Effect of external loading on in vitro measured muscle induced calcanear and talar motion
© Jonkers et al; licensee BioMed Central Ltd. 2008
Published: 26 September 2008
Several foot deformities (e.g. pes planus, pes cavus) result from muscular force imbalance across the joints of the ankle and foot. The use of in vitro measurements is required to explore the causal relation between muscle forces, individual foot bone movement and resulting foot deformities. This study quantified the effect of muscle action of the pretibial muscle groups, Mm. peronei as well as the Gastro-soleus on the three dimensional rotation of calcaneus and talus using in vitro measurements with a gait simulator consisting of pneumatic actuators. Furthermore, we tested the effect of altered load bearing conditions of the foot on the observed relations.
Pneumatic actuators exerted forces with increasing magnitude onto the tendons of the pretibial muscles (M. tibialis anterior, M. extensor hallucis and M. extensor digitorum longus), the tendons of both M. peronei and the Achilles tendon of a cadaver foot, placed in an anatomical position (neutral, upright standing). The resulting motion of bone embedded LEDs was tracked using an opto-electronic system (Krypton, Metris) and the resulting three-dimensional rotation of calcaneus and talus was quantified. Changes in ground reaction forces were measured using a Kistler force platform. These tests were repeated for loading of the foot of 0 N, 150 N and 300 N.
The load bearing condition of the foot needs to be accounted for when defining the causal relation between three-dimensional rotations of calcaneus and talus and forces exerted on muscle tendons through pneumatic actuators.
This article is published under license to BioMed Central Ltd.