Intervertebral disc changes with angulation, compression and reduced mobility simulating altered mechanical environment in scoliosis

Stokes, Ian A. F.; McBride, Carole; Aronsson, David D.; Roughley, Peter J.

doi:10.1007/s00586-011-1868-5

Cited by 19 publications

(16 citation statements)

References 32 publications

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“…Manual tracing is a relatively common method used to determine fiber orientation in soft collagenous tissues [33][34][35], and permits comparing with a reference set by an expert. We conducted three test cases: loaded tendon fibers, a single curved silk fiber, and a sample of cornea from an eye at high intraocular pressure.…”

Section: Accuracy In Tendon Single Fibers and Corneamentioning

confidence: 99%

Polarization microscopy for characterizing fiber orientation of ocular tissues

Jan

Grimm

Tran

et al. 2015

Biomed. Opt. Express

150

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Characterizing the collagen fiber orientation and organization in the eye is necessary for a complete understanding of ocular biomechanics. In this study, we assess the performance of polarized light microscopy to determine collagen fiber orientation of ocular tissues. Our results demonstrate that the method provides objective, accurate, repeatable and robust data on fiber orientation with µm-scale resolution over a broad, cmscale, field of view, unaffected by formalin fixation, without requiring tissue dehydration, labeling or staining. Together, this shows that polarized light microscopy is a powerful method for studying collagen architecture in the eye, with applications ranging from normal physiology and aging, to pathology and transplantation.

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Section: Accuracy In Tendon Single Fibers and Corneamentioning

confidence: 99%

Polarization microscopy for characterizing fiber orientation of ocular tissues

Jan

Grimm

Tran

et al. 2015

Biomed. Opt. Express

150

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show abstract

“…The mechanism by which the discs become wedged is poorly understood. Endplate calcification has been observed in discs of humans with scoliosis and in a porcine model of induced scoliosis, and is considered as a possible cause of nutritional compromise and consequent disc degeneration and wedging in scoliosis [30–32]. But we did not do examinations on endplate calcification for patients with AIS routinely.…”

Section: Discussionmentioning

confidence: 99%

“…But we did not do examinations on endplate calcification for patients with AIS routinely. Stokes et al [32] reported that reduced mobility was a major source of disc changes and may be a factor in disc deformity. In the previous literature, posterior procedure fused more motion segments and reduced more mobility compared with anterior procedure.…”

Section: Discussionmentioning

confidence: 99%

Radiographic evaluation of posterior selective thoracolumbar or lumbar fusion for moderate Lenke 5C curves

Zhang

Lin

Zhang

et al. 2016

Arch Orthop Trauma Surg

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IntroductionPosterior selective thoracolumbar or lumbar (TL/L) fusion with pedicle screw constructs for adolescent idiopathic scoliosis (AIS) has been studied in a few researches. However, few studies have discussed the indication for selective TL/L fusion and the behaviors of its adjacent disc angle. The present study aims to discuss the indication for posterior selective TL/L fusion and the behavior of the adjacent disc angle.Methods45 consecutive cases of AIS undergoing posterior selective TL/L fusion were retrospectively evaluated, with an average follow-up of 36 months. Radiographs were reviewed to determine the coronal curve magnitude and the sagittal alignment preoperatively, postoperatively and at final follow-up. Thoracic curves in groups A had a correction loss of more than 5°, while thoracic curves in group B had a correction loss of not more than 5°.ResultsThe coronal curve magnitude of the TL/L curve averaged 44° preoperatively and it was corrected to 6° immediately with a correction rate of 84.8 %. At final follow-up it was 9° with a correction loss of 3°. The minor thoracic curve was 26° preoperatively, and the convex side bending curve magnitude averaged 8° with a flexibility of 72.7 %. It was corrected to 13° immediately with a spontaneous correction of 48.5 %. At final follow-up it was 14° with a correction loss of 1°. UIVA decreased from 4° to 2° after surgery, and it was 2° at final follow-up. LIVA decreased from 7° to 4° after surgery, and it was 5° at final follow-up. Maximal correction of TL/L curves in group A is significantly less than that in group B. 1 patient received revision surgery to fuse the progressive thoracic curve.ConclusionPosterior selective TL/L fusion with pedicle screw constructs allows for spontaneous thoracic correction and maintains coronal and sagittal balance during the follow-up. Maximal correction instead of undercorrection was recommended for moderate Lenke 5C curves. Disc wedging could be improved after surgery and well maintained during the follow-up.

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“…In the absence of a surrogate scoliosis model, we have chosen to use a calf spine model, which, although possessing an anatomy and vertebral kinematics similar to those of a normal human spine, 3,6 cannot simulate the rotational deformation and altered geometry and mechanics of the vertebrae and of the intervertebral discs that are typical of a scoliotic spine. 19,21,30,31 In particular, the wedging of the vertebrae and discs and the reduced mobility exhibited by scoliotic spines will cause significant lateral deformation of the spine and altered intersegmental stiffness throughout the spine, both of which are not accounted for in our model. 21 As demonstrated in the current study, local changes in the boundary conditions and kinematical constraints of the instrumented vertebra will significantly affect the obtained derotation of the vertebrae for a given rotation imparted by the surgeon.…”

Section: Discussionmentioning

confidence: 99%

The effect of screw head design on rod derotation in the correction of thoracolumbar spinal deformity

Lam

Groff

Alkalay

2013

SPI

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Object. The use of fixed-axis pedicle screws for correction of thoracolumbar deformity in adult surgery is demanding because of the challenge of assembling the bent rod to the screw in order to achieve curve correction. Polyaxial screw designs, providing increased degrees of freedom at the screw-rod interface, were reported to be insufficient in achieving correction of thoracic deformity in the axial plane. Using a multisegment bovine calf spine model, this study investigated the ability of a new uniplanar screw design to achieve derotation correction of the vertebrae and maintain a degree of correction comparable to that of fixed-axis and polyaxial screw designs.Methods. Eighteen calf thoracolumbar spine segments from T-6 to L-1 (n = 6 per screw design) underwent bilateral facetectomies at the T9-11 levels and were instrumented bilaterally with pedicle screws and rods. To assess the efficacy of each screw design in imparting rotational correction, each instrumented level was tested under applied torsional moments designed to simulate the motion applied during derotation surgery. Once rotation was achieved, the whole spine was tested to assess the overall stiffness of the construct.Results. The fixed-axis construct showed increased efficacy in imparting rotation compared with the uniplanar (115% increase, p > 0.05) and polyaxial (210% increase, p < 0.05) constructs. Uniplanar screws showed a 21% increase in torsional stiffness compared with the polyaxial screws, but this difference was not statistically significant.Conclusions. The design of screw heads plays a significant role in affecting the rotation of the vertebrae during the derotation procedure. Uniplanar screws may have the advantage of maintaining construct stiffness after derotation.

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Intervertebral disc changes with angulation, compression and reduced mobility simulating altered mechanical environment in scoliosis

Cited by 19 publications

References 32 publications

Polarization microscopy for characterizing fiber orientation of ocular tissues

Polarization microscopy for characterizing fiber orientation of ocular tissues

Radiographic evaluation of posterior selective thoracolumbar or lumbar fusion for moderate Lenke 5C curves

The effect of screw head design on rod derotation in the correction of thoracolumbar spinal deformity

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