Postoperative Changes in Spinal Rod Contour in Adolescent Idiopathic Scoliosis

Cidambi, Krishna R.; Glaser, Diana; Bastrom, Tracey P.; Nunn, Thomas; Ono, Takashi; Newton, Peter O.

doi:10.1097/brs.0b013e318252ccbe

Cited by 61 publications

(59 citation statements)

References 26 publications

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“…This finding indicated that concave-side rather than convex-side screw density had an impact on TK restoration. It supports the importance of concave-side implant density on TK restoration reported by Cidambi et al 5 and La Rosa et al 15 A possible explanation could be that the increased friction at the screw-rod interface that occurs with higher screw density would prevent flattening of the contoured rod in the sagittal plane after rod rotation (Fig. 1).…”

supporting

confidence: 69%

“…Theoretically, a larger and stiffer rod would have greater ability for correction in the coronal and sagittal planes, based on biomechanical studies. 5,16,36 However, results from different clinical studies have not been in accordance. For coronal plane correction, insufficient evidence was found to support the hypothesis that better correction would be provided by high rod stiffness.…”

mentioning

confidence: 70%

“…Titanium rods of 5.5 mm and 6.35 mm diameter were defined as low stiffness and high stiffness, respectively, according to the literature. 1,5,36 All cases were divided into 4 groups: Group A, low-stiffness rod with low density of screw placement; Group B, low-stiffness rod with high density of screw placement; Group C, high-stiffness rod with low density of screw placement; Group D, high-stiffness rod with high density of screw placement.…”

Section: Methodsmentioning

confidence: 99%

“…The pre-contoured rod model was made preoperatively as described in the literature. 5,36 After the concave rod was engaged in all anchors, rod rotation instruments were attached to the rod. An assistant pushed down on the convex ribs, and the surgeon rotated the concave rod approximately 90° in the direction that would reduce the rib prominence.…”

Section: Operation Techniquementioning

confidence: 99%

“…2, 28 Cidambi et al 5 found that the shape of the pre-contoured rod is associated with TK preservation; Abul-Kasim et al…”

mentioning

confidence: 99%

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Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

Liu

Li²,

Li³

et al. 2015

SPI

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OBJECT The aim of this study was to evaluate the effects of rod stiffness and implant density on coronal and sagittal plane correction in patients with main thoracic curve adolescent idiopathic scoliosis (AIS). METHODS The authors conducted a retrospective study of 77 consecutive cases involving 56 female and 21 male patients with Lenke Type 1 main thoracic curve AIS who underwent single-stage posterior correction and instrumented spinal fusion with pedicle screw fixation between July 2009 and July 2012. The patients' mean age at surgery was 15.79 ± 3.21 years. All patients had at least 1 year of follow-up. Radiological parameters in the coronal and sagittal planes, including Cobb angle of the major curve, side-bending Cobb angle of the major curve, thoracic kyphosis (TK), correction rates, and screw density, were measured and analyzed. Screw densities (calculated as number of screws per fusion segment × 2) of < 0.60 and ≥ 0.60 were defined as low and high density, respectively. Titanium rods of 5.5 mm and 6.35 mm diameter were defined as low and high stiffness, respectively. Patients were divided into 4 groups based on the type of rod and density of screw placement that had been used: Group A, low-stiffness rod with low density of screw placement; Group B, low-stiffness rod with high density of screw placement; Group C, high-stiffness rod with low density of screw placement; Group D, high-stiffness rod with high density of screw placement. RESULTS The mean coronal correction rate of the major curve, for all 77 patients, was (81.45% ± 7.51%), and no significant difference was found among the 4 groups (p > 0.05). Regarding sagittal plane correction, Group A showed a significant decrease in TK after surgery (p < 0.05), while Group D showed a significant increase (p < 0.05); Group B and C showed no significant postoperative changes in TK (p > 0.05). The TK restoration rate was highest in Group D and lowest in Group A (A, −39.32% ± 7.65%; B, −0.37% ± 8.25%; C, −4.04% ± 6.77%; D, 37.59% ± 8.53%). Screw density on the concave side was significantly higher than that on the convex side in all the groups (p < 0.05). CONCLUSIONS For flexible main thoracic curve AIS, both rods with high stiffness and those with low stiffness combined with high or low screw density could provide effective correction in the coronal plane; rods with high stiffness along with high screw density on the concave side could provide better outcome with respect to sagittal TK restoration.

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supporting

confidence: 69%

mentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Operation Techniquementioning

confidence: 99%

“…2, 28 Cidambi et al 5 found that the shape of the pre-contoured rod is associated with TK preservation; Abul-Kasim et al…”

mentioning

confidence: 99%

See 3 more Smart Citations

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

Liu

Li²,

Li³

et al. 2015

SPI

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Identification of optimized rod shapes to guide anatomical spinal reconstruction for adolescent thoracic idiopathic scoliosis

Kokabu

Kanai

Abe

et al. 2018

Journal Orthopaedic Research

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Adolescent idiopathic scoliosis (AIS), the most common pediatric musculoskeletal disorder, causes a three-dimensional deformity of the spine. Although rod curvature could play an important role in anatomical spinal reconstruction in patients with thoracic AIS, intraoperative contouring of the straight rod induces notches into the rod, leading to decreased fatigue strength. Here, we analyzed pre-bent rod geometries from 46 intraoperative tracings of the rod geometry, which can provide anatomical spinal reconstruction in patients with thoracic AIS. The center point clouds of the rod shapes were extracted and approximated as arcs and straight lines. The difference between the center point clouds were evaluated using the iterative closest point methods. When the rod shapes were divided into six groups based on length followed by hierarchical cluster analysis, 10 representative rod shapes were obtained with a difference value of 5 mm. Thus, we identified optimized rod shapes to guide anatomical spinal reconstruction for thoracic AIS, which will reduce not only the risk of rod breakage but also operation time, leading to decreased patient burden. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

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Material Selection Impact on Intraoperative Spine Manipulation and Post-op Correction Maintenance

Zakaria¹,

Marca²

2019

Handbook of Spine Technology

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Postoperative Changes in Spinal Rod Contour in Adolescent Idiopathic Scoliosis

Cited by 61 publications

References 26 publications

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration

Identification of optimized rod shapes to guide anatomical spinal reconstruction for adolescent thoracic idiopathic scoliosis

Material Selection Impact on Intraoperative Spine Manipulation and Post-op Correction Maintenance

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