title: Torque test measurement in segmental bone defects using porous calcium phosphate cement implants.
abstract: This study was performed to assess the bone healing supporting characteristics of porous calcium phosphate (Ca-P) cement when implanted in a rabbit segmental defect model as well as to determine the reliability of torque testing as a method to verify bone healing. The middiaphyseal radius was chosen as the area to create bilaterally increasing defect sizes (5, 10, and 15&#x2009;mm), which were either filled with porous Ca-P cement or left open as a control. After 12 weeks of implantation, torque test measurements as well as histological and radiographic evaluation were performed. In two of the open 15&#x2009;mm control defects, bone bridging was visible at the radiographic and histological evaluation. Bone was observed to be present in all porous Ca-P cement implants (5, 10, and 15&#x2009;mm defects) after 12 weeks. No significant differences in torque measurements were observed between the 5 and 10&#x2009;mm filled and open control defects using a t-test. In addition, the mechanical strength of all operated specimens was similar compared with nonoperated bone samples. The torsion data for the 15&#x2009;mm open defect appeared to be lower compared with the filled 15&#x2009;mm defect, but no significant difference could be proven. Within the limitation of the study design, porous Ca-P cement implants demonstrated osteoconductive properties and confirmed to be a suitable scaffold material in a weight-bearing situation. Further, the used torque testing method was found to be unreliable for testing the mechanical properties of the healed bone defect.
authors.affiliation: Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Henriette C
authors.initials: HC
authors.lastname: Kroese-Deutman
authors.forename: Joop G C
authors.initials: JG
authors.lastname: Wolke
authors.forename: Paul H M
authors.initials: PH
authors.lastname: Spauwen
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
mesh_terms: D000818:Animals; D001843:Bone Cements; D001842:Bone and Bones / Q000002:abnormalities*; D002130:Calcium Phosphates; D005260:Female; D019736:Prostheses and Implants; D011817:Rabbits; D019415:Torque
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; C020243:calcium phosphate