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 clinical correlate. Recent experimental work has suggested that increased lip pressure following an undermined lip repair may contribute to midfacial growth inhibition. Soft-tissue expansion has been used to generate 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 midfacial growth. To test this hypothesis, 40 4-week-old rabbits were randomly divided into four groups. Two groups had surgically created lip and alveolar defects. Ipsilateral labial tissue expanders were placed in all four groups. One cleft and one normal group underwent expansion. The other two groups served as a control. The expanders were removed at 4 weeks, and an undermined lip repair was performed in both cleft groups. Findings revealed that soft-tissue expansion increased labial surface area significantly by approximately 96% (p < 0.001). Labial soft-tissue expansion alone had no effect on midfacial growth during the observation period. In contrast, cleft animals undergoing tissue expansion exhibited significantly reduced (p < 0.05) postoperative lip pressure and increased midfacial growth compared with cleft animals without expansion through 36 weeks of age. Results suggest that preoperative tissue expansion reduced postoperative lip pressure and improved midfacial growth in a rabbit cleft lip model.