Would CoCr Rods Provide Better Correctional Forces Than Stainless Steel or Titanium for Rigid Scoliosis Curves?

Serhan, Hassan; Mhatre, Devdatt; Newton, Peter O.; Giorgio, Paul del; Sturm, Peter

doi:10.1097/bsd.0b013e31826a0f19

Cited by 69 publications

(39 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the number of pedicle screws attached to the rod and the distance between pedicle screws also affect the overall rod-screw construct stiffness. 36 This explains our result that higher screw density with a less stiff rod construct could achieve similar TK restoration to less screw density with a stiffer rod construct (Group B vs Group C, Table 4). …”

mentioning

confidence: 54%

“…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%

“…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: 99%

“…1, 36 However, most studies were biomechanically based, and only limited clinical studies have reported the effect of rod stiffness on sagittal correction.…”

mentioning

confidence: 99%

See 4 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

View full text Add to dashboard Cite

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.

show abstract

mentioning

confidence: 54%

Section: Methodsmentioning

confidence: 99%

Section: Operation Techniquementioning

confidence: 99%

mentioning

confidence: 99%

“…1, 36 However, most studies were biomechanically based, and only limited clinical studies have reported the effect of rod stiffness on sagittal correction.…”

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

View full text Add to dashboard Cite

show abstract

Assessment of corrosion in retrieved spine implants

et al. 2017

View full text Add to dashboard Cite

Recently the use of dissimilar metals in spine instrumentation has increased, especially in the case of adult deformities, where rods made from Cobalt Chrome alloys (CoCr) are used with Titanium (Ti) screws. The use of dissimilar metals increases the risk of galvanic corrosion and patients have required revision spine surgery due to severe metallosis that may have been caused by corrosion. We aimed to assess the presence of corrosion in spine implant retrievals from constructs with two types of material combinations: similar (Ti/Ti) and dissimilar (CoCr/Ti). First, we devised a grading score for corrosion of the rod-fixture junctions. Then, we applied this score to a collection of retrieved spine implants. Our proposed corrosion grading score was proven reliable (kappa > 0.7). We found no significant difference in the scores between 4 CoCr and 11 Ti rods (p = 0.0642). There was no indication that time of implantation had an effect on the corrosion score (p = 0.9361). We recommend surgeons avoid using implants designs with dissimilar metals to reduce the risk of corrosion whilst a larger scale study of retrieved spine implants is conducted. Future studies can now use our scoring system for spine implant corrosion. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 632-638, 2018.

show abstract