Bone healing of tibial lengthening is delayed by cigarette smoking: Study of bone mineral density and torsional strength on rabbits

Objective: We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. Methods: Twelve male rabbits were divided into two groups of six animals each. The first group underwent intermittent cigarette smoke inhalation, and the second group did not undergo intermittent cigarette smoke inhalation. Each animal's right tibia was lengthened 5 mm by using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals 1 day before operation and 3, 4, 5, and 6 weeks after operation. All of the animals were killed 6 weeks postoperatively for biomechanical testing. Results: By using the preoperative BMD as an internal control, we found that the BMD of the smoke-inhalation group was decreased significantly compared with the non- smoke-inhalation group. The mean %BMD at 3, 4, 5, and 6 weeks were 49.9%, 61.2%, 65.9%, and 71.0%, respectively, in the smoke, inhalation group, whereas the mean %BMD were 54.9%, 71.8%, 76.4%, and 82.0%, respectively, in the non-smoke-inhalation group (two-tailed t test, p > 0.05, p < 0.01,p < 0.01 and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). By using the contralateral nonoperated tibia as internal control, we found that torsional strength of the smoke-inhalation group was decreased significantly compared with the non-smoke-inhalation group. The mean percentage of maximal torque was 63.8% in the smoke-inhalation group, whereas the mean percentage of maximal torque was 77.1% in the non-smoke-inhalation group (two tailed t test, p < 0.01). Conclusion: This study suggests that cigarette smoking delays the mineralization during the bone healing process of distraction osteogenesis and, thus, decreases the mechanical strength of the regenerating bone.