Clinical and Translational Research
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Feb 6, 2020; 8(3): 504-516
Published online Feb 6, 2020. doi: 10.12998/wjcc.v8.i3.504
Novel zinc alloys for biodegradable surgical staples
Hizuru Amano, Koichi Miyake, Akinari Hinoki, Kazuki Yokota, Fumie Kinoshita, Atsuko Nakazawa, Yujiro Tanaka, Yasuhiro Seto, Hiroo Uchida
Hizuru Amano, Department of Pediatric Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
Koichi Miyake, Yasuhiro Seto, Mitsui Mining and Smelting Co., Ltd., Tokyo 141-0032, Japan
Akinari Hinoki, Kazuki Yokota, Yujiro Tanaka, Hiroo Uchida, Department of Pediatric Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
Fumie Kinoshita, Department of Advanced Medicine, Nagoya University Hospital, Nagoya 466-8560, Japan
Atsuko Nakazawa, Department of Clinical Research, Saitama Children’s Medical Center, Saitama 330-8777, Japan
Author contributions: Amano H, Miyake K, Hinoki A, Seto Y, and Uchida H designed and coordinated the research; Amano H, Miyake K, Hinoki A, Yokota K, and Uchida H performed the experiments; Amano H, Miyake K, Hinoki A, Kinoshita F, Nakazawa A, Tanaka Y, Seto Y, and Uchida H analyzed the data; Amano H and Miyake K wrote the paper; Amano H, Miyake K, Hinoki A, Yokota K, Tanaka Y, Seto Y, and Uchida H revised this paper critically.
Institutional animal care and use committee statement: This experiment was approved by the Animal Experiment Committee of Nagoya University (Approval ID: 31354).
Conflict-of-interest statement: The authors have no conflict of interest to declare.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Hiroo Uchida MD, PhD, Professor, Chairman, Department of Pediatric Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 466-8550, Japan. hiro2013@med.nagoya-u.ac.jp
Received: September 3, 2019
Peer-review started: September 3, 2019
First decision: October 14, 2019
Revised: December 14, 2019
Accepted: December 21, 2019
Article in press: December 21, 2019
Published online: February 6, 2020
Processing time: 155 Days and 17.6 Hours
ARTICLE HIGHLIGHTS
Research background

Surgical staples are widely used in all types of surgery. However, they are manufactured from non-biodegradable Ti or Ti alloys, meaning they exist permanently within the human body; this has resulted in reports of adverse effects, including allergic and foreign-body reactions and adhesion. Therefore, the development of biodegradable surgical staples is desirable. In order to develop a biodegradable alloy suitable for the fabrication of surgical staples, we focused on Zn, which is a known biodegradable metal. In this study, we developed novel Zn alloys with superior mechanical properties compared to the conventional Zn alloys that were suitable for fabricating surgical staples.

Research motivation

Zn has recently been the focus of research as a novel implant metal owing to its good biocompatibility and biodegradability. However, there are no extant reports on Zn-based staples owing to its low mechanical strength.

Research objectives

The objective of this study is to investigate the in vitro mechanical properties and degradation behaviors as well as in vivo safety and feasibility of biodegradable Zn alloy staples.

Research methods

Tensile and bending tests were conducted to evaluate the mechanical properties of binary Zn alloys with 0.1–6 wt.% Mg, Ca, Mn, Cu, or Ti. Based on the results, three promising Zn alloy compositions were evaluated for staple applications (wt.%): Zn-1.0Cu-0.2Mn-0.1Ti (Zn alloy 1), Zn-1.0Mn-0.1Ti (Zn alloy 2), and Zn-1.0Cu-0.1Ti (Zn alloy 3). Immersion tests were performed using fed-state simulated intestinal fluid (FeSSIF) and Hank's balanced salt solution (HBSS). The corrosion rates were estimated from the weight losses of the staples during immersion. Nine rabbits were used as test subjects for gastric resection using each of the Zn alloy staples, and a clinically available Ti staple was used on another group of nine rabbits. Three rabbits in each group were euthanized at 1, 4, and 12 wk post operation.

Research results

Additions of ≤1 wt.% Mn or Cu and 0.1 wt.% Ti improved the yield strength without excessive deterioration of elongation or bendability. Immersion tests revealed no staple fractures in any of the Zn alloy staples. The corrosion rates of Zn alloy staples 1, 2, and 3 were 0.02 mm/year in HBSS and 0.12, 0.11, and 0.13 mm/year, respectively, in FeSSIF. These degradation times are sufficient for wound healing. In the animal study, none of the Zn alloy staples resulted in technical failures, and all rabbits survived without complications. Histopathological analysis revealed no severe inflammatory reactions around the Zn alloy staples.

Research conclusions

Staples made of Zn-1.0Cu-0.2Mn-0.1Ti, Zn-1.0Mn-0.1Ti, and Zn-1.0Cu-0.1Ti exhibit acceptable in vitro mechanical properties, appropriate degradation behavior, and in vivo safety and feasibility.

Research perspectives

Zn alloy staples are proposed as promising candidates for biodegradable staples to replace the currently available Ti alloy staple.