Previously, intravenous, intrathecal or oral opioids were the mainstay of postoperative analgesia following TKA. Although variably effective, the resulting analgesia is associated with well recognized adverse effects including nausea, vomiting, pruritus and sedation. Each adverse effect is unpleasant and likely to impede recovery and participation in PT. Epidural catheters and femoral nerve blocks have both been used for postoperative analgesia in this setting, but each is associated with lower limb motor weakness which hinders early implementation of PT and may increase the risk of falls.