1. Final Presentation Patrick Melton Daniel Escobar 4/26/11

2. Hindfoot Anatomy

3. Purpose Create a device that will apply stress to the subtalar joint for the best possible radiographic images to allow for accurate measurements and determine the stability of the joint.

4. Cobey View Reilingh, M., Beimers, L., Tuijthof, G., Stufkens, S., Maas, M., & van Dijk, C. (2010). Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiology, 39(11), 1103-1108.

5. Long Axial Alignment View Reilingh, M., Beimers, L., Tuijthof, G., Stufkens, S., Maas, M., & van Dijk, C. (2010). Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiology, 39(11), 1103-1108.

6. Semester Recap Research Phase Literature Review Similar devices EndNote Design Phase Modeling/Drawings Size Calculations Analysis Phase Finite Element Analysis Optimization Completed Tasks

7. Final Design  30 degree plate inclination with additional forefoot plate that rotates 15 degrees.  Sliding heelcup plate for various foot sizes.  Allows for footstraps to be placed in multiple areas.

8. Final Design  Utilizes two bolts that act as columns to angulate the foot for optimal positioning of the subtalar joint.

9. Dimensions - Bolts Ø 1.125” UNF – 12 Hex Head bolt 15° Ø 0.5” UNF – 20 Hex Head bolt

10. Dimensions - Hinges Shoulder screw - Ø ½”, 3/8”–16 thread with matching nut. Shoulder screw – Ø ¼” #10–24 thread with matching nut. Hinge: Ø 1.0” Outer Ø 0.5” Inner Hinge: Ø 0.5” Outer Ø 0.25” Inner

11. Finite Element Analysis – Foot Plate  Max Displacement:.0618 in.

12. Finite Element Analysis – Foot Plate  Max Stress: 2550 psi  Safety Factor: 3.92

13. Finite Element Analysis – Base Plate  Max Displacement:.0362 in.

14. Finite Element Analysis – Base Plate  Max Stress: 1180 psi  Safety Factor: n = 8.47

15. Finite Element Analysis – Forefoot Plate  Max Displacement:.0273 in.

16. Finite Element Analysis – Forefoot Plate  Max Stress: 8970 psi  Safety Factor: n = 1.12

17. Materials Selection Most of the device will be made from a radiolucent plastic called Delrin, manufactured by DuPont. Tensile strength – 400 ksi Yield Strength – 10 ksi Density – 1.42 g/cm 3 Footstraps made from Nylon Foam padding (Lux-R-Foam) on sliding plate, forefoot plate, and in heelcup.

18. Cost MaterialsDimensionsCost Delrin Sheets (4)12" x 24" x 1"$159 ea. Delrin Rods1 ¼" D$7.50/ft. ½" D$1.56/ft.* ¼" D$0.52/ft.** Lux-R Foam Padding82" x 36" x ¼"$5.99 Velcro Straps (4)1" W x 8" L$3.47/ft. Total Material Cost$675 Shipping$50 LaborHourly RateTotal Labor Design$3060 hrs Machinist$2516 hrs Total Labor Cost$2200 Grand Total$2925

20. Questions?