Abstract
Recent studies which estimated foot segment kinetic patterns were found to have inconclusive data on one hand, and did not dissociate the kinetics of the chopart and lisfranc joint. The current study aimed therefore at reproducing independent, recently published three-segment foot kinetic data (Study 1) and in a second stage expand the estimation towards a four-segment model (Study 2).
Concerning the reproducibility study, two recently published three segment foot models (Bruening et al., 2014; Saraswat et al., 2014) were reproduced and kinetic parameters were incorporated in order to calculate joint moments and powers of paediatric cohorts during gait. Ground reaction forces were measured with an integrated force/pressure plate measurement set-up and a recently published proportionality scheme was applied to determine subarea total ground reaction forces. Regarding Study 2, moments and powers were estimated with respect to the Instituto Ortopedico Rizzoli four-segment model. The proportionality scheme was expanded in this study and the impact of joint centre location on kinetic data was evaluated.
Findings related to Study 1 showed in general good agreement with the kinetic data published by Bruening et al. (2014). Contrarily, the peak ankle, midfoot and hallux powers published by Saraswat et al. (2014) are disputed. Findings of Study 2 revealed that the chopart joint encompasses both power absorption and generation, whereas the Lisfranc joint mainly contributes to power generation.
The results highlights the necessity for further studies in the field of foot kinetic models and provides a first estimation of the kinetic behaviour of the Lisfranc joint.
Introduction
Where multi-segment kinematic foot models have received increasing attention in methodological and clinical studies (Deschamps et al., 2011, McGinley et al., 2009), kinetic models are deemed to be more challenging (Bruening et al., 2010). Additional needs for an inverse dynamic approach to estimate joint kinetics include joint centre(s) definition, estimation of resultant ground reaction forces (GRF) applied to each segment of the foot and the definition of segment initial properties. Only few multi-segment kinetic foot models (MSKFM) have been described in literature with different methodological approaches (Bruening et al., 2012a, MacWilliams et al., 2003, Saraswat et al., 2014). MacWilliams et al. (2003) proposed an eight segments kinetic model in which subarea forces were measured by a force platform and pressure platform throughout separate trials that were subsequently combined using an estimation method, neglecting medio-lateral forces between segments. Saraswat et al. (2014) described, in a paediatric population, a three segment kinetic foot model incorporating the hindfoot (calcaneus), forefoot (meta-tarsal joints) and hallux. For all foot segments, centre of pressure and resultant GRF, derived from combining force and pressure platform data, were computed for each frame of the segmented pressure data by estimating subarea shear forces and normal moment as a proportion of the measured normal forces (so-called proportionality scheme) (Saraswat et al., 2014). For any given segment i:
with Fz (normal force), Fx (anterior/posterior shear forces), Fy (medial/ lateral shear forces) and Mz (normal moment).
The predicted shear forces were found to be less than 3% different for all normalized shear forces in the hindoot and forefoot segments (Saraswat et al., 2014). Bruening et al. (2012a) described, in a high functioning paediatric population, a three segment kinetic foot model with a slightly different segment definition, i.e. hindfoot (calcaneus), forefoot (navicular, cuboid, cuneiforms, metatarsals) and hallux. Subarea GRF’s under the three segments were measured by participants having to adopt a three-step targeting approach on two adjacent force plates during a walking trial. By creating two sub models and calculating subarea GRF’s under each segment of the foot model, a closer insight into the kinetic behaviour of the hallux, midfoot and hindfoot was obtained (Bruening et al., 2012a). This method has been criticized because of poor clinical utility in low functioning persons.
Kinetic data of the two previously mentioned studies showed similar patterns but substantially different peak values and timing (Bruening et al., 2012a, Saraswat et al., 2014). These deviating findings may originate from (1) differences in definitions of joint rotation centres, (2) differences in subarea resultant GRF calculations and (3) the heterogeneity of paediatric populations. Results showed a tendency of rigid foot models to overestimate ankle joint kinetics. Bruening et al. (2012) identified an overestimation of up to 53% (35% on average) in peak power of the ankle in a single-segment model opposed to the three-segment foot model. This seems not illogical, as earlier invasive in vivo kinematic studies described relatively high amplitudes of midfoot (Chopart joint) and forefoot (Lisfranc joint) motion during walking, making it plausible to produce substantial amounts of power in these foot segments (Lundgren et al., 2008).
Based on the aforementioned literature, it can be concluded that the scientific community has uncovered a new area with high potential towards the management of foot and lower limb related pathologies. However, before the clinical application can be pursued with confidence there is a need to provide further clarity with respect to the inconclusive findings observed in the literature. It is also worthwhile to further expand the current knowledge and estimate the kinetic contribution of the Chopart and Lisfranc joint as separate anatomical entities.
Therefore, the aim of the current study was twofold. First, the reproducibility of the three-segment foot kinetic data recently published by two independent research groups was investigated (Bruening et al., 2012a, Saraswat et al., 2014). Second, the computation of foot kinetics was expanded to a four-segment model to determine the dynamic roles of the Chopart and Lisfranc joints.
Metadata
University: KU Leuven
Spokesperson: Kevin Deschamps (kevin.deschamps@kuleuven.be)
Domain: Rigid bodies
Location: Foot & ankle
Publications
Deschamps K, Eerdekens M, Desmet D, Matricali GA, Wuite S, Staes F, 2017. Estimation of foot joint kinetics in three and four segment foot models using an existing proportionality scheme: Application in paediatric barefoot walking Journal of Biomechanics 61, 168-175