Bending Fatigue and Spring Back Properties of Implant Rods Made of β-Type Titanium Alloy for Spinal Fixture

Narita, Kouji; Niinomi, Mitsuo; Nakai, Masaaki; Akahori, Toshikazu; Tsutsumi, Harumi; Oribe, Kazuya

doi:10.4028/www.scientific.net/amr.89-91.400

Cited by 7 publications

(1 citation statement)

References 6 publications

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“…The springback, which is a property that makes the material return to its original shape, is affected by the material properties (yield strength, modulus of elasticity) and thickness, machining angle, and bending radius [20][21][22]. Therefore, the CAM data were established considering the springback phenomenon of materials to perform accurate bending.…”

Section: • Computer-aided Manufacturing (Cam) Data and Fabrication Ofmentioning

confidence: 99%

Computer-Aided Design and Manufacturing Technology for Identification of Optimal Nuss Procedure and Fabrication of Patient-Specific Nuss Bar for Minimally Invasive Surgery of Pectus Excavatum

Kim¹,

Heo²,

Hoseok

et al. 2018

Applied Sciences

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The Nuss procedure is one of the most widely used operation techniques for pectus excavatum (PE) patients. It attains the normal shape of the chest wall by lifting the patient’s chest wall with the Nuss bar. However, the Nuss bar is for the most part bent by a hand bender according to the patient’s chest wall, and this procedure causes various problems such as the failure of the operation and a decreased satisfaction of the surgeon and patient about the operation. To solve this problem, we proposed a method for deriving the optimal operation result by designing patient-specific Nuss bars through computer-aided design (CAD) and computer-aided manufacturing (CAM), and by performing auto bending based on the design. In other words, a three-dimensional chest wall model was generated using the computed tomography (CT) image of a pectus excavatum patient, and an operation scenario was selected considering the Nuss bar insertion point and the post-operative chest wall shape. Then, a design drawing of the Nuss bar that could produce the optimal operation result was derived from the operation scenario. Furthermore, after a computerized numerical control (CNC) bending machine for the Nuss bar bending was constructed, the Nuss bar prototype was manufactured based on the derived design drawing of the Nuss bar. The Nuss bar designed and manufactured with the proposed method has been found to improve the Haller index (HI) of the pectus excavatum patient by approximately 37% (3.14 before to 1.98 after operation). Moreover, the machining error in the manufacturing was within ±5% compared to the design drawing. The method proposed and verified in this study is expected to reduce the failure rate of the Nuss procedure and significantly improve the satisfaction of the surgeon and patient about the operation.

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Section: • Computer-aided Manufacturing (Cam) Data and Fabrication Ofmentioning

confidence: 99%

Computer-Aided Design and Manufacturing Technology for Identification of Optimal Nuss Procedure and Fabrication of Patient-Specific Nuss Bar for Minimally Invasive Surgery of Pectus Excavatum

Kim¹,

Heo²,

Hoseok

et al. 2018

Applied Sciences

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Introduction

2017

Metallic Biomaterials

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Spine rod straightening as a possible cause for revision

Ayers

Hayne

Burger

2017

J Mater Sci: Mater Med

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In a previous study, the authors examined the elastic and short-term anelastic springback of Ti6Al4V, CoCrMoC and A316L stainless steel spine rods to observe how the rods mechanically respond in OR contouring. In that study rods were 200 mm long and only the movement at the tip was recorded. The implication of that work was that rods will straighten in-vivo, however, in order for the mechanism of straightening to be determined, the movement of individual bends over time must first be elucidated. Spine rods used were, commercially pure titanium (CP Ti) a primarily α-phase; Ti-6Al-4V; α/β-phase titanium alloy from two different suppliers (denoted by, Ti-6Al-4V (L) and Ti-6Al-4V); β-phase titanium (TNTZ) and CoCrMoC. Following contouring the rods were aged unconstrained, in normal atmosphere or simulated body fluid (SBF) in a CO incubator for up to 288 h. Elastic springback is significantly different between alloys with different microstructures. Both types of Ti6Al4V rods, while meeting the ASTM F136 industry standard, have significantly different properties, most importantly yield strength, flexural modulus, and springback. Environment showed no significant impact on anelasticity. The anelastic response of Ti6Al4V L sample, which has relatively more beta phase than the Ti6Al4V sample, follows the pure beta phase TNTZ in its extended time response. CoCrMoC and CP Ti have a very reduced anelastic response compared to the other alloys. This potentially can have unanticipated effects on the outcome of spine procedures, as the surgeon is reliant on the rods having similar properties to achieve a desired outcome.

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Bending Fatigue and Spring Back Properties of Implant Rods Made of β-Type Titanium Alloy for Spinal Fixture

Cited by 7 publications

References 6 publications

Computer-Aided Design and Manufacturing Technology for Identification of Optimal Nuss Procedure and Fabrication of Patient-Specific Nuss Bar for Minimally Invasive Surgery of Pectus Excavatum

Computer-Aided Design and Manufacturing Technology for Identification of Optimal Nuss Procedure and Fabrication of Patient-Specific Nuss Bar for Minimally Invasive Surgery of Pectus Excavatum

Introduction

Spine rod straightening as a possible cause for revision

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