Non-invasive isometric force measurement of plantar flexors in rats.

INTRODUCTION

Isometric muscle force measurement is a sensitive marker for motor function recovery in rat nerve repair models. Current methods of eliciting maximal isometric force with nerve stimulation cannot provide longitudinal data.

METHODS

We developed a novel method for measuring isometric muscle force with a device designed to allow minimally invasive nerve stimulation and measurement of plantar flexion force. This indirectly elicited muscle force was compared with muscle force elicited by direct muscle stimulation in 3 surgical models.

RESULTS

The force measured after sciatic nerve transection and repair followed a parabolic trend. There was a postinjury decrease in force that continued until postoperative day 42, after which the force increased with time, indicating muscle reinnervation.

CONCLUSIONS

This approach can track longitudinal changes in force in the most common animal model for studies of clinically relevant problems in the peripheral nerve field.