1. seminar/seminar052920 02/ming.ppt 1 Tacking the challenges to professional education arising from the pace of technological development and the need for lifelong learningSub-project Computer-Aided Learning for Prosthetic Designs Ming ZHANG, Arthur FT Mak, Hok Sum MAN Jockey Club Rehabilitation Engineering Centre The Hong Kong Polytechnic University Yubo FAN, Fang PU, Wentao JIANG Sichuan University, China PolyU IGARD Project The Hong Kong POLYTECHNIC UNIVERSITY Rehabilitation Engineering Centre

2. seminar/seminar052920 02/ming.ppt 2 Objective To develop a computer-aided teaching/learning package which can help students to better understand the design of a lower-limb prosthesis BSc in Prosthetics & Orthotics in Health Technology

3. seminar/seminar052920 02/ming.ppt 3 Background Prosthetic socket are important.Functional & Comfort requirements Custom-made for individuals Lower-limb prosthesis modular components Socket human-device interface

4. seminar/seminar052920 02/ming.ppt 4 Posterior Tissue PosteriorLateralAnterior Patella Tendon Interosseous Groove Medial Shaft Tibial tuberosity Fibular head Fibular end Mid of Fibula Harmstring Tendon Background Relief pressures on Pressure Intolerant Area of residual limb to prevent pain or injure. Apply forces on Pressure Tolerant Areas to hold prosthesis firmly on the residual limb. The shape of a prosthetic socket should be different from residual limb shape

5. seminar/seminar052920 02/ming.ppt 5 Major Concerns for Socket Design Prosthetic socket modification depends on individual experience. How to assess/validate the design? What is the rationale behind the design? Shape modification Based on the Residual limb shape How deep of modification should be applied?

6. seminar/seminar052920 02/ming.ppt 6 Present Problem of Socket validation Validation of design socket shape is expansive and time consuming. Mill the shape with CAM system and model the check socket with thermoplastic. (Material Cost: $800 for each trial.) Check socket should be made to validate the designed socket shape. Cost: $800

7. seminar/seminar052920 02/ming.ppt 7 Research showed that the load distribution between socket and residual limb is critical for comfort and functions Shall can develop something to predict the interaction between socket and limb during walking for a designed socket before fabricated? It can Save time Save materials Reduce errors Better understanding

8. seminar/seminar052920 02/ming.ppt 8 Methods Develop Prosthetic Socket Assessment System (PSAS) Based on Computational Modeling (Finite Element Methods) To predict the load distribution on socket

9. seminar/seminar052920 02/ming.ppt 9 1.Residual limb shape captured from traditional CAD System Residual limb Negative cast with plaster bandage Scanning Residual limb shape with Biosculptor Digitized Residual limb shape Finite Element (FE) Analysis

10. seminar/seminar052920 02/ming.ppt 10 Finite Element (FE) Analysis 2. Designed socket shape using CAD System Digitized Residual limb shape Designed Socket shape file Modified residual Limb model in CAD System

11. seminar/seminar052920 02/ming.ppt 11 Finite Element (FE) Analysis 3.Soft tissue thickness and stiffness to predict the bone shape and position TUPS was used to determined the soft tissue thickness and stiffness Several landmarks on residual limb were selected to determined those mechanical properties The mechanical properties were saved in PSAS to predict the bone shape

12. seminar/seminar052920 02/ming.ppt 12 Finite Element (FE) Analysis of PSAS Soft tissue thickness and stiffness on residual limb Designed Socket shape Residual limb shape captured from traditional CAD System Select loading case Hard tissue determination FE model

13. seminar/seminar052920 02/ming.ppt 13 Finite Element (FE) Analysis After predicting force distributions on residual limb in different loading cases, PSAS shows weather or not the designed socket is suitable for the patient in different ways.

14. seminar/seminar052920 02/ming.ppt 14 Report Different Regions of the designed socket may be selected manually to show the pressure variations during stance phase. Full report of predicted pressure variation is given automatically.

15. seminar/seminar052920 02/ming.ppt 15

16. seminar/seminar052920 02/ming.ppt 16 Report FE models can be browsed into single window to compare the pressure variation during walking.

17. seminar/seminar052920 02/ming.ppt 17 Summary This project developed a CAT platform which allows students to evaluate their socket design before socket is manufactured to understand the rationale behind the socket modification.