title: Assessment of the RIVET fixation system for cranioplasty using the pull-out technique.
abstract: Cranioplasty using custom-made hydroxyapatite (HAP) ceramic implants is a common procedure to repair skull defects. However, commercially available titanium screws are only minimally stabilized due to characteristic brittleness. We developed the RIVET technique which involves fixing a bioabsorbable plate atop a HAP block using bioabsorbable screws extending beyond both layers, and evaluated fixation strength using the pull-out test and microtomography. Three experimental conditions were compared: a non-RIVET group, RIVET group, and dry skull control group. Pull-out strength significantly differed across groups (non-RIVET group, 1.33 ± 1.21 kgf; RIVET group, 4.46 ± 0.84 kgf; and control group, 6.99 ± 1.14 kgf, P < 0.01). Microtomography of the dry skull control group revealed thread grooves fitted to the screws. The non-RIVET and RIVET groups presented fewer thread grooves than the control group, and the screws did not fit perfectly to the HAP block. However, fixation in the RIVET group was more stable, as the rivet was firmly lodged into the implant. In conclusion, by melting and creating the rivet, pull-out strength can be increased and rigid stabilization of HAP can be obtained. This technique uses commercially available absorbable plate and screws, and thus can be used widely in clinical applications involving HAP blocks with different porosities and thicknesses.
authors.affiliation: Department of Plastic and Reconstructive Surgery (Head Prof. Kazuo Kishi), Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ward, Tokyo 160-8582, Japan. Electronic address: ysakamoto@z8.keio.jp.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sakamoto
authors.affiliation: Department of Plastic and Reconstructive Surgery, Saitama Medical Center, 1981, Kamoda, Kawagoe-City, Saitama, 350-8550, Japan.
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Minabe
authors.affiliation: Department of Plastic and Reconstructive Surgery (Head Prof. Kazuo Kishi), Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ward, Tokyo 160-8582, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Plastic and Reconstructive Surgery (Head Prof. Kazuo Kishi), Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ward, Tokyo 160-8582, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kishi
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000737:chemistry; D001860:Bone Plates; D001863:Bone Screws; D002516:Ceramics / Q000737:chemistry; D003399:Craniotomy / Q000295:instrumentation*; D017886:Durapatite / Q000737:chemistry; D004867:Equipment Design; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D009984:Orthopedic Fixation Devices; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D019651:Plastic Surgery Procedures / Q000295:instrumentation*; D013314:Stress, Mechanical; D013499:Surface Properties; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D017886:Durapatite
keywords: Bioabsorbable fixation; Cranial defect; Cranioplasty; Hydroxyapatite; Physical strength; Skull defect