Locally delivered TGF-beta1 and IGF-1 enhance the fixation of titanium implants: a study in dogs.
BACKGROUND
Osteogenic growth factors have been suggested to enhance the fixation of implants used in joint replacement. We examined the effect of locally delivered transforming growth factor-beta1 and insulin-like growth factor-1 in a biodegradable poly (D, L-lactide) coating.


METHODS
In a paired study using 9 dogs, unloaded titanium implants surrounded by a 1-mm gap were inserted into the proximal humerus. The growth factors were incorporated in a poly (D, L-lactide) coating at a 1% (w/w) ratio of TGF-beta1 and a 5% (w/w) ratio of IGF-1. Control implants were uncoated. After 4 weeks, the implants were evaluated by mechanical push-out test and by histomorphometry.


RESULTS
A twofold increase was seen in mechanical fixation (strength, stiffness, energy absorption) for the growth factor-treated implants (p = 0.04). Similar results were seen in histomorphometry, as bone ongrowth was 2.5 times higher (p = 0.02), and gap healing was 30-110% higher (p = 0.04) for the growth factor-treated implants than for the control implants. Ongrowth of fibrous tissue was eliminated by the treatment.


CONCLUSIONS
TGF-beta-1 and IGF-1, locally delivered in a biodegradable poly(D,L-lactide) coating, enhance the mechanical fixation and osseointegration of titanium implants in cancellous bone, and no fibrous tissue is produced in the growth factor treated implants.
Lamberg
Anders
A
Department of Orthopaedic Surgery, Aarhus University Hospital, Denmark.
Schmidmaier
Gerhard
G
Søballe
Kjeld
K
Elmengaard
Brian
B
D000818:Animals; D019643:Arthroplasty, Replacement / Q000379:methods*; D001696:Biomechanical Phenomena; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage*; D004285:Dogs; D006811:Humerus / Q000502:physiology; D020007:Implants, Experimental; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage*; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology; D014025:Titanium; D016212:Transforming Growth Factor beta / Q000008:administration & dosage*
D020099:Coated Materials, Biocompatible; D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I; D014025:Titanium