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Journal of Long-Term Effects of Medical Implants
SJR: 0.332 SNIP: 0.491 CiteScore™: 0.89

ISSN Print: 1050-6934
ISSN Online: 1940-4379

Journal of Long-Term Effects of Medical Implants

DOI: 10.1615/JLongTermEffMedImplants.v14.i6.20
12 pages

Hydroxyapatite and Carbon Coatings for Fixation of Unloaded Titanium Implants

Olav Reikeras
Institute of Clinical Medicine, Rikshospitalet University Clinic, University of Oslo, Oslo, Norway
Carina B. Johansson
Department of Biomaterials/Handicap Research, Sahlgrenska University Hospital, Institute for Surgical Sciences, University of Gothenburg, Gothenburg; and Department of Technology, University of Orebro, Orebro, Sweden
Mikael Sundfeldt
Department of Biomaterials/Handicap Research, Institute for Surgical Sciences, University of Göteborg; Department of Orthopaedics, Sahlgrenska University Hospital, Institute for Surgical Sciences, University of Göteborg, Sweden

ABSTRACT

The aim of this study was to investigate the interaction between bone and pure titanium, titanium coated with hydroxyapatite (HA), and titanium coated with carbon in a rat femur model.

In 25 rats, the medullary cavity of both femurs was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 2.0 mm. Nails with a diameter of 2.0 mm and with a length of 34 mm were inserted in a random manner; either a pure titanium nail, a titanium nail entirely plasma-sprayed with a 75−100—μm layer of HA or a titanium nail coated with 2−10-μm carbon. The surface roughness of the pure titanium was characterized by Ra 2.6 μm and Rt 22 μm. Ra of HA was 7.5 μm and Rt 52 μm, and of carbon Ra was 0.4 μm and Rt 4.0 μm. Twelve rats were randomized to a follow up of 8 weeks, and the remaining 13 rats were followed for 16 weeks. At sacrifice both femora were dissected free from soft tissues and then immersed in fixative. A specimen slice of about 5 mm thickness was prepared from the subtrochanteric region with a water-cooled band-saw. Sample preparation for un-decalcified tissue followed the internal guidelines at the laboratories of Biomaterials/Handicap Research. At 8 weeks the median bone bonding contact of the implants was 43% (range 0−74) in the titanium group, 39% (0−75) in the HA group, and 3% (0−59) in the carbon group. At 16 weeks the corresponding figures were 58% (0−78) in the titanium group, 51% (15−75) in the HA group, and 8% (0−79) in the carbon group. In conclusion, we found great variability in bone bonding contact. In general, carbon-coated nails had reduced bone bonding contact both at 8 and at 16 weeks as compared to pure titanium or titanium coated with hydroxyapatite.