Date of Award

Summer 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mathematics and Statistics

Program/Concentration

Mechanical Engineering

Committee Director

Stephen B. Knisley

Committee Member

Gene J.-W. Hou

Committee Member

Frederic D. McKenzie

Call Number for Print

Special Collections; LD4331.E56 N55 2012

Abstract

Pectus excavatum (PE) also known as sunken or funnel chest is the most common chest wall deformity and affects 1 in every 1,000 children. In PE patients, the middle lower portion of the sternum is depressed producing concave appearance of the anterior part of the chest wall. This problem can be corrected with minimally invasive surgery developed by Dr. Donald Nuss in 1986. A specially made steel bar is implanted to lift the sternum to its normal position. This technique has been modified several times to improve safety and effectiveness of the bar placement and removal. One of the significant aspects of the procedure is the pre-bending of the bar to the patient's desired chest shape. This is because, sometimes, the bar will slightly straighten after implantation due to force from the sternum, thus altering the bar shape. This can cause the ends of the bar to protrude noticeably out of the chest, thus requiring the surgeon to remove the bar and reshape with an additional curvature (hyper-bending). The goal of this study is to provide a quantitative prediction of the amount of hyper-bending needed to produce optimal bar shape after bar implantation. To accomplish this, Pectus bar 3-D models were developed for different age groups using Pro/Engineer modeling software. Pectus bars were analyzed by conducting a linear static finite element analysis (PEA) on different patient specific bar models to find out bar end displacements in horizontal and vertical direction. Validation of the final displacement results were conducted by performing experiments on the Pectus bar obtained from the bar manufacturer. The results derived from this study can be used by the surgeons to predict suitable amount of hyper-bending. With the help of this study surgeons may eliminate the need to remove and implant the bar, thus shortening surgery time. These findings also demonstrate relationship between sternum force and bar end displacement for different age group PE patients.

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DOI

10.25777/32rt-6856

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