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Effects of prosthetic ankle power and foot stiffness category on biomechanical asymmetry and knee moment during walking at different speeds
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  • Published: 04 February 2026

Effects of prosthetic ankle power and foot stiffness category on biomechanical asymmetry and knee moment during walking at different speeds

  • Joshua R. Tacca  ORCID: orcid.org/0000-0003-2273-821X1,2,
  • Zane A. Colvin  ORCID: orcid.org/0000-0003-0293-29122 &
  • Alena M. Grabowski  ORCID: orcid.org/0000-0002-4432-618X2,3 

Scientific Reports , Article number:  (2026) Cite this article

We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Subjects

  • Biomedical engineering
  • Biophysics
  • Rehabilitation
  • Translational research

Abstract

People with unilateral transtibial amputation (uTTA) using a passive-elastic prosthesis typically walk with contact time (tc) and first and second peak vertical ground reaction force (F1 and F2) asymmetry and greater first peak external knee adduction moment in their unaffected versus affected leg. A previous study found that use of stance-phase powered prosthesis (BiOM) at a recommended power setting compared to a passive-elastic prosthesis can reduce tc asymmetry at self-selected speed and unaffected leg first peak external knee adduction moment at 1.50–1.75 m/s. However, the BiOM includes a passive-elastic prosthesis that can have different stiffness categories and can be tuned to different power settings, which may affect tc and F1 and F2 asymmetry and unaffected leg first peak external knee adduction moment. Thirteen people with uTTA used 16 different passive-elastic prosthetic foot stiffness categories and BiOM power settings to walk at 0.75–1.75 m/s. We found that use of the stiffest compared to least stiff category reduced F2 asymmetry. Use of the BiOM reduced tc asymmetry compared to a passive-elastic prosthesis and the effects of power setting on F1 and F2 asymmetry depended on walking speed. To minimize biomechanical asymmetry during walking at 1.25 m/s, people with uTTA should use the BiOM with power settings up to 20% greater than those that match biological ankle joint biomechanics. Such prosthetic settings could potentially reduce unaffected leg joint pain and/or osteoarthritis risk.

Data availability

Data is available in the text and supplementary materials. Additional requests can be directed to the corresponding author.

Abbreviations

+ 1 Cat:

One category stiffer than recommended

+ 10%:

10% greater than recommended power setting

+ 20%:

20% greater than recommended power setting

-1 Cat:

One category less stiff than recommended

-2 Cat:

Two categories less stiff than recommended

AL:

Affected leg

Cat:

Prosthetic stiffness category

EKAM:

External knee adduction moment

F1 :

First peak vertical ground reaction force

F2 :

Second peak vertical ground reaction force

Fig.:

Figure

LP:

Low-profile

Rec:

Recommended

SEM:

Standard error of the mean

SI:

Symmetry index

tc :

Contact time

UL:

Unaffected leg

uTTA:

Unilateral transtibial amputation

References

  1. Zmitrewicz, R. J., Neptune, R. R. & Sasaki, K. Mechanical energetic contributions from individual muscles and elastic prosthetic feet during symmetric unilateral transtibial amputee walking: A theoretical study. J. Biomech. 40(8), 1824–1831 (2007).

    Google Scholar 

  2. Morgenroth, D. C. et al. The effect of prosthetic foot push-off on mechanical loading associated with knee osteoarthritis in lower extremity amputees. Gait Posture. 34(4), 502–507 (2011).

    Google Scholar 

  3. Sanderson, D. J. & Martin, P. E. Joint kinetics in unilateral below-knee amputee patients during running. Arch. Phys. Med. Rehabil. 77(12), 1279–1285 (1996).

    Google Scholar 

  4. Bateni, H. & Olney, S. J. Kinematic and kinetic variations of below-knee amputee gait. JPO J. Prosthetics Orthot. 14(1), 2–10 (2002).

    Google Scholar 

  5. Royer, T. D. & Wasilewski, C. A. Hip and knee frontal plane moments in persons with unilateral, trans-tibial amputation. Gait Posture. 23(3), 303–306 (2006).

    Google Scholar 

  6. Adamczyk, P. G. & Kuo, A. D. Mechanisms of gait asymmetry due to push-off deficiency in unilateral amputees. IEEE Trans. Neural Syst. Rehabil Eng. 23(5), 776–785 (2015).

    Google Scholar 

  7. D’Andrea, S., Wilhelm, N., Silverman, A. K. & Grabowski, A. M. Does use of a powered ankle-foot prosthesis restore whole-body angular momentum during walking at different speeds? Clin. Orthop. Relat. Res. 472(10), 3044–3054 (2014).

    Google Scholar 

  8. Morgenroth, D. C., Gellhorn, A. C. & Suri, P. Osteoarthritis in the disabled population: A mechanical perspective. PM&R 4(5), S20–S27 (2012).

    Google Scholar 

  9. Struyf, P. A., van Heugten, C. M., Hitters, M. W. & Smeets, R. J. The prevalence of osteoarthritis of the intact hip and knee among traumatic leg amputees. Arch. Phys. Med. Rehabil. 90(3), 440–446 (2009).

    Google Scholar 

  10. Norvell, D. C. et al. The prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees. Arch. Phys. Med. Rehabil. 86(3), 487–493 (2005).

    Google Scholar 

  11. Kulkarni, J., Gaine, W. J., Buckley, J. G., Rankine, J. J. & Adams, J. Chronic low back pain in traumatic lower limb amputees. Clin. Rehabil. 19(1), 81–86 (2005).

    Google Scholar 

  12. D’Souza, N. et al. Are biomechanics during gait associated with the structural disease onset and progression of lower limb osteoarthritis? A systematic review and meta-analysis. Osteoarthr. Cartil. 30(3), 381–394 (2022).

    Google Scholar 

  13. Chang, A. H. et al. External knee adduction and flexion moments during gait and medial tibiofemoral disease progression in knee osteoarthritis. Osteoarthr. Cartil. 23(7), 1099–1106 (2015).

    Google Scholar 

  14. Ruxin, T. R. et al. Comparing forefoot and heel stiffnesses across commercial prosthetic feet manufactured for individuals with varying body weights and foot sizes. Prosthet. Orthot. Int. https://doi.org/10.1097/PXR.0000000000000131 (2022).

    Google Scholar 

  15. Össur, L. P. Vari-Flex Instructions for Use. https://media.ossur.com/image/upload/pi-documents-global/PN20178_LP_VariFlex.pdf.

  16. Zelik, K. E. et al. Systematic variation of prosthetic foot spring affects center-of-mass mechanics and metabolic cost during walking. IEEE Trans. Neural Syst. Rehabil. Eng. 19(4), 411–419 (2011).

    Google Scholar 

  17. Klodd, E., Hansen, A., Fatone, S. & Edwards, M. Effects of prosthetic foot forefoot flexibility on gait of unilateral transtibial prosthesis users. J. Rehabil Res. Dev. 47(9), 899–909 (2010).

    Google Scholar 

  18. Fey, N. P., Klute, G. K. & Neptune, R. R. The influence of energy storage and return foot stiffness on walking mechanics and muscle activity in below-knee amputees. Clin. Biomech. Elsevier Ltd. 26(10), 1025–1032 (2011).

    Google Scholar 

  19. Major, M. J., Twiste, M., Kenney, L. P. J. & Howard, D. The effects of prosthetic ankle stiffness on ankle and knee kinematics, prosthetic limb loading, and net metabolic cost of trans-tibial amputee gait. Clin. Biomech. Elsevier Ltd. 29(1), 98–104 (2014).

    Google Scholar 

  20. Adamczyk, P. G., Roland, M. & Hahn, M. E. Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses. Hum. Mov. Sci. 54, 154–171 (2017).

    Google Scholar 

  21. Halsne, E. G., Czerniecki, J. M., Shofer, J. B. & Morgenroth, D. C. The effect of prosthetic foot stiffness on foot-ankle biomechanics and relative foot stiffness perception in people with transtibial amputation. Clin. Biomech. Elsevier Ltd. 80, 105141 (2020).

    Google Scholar 

  22. Rogers-Bradley, E., Yeon, S. H., Landis, C., Lee, D. R. C. & Herr, H. M. Variable-stiffness prosthesis improves biomechanics of walking across speeds compared to a passive device. Sci. Rep. 14(1), 16521 (2024).

    Google Scholar 

  23. Slater, C., Halsne, E. G., Czerniecki, J. M. & Morgenroth, D. C. The effect of prosthetic foot stiffness category on intact limb knee loading associated with osteoarthritis in people with transtibial amputation. J. Biomech. 176, 112368 (2024).

    Google Scholar 

  24. Tacca, J. R., Colvin, Z. A. & Grabowski, A. M. Greater than recommended stiffness and power setting of a stance-phase powered leg prosthesis can improve step-to-step transition work and effective foot length ratio during walking in people with transtibial amputation. Front. Bioeng. Biotechnol. https://doi.org/10.3389/fbioe.2024.1336520/full (2024).

    Google Scholar 

  25. Adamczyk, P. G., Collins, S. H. & Kuo, A. D. The advantages of a rolling foot in human walking. J. Exp. Biol. 209(20), 3953–3963 (2006).

    Google Scholar 

  26. Au, S. K., Weber, J. & Herr, H. Powered ankle–foot prosthesis improves walking metabolic economy. IEEE Trans. Robot. 25(1), 51–66 (2009).

    Google Scholar 

  27. Herr, H. M. & Grabowski, A. M. Bionic ankle–foot prosthesis normalizes walking gait for persons with leg amputation. Proc. Royal Soc. B: Biol. Sci. 279(1728), 457–464 (2012).

    Google Scholar 

  28. Quesada, R. E., Caputo, J. M. & Collins, S. H. Increasing ankle push-off work with a powered prosthesis does not necessarily reduce metabolic rate for transtibial amputees. J. Biomech. 49(14), 3452–3459 (2016).

    Google Scholar 

  29. Caputo, J. M. & Collins, S. H. Prosthetic ankle push-off work reduces metabolic rate but not collision work in non-amputee walking. Sci. Rep. 4(1), 7213 (2014).

    Google Scholar 

  30. Eilenberg, M. F., Geyer, H. & Herr, H. Control of a powered ankle–foot prosthesis based on a neuromuscular model. IEEE Trans. Neural Syst. Rehabil. Eng. 18(2), 164–173 (2010).

    Google Scholar 

  31. Ferris, A. E., Aldridge, J. M., Rábago, C. A. & Wilken, J. M. Evaluation of a powered ankle–foot prosthetic system during walking. Arch. Phys. Med. Rehabil. 93(11), 1911–1918 (2012).

    Google Scholar 

  32. Grabowski, A. M. & D’Andrea, S. Effects of a powered ankle-foot prosthesis on kinetic loading of the unaffected leg during level-ground walking. J. Neuroeng. Rehabil. 10(1), 1–12 (2013).

    Google Scholar 

  33. Russell Esposito, E. & Wilken, J. M. Biomechanical risk factors for knee osteoarthritis when using passive and powered ankle–foot prostheses. Clin. Biomech. Elsevier Ltd. 29(10), 1186–1192 (2014).

    Google Scholar 

  34. Ingraham, K., Choi, H., Gardinier, E., Remy, C. & Gates, D. Choosing appropriate prosthetic ankle work to reduce the metabolic cost of individuals with transtibial amputation. Sci. Rep. 8 (2018).

  35. iWalk, I. Tuning Instructions for BiOM T2: Technical Manual Addendum. (2013).

  36. Esposito, E. R., Whitehead, J. M. A. & Wilken, J. M. Step-to-step transition work during level and inclined walking using passive and powered ankle-foot prostheses. Prosthet. Orthot. Int. 40(3), 311–319 (2016).

    Google Scholar 

  37. Gardinier, E. S., Kelly, B. M., Wensman, J. & Gates, D. H. A controlled clinical trial of a clinically-tuned powered ankle prosthesis in people with transtibial amputation. Clin. Rehabil. 32(3), 319–329 (2018).

    Google Scholar 

  38. Kim, J., Wensman, J., Colabianchi, N. & Gates, D. H. The influence of powered prostheses on user perspectives, metabolics, and activity: a randomized crossover trial. J. Neuroeng. Rehabil. 18(1), 49 (2021).

    Google Scholar 

  39. Balk, E. M. et al. Table 1, lower limb extremity prosthesis medicare functional classification levels (K levels). (Accessed 3 Apr 2023) https://www.ncbi.nlm.nih.gov/books/NBK531517/table/ch2.tab1/ (Agency for Healthcare Research and Quality (US), 2018).

  40. Montgomery, J. R. & Grabowski, A. M. Use of a powered ankle-foot prosthesis reduces the metabolic cost of uphill walking and improves leg work symmetry in people with transtibial amputations. J. R Soc. Interface. 15(145), 20180442 (2018).

    Google Scholar 

  41. Jeffers, J. R., Auyang, A. G. & Grabowski, A. M. The correlation between metabolic and individual leg mechanical power during walking at different slopes and velocities. J. Biomech. 48(11), 2919–2924 (2015).

    Google Scholar 

  42. Robinson, R., Herzog, W. & Nigg, B. Use of force platform variables to quantify the effects of chiropractic manipulation on gait symmetry. J. Manip Physiol. Ther. 10(4), 172–176 (1987).

    Google Scholar 

  43. Dempster, W. T. Space Requirements of the Seated operator, geometrical, kinematic, and Mechanical Aspects of the Body with Special Reference To the Limbs (Michigan State Univ East Lansing, 1955).

  44. Ferris, A. E., Smith, J. D., Heise, G. D., Hinrichs, R. N. & Martin, P. E. A general model for estimating lower extremity inertial properties of individuals with transtibial amputation. J. Biomech. 54, 44–48 (2017).

    Google Scholar 

  45. Bates, D., Mächler, M., Bolker, B. & Walker, S. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67(1), 1–48 (2015).

    Google Scholar 

  46. Kuznetsova, A., Brockhoff, P. B. & Christensen, R. H. B. LmerTest package: tests in linear mixed effects models. J. Stat. Softw. 82(1), 1–26 (2017).

    Google Scholar 

  47. Cohen, J. Statistical Power Analysis for the Behavioral Sciences 579 (Routledge, 2013).

  48. Faul, F., Erdfelder, E., Lang, A. G. & Buchner, A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav. Res. Methods. 39(2), 175–191 (2007).

    Google Scholar 

  49. Tacca, J. R., Colvin, Z. A. & Grabowski, A. M. Low-profile prosthetic foot stiffness category and size, and shoes affect axial and torsional stiffness and hysteresis. Front. Rehabil Sci. https://doi.org/10.3389/fresc.2024.1290092 (2024).

    Google Scholar 

  50. Manal, K., Gardinier, E., Buchanan, T. S. & Snyder-Mackler, L. A more informed evaluation of medial compartment loading: the combined use of the knee adduction and flexor moments. Osteoarthr. Cartil. 23(7), 1107–1111 (2015).

    Google Scholar 

  51. Hendershot, B. D. & Wolf, E. J. Three-dimensional joint reaction forces and moments at the low back during over-ground walking in persons with unilateral lower-extremity amputation. Clin. Biomech. Elsevier Ltd. 29(3), 235–242 (2014).

    Google Scholar 

  52. Riley, P. O., Paolini, G., Della Croce, U., Paylo, K. W. & Kerrigan, D. C. A kinematic and kinetic comparison of overground and treadmill walking in healthy subjects. Gait Posture. 26(1), 17–24 (2007).

    Google Scholar 

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Funding

This study was funded by a Department of Veterans Affairs Rehabilitation Research and Development Service merit review award (I01 RX002941).

Author information

Authors and Affiliations

  1. Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA

    Joshua R. Tacca

  2. Department of Integrative Physiology, University of Colorado, Boulder, CO, USA

    Joshua R. Tacca, Zane A. Colvin & Alena M. Grabowski

  3. Department of Veterans Affairs, Eastern Colorado Healthcare System, Denver, CO, USA

    Alena M. Grabowski

Authors
  1. Joshua R. Tacca
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  2. Zane A. Colvin
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Contributions

All authors reviewed and edited the manuscript. J.T. collected the data, developed the methodology, did the formal data analysis, prepared figures, and wrote the main manuscript text. Z.C. collected the data and developed the methodology. A.G. acquired the funding, conceptualized the experiment, provided resources and supervision, and developed the methodology.

Corresponding author

Correspondence to Joshua R. Tacca.

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The participants gave informed consent for publication of the data included in this article.

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The participants in this study gave written informed consent to participate in the protocol. The study protocol was approved by the United States Department of Veteran Affairs’ Human Subjects Institutional Review Board (COMIRB #19-1052) and all studies were conducted in accordance with local legislation and institutional requirements.

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The authors declare no competing interests.

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Tacca, J.R., Colvin, Z.A. & Grabowski, A.M. Effects of prosthetic ankle power and foot stiffness category on biomechanical asymmetry and knee moment during walking at different speeds. Sci Rep (2026). https://doi.org/10.1038/s41598-026-37225-3

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  • Received: 09 January 2025

  • Accepted: 20 January 2026

  • Published: 04 February 2026

  • DOI: https://doi.org/10.1038/s41598-026-37225-3

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Keywords

  • Prostheses
  • Amputee
  • Bionic
  • Kinetics
  • Injury
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