Biomechanics of Prophylactic Tethering for Proximal Junctional Kyphosis: Characterization of Spinous Process Tether Pretensioning and Pull-Out Force

Mar, Damon E.; Clary, Steven J.; Burton, Douglas C.; McIff, Terence E.

doi:10.1016/j.jspd.2018.06.017

Cited by 14 publications

(13 citation statements)

References 28 publications

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“…While the ACL is certainly one of the most significant and well described ligaments, many other ligaments are critical to joint stability throughout the human body. Moreover, surgery for ligament reconstruction is common and standard of care in hand surgery, foot and ankle surgery, orthopedic trauma surgery and even spine surgery [ 58 , 59 , 60 ]. In general, ligaments of joints smaller than the knee are reconstructed using Ethicon, fibre wire, Ethibond sutures or mersilene tape.…”

Section: Discussionmentioning

confidence: 99%

Investigating Commercial Filaments for 3D Printing of Stiff and Elastic Constructs with Ligament-Like Mechanics

et al. 2020

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The current gold standard technique for treatment of anterior cruciate ligament (ACL) injury is reconstruction with autograft. These treatments have a relatively high failure and re-tear rate. To overcome this, tissue engineering and additive manufacturing are being used to explore the potential of 3D scaffolds as autograft substitutes. However, mechanically optimal polymers for this have yet to be identified. Here, we use 3D printing technology and various materials with the aim of fabricating constructs better matching the mechanical properties of the native ACL. A fused deposition modeling (FDM) 3D printer was used to microfabricate dog bone-shaped specimens from six different polymers—PLA, PETG, Lay FOMM 60, NinjaFlex, NinjaFlex-SemiFlex, and FlexiFil—at three different raster angles. The tensile mechanical properties of these polymers were determined from stress–strain curves. Our results indicate that no single material came close enough to successfully match reported mechanical properties of the native ACL. However, PLA and PETG had similar ultimate tensile strengths. Lay FOMM 60 displayed a percentage strain at failure similar to reported values for native ACL. Furthermore, raster angle had a significant impact on some mechanical properties for all of the materials except for FlexiFil. We therefore conclude that while none of these materials alone is optimal for mimicking ACL mechanical properties, there may be potential for creating a 3D-printed composite constructs to match ACL mechanical properties. Further investigations involving co-printing of stiff and elastomeric materials must be explored.

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Section: Discussionmentioning

confidence: 99%

Investigating Commercial Filaments for 3D Printing of Stiff and Elastic Constructs with Ligament-Like Mechanics

et al. 2020

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“…Suture loops and tethers have been shown to significantly reduce the flexion and/or extension ROM. However, these effects appear only to be biomechanically relevant if sufficient pretension is applied while the effect-size was also shown to depend on the amount of pretension [27,29,30,32]. Overall, reduced flexion-extension ROMs were accompanied with decreased IDPs, indicating reduced transfer of stresses to the vertebral bodies, and therefore the possible reduction of both PJK and PJF incidence.…”

Section: Biomechanical Evidencementioning

confidence: 94%

“…Two studies investigating hand tied (non-tensioned) suture loops, did not find any significant effect of suture loops on the ROM at index level [27,28]. Mar et al (2019a) investigated the effect of different pretension levels (0, 22, 44, 66, 88N) of suture loops on single human functional spinal units (T11−T12) and measured a reduced flexion ROM as well as decreased IDPs with increasing suture loop pretension [30]. In another study by the same authors, these suture loops were pretensioned to 22N [29].…”

Section: Suture Loops and Tethersmentioning

confidence: 99%

Instrumentation techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction—a systematic review of biomechanical studies

et al. 2021

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“…1 Because the stiffness of the construct is implicated in the development of PJK, 27,28 several prophylactic strategies have been discussed. [5][6][7][8][9][10][11] The biomechanical concept of using a semirigid bridge as a transition from a rigid to a flexible nonfused zone was addressed in this study, using PEEK rods attached to the proximal end of the PSR construct with inline connectors.…”

Section: Discussionmentioning

confidence: 99%

“…Previously reported techni ques include hooks, posterior bands or ligament augmentation, or cement augmentation, with variable results. [5][6][7][8][9][10][11] Polyetheretherketone (PEEK) rods have been used as a biomaterial in various configurations for semirigid and dynamic stabilization spinal procedures. 12 PEEK is a thermoplastic, biocompatible, radiolucent polymer that resists chemical and radiation damage and that has less rigidity than metallic rods; thus, it has an elasticity modulus that is closer to cancellous bone.…”

Section: Introductionmentioning

confidence: 99%

Biomechanical Effects of Proximal Polyetheretherketone Rod Extension on the Upper Instrumented and Adjacent Levels in a Human Long-Segment Construct: A Cadaveric Model

Pereira

Lehrman²,

Sawa³

et al. 2022

Neurospine

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Objective: The high mechanical stress zone at the sudden transition from a rigid to flexible region is involved in proximal junctional kyphosis (PJK) physiopathology. We evaluated the biomechanical performance of polyetheretherketone (PEEK) rods used as a nontraditional long semirigid transition phase from a long-segment metallic rod construct to the nonfused thoracic spine.Methods: Pure moment range of motion (ROM) tests (7.5 Nm) were performed on 7 cadaveric spine segments followed by compression (200 N). Specimens were tested in the following conditions: (1) intact; (2) T10-pelvis pedicle screws and rods (PSRs); and (3) extending the proximal construct to T6 using PEEK rods (PSR+PEEK). T10–11 rod strain, T9 anterolateral bone strain, and T10 screw bending moments were analyzed.Results: At the upper instrumented vertebra (UIV)+1, PSR+PEEK versus PSR significantly decreased ROM in flexion (115%, p = 0.02), extension (104%, p = 0.003), left lateral bending (46%, p = 0.02), and right lateral bending (63%, p = 0.008). Also, at UIV+1, PSR+PEEK versus intact significantly decreased ROM in flexion (111%, p = 0.01) and extension (105%, p = 0.003). The UIV+1 anterior column bone strain was significantly reduced with PSR+PEEK versus PSR during right lateral bending (p = 0.02). Rod strain polarities reversed with PEEK rods in all loading directions except compression.Conclusion: Extending a long-segment construct using PEEK rods caused a decrease in adjacent-level hypermobility as a consequence of long-segment immobilization and also redistributed the strain on the UIV and adjacent levels, which might contribute to PJK physiopathology. Further studies are necessary to observe the clinical outcomes of this technique.

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Biomechanics of Prophylactic Tethering for Proximal Junctional Kyphosis: Characterization of Spinous Process Tether Pretensioning and Pull-Out Force

Cited by 14 publications

References 28 publications

Investigating Commercial Filaments for 3D Printing of Stiff and Elastic Constructs with Ligament-Like Mechanics

Investigating Commercial Filaments for 3D Printing of Stiff and Elastic Constructs with Ligament-Like Mechanics

Instrumentation techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction—a systematic review of biomechanical studies

Biomechanical Effects of Proximal Polyetheretherketone Rod Extension on the Upper Instrumented and Adjacent Levels in a Human Long-Segment Construct: A Cadaveric Model

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