AIM: To mathematically present the results of endoscopic assisted surgery in the treatment of metopic synostosis.

MATERIAL and METHODS: We present a follow-up of the stages of treatment of 43 patients with metopic synostosis who underwent surgery in a multicenter retrospective study between 2018 and 2021. We developed the formula D3/((D1+D2)/2) based on the theory of ?The Angle of a Triangle Opposite The Longest Side is the Largest Angle?. And we called this method ?Metopic Angle Proportion (MAP)?. Paired samples T-test was performed for statistical results. A p-value of <0.05 was considered statistically significant.

RESULTS: According to the MAP method; measurements for frontal enlargement, mean pretreatment length D1: 34,57 mm, D2: 34,81 mm, D3: 60,46 mm, and the end of treatment as D1: 37,88 mm, D2: 38,19 mm, D3: 71,09 mm. We perfomed the formula D3/ [(D1+D2)/2]. While this rate was 1.74 before treatment, it increased to 1.87 after treatment. As a result of statistical analysis, it was also found to be significant (p?0.05).

CONCLUSION: Endoscopy-assisted suturectomy can be applied in health centres where available, because it is safe, easy and cheaper.