The treatment of fracture accompanied with bone defect remains a challenge in skeletal surgery. For bone defect, we have to give a material to support healing process. Some material is allograft given at second to sixth weeks to avoid osteoclastic activity. We try to give primary allograft and to prevent osteoclastic activity we use risedronat. Risedronate (Actonel(r)) is one of bisphosphonate group that decrease the turnover of the bone by activating apoptosis of osteoclast and increasing osteoblast activity. The aim of this paper is to evaluate radiologically and histologically result for the effect of the bone healing process for a fracture associated with bone defect which treated by a combination of fresh frozen allograft and risedronate (Actonel(r)).

The design is an experimental study, Post Test Only Control Group Design, using adult male white rats spraque-dawley. Right open tibial osteotomies to create bone defect are performed surgically and put Kirschner wire as intramedularry fixation. Rats are divided into four groups, with six samples in each group. Group one with bone defect in 2 mm, group two with bone defect 2 mm and put fresh frozen allograft, group three with bone defect 2 mm and put fresh frozen allograft and given Actonel(r) 350g a week for two first week, and group four with bone defect 2 mm and put fresh frozen allograft and given Actonel(r) 350g a week for six week. Six weeks after implantation, the animals were sacrificed, and the tibia were evaluated by radiological and histological studies.

Radiologically, there are significant different of relative bone healing result between ungiven risedronat group (group one and two) and given risedronat group (group three and four) (Kolmogorof smirnov test). Histological results by one way anova shows varians test was p = 0,168 (p > 0,05). Anova test was p = 0,000 (p < 0,05), post hoc Turkey HSD there was not significant different between group one and group two p = 0,969, between group one dan group four p = 0,634 (p > 0,05), between group two dan group four p = 0,634 (p > 0,05); a significant different between group one and group three p = p = 0,000 (p<0,05) between group two and group three p = 0,01 (p < 0,05), and group three and group four p=0,004 (p < 0,05)

Risedronate (Actonel(r)) influence the healing process of two mm bone defect radiologically. By histologically, two first weeks given of risedronate at group three have a better result than groups one, two and four.