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Effect of local TGF-beta1 and IGF-1 release on implant fixation: comparison with hydroxyapatite coating: a paired study in dogs.

Lamberg A, Bechtold JE, Baas J, Søballe K, Elmengaard B - Acta Orthop (2009)

Bottom Line: Here, we have compared the effect of local release of TGF-beta1 and IGF-1 with that of hydroxyapatite coating on implant fixation.There was no difference in any of the mechanical parameters.While HA mainly stimulated bone ongrowth, local release of TGF-beta1 and IGF-1 stimulated gap healing.

View Article: PubMed Central - PubMed

Affiliation: Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark. anders@lamberg.dk

ABSTRACT

Background and purpose: Hydroxyapatite (HA) coating stimulates the osseointegration of cementless orthopedic implants. Recently, locally released osteogenic growth factors have also been shown experimentally to stimulate osseointegration so that bone fills gaps around orthopedic implants. Here, we have compared the effect of local release of TGF-beta1 and IGF-1 with that of hydroxyapatite coating on implant fixation.

Method: Weight-bearing implants with a 0.75-mm surrounding gap were inserted bilaterally in the knees of 10 dogs. Growth factors were incorporated in a biodegradable poly(D,L-lactide) coating on porous coated titanium implants. Plasma-sprayed HA implants served as controls. The dogs were killed at 4 weeks and the implants were evaluated by mechanical push-out test and by histomorphometry.

Results: There was no difference in any of the mechanical parameters. Bone ongrowth was 3-fold higher for HA-coated implants (p < 0.001). For growth factor-coated implants, bone volume was 26% higher in the inner half of the gap and 28% higher in the outer half compared to HA (p < 0.03).

Interpretation: The mechanical fixation of porous-coated titanium implants with local growth factor release is comparable to that of HA coating. While HA mainly stimulated bone ongrowth, local release of TGF-beta1 and IGF-1 stimulated gap healing.

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Images from histomorphometry. A. hydroxyapatite-coated implant. B. Growth factor-coated implant. The lines indicate the inner and outer zones where the tissue volume is measured. Ongrowth is defined as tissue in direct contact with the implant surface or the hydroxyapatite coating.
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Figure 0002: Images from histomorphometry. A. hydroxyapatite-coated implant. B. Growth factor-coated implant. The lines indicate the inner and outer zones where the tissue volume is measured. Ongrowth is defined as tissue in direct contact with the implant surface or the hydroxyapatite coating.

Mentions: The specimens underwent random vertical sectioning on a Leiden microtome (Leiden, Holland), and were counterstained with 2% light green (Overgaard et al. 2000). The analyses were done with Cast grid software (Olympus). The obvious presence of hydroxyapatite on the control implants made true blinding impossible, but the examiner did not know which implant was the pair match. We quantified bone and fibrous tissue by stereological principles (Gundersen et al. 1988). The ongrowth was estimated using line interception technique and the gap volume fractions were estimated by point interception technique. The gap was divided into 2 zones: the inner zone adjacent to the implant surface, and the outer zone adjacent to the edge of the drill hole (Figure 2).


Effect of local TGF-beta1 and IGF-1 release on implant fixation: comparison with hydroxyapatite coating: a paired study in dogs.

Lamberg A, Bechtold JE, Baas J, Søballe K, Elmengaard B - Acta Orthop (2009)

Images from histomorphometry. A. hydroxyapatite-coated implant. B. Growth factor-coated implant. The lines indicate the inner and outer zones where the tissue volume is measured. Ongrowth is defined as tissue in direct contact with the implant surface or the hydroxyapatite coating.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823183&req=5

Figure 0002: Images from histomorphometry. A. hydroxyapatite-coated implant. B. Growth factor-coated implant. The lines indicate the inner and outer zones where the tissue volume is measured. Ongrowth is defined as tissue in direct contact with the implant surface or the hydroxyapatite coating.
Mentions: The specimens underwent random vertical sectioning on a Leiden microtome (Leiden, Holland), and were counterstained with 2% light green (Overgaard et al. 2000). The analyses were done with Cast grid software (Olympus). The obvious presence of hydroxyapatite on the control implants made true blinding impossible, but the examiner did not know which implant was the pair match. We quantified bone and fibrous tissue by stereological principles (Gundersen et al. 1988). The ongrowth was estimated using line interception technique and the gap volume fractions were estimated by point interception technique. The gap was divided into 2 zones: the inner zone adjacent to the implant surface, and the outer zone adjacent to the edge of the drill hole (Figure 2).

Bottom Line: Here, we have compared the effect of local release of TGF-beta1 and IGF-1 with that of hydroxyapatite coating on implant fixation.There was no difference in any of the mechanical parameters.While HA mainly stimulated bone ongrowth, local release of TGF-beta1 and IGF-1 stimulated gap healing.

View Article: PubMed Central - PubMed

Affiliation: Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark. anders@lamberg.dk

ABSTRACT

Background and purpose: Hydroxyapatite (HA) coating stimulates the osseointegration of cementless orthopedic implants. Recently, locally released osteogenic growth factors have also been shown experimentally to stimulate osseointegration so that bone fills gaps around orthopedic implants. Here, we have compared the effect of local release of TGF-beta1 and IGF-1 with that of hydroxyapatite coating on implant fixation.

Method: Weight-bearing implants with a 0.75-mm surrounding gap were inserted bilaterally in the knees of 10 dogs. Growth factors were incorporated in a biodegradable poly(D,L-lactide) coating on porous coated titanium implants. Plasma-sprayed HA implants served as controls. The dogs were killed at 4 weeks and the implants were evaluated by mechanical push-out test and by histomorphometry.

Results: There was no difference in any of the mechanical parameters. Bone ongrowth was 3-fold higher for HA-coated implants (p < 0.001). For growth factor-coated implants, bone volume was 26% higher in the inner half of the gap and 28% higher in the outer half compared to HA (p < 0.03).

Interpretation: The mechanical fixation of porous-coated titanium implants with local growth factor release is comparable to that of HA coating. While HA mainly stimulated bone ongrowth, local release of TGF-beta1 and IGF-1 stimulated gap healing.

Show MeSH
Related in: MedlinePlus