Osteointegration of PLGA implants with nanostructured or microsized β-TCP particles in a minipig model

Julia Kulkova, Niko Moritz, Esa O. Suokas, Niko Strandberg, Kari A. Leino, Timo T. Laitio, Hannu T. Aro

    Research output: Contribution to journalArticleScientificpeer-review

    11 Citations (Scopus)


    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.

    Original languageEnglish
    Pages (from-to)190-200
    Number of pages11
    JournalJournal of the Mechanical Behavior of Biomedical Materials
    Publication statusPublished - 1 Dec 2014
    Publication typeA1 Journal article-refereed


    • Beta-tricalcium phosphate
    • Bioresorbable bone implants
    • Composite
    • Minipig
    • Nanostructure
    • Poly(l-lactide-co-glycolide)

    ASJC Scopus subject areas

    • Biomaterials
    • Biomedical Engineering
    • Mechanics of Materials
    • Medicine(all)

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