Thermomechanical Effects of Spine Surgery Rods Composed of Different Metals and Alloys

Noshchenko, Andriy; Patel, Vikas V.; Baldini, Todd; Yun, Lu; Lindley, Emily M.; Burger, Evalina L.

doi:10.1097/brs.0b013e3181e6ce16

Cited by 10 publications

(6 citation statements)

References 12 publications

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“…Unfortunately we did not have the opportunity to study the influence of all of these factors on springback in this study. However, previous publications have demonstrated that autoclaving significantly modifies thermo‐mechanical effects in medical rods manufactured from different metals and alloys 20, 21. Autoclaving is a routine procedure used in surgical practice for medical rods sterilization.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of spinal instrumentation rod bending characteristics for in‐situ contouring

et al. 2011

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Bending characteristics were studied in rods used for spinal instrumentation at in-situ contouring conditions. Five groups of five 6 mm diameter rods made from: cobalt alloy (VITALLIUM), titanium-aluminum-vanadium alloy (SDI™), β-titanium alloy (TNTZ), cold worked stainless steel (STIFF), and annealed stainless steel (MALLEABLE) were studied. The bending procedure was similar to that typically applied for in-situ contouring in the operating room and included two bending cycles: first--bending to 21-24° under load with further release of loading for 10 min, and second--bending to 34-37° at the previously bent site and release of load for 10 min. Applied load, bending stiffness, and springback effect were studied. Statistical evaluation included ANOVA, correlation and regression analysis. TNTZ and SDI™ rods showed the highest (p < 0.05) springback at both bending cycles. VITALLIUM and STIFF rods showed mild springback (p < 0.05). The least (p < 0.05) springback was observed in the MALLEABLE rods. Springback significantly correlated with the bend angle under load (p < 0.001). To reach the necessary bend angle after unloading, over bending should be 37-40% of the required angle in TNTZ and SDI™ rods, 27-30% in VITALLIUM and STIFF rods, and around 20% in MALLEABLE rods.

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Section: Discussionmentioning

confidence: 99%

Evaluation of spinal instrumentation rod bending characteristics for in‐situ contouring

et al. 2011

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“…The clinical relevance of shape loss was suggested by Noshchenko et al 7 to be detrimental to the spine fusion constructs, even though it was relatively small. 7 This is of concern because previous literature has also suggested that CPTi rods are prone to shape loss after autoclaving and manual bending. 6 This was reproduced in our study because all CPTi rods (in addition to all CoCr rods) demonstrated statistically significant loss of shape over time.…”

Section: Discussionmentioning

confidence: 99%

“…Similar to prior studies, the rate of shape loss was highest during the first 2 days of the study and then decreased to a rate approaching zero by 8 weeks. 6,7 This early shape loss is likely a result of elastic recoil. That is, the amount of deformation created was not enough to surpass the yield point.…”

Section: Discussionmentioning

confidence: 99%

“…5 Although titanium has many benefits because of its aforementioned properties, recent studies have shown that it is more prone to shape loss after contouring when compared with SS. 6,7 This should be of importance to spine surgeons because shape loss of surgical spine rods has been implicated as a possible contributing factor leading to postsurgical loss of sagittal balance and instrumentation failure at the most superior end of the fixation construct. 3,6 Altogether, this has led to further investigation of other metals and alloys that are more resistant to shape loss after bending and, thus, likely more ideal for use as implants in surgery to correct spinal deformity.…”

Section: Introductionmentioning

confidence: 99%

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Shape Loss of Autoclaved, Machine-Bent Cobalt-Chrome and Titanium Spine Surgery Rods

Willson

Zhou

Fulzele

et al. 2020

Global Spine Journal

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Study Design: This was a biomechanical study. Objective: Shape loss of surgical spine rods has been implicated as a factor leading to postsurgical loss of alignment correction. Our objective was to compare the degree of shape loss in surgical spine rods of different compositions under physiological conditions that were bent before or after being autoclaved.Methods: 10 CoCr and 10 commercially pure titanium (CPTi) surgical spine rods were contoured using a machine press. Five CoCr and 5 CPTi rods were bent before being autoclaved (preoperative bent group); 5 CoCr and 5 CPTi rods were bent after being autoclaved (intraoperative bent group). All rods were immersed in a phosphate-buffered saline bath at body temperature (37.2 C + 2 C). Changes in radius of curvature were measured at different time intervals over an 8-week course using a highdefinition scanner.Results: Each rod demonstrated shape loss in radius of curvature (range ¼ 1.04-9.99 mm) over the duration of the study. Intraoperatively bent CPTi rods demonstrated the largest shape loss (range ¼ 8.73-9.99 mm; median 9.33 mm; P < .01). Preoperatively bent CPTi (range ¼ 1.04-1.71 mm; median ¼ 1.39 mm; P < .01) and intraoperatively bent CoCr (range ¼ 1.11-2.11 mm; median ¼ 2.01 mm; P < .01) rods underwent the least amount of shape loss.Conclusion: CPTi spinal rods bent after autoclave may lead to considerable loss of alignment correction. In addition, our results suggest that preautoclave bent CPTi and CoCr spinal rods bent after autoclave may be a more ideal choice of implant because they may provide more resistance to shape loss over time.

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“…Ti-6Al-4V is stronger and stiffer than Commercially Pure Titanium, readily available, and easily to machine. After contouring, such as in the case of spinal rods, Ti-6Al-4V also holds its shape better over temperature changes than commercially pure titanium (Noshchenko et al 2011). Titanium-molybdenum is more difficult and expensive to obtain, and requires advanced expertise in machining, due to its nature of clogging cutting tools.…”

Section: Metallic Implantsmentioning

confidence: 99%

Mechanical Implant Material Selection, Durability, Strength, and Stiffness

Sommerich¹,

DeCelle²,

Frasier³

2019

Handbook of Spine Technology

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Spinal implants are manufactured from a variety of materials to meet user needs as well as the requirements of the physical and environmental demands upon the device. Commonly used materials include titanium, stainless steel, cobalt-chrome, nitinol, carbon fiber reinforced polymer (CFRP), polyetheretherketone (PEEK), silicon nitride, biodegradable polymers, and allograft bone. Material choices can be driven by requirements for strength, biocompatibility, bone ongrowth, flexibility, and radiolucency. Coatings may also be applied to the implants to further enhance physical or biological properties of the implant. These may include hydroxyapatite, titanium plasma, or a combination of

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Thermomechanical Effects of Spine Surgery Rods Composed of Different Metals and Alloys

Abstract: The shape of the hand contoured CPTi rods was the least stable of the rods across all applied temperature conditions. The SS and Ti-6Al-4V rods were more stable than CPTi rods. Autoclaving before handcontouring tended to increase rods' shape loss.

Cited by 10 publications

References 12 publications

Evaluation of spinal instrumentation rod bending characteristics for in‐situ contouring

Evaluation of spinal instrumentation rod bending characteristics for in‐situ contouring

Shape Loss of Autoclaved, Machine-Bent Cobalt-Chrome and Titanium Spine Surgery Rods

Mechanical Implant Material Selection, Durability, Strength, and Stiffness

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