The role of glutamate in the development of phantom limb pain

INTERVENTION: All patients will have spinal and epidural anaesthesia with bupivacaine established before amputation and will receive an epidural infusion of bupivacaine for 48 to 72 hours after surgery for post‐operative analgesia. Patients will be randomised to receive either: 1. An epidural bolus of ketamine before surgery followed by epidural ketamine infusion for 48 to 72 hours 2. A placebo CONDITION: Pain ; Signs and Symptoms ; Pain PRIMARY OUTCOME: Incidence and severity of post‐amputation pain measured at one year. SECONDARY OUTCOME: Not provided at time of registration INCLUSION CRITERIA: 1. Patients undergoing lower limb amputation for peripheral vascular disease or as a result of complications of diabetes mellitus 2. Able to give informed consent and cooperate with pain assessment