Preoperative static clinical evaluation of the spastic triceps surae often fails to indicate which of the two muscles (soleus or gastrocnemius) is the more distorted in its phasic activity during walking or in response to stretch. Gait electromyography is a method of distinguishing gastrocnemius from soleus problems. We customarily perform electromyographic studies prior to surgery. If isolated gastrocnemius phase distortion or clonus, or both, is found, a gastrocnemius recession is performed. When combined soleus and gastrocnemius problems are noted an Achilles-tendon lengthening is done.