SUNConferences, 17th Annual Conference of the Rapid Product Development Association of South Africa

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3D digital sculpting for the reconstruction of Poland’s syndrome deformities
Izél Van Heerden, Annabel Fossey, Gerrie Jacobus Booysen

Last modified: 2016-10-21

Abstract


Poland’s syndrome is a unilateral congenital defect displaying deformities of mostly soft tissues and the skeleton. The syndrome commonly affects the right side of the thorax and is more often found in males. Poland’s syndrome patients often display the absence of the pectoralis major muscle, although other muscles may also be affected. These patients usually seek medical intervention to improve their aesthetic appearance. Most interventions are traumatic, invasive, surgical procedures. Less invasive and traumatic approaches are advantageous. Design and manufacturing technologies makes it possible to produce custom-made implants for these patients. Therefore, the aim of this study was to design 3D digital geometries of missing pectoralis major muscles for two case studies; female and male; each differing in severity of the deformities on the right side of the thorax. Computed tomography data were acquired and processed in Mimics®. Processing entailed producing STL files of the segmented pectoralis muscles and the entire thoraxes. For each case study the thorax was imported into Geomagic® Freeform®, which acted as a receiving digital matrix of the segmented pectoralis muscle. The pectoralis muscles were fitted in their original positions in the receiving matrix. Because of the bilateral anatomy of a human body, the pectoralis muscle could be mirrored into the deformed side of the matrix. This was accomplished by activating coordinate planes; aligning the matrix at the shoulders; and drawing boundary curves on the left side. Thereafter, the boundary curves and muscle were mirrored to the deformed right side. Because of additional skeletal deformities the segmented mirrored muscles did not fit accurately in both cases and thus required additional sculpting manipulation. The sculpting process improved the fitting of the segmented muscles substantially, demonstrated by deviation analyses. Deviations between the healthy side and reconstructed side of the thoraxes were calculated and found that for the female 78% of the test points fell in the nominated tolerance region of >-5 and <+5 mm, and for the male 88%. During the sculpting process, the female’s muscle was enlarged from the original segmented muscle with surface area of 34.52 × 103 mm2 and volume of 16.84 × 104 mm3 to 42.11 × 103 mm2 and 19.51 × 104 mm3. Sculpting of the male’s muscle was less from a surface area of 50.28 × 103 mm2 and volume of 34.85 × 104 mm3 to 53.63 × 103 mm2 and 36.22 × 104 mm3.


Keywords


medical modelling; computer-aided design; medical imaging technology; Poland’s syndrome; Geomagic® Freeform®