1. 1 Evaluation of Alignment Methods for Transtibial Prostheses Missy Malkush Masters Research Presentation Georgia Tech, MSPO 2008 April 16, 2008

2. 2 Intro: Developing Countries 3-4 million people in need of a prosthesis (Murdoch 1990) 3-4 million people in need of a prosthesis (Murdoch 1990) <5% people have access to medical care (WHO, 2003) <5% people have access to medical care (WHO, 2003) –80% in remote, rural areas (Sethi, 1989) –Unaffordable –Few trained specialists

3. 3 Intro: Monolimb Appropriate Technology Fewer components Fewer components Affordable Affordable Durable Durable Delivered on initial fit (Valenti 2001) Delivered on initial fit (Valenti 2001) >1,000 fittings >1,000 fittings –Burma, Thailand, China, Vietnam, El Salvador Monolimb initial fit, Burma 2007

4. 4 Delivery of Definitive Prosthesis * Eliminate modular components and trained prosthetist Static Alignment Dynamic Alignment Delivery of Definitive Prosthesis Intro: Prosthetic Alignment Modular Design Bench Alignment Monolimb Monolimb fabrication, Thailand 2007 www.ap.gatech.edu/mspo

5. 5 Intro: Appropriate Alignment “…good alignment can be achieved on the basis of [patient] measurements, if an easy procedure and fabrication fixture can be developed to assist with alignment…” CIR 2007 “…good alignment can be achieved on the basis of [patient] measurements, if an easy procedure and fabrication fixture can be developed to assist with alignment…” CIR 2007 Two Alignment Methods: VAA, ABA

6. 6 Research Goal Question: Which alignment method (VAA, ABA, TRAD) requires the least magnitude of alignment changes to result in optimal gait? Hypothesis: An alignment method based on patient measurements (VAA, ABA) will require a lower magnitude of change to arrive at appropriate prosthetic alignment.

7. 7 Methods: Subjects 8 transtibial amputees 8 transtibial amputees –18-65yo, <220lbs, healthy 8 students of prosthetics 8 students of prosthetics –Georgia Tech, MSPO –NUPOC 2 prosthetists per amputee/student pair 2 prosthetists per amputee/student pair

8. 8 Protocol: Alignment Capture 1. Student captures VAA, ABA alignments on amputee

9. 9 Vertical Alignment Axis (VAA) Socket center at PTB level projects onto alignment reference center Socket center at PTB level projects onto alignment reference center Socket angles determined by natural attitude of limb during weight bearing Socket angles determined by natural attitude of limb during weight bearing Wu et al, 1981

10. 10 Vertical Alignment Axis (VAA) Coronal and sagittal planes intersection Coronal and sagittal planes intersection Vertical Alignment Axis

11. 11 Anatomical Based Alignment (ABA) Hip, knee, and ankle joint centers lie along a common axis in frontal and sagittal planes. Hip, knee, and ankle joint centers lie along a common axis in frontal and sagittal planes.

12. 12 3. Prosthetists dynamically align 3 prostheses Quantify dynamic alignments Quantify dynamic alignments Protocol: Assemble and Dynamically Align 2. Students assemble 3 prostheses –VAA, ABA, TRAD Quantify bench alignments Quantify bench alignments

13. 13 Data Alignment Parameters Quantitative 1. Height 2. Toe-out 3. Foot posterior 4. Socket flexion 5. Foot inset 6. Socket adduction

14. 14 Results No statistical No statistical significance (p<0.05) by repeated measures analysis

15. 15 Discussion: Zahedi et al, 1986 Alignment of Lower Limb Prostheses Alignment of Lower Limb Prostheses –A wide range of alignments are considered acceptable by the amputee and prosthetist –Average acceptable ranges 45mm socket shifts 45mm socket shifts 10º socket tilts 10º socket tilts –Values depend on patient activity level and level of amputation

16. 16 Discussion Where these magnitudes of change of any significance to the amputee? Where these magnitudes of change of any significance to the amputee?

17. 17 Discussion: Amputee Subjective Feedback

18. 18 Conclusion Hypothesis: An alignment method based on patient measurements (VAA, ABA) will require a lower magnitude of change to arrive at appropriate prosthetic alignment. NOT SUPPORTED NOT SUPPORTED

19. 19 Limitations Soft heel of SACH foot Soft heel of SACH foot Student inexperience Student inexperience ABA ABA –Difficulty palpating anatomy –Does surface anatomy correspond to joint centers? VAA and ABA VAA and ABA –Base of support assumed “fist-width apart”

20. 20 Future Directions Control student, vary amputees Control student, vary amputees Test accuracy of alignment methods -or- Control amputees, vary student Control amputees, vary student Test if little training is necessary Test if little training is necessary-or- Control student, vary amputee BMI Control student, vary amputee BMI Test effects of body composition Test effects of body composition

21. 21References Murdoch G. Editorial. Prosthet Orthot Int 1990;9(1):1-2. Sethi PK. The Knud Jensen Lecture- Technological choices in prosthetics and orthotics for developing countries. Prosthet Orthot Int 1989;13:117-124. Valenti T. Experience with endoflex: a monolithic thermoplastic prosthesis for below-knee amputees. J Prosth Orth 2001;3(1):43-50. Walsh NE, Walsh WS. Rehabilitation of landmine victims – the ultimate challenge. Bulletin of the World Health Organization 2003;81(9):1-12. Wu Y, Crncick MD, Krick HJ, Putnam TD, Stratigos JS. Scotchcast PVC interim prosthesis for below-knee amputees. Bulletin of Prosthetics Research 1981;fall:40-45. Zahedi MS, Spence WD, Solomonidis SE, Paul JP. Alignment of lower-limb prostheses. J Rehab Research 1986;23(2):2-19. *Photographs courtesy of Jody Riggs, BCIT ’08. Burma- Thailand 2007.

22. 22 Monolimb Recipient, Burma 2007 Andrea Ikeda Rob Kistenberg Rob Macdonald Dr. Gregor Dr. Teresa Snow Scott C My classmates My subjects Special Thanks

23. 23 X Methods Height, ABA Height, VAA Alignment Board Toe out, VAA

24. 24 Alignment Board Align 3 things: Align 3 things: –Etched line on plexiglass –Marker line on board –Marker alignment line on socket

25. 25 Step Asymmetry

26. 26 Averaged Results Height (mm)Toe out (º)Foot inset (mm) Socket flexion (º) Foot posterior (mm) Socket adduction (º)

27. 27 Monolimb Recipients