This depends on what facility you have at your University. You need only six weeks of healing if it is done in the femur or tibia. If you are using the resin embedded technique for histology it will cost you around 300 EURO per specimen. Micro CT will be around 100 EURO per specimen. You are planning in 7 rabbits (7x2X2 =28 specimens). Placing it in tibia and femur on each side may be risky. It can end up in fracture. However, it depends on the defect size. Please see the following publications.