title: Analysis of the osseointegrative force of a hyperhydrophilic and nanostructured surface refinement for TPS surfaces in a gap healing model with the Göttingen minipig.
abstract: BACKGROUND
  A lot of advantages can result in a high wettability as well as a nanostructure at a titanium surface on bone implants. Thus, the aim of this study was to evaluate the osseointegrative potential of a titan plasma-sprayed (TPS) surface refinement by acid-etching with chromosulfuric acid. This results in a hyperhydrophilic surface with a nanostructure and an extreme high wetting rate.
  
  
  METHODS
  In total, 72 dumbbell shape titan implants were inserted in the spongy bone of the femora of 18 Göttingen minipigs in a conservative gap model. Thirty-six titan implants were coated with a standard TPS surface and 36 with the hyperhydrophilic chromosulfuric acid (CSA) surface. After a healing period of 4, 8, and 12 weeks, the animals were killed. The chronological healing process was histomorphometrically analyzed.
  
  
  RESULTS
  The de novo bone formation, represented by the bone area (BA), is increased by approximately 1.5 times after 12 weeks with little additional benefit by use of the CSA surface. The bone-to-implant contact (BIC), which represents osseoconductive forces, shows results with a highly increased osteoid production in the CSA implants beginning at 8 and 12 weeks compared to TPS. This culminates in a 17-fold increase in BIC after a healing period of 12 weeks. After 4 weeks, significantly more osteoid was seen in the gap as de novo formation in the CSA group (p = 0.0062). Osteoid was also found more frequently after 12 weeks at the CSA-treated surface (p = 0.0355). The site of implantation, intertrochanteric or intercondylar, may influence on the de novo bone formation in the gap.
  
  
  CONCLUSIONS
  There is a benefit by the CSA surface treatment of the TPS layer for osseointegration over an observation time up to 12 weeks. Significant differences were able to be shown in two direct comparisons between the CSA and the TPS surface for osteoid formation in the gap model. Further trials may reveal the benefit of the CSA treatment of the TPS layer involving mechanical tests if possible.
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.|Department of Anesthesia and Intensive Care Medicine, Asklepios Südpfalzklinik Kandel, Luitpoldstr. 14, 76870, Kandel, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Seidling
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.|Clinic of Trauma and Hand Surgery, Vincentius-Kliniken gAG Karlsruhe, Südendstr. 32, 76137, Karlsruhe, Germany.
authors.forename: Lars J
authors.initials: LJ
authors.lastname: Lehmann
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.|Clinic for Anaesthesia, Intensive Care and Pain Therapy, BG Trauma Centre, Ludwig-Guttmann-Str. 13, 67071, Ludwigshafen, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Lingner
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.|Department for Anesthesia, Surgical Intensive Care, Prehospital Emergency Medicine and Pain Therapy, University Hospital Basel, Spitalstrasse 21, 4031, Basel, Switzerland.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Mauermann
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Obertacke
authors.affiliation: Department for Experimental Orthopaedics and Trauma Surgery, Orthopaedic and Trauma Surgery Centre (OUZ), University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany. markus.schwarz@medma.uni-heidelberg.de.
authors.forename: Markus L R
authors.initials: ML
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D005260:Female; D005269:Femur / Q000601:surgery*; D020007:Implants, Experimental; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D049329:Nanostructures; D016348:Osseointegration / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology; D013314:Stress, Mechanical; D013499:Surface Properties; D013552:Swine; D013556:Swine, Miniature; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; D014025:Titanium
keywords: Gap model; Hyperhydrophilicity; Minipig; Nanostructure; Osseointegration; TPS