The metopic angle: a novel assessment tool of the trigonocephalic frontal deformity and its correction

While metopic synostosis is typically a straightforward clinical diagnosis, there is no standard objective measurement that can be easily used in the preoperative evaluation and in the subsequent postoperative follow-up. Despite the fact that multiple methods have been previously described, they either lack well-defined landmark points, do not specifically address the frontal vault deformity, or are too cumbersome to be used routinely for clinical applications. We describe the metopic angle as an objective and dependable method for evaluation of the frontal vault contour.Using the STARscanner Laser Data Acquisition System, a portable, noninvasive diagnostic modality, the metopic angle was defined. This angle was used to track postoperative changes and was compared with preoperative values in patients who underwent minimally invasive strip craniectomy for metopic synostosis. To further ensure its validity, the angle was also measured in age-matched control subjects.The metopic angle changed from a preoperative value of 104.9 degrees to 111.3 degrees at 3 months (P = 1.59E-06) and to 114.9 at 1 year postoperatively (P = 2.51E-09) in patients who underwent endoscopic-assisted strip craniectomies for metopic synostosis. The resulting postoperative values were comparable to those obtained in age-matched control subjects with normal cranial vaults.The metopic angle measurement is a rapid, noninvasive, reproducible method for objective measurement of both preoperative deformity and postoperative correction of the frontal bone contour in metopic synostosis.