title: Osteointegration of PLGA implants with nanostructured or microsized β-TCP particles in a minipig model.
abstract: Bioresorbable suture anchors and interference screws have certain benefits over equivalent titanium-alloy implants. However, there is a need for compositional improvement of currently used bioresorbable implants. We hypothesized that implants made of poly(l-lactide-co-glycolide) (PLGA) compounded with nanostructured particles of beta-tricalcium phosphate (β-TCP) would induce stronger osteointegration than implants made of PLGA compounded with microsized β-TCP particles. The experimental nanostructured self-reinforced PLGA (85L:15G)/β-TCP composite was made by high-energy ball-milling. Self-reinforced microsized PLGA (95L:5G)/β-TCP composite was prepared by melt-compounding. The composites were characterized by gas chromatography, Ubbelohde viscometry, scanning electron microscopy, laser diffractometry, and standard mechanical tests. Four groups of implants were prepared for the controlled laboratory study employing a minipig animal model. Implants in the first two groups were prepared from nanostructured and microsized PLGA/β-TCP composites respectively. Microroughened titanium-alloy (Ti6Al4V) implants served as positive intra-animal control, and pure PLGA implants as negative control. Cone-shaped implants were inserted in a random order unilaterally in the anterior cortex of the femoral shaft. Eight weeks after surgery, the mechanical strength of osteointegration of the implants was measured by a push-out test. The quality of new bone surrounding the implant was assessed by microcomputed tomography and histology. Implants made of nanostructured PLGA/β-TCP composite did not show improved mechanical osteointegration compared with the implants made of microsized PLGA/β-TCP composite. In the intra-animal comparison, the push-out force of two PLGA/β-TCP composites was 35-60% of that obtained with Ti6Al4V implants. The implant materials did not result in distinct differences in quality of new bone surrounding the implant.
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, University of Turku and University Hospital of Turku, Turku FI-20520, Finland.
authors.forename: Julia
authors.initials: J
authors.lastname: Kulkova
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, University of Turku and University Hospital of Turku, Turku FI-20520, Finland; Turku Clinical Biomaterials Centre (TCBC), Institute of Dentistry, University of Turku (UTU), Itäinen Pitkäkatu 4 B, FI-20520 Turku, Finland.
authors.forename: Niko
authors.initials: N
authors.lastname: Moritz
authors.affiliation: Conmed Linvatec Biomaterials Ltd., FI-33720 Tampere, Finland.
authors.forename: Esa O
authors.initials: EO
authors.lastname: Suokas
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, University of Turku and University Hospital of Turku, Turku FI-20520, Finland.
authors.forename: Niko
authors.initials: N
authors.lastname: Strandberg
authors.affiliation: Department of Anesthesiology, Turku University Hospital, Turku FI-20520, Finland.
authors.forename: Kari A
authors.initials: KA
authors.lastname: Leino
authors.affiliation: Department of Anesthesiology, Turku University Hospital, Turku FI-20520, Finland.
authors.forename: Timo T
authors.initials: TT
authors.lastname: Laitio
authors.affiliation: Orthopaedic Research Unit, Department of Orthopaedic Surgery and Traumatology, University of Turku and University Hospital of Turku, Turku FI-20520, Finland. Electronic address: hannu.aro@utu.fi.
authors.forename: Hannu T
authors.initials: HT
authors.lastname: Aro
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D002130:Calcium Phosphates / Q000737:chemistry*; D005269:Femur / Q000166:cytology / Q000000981:diagnostic imaging / Q000187:drug effects*; D019344:Lactic Acid / Q000737:chemistry* / Q000494:pharmacology*; D008297:Male; D008422:Materials Testing; D008863:Microspheres; D053761:Nanocomposites / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry* / Q000494:pharmacology*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D013552:Swine; D013556:Swine, Miniature; D055114:X-Ray Microtomography
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
keywords: Beta-tricalcium phosphate; Bioresorbable bone implants; Composite; Minipig; Nanostructure; Poly(l-lactide-co-glycolide)