Development and clinical usage of a motion analysis system for the face: preliminary report.

Objective: To evaluate the motion of the face and jaw of patients with cleft lip and palate, facial palsy, and in patients after reconstruction, a motion-analyzing system was developed. The aim of this article was to investigate the accuracy of this system and the possibility of clinical application.

Methods: Markers of 1 to 2 mm were placed on the face, and motion images were obtained by three digital video cameras controlled by a synchronizer and recorded on digital video tape. The image was processed on a personal computer. The markers were automatically tracked across the image sequences, and their three-dimensional coordinates were then calculated.

Main Outcome Measures: System accuracy was investigated using a positioning actuator with high accuracy and a known object. In three patients with bilateral cleft lip and palate, lip pursing was analyzed using the aforesaid method.

Results And Conclusions: The mean differences from the known values to the distances between the tracked sample points and to the mobile distances of the sample points per frame were 0.24 to 0.36 mm and 0.02 to 0.05 mm, respectively. Both results were similar regardless of the mobile speed or direction. In five repeated measurements, the mean differences from the known values as for the distances and the mobile speed ranged from 0.19 to 0.38 mm and from 0.00 to 0.07 mm, respectively. Examination of three patients with bilateral cleft lip and palate indicated the possibility that lip movement could be successfully analyzed using the present system.