A method to calculate the centre of the ankle joint: A comparison with the Vicon Plug-in-Gait model

Syam Prabhakaran Nair, Sheila Gibbs, Graham Arnold, Rami Abboud, Weijie Wang

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)


    Background: In gait analysis, calculation of the ankle joint centre is a difficult task. The conventional way to calculate the ankle joint centre is using the Vicon Plug-in-Gait model. The present study proposes a new model, which calculates the joint centre from two markers positioned over the medial and lateral malleoli (i.e. Two-marker-model).

    Methods: In order to compare the proposed model with Plug-in-Gait model, gait data from healthy and patient subjects were captured using a motion capture system. The ankle joint centres were calculated by the two models. A test-retest experiment was carried out to check reliability and repeatability for Two-marker-model.

    Findings: Two ankle joint centres produced by two models were significantly different. The distances between two ankle joint centres were approximately 16.8 (mm), and the differences in the posterior-anterior, medial-lateral and inferior-superior directions were approximately 6.3, 7.7 and 8.2 (mm). Further error analysis highlighted that the probability of producing errors in Two-marker-model is lower than that in Plug-in-Gait model due to the Two-marker-model's simple and reliable marker positioning. The reliability and repeatability coefficients for the new model were greater than 0.9.

    Interpretation: In principle, the Plug-in-Gait model is more likely to produce errors than the Two-marker-model, because the former employs multiple markers from the pelvis to calf to define the ankle joint centre with marker positions being very user-dependent. The results suggest that the Two-marker-model can be considered an alternative to Plug-in-Gait model for calculating ankle joint centre. (C) 2010 Elsevier Ltd. All rights reserved.

    Original languageEnglish
    Pages (from-to)582-587
    Number of pages6
    JournalClinical Biomechanics
    Issue number6
    Publication statusPublished - Jul 2010


    • Joint centre
    • Model
    • Marker
    • Accuracy
    • Gait


    Dive into the research topics of 'A method to calculate the centre of the ankle joint: A comparison with the Vicon Plug-in-Gait model'. Together they form a unique fingerprint.

    Cite this