Effects of a dexamethasone-releasing stent on osteoneogenesis in a rabbit model.

BACKGROUND: This study is an evaluation of wound healing in an animal model for surgery of frontal sinusitis and treatment effect of topically released dexamethasone using a drug-releasing stent with special emphasis of osteoneogenesis. METHODS: A prospective, controlled, randomized, double-blinded animal study was performed. Nineteen New Zealand white rabbits were subjected to surgery via an external approach, a 4-mm circular wound was created on the medial side of the maxillary sinus and the underlying bone was denuded of periosteum. The wound was covered in a randomized fashion with either a silicone foil or a new dexamethasone-releasing stent system. Twelve to 30 days later, the animals were killed and a histological examination was performed. RESULTS: In comparison with the baseline bony thickness (40 micrometer) obtained in one animal, osteoneogenesis occurred on both paranasal sides but was significantly less if a dexamethasone-releasing stent was applied (117 [95% CI, 116-128]; 52 [95% CI, 43-64]; p < 0.001). Maximal bony thickness was observed in both treatment groups between days 20 and 25 with a tendency toward a higher percentage decrease in the dexamethasone-treated sides (p < 0.08). Using a visual analog scale (0-5) a significantly smoother bony surface was observed for dexamethasone (2 [95% CI, 1.1-1.9]; 2 [95% CI, 1.8-2.2]; p < 0.01). CONCLUSION: Using a new drug-releasing stent system, dexamethasone efficiently decreases postoperative osteoneogenesis in a standardized animal wound model for endoscopic sinus surgery. Therefore, the use of this system may be of value to decrease restenosis rates using corticosteroids in selected patients after frontal sinus surgery, especially the endoscopic modified Lothrop procedure.

Effects of topically applied dexamethasone on mucosal wound healing using a drug-releasing stent.

OBJECTIVE/HYPOTHESIS: Evaluation of the impact of continuously topically released dexamethasone using a drug-releasing stent on quality of regenerated mucosa after full thickness injury in the paranasal sinuses. STUDY DESIGN: Prospective, controlled, randomized, double-blinded animal study. METHODS: Nineteen New Zealand white rabbits were subjected to surgery: via an external approach, a 4 mm circular wound was created on the medial side of the maxillary sinus. The wound was covered in a randomized fashion with either a silicone foil or a new drug releasing stent system. Twelve to 30 days later, the animals were killed and histology and electron microscopy were performed. One animal was used for baseline comparisons at day 0. RESULTS: No animals were lost due to infection or dislocation of the stent, leaving 18 animals for evaluation of postoperative healing quality. According to macroscopic examination, extent of granulations was smaller in the treatment group (dexamethasone: median 0 [95% confidence interval: 0.1-0.6]) than the silicone group (2 [1.5-2.3]; P < or = .05). Epithelial wound healing was complete in all specimens, whereas the stroma was significantly thinner in the dexamethasone-group (44 [37-60]; 178 [148-214]). Improved healing quality was achieved significantly more often on the treatment, than on the control side. Scanning electron microscopy revealed no difference between both groups. CONCLUSIONS: Using a new drug-releasing stent system, dexamethasone efficiently decreases granulation formation and stroma thickness without impeding epithelial differentiation. Therefore, the use of this system may be of value to decrease restenosis rates in selected patients after frontal sinus surgery.