Computer imaging assists with facial reconstructive surgery

A new calibration technique that involves measuring the distance between the upper ear and chin in photographs could help facial plastic surgeons use computer imaging software to achieve aesthetic harmony in their patients, according to a report in the March/April issue of Archives of Facial Plastic Surgery, one of the JAMA/Archives journals.

“The importance of balanced facial proportions has been studied for centuries by architects, artists, physicians and dentists,” the authors write as background information in the article. It is essential for plastic surgeons to accurately analyze the face before surgery so that afterward, prominent facial features such as the chin and nose are balanced in relation to the structures around them. “Even a well-executed surgery will result in a poor aesthetic result if inaccurate analysis leads to an improper decision (e.g., an excessively large chin implant).”

Travis T. Tollefson, M.D., and Jonathan M. Sykes, M.D., of the University of California, Davis, Medical Center, Sacramento performed a photograph analysis and medical record review of 14 patients (average age 32, 12 females and two males) who underwent combined rhinoplasty (nose surgery) and chin correction at an academic medical center between 1999 and 2004. Six of the patients received implants in their chins, while eight underwent a procedure known as osseous genioplasty, involving surgery on the chin bone. Preoperative and postoperative photographs were analyzed and the distance from the porion (the top of the external ear canal) to the pupil and to the pogonion (the most prominent point on the chin) was measured. These measurements were used to develop a standard scale so that patients’ before and after photographs could be compared, even if they were not the same size.

Additionally, the following established measures were analyzed:

• Cervicomental angle: the intersection of a line drawn next to the neck and a line drawn from the bottom of the chin through the point where the neck and the jaw connect
• Mentocervical angle: the intersection of a line drawn from the tip of the nose to the chin and a line drawn next to the neck
• Facial convexity angle: the intersection of a line drawn from the forehand to the chin and a line drawn from the bottom of the nose to the chin

In all patients, the porion to pogonion distance and the ratio of the distance between the pupil and the pogonion and the distance between the porion and the pogonion increased, the cervicomental angle decreased, the mentocervical angle decreased and the facial convexity angle increased after surgery. These changes brought the patients closer to the normal range for these measurements and angles.

“Surgery for facial disharmony requires artistic judgment and objective evaluation,” the authors conclude. “For surgeons who use computer imaging software, analysis of profile photographs is the most valuable tool. Even when preoperative and postoperative photographs are of different sizes, relative distance comparisons are possible with a new calibration technique using the constant facial landmarks, the porion and the pupil. The porion-pogonion distance is a simple reproducible measurement that can be used along with established soft tissue measurements as a guide for profile facial analysis.” Source : JAMA and Archives Journals