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Lisa Friedland Department of Medical Biophysics University of Western Ontario London, Ontario.

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Presentation on theme: "Lisa Friedland Department of Medical Biophysics University of Western Ontario London, Ontario."— Presentation transcript:

1 Lisa Friedland Department of Medical Biophysics University of Western Ontario London, Ontario

2 Acknowledgements Thomas Jenkyn, Ph.D., P.Eng Megan Balsdon, MSc. Candidate Kristen Bushey, MSc. Candidate

3 Question How does a podiatrist/orthotist know that a custom made orthotic is functioning effectively during dynamic gait? Create a method to analyze the orthotic in real time motion.

4 What is C-arm Fluoroscopy? Live feed X-ray technique aka X-ray Image Intensifier Uses an image intensifier to amplify low intensity X-rays CCD camera coupled to the image intensifier displays feed on monitor Features Recording Zoom & contrast adjustments Last image hold Medical Uses Cardiac catheterization Barium investigations Guide placement of medical devices 1. c-arm fluoroscope

5 Orthotic Type Rigid Preferred for flat footed individuals Support, stability, & control Proper fitting extremely important Soft Preferred for high-arched individualsflexible Cushioning, balance, & shock absorption Shorter lifespan Rigid Soft

6 Molding Technique: Plaster Casting vs. Foam Box Plaster Casting Leading technique Foot placed in subtalar joint neutral position Costly, messy Foam Box Quick, clean Allows for natural soft tissue deformation Accommodative mold

7 Experimental Design 21 patients7 flat foot7 normal7 high arch Barefoot Neutral shoe Soft foam box shoe Soft plaster cast shoe Rigid foam box shoe Rigid plaster cast shoe

8 Experimental Design Patients walk on a platform 2 C-arm fluoroscopes Camera A – lateral view Camera B – anterior/oblique view Pull string on each fluoroscope to mark time for syncing

9 2D Arch Analysis Using camera A (lateral) freeze frame as entire foot touches down Measure calcaneal first metatarsal angle (C1MA) in Matlab 3. C1MA protocol

10 Barefoot Dynamic

11 Rigid Foam Box Dynamic

12 Progress so far As expected Barefoot – ° Neutral shoe – ° Soft plaster – ° Rigid plaster – ° More supportC1MA angle decreases Inconclusive Data collection ongoing Problematic images

13 1 st Metatarsal Out of Image

14 Problem with 2D Analysis Out of plane rotation Foot must strike exactly 90° with camera A Put markers on floor Still not realistic

15 Future 3D Analysis Radiostereometric Analysis (RSA) Calibration box Image from cameras A & Bcalibrate using Matlab Digitize the image frames in Adobe Photoshop Import 3D CT image into Rhinoceros modelling software Bone match CT image to Fluoroscope image

16 4. RSA system

17 Images 1. c-arm fluoroscope: medical.com/mymedical/ajmedical/prodetail2284/AJ4501_High_Frequency_Mobile_C- Arm_Xray_Imaging_System.html 2. normal/high/flat: & 3. C1MA protocol: Murley, G., Menz, H., & Landorff, K. (2009). A protocol for classifying normal-and flat- arched foot posture for research studies using clinical and radiographic measurements. Journal of Foot and Ankel Research, 2, 22, Allen, A, M. (2009). Development and validation of a markerless RSA system. Thesis. Biomedical Engineering, University of Western Ontario: London.


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