Investigation of the biomechanical effect of variable stiffness shoe on external knee adduction moment in various dynamic exercises

Jee C. Teoh, Jin H. Low, Ying B. Lim, Victor Phyau Wui Shim, Jaeyoung Park, Seung Bum Park, Sang J. Park, Taeyong Lee

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10 Scopus citations


Background: The growing ageing population and high prevalence of knee osteoarthritis (OA) in athletes across nations have created a strong demand for improved non-invasive therapeutic alternatives for knee OA. The aim of this study is to investigate the effect of the variable stiffness shoe (VSS), a new non-invasive therapeutic approach, on external knee adduction moment (EKAM) in various dynamic exercises. EKAM is believed to have positive correlation with the progression and development of knee OA.Methods: Thirty young participants (16 male and 14 female; age 22.6 ± 1.9 years) from National University of Singapore were enrolled in this study. The tested activities were walking, running, drop-landing, and lateral hopping. All the dynamic exercises were recorded simultaneously by the 8-camera VICON Motion Systems (Oxford Metric, UK) with a sampling rate of 100 Hz.Results: The results showed that the EKAM was reduced in all the dynamic exercises with the use of VSS. The VSS produced significant reductions in the peak EKAM during walking (4.97%, p = 0.039), running (11.15%, p = 0.011), drop-landing (11.18%, p = 0.038) and lateral hopping (17.34%, p = 0.023) as compared to the control shoe.Conclusions: The reduction of EKAM with the use of VSS in various dynamic exercises demonstrates its potential in delaying the onset and the progression of knee OA in early stage of knee OA patients.

Original languageEnglish
Article number39
JournalJournal of Foot and Ankle Research
Issue number1
StatePublished - 17 Sep 2013

Bibliographical note

Funding Information:
This work was supported by a grant from the Temasek Defence Systems Institute (Project number: TDSI/09-009/1A), Singapore. The authors would also like to thank HwaSeung Corp. Ltd., Korea, for providing the intervention shoes used in this study.


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


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