Novel index to estimate the cephalocaudal extent of the excavation in pectus excavatum: The Titanic index

Abstract

Quantification of the severity of pectus excavatum deformities is currently performed using the Haller index (HI) and the Correction index (CI), amongst others. However, most indexes characterize the severity at the point of maximum excavation. We present a new index, the Titanic index (TI), aimed at the appraisal of the cephalocaudal extent of the excavation and its potential clinical use. Retrospective analysis of a cohort of patients who underwent a minimally invasive repair of pectus excavatum (MIRPE) between July 2020 and April 2022at a single center. We defined TI as the percentage of the sternum that lied behind the anterior costal line observed in the CT. Demographics, HI, CI, and TI calculated based on computed tomography images (CT) were analyzed. Also, we compared the severity indexes of two groups of patients divided by the number of implants introduced per patient (group A: two implants, and group B: more than two). Seventy-eight patients (92% male) were included, with a mean age of 17.2±4.8 years. The mean TI was 37%. Albeit weak, we identified significant correlations between the TI and the HI and, more closely, to the CI. Two implants were introduced in 37 (47%) patients, and more than two in 41 (53%) patients. Compared to patients with two implants, the group of patients who received more than two implants were older and showed worse thoracic indexes. Using receiver operating characteristic curve analysis, we identified the TI as a better predictor of the need for more than two implants than HI and CI. In this regard, a TI larger than 66.5% had a sensitivity of 93% and a specificity of 92%. We propose a novel index for the categorization of the severity of pectus excavatum. This index might be useful in planning the number of implants required for complete thoracic remodeling during MIRPE. Level III. Retrospective Comparative Study.