Push-out strength of hydroxyapatite coated by sputtering technique in bone.

Hydroxyapatite was coated with 1 microm thickness on titanium columns of a length of 10 mm, an outer diameter of 4.0 mm by radio frequency magnetron sputtering. The hydroxyapatite coating titanium columns were implanted in the diaphysis of femora of 3 adult dogs, and push-out test was carried out after 2, 4 and 12 weeks of implantation using a testing machine. The interface of bone/column was observed histologically after the test. At 12 weeks the push-out strengths of coating and non-coating columns were 3.5 and 1 MPa, respectively. Histological observation indicated a formation of thin connective tissue with 5-30 microm thickness at the interface of the bone/column. No inflammation was observed during the implantation periods.