Stress distribution on the thorax after the Nuss procedure for pectus excavatum results in different patterns between adult and child patients

Objective: In the Nuss procedure, in which the deformed thorax is forcibly corrected by insertion of correction bars, considerable stresses occur on the patient's thorax. We performed the present study to elucidate how stress patterns on the thorax after this procedure differ between child and adult patients. Methods: Eighteen patients with pectus excavatum, constituting a child group (n = 10) and an adult group (n = 8), were included in the study. After a 3-dimensional computer-assisted design model was produced with computed tomographic data from each patient, simulation of the Nuss procedure was performed on the model. Then the stresses occurring on each thorax were calculated using the finite element method. The stresses were compared between the child and adult groups in terms of intensity on each rib and the distribution patterns over the whole thorax. Results: With all 12 ribs, significantly greater stress occurred in the adult group than stress in the child group. Although the stresses occurring on the thorax demonstrated concentrated patterns in the child group, widely distributed patterns were observed in the adult group. Conclusions: The stresses that occur on the thorax after the Nuss procedure take different patterns between children and adults in terms of intensity and distribution. The differences should be taken into consideration in managing postoperative pain after the Nuss procedure.