Andersen, MS

Koning, B

Krautwurst, BK

Mellon, S

Stebbins, J

Zavatsky, A

Mellon, Stephen

Oxford University Research Archive

Muscle length in flatfeet and neutral feet using a new multi-segment, musculoskeletal foot model  B.K. Krautwurst1,2, S. Mellon2, B. Koning3,  A. Zavatsky4, M.S. Andersen 5, J. Stebbins6  1. Heidelberg University Hospital, Clinic for Orthopedics and Trauma Surgery, Heidelberg, Germany. 2. University of Oxford, Nuffield Department of Orthopaedics- Rheumatology & Musculoskeletal Sciences, Oxford, United Kingdom. 3. University Hospitals Coventry & Warwickshire NHS Trust, Gait Laboratory, Coventry, United Kingdom. 4. University of Oxford, Institute of Biomedical Engineering, Oxford, United Kingdom. 5. Aalborg University, Department of Materials and Production, Aalborg, Denmark. 6. Oxford University Hospitals NHS Foundation Trust, Oxford Gait Laboratory, Oxford, United Kingdom.  Introduction Flatfoot deformity is common in children as shown by studies using magnetic resonance images (MRI), X-ray or conventional 3D gait analysis. There are some musculoskeletal foot models, which illustrate the joint motions within the foot [1, 2]. The calculated muscle length can describe structural differences between neutral and flatfeet. However, there is no study that uses these models to assess biomechanical alterations during walking, such as differences in muscle lengths within the foot for subjects with and without flatfoot pathology. To achieve this aim, subject-specific, 5-segment foot models were created using kinematics from motion capture and MRI scans to calculate muscle lengths during walking.  Research Question What are the differences in muscle lengths during walking for children with and without flatfeet?  Methods Six children with neutral feet and seven with flatfeet underwent a 3D gait analysis including the Oxford Foot Model (OFM) [3]. A new five-segment (shank, hind-, mid-, forefoot and hallux) musculoskeletal foot model was created in AnyBody (AnyBody Technology, Aalborg, Denmark) to calculate muscle lengths. Anatomical points and marker locations were collected from MRI for every child to define joint axes, muscle points (origins, via points, insertions) and gait marker positions for each segment. The muscle lengths of the plantar aponeurosis, tibialis posterior, tibialis anterior and peroneus longus were normalized to the average shank and foot length of all children. Particular attention was given to the second half of the stance phase (terminal stance and preswing) since these have been shown to be the most important gait phases for flatfeet [3].  Results Children with flatfeet showed a longer plantar aponeurosis and tibialis posterior, especially in terminal stance and preswing (50-65% of gait cycle) compared to neutral feet (see figure). Furthermore, the tibialis anterior and peroneus longus were shorter in flatfeet and there is hardly any elongation of the peroneus longus in preswing.  Discussion Especially in the gait phases (end of stance and beginning of swing phase) in which the medial arch should elevate and the heel invert, the plantar aponeurosis and tibialis posterior were not able to shorten sufficiently and the peroneus longus did not elongate in children with flatfeet. This may be one reason why the medial arch is lower in flatfeet compared to neutral feet. This is a preliminary study – To generalise and validate these results, the model should be further validated and more subjects included.  References [1] Nester et al. 2007, J Biomech, 40, 3412-3423 [2] Oosterwaal et al. 2016, J Foot Ankle Res, 9-19 [3] Kothari et al. 2015, Gait Posture, 41, 786-790  Acknowledgements The scholarship to perform this project was sponsored by Deutsche Forschungsgesellschaft (German Research Association). There is no conflict relating the subject and a company.      Fig. 1. Normalized muscle length in flatfeet (blue dotted line) and normal feet (red continuous line) during the gait cycle. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) 

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Muscle length in flatfeet and neutral feet using a new multi-segment, musculoskeletal foot model

Muscle length in flatfeet and neutral feet using a new multi-segment, musculoskeletal foot model

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