Force balance reconstruction of the orbicularis oris in unilateral incomplete cleft lip

Purpose To demonstrate a maneuver for achieving optimal force balance of reconstructed orbicularis oris during primary unilateral incomplete cleft lip reconstruction. Methods The surgical maneuver was performed as follows: the length of the orbicularis oris on the noncleft side is first isolated and adjusted to be equal to the length of the muscle on the cleft side. The remaining muscle from the noncleft side near the midline is used to fill in the vermilion tubercle, and finally, the two orbicularis oris muscles are sutured at the midline. Finite element analysis was utilized to model the biomechanics of our novel surgical method. Results Finite element analysis showed that when the lengths of two orbicularis oris muscles were the same after primary cleft lip repair, the stress on this muscle system was minimized under different lip conformations. Seventeen cleft lip patients were enrolled to receive reconstruction with this new maneuver. Significant differences were found in (1) noncleft/cleft alar base width, nasal dorsum angle, columella length relationship between two sides, and columella angle under the comparison between preoperative and postoperative; (2) noncleft/cleft alar base width, nasal dorsum angle, and columella angle under the comparison between preoperative and follow-up; and (3) columella length relationship between two sides under the comparison between postoperative and follow-up. Conclusion Force balance of the orbicularis oris muscles is important during unilateral incomplete cleft lip repair. This surgical maneuver for achieving force balance of the orbicularis oris and the muscle system of the lips is easy to perform and can help avoid relapses.