The injury was sutured with absorbable material after the implantation. Antibiotics and anti-inflammatory agents were delivered in the postoperative period to prevent infection and pain. Rabbits were sacrificed after 15 and 30 days of implantation by intravenous injection of 0.4 mg sodium pentobarbital (Dolethal®, Vetoquinol, Cedex, Francia) diluted in serum (Fig. 1).

Tibiae were cleaned from soft tissues to determine the bone mineral density (BMD). Densitometries at 0.5 mm above and 0.5 mm below the Ti6Al4V implant were acquired to compare the BMD of control and OVX groups.

Histological study of each tibia (including the Ti6Al4V implant) for control and modified implants and with and without GH was carried out. Clean hard tissues were fixed in 10 % pH 7 buffered formaldehyde and dehydrated in grading alcohol concentrations. Tibiae were cut into blocks and histologically prepared according to the modified Donath and Breuner method. The preparation of hard tissue consisted of embedding in light-polymerizing 2-hydroxietyl-metacrylate. These blocks were cutting in five sections of about 200 μm and then grinding until achieving cross-sections of about 80-μm final thicknesses with an EXAKT cutting and grinding equipment (EXAKT, Norderstedt, Germany).

Bone-implant interface sections were examined under the optical microscope (Zeiss, Oberkpchen, Germany) using histological laboratory stains such as toluidine blue with Weigert haematoxylin (Merck, Kenilworth, NJ, USA) that allows the differentiation between osteoblasts and osteoclasts.

The images were processed and cross-sections were compared by means of the MIP-4 image analyser software (Digital Image Systems, SL, Barcelona) in order to quantify the bone fraction. The MIP-4 software is able to perform area and volume measurements through a computerized system connected to the optical microscope and histological lens. Area and length measurements on the images captured from the microscope were attained. All images were processed with ×10 magnification objective. The bone-to-implant contact (BIC) is calculated as the ratio of the length of the implant in contact to bone tissue and the implant perimeter, i.e. the percentage of the implant surface in contact with bone.