Iloprost inhibits fracture repair in rats

BACKGROUND: Previous studies have shown that prostaglandins (PGs) dramatically stimulate healing processes in bone. However, the effect of prostaglandin I2 (PGI2) on fracture healing remains unclear. To investigate the effect of PGI2, a study on fracture healing process in closed tibia fractures was designed. METHODS: Thirty-six Sprague-Dawley male rats were randomized into two groups. On the first day, their right tibias were fractured by three-point bending technique. The study group (n = 18) received a single injection of 10 µg/kg iloprost for 5 days, while the control group (n = 18) received saline solution in the same way. On the 7th, 14th and 28th days following the fracture, six rats were sacrificed and their right legs were harvested in each group. The progression of fracture healing was assessed for each specimen by the scores of radiography (by Lane-Sandhu) and histology (by Huo et al). RESULTS: On the 7th day, the radiographic and histologic scores were equal. On the 14th day radiographic total score was 6 and histologic total score was 23 in the iloprost group, whereas radiographic total score was 11 and histologic total score was 33 in the control group. On the 14th day radiographic and histologic scores were significantly decreased in the iloprost group compared to the control group (P < 0.05). On the 28th day radiographic total score was 12 and histologic total score was 37 in the iloprost group, whereas radiographic total score was 15 and histologic total score was 40 in the control group. On the 28th day although there was a decrease in radiographic and histologic scores of the iloprost group acording to control group, it was not statistically significant (P > 0.05). CONCLUSION: Iloprost delays fracture healing in early stage in rats.