SYSTEMS FOR DAMPING INCREASED SPHERICAL BEND LOADS AFTER MERGER

Description

CLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 632,039, filed on February 19, 2018.BACKGROUND

[0002] Kyphosis is one example of a post-surgical complication following fusion of the spine that can lead to compromised patient outcomes and revision surgery. In one example, Proximal junctional kyphosis (PJK) can be defined as an increase in kyphosis of 10 degrees or more, relative to the preoperative measurements, between the inferior endplate of the uppermost instrumented vertebra (UIV) and the superior endplate of the vertebra two levels above the UIV. The reported incidence of PJK is significant and may lead to one or more of radiographic changes, aesthetic changes, back pain, disability, and, ultimately, proximal junction failure.

[0003] US 2016 / 235447 discloses a spinal fixation construct for aligning vertebral bodies. The spinal fixation construct includes a bone screw, a spinal rod, a flexible member, and a fixation member. The spinal rod is formed from a first material having a first modulus of elasticity. The flexible member is coupled to the spinal rod and is formed from a second material having a second modulus of elasticity different from the first modulus of elasticity. The fixation member includes a threaded body portion and a head portion defining a hole therethrough. A portion of the flexible member extends through the hole of the head portion.SUMMARY

[0004] The present invention provides a fusion system, as defined in claim 1. Further optional features of the invention are defined in the dependent claims. Methods are described herein but the methods are not claimed.

[0005] Improving spinal fusion patient outcomes by attenuating hypermobilization that may be associated with increased post-operative flexion loads of the spine proximal to the terminal instrumented vertebra may be desirable. Described herein are various devices, systems, methods, and embodiments that may include a transition member used to attenuate hypermobilization in the spine proximal to instrumented vertebrae. The transition member includes a tension component. The tension component is coupleable to a fused vertebra of a plurality of fused vertebra or a fusion implant and to an adjacent unfused vertebra. The various devices, systems, methods, and embodiments may also include the fusion implant coupleable to the plurality of fused vertebra.

[0006] Further described herein is a method that may include steps such as selecting a tension component of a transition member, coupling the transition member to a fusion implant or an underlying instrumented vertebra, coupling the tension component to the transition member, tensioning the tension component to a selected value, coupling the tension component to an adjacent unfused vertebra, and modulating a flexion range of motion of the adjacent unfused vertebra with the transition member as a function of the selected value of tension of the tension component.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various arrangements discussed in the present document. Figure 1A illustrates a side, cut-away view of normal flexion load on an uninstrumented spine. Figure 1B illustrates a side, cut-away view of an increased flexion load on an instrumented spine that has undergone posterior fusion. Figure 2A is a perspective view of a first arrangement and Figure 2B illustrates the arrangement of Figure 2A in an operational configuration. Figure 3 is a flow chart illustrating a method. Figure 4 is a schematic, side, cut-away view of a fused spine. Figure 5 is a schematic, side, cut-away view of a fused spine including a transition member according to an exemplary embodiment. Figure 6 is a schematic of a fused spine including two transition members according to an exemplary embodiment. Figure 7 is a schematic of a fused spine including a hand tied suture loop. Figure 8 illustrates a perspective side view of a fused spine specimen. Figure 9 is a radiographic representation of the fused spine specimen of Figure 8. Figure 10 illustrates a fused spine specimen also including a transition member. Figure 11 illustrates a fused spine specimen with a hand tied suture loop. Figure 12 illustrates certain aspects of the biomechanical test setup used to test the various spine specimen. Figure 13 shows an exemplary tensioner. Figure 14A is a graph that illustrates the range of motion of the motion segments under extension / flexion of different test specimens relative to a native spine loaded at 4 Nm. Figure 14B shows the flexion range of motion values of the T9-T10 segments shown in Figure 14A and Figure 14C shows the extension range of motion values of the T9-T10 segments shown in Figure 14A. Figure 15 is a graph that illustrates the range of motion of the motion segments under lateral bending of different test specimens relative to a native spine loaded at 4 Nm. Figure 16 is a graph that illustrates the range of motion of the motion segments under axial rotation of different test specimens relative to a native spine loaded at 4 Nm. Figure 17A is a perspective view of an arrangement and Figure 17B illustrates the arrangement of Figure 17A in an operational configuration. Figure 18 is a flow chart illustrating another method. DETAILED DESCRIPTION

[0008] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0009] Spinal fusion involves immobilizing two or more vertebrae, to correct some form of deformity or degeneration, such as disc degeneration or correction of spondylosis. Implants such as pedicle screws and connecting rods are commonly used to secure the two or more vertebrae, while bone grows between the vertebral end plates. An interbody implant is also often used to maintain the space between the vertebral bodies and assist in encouraging bone growth. Spinal fusion reduces motion between the fused vertebrae, which is known to induce additional stresses on adjacent unfused vertebra. The present disclosure involves an implant, discussed herein as a transition member, to assist in transitioning some of the new loads experienced by the unfused vertebra onto the fusion implants, such as the connecting rods, screws or interspinous devices. As discussed in detail below, the transition member can include a clamp or similar mechanism secured to the fusion implants (e.g., the connecting rod) and a flexible member connected to an adjacent unfused vertebra and the clamp.

[0010] The present disclosure provides for various devices, systems, methods, and embodiments that may include a transition member. The transition member may include a tension component. The tension component may be coupleable to a fused vertebra of a plurality of fused vertebra or a fusion implant and to an adjacent unfused vertebra. The tension component is tensionable to a selected value. The tension component modulates a flexion range of motion of the adjacent unfused vertebra as a function of the selected value of tension of the tension component. The transition member attenuates spinal flexion loads on the adjacent unfused vertebra post-operatively, by transmitting a portion of the loads onto the fused vertebrae through the transition member. The various devices, systems, methods, and embodiments may also include the fusion implant(s) coupleable to the plurality of fused vertebra. Such devices, systems, methods, and embodiments may, among other things, improve spinal fusion patient outcomes by attenuating hypermobilization that may be associated with increased post-operative flexion loads of the spine proximal to the terminal instrumented vertebra. Attenuating hypermobilization by supporting the spine against increased flexion loads as an adjunct to fusion surgery may mitigate or prevent the development of post-surgical complications following fusion of the spine that may include proximal junctional kyphosis (PJK) and distal junctional kyphosis (DJK).

[0011] Figure 1A illustrates a normal flexion load F n on an uninstrumented spine and Figure 1B illustrates an increased flexion load F i on an instrumented spine that has undergone posterior fusion. The increased loading experienced by the instrumented spine may be due to the stiffness of the fusion implant (or fusion construct) or to iatrogenic damage to posterior ligament complex. Such increased loading can lead to hypermobility of the spine proximal to the terminal instrumented vertebra of the fusion implant.

[0012] One example of a system 100 according to the present disclosure is illustrated in Figure 2. The system 100 includes a fusion implant (or fusion construct) 102 coupleable to a plurality of fused vertebra and a transition member 104. The transition member 104 can include a tension component 106 coupleable to a fused vertebra 108 of the plurality of fused vertebra and an adjacent unfused vertebra 110. As will be discussed further below, the tension component 106 can include any suitable flexible elongate member, such as a tether, a cord, a band, or a flexible rod. (As used herein, the terms tethers, cords, and bands can be used interchangeably and simply refer to any suitable flexible, elongate member.) The tension component 106 is tensionable to a selected value and can modulate a flexion range of motion (ROM) of the adjacent unfused vertebra 110 as a function of the selected value of tension of the tension component 106. One embodiment may have a tension value for the tension component 106 of in ranges including 200 to 400 Newtons (N) or 250 to 350 N, other ranges may be utilized. The transition member 104 can attenuate spinal flexion loads on the adjacent unfused vertebra 110 post-operatively by transferring at least a portion of the load through the transition member onto the fusion construct. Furthermore, the system 100 can include a second transition member 104' identical to the first transition member 104 that is positioned opposite the first transition member 104 relative to the medial plane of the spine in order to effect bilateral attenuation of flexion loads on the adjacent unfused vertebra 110. Transition member 104 (or transition members 104, 104') can be configured to attenuate PJK or DJK of the adjacent unfused vertebra 110 based on whether the adjacent vertebra 110 is cranial or caudal to the underlying instrumented vertebra 108.

[0013] In one example, the transition member 104 can comprise a clamp 112 securable to a rod 114 of the fusion component 102 and to the tension component 106. Here, the tension component 106 can include any suitable flexible, elongate member that is tensionable to the selected value. In the example utilizing a flexible elongate member, the tension component 106 can be tensioned via a tensioning instrument, such as the one discussed below in reference to FIG. 12. In one example, the tension component 106 can be a polyester band. The tension component 106 can be coupleable to the adjacent unfused vertebra 110 sublaminarly or to a spinous process or to the transverse process of the adjacent unfused vertebra 110. The pedicle screw replacement Universal Clamp ®< implant distributed by Zimmer Biomet Spine, Inc. (Westminster, CO) can be used as a transition member with certain modifications in how the flexible member engages the vertebra.

[0014] Figure 3 is a flowchart illustrating a method 300 according to an example embodiment. The method 300 can be performed as an adjunct to spinal fusion subsequent to implantation of a fusion implant 102, such as shown in Figure 3. The method 300 can include operations such as selecting a tension component 106 of a transition member 104, coupling at least a portion of the transition member 104 to an underlying instrumented vertebra 108 of a plurality of underlying instrumented vertebra of a fusion implant 102, coupling the tension component 106 to the transition member 104, tensioning the tension component 106 to a selected value, coupling the tension component 104 to an adjacent unfused vertebra 110 under the selected value of tension, and modulating a flexion range of motion of the adjacent unfused vertebra 110 with the transition member 104 as a function of the selected value of tension of the tension component 106. The method 300 can also include provisionally coupling the tension component 106 to the adjacent unfused vertebra 110 prior to tensioning the tension component 106 to the selected value.

[0015] In an example, system 100 described above can be implanted as follows. The method 300 can begin at 302 with the selection of a tension component 106 of a transition member 104. In one example, the tension component 106 selected can be a polyester band and the transition member 104 can be a clamp. In another example, the tension component 106 can be a flexible rod.

[0016] At 304, the tension component 106 can be provisionally coupled to the transition member 104. In one example, a first end of the band can be threaded through an aperture in the clamp.

[0017] At 306, the tension component 106 can be provisionally coupled to an adjacent uninstrumented vertebra 110. In one example, the band can be provisionally coupled to the adjacent uninstrumented vertebra 110 sublaminarly by extending a free second end the band from the clamp to the adjacent uninstrumented vertebra 110 and passing the free second end of the band under the lamina in a caudal-to-cephalad direction back to the clamp, where the second end can be coupled to the clamp. In another example, the band can be provisionally coupled to the adjacent uninstrumented vertebra 110 by passing a free second end of the band from the clamp around a transverse process of the adjacent uninstrumented vertebra 110 and back to the clamp, where the second end can be coupled to the clamp. In some examples, a second clamp can be used, and the second end is threaded into the second clamp. In such examples, the first clamp and second clamp can be positioned on opposing fusion constructs fixed along either side of a midline of the fused vertebrae (such as shown in Figures 2B and 10).

[0018] At 308, the transition member 104 can be coupled to a fused vertebra 108 of a plurality of fused vertebra of a fusion implant 102. In one example, the transition member 104 can be coupled to a rod of the fusion implant 102. The underlying vertebra 108 can be proximate the upper end or the lower end of the fusion implant 102 and on the same side of the fusion implant 102 as the adjacent uninstrumented vertebra 110.

[0019] At 310, the tension component 106 can be tensioned to a selected value. In one example, a tensioner (such as the tensioner depicted in Figure 13) can be used to tension the band by pulling at least one free end of the band through the clamp to reduce the length of the loop portion of the band coupled to the adjacent uninstrumented vertebra 110. In an example, the selected value of tension can be within ranges such as from 200 to 400 N or from 250 to 350 N. However, a skilled artisan will appreciate that different selected values can be desirable based on a number of additional factors such as, but not limited to, the characteristics of the selected tension component 106 and the weight of the patient.

[0020] At 312, the tension component 106 can be secured under the selected value of tension and the transition member 104 can be fully secured to the fusion implant 102 in a final operative configuration as illustrated in Figure 5. In one example, a set screw 116 can be advanced into the clamp to secure the band within the clamp and secure the clamp to the rod. Accordingly, a flexion range of motion of the adjacent unfused vertebra 110 can be modulated with the transition member 104 as a function of the selected value of tension of the tension component 106. The flexion range of motion of the adjacent unfused vertebra 110 can be modulated to attenuate proximal junction kyphosis or distal junction kyphosis (as the case may be) of the adjacent unfused vertebra 110.

[0021] At 314, method steps 302-312 can optionally be repeated on the opposite side of the spine to effect bilateral treatment.

[0022] At 316, method steps 302-314 can optionally be repeated to further modulate the flexion range of motion of the adj acent uninstrumented vertebra 110 by coupling a second fused vertebra of the plurality of fused vertebra of the fusion implant to the underlying vertebra 108 as illustrated in Figure 6.

[0023] In Figures 17A and 17B, a system 200 can be similar to the system 100 described above but with a number of key differences discussed below. The transition member 204 can comprise a tension component 206 coupleable to a fused vertebra 208 of the plurality of fused vertebra and an adjacent unfused vertebra 210. The tension component 206 can comprise any suitable flexible elongate member, such as a tether, a cord, a band, or a flexible rod. The transition member 204 can further comprise a first bone implant 212 and a second bone implant 214. The first bone implant 212 can be engageable in one of the underlying vertebra 208 and the adjacent unfused vertebra 210, while the second bone implant 214 can be engageable in the other one of the two vertebrae. The first bone implant 212 can receive a first end of the tension component 206 and, either prior to, during, or subsequent to tensioning the tension component 206 to the selected value, the second bone implant 214 can receive a second end of the tension component 206 (or vice versa). A set screw or other fastener can secure the first and second ends of the tension component 206 under tension in the respective first and second bone implants 212, 214. Furthermore, the system 200 can comprise a second transition member 204' identical to the first transition member 204 that is positioned opposite the first transition member 204 relative to the medial plane of the spine in order to effect bilateral attenuation of flexion loads on the adjacent unfused vertebra 210. The devices, systems, and methods described in U.S. Provisional Patent Application 62 / 551,845, filed on August 2017, can be used as a transition member in accordance with the techniques discussed herein.

[0024] The system 200 described above can be implanted in accordance with a method 400, which includes operations as follows. The method 400 can begin at 402 with the selection of a tension component 206 of a transition member 204. In one example, the tension component 206 selected can be a cord. In another example, the tension component 106 can be a flexible rod.

[0025] At 404, a first bone implant 212 can be implanted in either the underlying vertebra 208 or the adjacent unfused vertebra 210. In one example, the first bone implant and the second bone implant 214 can each comprise pedicle screws.

[0026] At 406, a second bone implant 214 can be implanted in the remaining one of the underlying vertebra 208 and the adjacent unfused vertebra 210.

[0027] At 408, the first end of the tension component 206 can be coupled to either one of the first bone implant 212 and the second bone implant 214.

[0028] At 410, the tension component 406 can be tensioned to a selected value. In one example, a tensioner (such as the tensioner depicted in Figure 13) can be used to tension the tension component by pulling a free end of the tension component until the tension component is tensioned to a selected value. In an example, the selected value of tension can be within ranges such as from 200 to 400 N or from 250 to 350 N. However, a skilled artisan will appreciate that different selected values can be desirable based on a number of additional factors such as, but not limited to, the characteristics of the selected tension component 206 and the weight of the patient.

[0029] At 412, the first end of the tension component 206 can be coupled to either one of the first bone implant 212 and the second bone implant 214 in a final operative configuration as illustrated in Figure 17B. Accordingly, a flexion range of motion of the adjacent unfused vertebra 210 can be modulated with the transition member 204 as a function of the selected value of tension of the tension component 206. The flexion range of motion of the adjacent unfused vertebra 210 can be modulated to attenuate proximal junction kyphosis or distal junction kyphosis (as the case may be) of the adjacent unfused vertebra 210.

[0030] At 414, method steps 402-412 can optionally be repeated on the opposite side of the spine to effect bilateral treatment.Experimental Data

[0031] A study conducted by the inventors of the present disclosure illustrates the efficacy of the examples and embodiments of the present disclosure. The following data demonstrate that use of a transition member adjunct to a spinal fusion can modulate the biomechanical flexion range of motion (ROM) as a function of the tension applied to the band and can effectively attenuate hypermobilization. Also, the level of attenuation can be easily tuned based on the tension applied to the band. Eight human cadaveric thoracolumbar spines were dissected of soft tissue, preserving the osseoligamentous tissues and intervertebral discs, and the T7-L2 segment was isolated. The end vertebrae (T7 and L2) were partially embedded in polymethyl methacrylate (PMMA) bone cement, leaving the discs and ligaments exposed. Small screws were placed in the ventral cortex of each vertebral body, lateral to the anterior longitudinal ligament (ALL), for rigid attachment of 3D motion tracking markers. (See Figures 8, 9, and 12).

[0032] With reference to Figures 4-7 and Figures 8-12, spine specimens were prepared and then instrumented by bilateral placement of pedicle screws at each fusion level (T10-L2) and the pedicle screws were connected with a 5.5mm stainless steel rod. Each specimen was tested under seven conditions: native spine (Native), fused spine (Fused), fused spine plus bilateral clamps having sublaminar tethers tensioned to 250 N at T9-T10 (Tethers 250 N); fused spine plus bilateral clamps having sublaminar tethers tensioned to 350 N at T9-T10 (Tethers 350 N); fused spine plus bilateral clamps having sublaminar tethers tensioned to 250 N at T9-T10 and 350 N at T10-T11 (2 Level Tethers);

[0033] Prior to each biomechanical test, radiographs of each instrumented condition were collected using a C-arm (OEC 9900 Elite; GE Healthcare, Chicago, IL) to measure changes in the lordotic angle at T9-T10 that may have been induced by tensioning the tethers or suture loop. Each specimen was pre-conditioned through 3 cycles of pure moment loading in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) at 4 Nm followed by 8 Nm prior to testing using a servo-hydraulic axial / torsional test frame with dual Bionix ®< Spine Subsystem attachments (Figure 11). The caudal Spine Subsystem was mounted to a passive XY table to eliminate shear and a 10 N axial compressive load was maintained throughout testing to avoid tension. Three cycles of 4 Nm moments were applied to the native spine in FE, LB, and AR. For each instrumentation step, the specimens were loaded to 8 Nm in FE, LB, and AR in 3 cycles each to simulate an increase in loading following pedicle screw instrumentation. The relative rotations of each motion segment were recorded through a 3D motion tracking system and the Euler angles were exported for each principal.

[0034] Rotational data from the third loading cycle in each principal direction was used for analysis. LOESS filtering, with a smoothing factor of 0.01, was used to remove noise from the rotation-time data. The maximum rotations of each motion segment were then extracted to determine the range of motion (ROM) for each principal direction and normalized to the motion of the native spine loaded at 4 Nm. At the levels proximal to the fusion (T7-T10), the ROM data were analyzed using two-way repeated measures ANOVA and Dunnett's test for post-hoc comparisons. Changes in the lordotic angle at T9-T10 with each intervention relative to the Fused condition were calculated and a one-sample t-test was used to check if these changes were significantly different from zero. All data satisfied assumptions of normality according to the Shapiro-Wilk test. Statistics were performed in Prism software and differences were considered statistically significant for p < 0.05.Changes in Sagittal Alignment

[0035] The mean change in lordosis at T9-T10 with the tethers tightened to 250 N and 350 N compared to the Fused condition was 0.7 ± 0.6 degrees and 1.0 ± 0.8 degrees, respectively. The 2-level Tethers resulted in mean changes of 0.5 ± 0.5 degrees. Each of these changes was significantly different from zero (p < 0.05).Flexion-Extension Range of Motion

[0036] With reference to Figures 14A-14C, the surgical interventions primarily affected the flexion and extension ROM at the index level of T9-T10. No significant differences existed between the interventions and Fused condition at T7-T8. At T8-T9, the flexion ROM was significantly increased with the Tethers at 250 N (204% ± 37% of Native) and 350 N (201% ± 38% of Native) compared to Fused (176% ± 30% of Native; p < 0.05)At T9-T10, the flexion ROM was significantly reduced from the Fused state (162% ± 31% of Native) by Tethers at 250 N (85% ± 17% of Native; p < 0.0001), Tethers at 350 N (70% ± 14% of Native; p < 0.0001), and 2-Level Tethers (93% ± 28% of Native; p < 0.0001).

[0037] Tightening the tethers from 250 N to 350 N significantly reduced the flexion ROM by an additional 15% on average (p = 0.0004). The variance associated with the Suture Loop technique was also significantly greater than Tethers at 250 N (p < 0.05) and Tethers at 350 N (p < 0.01). The extension ROM at T9-T10 followed the same trends as the flexion ROM.Lateral Bending and Axial Rotation Range of Motion

[0038] With reference to Figures 15 and 16, the bilateral pedicle screw fixation at T10-T11 with a second level of tethers created a more gradual transition in relative motion at each level from T9-T12 in lateral bending and axial rotation. The rest of the intervention techniques did not affect any of the levels across T7-L2 except for the index level (T9-T10). The ROM in lateral bending at T9-T10 was significantly reduced by Tethers at 350 N (116% ± 10% of Native) compared to Fused (132% ± 9% of Native; p = 0.009), but no other interventions significantly affected the lateral bending ROM. Axial rotation at T9-T10 was not significantly affected by any test condition compared to Fused.

[0039] Each of these non-limiting examples and embodiments can stand on its own, or can be combined in various permutations or combinations with one or more of the other examples.

[0040] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments that may be practiced. These embodiments are also referred to herein as "examples." Such examples can include elements in addition to those shown or described. However, examples are contemplated in which only those elements shown or described are provided. Moreover, embodiments are also contemplated that utilize any combination or permutation of those elements and components shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0041] Described herein is a fusion system for attenuation of increased spinal flexion loads in adjacent levels post-fusion.

[0042] The tension component may be coupleable to an adjacent vertebra sublaminarly.

[0043] The tension component may be coupleable to a spinous process of an adj acent vertebra.

[0044] The tension component may be a flexible elongate member comprised of a polyester band.

[0045] The transition member may include a first bone implant coupleable to the underlying instrumented vertebra and a second bone implant coupleable to the adjacent instrumented vertebra, where the first bone implant receives a first end of the tension component and the second bone implant receives a second end of the tension component.

[0046] The tension member may be a cord.

[0047] The cord may be a polyester cord.

[0048] The flexible rod may be made from a polymer.

[0049] The selected value of tension of the tension component may comprise a range between 250 N and 350 N.

[0050] Adjacent unfused vertebra may be cranial to the underlying instrumented vertebra.

[0051] Adjacent unfused vertebra may be caudal to the underlying instrumented vertebra.

[0052] The adjacent unfused vertebra may include a first adjacent unfused vertebra, where the first transition member is coupleable to a first portion of the fusion implant or its underlying instrumented vertebra and the first adjacent unfused vertebra and the second transition member is coupleable to a second portion of the fusion implant opposite the first portion or its underlying instrumented vertebra and a second adjacent unfused vertebra.

[0053] The tension component may be coupleable to the underlying vertebra via coupling to the fusion implant.

[0054] The transition member may be configured to attenuate proximal junction kyphosis of adjacent unfused vertebra.

[0055] The transition member may be configured to attenuate distal junction kyphosis of adjacent unfused vertebra.

[0056] Further described herein is a method for treating a spine. The method can include the following procedures to utilize the fusion system described herein. The method begins by selecting a tension component of a transition member. The method continues by coupling at least a portion of the transition member to an underlying instrumented vertebra of a plurality of underlying instrumented vertebra of a fusion implant. Next the method includes coupling the tension component to the transition member. Further the method includes tensioning the tension component to a selected value. The method can continue by coupling the tension component to an adjacent unfused vertebra under the selected value of tension. The method can conclude with modulating a flexion range of motion of the adjacent unfused vertebra with the transition member as a function of the selected value of tension of the tension component.

[0057] Optionally the method includes provisionally coupling the tension component to the adjacent unfused vertebra prior to tensioning the tension component to the selected value.

[0058] Optionally the method includes provisionally coupling the tension component to the transition member prior to coupling at least a portion of the transition member to an underlying instrumented vertebra of the plurality of underlying instrumented vertebra of the fusion implant.

[0059] Optionally the method includes coupling the tension component to the transition member comprises coupling a band to a clamp.

[0060] Optionally the method includes coupling at least a portion of the transition member to an underlying instrumented vertebra of the plurality of underlying instrumented vertebra of the fusion implant further comprises coupling the clamp to a rod of the fusion implant.

[0061] Optionally the method includes coupling the tension component to the adjacent unfused vertebra and further comprises sublaminarly coupling the band to the adjacent unfused vertebra.

[0062] Optionally the method includes coupling the tension component to the adjacent unfused vertebra further comprises coupling the band to a spinous process of the adjacent unfused vertebra.

[0063] Optionally the method includes tensioning the tension component to the selected value further comprises tensioning the tension component to a value of 200 to 400 N.

[0064] Optionally the method includes tensioning the tension component to the selected value further comprises tensioning the tension component to a value of 250 to 350 N.

[0065] Optionally the method includes coupling the tension component to the adjacent unfused vertebra further comprises engaging a first bone implant in the adjacent unfused vertebra and coupling a first end of the tension component to the first bone implant.

[0066] Optionally the method includes coupling at least a portion of the transition member to an underlying instrumented vertebra of the plurality of underlying instrumented vertebra of the fusion implant further comprises engaging a second bone implant in the underlying instrumented vertebra.

[0067] Optionally the method includes coupling the tension component to the transition member and further comprises coupling a second end of the tension component to the second bone implant.

[0068] Optionally the method includes selecting the tension component for the tension member further comprises selecting a flexible elongate member.

[0069] Optionally the method further includes selecting the tension component for the tension member further comprises selecting a flexible rod.

[0070] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0071] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim.

Claims

1. A fusion system (100), comprising: a fusion implant (102) coupleable to a plurality of fused vertebra (108); a first transition member (104) comprising a tension component (106), the first transition member (104) coupleable to a first portion of the fusion implant (102) or the underlying instrumented vertebra and an adjacent unfused vertebra on a first side of a medial plane of the spine, wherein the tension component (106) is tensionable to a selected value; and a second transition member (104) comprising a tension component (106), the second transition member (104) coupleable to a second portion of the fusion implant (102) or the underlying instrumented vertebra and the adjacent unfused vertebra on a second side of the medial plane of the spine, wherein the tension component (106) is tensionable to a selected value; wherein the tension components (106) modulate a flexion range of motion of the adjacent unfused vertebrae as a function of the selected values of tension of the tension components; and wherein the transition members (104, 104) attenuate spinal flexion loads on the adjacent unfused vertebrae post-operatively.

2. The fusion system (100) of claim 1, wherein the first transition member (104) further comprises a clamp (112) securable to a rod (114) of the fusion implant (102) and to the tension component (106).

3. The fusion system (100) of claim 2, wherein the first tension component (106) comprises a flexible elongate member or a flexible rod.

4. The fusion system (100) of any one of the preceding claims, wherein the first tension component (106) is coupleable to the adjacent unfused vertebra sublaminarly.

5. The fusion system (100) of any one of the preceding claims, wherein the first tension component (106) is coupleable to a spinous process of the adjacent unfused vertebra.

6. The fusion system of any one of the preceding claims, wherein the selected value of tension of the tension component comprises 200 to 400 Newtons.

7. The fusion system of any one of the preceding claims, wherein the adjacent unfused vertebra is cranial to the underlying instrumented vertebra, caudal to the underlying unfused vertebra, or the adjacent unfused vertebra include a first unfused vertebra located cranial to the underlying instrumented vertebra and a second unfused vertebra located caudal to the underlying unfused vertebra.

8. The fusion system of any one of the preceding claims, wherein the tension component (106) is coupleable to the underlying vertebra via coupling to the fusion implant (102).

9. The fusion system of any one of the preceding claims, wherein the tension component (106) includes an elongate polyester band.

10. The fusion system of any one of the preceding claims, wherein the selected value of tension is applied to the tension component (106) to attenuate proximal junction or distal junction kyphosis of adjacent unfused vertebra.