Modeling of the chest wall response to prolonged bracing in pectus carinatum.

Pectus carinatum is a chest wall deformity that is often treated through the wearing of an external brace. The treatment of the deformity could benefit from a greater understanding of chest wall characteristics under prolonged loading. These characteristics are difficult to model directly but empirical studies can be used to create statistical models. 185 patients from 2018-2020 received bracing treatment. Data on the severity of the deformity, treatment pressures, and time of wear were recorded at the first fitting and all subsequent follow-up visits. This data was analyzed using a statistical mixed effects model to identify significant measures and trends in treatment. These models were designed to help quantify changes in chest wall characteristics through prolonged bracing. Two statistical models were created. The first model predicts the change in the amount of pressure to correct the deformity after bracing for a given time and pressure. The second model predicts the change in pressure response by the body on the brace after bracing for a given time and pressure. These models show a high significance in the amount of pressure and time to the changes in the chest wall response. Initial deformity severity is also significant in changes to the deformity. The statistical models predict general trends in pectus carinatum brace treatment and can assist in creating treatment plans, motivating patient compliance, and can inform the design of future treatment systems.

An Aggregate Sternal Force-Deflection Model.

Understanding the force-deflection behavior of the sternum is an important element in designing devices for implants for chest wall deformity repair. Human growth and variability makes a single measure of the stiffness difficult to determine. This work takes empirical data from the literature to develop aggregate sternal force-deflection models. Statistical methods were used to determine possible groupings based on patient age and the effect of gender. It was found that three age groups could be used, representing childhood (4-10 years), adolescence (11-19 years), and adulthood (26-53 years). Gender was found to have a statistical p-value of 0.068, 0.0611, and 0.012, respectively, in the proposed age groups. Jittering of the data was used to account for human variability and assumptions made in data comparisons. The jittered results followed that of the initial dataset. Childhood force-deflection behavior follows a relatively constant stiffness, adolescence experiences a growth period of increasing stiffness, and adulthood stiffnesses again begin to stabilize around a relatively constant value.