title: Glycerol-l-lactide coating polymer leads to delay in bone ingrowth in hydroxyapatite implants.
abstract: Glycerol-l-lactide as coating polymer for the delivery of basic fibroblast growth factor (bFGF) from hydroxyapatite (HA) ceramic implants was shown to lead to significant delay in bone ingrowth into the implants compared to implants without the coating polymer. The purpose of this work was to study bone ingrowth in HA ceramic implants with and without the coating polymer but without growth factors to enable differentiation between a locking effect of the pores by the polymer and the fact of inactivation of the growth factors by the polymer, which could both be possible for the delay. A defect was created in the subchondral region of both femurs in 24 miniature-pigs and was either filled by the HA implants with or without the coating polymer. Histomorphometry showed a significant delay in bone ingrowth in the polymer coated implants both after 6 and 12 weeks. Detailed histology revealed that the HA pores were completely "locked" by the polymer leading to complete loss of the osteoconductive properties of the HA. Also electron microscopy showed filling of the HA pores by the polymer. Therefore, it can be concluded that glycerol-l-lactide should not be used to coat HA ceramic implants due to significant delay in bone ingrowth.
authors.affiliation: Department of Trauma Surgery, University Hospital Giessen, Rudolf-Buchheim-Str. 7, 35385 Giessen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schnettler
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Pfefferle
authors.forename: Olaf
authors.initials: O
authors.lastname: Kilian
authors.forename: Christian
authors.initials: C
authors.lastname: Heiss
authors.forename: Jörg
authors.initials: J
authors.lastname: Kreuter
authors.forename: Dirk
authors.initials: D
authors.lastname: Lommel
authors.forename: Theodoros
authors.initials: T
authors.lastname: Pavlidis
authors.forename: Jens-Peter
authors.initials: JP
authors.lastname: Stahl
authors.forename: Christof
authors.initials: C
authors.lastname: Meyer
authors.forename: Sabine
authors.initials: S
authors.lastname: Wenisch
authors.forename: Volker
authors.initials: V
authors.lastname: Alt
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000008:administration & dosage / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage / Q000737:chemistry*; D017886:Durapatite / Q000008:administration & dosage / Q000737:chemistry*; D016222:Fibroblast Growth Factor 2 / Q000008:administration & dosage*; D008297:Male; D016348:Osseointegration / Q000187:drug effects*; D011091:Polyesters / Q000008:administration & dosage / Q000737:chemistry*; D019736:Prostheses and Implants; D013552:Swine; D013556:Swine, Miniature
chemical_list: D018786:Bone Substitutes; D020099:Coated Materials, Biocompatible; D011091:Polyesters; C496968:glycerol lactide polymer; D016222:Fibroblast Growth Factor 2; D017886:Durapatite