Mechanical behavior of a novel non-fusion scoliosis correction device

Wessels, Martijn; Hekman, Edsko E.G.; Verkerke, Gijsbertus Jacob

doi:10.1016/j.jmbbm.2013.07.006

Cited by 5 publications

(8 citation statements)

References 18 publications

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“…The U-loops have been designed such that with spinal growth, the anchors slide from the flexible arms of the U-loop to the stiffer semicircular part at the end. This counteracts the decrease in torsion in the springs that occurs with apical rotation during follow-up, resulting in torque that remains relatively constant over time [20]. The torsional device allows 5.0 cm of growth, 2.5 cm on both the cranial and caudal side.…”

Section: Devicesmentioning

confidence: 98%

Induction of a representative idiopathic-like scoliosis in a porcine model using a multidirectional dynamic spring-based system

et al. 2021

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BACKGROUND CONTEXT: Scoliosis is a 3D deformity of the spine in which vertebral rotation plays an important role. However, no treatment strategy currently exists that primarily applies a continuous rotational moment over a long period of time to the spine, while preserving its mobility. We developed a dynamic, torsional device that can be inserted with standard posterior instrumentation. The feasibility of this implant to rotate the spine and preserve motion was tested in growing mini-pigs. PURPOSE: To test the quality and feasibility of the torsional device to induce the typical axial rotation of scoliosis while maintaining growth and mobility of the spine. STUDY DESIGN: Preclinical animal study with 14 male, 7 month old Gottingen mini-pigs. Comparison of two scoliosis induction methods, with and without the torsional device, with respect to 3D deformity and maintenance of the scoliosis after removal of the implants. METHODS: Fourteen mini-pigs received either a unilateral tether-only (n=6) or a tether combined with a contralateral torsional device (n=8). X-rays and CT-scans were made post-operative, at 8 weeks and at 12 weeks. Flexibility of the spine was assessed at 12 weeks. In 3 mini-pigs per condition, the implants were removed and the animals were followed until no further correction was expected. RESULTS: At 12 weeks the tether-only group yielded a coronal Cobb angle of 16.8 §3.3˚For the tether combined with the torsional device this was 22.0 §4.0˚. The most prominent difference at 12 weeks was the axial rotation with 3.6 §2.8˚for the tether-only group compared to 18.1 §4.6˚for the tether-torsion group. Spinal growth and flexibility remained normal and comparable for both groups. After removal of the devices, the induced scoliosis reduced by 41% in both groups. There were no adverse tissue reactions, implant complications or infections. CONCLUSION: The present study indicates the ability of the torsional device combined with a tether to induce a flexible idiopathic-like scoliosis in mini-pigs. The torsional device was necessary to induce the typical axial rotation found in human scoliosis.

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Section: Devicesmentioning

confidence: 98%

Induction of a representative idiopathic-like scoliosis in a porcine model using a multidirectional dynamic spring-based system

et al. 2021

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“…2a). The system is implanted in cold condition, after which the bending moment is gradually applied as the implant warms up to the body temperature (2.8 Nm bending moment [17]). The torsion device, XSTOR, was manufactured from titanium grade 23 and consists of two torsion springs, two U-loops, and sliding anchors similar to the XSLAT (Fig.…”

Section: Devicesmentioning

confidence: 99%

“…2b). The torsion springs were preloaded (with 1 Nm torque each [17]) before fixation to the apical vertebra. For both devices, the sliding anchors are connected to the vertebrae by a transverse connector between a pair of pedicle screws (Fig.…”

Section: Devicesmentioning

confidence: 99%

“…We developed a novel posterior non-fusion scoliosis correction system, referred to as the XSLATOR [17,18]. This system applies continuous coronal and axial corrective forces.…”

Section: Introductionmentioning

confidence: 99%

“…The other (XSTOR; eXtendable implant correcting Scoliosis in TORsion) is a torsion-generating element that uses spinal growth for post-operative correction. Due to the flexibility of both elements, the additional stiffness to the spine is in the order of 10 % [17], which allows physiological motion. The important advantages of this are a much lower likelihood of spontaneous fusion and lower stresses on the proximal and distal anchors.…”

Section: Introductionmentioning

confidence: 99%

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Spinal shape modulation in a porcine model by a highly flexible and extendable non-fusion implant system

et al. 2016

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Purpose In vivo evaluation of scoliosis treatment using a novel approach in which two posterior implants are implanted: XSLAT (eXtendable implant correcting Scoliosis in LAT bending) and XSTOR (eXtendable implant correcting Scoliosis in TORsion). The highly flexible and extendable implants use only small, but continuous lateral forces (XSLAT) and torques (XSTOR), thereby allowing growth and preventing fusion. Methods Since (idiopathic) scoliosis does not occur spontaneously in animals, the device was used to induce a spinal deformity rather than correct it. Six of each implants were tested for their ability to induce scoliotic deformations in 12 growing pigs. Each implant spanned six segments and was attached to three vertebrae using sliding anchors. Radiological and histological assessments were done throughout the 8-week study. Results In all animals, the intended deformation was accomplished. Average Cobb angles were 19°for XSLAT and 6°for XSTOR. Average apical spinal torsion was 0°f or XSLAT and 9°for XSTOR. All instrumented segments remained mobile and showed 20 % growth. Moderate degeneration of the facet joints was observed and some debris was found in the surrounding tissue.Conclusions The approach accomplished the intended spinal deformation while allowing growth and preventing fusion.

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Mechanical testing of the thoracic spine and related implants

Mannen

Anderson

2017

Mechanical Testing of Orthopaedic Implants

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Mechanical behavior of a novel non-fusion scoliosis correction device

Cited by 5 publications

References 18 publications

Induction of a representative idiopathic-like scoliosis in a porcine model using a multidirectional dynamic spring-based system

Induction of a representative idiopathic-like scoliosis in a porcine model using a multidirectional dynamic spring-based system

Spinal shape modulation in a porcine model by a highly flexible and extendable non-fusion implant system

Mechanical testing of the thoracic spine and related implants

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