title: Osteointegration of hydroxyapatite-coated and uncoated titanium screws in long-term ovariectomized sheep.
abstract: This study was designed to evaluate the osteointegration of HA-coated and uncoated titanium screws in the cortical bone of long-term (24 months) ovariectomized sheep (OVX group) compared to sham-aged sheep (Control group). At 12 weeks after implantation, the screws were tested biomechanically (extraction torque) and histomorphometrically (affinity index: AI) in both femoral and tibial diaphyses. Cancellous bone status was assessed by iliac crest biopsy. BMD of the L5 vertebra and a histomorphological study of the femoral and tibial shafts were performed to acquire data on cortical bone. A significant difference was found between the OVX and Control groups for BMD (p<0.0005), and a significant reduction in the cancellous bone area was observed in the OVX group. Femoral and tibial cortical bone parameters showed significant differences between the groups. The type of material selected (femurs: p<0.0005; tibiae: p<0.0005) and ovariectomy (femurs: p<0.005; tibiae: p<0.005) had a significant effect on the extraction torque. AI results were related to the presence or absence of ovariectomy (p<0.05) and strictly depended on the material implanted in the femur and tibia (p<0.0005). In conclusion, at implantation OVX sheep showed a significant loss of trabecular and cortical bone versus sham-aged sheep. The biomechanical and histomorphological results achieved suggest employing HA-coated screws in the presence of osteopenic cortical bone.
authors.affiliation: Experimental Surgery Department, Istituto di Ricerca Codivilla-Putti, Rizzoli Orthopaedic Institute-IOR, Bologna, Italy. michele.rocca@ior.it
authors.forename: Michele
authors.initials: M
authors.lastname: Rocca
authors.forename: Milena
authors.initials: M
authors.lastname: Fini
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giavaresi
authors.forename: Nicolò Nicoli
authors.initials: NN
authors.lastname: Aldini
authors.forename: Roberto
authors.initials: R
authors.lastname: Giardino
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D001863:Bone Screws; D017886:Durapatite; D005260:Female; D008422:Materials Testing; D016348:Osseointegration; D010052:Ovariectomy / Q000009:adverse effects; D012756:Sheep; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D017886:Durapatite; D014025:Titanium