Background: Evaluation of long-term outcomes of free-muscle transfer for smile restoration is overdue. Arguments for and against free-muscle transplantation in children are considered, and the debate on the influence of the growing skeleton on muscle function is revisited. This study evaluated the fate of free-muscle transfer over long follow-up periods in pediatric patients.
Methods: Thirty-two children with follow-up of 5 years or longer who received a free-muscle transfer for smile restoration were reviewed. To better analyze the effect of time, patients were classified into groups based on the length of follow-up: group A, 5 to 6 years; group B, 7 to 10 years; group C, 11 to 15 years; and group D, more than 15 years. Patients were videotaped at three stages: preoperatively, 2 years after free-muscle transfer, and at the last follow-up visit. Four independent observers graded patients' videotapes using a five-category scale ranging from poor to excellent. Panelists were asked to comment on any noticeable craniofacial disharmony with growth.
Results: All patients exhibited improved function and symmetry at 2 years after free-muscle transfer (averaged scores, p < 0.0001). A positive effect of time was seen in the long-term evaluation; observers' scores (p < 0.0001) and motor units on electromyography (p = 0.001) showed further improvement. No significance was found when comparing measured outcomes among the four follow-up groups, indicating that despite the growing skeleton, muscle function was maintained over time.
Conclusions: These clinical data support the use of free-muscle transfer for smile restoration in children. The transplanted muscle appears to grow harmoniously with the craniofacial skeleton, and muscle function and aesthetic outcomes improved over time.