Dynamic Neutralization of the Lumbar Spine After Microsurgical Decompression in Acquired Lumbar Spinal Stenosis and Segmental Instability

Würgler-Hauri, Carola C.; Kalbarczyk, Andreas; Wiesli, Markus; Landolt, Hans; Fandiño, Javier

doi:10.1097/brs.0b013e31816245c0

Cited by 88 publications

(72 citation statements)

References 29 publications

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“…Although FCF was noticeably increased at the adjacent levels, it remains much lower than the values of the fusion model (?169% under extension; ?28.9% under torsion) [20]. At present, several clinical reports have demonstrated that Dynesys implantation does not induce a problem in the adjacent facet joint [2][3][4][5][6][7]. Therefore, the present study deems that Dynesys resulted in a lower incidence of adjacent facet degeneration than did the rigid fixation system.…”

Section: Discussionmentioning

confidence: 47%

“…The location of high screw stress in FE analysis was different from the location of screw breakage in a previous clinical report [7]. One possible reason may be the modelling of the bone-screw interface and consideration of the screw thread.…”

Section: Discussionmentioning

confidence: 67%

“…Several clinical reports also noted the complication of a broken screw [4,6,7]. The location of high screw stress in FE analysis was different from the location of screw breakage in a previous clinical report [7].…”

Section: Discussionmentioning

confidence: 85%

“…In addition, although a higher cord pretension can slightly reduce the FCF of the adjacent levels, it only had a minor influence on the adjacent facet joint due to the considerably lower FCF when compared with the fusion case. Some clinical studies have reported that a disc degeneration of between 7.5 and 47% was noticed at the adjacent level after implantation of the Dynesys system [4][5][6][7]. The long-term complications of ASD may be explained by a prominently increased disc annulus stress of the adjacent levels under flexion and lateral bending following the implantation of Dynesys when using a 300-N cord pretension.…”

Section: Discussionmentioning

confidence: 99%

“…The PET cord resists tensile forces to limit flexion, and the PCU spacer sustains compressive forces to prevent excessive extension. Clinical reports have indicated that Dynesys provides a safe and effective alternative in the treatment of unstable lumbar diseases, with a reported satisfaction rate ranging from 60 to 90% [3][4][5][6][7]. However, complications including ASD, screw loosening, and screw breakage have occurred in the postoperative period [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Effect of the cord pretension of the Dynesys dynamic stabilisation system on the biomechanics of the lumbar spine: a finite element analysis

Liu

Zhong²,

Hsu³

et al. 2011

Eur Spine J

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The Dynesys dynamics stabilisation system was developed to maintain the mobility of motion segment of the lumbar spine in order to reduce the incidence of negative effects at the adjacent segments. However, the magnitude of cord pretension may change the stiffness of the Dynesys system and result in a diverse clinical outcome, and the effects of Dynesys cord pretension remain unclear. Displacement-controlled finite element analysis was used to evaluate the biomechanical behaviour of the lumbar spine after insertion of Dynesys with three different cord pretensions. For the implanted level, increasing the cord pretension from 100 to 300 N resulted in an increase in flexion stiffness from 19.0 to 64.5 Nm/deg, a marked increase in facet contact force (FCF) of 35% in extension and 32% in torsion, a 40% increase of the annulus stress in torsion, and an increase in the high-stress region of the pedicle screw in flexion and lateral bending. For the adjacent levels, varying the cord pretension from 100 to 300 N only had a minor influence on range of motion (ROM), FCF, and annulus stress, with changes of 6, 12, and 9%, respectively. This study found that alteration of cord pretension affects the ROM and FCF, and annulus stress within the construct but not the adjacent segment. In addition, use of a 300 N cord pretension causes a much higher stiffness at the implanted level when compared with the intact lumbar spine.

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Section: Discussionmentioning

confidence: 47%

Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of the cord pretension of the Dynesys dynamic stabilisation system on the biomechanics of the lumbar spine: a finite element analysis

Liu

Zhong²,

Hsu³

et al. 2011

Eur Spine J

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Pedicle screw‐based posterior dynamic stabilizers for degenerative spine: In vitro biomechanical testing and clinical outcomes

Chamoli

Diwan

Tsafnat

2013

J Biomedical Materials Res

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Dynamic stabilization in a degenerate symptomatic spine may be advantageous compared with conventional fusion procedures, as it helps preserve motion and minimizes redistribution of loads at instrumented and adjacent segments. This article presents a systematic review of biomechanical and clinical evidence available on some of the pedicle screw based posterior dynamic stabilization (PDS) devices. Using Medline, Embase, and Scopus online databases, we identified four pedicle-screw-PDS devices for which both, biomechanical testing and clinical follow-up data are available: Graf artificial ligaments, Isobar TTL, Polyetheretherketone rods, and Dynesys. The current state-of-the-art of pedicle-screw-PDS devices is far from achieving its desired biomechanical efficacy, which has resulted in a weak support for the posited clinical benefits. Although pedicle-screw-PDS devices are useful in salvaging a moderately degenerate functionally suboptimal disc, for severe disc degeneration cases fusion is still the preferred choice. We conclude that a pedicle-screw-PDS device should aim at restoring load sharing amongst spinal elements while preserving the qualitative and quantitative nature of spinal motion, especially minimize posterior shift of the helical axis of motion. More precise and objective assessment techniques need to be standardized for in vivo evaluation of intervertebral motion and load sharing amongst spinal elements across different pedicle-screw-PDS devices.

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Lessons Learned from Positive Biomechanics and Poor Clinical Outcomes

Erbulut

Matsumoto

Shah

et al. 2020

Handbook of Spine Technology

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Dynamic Neutralization of the Lumbar Spine After Microsurgical Decompression in Acquired Lumbar Spinal Stenosis and Segmental Instability

Abstract: The reported biomechanical principles of Dynesys do not reflect advantages in outcome compared with none or others stabilization systems after microsurgical radicular decompression reported in the literature.

Cited by 88 publications

References 29 publications

Effect of the cord pretension of the Dynesys dynamic stabilisation system on the biomechanics of the lumbar spine: a finite element analysis

Effect of the cord pretension of the Dynesys dynamic stabilisation system on the biomechanics of the lumbar spine: a finite element analysis

Pedicle screw‐based posterior dynamic stabilizers for degenerative spine: In vitro biomechanical testing and clinical outcomes

Lessons Learned from Positive Biomechanics and Poor Clinical Outcomes

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