Effect of surface roughness, porosity, and a resorbable calcium phosphate coating on osseointegration of titanium in a minipig model

• Published in: Journal of Biomedical Materials Research Part B 2009-06, Vol.89A (3), p.667-678
• Main Authors: Schwarz, Markus L. R., Kowarsch, Markus, Rose, Steffen, Becker, Kristianna, Lenz, Tamara, Jani, Lutz
• Format: Article
• Language: English
• Subjects: Animals; Biomechanical Phenomena - drug effects; Calcium Phosphates - pharmacology; Coated Materials, Biocompatible - pharmacology; Femur - diagnostic imaging; Femur - drug effects; Femur - surgery; histomorphometry; Implants, Experimental; minipig; Models, Animal; osseointegration; Osseointegration - drug effects; Porosity - drug effects; pull-out tests; Radiography; Regression Analysis; resorbable coating; Shear Strength - drug effects; Surface Properties - drug effects; Swine; Swine, Miniature; Titanium - pharmacology; titanium implants
• ISSN: 1549-3296; 1552-4965; 1552-4981
• DOI: 10.1002/jbm.a.32000

The aim of this study was to compare the osseointegration of four different implant surfaces in the Göttingen minipig femur model. They were prepared by glasspearlblasting (A), sandblasting (B) and titaniumplasma spraying (C and D). Surface D received additionally an electrochemically deposited layer of a resorbable calcium phosphate (CaP) layer, made mainly of brushite. Sample size was n = 20 per group. Implants were placed in the intertrochanteric and intercondylar sites of both femora. After 12 weeks, implant anchorage was measured by the pull‐out test and histomorphometry measurements were carried out at the bone‐implant interface. Implant anchorage was 0.7 ± 0.3 MPa for surface A, 3.2 ± 0.6 MPa for surface B, 6.5 ± 1.5 MPa for surface C and 7.3 ± 1.9 MPa for surface D. The differences between surfaces were statistically significant, with exception of C and D. The stiffness of the bone‐implant interface showed no statistically significant difference between surfaces. After pull‐out, surface A and B showed nearly no bone spots, while on surfaces C and D bone remains were found. Bone‐implant contact was 1.9 ± 1.1% for surface A, 10.5 ± 3.6% for surface B, 22.4 ± 4.5% for surface C and 48.8 ± 4.5% for surface D. The differences were statistically significant. Implant location, intertrochanteric and intercondylar, did not affect the data. In this minipig model, rougher surfaces showed better osseointegration. After 12 weeks of healing, the resorbable CaP layer enhanced significantly the bone‐implant contact but not the level of anchorage. The findings also suggest that the pull‐out test should be critically evaluated to determine the shear strength between bone and porous surfaces. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009