<qa>  What is the method used to place perineural catheter?Research study to determine if pain relief following foot andor ankle surgery is influenced by the technique used to place perineural catheter. The catheters are placed using ultrasound-guidance or nerve stimulation and the method is selected at random using a computer program. This may help to determine if one of these methods is associated with an increased success rate and incidence of foot numbness during the infusion. 