Clinical Orthopaedics and Related Research®

, Volume 472, Issue 10, pp 3093–3101 | Cite as

Does a Microprocessor-controlled Prosthetic Knee Affect Stair Ascent Strategies in Persons With Transfemoral Amputation?

  • Jennifer M. Aldridge Whitehead
  • Erik J. Wolf
  • Charles R. Scoville
  • Jason M. Wilken
Symposium: Recent Advances in Amputation Surgery and Rehabilitation



Stair ascent can be difficult for individuals with transfemoral amputation because of the loss of knee function. Most individuals with transfemoral amputation use either a step-to-step (nonreciprocal, advancing one stair at a time) or skip-step strategy (nonreciprocal, advancing two stairs at a time), rather than a step-over-step (reciprocal) strategy, because step-to-step and skip-step allow the leading intact limb to do the majority of work. A new microprocessor-controlled knee (Ottobock X2®) uses flexion/extension resistance to allow step-over-step stair ascent.


We compared self-selected stair ascent strategies between conventional and X2® prosthetic knees, examined between-limb differences, and differentiated stair ascent mechanics between X2® users and individuals without amputation. We also determined which factors are associated with differences in knee position during initial contact and swing within X2® users.


Fourteen individuals with transfemoral amputation participated in stair ascent sessions while using conventional and X2® knees. Ten individuals without amputation also completed a stair ascent session. Lower-extremity stair ascent joint angles, moment, and powers and ground reaction forces were calculated using inverse dynamics during self-selected strategy and cadence and controlled cadence using a step-over-step strategy.


One individual with amputation self-selected a step-over-step strategy while using a conventional knee, while 10 individuals self-selected a step-over-step strategy while using X2® knees. Individuals with amputation used greater prosthetic knee flexion during initial contact (32.5°, p = 0.003) and swing (68.2°, p = 0.001) with higher intersubject variability while using X2® knees compared to conventional knees (initial contact: 1.6°, swing: 6.2°). The increased prosthetic knee flexion while using X2® knees normalized knee kinematics to individuals without amputation during swing (88.4°, p = 0.179) but not during initial contact (65.7°, p = 0.002). Prosthetic knee flexion during initial contact and swing were positively correlated with prosthetic limb hip power during pull-up (r = 0.641, p = 0.046) and push-up/early swing (r = 0.993, p < 0.001), respectively.


Participants with transfemoral amputation were more likely to self-select a step-over-step strategy similar to individuals without amputation while using X2® knees than conventional prostheses. Additionally, the increased prosthetic knee flexion used with X2® knees placed large power demands on the hip during pull-up and push-up/early swing. A modified strategy that uses less knee flexion can be used to allow step-over-step ascent in individuals with less hip strength.

Level of Evidence

Level II, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.


Knee Flexion Knee Flexion Angle Prosthetic Limb Peak Knee Flexion Stair Ascent 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank Elizabeth Nottingham BS and Alison Linberg DPT for their help with data collection and processing.


  1. 1.
    Andriacchi TP, Andersson GB, Fermier RW, Stern D, Galante JO. A study of lower-limb mechanics during stair-climbing. J Bone Joint Surg Am. 1980;62:749–757.PubMedGoogle Scholar
  2. 2.
    Bae TS, Choi K, Hong D, Mun M. Dynamic analysis of above-knee amputee gait. Clin Biomech (Bristol, Avon). 2007;22:557–566.PubMedCrossRefGoogle Scholar
  3. 3.
    Bae TS, Choi K, Mun M. Level walking and stair climbing gait in above-knee amputees. J Med Eng Technol. 2009;33:130–135.PubMedCrossRefGoogle Scholar
  4. 4.
    Bellmann M, Schmalz T, Ludwigs E, Blumentritt S. Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation. Arch Phys Med Rehabil. 2012;93:541–549.PubMedCrossRefGoogle Scholar
  5. 5.
    Bellmann M, Schmalz T, Ludwigs E, Blumentritt S. Stair ascent with an innovative microprocessor-controlled exoprosthetic knee joint. Biomed Eng (NY). 2012;57:435–444.Google Scholar
  6. 6.
    Costigan PA, Deluzio KJ, Wyss UP. Knee and hip kinetics during normal stair climbing. Gait Posture. 2002;16:31–37.PubMedCrossRefGoogle Scholar
  7. 7.
    Hafner BJ, Willingham LL, Buell NC, Allyn KJ, Smith DG. Evaluation of function, performance, and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee. Arch Phys Med Rehabil. 2007;88:207–217.PubMedCrossRefGoogle Scholar
  8. 8.
    Hobara H, Kobayashi Y, Tominaga S, Nakamura T, Yamasaki N, Ogata T. Factors affecting stair-ascent patterns in unilateral transfemoral amputees. Prosthet Orthot Int. 2013;37:222–226.PubMedCrossRefGoogle Scholar
  9. 9.
    International Code Council. International residential code for one- and two-family dwellings. 2007. Available at: Accessed January 14, 2014.
  10. 10.
    McFadyen BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech. 1988;21:733–744.PubMedCrossRefGoogle Scholar
  11. 11.
    Nadeau S, McFadyen BJ, Malouin F. Frontal and sagittal plane analyses of the stair climbing task in healthy adults aged over 40 years: what are the challenges compared to level walking? Clin Biomech (Bristol, Avon). 2003;18:950–959.PubMedCrossRefGoogle Scholar
  12. 12.
    Narang I, Mathur B, Singh P, Jape V. Functional capabilities of lower limb amputees. Prosthet Orthot Int. 1984;8:43–51.PubMedGoogle Scholar
  13. 13.
    Ottobock. C-Leg: the standard of care. 2013. Available at: Accessed April 16, 2013.
  14. 14.
    Reid SM, Lynn SK, Musselman RP, Costigan PA. Knee biomechanics of alternate stair ambulation patterns. Med Sci Sports Exerc. 2007;39:2005–2011.PubMedCrossRefGoogle Scholar
  15. 15.
    Rowe PJ, Myles CM, Walker C, Nutton R. Knee joint kinematics in gait and other functional activities measured using flexible electrogoniometry: how much knee motion is sufficient for normal daily life? Gait Posture. 2000;12:143–155.PubMedCrossRefGoogle Scholar
  16. 16.
    Schmalz T, Blumentritt S, Marx B. Biomechanical analysis of stair ambulation in lower limb amputees. Gait Posture. 2007;25:267–278.PubMedCrossRefGoogle Scholar
  17. 17.
    Sinitski EH, Hansen AH, Wilken JM. Biomechanics of the ankle-foot system during stair ambulation: implications for design of advanced ankle-foot prostheses. J Biomech. 2012;45:588–594.PubMedCrossRefGoogle Scholar
  18. 18.
    Wilken JM, Rodriguez KM, Brawner M, Darter BJ. Reliability and minimal detectible change values for gait kinematics and kinetics in healthy adults. Gait Posture. 2012;35:301–307.PubMedCrossRefGoogle Scholar
  19. 19.
    Wilken JM, Sinitski EH, Bagg EA. The role of lower extremity joint powers in successful stair ambulation. Gait Posture. 2011;34:142–144.PubMedCrossRefGoogle Scholar
  20. 20.
    Zahedi S, Sykes A, Lang S, Cullington I. Adaptive prosthesis—a new concept in prosthetic knee control. Robotica. 2005;23:337–344.CrossRefGoogle Scholar

Copyright information

© The Association of Bone and Joint Surgeons® 2014

Authors and Affiliations

  • Jennifer M. Aldridge Whitehead
    • 1
  • Erik J. Wolf
    • 2
  • Charles R. Scoville
    • 3
  • Jason M. Wilken
    • 1
  1. 1.DOD-VA Extremity Trauma and Amputation Center of Excellence, Center for the Intrepid, Department of Orthopaedics and RehabilitationBrooke Army Medical CenterFt Sam HoustonUSA
  2. 2.DOD-VA Extremity Trauma and Amputation Center of Excellence, Department of RehabilitationWalter Reed National Military Medical CenterBethesdaUSA
  3. 3.Department of RehabilitationWalter Reed National Military Medical CenterBethesdaUSA

Personalised recommendations