title: The effect of enzymatically degradable IPN coatings on peri-implant bone formation and implant fixation.
abstract: Short-term osseointegration of orthopedic implants is critical for the long-term stability of the implant-bone interface. To improve initial implant stability, one strategy under consideration involves the presentation of adhesion ligands on the implant surface to stimulate bone regeneration in the peri-implant region. To assess the relative effects of implant surface chemistry and topography on osseointegration within the rat femoral ablation implant model, a nonfouling, enzymatically degradable interpenetrating polymer network (edIPN) of poly(AAm-co-EG/AAc) amenable to presenting the cell signaling domain Arg-Gly-Asp (RGD), was developed. Moderate enhancement of peri-implant bone formation was found after 28 days using the edIPN without peptide modification (p = 0.032). However, no data supported a benefit of peptide modification, as bone-implant contact, normalized bone volume and normalized fixation strength was equivalent or poorer than dual acid-etched (DAE) treated implants after 28 days. Surface topography was determined to be the dominant factor in modulating osseointegration, as DAE implants produced equivalent roughness-normalized fixation strength versus previously reported data on plasma-sprayed hydroxyapatite/tricalcium phosphate-coated implants (Barber et al., J Biomed Mater Res A, forthcoming). An ideal osseointegrated implant will require optimization of all three aforementioned parameters, and may take the form of biomolecule delivery from thin degradable polymer networks.
authors.affiliation: Department of Bioengineering, University of California at Berkeley, Berkeley, California 94720-1760.
authors.forename: James E
authors.initials: JE
authors.lastname: Ho
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Barber
authors.forename: Amarjit S
authors.initials: AS
authors.lastname: Virdi
authors.forename: Dale R
authors.initials: DR
authors.lastname: Sumner
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Healy
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D020007:Implants, Experimental; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis / Q000502:physiology*; D011108:Polymers / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties; D013997:Time Factors
chemical_list: D011108:Polymers; D053509:Matrix Metalloproteinase 13