(Poster 49) 3D Modeling of the Cadaveric Sacrum and Coccyx: A Feasibility Study

Objectives: 3-dimensional (3D) scanning and printing allows for the creation of 3D objects from digital files. It has been utilized in cardiothoracic and orthopedic surgery to create patient-specific anatomic models for presurgical planning, typically by using a patient’s medical imaging files. The utility of this technology has not been well established in the field of Urogynecology; however, it may be useful for training and surgical planning in sacral neuromodulation where anatomic variation from sacrococcygeal trauma or injury is suspected. This study aimed to examine the feasibility of reproducing reliable 3D sacral models from cadavers for future educational training.

Methods: Ten fresh-frozen female cadavers from the University of Louisville Willed Body Program were available for sacral dissection. An extensive dissection was performed starting at the level of the posterior superior iliac spine to the level of the coccyx, revealing all bony landmarks and foramina of the sacrum. The CR-Scan Lizard (Creality ®) portable 3D scanner was used to scan each sacrum and coccyx. The CR Studio program (Creality ®) was used to edit the scan’s output and convert it to a template for the solid model. A resin model was printed for each of the ten cadaveric sacrums with 5 mm holes to represent S1-S4 foramina. After dissection and scanning, numerous measurements were obtained on the cadaver and each associated model, including length and width of the coccyx, inferior tip of the coccyx (TC) to bilateral S3 and S4 foramina, Sacrococcygeal (SC) joint to bilateral S3 and S4 foramina, and inter-foraminal distance (Figure 1). The accuracy of the 3D printed models was computed using the concordance correlation coefficient between cadaver and 3D model measurements (Table 1). Concordance correlation coefficient values close to one indicate consistently similar results, while values closer to zero indicate no relationship.

Results: Figure 1 exhibits the 3D-printed resin sacral cadaver model. Corresponding bony landmarks and distances are represented by the demarcated lines. The accuracy of the 3D-printed cadaveric models was high with concordance correlation coefficients ranging from 0.61-0.95 (Table 1). Concordance was highest with bilateral SC joint to S3 foramen and lowest with inter-foramen S3 distance. Lower concordance with inter-foramen distance was thought to be related to the post-processing of foramen holes. All 3D scanned cadavers were successfully printed into their corresponding models.

Conclusions: This study demonstrates the feasibility of using a portable 3D scanner to develop reliable 3D-printed cadaveric sacral models. Models were reproduced with high concordance to all cadaver bony landmark measurements and reliably demonstrated the complex geometry of the sacrum and coccyx. Further work needs to be done to determine the potential for 3D scanning and modeling for both pre-surgical planning and training for sacral neuromodulation procedures.

Legend:
S1-S4= Sacral nerve foramen, SC=sacrococcygeal, TC= tip of coccyx