Transforming growth factor-6 stimulates bone ongrowth: Hydroxyapatite-coated implants studied in dogs

Abstract

Unloaded cylindrical grit-blasted titanium (Ti-6A-4V) implants (6×10 mm) coated with hydroxyapatite ceramic were inserted into the proximal part of the humerus of 20 skeletally mature Labrador dogs. The implants were initially surrounded by a 2 mm gap. In 10 dogs, HA-coated implants without growth factor were inserted in one humerus and implants with 0.3 ug rh.TGF-61 adsorbed onto the HA coating were inserted in the contralateral humerus. In another group of 10 dogs, a dose of 3.0 mg rhTGF-β1 was tested in a similar design. All dogs were killed at 6 weeks after treatment. Results were evaluated by histomorphometry and mechanical push-out testing. Bone ongrowth was increased by one third, using the 0.3 mg rhTQF-β1 stimulation. Bone volume in the gap and mechanical testing showed no statistically significant differences between control and rhTGF-β1 stimulated implants. RhTGF-β1 only moderately enhanced bone ongrowth to hydroxyapatite-coated implants.