Achmad Kamal - Department of Orthopaedic and Traumatology, Cipto Mangunkusumo National General Hospital, Faculty of Medicine Universitas Indonesia, Jakarta, Indonesia
Othdeh Samuel Halomoan Siahaan - Department of Orthopaedic and Traumatology, Cipto Mangunkusumo National General Hospital, Faculty of Medicine Universitas Indonesia, Jakarta, Indonesia
Jessica Fiolin - Department of Orthopaedic and Traumatology, Cipto Mangunkusumo National General Hospital, Faculty of Medicine Universitas Indonesia, Jakarta, Indonesia

Background: BMP-2 has a crucial role in the treatment of extensive bone defect. However, data about the optimaldosage of BMP-2 in the massive bone defect casesis rare.Methods: Twenty-five SD rats were randomly allocated into a control group of hydroxyapatite (HA) alone (Group I),HA+BMP-2 1μg/mL (Group II), HA+BMP-2 5 ug/mL (Group III), HA+BMP-2 10 μg/mL (Group IV), and HA+BMP-2 20ug/mL (Group V). Osteotomies were performed in each group with 10 mm bone defect in the right femur, followed byfixation and filling the defect. The fracture healing was evaluated by histomorphometry, and radiographs using RUSTscore.Results: We found there were significant differences in the mean total area of callus between the treatment groups(P<0.001); there were significant differences in the mean area of woven bone between group II, III, IV, and V with thecontrol group (respectively P=0.009, P=0.016, P=0.009 and P=0.016), the area of the cartilage between the treatmentgroups and control group (respectively P=0.009, P=0.009, P=0.009 and P=0.028). A statistically significant differencewas found in the average area of fibrosis between group II and control group, group IV and control group (respectivelyP=0.047 and P=0.009). RUST scores showed significant differences between the control group and group II, III, IV, V(respectively P=0.005, P=0.006, P=0.005 and P=0.006).Conclusion: The administration of BMP-2 stimulates the formation of bone bridging in a massive bone defect. Thebone bridging filling massive bone defect depends on the dose or concentration of BMP-2. Administration of an optimaldose (10 μg/mL) of BMP-2 demonstrates better result than lower or higher dose for massive bone defect healing in SDrate.Level of evidence: II

BMP-2, Fracture healing, massive bone defect, optimum dose