title: In vivo effects of coating loaded and unloaded Ti implants with collagen, chondroitin sulfate, and hydroxyapatite in the sheep tibia.
abstract: The in vivo effects of coating titanium implants with organic extracellular matrix molecules were examined in the sheep tibia. Titanium screws (5.0 mm) were coated with type I collagen (Ti/Coll) or type I collagen and chondroitin sulfate (Ti/Coll/CS) by biomimetic fibrillogenesis. Uncoated screws (Ti) and screws coated with hydroxyapatite (Ti/HA) served as control. Six adult female sheep received one screw of each type to stabilize a midshaft tibial fracture with external fixation. Four cylindrical implants of 4-mm outer diameter and 3.3-mm inner diameter with the same coatings were inserted into the tibial head. No pin track infections were seen at the time of implant retrieval 6 weeks after implantation. Extraction torque was greater for Ti/HA (1181 Nmm) and Ti/Coll/CS (1088 Nmm) compared to Ti/Coll (900 Nmm) and Ti (904 Nmm) [N.S.]. Newly formed bone was noted around all coated screws within the medullary cavity. Macrophage and osteoclast activity was significantly reduced around Ti/Coll/CS in both types of implants compared to uncoated controls (p < 0.05). Osteoblast activity was significantly increased around loaded Ti/Coll and Ti/Coll/CS screws compared to uncoated Ti screws (p < 0.05). Microtomographic evaluation (SRmicroCT) revealed no significant differences in new bone formation around the unloaded tibial head implants. Coating of external fixation devices with of type I collagen and chondroitin sulfate appears to have similar effects with respect to stability and bone healing as HA but with less osteoclast activity. These findings were more pronounced under loaded than unloaded conditions in the sheeptibia.
authors: Department of Trauma and Reconstructive Surgery, University Hospital Carl Gustav Carus, Fetscherstrasse 74, 01307 Dresden, Germany. strammelt@hotmail.com
authors: Stefan
authors: S
authors: Rammelt
authors: Christian
authors: C
authors: Heck
authors: Ricardo
authors: R
authors: Bernhardt
authors: Susanne
authors: S
authors: Bierbaum
authors: Dieter
authors: D
authors: Scharnweber
authors: Jürgen
authors: J
authors: Goebbels
authors: Jörg
authors: J
authors: Ziegler
authors: Achim
authors: A
authors: Biewener
authors: Hans
authors: H
authors: Zwipp
mesh_terms: D000818:Animals; D001863:Bone Screws; D002809:Chondroitin Sulfates / Q000494:pharmacology*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D024042:Collagen Type I / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D016267:External Fixators; D005592:Fracture Fixation; D020007:Implants, Experimental; D008855:Microscopy, Electron, Scanning; D011859:Radiography; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000628:therapy; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; D024042:Collagen Type I; D002809:Chondroitin Sulfates; D017886:Durapatite; D014025:Titanium