Annals of Biomedical Engineering

, Volume 43, Issue 2, pp 427–441 | Cite as

State of the Art Review of Knee–Ankle–Foot Orthoses

  • Feng Tian
  • Mohamed Samir HefzyEmail author
  • Mohammad Elahinia


Knee–ankle–foot orthoses (KAFOs) are used to assist in ambulation. The purpose of this paper is to review existing KAFO designs which can be grouped into passive KAFOs, stance control (SC) KAFOs, and dynamic KAFOs. The conventional passive KAFOs do not provide any active control for knee motions. SCKAFOs lock the knee joint during the stance phase and allow free rotations during the swing phase. Some SCKAFOs switch between the stance and swing phases using body posture, while others use some kind of a control system to perform this switch. Finally, dynamic KAFOs control the knee joint during both stance and swing phases. Four dynamic systems are identified in the literature that use pneumatics, linear springs, hydraulics, and torsional rods made of superelastic alloys to control the knee joint during the gait cycle. However, only the two systems that use linear springs and torsional rods can reproduce the normal knee stiffness pattern which has two distinct characteristics: a soft stiffness during the swing phase and a hard stiffness during the stance phase. This review indicates that there is a need to conduct research regarding new KAFO designs that duplicate normal knee function during the whole gait cycle.


Passive KAFO Stance control KAFO Dynamic KAFO Superelastic alloys Gait cycle 



This work was partially supported by Grant BCS-0931643 from the General & Age Related Disabilities Engineering (GARDE) program from the Biomedical Engineering and Engineering Healthcare cluster of the Chemical, Bioengineering, Environmental, and Transport Systems (CBET) division of the National Science Foundation.


  1. 1.
    Andani, M. T., A. Alipour, and M. Elahinia. Coupled rate-dependent superelastic behavior of shape memory alloy bars induced by combined axial-torsional loading: a semi-analytic modeling. J. Intell. Mater. Syst. Struct. 24:1995–2007, 2013.Google Scholar
  2. 2.
    Arazpour, M., A. Chitsazan, M. A. Bani, G. Rouhi, F. T. Ghomshe, and S. W. Hutchins. The effect of a knee ankle foot orthosis incorporating an active knee mechanism on gait of a person with poliomyelitis. Prosthet Orthot Int. 37:411–414, 2013.CrossRefPubMedGoogle Scholar
  3. 3.
    Hennessey, W. J. Lower limb orthotic devices. In: Physical Medicine and Rehabilitation, edited by R. L. Braddom, L. Chan, M. A. Harrast, K. J. Kowalske, D. J. Matthews, K. T. Ragnarsson, and K. A. Stolp. Philadelphia: Elsevier W. B. Saunders Company, 2011, pp. 333–357.Google Scholar
  4. 4.
    Clark, D. R., J. Perry, and T. R. Lunsford. Case studies—orthotic management of the adult post polio patient. JPO 40:43–50, 1986.Google Scholar
  5. 5.
    Condie, D., and J. Lamb. Knee–ankle–foot orthoses. In: Biomechanical Basis of Orthotic Management, edited by P. Bowker, D. N. Condie, D. L. Bader, D. J. Bratt, and W. A. Wallace. Oxford: Butterworth-Heinemann, 1993, pp. 146–167.Google Scholar
  6. 6.
    Cullell, A., J. C. Moreno, E. Rocon, A. F. Cordero, and J. L. Pons. Biologically based design of an actuator system for a knee–ankle–foot orthosis. Mech Mach Theor. 44:860–872, 2009.CrossRefGoogle Scholar
  7. 7.
    Davids, J. R. Normal gait and assessment of gait disorders. In: Lovell & Winter’s Pediatric Orthopaedics, edited by R. T. Morrissy, and S. L. Weinstein. Philadelphia: Lippincott Williams & Wilkins, 2000, pp. 131–156.Google Scholar
  8. 8.
    Fatone, S. A review of the literature pertaining to KAFOs and HKAFOs for ambulation. JPO 18:137–163, 2006.Google Scholar
  9. 9.
  10. 10.
  11. 11.
  12. 12.
    Hwang, S., S. Kang, K. Chao, and Y. Kim. Biomechanical effect of electromechanical knee-ankle-foot-orthosis on knee joint control in patients with poliomyelitis. Med. Biol. Eng. Comput. 46:541–549, 2008.CrossRefPubMedGoogle Scholar
  13. 13.
    Irby, S. E., K. A. Bernhardt, D. A. Morrow, and K. R. Kaufman. Fatigue test device for stance phase control knee orthoses. JPO 15:143–147, 2003.Google Scholar
  14. 14.
    Irby, S. E., K. R. Kaufman, R. W. Wirta, and D. H. Sutherland. Optimization and application of a wrap-spring clutch to a dynamic KAFO. IEEE Trans Rehabil Eng. 7:130–134, 1999.CrossRefPubMedGoogle Scholar
  15. 15.
    Lagoudas, D. C. Shape Memory Alloys: Modeling and Engineering Applications. New York: Springer Science and Business Media, LLC., pp. 11–15, 2008.Google Scholar
  16. 16.
    McMillan, A. G., K. Kendrick, J. W. Michael, J. Aronson, and G. W. Horton. Preliminary Evidence for Effectiveness of a Stance Control Orthosis. JPO. 16:6–13, 2004.Google Scholar
  17. 17.
    Michael, J. W. Summary from the academy’s seventh state of the science conference on knee-ankle-foot orthoses for ambulation. JPO. 18:132, 2006.Google Scholar
  18. 18.
    Raftopoulos, D. D., L. Poulos, and C. W. Armstrong. Knee-ankle-foot orthotic with a hydraulic twist. SOMA/JANUARY, 1988, pp. 49–53.Google Scholar
  19. 19.
    Redford, J. B., J. V. Basmajian, and P. Trautman. Orthotics: Clinical Practice and Rehabilitation Technology. New York: Churchill Livingstone, 1995.Google Scholar
  20. 20.
    Sawicki, G. S., and D. P. Ferris. A pneumatically powered knee–ankle–foot orthosis with myoelectric activation and inhibition. J Neuroeng Rehabil. 6:23–38, 2009.CrossRefPubMedCentralPubMedGoogle Scholar
  21. 21.
    Shamaei, K., P. C. Napolitano, and A. M. Dollar. Design and functional evaluation of a quasi-passive compliant stance control knee–ankle–foot orthosis. IEEE Trans Rehabil Eng. 22:258–268, 2014.CrossRefGoogle Scholar
  22. 22.
    Tian, F., M. Elahinia, and M. S. Hefzy. A dynamic knee-ankle-foot orthosis with superelastic actuators. Proceedings of the ASME 2013 Conference on Smart Material, Adaptive Structures and Intelligent Systems, Paper #SMASIS2013-3044. September 16–18, 2013, Snowbird, Utah, USA.Google Scholar
  23. 23.
    Tian, F., M. Elahinia, and M. S. Hefzy. Design and evaluation of a knee actuator for a dynamic knee-ankle-foot orthosis. In: Proceedings of the ASME 2014 Conference on Smart Material, Adaptive Structures and Intelligent Systems, Paper #SMASIS2014-7605 (CD publication). September 8–10, 2014, Newport, Rhode Island, USA.Google Scholar
  24. 24.
    Tian, F., M. S. Hefzy, and M. Elahinia. Development of a dynamic knee actuator for a KAFO using superelastic alloys. In: ASME 2014 International Mechanical Engineering Congress and Exposition, Paper #IMECE2014-40431, November 14–20, 2014, Montreal, Canada.Google Scholar
  25. 25.
    Winter, D. A. Biomechanics and Motor Control of Human Movement. Hoboken: John Wiley & Sons Inc, pp. 321–335, 2009.CrossRefGoogle Scholar
  26. 26.
    Yakimovich, T., J. Kofman, and E. D. Lemaire. Design and evaluation of a stance-control knee–ankle–foot orthosis knee joint. IEEE Trans Neural Syst Rehabil Eng. 14:361–369, 2006.CrossRefPubMedGoogle Scholar
  27. 27.
    Yakimovich, T., E. D. Lemaire, and J. Kofman. Engineering design review of stance-control knee–ankle–foot orthoses. J Rehabil Res Dev 46:257–268, 2009.CrossRefPubMedGoogle Scholar
  28. 28.
    Yates, G. A method for the provision of lightweight aesthetic orthopaedic appliances. Orthopedics. Oxford 1:153–162, 1968.Google Scholar
  29. 29.
    Zissimopoulos, A., S. Fatone, and S. A. Gard. Biomechanical and energetic effects of a stance-control orthotic knee joint. J Rehabil Res Dev. 44:503–514, 2007.CrossRefPubMedGoogle Scholar

Copyright information

© Biomedical Engineering Society 2015

Authors and Affiliations

  • Feng Tian
    • 1
    • 2
  • Mohamed Samir Hefzy
    • 1
    Email author
  • Mohammad Elahinia
    • 2
  1. 1.Biomechanics and Assistive Technology Laboratory, Departments of Bioengineering and Mechanical, Industrial and Manufacturing Engineering, The College of EngineeringThe University of ToledoToledoUSA
  2. 2.Dynamic and Smart Systems Laboratory, Departments of Bioengineering and Mechanical, Industrial and Manufacturing Engineering, The College of EngineeringThe University of ToledoToledoUSA

Personalised recommendations