title: Tibial implants: biomechanical and histomorphometric studies of hydroxyapatite-coated and uncoated stainless steel and titanium screws in long-term ovariectomized sheep.
abstract: This study was designed to evaluate osteointegration of HA-coated and uncoated titanium and stainless steel screws in the cortical bone of long-term (24 months) ovariectomized sheep (OVX group), in comparison with Sham-aged sheep (control group). The screws were tested biomechanically (extraction torque) and histomorphometrically (affinity index: Al) 12 weeks after their implantation in tibial diaphyses. Tibial cortical bone parameters showed significant differences between the groups, showing a reduction of the selected parameters in the OVX group. ANOVA showed significant effects for both material and ovariectomy factors on obtained extraction torque (material: F=159.26, p < 0.0005; ovariectomy: F=20.04, p < 0.0005) and Al data (material: F=8.04, p < 0.001; ovariectomy: F=7, 17, p < 0.05). In both groups the extraction torque for coated screws of both materials was significantly higher than for uncoated screws, and uncoated titanium had a better extraction torque than uncoated stainless steel. In the OVX group, the HA-coated stainless steel and titanium Al data were significantly higher than uncoated Al data. In conclusion, the biomechanical and histomorphological results obtained suggest employing HA-coated screws in the presence of osteopenic cortical bone.
authors.affiliation: Experimental Surgery Department, Codivilla-Putti Research Institute, Rizzoli Orthopaedic Institute, Bologna, Italy. michele.rocca@ior.it
authors.forename: M
authors.initials: M
authors.lastname: Rocca
authors.forename: M
authors.initials: M
authors.lastname: Fini
authors.forename: G
authors.initials: G
authors.lastname: Giavaresi
authors.forename: N
authors.initials: N
authors.lastname: Nicoli Aldini
authors.forename: R
authors.initials: R
authors.lastname: Giardin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001851:Bone Diseases, Metabolic / Q000601:surgery*; D001863:Bone Screws; D020099:Coated Materials, Biocompatible; D005260:Female; D010052:Ovariectomy; D019736:Prostheses and Implants; D011897:Random Allocation; D012756:Sheep; D013193:Stainless Steel; D013977:Tibia; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; D013193:Stainless Steel; D014025:Titanium