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C-arm Fluoroscopy: Developing a Method for Orthotic Analysis

C-arm Fluoroscopy: Developing a Method for Orthotic Analysis. Lisa Friedland Department of Medical Biophysics University of Western Ontario London , Ontario. Acknowledgements. Thomas Jenkyn , Ph.D., P.Eng Megan Balsdon , MSc. Candidate Kristen Bushey , MSc. Candidate. Question.

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C-arm Fluoroscopy: Developing a Method for Orthotic Analysis

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  1. C-arm Fluoroscopy: Developing a Method for Orthotic Analysis 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 individuals—flexible • 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. Barefoot • Neutral shoe • Soft foam box shoe • Soft plaster cast shoe • Rigid foam box shoe • Rigid plaster cast shoe Experimental Design

  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 B A A B

  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 • Asexpected • Barefoot – 121.66° • Neutral shoe – 115.96° • Soft plaster – 113.65° • Rigid plaster – 112.22° • More support—C1MA angle decreases • Inconclusive • Data collection ongoing • Problematic images

  13. 1st 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 & B—calibrate 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: http://www.industry-medical.com/mymedical/ajmedical/prodetail2284/AJ4501_High_Frequency_Mobile_C-Arm_Xray_Imaging_System.html 2. normal/high/flat: http://www.footlogics.ie/pronation-flatfeet-fallen-arches.html & http://www.youcanbefit.com/shoes.html 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, 1-13. 4. Allen, A, M. (2009). Development and validation of a markerless RSA system. Thesis. Biomedical Engineering, University of Western Ontario: London.

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