Abstract:

This paper presents the development of several 3D printed models of a lumbar spine segment for training nursing students on compression fractures and kyphoplasty repairs. The L1 vertebral body was segmented from a 3D printed model of a patient with no compression fracture. The segmentation occurred across the pedicles for only the L1 vertebra, leaving the 3D model of the lumbar spine segment intact. The lumbar spine model was created from a CT (computerized tomography) image and consequently was a high resolution image of the vertebrae. A second 3D printed model of a compression fracture at L1 was segmented from another model created from a MRI (magnetic resonance imaging) image. Also a third 3D printed model of the kyphoplasty repair at L1 from the same patient was segmented from another model of a MRI image. All the 3D models were printed on a MakerBot-Replicator+ using a PLA (polylactic acid) filament. The two L1 vertebrae were then scaled with the healthy L1 vertebra using 3Dbuilder software. The SLT files of the three L1 vertebrae were modified to include small holes to insert magnets. Likewise, two small holes were added to the STL file of the lumbar spine model at the pedicles where the vertebral body was segmented. All three L1 vertebrae where then 3D printed. Magnets were placed in the holes for snapping the various L1s into the lumbar spine model for training purposes. Intervertebral discs were added to the lumbar spine model. The discs were designed using CAD software and were 3D printed on a Prusa-i3 MK3S printer using a TPU (thermoplastic polyurethane) flexible filament. Silicone rubber O-ring cord, 10mm in diameter, was inserted into the spinal cavity to simulate the spinal cord and ran the full length of the lumbar spine model. Emerging from the spinal cord between the vertebrae were pairs of spinal nerves. Smaller, silicone rubber O-ring cords, 5mm in diameter and approximately three inches in length, were glued to the spinal cord with a special silicone rubber adhesive.

The 3D printed model of the lumbar spine segment were used to illustrate:
1) a healthy L1 vertebra,
2) a compression fracture by replacing the healthy L1 with the L1 compression fracture, and
3) a kyphoplasty repair by replacing the L1 compression fracture with the L1 kyphoplasty.

The College of Nursing at the University of Alabama in Huntsville has developed over one hundred simulation based learning experiences (SBLEs). Each simulated clinical experience is documented in detail and placed in a binder with specific objectives and a detailed set up sheet and pictures for standardized repetition with multiple clinical groups. The 3D printed models of the lumbar spine segment are currently being integrated into several of the SBLE training scenarios. Included in this paper are discussions of the 3D printed models; the compression fracture and kyphoplasty; the addition of intervertebral discs, spinal cord and spinal nerves for more realism; difficulties in scaling the L1 vertebrae from the three 3D models; the use of the models in training nursing students and conclusions.

Keywords:

3D Printed Training Models, Interchangeable 3D Printing, Kyphoplasty Models, Spinal Region.