title: Effects of bone morphogenetic protein-2 and hyaluronic acid on the osseointegration of hydroxyapatite-coated implants: an experimental study in sheep.
abstract: Research efforts aim at enhancing early osseointegration of cementless implants to improve early fixation and, thus, reduce the risk of loosening. The aim of the present study was to investigate whether bone morphogenetic protein (BMP) 2 had a positive effect on the osseointegration of hydroxyapatite-coated implants. Hydroxyapatite (HA) implants (perforated hollow cylinders and solid rods) were coated with BMP-2 and hyaluronic acid (HY) as the carrier or with HY alone. Uncoated HA implants served as controls. The osseointegration of the implants was evaluated either by light microscopy or by pullout tests after 1, 2, and 4 weeks of unloaded implantation in the cancellous bone of 24 sheep. The BMP-2 coating significantly increased bone growth into the implant perforations compared with HA-coated implants at 2 and 4 weeks. Bone-implant contact and interface shear strength of BMP-2 implants were lower than HA implants at 2 weeks. At 4 weeks, there was no significant difference in bone-implant contact and shear strength between BMP-2 and HA-coated implants. The BMP-2 coating enhanced gap healing but had no positive or even an inhibitory effect (at 2 weeks) on bone-implant contact and interface shear strength. In the clinical situation, a perfect press-fit implantation cannot be achieved, and BMP-2 may be beneficial for enhancing bone growth into gaps around cementless implants.
authors.affiliation: Department of Orthopaedic Surgery, Princess Alexandra Hospital, Woolloongabba, Australia.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Aebli
authors.forename: Hermann
authors.initials: H
authors.lastname: Stich
authors.forename: Peter
authors.initials: P
authors.lastname: Schawalder
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Theis
authors.forename: Jörg
authors.initials: J
authors.lastname: Krebs
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D020099:Coated Materials, Biocompatible / Q000378:metabolism*; D005260:Female; D005269:Femur / Q000166:cytology / Q000378:metabolism; D006820:Hyaluronic Acid / Q000378:metabolism*; D006882:Hydroxyapatites / Q000378:metabolism*; D008422:Materials Testing; D016348:Osseointegration; D019736:Prostheses and Implants; D033081:Shear Strength; D012756:Sheep; D013314:Stress, Mechanical; D013499:Surface Properties; D013977:Tibia / Q000166:cytology / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D020099:Coated Materials, Biocompatible; D006882:Hydroxyapatites; D016212:Transforming Growth Factor beta; D006820:Hyaluronic Acid