The Amsterdam Foot Model: a clinically informed multi‐segment foot model developed to minimize measurement errors in foot kinematics

Abstract

Background Foot and ankle joint kinematics are measured during clinical gait analyses with marker-based multi-segment foot models. To improve on existing models, measurement errors due to soft tissue artifacts (STAs) and marker misplacements should be reduced. Therefore, the aim of this study is to define a clinically informed, universally applicable multi-segment foot model, which is developed to minimize these measurement errors. Methods The Amsterdam foot model (AFM) is a follow-up of existing multi-segment foot models. It was developed by consulting a clinical expert panel and optimizing marker locations and segment definitions to minimize measurement errors. Evaluation of the model was performed in three steps. First, kinematic errors due to STAs were evaluated and compared to two frequently used foot models, i.e. the Oxford and Rizzoli foot models (OFM, RFM). Previously collected computed tomography data was used of 15 asymptomatic feet with markers attached, to determine the joint angles with and without STAs taken into account. Second, the sensitivity to marker misplacements was determined for AFM and compared to OFM and RFM using static standing trials of 19 asymptomatic subjects in which each marker was virtually replaced in multiple directions. Third, a preliminary inter- and intra-tester repeatability analysis was performed by acquiring 3D gait analysis data of 15 healthy subjects, who were equipped by two testers for two sessions. Repeatability of all kinematic parameters was assessed through analysis of the standard deviation (σ) and standard error of measurement (SEM). Results The AFM was defined and all calculation methods were provided. Errors in joint angles due to STAs were in general similar or smaller in AFM (≤2.9°) compared to OFM (≤4.0°) and RFM (≤6.7°). AFM was also more robust to marker misplacement than OFM and RFM, as a large sensitivity of kinematic parameters to marker misplacement (i.e. > 1.0°/mm) was found only two times for AFM as opposed to six times for OFM and five times for RFM. The average intra-tester repeatability of AFM angles was σ:2.2[0.9°], SEM:3.3 ± 0.9° and the inter-tester repeatability was σ:3.1[2.1°], SEM:5.2 ± 2.3°. Conclusions Measurement errors of AFM are smaller compared to two widely-used multi-segment foot models. This qualifies AFM as a follow-up to existing foot models, which should be evaluated further in a range of clinical application areas.

Using surface markers to describe the kinematics of the medial longitudinal arch

“…Since this study evaluated a novel method for characterising the MLA, with no previous data available, a formal a priori sample size calculation could not be performed. However, the sample size used in this study (60 feet from 30 participants) is in agreement with comparable studies in the literature [9,[19][20][21].…”

“…This is due to the natural anatomical position of the navicular marker and the particular role it holds in MLA function [25]. It is also known to have a low rate of measurement error including marker misplacement and soft tissue artifacts [21]. Additionally, the use of the navicular marker for representing the MLA has been confirmed in studies using plain x-rays [14] and biplanar fluoroscopy [29,30].…”

Three-dimensional gait analysis of orthopaedic common foot and ankle joint diseases

“…With the advancement of gait analysis technology, multisegment foot models (MFMs) can explain the above problems by analysing the relative motion between the internal segments of the foot. A variety of MFMs have been developed ( Kadaba et al, 1990 ; Kidder et al, 1996 ; MacWilliams et al, 2003 ; Simon et al, 2006 ; Leardini et al, 2007 ; Henley et al, 2008 ; Wright et al, 2011 ; Oosterwaal et al, 2011 ; De Mits et al, 2012 ; Saraswat et al, 2012 ; Schallig et al, 2022 ) ( Table 1 ), and there has been much discussion on the application of these models.…”

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“…motion of individual bones, or muscle forces). These multi-segment foot models consider 3-26 foot segments, with up to 35 degrees of freedom [33][34][35][36][37]. Existing models include up to 30 intrinsic foot muscles and up to 66 ankle-foot ligaments [34,35].…”