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Changes in Internal Prosthetic Moment with Walking Speed: A Case Study.

Changes in Internal Prosthetic Moment with Walking Speed: A Case Study. Jason Wening MS, CPO Mark Kaiser, CO, prosthetic resident. As speed increases…. Gait asymmetry increases. (Isakov et al., 1996) Peak GRF increases. (Nolan et al.,2003)

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Changes in Internal Prosthetic Moment with Walking Speed: A Case Study.

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  1. Changes in Internal Prosthetic Moment with Walking Speed: A Case Study. Jason Wening MS, CPO Mark Kaiser, CO, prosthetic resident

  2. As speed increases… • Gait asymmetry increases. (Isakov et al., 1996) • Peak GRF increases. (Nolan et al.,2003) • Ankle work in both limbs increases. (Silverman et al., 2008) • Muscle EMG increases, especially at initial contact. (Fey et al., 2010)

  3. Quantifying Dynamic Alignment • Difficult to do with a gait lab. (Van Velzen et al., 2006) • Good walkers manage moments well? • Resolution may not be sufficient? • Roll over shape may be useful. (Hansen ) • Alignment is a 6 DoF problem.

  4. A new clinical tool: Compass and Smart Pyramid • Pyramid with integrated strain gauges. • Software computes moments in the sagittal and coronal planes.

  5. - + Would a moment by any other name torque the same?

  6. Purpose of this study • Determine how the moment profile from the Compass System changes with walking speed for a single subject.

  7. Subject • 36 y.o. M, R Trans-tibial amputee • K4 level ambulator • Suction TSB socket with gel liner, dynamic response foot

  8. Methodology • Nine walks were collected at a range of walking speeds in a 20 meter hallway. • Data collected in middle 10 meters. • Velocity computed from 10m walk time. • Moment collected using OI Compass and Smart Pyramid at 100 Hz.

  9. - + A Matter of Semantics? GRF Posterior to Smart Pyramid: Recorded as a negative moment about the smart pyramid in the sagittal Plane Posterior Moment

  10. - + A Matter of Semantics? GRF through Smart Pyramid: Recorded as zero moment about the smart pyramid in the sagittal Plane

  11. - + A Matter of Semantics? GRF Anterior to Smart Pyramid: Recorded as a positive moment about the smart pyramid in the sagittal Plane Anterior Moment

  12. Anterior Posterior * = compass approved Velocity (m/s)

  13. Lateral Medial Velocity (m/s)

  14. Conclusions • Walking speed changes the moment profile as recorded by the Compass System. • With increased speed peak heel and keel moments increase. • With increased speed, relative timing of transition across 0 axis did not change. • Aprox. 33% of stance phase.

  15. Discussion • What is the true quantitative definition of optimal alignment? • Is it speed dependent?….. • Is it device dependent?….. • Is it patient dependent?….. • An effort needs to be made to characterize the Compass system and make that data available to users.

  16. Calling all Prosthetic Residents • What is the relationship between: • Foot type, • Socket design, • Socket fit, • Limb length, • Age, gender, 2nd condition, time since amputation, • Cause of amputation, • Use of assistive device… • and internal moment.

  17. Acknowledgements • Orthocare Innovations

  18. Zero transition occurred at: 32.89% +/- 1% of stance phase

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