Personalisation of Plantarflexor Musculotendon Model Parameters in Children with Cerebral Palsy

Kirsten Veerkamp, Marjolein M. van der Krogt, Jaap Harlaar, Thomas D. O’Brien, Barbara Kalkman, Ajay Seth, Lynn Bar-On

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)


Neuromusculoskeletal models can be used to evaluate aberrant muscle function in cerebral palsy (CP), for example by estimating muscle and joint contact forces during gait. However, to be accurate, models should include representative musculotendon parameters. We aimed to estimate personalised parameters that capture the mechanical behaviour of the plantarflexors in children with CP and typically developing (TD) children. Ankle angle (using motion capture), torque (using a load-cell), and medial gastrocnemius fascicle lengths (using ultrasound) were measured during slow passive ankle dorsiflexion rotation for thirteen children with spastic CP and thirteen TD children. Per subject, the measured rotation was input to a scaled OpenSim model to simulate the torque and fascicle length output. Musculotendon model parameters were personalised by the best match between simulated and experimental torque–angle and fascicle length-angle curves according to a least-squares fit. Personalised tendon slack lengths were significantly longer and optimal fibre lengths significantly shorter in CP than model defaults and than in TD. Personalised tendon compliance was substantially higher in both groups compared to the model default. The presented method to personalise musculotendon parameters will likely yield more accurate simulations of subject-specific muscle mechanics, to help us understand the effects of altered musculotendon properties in CP.
Original languageEnglish
Pages (from-to)938-950
JournalAnnals of biomedical engineering
Issue number5
Early online date2022
Publication statusPublished - 1 May 2023


  • Achilles tendon
  • Biomechanical simulation
  • Calf muscles
  • Contracture
  • Muscle mechanics
  • Neuromusculoskeletal modelling
  • OpenSim
  • Subject specific
  • Triceps surae
  • Ultrasound

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