Spinal Growth Modulation With an Anterolateral Flexible Tether in an Immature Bovine Model

Newton, Peter O.; Farnsworth, Christine L.; Faro, Frances D.; Mahar, Andrew; Odell, Tim; Mohamad, Fazir; Breisch, Eric; Fricka, Kevin B.; Upasani, Vidyadhar V.; Amiel, David

doi:10.1097/brs.0b013e31816950a0

Cited by 107 publications

(64 citation statements)

References 33 publications

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“…Such apprehension is supported by the observation of irregular stress profiles within the growth plates-a phenomenon believed to promote disc degeneration. Implicated researchers have explored this issue and found various stress-induced or hypomobility-related changes in the discs of instrumented segments [10,21]. In an attempt to address this concern, a fusionless growth-sparing ministaple has subsequently been developed that does not alter the mechanical environment of the intervertebral discs [26].…”

Section: Discussionmentioning

confidence: 98%

Biomechanical comparison of fusionless growth modulation corrective techniques in pediatric scoliosis

Driscoll

Aubin

Moreau

et al. 2011

Med Biol Eng Comput

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Fusionless growth-sparing implants for the treatment of adolescent idiopathic scoliosis (AIS) attempt to manipulate vertebral growth to restore spinal alignment. This study critically explores different implants utilizing a human spine scoliotic finite element model (FEM). Stainless steel (SS) and shape memory alloy (SMA) staples and flexible tethers were modeled and alternatively integrated around the apex of the convexity of the scoliotic model. Stress profiles over vertebral growth plates were obtained. Two years of growth was simulated with non-instrumented and instrumented models, as curvature changes were quantified. Apical asymmetrical stresses in non-instrumented and instrumented scoliotic models with SS staple, flexible tether, and SMA staple were 0.48, 0.48, 0.23, and 0.33 MPa, respectively. Patient data and non-instrumented model progressed from 28° to 62° of thoracic Cobb angle over 2 years. Simulated projected long-term thoracic Cobb angles of instrumented models are 31° with SS staple, 31° with flexible tether, and 34° with SMA staple. Initial implant compression achieved during instrumentation provided a significant influence on initial and long-term spinal profiles. The developed FEM provides an effective platform with which to explore, critique, and enhance fusionless growth-sparing techniques.

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Section: Discussionmentioning

confidence: 98%

Biomechanical comparison of fusionless growth modulation corrective techniques in pediatric scoliosis

Driscoll

Aubin

Moreau

et al. 2011

Med Biol Eng Comput

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“…Non-fusion correction of AIS has many potential advantages over current surgical strategies [6][7][8][9][10][11][12]. Using the natural growth of the spine to favorably realign, the scoliotic deformity may permit preservation of spinal growth and mobility.…”

Section: Introductionmentioning

confidence: 99%

The impact of a corrective tether on a scoliosis porcine model: a detailed 3D analysis with a 20 weeks follow-up

et al. 2013

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Purpose Non-fusion treatment for adolescent idiopathic scoliosis generates interest due to the potential for growth preservation and mobility. Using an established porcine scoliotic model, this study aims to evaluate the global alignment and the morphology of the spine with and without application of a non-fusion corrective tether. Methods At 12 weeks of age, 21 immature Yorkshire pigs had an induction of scoliosis. Once a 50°Cobb angle was obtained; animals were placed into one of the following groups: a scoliosis model group (SM, n = 11) where animals were euthanized, tether release group (TR, n = 5) where the inducing tether was removed, and an anterior correction group (AC, n = 5) where the inducing tether was removed and non-fusion corrective tether was applied. TR and AC were observed for a further 20 weeks and then euthanized. Post-mortem CT scans were used to create 3D spinal reconstructions to obtain global and morphologic parameters. Results Maximal Cobb angle of the scoliotic deformity was significantly lower for AC (27.9°± 12.0°) than for the two other groups (TR 52.7°± 10.0°, SM 48.3°± 7.6°). AC experienced an increase in kyphosis (24.2°± 15.9°) compared to TR (7.1°± 6.4°). Correction in the axial plane was also observed in AC versus TR. Correction of vertebral wedging was found for AC compared to SM and TR in the three apical vertebrae.Conclusions 3D realignment of scoliotic curves was observed with application of the corrective tether. The correction was the product of both mechanical action and growth modulation. These findings are encouraging for future development of a non-fusion device for the treatment of immature scoliotic curves.

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“…Newer developments have included spinal tethering devices [4,5,11,12], vertebral body staples [3], and epiphyseal systems [14]. Theoretically, an implantable internal bracing system could redirect growth to correct a scoliotic deformity.…”

Section: Introductionmentioning

confidence: 99%

Does Removing the Spinal Tether in a Porcine Scoliosis Model Result in Persistent Deformity?: A Pilot Study

Patel

Schwab

Lafage

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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Background Using a tethering technique, a porcine model of scoliosis has been created. Ideally, tether release before placement and evaluation of corrective therapies would lead to persistent scoliosis. Questions/purposes Does release of the spinal tether result in persistent deformity? Methods Using a unilateral spinal tether and ipsilateral rib cage tethering, scoliosis was initiated on seven pigs. The spinal tether was released after progression to a Cobb angle of 50°. Biweekly radiographs were taken for 18 weeks after tether release to evaluate longitudinal changes in coronal and sagittal Cobb angles. Postmortem fine-cut CT scans were used to evaluate vertebral and disc wedging and axial rotation; results were compared to a previously published data set of 11 animals euthanized before release of the tether (control group). Results Radiographic analysis demonstrated two responses to tether release: a persistent deformity group and an autocorrective group. Differences between these two groups included number of days with the tether in place before reaching a Cobb angle of 50°and degree of deformity immediately after scoliosis induction. CT analysis of the tether release versus tether intact groups demonstrated progression in vertebral body wedging without differences in apical rotation. Conclusions With the appropriate inducing parameters, release of the spinal tether does not systematically result in deformity correction. Tether release resulted in a reduction in Cobb angle in the first several weeks followed by steady curve progression. Deformity progression was confirmed using detailed CT morphometric analysis. Clinical Relevance The tether release model will be used to evaluate corrective nonfusion technologies in future investigations.

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Spinal Growth Modulation With an Anterolateral Flexible Tether in an Immature Bovine Model

Cited by 107 publications

References 33 publications

Biomechanical comparison of fusionless growth modulation corrective techniques in pediatric scoliosis

Biomechanical comparison of fusionless growth modulation corrective techniques in pediatric scoliosis

The impact of a corrective tether on a scoliosis porcine model: a detailed 3D analysis with a 20 weeks follow-up

Does Removing the Spinal Tether in a Porcine Scoliosis Model Result in Persistent Deformity?: A Pilot Study

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