title: Surface enhancements accelerate bone bonding to CPC-coated strain gauges.
abstract: Calcium phosphate ceramic (CPC)-coated strain gauges have been used for in vivo bone strain measurements for up to 18 weeks, but they require 6 to 9 weeks for sufficient bonding. Osteogenic protein-1 (OP-1), PepTite (a proprietary ligand), calcium sulfate dihydrate (CSD), transforming growth factor beta-1 (TGF-beta1 ), and an endothelial cell layer with and without TGF-beta1 were used as surface enhancements to accelerate bone-to-CPC bonding. Young male Sprague-Dawley rats were implanted with unenhanced and enhanced CPC-coated gauges. Animals were allowed normal activity for 3 weeks and then calcein labeled. Femurs were explanted following euthanasia. A gauge was attached with cyanoacrylate to the opposite femur in the same position as the CPC-coated gauge. Bones were cantilever-loaded to assess strain transfer. They were sectioned and stained with mineralized bone stain (MIBS) and examined with transmitted and ultraviolet light. Mechanical testing indicated increased sensing accuracy for TGF-beta1 and OP-1 enhancements to 105 +/- 14% and 92 +/- 12% versus 52 +/- 44% for the unenhanced gauges. The PepTite and the endothelial-cell-layer-enhanced gauges showed lower sensing accuracy, and histology revealed a vascular layer near CPC particles. TGF-beta1 increased bone formation when used prior to endothelial cell sodding. CSD prevented strain transfer to the femur. TGF-beta1 and OP-1 surface enhancements produced accurate in vivo strain sensing on the rat femur after 3 weeks.
authors: Orthopaedic Research Laboratory, Department of Orthopedic Surgery and Biomedical Engineering Interdisciplinary Program, University of Arizona, Tucson 85724, USA.
authors: N M
authors: NM
authors: Cordaro
authors: J A
authors: JA
authors: Szivek
authors: D W
authors: DW
authors: DeYoung
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002130:Calcium Phosphates; D002133:Calcium Sulfate / Q000494:pharmacology*; D002516:Ceramics; D020099:Coated Materials, Biocompatible; D004727:Endothelium / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D005269:Femur / Q000033:anatomy & histology / Q000187:drug effects*; D005500:Follow-Up Studies; D007700:Kinetics; D008024:Ligands; D008297:Male; D008422:Materials Testing; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013499:Surface Properties; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
chemical_list: D001672:Biocompatible Materials; C525821:Bmp7 protein, rat; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D008024:Ligands; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D002133:Calcium Sulfate