THE EFFECTS OF SOFT-TISSUE EXPANSION ON LIP REPAIR AND MIDFACIAL GROWTH IN A RABBIT CLEFT-LIP MODEL

Midfacial hypoplasia following primary cleft lip repair is a common cl inical correlate. Recent experimental work has suggested that increase d lip pressure following an undermined lip repair may contribute to mi dfacial growth inhibition. Soft-tissue expansion has been used to gene rate additional soft tissue for reconstruction in the cranial region. The use of this technique in the labial region may allow lip repair to be performed with less tension (pressure) and thus facilitate midfaci al growth. To test this hypothesis, 40 4-week-old rabbits were randoml y divided into four groups. Two groups had surgically created lip and alveolar defects, Ipsilateral labial tissue expanders were placed in a ll four groups. One cleft and one normal group underwent expansion. Th e other two groups served as a control. The expanders were removed at 4 weeks, and an undermined lip repair was performed in both cleft grou ps. Findings revealed that soft-tissue expansion increased labial surf ace area significantly by approximately 96% (p < 0.001). Labial soft-t issue expansion alone had no effect on midfacial growth during the obs ervation period. In contrast, cleft animals undergoing tissue expansio n exhibited significantly reduced (p < 0.05) postoperative lip pressur e and increased midfacial growth compared with cleft animals without e xpansion through 36 weeks of age. Results suggest that preoperative ti ssue expansion reduced postoperative lip pressure and improved midfaci al growth in a rabbit cleft lip model.