Biomechanical Effects of Variable Stiffness Shoes in Normal Walking After 60-minute Adaptation

  • Jaeyeon Wee
  • Jee Chin Teoh
  • Taeyong LeeEmail author
Regular Paper


The use of variable stiffness shoes (VSS) has been found to be conducive to reducing external knee adduction moment (EKAM). However, it is still unknown whether the claimed biomechanical effects of VSS remain after the subjects have adapted to the footwear. The objective of the study is to examine the effects of VSS immediately upon usage, as well as its effects after 60 min of adaptation. It is hypothesized that the lowering of EKAM is not just the short term biomechanical response due to the immediate use of VSS. Twenty subjects were instructed to walk in three shod conditions which are walking in control shoes, walking in VSS, and walking in VSS after 60-min of adaptation. All of the dynamic exercises were recorded simultaneously by VICON Motion Systems (Oxford Metric, UK). The results showed that EKAM was significantly reduced with the immediate use of VSS (8.43%, p < 0.05), as compared to the control shoes. The reduction remained significant, even after the given 60-min adaptation time. The effect of VSS on the reduction of EKAM is found to be consistent, even after familiarization. The use of VSS is postulated to be helpful in alleviating the loading across the medial compartment of the knee joint.


Knee osteoarthritis (OA) Variable stiffness shoe (VSS) External knee adduction moment (EKAM) 



This study was supported by National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIT) (NRF-2019R1F1A1058182).

Compliance with ethical standards

Conflict of interest

The authors declared that they have no conflict of interest.


  1. 1.
    Baliunas, A. J., Hurwitz, D. E., Ryals, A. B., Karrar, A., Case, J. P., Block, J. A., et al. (2002). Increased knee joint loads during walking are present in subjects with knee osteoarthritis. Osteoarthritis and Cartilage, 10(7), 573–579. Scholar
  2. 2.
    Blair, S. J., Lake, M. J., Sterzing, T. & Cheung, J. T. (2013) Lower extremity biomechanics following a period of adaptation to wearing unstable shoes. Footwear Science, 5(sup1), S139–S141. Scholar
  3. 3.
    Boyer, K. A., Federolf, P., Lin, C., Nigg, B. M., & Andriacchi, T. P. (2012). Kinematic adaptations to a variable stiffness shoe: Mechanisms for reducing joint loading. Journal of Biomechanics, 45(9), 1619–1624. Scholar
  4. 4.
    Chan, M.-S., Huang, S.-L., Shih, Y., Chen, C.-H., & Shiang, T.-Y. (2013). Shear cushions reduce the impact loading rate during walking and running. Sports Biomechanics, 12(4), 334–342. Scholar
  5. 5.
    Chen, W. M., Lee, T., Lee, P. V. S., Lee, J. W., & Lee, S. J. (2010). Effects of internal stress concentrations in plantar soft-tissue —A preliminary threedimensional finite element analysis. Medical Engineering & Physics, 32(4), 324–331. Scholar
  6. 6.
    Chen, W. M., Park, J., Park, S. B., Shim, V. P. M., & Lee, T. (2012). Role of gastrocnemius-soleus muscle in forefoot force transmission at heel rise —A 3D finite element analysis. Journal of Biomechanics, 45(10), 1783–1789. Scholar
  7. 7.
    Cheung, R. T. H., Wong, R. Y. L., Chung, T. K. W., Choi, R. T., Leung, W. W. Y., & Shek, D. H. Y. (2017). Relationship between foot strike pattern, running speed, and footwear condition in recreational distance runners. Sports Biomechanics, 16(2), 238–247. Scholar
  8. 8.
    Delattre, N., Chambon, N., Berton, E., Gueguen, N., & Rao, G. (2013). Effect of time during a running session with minimal footwear. Computer Methods in Biomechanics and Biomedical Engineering, 16(SUPPL 1), 104–105. Scholar
  9. 9.
    Drawer, S., & Fuller, C. W. (2001). Propensity for osteoarthritis and lower limb joint pain in retired professional soccer players. British Journal of Sports Medicine, 35(6), 402–408. Scholar
  10. 10.
    Erhart-Hledik, J. C., Elspas, B., Giori, N. J., & Andriacchi, T. P. (2012). Effect of variable-stiffness walking shoes on knee adduction moment, pain, and function in subjects with medial compartment knee osteoarthritis after 1 year. Journal of Orthopaedic Research, 30(4), 514–521. Scholar
  11. 11.
    Erhart, J. C., Dyrby, C. O., D’Lima, D. D., Colwell, C. W., & Andriacchi, T. P. (2010). Changes in in vivo knee loading with a variable-stiffness intervention shoe correlate with changes in the knee adduction moment. Journal of Orthopaedic Research, 28(12), 1548–1553. Scholar
  12. 12.
    Erhart, J. C., Mündermann, A., Elspas, B., Giori, N. J., & Andriacchi, T. P. (2008). A variable-stiffness shoe lowers the knee adduction moment in subjects with symptoms of medial compartment knee osteoarthritis. Journal of Biomechanics, 41(12), 2720–2725. Scholar
  13. 13.
    Erhart, J. C., Mündermann, A., Elspas, B., Giori, N. J., & Andriacchi, T. P. (2010). Changes in knee adduction moment, pain, and functionality with a variable-stiffness walking shoe after 6 months. Journal of Orthopaedic Research, 28(7), 873–879. Scholar
  14. 14.
    Fisher, D. S., Dyrby, C. O., Mündermann, A., Morag, E., & Andriacchi, T. P. (2007). In healthy subjects without knee osteoarthritis, the peak knee adduction moment influences the acute effect of shoe interventions designed to reduce medial compartment knee load. Journal of Orthopaedic Research, 25(4), 540–546. Scholar
  15. 15.
    Foroughi, N., Smith, R., & Vanwanseele, B. (2009). The association of external knee adduction moment with biomechanical variables in osteoarthritis: a systematic review. The Knee, 16, 303–309. Scholar
  16. 16.
    Hardin, E. C., Van Den Bogert, A. J., & Hamill, J. (2004). Kinematic adaptations during running: effects of footwear, surface, and duration. Medicine and Science in Sports and Exercise, 36(5), 838–844.CrossRefGoogle Scholar
  17. 17.
    Jenkyn, T. R., Erhart, J. C., & Andriacchi, T. P. (2011). An analysis of the mechanisms for reducing the knee adduction moment during walking using a variable stiffness shoe in subjects with knee osteoarthritis. Journal of Biomechanics, 44(7), 1271–1276. Scholar
  18. 18.
    Jung, Y., Koo, Y., & Koo, S. (2017). Simultaneous estimation of ground reaction force and knee contact force during walking and squatting. International Journal of Precision Engineering and Manufacturing, 18(9), 1263–1268.CrossRefGoogle Scholar
  19. 19.
    Kerrigan, D. C., Lelas, J. L., Goggins, J., Merriman, G. J., Kaplan, R. J., & Felson, D. T. (2002). Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis. Archives of Physical Medicine and Rehabilitation, 83(7), 889–893. Scholar
  20. 20.
    Kirtely, C., Whittle, M. W., & Jefferson, R. J. (1985). Influence of walking speed on gait parameters. Journal of Biomedical Engineering, 7(4), 282–288. Scholar
  21. 21.
    Lee, S., & Chae, S. W. (2019). Changes in contact pressure at the lower extremity joint with an unstable shoe. International Journal of Precision Engineering and Manufacturing, 20(9), 1611–1619.CrossRefGoogle Scholar
  22. 22.
    Litwic, A., Edwards, M., Dennison, E., & Cooper, C. (2013). Epidemiology and burden of osteoarthritis. British Medical Bulletin, 105, 185–199. Scholar
  23. 23.
    Mündermann, A., Dyrby, C. O., Hurwitz, D. E., Sharma, L., & Andriacchi, T. P. (2004). Potential strategies to reduce medial compartment loading in patients with knee osteoarthritis of varying severity: Reduced walking speed. Arthritis and Rheumatism, 50(4), 1172–1178. Scholar
  24. 24.
    Michaëlsson, K., Byberg, L., Ahlbom, A., Melhus, H., & Farahmand, B. Y. (2011). Risk of severe knee and hip osteoarthritis in relation to level of physical exercise: A prospective cohort study of long-distance Skiers in Sweden. PLoS ONE. Scholar
  25. 25.
    Miyazaki, T., Wada, M., Kawahara, H., Sato, M., Baba, H., & Shimada, S. (2002). Dynamic load at baseline can predict radiographic disease progression in medial compartment knee osteoarthritis. Annals of the Rheumatic Diseases, 61(7), 617–622. Scholar
  26. 26.
    Nashner, L. M., Woollacott, M., & Tuma, G. (1979). Organization of rapid responses to postural and locomotor-like perturbations of standing man. Experimental Brain Research, 36(3), 463–476. Scholar
  27. 27.
    Oliveria, S. A., Felson, D. T., Reed, J. I., Cirillo, P. A., & Walker, A. M. (1995). Incidence of symptomatic hand, hip, and knee osteoarthritis among patients in a health maintenance organization. Arthritis and Rheumatism, 38(8), 1134–1141. Scholar
  28. 28.
    Russell, E. M., & Hamill, J. (2011). Lateral wedges decrease biomechanical risk factors for knee osteoarthritis in obese women. Journal of Biomechanics, 44(12), 2286–2291. Scholar
  29. 29.
    Shelburne, K. B., Torry, M. R., Steadman, J. R., & Pandy, M. G. (2008). Effects of foot orthoses and valgus bracing on the knee adduction moment and medial joint load during gait. Clinical Biomechanics, 23(6), 814–821. Scholar
  30. 30.
    Shimada, S., Kobayashi, S., Wada, M., Uchida, K., Sasaki, S., Kawahara, H., et al. (2006). Effects of disease severity on response to lateral wedged shoe insole for medial compartment knee osteoarthritis. Archives of Physical Medicine and Rehabilitation, 87(11), 1436–1441. Scholar
  31. 31.
    Teoh, J. C., Low, J. H., Lim, Y. B., Shim, V. P. W., Park, J., Park, S. B., et al. (2013). Investigation of the biomechanical effect of variable stiffness shoe on external knee adduction moment in various dynamic exercises. Journal of Foot and Ankle Research. Scholar
  32. 32.
    Tetsworth, K., & Paley, D. (1994). Malalignment and degenerative arthropathy. Orthopedic Clinics of North America, 25(3), 367–377.Google Scholar
  33. 33.
    Yang, J. F., & Stein, R. B. (1990). Phase-dependent reflex reversal in human leg muscles during walking. Journal of Neurophysiology, 63(5), 1109–1117.CrossRefGoogle Scholar
  34. 34.
    Zhao, D., Banks, S. A., Mitchell, K. H., D’Lima, D. D., Colwell, C. W., Jr., & Fregly, B. J. (2007). Correlation between the knee adduction torque and medical contact force for a variety of gait patterns. Journal of Orthopaedic Research, 25(6), 789–797. Scholar

Copyright information

© Korean Society for Precision Engineering 2019

Authors and Affiliations

  1. 1.Division of Mechanical and Biomedical Engineering, ELTEC College of EngineeringEwha Womans UniversitySeoulRepublic of Korea

Personalised recommendations