The Analgesic Efficacy of Periarticular Infiltration of Local Anaesthetic for Total Hip Replacement

Total hip replacement is a major surgical procedure usually associated with significant pain in the early postoperative period. In our hospital, total hip replacement is routinely performed under spinal anaesthesia with intrathecal bupivacaine local anaesthetic plus opioid in the form of preservative free morphine. The use of 'local infiltration analgesia' as an alternative postoperative analgesic technique has been investigated.In this technique the surgeon infiltrates the surgical site with a long-acting local anaesthetic and places a catheter under direct vision which remains in situ and is used to administer local anaesthetic in the postoperative period until such time as it is removed (when no longer deemed necessary for pain relief or at a pre-set time in the postoperative period e.g. 48 hours). We hypothesize that infiltration of the surgical site with peri- and intraarticular levobupivacaine local anaesthetic would be an efficacious pain management technique and would not be inferior to intrathecal morphine for postoperative pain management.

• Drug: Levobupivacaine
  peri- and intraarticular surgical site infiltration before wound closure with a solution of levobupivacaine 0.5% 2mg/kg body weight with epinephrine made up to a volume of 1.5ml/kg with saline. A catheter will be placed by the surgeon before closure under the sterile surgical conditions and this will be left in situ in the wound. An elastomeric pump will deliver a continuous infusion of levobupivacaine 0.25% at 4ml/hr commencing 6 hours postoperatively and continuing for 24 hours.
• Drug: Intrathecal morphine
  intrathecal morphine bolus 200 micrograms

• Experimental: Levobupivacaine infiltration
  Patients will receive spinal anaesthesia with intrathecal bupivacaine, and will receive peri- and intraarticular surgical site infiltration during surgery and before wound closure with a solution of levobupivacaine 0.5% 2mg/kg body weight with epinephrine made up to a volume of 1.5ml/kg with saline. A catheter will be placed by the surgeon before closure and this will be left in situ in the wound. The catheter will be sited under the fascia lata exiting antero-superior to the incision. A bacterial filter will be attached and it will be connected to an elastomeric pump which will deliver a continuous infusion of levobupivacaine 0.25% at 4ml/hr commencing 6 hours postoperatively and continuing for 24 hours.
  Intervention: Drug: Levobupivacaine
• Control
  Patients will receive spinal anaesthesia with intrathecal bupivacaine 0.5% (17.5 mg if greater than 70 kg and 15 mg if less than 70 kg) and preservative-free morphine (0.2 mg).
  Intervention: Drug: Intrathecal morphine

Inclusion Criteria:

• Patients scheduled for unilateral total hip replacement
• Consent to spinal anaesthesia
• ASA Grade I to III

Exclusion Criteria:

• Patient refusal
• Mini-Mental Score < 25
• Allergy to bupivacaine, morphine, paracetamol, diclofenac
• Skin lesions/infection at site of injection
• Uncorrected renal dysfunction
• Coagulation disorders
• chronic pain condition other than hip pain