Frontal ostium neo-osteogenesis and restenosis after modified endoscopic Lothrop procedure in an animal model.

All patients who undergo a modified endoscopic Lothrop procedure have postoperative narrowing of the enlarged frontal ostium. The aim of this study is to evaluate neo-osteogenesis and restenosis of the frontal ostium and its effect on mucociliary clearance. Fourteen sheep underwent an endoscopic modified Lothrop procedure. Pre- and postoperative nuclear medicine gamma scintigraphy of the frontal sinuses was performed. The sizes of the frontal ostia were measured and biopsies taken from the bone of the frontal ostium. Histological evidence of new bone formation was found in 56% of biopsies. The average preoperative mucociliary clearance half times (T1/2) at 15 and 30 min were 70 and 74 min, respectively, and postoperatively were 50 and 67 min. There was a non-significant trend towards poorer clearance in sinuses with neo-osteogenesis. The average size of the frontal ostium decreased by 28%. There was no relationship between the size of the ostium and neo-osteogenesis. Neo-osteogenesis was seen in 56% of biopsies with a 28% reduction in size of the frontal ostium after 224 days. Mucociliary clearance did not alter significantly.