Efeito do número de sessões de oxigenoterapia hiperbárica na biomecânica e reparação de tecido ósseo irradiado ou não irradiado em ratos

Abstract

Hyperbaric oxygen therapy (HBO) aims to minimize the risks of osteoradionecrosis (ORN) and to obtain success in surgical procedures involving manipulation of previously irradiated bone. However, HBO application protocols are not well-defined yet, and studies determining the ideal number of sessions have not been carried out to date. This work aimed to investigate the effect of HBO on tissue healing, correlating it to particular numbers of sessions. A total of 40 clinically healthy male Wistar rats, weighing between 250 and 350 g had their left legs irradiated with a single dose of 30 Gy. After 30 days, they were submitted to surgery to create a bone defect, immediately following HBO, using the variables of 0, 10, 20, 30 and 40 sessions, over 90 minutes per day, under 2.5 ATA. The animals were sacrificed and their tibiae submitted to a three point bio-mechanic test assay to calculate maximum strength (N), work to failure (mJ) and stiffness (N / mm). In addition, micro-CT was performed to analyze bone defects in the femur regarding: (1) bone volume percentage (BV / TV); (2) connectivity density (Conn. D); (3) Trabecular separation (Tb. Sp ); (4) Trabecular thickness (Tb. Th); (5) Trabeculae number (Tb.N). The three point test showed differences between the groups (I x NI) for 0 (p = 0.006), 10 (p = 0.049), 20 (p = 0.027), and 40 sessions (p = 0.047). Significant differences in trabecular separation were found among the various parameters evaluated in the micro-CT, when 0 and 20 sessions were compared (p<0.05). HBO favored bone tissue rigidity after radiotherapy and the number of HBO sessions performed did not influence the bone tissue healing process in rats.