The Effect of Strontium Ranelate on Fracture Healing: An Animal Study

Abstract

Background. Strontium ranelate (StR) is an antiosteoporotic agent previously utilized for the enhancement of fracture union. We investigated the effects of StR on fracture healing using a rabbit model. Methods. Forty adult female rabbits were included in the study and were divided in 2 equal groups, according to StR treatment or untreated controls. All animals were subjected to osteotomy of the ulna, while the contralateral ulna remained intact and served as a control for the biomechanical assessment of fracture healing. Animals in the study group received 600 mg/kg/day of StR orally. All animals received ordinary food. At 2 and 4 weeks, all animals were euthanatized and the osteotomy sites were evaluated for healing through radiological, biomechanical, and histopathological studies. Results. The treatment group presented statistically significant higher callus diameter, total callus area, percentage of fibrous tissue ( $p<0.001$ ), vessels/mm2, number of total vessels, and lower osteoclast number/mm2 ( $p<0.05$ ) than the control group at 2 weeks. Additionally, the treatment group presented significantly higher percentages of new trabecular bone, vessels/mm2, osteoclast number/mm2, and lower values for callus diameter, as well as total callus area ( $p<0.05$ ), than the control group at 4 weeks. At 4 weeks, in the treatment group, force applied ( $p=0.003$ ), energy at failure ( $p=0.004$ ), and load at failure ( $p=0.003$ ) were all significantly higher in the forearm specimens with the osteotomized ulnae compared to those without. Radiological bone union was demonstrated for animals receiving StR at 4 weeks compared with controls ( $p=0.045$ ). Conclusion. StR appears to enhance fracture healing but further studies are warranted in order to better elucidate the mechanisms and benefits of StR treatment.