Tension transduction device for functional evaluation of the rat peroneal nerve

Current techniques for evaluating animal model nerve regeneration lack accurate, sensitive and reproducible methods to determine neuromuscular function. We have developed a tension transduction apparatus which measures the magnitude of ankle dorsiflexion produced by normal rats during bipolar stimulation of the surgically exposed peroneal nerve. Three groups of animals were used to evaluate the consistency and overall reliability of this apparatus. Within the first group of 4 animals, we determined variability in a single testing period of 8 successive stimulations. The mean normalized standard deviation of dorsiflexion tension produced was 2.9% of the mean. In the second group, comparison of right and left dorsiflexion tension in 8 animals showed a difference of less than 2% (right: 134.2 g; left: 131.6 g), demonstrating that one lower limb can be used as a control for the contralateral limb. In the third group, 12 animals were tested on two separate occasions, 2 months apart, tension production increased 10% (from 122 to 134 g) and corresponded with an average weight increase, per animal, of 100 g (30%) during the 2-month rest period. Despite the increase in weight and strength, the initial procedure had a negative effect upon the maximum tension produced compared to a previously unoperated leg (prior operation: 134 g; no prior operation: 144 g). The reproducibility of data obtainable with this new device allows for its incorporation in future studies, as well as the correlation of such functional data with other current methods of studying nerve regeneration.