1. Device for Collecting Stress Images of Subtalar Joint
Patrick Melton
Daniel Escobar
12/2/10

2. Introduction
It is difficult to determine if the subtalar joint is unstable through current methods of examination due to the cost and difficulty of use of the equipment necessary to make reliable measurements.
Producing radiographs to allow for accurate measurements of the subtalar joint for stability analysis has been refined for more practical uses.

3. Purpose
Create a device that will align the subtalar joint to allow for the best possible radiograph and measurements to determine the stability of the joint.

4. Hindfoot Anatomy

5. Literature Review – Radiography
Various radiograph views to assess the subtalar joint.
Cobey view (20°)
Long axial view (45°)
Similar Devices
Telos Device
“Hinge Device”
Dynastat

6. 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),

7. Long Axial Alignment View
Most reliable and accurate measurements, highest correlation coefficients.
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),

8. Current Progress
Weekly meetings with project advisors discussing literature review, conceptual designs, and future objectives.
Literature Review
Subtalar joint anatomy
Methods of radiographing the subtalar joint for best possible measurements.
Telos device – same concept but difficult to use.

9. Current Progress (cont’d.)
Considering conceptual designs for stress device
Meeting with Portsmouth Naval Surgeon to discuss potential design ideas
Modeling preliminary designs in Solid Works

10. Design Considerations
Design allows for inversion of the calcaneus for hindfoot assessment in weight bearing position.
Price, Mark. (Designer). (2006). Measuring hindfoot with dynastat. [Web]. Retrieved from

11. Design Considerations (Ctd)
Applies non-weight bearing inversion stress.
Allows for analysis of subtalar tilt angle.
Brantigan, JW, Pedegana, LR, Lippert, FG Instability of the subtalar joint. Diagnosis by stress tomography in three cases J Bone Joint Surg Am :

12. Initial Design

13. Initial Design (Ctd)

14. Future Objectives
Model the designs in Solid Works and analyze Finite Element model for stresses and factors of safety.
Discuss designs with advisors and make any necessary modifications.
Determine materials needed for constructing device and the cost of the design.

15. Schedule