A model for lever-arm length calculation of the flexor and extensor muscles at the ankle

Alberto Leardini, John J. O'Connor

Research output: Contribution to journalArticle

Abstract

A sagittal-plane mathematical model of joint mobility, including the mechanical effect of the extensor retinacula, was used to predict the lever arm lengths of the main flexor and extensor muscles of the human ankle over the range of movement. In plantarflexion, the centre of rotation lies posteriorly and distally, maximising the lever arm of the tibialis anterior. The action of the gastrocnemius and soleus is maximised in dorsiflexion. Traditional calculation of ankle joint moment based on a fixed centre of rotation is acceptable only in exercises such as level walking with a limited range of motion about the neutral position. The present model with a moving centre is particularly advised in exercises which take the joint nearer to the extremes of sagittal motion.

Original languageEnglish
Pages (from-to)220-229
Number of pages10
JournalGait and Posture
Volume15
Issue number3
DOIs
Publication statusPublished - 2002

Keywords

  • Ankle complex
  • Centre of rotation
  • Four-bar linkage
  • Lever arm
  • Muscle force

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

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