band. Alternatively or in combination, the interface may in the mounted position e.g. be offset from the first connecting rod in a dorsal direction. The advantages of such an offset have been described herein.

[0155] Depending on the application, the at least one rung may have different shapes, e.g. shapes that enable or are compatible with an offset in dorsal direction. In some embodiments, the at least one rung is bent, U-shaped or V-shaped in a cross-section orthogonal to a longitudinal direction of extension of the first connecting rod in the mounted position.

[0156] Depending on the application, the interface may optionally be used for tensioning of the at least one tension band as well. In some embodiments, e.g., the interface comprises a second lock for holding the at least one tension band. The second lock may e.g. be configured for holding an end of the tension band.

[0157] In some embodiments, in an unlocked state of the second lock the tension band is displaceable with respect to the second lock, wherein in a locked state of the second lock displacement of the tension band away from the second lock is blocked.P29158PC00 06.02.2026

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[0159] In a further aspect, the present disclosure provides for a method for fusing an upper vertebra and a lower vertebra of a spinal segment. The method makes use of the system described herein. Thus, the method comprises the step of providing the system according to any one of the embodiments described herein. The method further comprises the step of mounting the first stiffener to the upper vertebra and to the lower vertebra.

[0160] In embodiments in which the first stiffener comprises a first pedicle screw, a second pedicle screw and a first stiffener, the mounting may, e.g., involve the step of mounting the first pedicle screw to the upper vertebra and mounting the second pedicle screw to the lower vertebra. The mounting may further involve attaching the first connecting rod to the first pedicle screw and to the second pedicle screw, thereby interconnecting the first pedicle screw and the second pedicle screw.

[0161] In embodiments in which the first stiffener comprises a first facet screw and / or a second facet screw, the mounting may, e.g., passing the first facet screw through the first facet joint and / or passing the second facet screw through the second facet joint, thereby interconnecting in the mounted position the upper vertebra and the lower vertebra. The placement may optionally be made ipsilaterally (using an ipsilateral transfacet screw, e.g. following the Boucher technique), or contralaterally (using a contralateral translaminar transfacet screw, e.g. following the Magerl technique).

[0162] The method further comprises interconnecting with the at least one tension band:

[0163] - the spinous process of the upper vertebra and / or the spinous process of the vertebra above the upper vertebra; and

[0164] - the spinous process of the lower vertebra and / or the spinous process of the vertebra below the lower vertebra.P29158PC00 06.02.2026

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[0166] Preferably, the method comprises encircling the spinous process of the upper vertebra and the spinous process of the lower vertebra.

[0167] Preferably, the at least one tension band is arranged such that it is offset in dorsal direction from the first connecting rod.

[0168] Further embodiments of the method follow from the embodiments described herein in the context of the system. More specifically, the embodiments described herein in the context of the system are generally also embodiments of the method, unless clearly indicated otherwise or unless the context clearly dictates otherwise.

[0169] To facilitate understanding of the present disclosure, the present disclosure (hereinbefore and hereinafter) is described in the context of a mounted position. It is understood that embodiments relating to the system describe the system per se, irrespective of its intended use. Therefore, embodiments that are described herein by explaining a function or an intended use of the system or a component of the system in the mounted position may optionally be re-phrased as embodiments in which the system or the respective component of the system is configured for performing the respective function or for performing the intended use. As an example, the statement that that “the first pedicle screw is in the mounted position attached to the upper vertebra” may optionally be re-phrased such that “the first pedicle screw is configured to be attached to the upper vertebra in the mounted position”.

[0170] BRIEF DESCRIPTION OF THE DRAWINGS

[0171] The disclosure described herein will be more fully understood from the detailed description given herein below and the accompanying drawings, which should not be considered limiting to the disclosure described in the appended claims. The drawings show:P29158PC00 06.02.2026

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[0173] Fig. 1 shows a prior art system of spinal fusion;

[0174] Fig. 2 shows a first embodiment of the system of the present disclosure from a lateral view;

[0175] Fig. 3 shows the first embodiment of the system of the present disclosure from a dorsal view;

[0176] Fig. 4 shows a further embodiment of the system of the present disclosure from a lateral view;

[0177] Fig. 5 shows a further embodiment of the system of the present disclosure from a lateral view;

[0178] Fig. 6 shows a further embodiment of the system of the present disclosure from a lateral view;

[0179] Fig. 7 illustrates a specific embodiment of the tension band of the system disclosed herein from a perspective dorsal view;

[0180] Fig. 8 illustrates an embodiment of the system from a perspective view in which a tension band is used that is interconnected to a rung;

[0181] Fig. 9 illustrates an embodiment of the system from a dorsal view which comprises a first facet screw and a second facet screw extending in the mounted position essentially in parallel to each other;P29158PC00 06.02.2026

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[0183] Fig. 10 illustrates an embodiment of the system from a dorsal view which comprises a first facet screw and a second facet screw crossing each other when viewed from the dorsal direction in the mounted position.

[0184] DESCRIPTION OF EMBODIMENTS

[0185] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts. Should a reference sign be missing in one drawing reference is made to the other drawings.

[0186] Figure 1 shows a prior art system of spinal fusion in order to illustrate the load imbalances and the ensuing medical complications that are addressed by the system of the present disclosure, which will be described in further detail in Figures 2-6.

[0187] The prior art system is illustrated in Fig. 1 from a lateral view. In the illustrated prior art system, two vertebrae 3, 4 are fused together using pedicle screws and a rod attached to the pedicle screws. In the illustrated system, two pedicle screws are attached to two adjacent vertebrae, and the two pedicle screws are then each attached to the rod. This results in a rather rigid fixation in which, due to the rigidity of the rod and its attachment to the pedicle screws, the rod may be viewed as defining a neutral axis with respect to flexion and extension.P29158PC00 06.02.2026

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[0189] Furthermore, to install the pedicle screws and the rod, a surgeon will typically remove at least a portion of the interspinous ligament and of the supraspinous ligament, at least in the region of the two instrumented vertebrae, as illustrated in Fig. 1. Even if care is taken to minimize resection of the interspinous ligament 131 and the supraspinous ligament 132, the posterior midline structures 13 will typically suffer some damage or at least alteration of their biomechanical properties as a result of the implantation of the pedicle screws and the pedicle rod. This ultimately weakens the posterior load path defined by the interspinous ligament and the supraspinous ligament and, in particular, reduces the capacity of the posterior load path to withstand or tolerate tensile loads.

[0190] As illustrated by the arrows, during flexion, the vertebral bodies experience compressive forces and the posterior midline structures (including in particular the interspinous ligament and the supraspinous ligament) experience tensile forces. In a healthy, unharmed spine, there is a balance between the load-bearing properties of the vertebral bodies and the load-bearing properties of the posterior midline structures. However, as illustrated in Fig. 1 , if the posterior midline structures have been harmed or otherwise impaired due to the spinal fusion procedure, the posterior load path is weakened. Ultimately, the reduced load-bearing capabilities of the posterior midline structures result in higher compressive loads acting on the vertebral bodies, which over time can lead to various complications such as adjacent segment degeneration, kyphosis and many other potential complications.

[0191] To address these challenges, the present disclosure provides a system for establishing an improved load path in a fusion procedure. Some embodiments of this system are illustrated in Figures 2-6 and will be described in further detail in the following sections.

[0192] Figures 2-3 illustrate an embodiment of the system 1 from a lateral view (Fig. 2) and from a dorsal view (Fig. 3). To enhance clarity of the figures and to avoid cluttering, theP29158PC00 06.02.2026

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[0194] interspinous ligament 131 and the supraspinous ligament 132 are shown only in Fig. 2 but not in Fig. 3.

[0195] The illustrated system may be used in a fusion procedure in which an upper vertebra 3 (i.e. a cranial vertebra) and a lower vertebra 4 (i.e. a caudal vertebra) are fused together. The system comprises a first stiffener 5, a second stiffener 12 (not visible in Fig. 2) and a first tension band 7. The first stiffener 5 comprises a first pedicle screw 51 which is attached to the upper vertebra 3, and a second pedicle screw 52 which is attached to the lower vertebra 4. The first stiffener 5 also comprises a first connecting rod 53 which is attached to the first pedicle screw 51 and to the second pedicle screw 52, thereby fusing the upper vertebra 3 and the lower vertebra 4. Similarly, the second stiffener 12 also comprises a third pedicle screw 121 and a fourth pedicle screw 122, and the third and fourth pedicle screws 121 , 122 are each attached to a second connecting rod 123. The second stiffener 12 is arranged on an opposite lateral side of the vertebrae 3, 4, as illustrated in Fig. 3. Taken together, the first stiffener 5 and the second stiffener 12 together form a primary load path 6 between the upper vertebra 3 and the lower vertebra 4.

[0196] T o provide an improved overall load path, the system 1 further comprises the first tension band 7. In the illustrated embodiments, the first tension band 7 extends from a spinous process of a vertebra 9 above the upper vertebra 3 to a spinous process 41 of the lower vertebra 4. More specifically, the first tension band 7 forms a closed loop which encircles these two spinous processes in the mounted position. Thereby, the first tension band 7 forms a secondary load path 8 across the upper vertebra 3 and the lower vertebra 4. This secondary load path 8 provides an additional load path in addition to the primary load path 6, which allows a more balanced load distribution across the spinal segment 2.P29158PC00 06.02.2026

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[0198] More specifically, in the illustrated embodiment, the first tension band 7 is arranged offset in dorsal direction from the first stiffener 5 and from the second stiffener 12. Thereby, the first tension band 7 may strengthen the posterior midline structures and increase the ability of the posterior midline to withstand tensile loads. As a result of this, compressive overloads acting on the vertebral bodies 14 post-fusion are minimized or even entirely avoided. This ultimately allows to minimize or even eliminate the risk of complications arising after spinal fusion procedures, such as adjacent segment degeneration, kyphosis, etc. A further advantage of the dorsal offset is that the dorsal offset effectively leads to a leverage effect of the first tension band 7 (due to its distance to the neutral axis that may e.g. be defined by the first stiffener 5 and by the second stiffener 12), which ultimately means that the strengthening effect of the first tension band 7 on the tensile loadbearing capabilities of the posterior midline is particularly high.

[0199] In the illustrated embodiment, the first tension band 7 is arranged essentially parallel to the first stiffener 5 and to the second stiffener 12. This further contributes to a more balanced load distribution across the spinal segment 2 because of an optimal alignment with the axis of tensile load acting on the posterior midline structures. A further advantage of the essentially parallel arrangement is that the leverage effect described above is further optimized.

[0200] In the illustrated embodiments, the first tension band 7 contacts the spinous process of the vertebra 9 above the upper vertebra 3 with a first load-bearing surface 71 of the first tension band 7. Furthermore, the first tension band 7 contacts the spinous process of the lower vertebra 4 with a second load-bearing surface 72 of the first tension band 7. The first tension band 7 may be optimized to provide enhanced load transfer and load distribution between the spinous processes and the first tension band 7. For example, the first tension band 7 preferably has a certain minimum width in the region of the first load-bearing surface 71 and of the second load-bearing surface 72 in order to distributeP29158PC00 06.02.2026

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[0202] the tensile loads across a large surface and reduce the risk of damage, which may e.g. arise if the first tension band 7 is thin and may then e.g. cut into the spinous processes. For example, the minimum width may e.g. be at least 3 mm, preferably at least 5 mm in these regions.

[0203] In the illustrated embodiment, the first tension band 7 also extends further in cranial direction than an upper (i.e. cranial) end of the first connecting rod 531 and also further in dorsal direction than a lower (i.e. dorsal) end of the first connecting rod 532. It is understood that the same also applies with respect to an upper end of the second connecting rod 12 and a lower end of the second connecting rod 12 due to the parallel arrangement of the first stiffener 5 and the second stiffener 12.

[0204] By extending beyond the upper end and beyond the lower end, the load distribution postfusion is enhanced even further. In particular, the risk of local overloads post-fusion is minimized in a transition region between the outermost instrumented vertebrae and their neighboring non-instrument vertebrae, as explained in further detail above.

[0205] Figures 4-6 illustrate further embodiments of the system 1 of the present disclosure. In particular, these figures illustrate that depending on the application, the first tension band 7 may encircle or otherwise interconnect different spinous processes.

[0206] For example, in Fig. 4, the first stiffener 5 fuses an upper vertebra 3 and a lower vertebra 4, and the first tension band 7 encircles the spinous processes of these two vertebrae, i.e. the spinous process 41 of the lower vertebra 4 and the spinous process 31 of the upper vertebra 3. In other words, the first tension band 7 only encircles instrumented vertebrae in Fig. 4.

[0207] By contrast, in Figs. 5 and 6, the first tension band 7 also encircles non-instrument vertebrae. For example, in Fig. 5, the first tension band 7 encircles a spinous process of aP29158PC00 06.02.2026

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[0209] vertebra 8 above the upper vertebra 3 and the spinous process 41 of the lower vertebra 4. In Fig. 6, the first tension band encircles the spinous process of a vertebra 8 above the upper vertebra 3 and a spinous process of a vertebra 10 below the lower vertebra 4.

[0210] The embodiments shown in Figs. 4-6 may be chosen for different applications. As an example, in cases where the spinal fusion procedure is performed with only minimal damage to the posterior midline structures, it may suffice to interconnect the spinous processes of the instrumented vertebrae, as illustrated in Fig. 4. However, in cases where the posterior midline structures have been impacted more significantly during the procedure, it may be more advantageous to make use of the variants shown in Figs. 5 or 6 in which the first tension band 7 is at least partly interconnected to non-instrument vertebrae arranged adjacent to the upper or lower instrumented vertebrae. For example, these variants may be advisable in order to strengthen the transition region between the upper vertebra 3 and the vertebrae 9 above the upper vertebra 4, and / or the transition region between the lower vertebra 4 and the vertebrae 10 below the lower vertebra 4.

[0211] A further application in which the variants shown in Figs. 5 and 6 may be chosen are cases where the spinous processes of at least some of the instrumented vertebrae have been removed (not illustrated in Figs. 5 and 6), as is common practice in many spinal fusion procedures. In these cases, because the respective spinous processes of the instrumented vertebrae may no longer be available, it may be inevitable to choose the spinous processes of adjacent vertebrae instead.

[0212] Figure 7 illustrates a specific embodiment of the first tension band 7 of the system 1. Depending on the application, the first tension band 7 may have different arrangements and shapes. For example, in the embodiment shown in Fig. 7, the first tension band 7 forms a closed loop for encircling in the mounted position two spinous processes.P29158PC00 06.02.2026

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[0214] As illustrated in Fig. 7, the first tension band 7 may extend in a longitudinal direction of the first tension band from a first end 73 to a second end 74. In the mounted position, the first end 73 may be interconnected to the second end 74 in different ways, e.g. through a first lock 11 , as illustrated in Fig. 7. More specifically, the first end 73 and the second end 74 are each connected to a suture which in turn is connected to the first lock 11 . In the illustrated embodiment, the first lock 11 is realized as a button.

[0215] The first lock 11 is interconnected in the mounted position to the first end 73 and to the second 74 to maintain the first tension band 7 in a pre-tension with respect to a neutral position of the spinal segments 2, thereby providing an elastic resistance to flexion beyond the neutral position. Usually the first lock 11 is in an unlocked (open) state displaceable along a length of the first end 73 and / or along a length of the second end 74. In a locked (closed) state a displacement of the first lock 11 along the length of the first end 73 and / or along the length of the second end 74 is blocked in at least one direction. Thereby, the first lock 11 may be used to set and maintain a pre-tension on the first tension band 7. Optionally, the first lock 11 may also be used to re-tension the first tension band 7 after implantation, e.g. after a settling process and / or after a few weeks, months or even years in order to compensate changes in the load circumstances occurring over time.

[0216] Figure 8 illustrates an embodiment of the system 1 in which a tension band is used that does not span the entire spinal segment and which is interconnected to a rung.

[0217] More specifically, a spinal segment is shown in which four vertebrae are instrumented, including an upper vertebra 3 and a lower vertebra 4. As part of the instrumentation, a first stiffener 5 and an oppositely arranged second stiffener 12 are used, each including a respective connecting rod 53, 123. The first and second connecting rod 53, 123 are also interconnected through a first rung 16 and another rung. More specifically, the rungsP29158PC00 06.02.2026

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[0219] are each attached to the first connecting rod 53 and to the second connecting rod 123, in the illustrated embodiment through the respective pedicle screws of the first stiffener 5 and of the second stiffener 12. The first rung 16 is also bent in dorsal direction.

[0220] Furthermore, the system 1 illustrated in Fig. 8 comprises a tension band 15 which is labelled herein as fourth tension band 15. However, as explained above, the numerical indicator “fourth” merely serves to distinguish it from the other tension band embodiments described herein. It does not imply that the system must also comprise a first, second and third tension band, as is evident form the embodiment of the system shown in Fig.

[0221] 8 which comprises only the fourth tension band 15.

[0222] The fourth tension band 15 interconnects the first rung 16 and a spinous process of a vertebra 9 above the upper vertebra 3. More specifically, the fourth tension band 15 forms a semi-loop around the spinous process of the vertebra 9 above the upper vertebrae 3, and a semi-loop around the first rung 16. Importantly, the fourth tension band 15 extends essentially parallel to the first and second connecting rod 53, 123, thereby allowing for a balanced load distribution as explained hereinbefore. Furthermore, because the first rung 16 is bent in dorsal direction, the fourth strap 15 is also offset in dorsal direction with respect to the first and second connecting rod 53, 123. This, in turn, serves to improve the leverage, as also explained in detail hereinbefore.

[0223] Figures 9 and 10 illustrate embodiments of the system 1 which comprise a first facet screw 17 and a second facet screw 18. As illustrated, the first facet screw 17 passes in the mounted position through a first facet joint 21 between the upper vertebra 3 and the lower vertebra 4, thereby interconnecting in the mounted position the upper vertebra 3 and the lower vertebra 4. Similarly, the second facet screw 18 passes in the mounted position through a second facet joint 22 between the upper vertebra 3 and the lower vertebra 4, thereby interconnecting in the mounted position the upper vertebra 3 and theP29158PC00 06.02.2026

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[0225] lower vertebra 4. Together, the first and second facet screws 17, 18 form a primary load path 6 between the upper vertebra 3 and the lower vertebra 4 in the embodiments in Figs. 9 and 10.

[0226] To provide an improved overall load path, the systems 1 illustrated in Figs. 9 and 10 each further comprise a first tension band 7. In the embodiment illustrated in Fig. 10, the first tension band 7 extends from a spinous process of the upper vertebra 3 to a spinous process of the lower vertebra 4. In the embodiment illustrated in Fig. 9, the first tension band 7 extends from a spinous process of a vertebra 9 above the upper vertebra 3 to a spinous process of the upper vertebra 3. In both cases, more specifically, the first tension band 7 forms a closed loop which encircles the respective two spinous processes in the mounted position. Thereby, the first tension band 7 forms a secondary load path, which provides a further load path in addition to the primary load path, which allows a more balanced load distribution across the spinal segment.

[0227] The embodiments shown in Figs. 9-10 have several advantages. For example, the respective systems preserve a considerable range of motion, while still providing sufficient spinal stabilization. Furthermore, by relying on a first facet screw 17 and a second facet screw 18 only, the system 1 has a low implant density and is easy to implant because only few surgical maneuvers are required.

[0228] The embodiments shown in Figs. 9-10 differ from each other in the type of facet screws used. In the embodiment shown in Fig. 9, the Boucher technique has been used and the first facet screw 17 and the second facet screw 18 are both ipsilateral transfacet screws. Thus, in Fig. 9, the first and second facet screws 17, 18 extend in the mounted position essentially parallel to each other when viewed from a dorsal direction.P29158PC00 06.02.2026

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[0230] In the embodiment shown in Fig. 10, the Magerl technique has been used and the first facet screw 17 and the second facet screw 18 are both contralateral translaminar transfacet screws. Thus, as illustrated in Fig. 10, in the mounted position, the first and second facet screws 17, 18 cross each other when viewed from the dorsal direction.

[0231] It is understood that Figs. 9-10 show the respective embodiments from a distal view and that dashed lines represent structures which are not visible from said perspective.P29158PC00 06.02.2026

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[0233] LIST OF DESIGNATIONS

[0234] 1 System 73 First end of the tension band 2 Spinal segment 74 Second end of the tension 21 First facet joint band

[0235] 22 Second facet joint 8 Secondary load path 3 Upper vertebra 9 Vertebra above the upper 31 Spinous process of upper vertebra

[0236] vertebra 10 Vertebra below the lower 4 Lower vertebra vertebra

[0237] 41 Spinous process of lower 11 First Lock

[0238] vertebra 12 Second stiffener

[0239] 5 First stiffener 121 Third pedicle screw

[0240] 51 First pedicle screw 122 Fourth pedicle screw 52 Second pedicle screw 123 Second connecting rod 53 First connecting rod 13 Posterior midline structures 531 Upper end of the first 131 Interspinous ligament connecting rod 132 Supraspinous ligament 532 Lower end of the first 14 Vertebral bodies connecting rod 15 Fourth tension band 6 Primary load path 16 First Rung

[0241] 7 First tension band 17 First facet screw

[0242] 71 First load-bearing surface 18 Second facet screw

[0243] 72 Second load-bearing surface

Claims

P29158PC00 06.02.202644 / 50PATENT CLAIMS1 . System (1) for establishing interplaying load paths in a spinal fixation procedure of a spinal segment (2) between an upper vertebra (3) and a lower vertebra (4) for minimizing post-fixation overloads, the system (1) comprising:a. A first stiffener (5) for forming a primary load path (6) between the upper vertebra (3) and the lower vertebra (4), wherein the first stiffener (5) is attached to and interconnects in the mounted position the upper vertebra (3) and the lower vertebra (4); and:b. At least one tension band (7) for forming a secondary load path (8) across the upper vertebra (3) and the lower vertebra (4).

2. System (1 ) according to claim 1 , wherein the at least one tension band comprises a first tension band interconnecting in the mounted position:a. a spinous process (31 ) of the upper vertebra (3) and / or a spinous process of a vertebra (9) above the upper vertebra (3); andb. a spinous process (41 ) of the lower vertebra (4) and / or a spinous process of a vertebra (10) below the lower vertebra (4).

3. System (1) according to claim 2, wherein the first tension band (7) directly transfers tension loads between the upper vertebra (3) of the spinal segment (2) and the lower vertebra (4) of the spinal segment (2) in the mounted position.

4. System (1 ) according to any one of the previous claims, wherein the at least one tension band (7) is not directly connected to the first stiffener (5).P29158PC00 06.02.202645 / 505. System (1 ) according to any one of the previous claims, wherein the at least one tension band (7) is in the mounted position offset from the first stiffener (5) in a dorsal direction and / or in a lateral direction.

6. System (1 ) according to any one of the previous claims, wherein the at least one tension band (7) extends in the mounted position beyond an upper end (531) of the first stiffener (5) in a cross-section orthogonal to the dorsal direction; and / or the at least one tension band (7) extends in the mounted position beyond a lower end (532) of the first stiffener (5) in a cross-section orthogonal to the dorsal direction.

7. System (1) according to any one of the previous claims, wherein at least one of the at least one tension band (7) extends in a longitudinal direction of the respective tension band (7) from a first end (73) to a second end (74) configured to be interconnected in the mounted position to the first end (73) for forming a closed loop.

8. System (1 ) according to claim 7 and 2, wherein the first tension band (7) forms the closed loop configured to encircle in the mounted position:a. the spinous process (31 ) of the upper vertebra (3) or the spinous process of a vertebra (9) above the upper vertebra; andb. the spinous process (41 ) of the lower vertebra (4) or the spinous process of a vertebra (10) below the lower vertebra (4).

9. System (1) according to claim 7 or 8, wherein the closed loop formed by the respective tension band (7) is in its circumference adjustable.P29158PC00 06.02.202646 / 5010. System (1 ) according to any one of claims 7-9, further comprising a first lock (11) interconnecting in the mounted position the first end (73) and the second end (74) of the at least one tension band (7).

11. System (1) according to claim 10, wherein in an unlocked state of the first lock (11) the first end (73) and the second end (74) of the respective tension band (7) are displaceable towards each other, wherein in a locked state of the first lock (11) displacement of the first end (73) and the second end (74) of the respective tension band (7) away from each other is blocked.

12. System (1 ) according to any one of the previous claims, wherein the at least one tension band (7) is pre-tensioned with respect to a neutral position of the spinal segment (2) in the mounted position.

13. System (1 ) according to any one of the previous claims, wherein the first stiffener (5) comprises:i. A first pedicle screw (51) in a mounted position attached to the upper vertebra and a second pedicle screw (52) in the mounted position attached to the lower vertebra (4); andii. A first connecting rod (53) in the mounted position attached to and interconnecting the first pedicle screw (51 ) and the second pedicle screw (52) to each other; andWherein the at least one tension band (7) is arranged in the mounted position essentially parallel to the first connecting rod (53).P29158PC00 06.02.202647 / 5014. System (1) according to claim 13, further comprising a second stiffener (12) for forming together with the first stiffener (5) the primary load path (6) between the upper vertebra (3) and the lower vertebra (4), the second stiffener (12) comprising:a. A third pedicle screw (121) in a mounted position attached to the upper vertebra (3) and a fourth pedicle screw (122) in the mounted position attached to the lower vertebra (4); andb. A second connecting rod (123) in the mounted position attached to and interconnecting the first pedicle screw (121) and the second pedicle screw (122) to each other.

15. System (1) according to claim 14, wherein the first stiffener (5) and the second stiffener are in the mounted position arranged parallel to each other.

16. System (1) according to any one of claims 14 or 15, wherein the first stiffener (5) and the second stiffener are in the mounted position arranged on opposite lateral sides of the upper vertebra (3) and of the lower vertebra (4).

17. System (1 ) according to any one of claims 14-16, wherein the at least one tension band (7) is arranged in the mounted position between the first connecting rod (53) and the second connecting rod in a cross-section orthogonal to the dorsal direction.

18. System (1) according to any one of claims 13-17, further comprising at least one rung (16) attached in the mounted position to the first stiffener and optionally to the second stiffener.

19. System (1) according to claim 18, wherein the at least one tension band comprises:P29158PC00 06.02.202648 / 50a. a fourth tension band (15) interconnecting in the mounted position a spinous process of a vertebra above the upper vertebrae and a first rung (16) attached to the first stiffener; and / orb. a fifth tension band interconnecting in the mounted position a spinous process of a vertebrae below the lower vertebra and a second rung attached to the first stiffener.

20. System (1 ) according to any one of claims 1 -12, wherein the first stiffener (5) comprises:a. a first facet screw (17) passing in the mounted position through a first facet joint (21) between the upper vertebra (3) and the lower vertebra (4), thereby interconnecting in the mounted position the upper vertebra (3) and the lower vertebra (4); andb. a second facet screw (18) passing the mounted position through a second facet joint (22) between the upper vertebra (3) and the lower vertebra (4), thereby interconnecting in the mounted position the upper vertebra (3) and the lower vertebra (4).21 . System (1 ) according to claim 20, wherein the first facet screw (17) and the second facet screw (18) are angled with respect to each other at less than 50° in the mounted position when viewed from the dorsal direction.

22. System (1 ) according to claim 20, wherein the first facet screw (17) and the second facet screw (18) cross each other when viewed from the dorsal direction in the mounted position.P29158PC00 06.02.202649 / 5023. System (1 ) according to any one of the previous claims, wherein the at least one tension band comprises:a. a second tension band (15) interconnecting in the mounted position a spinous process (31) of the upper vertebra (3) and a spinous process of a vertebra (9) above the upper vertebra (3); and / orb. a third tension band interconnecting in the mounted position a spinous process (41 ) of the lower vertebra (4) and a spinous process of a vertebra (10) below the lower vertebra (4).

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