title: Polypyrrole coating on poly-(lactide/glycolide)-β-tricalcium phosphate screws enhances new bone formation in rabbits.
abstract: Polypyrrole (PPy) has gained interest as an implant material due to its multifunctional properties and its high compatibility with several cell and tissue types. For the first time, the biocompatibility and osteointegration of PPy coating, incorporated with chondroitin sulfate (CS), were studied in vivo by implanting PPy-coated bioabsorbable bone fixation composite screws of poly-(lactide/glycolide) copolymer (PLGA) and β-tricalcium phosphate (TCP) into New Zealand white rabbits. Uncoated bioabsorbable polymer composite screws and commercially available stainless steel cortical screws were used as reference implants. The rabbits were euthanized 12 and 26 weeks after the implantation. The systemic effects were evaluated from food and water consumption, body weight, body temperature, clinical signs, blood samples, internal organ weights, and histological examination. Local effects were studied from bone tissue and surrounding soft tissue histology. New bone formation was evaluated by micro-computed tomography, tetracycline labeling and torsion tests. Torsion tests were performed in order to capture the peak value of the torsion force during the course of the screw's loosening. The coated screws induced significantly more bone formation than the uncoated screws. In addition, none of the implants induced any systemic or local toxicity. The results suggest that PPy is biocompatible with bone tissue and is a potential coating for enhancing osteointegration in orthopedic implants.
authors.affiliation: Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China. Department of Orthopaedic Surgery, Jinshan Hospital, Fudan University, Shanghai 201508, People's Republic of China.
authors.forename: Ming-Dong
authors.initials: MD
authors.lastname: Zhao
authors.forename: Miina
authors.initials: M
authors.lastname: Björninen
authors.forename: Lu
authors.initials: L
authors.lastname: Cao
authors.forename: Hui-Ren
authors.initials: HR
authors.lastname: Wang
authors.forename: Jani
authors.initials: J
authors.lastname: Pelto
authors.forename: Xiang-Qian
authors.initials: XQ
authors.lastname: Li
authors.forename: Jari
authors.initials: J
authors.lastname: Hyttinen
authors.forename: Yun-Qi
authors.initials: YQ
authors.lastname: Jiang
authors.forename: Minna
authors.initials: M
authors.lastname: Kellomäki
authors.forename: Susanna
authors.initials: S
authors.lastname: Miettinen
authors.forename: George K
authors.initials: GK
authors.lastname: Sándor
authors.forename: Riitta
authors.initials: R
authors.lastname: Seppänen
authors.forename: Suvi
authors.initials: S
authors.lastname: Haimi
authors.forename: Jian
authors.initials: J
authors.lastname: Dong
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001863:Bone Screws; D002130:Calcium Phosphates / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D010012:Osteogenesis / Q000502:physiology*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D011817:Rabbits
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D011108:Polymers; D011758:Pyrroles; C485828:alpha-tricalcium phosphate; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; C067635:polypyrrole; D019344:Lactic Acid