title: In vitro and in vivo studies on the degradation of high-purity Mg (99.99wt.%) screw with femoral intracondylar fractured rabbit model.
abstract: High-purity magnesium (HP Mg) takes advantage in no alloying toxic elements and slower degradation rate in lack of second phases and micro-galvanic corrosion. In this study, as rolled HP Mg was fabricated into screws and went through in vitro immersion tests, cytotoxicity test and bioactive analysis. The HP Mg screws performed uniform corrosion behavior in vitro, and its extraction promoted cell viability, bone alkaline phosphatase (ALP) activity, and mRNA expression of osteogenic differentiation related gene, i.e. ALP, osteopontin (OPN) and RUNX2 of human bone marrow mesenchymal stem cells (hBMSCs). Then HP Mg screws were implanted in vivo as load-bearing implant to fix bone fracture and subsequently gross observation, range of motion (ROM), X-ray scanning, qualitative micro-computed tomography (μCT) analysis, histological analysis, bending-force test and SEM morphology of retrieved screws were performed respectively at 4, 8, 16 and 24 weeks. As a result, the retrieved HP Mg screws in fixation of rabbit femoral intracondylar fracture showed uniform degradation morphology and enough bending force. However, part of PLLA screws was broken in bolt, although its screw thread was still intact. Good osseointegration was revealed surrounding HP Mg screws and increased bone volume and bone mineral density were detected at fracture gap, indicating the rigid fixation and enhanced fracture healing process provided by HP Mg screws. Consequently, the HP Mg showed great potential as internal fixation devices in intra-articular fracture operation.
authors.affiliation: Orthopaedic Department, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Han
authors.affiliation: Orthopaedic Department, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Suzhou Origin Medical Technology Co. Ltd., Suzhou 215513, China.
authors.forename: Shaoxiang
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: zcl@sjtu.edu.cn.
authors.forename: Changli
authors.initials: C
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Jiahua
authors.initials: J
authors.lastname: Ni
authors.affiliation: Suzhou Origin Medical Technology Co. Ltd., Suzhou 215513, China.
authors.forename: Yuanzhuang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Orthopaedic Department, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
authors.forename: Wanrun
authors.initials: W
authors.lastname: Zhong
authors.affiliation: Orthopaedic Department, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Hou
authors.affiliation: State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Suzhou Origin Medical Technology Co. Ltd., Suzhou 215513, China.
authors.forename: Xiaonong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Orthopaedic Department, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China. Electronic address: chaiyimin@vip.163.com.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Chai
mesh_terms: D020341:Absorbable Implants; D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D001863:Bone Screws; D003343:Corrosion; D019544:Equipment Failure Analysis; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017102:Fracture Healing; D066298:In Vitro Techniques; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D019344:Lactic Acid; D008274:Magnesium; D008422:Materials Testing; D016348:Osseointegration; D010012:Osteogenesis / Q000235:genetics; D011091:Polyesters; D011108:Polymers; D011817:Rabbits; D011897:Random Allocation; D016059:Range of Motion, Articular; D060888:Real-Time Polymerase Chain Reaction; D016474:Weight-Bearing; D055114:X-Ray Microtomography
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D000469:Alkaline Phosphatase; D008274:Magnesium
keywords: Bone healing; Fracture fixation; High-purity magnesium; Load-bearing; Osseointegration